Asynchronous Processing of a Constellation of Geostationary and Polar-Orbiting Satellites for Fire Detection and Smoke Estimation

NASA Astrophysics Data System (ADS)

Hyer, E. J.; Peterson, D. A.; Curtis, C. A.; Schmidt, C. C.; Hoffman, J.; Prins, E. M.

2014-12-01

The Fire Locating and Monitoring of Burning Emissions (FLAMBE) system converts satellite observations of thermally anomalous pixels into spatially and temporally continuous estimates of smoke release from open biomass burning. This system currently processes data from a constellation of 5 geostationary and 2 polar-orbiting sensors. Additional sensors, including NPP VIIRS and the imager on the Korea COMS-1 geostationary satellite, will soon be added. This constellation experiences schedule changes and outages of various durations, making the set of available scenes for fire detection highly variable on an hourly and daily basis. Adding to the complexity, the latency of the satellite data is variable between and within sensors. FLAMBE shares with many fire detection systems the goal of detecting as many fires as possible as early as possible, but the FLAMBE system must also produce a consistent estimate of smoke production with minimal artifacts from the changing constellation. To achieve this, NRL has developed a system of asynchronous processing and cross-calibration that permits satellite data to be used as it arrives, while preserving the consistency of the smoke emission estimates. This talk describes the asynchronous data ingest methodology, including latency statistics for the constellation. We also provide an overview and show results from the system we have developed to normalize multi-sensor fire detection for consistency.

Global Earth Outgoing Radiation From A Constellation Of Satellites: Proof-Of-Concept Study

NASA Astrophysics Data System (ADS)

Gristey, J. J.; Chiu, J. Y. C.; Gurney, R. J.; Han, S. C.; Morcrette, C. J.

2017-12-01

The flux of radiation exiting at the top of the atmosphere, referred to as Earth Outgoing Radiation (EOR), constitutes a vital component of the Earth's energy budget. Since EOR is inherently connected to the rapidly evolving scene from which the radiation originates and exhibits large regional variations, it is of paramount importance that we can monitor EOR at a sufficient frequency and spatial scale for weather and climate studies. Achieving these criteria remains challenging using traditional measurement techniques. However, explosive development in small satellite technology and sensor miniaturisation has paved a viable route for measurements to be made from a constellation of satellites in different orbits. This offers an exciting new opportunity to make observations of EOR with both global coverage and high temporal resolution for the first time. To assess the potential of the constellation approach for observing EOR we perform a series of observing system simulation experiments. We will outline a baseline constellation configuration capable of sampling the Earth with unprecedented temporal resolution. Using this configuration and a sophisticated deconvolution technique, we demonstrate how to recover synoptic-scale global EOR to the accuracy required to understand Earth's global energy budget. Finally, we will reveal the impact of various modifications to the constellation configuration and provide recommendations for the community.

The COSMO-SkyMed ground and ILS and OPS segments upgrades for full civilian capacity exploitation

NASA Astrophysics Data System (ADS)

Fasano, L.; De Luca, G. F.; Cardone, M.; Loizzo, R.; Sacco, P.; Daraio, M. G.

2015-10-01

COSMO-SkyMed (CSK), is an Earth Observation joint program between Agenzia Spaziale Italiana (Italian Space Agency, ASI) and Italian Ministry of Defense (It-MoD). It consists of a constellation of four X Band Synthetic Aperture Radar (SAR) whose first satellite of has been launched on June 2007. Today the full constellation is fully qualified and is in an operative phase. The COSMO-SkyMed System includes 3 Segments: the Space Segment, the Ground Segment and the Integrated Logistic Support and Operations Segment (ILS and OPS) As part of a more complex re-engineering process aimed to improve the expected constellation lifetime, to fully exploit several system capabilities, to manage the obsolescence, to reduce the maintenance costs and to exploit the entire constellation capability for Civilian users a series of activities have been performed. In the next months these activities are planned to be completed and start to be operational so that it will be possible the programming, planning, acquisition, raw processing and archiving of all the images that the constellation can acquire.

Applications of Precipitation Feature Databases from GPM core and constellation Satellites

NASA Astrophysics Data System (ADS)

Liu, C.

2017-12-01

Using the observations from Global Precipitation Mission (GPM) core and constellation satellites, global precipitation was quantitatively described from the perspective of precipitation systems and their properties. This presentation will introduce the development of precipitation feature databases, and several scientific questions that have been tackled using this database, including the topics of global snow precipitation, extreme intensive convection, hail storms, extreme precipitation, and microphysical properties derived with dual frequency radars at the top of convective cores. As more and more observations of constellation satellites become available, it is anticipated that the precipitation feature approach will help to address a large variety of scientific questions in the future. For anyone who is interested, all the current precipitation feature databases are freely open to public at: http://atmos.tamucc.edu/trmm/.

Quantification of Transient Changes of Thermospheric Neutral Density

DTIC Science & Technology

2014-11-24

Pedersen conductivity at high latitudes. Based on Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) satellites...the model. The seasonal variations of the ratio have been investigated for both hemispheres, and an interhemispheric asymmetry has been identified...Satellite Program (DMSP) F- 15, F-16, F-17 and F-18 satellites and the Iridium satellite constellation is presented, using an inverse procedure for high

How to Enter, Fly In, and Exit the A-Train Constellation

NASA Technical Reports Server (NTRS)

Vincent, Mark A.

2015-01-01

The collaborative science obtained from the satellites in the A-Train is an unparalleled success. The constellation framework that has evolved is well-formulated and documented by its international members. Communication between teams is enhanced by a web-based Constellation Coordination System. Safety and correlated observations are ensured by defining independent control boxes with buffers in between. Each mission stays within its control box by regular drag makeup maneuvers. Annual inclination adjustments are coordinated by all missions to maintain their absolute and relative Mean Local Time of Ascending Node (MLTAN). Since the satellites are in different orbit planes their separation involves a three-dimensional triad made up of the along track separations, reference groundtracks and MLTAN's. For further safety, a Constellation Envelope has been defined to determine safe entry and exit orbits.

China national space remote sensing infrastructure and its application

NASA Astrophysics Data System (ADS)

Li, Ming

2016-07-01

Space Infrastructure is a space system that provides communication, navigation and remote sensing service for broad users. China National Space Remote Sensing Infrastructure includes remote sensing satellites, ground system and related systems. According to the principle of multiple-function on one satellite, multiple satellites in one constellation and collaboration between constellations, series of land observation, ocean observation and atmosphere observation satellites have been suggested to have high, middle and low resolution and fly on different orbits and with different means of payloads to achieve a high ability for global synthetically observation. With such an infrastructure, we can carry out the research on climate change, geophysics global surveying and mapping, water resources management, safety and emergency management, and so on. I This paper gives a detailed introduction about the planning of this infrastructure and its application in different area, especially the international cooperation potential in the so called One Belt and One Road space information corridor.

CALIPSO: Global Aerosol and Cloud Observations from Lidar and Passive Instruments

NASA Technical Reports Server (NTRS)

Poole, L. R.; Winker, D. M.; Pelon, J. R.; McCormick, M. P.

2002-01-01

CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Spaceborne Observations) is an approved satellite mission being developed through collaboration between NASA and the French space agency CNES. The mission is scheduled for launch in 2004 and will operate for 3 years as part of a five-satellite formation called the Aqua constellation. This constellation will provide a unique data set on aerosol and cloud optical and physical properties and aerosol-cloud interactions that will substantially increase our understanding of the climate system and the potential for climate change.

Determination of Earth outgoing radiation using a constellation of satellites

NASA Astrophysics Data System (ADS)

Gristey, Jake; Chiu, Christine; Gurney, Robert; Han, Shin-Chan; Morcrette, Cyril

2017-04-01

The outgoing radiation fluxes at the top of the atmosphere, referred to as Earth outgoing radiation (EOR), constitute a vital component of the Earth's energy budget. This EOR exhibits strong diurnal signatures and is inherently connected to the rapidly evolving scene from which the radiation originates, so our ability to accurately monitor EOR with sufficient temporal resolution and spatial coverage is crucial for weather and climate studies. Despite vast improvements in satellite observations in recent decades, achieving these criteria remains challenging from current measurements. A technology revolution in small satellites and sensor miniaturisation has created a new and exciting opportunity for a novel, viable and sustainable observation strategy from a constellation of satellites, capable of providing both global coverage and high temporal resolution simultaneously. To explore the potential of a constellation approach for observing EOR we perform a series of theoretical simulation experiments. Using the results from these simulation experiments, we will demonstrate a baseline constellation configuration capable of accurately monitoring global EOR at unprecedented temporal resolution. We will also show whether it is possible to reveal synoptic scale, fast evolving phenomena by applying a deconvolution technique to the simulated measurements. The ability to observe and understand the relationship between these phenomena and changes in EOR is of fundamental importance in constraining future warming of our climate system.

Real-Time Detection of Tsunami Ionospheric Disturbances with a Stand-Alone GNSS Receiver: An Integration of GPS and Galileo Systems

NASA Astrophysics Data System (ADS)

Savastano, Giorgio; Komjathy, Attila; Verkhoglyadova, Olga; Wei, Yong; Mazzoni, Augusto; Crespi, Mattia

2017-04-01

Tsunamis can produce gravity waves that propagate up to the ionosphere generating disturbed electron densities in the E and F regions. These ionospheric disturbances are studied in detail using ionospheric total electron content (TEC) measurements collected by continuously operating ground-based receivers from the Global Navigation Satellite Systems (GNSS). Here, we present results using a new approach, named VARION (Variometric Approach for Real-Time Ionosphere Observation), and for the first time, we estimate slant TEC (sTEC) variations in a real-time scenario from GPS and Galileo constellations. Specifically, we study the 2016 New Zealand tsunami event using GNSS receivers with multi-constellation tracking capabilities located in the Pacific region. We compare sTEC estimates obtained using GPS and Galileo constellations. The efficiency of the real-time sTEC estimation using the VARION algorithm has been demonstrated for the 2012 Haida Gwaii tsunami event. TEC variations induced by the tsunami event are computed using 56 GPS receivers in Hawai'i. We observe TEC perturbations with amplitudes up to 0.25 TEC units and traveling ionospheric disturbances moving away from the epicenter at a speed of about 316 m/s. We present comparisons with the real-time tsunami model MOST (Method of Splitting Tsunami) provided by the NOAA Center for Tsunami Research. We observe variations in TEC that correlate well in time and space with the propagating tsunami waves. We conclude that the integration of different satellite constellations is a crucial step forward to increasing the reliability of real-time tsunami detection systems using ground-based GNSS receivers as an augmentation to existing tsunami early warning systems.

Determining inter-system bias of GNSS signals with narrowly spaced frequencies for GNSS positioning

NASA Astrophysics Data System (ADS)

Tian, Yumiao; Liu, Zhizhao; Ge, Maorong; Neitzel, Frank

2017-12-01

Relative positioning using multi-GNSS (global navigation satellite systems) can improve accuracy, reliability, and availability compared to the use of a single constellation system. Intra-system double-difference (DD) ambiguities (ISDDAs) refer to the DD ambiguities between satellites of a single constellation system and can be fixed to an integer to derive the precise fixed solution. Inter-system ambiguities, which denote the DD ambiguities between different constellation systems, can also be fixed to integers on overlapping frequencies, once the inter-system bias (ISB) is removed. Compared with fixing ISDDAs, fixing both integer intra- and inter-system DD ambiguities (IIDDAs) means an increase of positioning precision through an integration of multiple GNSS constellations. Previously, researchers have studied IIDDA fixing with systems of the same frequencies, but not with systems of different frequencies. Integer IIDDAs can be determined from single-difference (SD) ambiguities, even if the frequencies of multi-GNSS signals used in the positioning are different. In this study, we investigated IIDDA fixing for multi-GNSS signals of narrowly spaced frequencies. First, the inter-system DD models of multi-GNSS signals of different frequencies are introduced, and the strategy for compensating for ISB is presented. The ISB is decomposed into three parts: 1) a float approximate ISB number that can be considered equal to the ISB of code pseudorange observations and thus can be estimated through single point positioning (SPP); 2) a number that is a multiple of the GNSS signal wavelength; and 3) a fractional ISB part, with a magnitude smaller than a single wavelength. Then, the relationship between intra- and inter-system DD ambiguity RATIO values and ISB was investigated by integrating GPS L1 and GLONASS L1 signals. In our numerical analyses with short baselines, the ISB parameter and IIDDA were successfully fixed, even if the number of observed satellites in each system was small.

Methods and Apparatuses for Signaling with Geometric Constellations in a Raleigh Fading Channel

NASA Technical Reports Server (NTRS)

Jones, Christopher R. (Inventor); Barsoum, Maged F. (Inventor)

2015-01-01

Communication systems are described that use signal constellations, which have unequally spaced (i.e., `geometrically` shaped) points. In many embodiments, the communication systems use specific geometric constellations that are capacity optimized at a specific SNR (signal to noise ratio). In addition, ranges within which the constellation points of a capacity optimized constellation can be perturbed and are still likely to achieve a given percentage of the optimal capacity increase compared to a constellation that maximizes d (sub min) (i.e. minimum distance between constellations) are also described. Capacity measures that are used in the selection of the location of constellation points include, but are not limited to, parallel decode (PD) capacity and joint capacity.

Methodology and Method and Apparatus for Signaling with Capacity Optimized Constellations

NASA Technical Reports Server (NTRS)

Barsoum, Maged F. (Inventor); Jones, Christopher R. (Inventor)

2016-01-01

Design Methodology and Method and Apparatus for Signaling with Capacity Optimized Constellation Abstract Communication systems are described that use geometrically PSK shaped constellations that have increased capacity compared to conventional PSK constellations operating within a similar SNR band. The geometrically shaped PSK constellation is optimized based upon parallel decoding capacity. In many embodiments, a capacity optimized geometrically shaped constellation can be used to replace a conventional constellation as part of a firmware upgrade to transmitters and receivers within a communication system. In a number of embodiments, the geometrically shaped constellation is optimized for an Additive White Gaussian Noise channel or a fading channel. In numerous embodiments, the communication uses adaptive rate encoding and the location of points within the geometrically shaped constellation changes as the code rate changes.

The Global Positioning System constellation as a space weather monitor

NASA Astrophysics Data System (ADS)

Morley, S.; Henderson, M. G.; Woodroffe, J. R.; Brito, T. V.

2016-12-01

The Global Positioning System (GPS) satellites are distributed across six orbital planes and follow near-circular orbits, with a 12 hour period, at an altitude of approximately 20200 km. The six orbital planes are distributed around the Earth and are nominally inclined at 55 degrees. Energetic particle detectors have been flown on the GPS constellation for more than two decades; by February 2016 there were 23 GPS satellites equipped with energetic particle instrumentation. The Combined X-ray Dosimeter (CXD), which is flown on 21 GPS satellites, has recently been cross-calibrated against electron data from the Van Allen Probes mission, demonstrating its utility for scientific research and radiation environment specification. Recently electron and proton flux data from these instruments, for the month of January 2014, have been publicly released. We will describe the GPS constellation from the perspective of its use as a monitor for space weather, review some of the key scientific results enabled by these instruments and show some recent observations from the constellation, including the 2015 St. Patrick's Day storm. Using data from multiple satellite missions we describe the dynamics of this storm in detail.

Methods and Apparatuses for Signaling with Geometric Constellations

NASA Technical Reports Server (NTRS)

Barsoum, Maged F. (Inventor); Jones, Christopher R. (Inventor)

2018-01-01

Communication systems are described that use signal constellations, which have unequally spaced (i.e. `geometrically` shaped) points. In many embodiments, the communication systems use specific geometric constellations that are capacity optimized at a specific SNR. In addition, ranges within which the constellation points of a capacity optimized constellation can be perturbed and are still likely to achieve a given percentage of the optimal capacity increase compared to a constellation that maximizes d.sub.min, are also described. Capacity measures that are used in the selection of the location of constellation points include, but are not limited to, parallel decode (PD) capacity and joint capacity.

Methods and apparatuses for signaling with geometric constellations

NASA Technical Reports Server (NTRS)

Jones, Christopher R. (Inventor); Barsoum, Maged F. (Inventor)

2012-01-01

Communication systems are described that use signal constellations, which have unequally spaced (i.e. geometrically shaped) points. In many embodiments, the communication systems use specific geometric constellations that are capacity optimized at a specific SNR. In addition, ranges within which the constellation points of a capacity optimized constellation can be perturbed and are still likely to achieve a given percentage of the optimal capacity increase compared to a constellation that maximizes d.sub.min, are also described. Capacity measures that are used in the selection of the location of constellation points include, but are not limited to, parallel decode (PD) capacity and joint capacity.

System Constellations as a Tool Supporting Organisational Learning and Change Processes

ERIC Educational Resources Information Center

Birkenkrahe, Marcus

2008-01-01

Originally developed in the context of family therapy, system constellations are introduced using an organisational learning and system theoretical framework. Constellations are systemic group interventions using a spatial representation of the system elements. They correspond to deutero-learning processes and use higher-order systemic thinking.…

Assessing the Impact of Pre-gpm Microwave Precipitation Observations in the Goddard WRF Ensemble Data Assimilation System

NASA Technical Reports Server (NTRS)

Chambon, Philippe; Zhang, Sara Q.; Hou, Arthur Y.; Zupanski, Milija; Cheung, Samson

2013-01-01

The forthcoming Global Precipitation Measurement (GPM) Mission will provide next generation precipitation observations from a constellation of satellites. Since precipitation by nature has large variability and low predictability at cloud-resolving scales, the impact of precipitation data on the skills of mesoscale numerical weather prediction (NWP) is largely affected by the characterization of background and observation errors and the representation of nonlinear cloud/precipitation physics in an NWP data assimilation system. We present a data impact study on the assimilation of precipitation-affected microwave (MW) radiances from a pre-GPM satellite constellation using the Goddard WRF Ensemble Data Assimilation System (Goddard WRF-EDAS). A series of assimilation experiments are carried out in a Weather Research Forecast (WRF) model domain of 9 km resolution in western Europe. Sensitivities to observation error specifications, background error covariance estimated from ensemble forecasts with different ensemble sizes, and MW channel selections are examined through single-observation assimilation experiments. An empirical bias correction for precipitation-affected MW radiances is developed based on the statistics of radiance innovations in rainy areas. The data impact is assessed by full data assimilation cycling experiments for a storm event that occurred in France in September 2010. Results show that the assimilation of MW precipitation observations from a satellite constellation mimicking GPM has a positive impact on the accumulated rain forecasts verified with surface radar rain estimates. The case-study on a convective storm also reveals that the accuracy of ensemble-based background error covariance is limited by sampling errors and model errors such as precipitation displacement and unresolved convective scale instability.

The NASA EV-2 CYGNSS Small Satellite Constellation Mission

NASA Astrophysics Data System (ADS)

Ruf, C. S.; Gleason, S.; Jelenak, Z.; Katzberg, S. J.; Ridley, A. J.; Rose, R.; Scherrer, J.; Zavorotny, V.

2012-12-01

The NASA EV-2 Cyclone Global Navigation Satellite System (CYGNSS) is a spaceborne mission focused on tropical cyclone (TC) inner core process studies. CYGNSS attempts to resolve the principle deficiencies with current TC intensity forecasts, which lies in inadequate observations and modeling of the inner core. The inadequacy in observations results from two causes: 1) Much of the inner core ocean surface is obscured from conventional remote sensing instruments by intense precipitation in the eye wall and inner rain bands. 2) The rapidly evolving (genesis and intensification) stages of the TC life cycle are poorly sampled in time by conventional polar-orbiting, wide-swath surface wind imagers. CYGNSS is specifically designed to address these two limitations by combining the all-weather performance of GNSS bistatic ocean surface scatterometry with the sampling properties of a constellation of satellites. The use of a dense constellation of nanosatellite results in spatial and temporal sampling properties that are markedly different from conventional imagers. Simulation studies will be presented which examine the sampling as functions of various orbit parameters of the constellation. Historical records of actual TC storm tracks are overlaid onto a simulated time series of the surface wind sampling enabled by the constellation. For comparison purposes, a similar analysis is conducted using the sampling properties of several past and present conventional spaceborne ocean wind scatterometers. Differences in the ability of the sensors to resolve the evolution of the TC inner core are examined. The spacecraft and constellation mission are described. The signal-to-noise ratio of the measured scattered signal and the resulting uncertainty in retrieved surface wind speed are also examined.

Methods and Apparatuses for Signaling with Geometric Constellations in a Raleigh Fading Channel

NASA Technical Reports Server (NTRS)

Barsoum, Maged F. (Inventor); Jones, Christopher R. (Inventor)

2017-01-01

Communication systems are described that use signal constellations, which have unequally spaced (i.e. `geometrically` shaped) points. In many embodiments, the communication systems use specific geometric constellations that are capacity optimized at a specific SNR, over the Raleigh fading channel. In addition, ranges within which the constellation points of a capacity optimized constellation can be perturbed and are still likely to achieve a given percentage of the optimal capacity increase compared to a constellation that maximizes d.sub.min, are also described. Capacity measures that are used in the selection of the location of constellation points include, but are not limited to, parallel decode (PD) capacity and joint capacity.

Second BRITE-Constellation Science Conference: Small satellites—big science, Proceedings of the Polish Astronomical Society volume 5

NASA Astrophysics Data System (ADS)

Zwintz, Konstanze; Poretti, Ennio

2017-09-01

In 2016 the BRITE-Constellation mission had been operational for more than two years. At that time, several hundreds of bright stars of various types had been observed successfully in the two BRITE lters and astonishing new discoveries had been made. Therefore, the time was ripe to host the Second BRITE-Constellation Science Conference: Small satellites | big science" from August 22 to 26, 2016, in the beautiful Madonnensaal of the University of Innsbruck, Austria. With this conference, we brought together the scientic community interested in BRITE-Constellation, pro- vided an update on the status of the mission, presented and discussed latest scientic results, shared our experiences with the data, illustrated successful cooperations between professional and amateur ground-based observers and BRITE scientists, and explored new ideas for future BRITE-Constellation observations.

The Global Precipitation Measurement (GPM) Mission: Overview and Status

NASA Technical Reports Server (NTRS)

Hou, Arthur

2008-01-01

The Global Precipitation Measurement (GPM) Mission is an international satellite mission to unify and advance global precipitation measurements from a constellation of dedicated and operational microwave sensors. The GPM concept centers on the deployment of a Core Spacecraft in a non-Sun-synchronous orbit at 65 degrees inclination carrying a dual-frequency precipitation radar (DPR) and a multi-frequency passive microwave radiometer (GMI) with high-frequency capabilities to serve as a precipitation physics observatory and calibration standard for the constellation radiometers. The baseline GPM constellation is envisioned to comprise conical-scanning microwave imagers (e.g., GMI, SSMIS, AMSR, MIS, MADRAS, GPM-Brazil) augmented with cross-track microwave temperature/humidity sounders (e.g., MHS, ATMS) over land. In addition to the Core Satellite, the GPM Mission will contribute a second GMI to be flown in a low-inclination (approximately 40 deg.) non-Sun-synchronous orbit to improve near real-time monitoring of hurricanes. GPM is a science mission with integrated applications goals aimed at (1) advancing the knowledge of the global water/energy cycle variability and freshwater availability and (2) improving weather, climate, and hydrological prediction capabilities through more accurate and frequent measurements of global precipitation. The GPM Mission is currently a partnership between NASA and the Japan Aerospace Exploration Agency (JAXA), with opportunities for additional partners in satellite constellation and ground validation activities. Within the framework of the inter-governmental Group ob Earth Observations (GEO) and Global Earth Observation System of Systems (GEOSS), GPM has been identified as a cornerstone for the Precipitation Constellation (PC) being developed under the auspices of Committee of Earth Observation Satellites (CEOS). The GPM Core Observatory is scheduled for launch in 2013, followed by the launch of the GPM Low-Inclination Observatory in 2014. An overview of the GPM mission status, instrument capabilities, ground validation plans, and anticipated scientific and societal benefits will be presented.

Methodology and method and appartus for signaling with capacity optimized constellations

NASA Technical Reports Server (NTRS)

Barsoum, Maged F. (Inventor); Jones, Christopher R. (Inventor)

2012-01-01

Communication systems are described that use geometrically shaped constellations that have increased capacity compared to conventional constellations operating within a similar SNR band. In several embodiments, the geometrically shaped is optimized based upon a capacity measure such as parallel decoding capacity or joint capacity. In many embodiments, a capacity optimized geometrically shaped constellation can be used to replace a conventional constellation as part of a firmware upgrade to transmitters and receivers within a communication system. In a number of embodiments, the geometrically shaped constellation is optimized for an Additive White Gaussian Noise channel or a fading channel.

Methodology and Method and Apparatus for Signaling with Capacity Optimized Constellations

NASA Technical Reports Server (NTRS)

Barsoum, Maged F. (Inventor); Jones, Christopher R. (Inventor)

2017-01-01

Communication systems are described that use geometrically shaped constellations that have increased capacity compared to conventional constellations operating within a similar SNR band. In several embodiments, the geometrically shaped is optimized based upon a capacity measure such as parallel decoding capacity or joint capacity. In many embodiments, a capacity optimized geometrically shaped constellation can be used to replace a conventional constellation as part of a firmware upgrade to transmitters and receivers within a communication system. In a number of embodiments, the geometrically shaped constellation is optimized for an Additive White Gaussian Noise channel or a fading channel.

A study of catasterisms in the 'phaenomena' of Aratus

NASA Astrophysics Data System (ADS)

Rousseau, A.; Dimitrakoudis, S.

We provide a fresh analysis of the constellations in Aratos Phenomena by using the astronomical program Cybersky (by Stephen Schimpf) to check each reference of constellations within the poem for validity in 2800 BCE and 300 BCE (the later accounting for the broader period of time covering Eudoxus of Cnidus and Aratus of Soli). In each case, the latitude of observation was chose to be 36 North in agreement with the area of the sky that is not covered in the descriptions of Aratus (and contains the unseen constellations for a particular latitude). Each constellation was traced back to its Greek mythological origin through tha various writers of antiquity. Our results are collected in a table of the constellations mentioned by Aratus in his epic poem, with respect to the ancient authors who have mentioned each constellation shaping its myth, the locations on the earth each constellation is associated with and the most likely date of observation according to Aratus description and taking into account precession and the proper motion of stars.

A New Synthesis for the Origin of the Greek Constellations

NASA Astrophysics Data System (ADS)

Schaefer, B. E.

2005-08-01

The Greek constellations constitute one of the longest enduring intellectual properties of humanity. While various papers attribute the origin of the constellations to many diverse possibilities, main stream historians view the origin as largely being in Mesopotamia after around 1350 BC with transmission to the Greeks around 500 BC or so. The evidence for this synthesis is cuneiform and iconographic records that first mention constellations from roughly 1350-500 BC. My recent research on precessional dating has added much detail to this old synthesis. The earliest surviving written description of the Greek constellations is Aratus' Phaenomenon, which is a copy of Eudoxus' lost book of the same name. Hipparchus' Commentary also extensively quotes from Eudoxus. With 172 observations from Eudoxus, I derive a precessional date of 1130 ± 80 BC and a latitude of 36.0 ± 0.9 degrees north. Further, the positioning of the southern void amongst the Greek constellations yields a date of 690 BC (with an uncertainty of 2-4 centuries) and a latitude of 33 degrees (with an uncertainty of 1-3 degrees) for the six southernmost constellations. The earliest surviving description of the Mesopotamian constellations is the MUL.APIN tablet series, with the oldest dated example from the 8th century BC. My precessional calculation gives a date of 1100 BC and a latitude of 33 north. I also see that Eudoxus and MUL.APIN share a substantial number of observations. In all, some Assyrian observer(s) between 33-36 degrees north latitude around the time of 1300-1000 BC apparently invented many of the constellations adopted by the Greeks and made a database of observations later repeated by MUL.APIN, Eudoxus, Aratus, and Hipparchus. But this is not the whole story, as this only accounts for 19 Greek constellations which are identical in stars and representation with the Mesopotamian sky. An additional 12 Greek constellations have the same star groups as the Babylonians yet have completely different mythology/names; and so these representations must have been added by the Greeks. In addition, the Bear constellations must have originated with Paleolithic hunters in northern Eurasia sometime before 11,000 BC, as shown by the widespread distribution of essentially identical myths for the asterism across Eurasia and North America. This leaves about a dozen old constellations which have no Mesopotamian roots and for which the first reference anywhere is from early Greek sources and which have characteristically Greek flavor. Thus it appears that a substantial fraction of the old Greek constellations are actually Greek in origin, with the majority being older asterisms adopted from Mesopotamia, while the Bear originates at least 13,000 years ago. This research was supported in part by the Herbert C. Pollack Award of the Dudley Observatory.

Constellation Space Suit System Development Status

NASA Technical Reports Server (NTRS)

Ross, Amy; Aitchison, Lindsay; Daniel, Brian

2007-01-01

The Constellation Program has initiated the first new flight suit development project since the Extravehicular Mobility Unit (EMU) was developed for the Space Shuttle Program in the 1970s. The Constellation suit system represents a significant challenge to designers in that the system is required to address all space suit functions needed through all missions and mission phases. This is in marked contrast to the EMU, which was designed specifically for micro-gravity space walks. The Constellation suit system must serve in all of the following scenarios: launch, entry and abort crew survival; micro-gravity extravehicular activity (EVA); and lunar (1/6th-gravity) surface EVA. This paper discusses technical efforts performed from May 2006 through February 2007 for the Constellation space suit system pressure garment.

The HUMSAT System: a CubeSat-based Constellation for In-situ and Inexpensive Environmental Measurements

NASA Astrophysics Data System (ADS)

Tubío-Pardavila, R.; Vigil, S. A.; Puig-Suari, J.; Aguado Agelet, F.

2014-12-01

There is a requirement for low cost in-situ measurements of environmental parameters such as air quality, meteorological data, and water quality in remote areas. Currently available solutions for such measurements include remote sensing from satellite and aircraft platforms, and in-situ measurements from mobile and aircraft platforms. Fixed systems such as eddy covariance networks, tall towers, and the Total Carbon Column Observing Network (TCCON) are providing precision greenhouse gas measurements. Within this context, the HUMSAT system designed by the University of Vigo (Spain) will complement existing high-precision measurement systems with low cost in-situ ground based sensors in remote locations using a constellation of CubeSats as a communications relay. The HUMSAT system standardizes radio communications in between deployed sensors and the CubeSats of the constellation, which act as store and forward satellites to ground stations for uploading to the internet. Current ground stations have been established at the University of Vigo (Spain) and California Polytechnic State University (Cal Poly). Users of the system may deploy their own environmental sensors to meet local requirements. The sensors will be linked to a low-cost satellite data transceiver using a standard HUMSAT protocol. The transceiver is capable of receiving data from the HUMSAT constellation to remotely reconfigure sensors without the need of physically going to the sensor location. This transceiver uses a UHF channel around 437 MHz to exchange short data messages with the sensors. These data messages can contain up to 32 bytes of useful information and are transmitted at a speed around 300 bps. The protocol designed for this system handles the access to the channel by all these elements and guarantees a correct transmission of the information in such an scenario. The University of Vigo has launched the first satellite of the constellation, the HUMSAT-D CubeSat in November 2013 and has deployed sensors in Spain and Brazil. Sensors will be also deployed by Cal Poly in the near future. In the following months, the SERPENS CubeSAT Mission, a joint project of the University of Brasilia and the University of Vigo will launch the second CubeSat of the constellation.

Constellation Program Human-System Integration Requirements. Revision E, Nov. 19, 2010

NASA Technical Reports Server (NTRS)

Dory, Jonathan

2010-01-01

The Human-Systems Integration Requirements (HSIR) in this document drive the design of space vehicles, their systems, and equipment with which humans interface in the Constellation Program (CxP). These requirements ensure that the design of Constellation (Cx) systems is centered on the needs, capabilities, and limitations of the human. The HSIR provides requirements to ensure proper integration of human-to-system interfaces. These requirements apply to all mission phases, including pre-launch, ascent, Earth orbit, trans-lunar flight, lunar orbit, lunar landing, lunar ascent, Earth return, Earth entry, Earth landing, post-landing, and recovery. The Constellation Program must meet NASA's Agency-level human rating requirements, which are intended to ensure crew survival without permanent disability. The HSIR provides a key mechanism for achieving human rating of Constellation systems.

Methodology and Method and Apparatus for Signaling With Capacity Optimized Constellations

NASA Technical Reports Server (NTRS)

Barsoum, Maged F. (Inventor); Jones, Christopher R. (Inventor)

2014-01-01

Communication systems are described that use geometrically shaped constellations that have increased capacity compared to conventional constellations operating within a similar SNR band. In several embodiments, the geometrically shaped is optimized based upon a capacity measure such as parallel decoding capacity or joint capacity. In many embodiments, a capacity optimized geometrically shaped constellation can be used to replace a conventional constellation as part of a firmware upgrade to transmitters and receivers within a communication system. In a number of embodiments, the geometrically shaped constellation is optimized for an Additive White Gaussian Noise channel or a fading channel. In numerous embodiments, the communication uses adaptive rate encoding and the location of points within the geometrically shaped constellation changes as the code rate changes.

Advanced platform technologies for Earth science

NASA Astrophysics Data System (ADS)

Lemmerman, Loren; Raymond, Carol; Shotwell, Robert; Chase, James; Bhasin, Kul; Connerton, Robert

2005-01-01

Historically, Earth science investigations have been independent and highly focused. However, the Earth's environment is a very dynamic and interrelated system and to understand it, significant improvements in spatial and temporal observations will be required. Science needs to document the need for constellations to achieve desired spatial and temporal observations. A key element envisioned for accomplishing these difficult challenges is the idea of a distributed, heterogeneous, and adaptive observing system or sensor web. This paper focuses on one possible approach based on a LEO constellation composed of 100 spacecraft. A cost analysis has been done to indicate the financial pressures of each mission phase and conclusions are drawn suggesting that new technology investments are needed, directed toward lowering production costs; that operations costs will need to be reduced through autonomy; and that, of the on-board subsystems considered, advanced power generation and management may be the most enabling of new technologies.

VISTA - A Constellation for Real Time Regional Imaging

NASA Astrophysics Data System (ADS)

Meerman, Max; Boland, Lee; da Silva Curiel, Alex; Sweeting, Martin, , Sir

2002-01-01

The role of satellites in medium and high-resolution reconnaissance of the Earth's surface has been well demonstrated in recent years through missions such as Landsat, SPOT, IKONOS, ImageSat and Quickbird. The market for such data products is well served and likely to become more competitive with further very-high-resolution missions. Whereas commercial markets have concentrated on enhancing resolution, the small satellite sector has concentrated on reducing the cost of data products, and the development of systems providing niche services. One such EO requirement that can be well met by smaller satellites is the need for higher temporal resolution, as this typically requires a large number of satellites to operate as a constellation - thus far financially impractical using conventional EO satellites. Surrey is currently engaged in building its first constellation that will provide daily global coverage at moderate resolution (32-metre GSD and 600km swath) in three spectral bands. Targeted at providing timely quick-look data products for disaster mitigation and monitoring, the constellation comprises 7 satellites in a single orbital plane. Each satellite has a wide swath so that successive satellites progressively cover the entire globe in a single day. The Vista constellation takes this concept a step further, and is proposed for applications requiring near-continuous surveillance of regional activity. By introducing a multiple plane constellation of small Earth observation satellites, it is possible to monitor continuously selected regions anywhere on the globe. The paper describes the system trades and outlines the scope of the performance that could be obtained from such a system. A cost model illustrates that the balance between launch and space segment costs must be reached by considering suitable replacement strategies, and that the system is highly sensitive to requirement creep. Finally, it is shown that the use of cost effective, small satellites leads to solutions previously thought to be financially beyond sensible reach.

A possible space VLBI constellation utilizing the stable orbits around the TLPs in the Earth-Moon system.

NASA Astrophysics Data System (ADS)

Liu, Bin; Tang, Jingshi; Hou, Xiyun

2016-07-01

Current studies indicate that there are stable orbits around but far away from the triangular libration points .Two special quasi-periodic orbits around each triangular libration points L4 , L5 in the Earth-Moon sys-tem perturbed by Sun are gain , and the stable orbits discussed in this work are ideal places for space colonies because no orbit control is needed. These stable orbits can also be used as nominal orbits for space VLBI (Very Long Baseline Interferometry) stations. The two stations can also form baselines with stations on the Earth and the Moon, or with stations located around another TLP. Due to the long distance between the stations, the observation precision can be greatly enhanced compared with the VLBI stations on the Earth. Such a VLBI constellation not only can advance the radio astronomy, but also can be used as a navigation system for human activities in the Earth-Moon system and even in the solar system. This paper will focus on the navigation constellation coverage issues, and the orbit determination accuracy problems within the Earth-Moon sys-tem and interplanetary space.

Real-time Retrieving Atmospheric Parameters from Multi-GNSS Constellations

NASA Astrophysics Data System (ADS)

Li, X.; Zus, F.; Lu, C.; Dick, G.; Ge, M.; Wickert, J.; Schuh, H.

2016-12-01

The multi-constellation GNSS (e.g. GPS, GLONASS, Galileo, and BeiDou) bring great opportunities and challenges for real-time retrieval of atmospheric parameters for supporting numerical weather prediction (NWP) nowcasting or severe weather event monitoring. In this study, the observations from different GNSS are combined together for atmospheric parameter retrieving based on the real-time precise point positioning technique. The atmospheric parameters retrieved from multi-GNSS observations, including zenith total delay (ZTD), integrated water vapor (IWV), horizontal gradient (especially high-resolution gradient estimates) and slant total delay (STD), are carefully analyzed and evaluated by using the VLBI, radiosonde, water vapor radiometer and numerical weather model to independently validate the performance of individual GNSS and also demonstrate the benefits of multi-constellation GNSS for real-time atmospheric monitoring. Numerous results show that the multi-GNSS processing can provide real-time atmospheric products with higher accuracy, stronger reliability and better distribution, which would be beneficial for atmospheric sounding systems, especially for nowcasting of extreme weather.

Temporal Experiment for Storms and Tropical Systems (TEMPEST) CubeSat Constellation

NASA Astrophysics Data System (ADS)

Reising, S. C.; Todd, G.; Padmanabhan, S.; Brown, S. T.; Lim, B.; Kummerow, C. D.; Chandra, C. V.; van den Heever, S. C.; L'Ecuyer, T. S.; Luo, Z. J.; Haddad, Z. S.; Munchak, S. J.; Ruf, C. S.; Berg, G.; Koch, T.; Boukabara, S. A.

2014-12-01

TEMPEST addresses key science needs related to cloud and precipitation processes using a constellation of five CubeSats with identical five-frequency millimeter-wave radiometers spaced 5-10 minutes apart in orbit. The deployment of CubeSat constellations on satellite launches of opportunity allows Earth system observations to be accomplished with greater robustness, shorter repeat times and at a small fraction of the cost of typical Earth Science missions. The current suite of Earth-observing satellites is capable of measuring precipitation parameters using radar or radiometric observations. However, these low Earth-orbiting satellites provide only a snapshot of each storm, due to their repeat-pass times of many hours to days. With typical convective events lasting 1-2 hours, it is highly unlikely that the time evolution of clouds through the onset of precipitation will be observed with current assets. The TEMPEST CubeSat constellation directly observes the time evolution of clouds and identifies changes in time to detect the moment of the onset of precipitation. The TEMPEST millimeter-wave radiometers penetrate into the cloud to directly observe changes as the cloud begins to precipitate or ice accumulates inside the storm. The evolution of ice formation in clouds is important for climate prediction because it largely drives Earth's radiation budget. TEMPEST improves understanding of cloud processes and helps to constrain one of the largest sources of uncertainty in climate models. TEMPEST provides observations at five millimeter-wave frequencies from 90 to 183 GHz using a single compact instrument that is well suited for a 6U CubeSat architecture and fits well within the NASA CubeSat Launch Initiative (CSLI) capabilities. Five identical CubeSats deployed in the same orbital plane with 5-10 minute spacing at 390-450 km altitude and 50-65 degree inclination capture 3 million observations of precipitation, including 100,000 deep convective events in a one-year mission. TEMPEST provides critical information on the time evolution of cloud and precipitation microphysics, thereby yielding a first-order understanding of how assumptions in current cloud-model parameterizations behave in diverse climate regimes.

Human Systems Integration (HSI) Case Studies from the NASA Constellation Program

NASA Technical Reports Server (NTRS)

Baggerman, Susan; Berdich, Debbie; Whitmore, Mihriban

2009-01-01

The National Aeronautics and Space Administration (NASA) Constellation Program is responsible for planning and implementing those programs necessary to send human explorers back to the moon, onward to Mars and other destinations in the solar system, and to support missions to the International Space Station. The Constellation Program has the technical management responsibility for all Constellation Projects, including both human rated and non-human rated vehicles such as the Crew Exploration Vehicle, EVA Systems, the Lunar Lander, Lunar Surface Systems, and the Ares I and Ares V rockets. With NASA s new Vision for Space Exploration to send humans beyond Earth orbit, it is critical to consider the human as a system that demands early and continuous user involvement, inclusion in trade offs and analyses, and an iterative "prototype/test/ redesign" process. Personnel at the NASA Johnson Space Center are involved in the Constellation Program at both the Program and Project levels as human system integrators. They ensure that the human is considered as a system, equal to hardware and software vehicle systems. Systems to deliver and support extended human habitation on the moon are extremely complex and unique, presenting new opportunities to employ Human Systems Integration, or HSI practices in the Constellation Program. The purpose of the paper is to show examples of where human systems integration work is successfully employed in the Constellation Program and related Projects, such as in the areas of habitation and early requirements and design concepts.

Hidden topological constellations and polyvalent charges in chiral nematic droplets

NASA Astrophysics Data System (ADS)

Posnjak, Gregor; Čopar, Simon; Muševič, Igor

2017-02-01

Topology has an increasingly important role in the physics of condensed matter, quantum systems, material science, photonics and biology, with spectacular realizations of topological concepts in liquid crystals. Here we report on long-lived hidden topological states in thermally quenched, chiral nematic droplets, formed from string-like, triangular and polyhedral constellations of monovalent and polyvalent singular point defects. These topological defects are regularly packed into a spherical liquid volume and stabilized by the elastic energy barrier due to the helical structure and confinement of the liquid crystal in the micro-sphere. We observe, for the first time, topological three-dimensional point defects of the quantized hedgehog charge q=-2, -3. These higher-charge defects act as ideal polyvalent artificial atoms, binding the defects into polyhedral constellations representing topological molecules.

Hidden topological constellations and polyvalent charges in chiral nematic droplets

PubMed Central

Posnjak, Gregor; Čopar, Simon; Muševič, Igor

2017-01-01

Topology has an increasingly important role in the physics of condensed matter, quantum systems, material science, photonics and biology, with spectacular realizations of topological concepts in liquid crystals. Here we report on long-lived hidden topological states in thermally quenched, chiral nematic droplets, formed from string-like, triangular and polyhedral constellations of monovalent and polyvalent singular point defects. These topological defects are regularly packed into a spherical liquid volume and stabilized by the elastic energy barrier due to the helical structure and confinement of the liquid crystal in the micro-sphere. We observe, for the first time, topological three-dimensional point defects of the quantized hedgehog charge q=−2, −3. These higher-charge defects act as ideal polyvalent artificial atoms, binding the defects into polyhedral constellations representing topological molecules. PMID:28220770

Making every gram count - Big measurements from tiny platforms (Invited)

NASA Astrophysics Data System (ADS)

Fish, C. S.; Neilsen, T. L.; Stromberg, E. M.

2013-12-01

The most significant advances in Earth, solar, and space physics over the next decades will originate from new, system-level observational techniques. The most promising technique to still be fully developed and exploited requires conducting multi-point or distributed constellation-based observations. This system-level observational approach is required to understand the 'big picture' coupling between disparate regions such as the solar-wind, magnetosphere, ionosphere, upper atmosphere, land, and ocean. The national research council, NASA science mission directorate, and the larger heliophysics community have repeatedly identified the pressing need for multipoint scientific investigations to be implemented via satellite constellations. The NASA Solar Terrestrial Probes Magnetospheric Multiscale (MMS) mission and NASA Earth Science Division's 'A-train', consisting of the AQUA, CloudSat, CALIPSO and AURA satellites, are examples of such constellations. However, the costs to date of these and other similar proposed constellations have been prohibitive given the 'large satellite' architectures and the multiple launch vehicles required for implementing the constellations. Financially sustainable development and deployment of multi-spacecraft constellations can only be achieved through the use of small spacecraft that allow for multiple hostings per launch vehicle. The revolution in commercial mobile and other battery powered consumer technology has helped enable researchers in recent years to build and fly very small yet capable satellites, principally CubeSats. A majority of the CubeSat activity and development to date has come from international academia and the amateur radio satellite community, but several of the typical large-satellite vendors have developed CubeSats as well. Recent government-sponsored CubeSat initiatives, such as the NRO Colony, NSF CubeSat Space Weather, NASA Office of Chief Technologist Edison and CubeSat Launch Initiative (CSLI) Educational Launch of Nanosatellites Educational Launch of Nano-satellites (ELaNa), the Air Force Space Environmental NanoSat Experiment (SENSE), and the ESA QB50 programs have spurred the development of very proficient miniature space sensors and technologies that enable technology demonstration, space and earth science research, and operational CubeSat based missions. In this paper we will review many of the small, low cost sensor and instrumentation technologies that have been developed to date as part of the CubeSat movement and examine how these new CubeSat based technologies are helping us do more with less.

Using CYGNSS to Observe Convectively Driven Near-Surface Winds in Tropical Precipitation Systems During Madden-Julian Oscillation Events

NASA Technical Reports Server (NTRS)

Lang, Timothy J.; Li, Xuanli; Mecikalski, John; Hoover, Kacie; Castillo, Tyler; Chronis, Themis

2017-01-01

The Cyclone Global Navigation OKLMA 1411 UTC Satellite System (CYGNSS) is a multi-satellite constellation that launched 15 December 2016. The primary objective of CYGNSS is to use bistatic Global Positioning System (GPS) reflectometry to accurately measure near-surface wind speeds within the heavily raining inner core of tropical cyclones. CYGNSS also features rapid revisit times over a given region in the tropics - ranging from several minutes to a few hours, depending on the constellation geometry at that time. Despite the focus on tropical cyclones, the ability of CYGNSS to provide rapid updates of winds, unbiased by the presence of precipitation, has many other potential applications related to general tropical convection.

International Earth Science Constellation Mission Operations Working Group: Constellation Coordination System (CCS) Status. [Constellation Coordination System (CCS) Status

NASA Technical Reports Server (NTRS)

Skeberdis, Daniel

2016-01-01

This is a presentation at the MOWG fall meeting that will discuss CCS purpose, future status, security enhancements, arbitrary ephemeris mission features, overview of CCS 7.3, approach for the use of NORAD TLEs, account and data security, CCS System virtualization, control box visualization modification and other enhancements.

Precise positioning with current multi-constellation Global Navigation Satellite Systems: GPS, GLONASS, Galileo and BeiDou.

PubMed

Li, Xingxing; Zhang, Xiaohong; Ren, Xiaodong; Fritsche, Mathias; Wickert, Jens; Schuh, Harald

2015-02-09

The world of satellite navigation is undergoing dramatic changes with the rapid development of multi-constellation Global Navigation Satellite Systems (GNSSs). At the moment more than 70 satellites are already in view, and about 120 satellites will be available once all four systems (BeiDou + Galileo + GLONASS + GPS) are fully deployed in the next few years. This will bring great opportunities and challenges for both scientific and engineering applications. In this paper we develop a four-system positioning model to make full use of all available observations from different GNSSs. The significant improvement of satellite visibility, spatial geometry, dilution of precision, convergence, accuracy, continuity and reliability that a combining utilization of multi-GNSS brings to precise positioning are carefully analyzed and evaluated, especially in constrained environments.

2016 Mission Operations Working Group: Earth Observing-1 (EO-1)

NASA Technical Reports Server (NTRS)

Frye, Stuart

2016-01-01

EO-1 Mission Status for the Constellation Mission Operations Working Group to discuss the EO-1 flight systems, mission enhancements, debris avoidance maneuver, orbital information, 5-year outlook, and new ground stations.

Design and implementation of satellite formations and constellations

NASA Technical Reports Server (NTRS)

Folta, David; Newman, Lauri Kraft; Quinn, David

1998-01-01

The direction to develop small low cost spacecraft has led many scientists to recognize the advantage of flying spacecraft in constellations and formations to achieve the correlated instrument measurements formerly possible only by flying many instruments on a single large platform. Yet, constellations and formation flying impose additional complications on orbit selection and orbit maintenance, especially when each spacecraft has its own orbit or science requirements. The purpose of this paper is to develop an operational control method for maintenance of these missions. Examples will be taken from the Earth Observing-1 (EO-1) spacecraft that is part of the New Millennium Program (NMP) and from proposed Earth System Science Program Office (ESSPO) constellations. Results can be used to determine the appropriateness of constellations and formation flying for a particular case as well as the operational impacts. Applications to the ESSPO and NMP are highly considered in analysis and applications. After constellation and formation analysis is completed, implementation of a maneuver maintenance strategy becomes the driver. Advances in technology and automation by GSFC's Guidance, Navigation, and Control Center allow more of the burden of the orbit selection and maneuver maintenance to be automated and ultimately placed onboard the spacecraft, mitigating most of the associated operational concerns. This paper presents the GSFC closed-loop control method to fly in either constellations or formations through the use of an autonomous closed loop three-axis navigation control and innovative orbit maintenance support. Simulation results using AutoCon(TM) and FreeFlyer(TM) with various fidelity levels of modeling and algorithms are presented.

Design and Implementation of Satellite Formations and Constellations

NASA Technical Reports Server (NTRS)

Folta, David; Newman, Lauri Kraft; Quinn, David

1998-01-01

The direction to develop small low cost spacecraft has led many scientists to recognize the advantage of flying spacecraft in constellations and formations to achieve the correlated instrument measurements formerly possible only by flying many instruments on a single large platform. Yet, constellations and formation flying impose additional complications on orbit selection and orbit maintenance, especially when each spacecraft has its own orbit or science requirements. The purpose of this paper is to develop an operational control method for maintenance of these missions. Examples will be taken from the Earth Observing-1 (EO-1) spacecraft that is part of the New Millennium Program (NMP) and from proposed Earth System Science Program Office (ESSPO) constellations. Results can be used to determine the appropriateness of constellations and formation flying for a particular case as well as the operational impacts. Applications to the ESSPO and NMP are highly considered in analysis and applications. After constellation and formation analysis is completed, implementation of a maneuver maintenance strategy becomes the driver. Advances in technology and automation by GSFC's Guidance, Navigation, and Control Center allow more of the burden of the orbit selection and maneuver maintenance to be automated and ultimately placed onboard the spacecraft, mitigating most of the associated operational concerns. This paper presents the GSFC closed-loop control method to fly in either constellations or formations through the use of an autonomous closed loop three-axis navigation control and innovative orbit maintenance support. Simulation results using AutoCon(Trademark) and FreeFlyer(Trademark) with various fidelity levels of modeling and algorithms are presented.

A Constellation of Microsatellites Promises to Help in a Range of Geoscience Research

NASA Technical Reports Server (NTRS)

Kuo, Y. H.; Chao, B. F.; Lee, L. C.

1999-01-01

An octet of microsatellites to be launched in 2003 promises to deliver a large amount of useful data for meteorological, climatic, ionospheric, and geodetic research as well as for operational weather forecasting and space weather monitoring. Known as the Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC), the joint Taiwan-U.S. scientific satellite project makes use of Global Positioning System (GPS) occultation and tracking signals. COSMIC's final operational configuration is depicted in Figure 1. Each of the eight microsatellites in low-Earth-orbit (LEO, shown relative to the high-altitude GPS satellite orbits) will carry in particular an advanced limb-sounding GPS receiver, a Tiny Ionospheric Photometer, and a triband beacon transmitter.

Teaching through Trade Books: Seeing Stars

ERIC Educational Resources Information Center

Royce, Christine Anne

2008-01-01

The winter months are a great time to make observations of several familiar constellations. While there is no scientific reason to "know" the constellations--they are simply imaginative pictures imposed on stars--studying constellations can help students connect with culture in a fun way and develop the awareness that stars are different in…

Adaptation and Re-Use of Spacecraft Power System Models for the Constellation Program

NASA Technical Reports Server (NTRS)

Hojnicki, Jeffrey S.; Kerslake, Thomas W.; Ayres, Mark; Han, Augustina H.; Adamson, Adrian M.

2008-01-01

NASA's Constellation Program is embarking on a new era of space exploration, returning to the Moon and beyond. The Constellation architecture will consist of a number of new spacecraft elements, including the Orion crew exploration vehicle, the Altair lunar lander, and the Ares family of launch vehicles. Each of these new spacecraft elements will need an electric power system, and those power systems will need to be designed to fulfill unique mission objectives and to survive the unique environments encountered on a lunar exploration mission. As with any new spacecraft power system development, preliminary design work will rely heavily on analysis to select the proper power technologies, size the power system components, and predict the system performance throughout the required mission profile. Constellation projects have the advantage of leveraging power system modeling developments from other recent programs such as the International Space Station (ISS) and the Mars Exploration Program. These programs have developed mature power system modeling tools, which can be quickly modified to meet the unique needs of Constellation, and thus provide a rapid capability for detailed power system modeling that otherwise would not exist.

Nanosatellite Architectures for Improved Study of the Hydrologic Cycle

NASA Astrophysics Data System (ADS)

Blackwell, W. J.; Osaretin, I.; Cahoy, K.

2012-12-01

The need for low-cost, mission-flexible, and rapidly deployable spaceborne sensors that meet stringent performance requirements pervades the NASA Earth Science measurement programs, including especially the recommended NRC Decadal Survey missions. To address these challenges, we present nanosatellite constellation architectures that would profoundly improve both the performance and cost/risk/schedule profiles of NASA Earth and Space Science missions by leveraging recent technology advancements. As a key enabling element, we describe a scalable and mission-flexible 6U CubeSat-based self-organizing constellation architecture (the Distributed Observatory for Monitoring of Earth, henceforth "DOME") that will achieve state-of-the-art performance (and beyond) relative to current systems with respect to spatial, spectral, and radiometric resolution. A focus of this presentation is an assessment of the viability of a cross-linked CubeSat constellation with onboard propulsion systems for high-fidelity Earth and Space Science research. Such architecture could provide game-changing advances by reducing costs by at least an order of magnitude while increasing robustness to launch and sensor failures, allowing fast-track insertion of new technologies, and improving science performance. High-resolution passive microwave atmospheric sounding is an ideal sensing modality for nanosatellite implementation due to rapidly advancing microwave and millimeterwave receiver technology. The DOME constellation would nominally comprise 6U CubeSat Microwave Atmospheric Sounder (CMAS) satellites. Each CMAS satellite would host a complete 6U CubeSat atmospheric sounder, including a radiometer payload module with passive microwave receivers operating near atmospheric absorption lines near 60 and 183.31 GHz, and a spacecraft bus with attitude determination and control, avionics, power, cross-linked communications (spacecraft-to-spacecraft and spacecraft-to-ground), and propulsion systems. A spacecraft spinning mechanism provides a 60 RPM cross-track scan as the satellite orbits the earth. Spatial, spectral, and radiometric performance is comparable to present state-of-the-art systems with costs exceeding $100M. The propulsion systems would be used to achieve formation flight (the satellites would be separated by approximately 500 ± 5 km) and to facilitate de-orbit. The cross-linked communication would provide: 1) reduced communications latency to ground, a key performance attribute that is currently lacking in present systems leading to suboptimal utilization of observations of dynamic meteorological events such as tropical cyclones and hurricanes, and 2) data-driven sensing whereby the lead sensor observes dynamic meteorological phenomena and sends a message to the following sensor to temporarily enable a very high resolution sensing mode (a higher sample rate, for example) to better capture the interesting event and preserve spacecraft resources for when they are most needed. The DOME constellation would allow global, high-resolution, persistent observations of the Earth's surface and atmosphere for studies of the hydrologic cycle and climate feedback processes.

Autonomous Scheduling Requirements for Agile Cubesat Constellations in Earth Observation

NASA Astrophysics Data System (ADS)

Nag, S.; Li, A. S. X.; Kumar, S.

2017-12-01

Distributed Space Missions such as formation flight and constellations, are being recognized as important Earth Observation solutions to increase measurement samples over space and time. Cubesats are increasing in size (27U, 40 kg) with increasing capabilities to host imager payloads. Given the precise attitude control systems emerging commercially, Cubesats now have the ability to slew and capture images within short notice. Prior literature has demonstrated a modular framework that combines orbital mechanics, attitude control and scheduling optimization to plan the time-varying orientation of agile Cubesats in a constellation such that they maximize the number of observed images, within the constraints of hardware specs. Schedule optimization is performed on the ground autonomously, using dynamic programming with two levels of heuristics, verified and improved upon using mixed integer linear programming. Our algorithm-in-the-loop simulation applied to Landsat's use case, captured up to 161% more Landsat images than nadir-pointing sensors with the same field of view, on a 2-satellite constellation over a 12-hour simulation. In this paper, we will derive the requirements for the above algorithm to run onboard small satellites such that the constellation can make time-sensitive decisions to slew and capture images autonomously, without ground support. We will apply the above autonomous algorithm to a time critical use case - monitoring of precipitation and subsequent effects on floods, landslides and soil moisture, as quantified by the NASA Unified Weather Research and Forecasting Model. Since the latency between these event occurrences is quite low, they make a strong case for autonomous decisions among satellites in a constellation. The algorithm can be implemented in the Plan Execution Interchange Language - NASA's open source technology for automation, used to operate the International Space Station and LADEE's in flight software - enabling a controller-in-the-loop demonstration. The autonomy software can then be integrated with NASA's open source Core Flight Software, ported onto a Raspberry Pi 3.0 for a software-in-the-loop demonstration. Future use cases can be time critical events such as cloud movement, storms or other disasters, and in conjunction with other platforms in a Sensor Web.

Precise positioning with current multi-constellation Global Navigation Satellite Systems: GPS, GLONASS, Galileo and BeiDou

PubMed Central

Li, Xingxing; Zhang, Xiaohong; Ren, Xiaodong; Fritsche, Mathias; Wickert, Jens; Schuh, Harald

2015-01-01

The world of satellite navigation is undergoing dramatic changes with the rapid development of multi-constellation Global Navigation Satellite Systems (GNSSs). At the moment more than 70 satellites are already in view, and about 120 satellites will be available once all four systems (BeiDou + Galileo + GLONASS + GPS) are fully deployed in the next few years. This will bring great opportunities and challenges for both scientific and engineering applications. In this paper we develop a four-system positioning model to make full use of all available observations from different GNSSs. The significant improvement of satellite visibility, spatial geometry, dilution of precision, convergence, accuracy, continuity and reliability that a combining utilization of multi-GNSS brings to precise positioning are carefully analyzed and evaluated, especially in constrained environments. PMID:25659949

An Approach to Speed up Single-Frequency PPP Convergence with Quad-Constellation GNSS and GIM.

PubMed

Cai, Changsheng; Gong, Yangzhao; Gao, Yang; Kuang, Cuilin

2017-06-06

The single-frequency precise point positioning (PPP) technique has attracted increasing attention due to its high accuracy and low cost. However, a very long convergence time, normally a few hours, is required in order to achieve a positioning accuracy level of a few centimeters. In this study, an approach is proposed to accelerate the single-frequency PPP convergence by combining quad-constellation global navigation satellite system (GNSS) and global ionospheric map (GIM) data. In this proposed approach, the GPS, GLONASS, BeiDou, and Galileo observations are directly used in an uncombined observation model and as a result the ionospheric and hardware delay (IHD) can be estimated together as a single unknown parameter. The IHD values acquired from the GIM product and the multi-GNSS differential code bias (DCB) product are then utilized as pseudo-observables of the IHD parameter in the observation model. A time varying weight scheme has also been proposed for the pseudo-observables to gradually decrease its contribution to the position solutions during the convergence period. To evaluate the proposed approach, datasets from twelve Multi-GNSS Experiment (MGEX) stations on seven consecutive days are processed and analyzed. The numerical results indicate that the single-frequency PPP with quad-constellation GNSS and GIM data are able to reduce the convergence time by 56%, 47%, 41% in the east, north, and up directions compared to the GPS-only single-frequency PPP.

Constellation Ground Systems Launch Availability Analysis: Enhancing Highly Reliable Launch Systems Design

NASA Technical Reports Server (NTRS)

Gernand, Jeffrey L.; Gillespie, Amanda M.; Monaghan, Mark W.; Cummings, Nicholas H.

2010-01-01

Success of the Constellation Program's lunar architecture requires successfully launching two vehicles, Ares I/Orion and Ares V/Altair, in a very limited time period. The reliability and maintainability of flight vehicles and ground systems must deliver a high probability of successfully launching the second vehicle in order to avoid wasting the on-orbit asset launched by the first vehicle. The Ground Operations Project determined which ground subsystems had the potential to affect the probability of the second launch and allocated quantitative availability requirements to these subsystems. The Ground Operations Project also developed a methodology to estimate subsystem reliability, availability and maintainability to ensure that ground subsystems complied with allocated launch availability and maintainability requirements. The verification analysis developed quantitative estimates of subsystem availability based on design documentation; testing results, and other information. Where appropriate, actual performance history was used for legacy subsystems or comparative components that will support Constellation. The results of the verification analysis will be used to verify compliance with requirements and to highlight design or performance shortcomings for further decision-making. This case study will discuss the subsystem requirements allocation process, describe the ground systems methodology for completing quantitative reliability, availability and maintainability analysis, and present findings and observation based on analysis leading to the Ground Systems Preliminary Design Review milestone.

New Opportunities in Geospace Remote Sensing

NASA Astrophysics Data System (ADS)

Solomon, S. C.

2017-12-01

This paper will discuss scientific objectives that can be addressed with the serendipitous constellation of thermosphere-ionosphere observations provided by the NASA Ionospheric Connection Explorer (ICON) and Global-scale Observations of the Limb and Disk (GOLD) missions, the international Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC-2), instruments on the International Space Station and the Defense Meteorological Satellite Program, the European SWARM satellites, the NSF-sponsored AMPERE project, and the ongoing TIMED mission. The confluence of these space-based observations provide opportunities to extend the capabilities of ground-based observational networks, and to exploit opportunities for the development of numerical models and data assimilation methods. A particular focus is the global-scale context provided through GOLD mission measurements, and the challenges presented by their analysis and interpretation. GOLD can be considered a pathfinder for opportunistic instrumentation on commercial vehicles at geostationary orbit, so further speculation will be presented on what other future observations of the thermosphere-ionosphere and exosphere-plasmasphere could be made from these platforms.

On the Feasibility of Monitoring Carbon Monoxide in the Lower Troposphere from a Constellation of Northern Hemisphere Geostationary Satellites (PART 1)

NASA Technical Reports Server (NTRS)

Barre, Jerome; Edwards, David; Worden, Helen; Da Silva, Arlindo; Lahoz, William

2015-01-01

By the end of the current decade, there are plans to deploy several geostationary Earth orbit (GEO) satellite missions for atmospheric composition over North America, East Asia and Europe with additional missions proposed. Together, these present the possibility of a constellation of geostationary platforms to achieve continuous time-resolved high-density observations over continental domains for mapping pollutant sources and variability at diurnal and local scales. In this paper, we use a novel approach to sample a very high global resolution model (GEOS-5 at 7 km horizontal resolution) to produce a dataset of synthetic carbon monoxide pollution observations representative of those potentially obtainable from a GEO satellite constellation with predicted measurement sensitivities based on current remote sensing capabilities. Part 1 of this study focuses on the production of simulated synthetic measurements for air quality OSSEs (Observing System Simulation Experiments). We simulate carbon monoxide nadir retrievals using a technique that provides realistic measurements with very low computational cost. We discuss the sampling methodology: the projection of footprints and areas of regard for geostationary geometries over each of the North America, East Asia and Europe regions; the regression method to simulate measurement sensitivity; and the measurement error simulation. A detailed analysis of the simulated observation sensitivity is performed, and limitations of the method are discussed. We also describe impacts from clouds, showing that the efficiency of an instrument making atmospheric composition measurements on a geostationary platform is dependent on the dominant weather regime over a given region and the pixel size resolution. These results demonstrate the viability of the "instrument simulator" step for an OSSE to assess the performance of a constellation of geostationary satellites for air quality measurements.

New Science Enabled by the NASA TROPICS CubeSat Constellation Mission

NASA Astrophysics Data System (ADS)

Blackwell, W. J.; Braun, S. A.; Bennartz, R.; Velden, C.; Demaria, M.; Atlas, R. M.; Dunion, J. P.; Marks, F.; Rogers, R. F.; Annane, B.

2017-12-01

Recent technology advances in miniature microwave radiometers that can be hosted on very small satellites has made possible a new class of affordable constellation missions that provide very high revisit rates of tropical cyclones and other severe weather. The Time-Resolved Observations of Precipitation structure and storm Intensity with a Constellation of Smallsats (TROPICS) mission was selected by NASA as part of the Earth Venture-Instrument (EVI-3) program and is now in development with planned launch readiness in late 2019. The overarching goal for TROPICS is to provide nearly all-weather observations of 3-D temperature and humidity, as well as cloud ice and precipitation horizontal structure, at high temporal resolution to conduct high-value science investigations of tropical cyclones, including: (1) relationships of rapidly evolving precipitation and upper cloud structures to upper-level warm-core intensity and associated storm intensity changes; (2) the evolution of precipitation structure and storm intensification in relationship to environmental humidity fields; and (3) the impact of rapid-update observations on numerical and statistical intensity forecasts of tropical cyclones. TROPICS will provide rapid-refresh microwave measurements (median refresh rate better than 60 minutes for the baseline mission) over the tropics that can be used to observe the thermodynamics of the troposphere and precipitation structure for storm systems at the mesoscale and synoptic scale over the entire storm lifecycle. TROPICS comprises a constellation of six CubeSats in three low-Earth orbital planes. Each CubeSat will host a high performance radiometer to provide temperature profiles using seven channels near the 118.75 GHz oxygen absorption line, water vapor profiles using 3 channels near the 183 GHz water vapor absorption line, imagery in a single channel near 90 GHz for precipitation measurements (when combined with higher resolution water vapor channels), and a single channel at 206 GHz that is more sensitive to precipitation-sized ice particles. This observing system offers an unprecedented combination of horizontal and temporal resolution to measure environmental and inner-core conditions for tropical cyclones on a nearly global scale.

A Survey of Cost Estimating Methodologies for Distributed Spacecraft Missions

NASA Technical Reports Server (NTRS)

Foreman, Veronica; Le Moigne, Jacqueline; de Weck, Oliver

2016-01-01

Satellite constellations present unique capabilities and opportunities to Earth orbiting and near-Earth scientific and communications missions, but also present new challenges to cost estimators. An effective and adaptive cost model is essential to successful mission design and implementation, and as Distributed Spacecraft Missions (DSM) become more common, cost estimating tools must become more representative of these types of designs. Existing cost models often focus on a single spacecraft and require extensive design knowledge to produce high fidelity estimates. Previous research has examined the shortcomings of existing cost practices as they pertain to the early stages of mission formulation, for both individual satellites and small satellite constellations. Recommendations have been made for how to improve the cost models for individual satellites one-at-a-time, but much of the complexity in constellation and DSM cost modeling arises from constellation systems level considerations that have not yet been examined. This paper constitutes a survey of the current state-of-the-art in cost estimating techniques with recommendations for improvements to increase the fidelity of future constellation cost estimates. To enable our investigation, we have developed a cost estimating tool for constellation missions. The development of this tool has revealed three high-priority weaknesses within existing parametric cost estimating capabilities as they pertain to DSM architectures: design iteration, integration and test, and mission operations. Within this paper we offer illustrative examples of these discrepancies and make preliminary recommendations for addressing them. DSM and satellite constellation missions are shifting the paradigm of space-based remote sensing, showing promise in the realms of Earth science, planetary observation, and various heliophysical applications. To fully reap the benefits of DSM technology, accurate and relevant cost estimating capabilities must exist; this paper offers insights critical to the future development and implementation of DSM cost estimating tools.

A Survey of Cost Estimating Methodologies for Distributed Spacecraft Missions

NASA Technical Reports Server (NTRS)

Foreman, Veronica L.; Le Moigne, Jacqueline; de Weck, Oliver

2016-01-01

Satellite constellations present unique capabilities and opportunities to Earth orbiting and near-Earth scientific and communications missions, but also present new challenges to cost estimators. An effective and adaptive cost model is essential to successful mission design and implementation, and as Distributed Spacecraft Missions (DSM) become more common, cost estimating tools must become more representative of these types of designs. Existing cost models often focus on a single spacecraft and require extensive design knowledge to produce high fidelity estimates. Previous research has examined the limitations of existing cost practices as they pertain to the early stages of mission formulation, for both individual satellites and small satellite constellations. Recommendations have been made for how to improve the cost models for individual satellites one-at-a-time, but much of the complexity in constellation and DSM cost modeling arises from constellation systems level considerations that have not yet been examined. This paper constitutes a survey of the current state-of-theart in cost estimating techniques with recommendations for improvements to increase the fidelity of future constellation cost estimates. To enable our investigation, we have developed a cost estimating tool for constellation missions. The development of this tool has revealed three high-priority shortcomings within existing parametric cost estimating capabilities as they pertain to DSM architectures: design iteration, integration and test, and mission operations. Within this paper we offer illustrative examples of these discrepancies and make preliminary recommendations for addressing them. DSM and satellite constellation missions are shifting the paradigm of space-based remote sensing, showing promise in the realms of Earth science, planetary observation, and various heliophysical applications. To fully reap the benefits of DSM technology, accurate and relevant cost estimating capabilities must exist; this paper offers insights critical to the future development and implementation of DSM cost estimating tools.

Capacity Maximizing Constellations

NASA Technical Reports Server (NTRS)

Barsoum, Maged; Jones, Christopher

2010-01-01

Some non-traditional signal constellations have been proposed for transmission of data over the Additive White Gaussian Noise (AWGN) channel using such channel-capacity-approaching codes as low-density parity-check (LDPC) or turbo codes. Computational simulations have shown performance gains of more than 1 dB over traditional constellations. These gains could be translated to bandwidth- efficient communications, variously, over longer distances, using less power, or using smaller antennas. The proposed constellations have been used in a bit-interleaved coded modulation system employing state-ofthe-art LDPC codes. In computational simulations, these constellations were shown to afford performance gains over traditional constellations as predicted by the gap between the parallel decoding capacity of the constellations and the Gaussian capacity

Identifying the stars on Johann Bayer's Chart of the South Polar Sky

NASA Astrophysics Data System (ADS)

Ridpath, I.

2014-04-01

The first chart of the stars in the region around the south celestial pole was published in 1603 by Johann Bayer (1572-1625) as part of his monumental star atlas called Uranometria. This south polar chart depicted 12 entirely new constellations that had been created only a few years earlier from stars observed during the first Dutch expedition to the East Indies in 1595-97. Bayer's chart plotted 121 stars in the 12 newly invented constellations. Five more stars formed a southern extension of the existing constellation Eridanus, while another twelve stars were left 'unformed', i.e. unattached to any constellation. Whereas Bayer famously applied Greek or Roman letters to the stars in the 48 Ptolemaic constellations, he left the stars in the newly invented constellations unlabelled. This paper attempts to identify the stars plotted on Bayer's chart. It also discusses the source of Bayer's data and the origin of the 12 new southern constellations.

CubeSat Constellation Cloud Winds(C3Winds) A New Wind Observing System to Study Mesoscale Cloud Dynamics and Processes

NASA Technical Reports Server (NTRS)

Wu, D. L.; Kelly, M.A.; Yee, J.-H.; Boldt, J.; Demajistre, R.; Reynolds, E. L.; Tripoli, G. J.; Oman, L. D.; Prive, N.; Heidinger, A. K.;

Analytical investigation of the dynamics of tethered constellations in Earth orbit (phase 2)

NASA Technical Reports Server (NTRS)

Lorenzini, E.; Arnold, D. A.; Grossi, M. D.; Gullahorn, G. E.

1985-01-01

The deployment maneuver of three axis vertical constellations with elastic tethers is analyzed. The deployment strategy devised previously was improved. Dampers were added to the system. Effective algorithms for damping out the fundamental vibrational modes of the system were implemented. Simulations of a complete deployment and a subsequent station keeping phase of a three mass constellation is shown.

The Cloudsat Mission and the EOS Constellation: A New Dimension of Space-Based Observation of Clouds and Precipitation

NASA Technical Reports Server (NTRS)

Stephens, Graeme L.; Vane, Deborah G.; Boain, Ronald; Mace, Gerald; Sassen, Kenneth; Wang, Zhien; Illingworth, Anthony; OConnor, Ewan; Rossow, William; Durden, Stephen L.;

The Global Positioning System constellation as a space weather monitor. Comparison of electron measurements with Van Allen Probes data

DOE Office of Scientific and Technical Information (OSTI.GOV)

Morley, Steven K.; Sullivan, John P.; Henderson, Michael G.

Energetic electron observations in Earth's radiation belts are typically sparse, and multipoint studies often rely on serendipitous conjunctions. This paper establishes the scientific utility of the Combined X-ray Dosimeter (CXD), currently flown on 19 satellites in the Global Positioning System (GPS) constellation, by cross-calibrating energetic electron measurements against data from the Van Allen Probes. By breaking our cross calibration into two parts—one that removes any spectral assumptions from the CXD flux calculation and one that compares the energy spectra—we first validate the modeled instrument response functions, then the calculated electron fluxes. Unlike previous forward modeling of energetic electron spectra, wemore » use a combination of four distributions that together capture a wide range of observed spectral shapes. Moreover, our two-step approach allowed us to identify, and correct for, small systematic offsets between block IIR and IIF satellites. Using the Magnetic Electron Ion Spectrometer and Relativistic Electron-Proton Telescope on Van Allen Probes as a “gold standard,” here we demonstrate that the CXD instruments are well understood. A robust statistical analysis shows that CXD and Van Allen Probes fluxes are similar and the measured fluxes from CXD are typically within a factor of 2 of Van Allen Probes at energies inline image4 MeV. Our team present data from 17 CXD-equipped GPS satellites covering the 2015 “St. Patrick's Day” geomagnetic storm to illustrate the scientific applications of such a high data density satellite constellation and therefore demonstrate that the GPS constellation is positioned to enable new insights in inner magnetospheric physics and space weather forecasting.« less

The Global Positioning System constellation as a space weather monitor. Comparison of electron measurements with Van Allen Probes data

DOE PAGES

Morley, Steven K.; Sullivan, John P.; Henderson, Michael G.; ...

2016-02-06

Energetic electron observations in Earth's radiation belts are typically sparse, and multipoint studies often rely on serendipitous conjunctions. This paper establishes the scientific utility of the Combined X-ray Dosimeter (CXD), currently flown on 19 satellites in the Global Positioning System (GPS) constellation, by cross-calibrating energetic electron measurements against data from the Van Allen Probes. By breaking our cross calibration into two parts—one that removes any spectral assumptions from the CXD flux calculation and one that compares the energy spectra—we first validate the modeled instrument response functions, then the calculated electron fluxes. Unlike previous forward modeling of energetic electron spectra, wemore » use a combination of four distributions that together capture a wide range of observed spectral shapes. Moreover, our two-step approach allowed us to identify, and correct for, small systematic offsets between block IIR and IIF satellites. Using the Magnetic Electron Ion Spectrometer and Relativistic Electron-Proton Telescope on Van Allen Probes as a “gold standard,” here we demonstrate that the CXD instruments are well understood. A robust statistical analysis shows that CXD and Van Allen Probes fluxes are similar and the measured fluxes from CXD are typically within a factor of 2 of Van Allen Probes at energies inline image4 MeV. Our team present data from 17 CXD-equipped GPS satellites covering the 2015 “St. Patrick's Day” geomagnetic storm to illustrate the scientific applications of such a high data density satellite constellation and therefore demonstrate that the GPS constellation is positioned to enable new insights in inner magnetospheric physics and space weather forecasting.« less

Science Discoveries Enabled by Hosting Optical Imagers on Commercial Satellite Constellations

NASA Astrophysics Data System (ADS)

Erlandson, R. E.; Kelly, M. A.; Hibbitts, C.; Kumar, C.; Dyrud, L. P.

2012-12-01

The advent of commercial space activities that utilize large space-based constellations provide a new and cost effective opportunity to acquire multi-point observations. Previously, a custom designed space-based constellation, while technically feasible, would require a substantial monetary investment. However, commercial industry has now been entertaining the concept of hosting payloads on their space-based constellations resulting in low-cost access to space. Examples, include the low Earth orbit Iridium Next constellation as well as communication satellites in geostationary. In some of these constellations data distribution can be provided in real time, a feature relevant to applications in the areas of space weather and disaster monitoring. From the perspective of new scientific discoveries enabled by low cost access to space, the cost and thus value proposition is dramatically changed. For example, a constellation of sixty-six satellites (Iridium Next), hosting a single band or multi-spectral imager can now provide observations of the aurora with a spatial resolution of a few hundred meters at all local times and in both hemispheres simultaneously. Remote sensing of clouds is another example where it is now possible to acquire global imagery at resolutions between 100-1000m. Finally, land use imagery is another example where one can use either imaging or spectrographic imagers to solve a multitude of problems. In this work, we will discuss measurement architectures and the multi-disciplinary scientific discoveries that are enable by large space based constellations.

Multiple Autonomous Discrete Event Controllers for Constellations

NASA Technical Reports Server (NTRS)

Esposito, Timothy C.

2003-01-01

The Multiple Autonomous Discrete Event Controllers for Constellations (MADECC) project is an effort within the National Aeronautics and Space Administration Goddard Space Flight Center's (NASA/GSFC) Information Systems Division to develop autonomous positioning and attitude control for constellation satellites. It will be accomplished using traditional control theory and advanced coordination algorithms developed by the Johns Hopkins University Applied Physics Laboratory (JHU/APL). This capability will be demonstrated in the discrete event control test-bed located at JHU/APL. This project will be modeled for the Leonardo constellation mission, but is intended to be adaptable to any constellation mission. To develop a common software architecture. the controllers will only model very high-level responses. For instance, after determining that a maneuver must be made. the MADECC system will output B (Delta)V (velocity change) value. Lower level systems must then decide which thrusters to fire and for how long to achieve that (Delta)V.

Collision Avoidance: Coordination of Predicted Conjunctions between NASA Satellites and Satellites of other Countries

NASA Astrophysics Data System (ADS)

Kelly, A.; Watson, W.

2014-09-01

This paper describes one of the challenges facing the flight operations teams of the International Earth Observing constellation satellites at the 705 km orbit, including NASAs satellites. The NASA Earth Science Mission Operations (ESMO) Project has been dealing with predicted conjunctions (close approach) between operational/non-operational space objects and the satellites in the International Earth observing constellations for several years. Constellation satellites include: NASAs Earth Observing System (EOS) Terra, Aqua, and Aura, CloudSat, the joint NASA/CNES CALIPSO mission, Earth Observing 1 (EO-1), the Japan Aerospace and Exploration Agency (JAXA) Global Change Observation Mission-Water 1 (GCOM-W1) mission, the United States Geological Survey (USGS) Landsat 7 and Landsat 8, and until 2013, Argentinas SAC-C mission and the CNES PARASOL mission. The NASA Conjunction Analysis and Risk Assessment (CARA) team provides daily reports to the ESMO Project regarding any high interest close approach events (HIEs) involving the constellation satellites. The daily CARA reports provide risk assessment results that help the operations teams to determine if there is a need to perform a risk mitigation action. If the conjuncting space object is an operational satellite that is capable of maneuvering, the affected satellite team needs to coordinate their action plan with the owner operator of the conjuncting satellite. It is absolutely critical for the two teams to communicate as soon as possible. The goal is to minimize the collision risk; this can happen if both satellite operators do not coordinate their maneuver plans. The constellation teams have established guidelines for coordinating HIEs. This coordination process has worked successfully for several years for satellites that are operated by other organizations in the United States and by NASAs international partners, all with whom NASA has a cooperative agreement. However, the situation is different for HIEs with satellites of foreign operators that do not have an agreement with NASA and the constellation organizations. The current process for coordinating close approach events is neither timely nor satisfactory. Due to the concern that NASAs multi-billion dollar assets at the 705 km orbit can be wiped out by a collision with satellites of foreign operators, the NASA ESMO Project and the CARA team are proposing a more timely coordination and communication process to resolve and safely mitigate these HIEs. This proposed process does not violate any existing communication constraints between the United States and certain foreign operators. This proposal, as described in this paper, will be presented at the conference and comments from other satellite operators will be welcomed and greatly appreciated.

Earth Orbiting Support Systems for commercial low Earth orbit data relay: Assessing architectures through tradespace exploration

NASA Astrophysics Data System (ADS)

Palermo, Gianluca; Golkar, Alessandro; Gaudenzi, Paolo

2015-06-01

As small satellites and Sun Synchronous Earth Observation systems are assuming an increased role in nowadays space activities, including commercial investments, it is of interest to assess how infrastructures could be developed to support the development of such systems and other spacecraft that could benefit from having a data relay service in Low Earth Orbit (LEO), as opposed to traditional Geostationary relays. This paper presents a tradespace exploration study of the architecture of such LEO commercial satellite data relay systems, here defined as Earth Orbiting Support Systems (EOSS). The paper proposes a methodology to formulate architectural decisions for EOSS constellations, and enumerate the corresponding tradespace of feasible architectures. Evaluation metrics are proposed to measure benefits and costs of architectures; lastly, a multicriteria Pareto criterion is used to downselect optimal architectures for subsequent analysis. The methodology is applied to two case studies for a set of 30 and 100 customer-spacecraft respectively, representing potential markets for LEO services in Exploration, Earth Observation, Science, and CubeSats. Pareto analysis shows how increased performance of the constellation is always achieved by an increased node size, as measured by the gain of the communications antenna mounted on EOSS spacecraft. On the other hand, nonlinear trends in optimal orbital altitude, number of satellites per plane, and number of orbital planes, are found in both cases. An upward trend in individual node memory capacity is found, although never exceeding 256 Gbits of onboard memory for both cases that have been considered, assuming the availability of a polar ground station for EOSS data downlink. System architects can use the proposed methodology to identify optimal EOSS constellations for a given service pricing strategy and customer target, thus identifying alternatives for selection by decision makers.

The Earth Science Afternoon Constellation: Preparing for Autonomous but Coordinated Operations

NASA Technical Reports Server (NTRS)

Case, Warren; Kelly, Angelita C.; Work, Kevin; Guit, William

2005-01-01

This paper describes how the challenges of coordinating the autonomous operations of geographically dispersed mission control centers for several small and large satellites are being overcome. The Earth Science Afternoon Constellation, also referred to as the "A-Train", is an international grouping of five NASA satellites (two major NASA EOS missions and three NASA/Earth System Science Pathfinder missions) and one French satellite orbiting in close proximity. This grouping of satellites provides scientists with the opportunity to perform coincident observations using data from two or more instruments on various satellites with measurements taken at approximately the same time. Three of the six missions are currently on-orbit, with the two missions expected to join the constellation later this year and one mission in 2007. The operational challenges are daunting for several reasons. There are several Mission Control Centers (widely separated on two continents), operating autonomously under tight budget constraints. All of the Mission Control Centers have reasons to be concerned about safety while flying in close proximity to other satellites, but most Centers did not have the resources or the desire to address this concern alone - the interfaces are too numerous and anticipated operations too costly. Clearly, an efficient approach was needed. This paper describes the steps taken to make this Earth science constellation a reality. Agreements were forged to allow the Mission Control Centers to maintain their autonomy, while ensuring their satellite's safety. Each member mission in the constellation operates independently in accordance with its own mission requirements, but the member missions have agreed to coordinate their operations, i.e., orbital positions and control to ensure the safety of the entire constellation. A centralized system was developed at NASA Goddard Space Flight Center to collect, analyze, and distribute ephemeris data used by each of the mission teams to determine the positions of the satellites in the constellation. The system issues warnings regarding possible dangerous configurations, eliminating the need for redundant capabilities at each Mission Control Center. On-orbit contingency situations were identified and analyzed; agreements were reached in advance of contingency operations to ensure that coordination between the Mission Control Centers can be handled expeditiously and fairly. In this manner, recovery from anomalous situations can be more quickly realized, thereby increasing the science return and reducing costs. The process used to develop these contingency procedures and the systems used to facilitate the contingency resolution are described as well.

FAST TRACK COMMUNICATION: Affine constellations without mutually unbiased counterparts

NASA Astrophysics Data System (ADS)

Weigert, Stefan; Durt, Thomas

2010-10-01

It has been conjectured that a complete set of mutually unbiased bases in a space of dimension d exists if and only if there is an affine plane of order d. We introduce affine constellations and compare their existence properties with those of mutually unbiased constellations. The observed discrepancies make a deeper relation between the two existence problems unlikely.

The Global Precipitation Measurement (GPM) Mission: Overview and U.S. Status

NASA Technical Reports Server (NTRS)

Hou, Arthur Y.; Azarbarzin, Ardeshir A.; Kakar, Ramesh K.; Neeck, Steven

2011-01-01

The Global Precipitation Measurement (GPM) Mission is an international satellite mission specifically designed to unify and advance precipitation measurements from a constellation of research and operational microwave sensors. The cornerstone of the GPM mission is the deployment of a Core Observatory in a 65 deg non-Sun-synchronous orbit to serve as a physics observatory and a transfer standard for inter-calibration of constellation radiometers. The GPM Core Observatory will carry a Ku/Ka-band Dual-frequency Precipitation Radar (DPR) and a conical-scanning multi-channel (10-183 GHz) GPM Microwave Radiometer (GMI). The first space-borne dual-frequency radar will provide not only measurements of 3-D precipitation structures but also quantitative information on microphysical properties of precipitating particles needed for improving precipitation retrievals from passive microwave sensors. The combined use of DPR and GMI measurements will place greater constraints on radiometer retrievals to improve the accuracy and consistency of precipitation estimates from all constellation radiometers. The GPM constellation is envisioned to comprise five or more conical-scanning microwave radiometers and four or more cross-track microwave sounders on operational satellites. NASA and the Japan Aerospace Exploration Agency (JAXA) plan to launch the GPM Core in July 2013. NASA will provide a second radiometer to be flown on a partner-provided GPM Low-Inclination Observatory (L10) to improve near real-time monitoring of hurricanes and mid-latitude storms. NASA and the Brazilian Space Program (AEB/IPNE) are currently engaged in a one-year study on potential L10 partnership. JAXA will contribute to GPM data from the Global Change Observation Mission-Water (GCOM-W) satellite. Additional partnerships are under development to include microwave radiometers on the French-Indian Megha-Tropiques satellite and U.S. Defense Meteorological Satellite Program (DMSP) satellites, as well as cross-track scanning humidity sounders on operational satellites such as the National Polar-orbiting Operational Environmental Satellite System (NPOESS) Preparatory Project (NPP), POES, the NASA/NOAA Joint Polar Satellite System (JPSS), and EUMETSAT MetOp satellites. Data from Chinese and Russian microwave radiometers may also become available through international collaboration under the auspices of the Committee on Earth Observation Satellites (CEOS) and Group on Earth Observations (GEO). The current generation of global rainfall products combines observations from a network of uncoordinated satellite missions using a variety of merging techniques. Relative to current data products, GPM's "nextgeneration" precipitation products will be characterized by: (1) more accurate instantaneous precipitation estimate (especially for light rain and cold-season solid precipitation), (2) more frequent sampling by an expanded constellation of microwave radiometers including operational humidity sounders over land, (3) intercalibrated microwave brightness temperatures from constellation radiometers within a unified framework, and (4) physical-based precipitation retrievals from constellation radiometers using a common a priori hydrometeor database constrained by combined radar/radiometer measurements provided by the GPM Core Observatory. An overview of the GPM mission concept, the U.S. GPM program status and updates on international science collaborations on GPM will be presented.

Precipitation Estimation Using Combined Radar/Radiometer Measurements Within the GPM Framework

NASA Technical Reports Server (NTRS)

Hou, Arthur

2012-01-01

The Global Precipitation Measurement (GPM) Mission is an international satellite mission specifically designed to unify and advance precipitation measurements from a constellation of research and operational microwave sensors. The GPM mission centers upon the deployment of a Core Observatory in a 65o non-Sun-synchronous orbit to serve as a physics observatory and a transfer standard for intersatellite calibration of constellation radiometers. The GPM Core Observatory will carry a Ku/Ka-band Dual-frequency Precipitation Radar (DPR) and a conical-scanning multi-channel (10-183 GHz) GPM Microwave Radiometer (GMI). The DPR will be the first dual-frequency radar in space to provide not only measurements of 3-D precipitation structures but also quantitative information on microphysical properties of precipitating particles needed for improving precipitation retrievals from microwave sensors. The DPR and GMI measurements will together provide a database that relates vertical hydrometeor profiles to multi-frequency microwave radiances over a variety of environmental conditions across the globe. This combined database will be used as a common transfer standard for improving the accuracy and consistency of precipitation retrievals from all constellation radiometers. For global coverage, GPM relies on existing satellite programs and new mission opportunities from a consortium of partners through bilateral agreements with either NASA or JAXA. Each constellation member may have its unique scientific or operational objectives but contributes microwave observations to GPM for the generation and dissemination of unified global precipitation data products. In addition to the DPR and GMI on the Core Observatory, the baseline GPM constellation consists of the following sensors: (1) Special Sensor Microwave Imager/Sounder (SSMIS) instruments on the U.S. Defense Meteorological Satellite Program (DMSP) satellites, (2) the Advanced Microwave Scanning Radiometer-2 (AMSR-2) on the GCOM-W1 satellite of JAXA, (3) the Multi-Frequency Microwave Scanning Radiometer (MADRAS) and the multi-channel microwave humidity sounder (SAPHIR) on the French-Indian Megha- Tropiques satellite, (4) the Microwave Humidity Sounder (MHS) on the National Oceanic and Atmospheric Administration (NOAA)-19, (5) MHS instruments on MetOp satellites launched by the European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT), (6) the Advanced Technology Microwave Sounder (ATMS) on the National Polar-orbiting Operational Environmental Satellite System (NPOESS) Preparatory Project (NPP), and (7) ATMS instruments on the NOAA-NASA Joint Polar Satellite System (JPSS) satellites. Data from Chinese and Russian microwave radiometers may also become available through international collaboration under the auspices of the Committee on Earth Observation Satellites (CEOS) and Group on Earth Observations (GEO). The current generation of global rainfall products combines observations from a network of uncoordinated satellite missions using a variety of merging techniques. GPM will provide next-generation precipitation products characterized by: (1) more accurate instantaneous precipitation estimate (especially for light rain and cold-season solid precipitation), (2) intercalibrated microwave brightness temperatures from constellation radiometers within a consistent framework, and (3) unified precipitation retrievals from constellation radiometers using a common a priori hydrometeor database constrained by combined radar/radiometer measurements provided by the GPM Core Observatory.

Point pattern match-based change detection in a constellation of previously detected objects

DOEpatents

Paglieroni, David W.

2016-06-07

A method and system is provided that applies attribute- and topology-based change detection to objects that were detected on previous scans of a medium. The attributes capture properties or characteristics of the previously detected objects, such as location, time of detection, detection strength, size, elongation, orientation, etc. The locations define a three-dimensional network topology forming a constellation of previously detected objects. The change detection system stores attributes of the previously detected objects in a constellation database. The change detection system detects changes by comparing the attributes and topological consistency of newly detected objects encountered during a new scan of the medium to previously detected objects in the constellation database. The change detection system may receive the attributes of the newly detected objects as the objects are detected by an object detection system in real time.

The Solar system.Stars and constellations

NASA Astrophysics Data System (ADS)

Horia Minda, Octavian

2017-04-01

It is important for students to understand what is in our Solar System. The Students need to know that there are other things besides the Earth, Sun and Moon in the solar sky. The students will learn about the other eight planets and a few other celestial objects like stars and constellations. Constellations are useful because they can help people to recognize stars in the sky. By looking for patterns, the stars and locations can be much easier to spot. The constellations had uses in ancient times. They were used to help keep track of the calendar. This was very important so that people knew when to plant and harvest crops. Another important use for constellations was navigation. By finding Ursa Minor it is fairly easy to spot the North Star (Polaris). Using the height of the North Star in the sky, navigators could figure out their latitude helping ships to travel across the oceans. Objective: 1. The students will be introduced to the origin of the stars they see at night. 2. They will learn that there are groups of stars called constellations. The students will individually create their own constellations. They will be given the chance to tell the class a small story explaining their constellation. Evaluation of Children: The children will be evaluated through the creation of their constellations and ability to work in groups on the computers.

Space Weather Observations by GNSS Radio Occultation: From FORMOSAT-3/COSMIC to FORMOSAT-7/COSMIC-2

PubMed Central

Yue, Xinan; Schreiner, William S; Pedatella, Nicholas; Anthes, Richard A; Mannucci, Anthony J; Straus, Paul R; Liu, Jann-Yenq

2014-01-01

The joint Taiwan-United States FORMOSAT-3/COSMIC (Constellation Observing System for Meteorology, Ionosphere, and Climate) mission, hereafter called COSMIC, is the first satellite constellation dedicated to remotely sense Earth's atmosphere and ionosphere using a technique called Global Positioning System (GPS) radio occultation (RO). The occultations yield abundant information about neutral atmospheric temperature and moisture as well as space weather estimates of slant total electron content, electron density profiles, and an amplitude scintillation index, S4. With the success of COSMIC, the United States and Taiwan are moving forward with a follow-on RO mission named FORMOSAT-7/COSMIC-2 (COSMIC-2), which will ultimately place 12 satellites in orbit with two launches in 2016 and 2019. COSMIC-2 satellites will carry an advanced Global Navigation Satellite System (GNSS) RO receiver that will track both GPS and Russian Global Navigation Satellite System signals, with capability for eventually tracking other GNSS signals from the Chinese BeiDou and European Galileo system, as well as secondary space weather payloads to measure low-latitude plasma drifts and scintillation at multiple frequencies. COSMIC-2 will provide 4–6 times (10–15X in the low latitudes) the number of atmospheric and ionospheric observations that were tracked with COSMIC and will also improve the quality of the observations. In this article we focus on COSMIC/COSMIC-2 measurements of key ionospheric parameters. PMID:26213514

Space Weather Observations by GNSS Radio Occultation: From FORMOSAT-3/COSMIC to FORMOSAT-7/COSMIC-2.

PubMed

Yue, Xinan; Schreiner, William S; Pedatella, Nicholas; Anthes, Richard A; Mannucci, Anthony J; Straus, Paul R; Liu, Jann-Yenq

2014-11-01

The joint Taiwan-United States FORMOSAT-3/COSMIC (Constellation Observing System for Meteorology, Ionosphere, and Climate) mission, hereafter called COSMIC, is the first satellite constellation dedicated to remotely sense Earth's atmosphere and ionosphere using a technique called Global Positioning System (GPS) radio occultation (RO). The occultations yield abundant information about neutral atmospheric temperature and moisture as well as space weather estimates of slant total electron content, electron density profiles, and an amplitude scintillation index, S4. With the success of COSMIC, the United States and Taiwan are moving forward with a follow-on RO mission named FORMOSAT-7/COSMIC-2 (COSMIC-2), which will ultimately place 12 satellites in orbit with two launches in 2016 and 2019. COSMIC-2 satellites will carry an advanced Global Navigation Satellite System (GNSS) RO receiver that will track both GPS and Russian Global Navigation Satellite System signals, with capability for eventually tracking other GNSS signals from the Chinese BeiDou and European Galileo system, as well as secondary space weather payloads to measure low-latitude plasma drifts and scintillation at multiple frequencies. COSMIC-2 will provide 4-6 times (10-15X in the low latitudes) the number of atmospheric and ionospheric observations that were tracked with COSMIC and will also improve the quality of the observations. In this article we focus on COSMIC/COSMIC-2 measurements of key ionospheric parameters.

Orbit determination of the Next-Generation Beidou satellites with Intersatellite link measurements and a priori orbit constraints

NASA Astrophysics Data System (ADS)

Ren, Xia; Yang, Yuanxi; Zhu, Jun; Xu, Tianhe

2017-11-01

Intersatellite Link (ISL) technology helps to realize the auto update of broadcast ephemeris and clock error parameters for Global Navigation Satellite System (GNSS). ISL constitutes an important approach with which to both improve the observation geometry and extend the tracking coverage of China's Beidou Navigation Satellite System (BDS). However, ISL-only orbit determination might lead to the constellation drift, rotation, and even lead to the divergence in orbit determination. Fortunately, predicted orbits with good precision can be used as a priori information with which to constrain the estimated satellite orbit parameters. Therefore, the precision of satellite autonomous orbit determination can be improved by consideration of a priori orbit information, and vice versa. However, the errors of rotation and translation in a priori orbit will remain in the ultimate result. This paper proposes a constrained precise orbit determination (POD) method for a sub-constellation of the new Beidou satellite constellation with only a few ISLs. The observation model of dual one-way measurements eliminating satellite clock errors is presented, and the orbit determination precision is analyzed with different data processing backgrounds. The conclusions are as follows. (1) With ISLs, the estimated parameters are strongly correlated, especially the positions and velocities of satellites. (2) The performance of determined BDS orbits will be improved by the constraints with more precise priori orbits. The POD precision is better than 45 m with a priori orbit constrain of 100 m precision (e.g., predicted orbits by telemetry tracking and control system), and is better than 6 m with precise priori orbit constraints of 10 m precision (e.g., predicted orbits by international GNSS monitoring & Assessment System (iGMAS)). (3) The POD precision is improved by additional ISLs. Constrained by a priori iGMAS orbits, the POD precision with two, three, and four ISLs is better than 6, 3, and 2 m, respectively. (4) The in-plane link and out-of-plane link have different contributions to observation configuration and system observability. The POD with weak observation configuration (e.g., one in-plane link and one out-of-plane link) should be tightly constrained with a priori orbits.

CubeSat constellations for disaster management in remote areas

NASA Astrophysics Data System (ADS)

Santilli, Giancarlo; Vendittozzi, Cristian; Cappelletti, Chantal; Battistini, Simone; Gessini, Paolo

2018-04-01

In recent years, CubeSats have considerably extended their range of possible applications, from a low cost means to train students and young researchers in space related activities up to possible complementary solutions to larger missions. Increasingly popular, whereas CubeSats are still not a solution for all types of missions, they offer the possibility of performing ambitious scientific experiments. Especially worth considering is the possibility of performing Distributed Space Missions, in which CubeSat systems can be used to increase observation sampling rates and resolutions, as well as to perform tasks that a single satellite is unable to handle. The cost of access to space for traditional Earth Observation (EO) missions is still quite high. Efficient architecture design would allow reducing mission costs by employing CubeSat systems, while maintaining a level of performance that, for some applications, could be close to that provided by larger platforms, and decreasing the time needed to design and deploy a fully functional constellation. For these reasons many countries, including developing nations, agencies and organizations are looking to CubeSat platforms to access space cheaply with, potentially, tens of remote sensing satellites. During disaster management, real-time, fast and continuous information broadcast is a fundamental requirement. In this sense, a constellation of small satellites can considerably decrease the revisit time (defined as the time elapsed between two consecutive observations of the same point on Earth by a satellite) over remote areas, by increasing the number of spacecraft properly distributed in orbit. This allows collecting as much data as possible for the use by Disaster Management Centers. This paper describes the characteristics of a constellation of CubeSats built to enable access over the most remote regions of Brazil, supporting an integrated system for mitigating environmental disasters in an attempt to prevent the catastrophic effects of natural events such as heavy rains that cause flooding. In particular, the paper defines the number of CubeSats and the orbital planes required to minimize the revisit time, depending on the application that is the mission objective. Each CubeSat is equipped with the suitable payloads and possesses the autonomy and pointing capabilities needed to meet the mission requirements. Thanks to the orbital features of the constellation, this service could be exploited by other tropical countries. Coverage of other areas of the Earth might be provided by adjusting the number and in-orbit distribution of the spacecraft.

The BDS iGMAS RIOS station at Observatório Nacional, Rio de Janeiro

NASA Astrophysics Data System (ADS)

Humberto Andrei, Alexandre; Song, Shuli; Junqueira, Selma; Beauvalet, Laurene

2016-07-01

GNSS navigation satellites are currently being developed by all major players in the science and technology scene, to compete with the GPS system. Because their applications span many different areas, from traffic and cargo control, to geodesy and seismic monitoring, it is required to assess the coherence between the different constellations. BDS is the GNSS system currently developed in China. Its first generation of satellites consisted of 3 geostationnary satellites allowing geolocalisation in China only. In addition to these satellites, other satellites have been launched in geostationnary and geosynchronous orbits, as well as satellites orbiting with a classical GNSS semi-major axis. With these additions, the BDS system possesses 19 operating satellites, and though the system is mostly efficient for geolocalisation in Asia, the satellites are also visible in other parts of the globe. In parallel to the development of the BDS constellation, China has launched the iGMAS (International GNSS Monitoring and Assessment Service) project to develop a global tracking network of multi-GNSS geodetic receivers. One of the goals of this project is to evaluate the efficiency of the BDS constellation as well as the efficiency of the receivers developed by the Chinese laboratories. As part of the Brazilian program COSBAN leaded by the Foreign Affairs Ministry to foster up the science and technology partnership with China, materialized by the collaboration between the Shanghai Astronomical Observatory/CAS and the Observatório Nacional/MCTI, in Rio de Janeiro. Through it the RIOS-iGMAS station was installed at Observatório Nacional, where the RJEP GNSS station already operates as part of the Brazilian reference system. Thus at the Observatório Nacional can be observed satellites from any constellation with both systems of reception, leading to a direct, efficient way to compare the results obtained for each network. In this communication we focus on the determination of the position of the satellites by analyzing the pseudo-ranges obtained by C1W code for GPS, and C7I code for BDS. Using the Allan variation a crucial result is obtained. It is shown that the BDS system can perform at the level of the GPS system, provided equal satellite coverage. On the other hand at the Observatório Nacional it is detected a near constant bias of about 35m between the ranges simultaneously derived from the RIOS (iGMAS) and RJEP (GNSS) stations, no matter the observed satellite, or constellation. Both results are presented and discussed. We also present the current status of the installation of a second BDS iGMAS station, in a northern, equatorial location in Brazil. The operational and scientific perspectives are disclosed.

Secure optical generalized filter bank multi-carrier system based on cubic constellation masked method.

PubMed

Zhang, Lijia; Liu, Bo; Xin, Xiangjun

2015-06-15

A secure optical generalized filter bank multi-carrier (GFBMC) system with carrier-less amplitude-phase (CAP) modulation is proposed in this Letter. The security is realized through cubic constellation-masked method. Large key space and more flexibility masking can be obtained by cubic constellation masking aligning with the filter bank. An experiment of 18 Gb/s encrypted GFBMC/CAP system with 25-km single-mode fiber transmission is performed to demonstrate the feasibility of the proposed method.

Flower elliptical constellation of millimeter-wave radiometers for precipitating cloud monitoring at geostationary scale

NASA Astrophysics Data System (ADS)

Marzano, F. S.; Cimini, D.; Montopoli, M.; Rossi, T.; Mortari, D.; di Michele, S.; Bauer, P.

2009-04-01

Millimeter-wave observation of the atmospheric parameters is becoming an appealing goal within satellite radiometry applications. The major technological advantage of millimeter-wave (MMW) radiometers is the reduced size of the overall system, for given performances, with respect to microwave sensor. On the other hand, millimeter-wave sounding can exploit window frequencies and various gaseous absorption bands at 50/60 GHz, 118 GHz and 183 GHz. These bands can be used to estimate tropospheric temperature profiles, integrated water vapor and cloud liquid content and, using a differentia spectral mode, light rainfall and snowfall. Millimeter-wave radiometers, for given observation conditions, can also exhibit relatively small field-of-views (FOVs), of the order of some kilometers for low-Earth-orbit (LEO) satellites. However, the temporal resolution of LEO millimeter-wave system observations remains a major drawback with respect to the geostationary-Earth-orbit (GEO) satellites. An overpass every about 12 hours for a single LEO platform (conditioned to a sufficiently large swath of the scanning MMW radiometer) is usually too much when compared with the typical temporal scale variation of atmospheric fields. This feature cannot be improved by resorting to GEO platforms due to their high orbit altitude and consequent degradation of the MMW-sensor FOVs. A way to tackle this impasse is to draw our attention at the regional scale and to focus non-circular orbits over the area of interest, exploiting the concept of micro-satellite flower constellations. The Flower Constellations (FCs) is a general class of elliptical orbits which can be optimized, through genetic algorithms, in order to maximize the revisiting time and the orbital height, ensuring also a repeating ground-track. The constellation concept nicely matches the choice of mini-satellites as a baseline choice, due to their small size, weight (less than 500 kilograms) and relatively low cost (essential when deploying several identical speceborne platforms). Moreover, the micro-satellite solution clearly addresses the choice of small passive sensors with small size, low weight and power consumption, features which cannot be usually satisfied by active sensors. In this respect, MMW technology is the most compatible with the specifications and constraints of micro-satellites. In this work, we will discuss the numerical results of a feasibility study aimed at designing a Flower elliptical constellation of 3 micro-satellite millimeter-wave radiometers for pseudo-geostationary atmospheric observations over the Mediterranean region. The Flower constellation will be optimized in such a way to simulate a pseudo-geostationary observation of the Mediterranean area with an observation repetition time less than 2 hours. The mission requirements request the retrieval of thermodinamical and hydrological properties of the troposphere, specifically temperature profiles, integrated water vapor and cloud liquid content, rainfall and snowfall. Several configurations of the MMW radiometer multi-band channels will be discussed, pointing out the trade-off between performances and complexity. Integrated estimation algorithms, based on a Bayesian approache, will be illustrated to retrieve the requested atmospheric parameters, discussing its sensitivity to sensor radiometric precision and accuracy within each frequency-set configuration. After this numerical study, a review of the mission requirements and specifications will be also proposed.

An Approach to Speed up Single-Frequency PPP Convergence with Quad-Constellation GNSS and GIM

PubMed Central

Cai, Changsheng; Gong, Yangzhao; Gao, Yang; Kuang, Cuilin

2017-01-01

The single-frequency precise point positioning (PPP) technique has attracted increasing attention due to its high accuracy and low cost. However, a very long convergence time, normally a few hours, is required in order to achieve a positioning accuracy level of a few centimeters. In this study, an approach is proposed to accelerate the single-frequency PPP convergence by combining quad-constellation global navigation satellite system (GNSS) and global ionospheric map (GIM) data. In this proposed approach, the GPS, GLONASS, BeiDou, and Galileo observations are directly used in an uncombined observation model and as a result the ionospheric and hardware delay (IHD) can be estimated together as a single unknown parameter. The IHD values acquired from the GIM product and the multi-GNSS differential code bias (DCB) product are then utilized as pseudo-observables of the IHD parameter in the observation model. A time varying weight scheme has also been proposed for the pseudo-observables to gradually decrease its contribution to the position solutions during the convergence period. To evaluate the proposed approach, datasets from twelve Multi-GNSS Experiment (MGEX) stations on seven consecutive days are processed and analyzed. The numerical results indicate that the single-frequency PPP with quad-constellation GNSS and GIM data are able to reduce the convergence time by 56%, 47%, 41% in the east, north, and up directions compared to the GPS-only single-frequency PPP. PMID:28587305

The interhemispheric and F region dynamo currents revisited with the Swarm constellation

NASA Astrophysics Data System (ADS)

Lühr, Hermann; Kervalishvili, Guram; Michaelis, Ingo; Rauberg, Jan; Ritter, Patricia; Park, Jaeheung; Merayo, Jose M. G.; Brauer, Peter

2015-05-01

Based on magnetic field data sampled by the Swarm satellite constellation it is possible for the first time to determine uniquely F region currents at low latitudes. Initial results are presented from the first 200 days of formation flight (17 April to 5 November 2014). Detailed results have been obtained for interhemispheric field-aligned currents connecting the solar quiet day magnetic variation (Sq) current systems in the two hemispheres. We obtain prominent currents from the Southern (winter) Hemisphere to the Northern around noon. Weaker currents in opposite direction are observed during morning and evening hours. Furthermore, we could confirm the existence of vertical currents above the dip equator, downward around noon and upward around sunset. For both current systems we present and discuss longitudinal variations.

Investigation of some selected strategies for multi-GNSS instantaneous RTK positioning

NASA Astrophysics Data System (ADS)

Paziewski, Jacek; Wielgosz, Pawel

2017-01-01

It is clear that we can benefit from multi-constellation GNSS in precise relative positioning. On the other hand, it is still an open problem how to combine multi-GNSS signals in a single functional model. This study presents methodology and quality assessment of selected methods allowing for multi-GNSS observations combining in relative kinematic positioning using baselines up to tens of kilometers. In specific, this paper characterizes loose and tight integration strategies applied to the ionosphere and troposphere weighted model. Performance assessment of the established strategies was based on the analyses of the integer ambiguity resolution and rover coordinates' repeatability obtained in the medium range instantaneous RTK positioning with the use of full constellation dual frequency GPS and Galileo signals. Since full constellation of Galileo satellites is not yet available, the observational data were obtained from a hardware GNSS signal simulator using regular geodetic GNSS receivers. The results indicate on similar and high performance of the loose, and tight integration with calibrated receiver ISBs strategies. These approaches have undeniable advantage over single system positioning in terms of reliability of the integer ambiguity resolution as well as rover coordinate repeatability.

The First Results About Earthquake Study with FORMOSAT-3/COSMIC

NASA Astrophysics Data System (ADS)

Liu, J. Y.; Oyama, K.; Jhuang, H. K.; Istep, M.; Hsiao, C. C.; Wang, Y. H.

2007-12-01

To improve the global weather prediction and space weather monitoring, six microsatellites termed the Formosa Satellite 3 - Constellation Observing System for Meteorology, Ionosphere, and Climate (FORMOSAT-3/COSMIC) were launched into a circular low-Earth orbit (LEO) from Vandenberg Air Force Base, California, at 0140 UTC on 15 April 2006. Each microsatellite of the joint Taiwan-US satellite constellation mission has a GPS occultation experiment (GOX) payload to operate the atmospheric and ionospheric radio occultation, a tiny ionospheric photometer (TIP) to observe the nighttime ionospheric airglow OI 135.6 nm emission, and a tri-band beacon (TBB) to tomographically estimate fine structures of ionospheric electron density on the satellite-to-receiver plane. While the GOX daily observes about 2500 vertical electron density profiles up to the satellite altitude, the TIP provides accurate horizontal gradients of nighttime electron density. In this study, anomalies in the ionospheric electron density structure and dynamics concurrently observed by FORMOSAT-3/COSMIC and co-located ground- based GPS receivers before recent large earthquakes are presented and discussed.

Human Systems Integration in Practice: Constellation Lessons Learned

NASA Technical Reports Server (NTRS)

Zumbado, Jennifer Rochlis

2012-01-01

NASA's Constellation program provided a unique testbed for Human Systems Integration (HSI) as a fundamental element of the Systems Engineering process. Constellation was the first major program to have HSI mandated by NASA's Human Rating document. Proper HSI is critical to the success of any project that relies on humans to function as operators, maintainers, or controllers of a system. HSI improves mission, system and human performance, significantly reduces lifecycle costs, lowers risk and minimizes re-design. Successful HSI begins with sufficient project schedule dedicated to the generation of human systems requirements, but is by no means solely a requirements management process. A top-down systems engineering process that recognizes throughout the organization, human factors as a technical discipline equal to traditional engineering disciplines with authority for the overall system. This partners with a bottoms-up mechanism for human-centered design and technical issue resolution. The Constellation Human Systems Integration Group (HSIG) was a part of the Systems Engineering and Integration (SE&I) organization within the program office, and existed alongside similar groups such as Flight Performance, Environments & Constraints, and Integrated Loads, Structures and Mechanisms. While the HSIG successfully managed, via influence leadership, a down-and-in Community of Practice to facilitate technical integration and issue resolution, it lacked parallel top-down authority to drive integrated design. This presentation will discuss how HSI was applied to Constellation, the lessons learned and best practices it revealed, and recommendations to future NASA program and project managers. This presentation will discuss how Human Systems Integration (HSI) was applied to NASA's Constellation program, the lessons learned and best practices it revealed, and recommendations to future NASA program and project managers on how to accomplish this critical function.

Optimizing the Attitude Control of Small Satellite Constellations for Rapid Response Imaging

NASA Astrophysics Data System (ADS)

Nag, S.; Li, A.

2016-12-01

Distributed Space Missions (DSMs) such as formation flight and constellations, are being recognized as important solutions to increase measurement samples over space and time. Given the increasingly accurate attitude control systems emerging in the commercial market, small spacecraft now have the ability to slew and point within few minutes of notice. In spite of hardware development in CubeSats at the payload (e.g. NASA InVEST) and subsystems (e.g. Blue Canyon Technologies), software development for tradespace analysis in constellation design (e.g. Goddard's TAT-C), planning and scheduling development in single spacecraft (e.g. GEO-CAPE) and aerial flight path optimizations for UAVs (e.g. NASA Sensor Web), there is a gap in open-source, open-access software tools for planning and scheduling distributed satellite operations in terms of pointing and observing targets. This paper will demonstrate results from a tool being developed for scheduling pointing operations of narrow field-of-view (FOV) sensors over mission lifetime to maximize metrics such as global coverage and revisit statistics. Past research has shown the need for at least fourteen satellites to cover the Earth globally everyday using a LandSat-like sensor. Increasing the FOV three times reduces the need to four satellites, however adds image distortion and BRDF complexities to the observed reflectance. If narrow FOV sensors on a small satellite constellation were commanded using robust algorithms to slew their sensor dynamically, they would be able to coordinately cover the global landmass much faster without compensating for spatial resolution or BRDF effects. Our algorithm to optimize constellation satellite pointing is based on a dynamic programming approach under the constraints of orbital mechanics and existing attitude control systems for small satellites. As a case study for our algorithm, we minimize the time required to cover the 17000 Landsat images with maximum signal to noise ratio fall-off and minimum image distortion among the satellites, using Landsat's specifications. Attitude-specific constraints such as power consumption, response time, and stability were factored into the optimality computations. The algorithm can integrate cloud cover predictions, specific ground and air assets and angular constraints.

A Constellation of CubeSat InSAR Sensors for Rapid-Revisit Surface Deformation Studies

NASA Astrophysics Data System (ADS)

Wye, L.; Lee, S.; Yun, S. H.; Zebker, H. A.; Stock, J. D.; Wicks, C. W., Jr.; Doe, R.

2016-12-01

The 2007 NRC Decadal Survey for Earth Sciences highlights three major Earth surface deformation themes: 1) solid-earth hazards and dynamics; 2) human health and security; and 3) land-use change, ecosystem dynamics and biodiversity. Space-based interferometric synthetic aperture radar (InSAR) is a key change detection tool for addressing these themes. Here, we describe the mission and radar payload design for a constellation of S-band InSAR sensors specifically designed to provide the global, high temporal resolution, sub-cm level deformation accuracy needed to address some of the major Earth system goals. InSAR observations with high temporal resolution are needed to properly monitor certain nonlinearly time-varying features (e.g., unstable volcanoes, active fault lines, and heavily-used groundwater or hydrocarbon reservoirs). Good temporal coverage is also needed to reduce atmospheric artifacts by allowing multiple acquisitions to be averaged together, since each individual SAR measurement is corrupted by up to several cm of atmospheric noise. A single InSAR platform is limited in how often it can observe a given scene without sacrificing global spatial coverage. Multiple InSAR platforms provide the spatial-temporal flexibility required to maximize the science return. However, building and launching multiple InSAR platforms is cost-prohibitive for traditional satellites. SRI International (SRI) and our collaborators are working to exploit developments in nanosatellite technology, in particular the emergence of the CubeSat standard, to provide high-cadence InSAR capabilities in an affordable package. The CubeSat Imaging Radar for Earth Science (CIRES) subsystem, a prototype SAR elec­tronics package developed by SRI with support from a 2014 NASA ESTO ACT award, is specifically scaled to be a drop-in radar solution for resource-limited delivery systems like CubeSats and small airborne vehicles. Here, we present our mission concept and flow-down requirements for a constellation of 6U InSAR sensors that individually approach the performance capabilities of existing instruments, but collectively surpass the temporal coverage capabilities of single-platform sensors. We discuss the key applications addressed by this constellation and the capabilities that the constellation enables.

Scheduling algorithms for rapid imaging using agile Cubesat constellations

NASA Astrophysics Data System (ADS)

Nag, Sreeja; Li, Alan S.; Merrick, James H.

2018-02-01

Distributed Space Missions such as formation flight and constellations, are being recognized as important Earth Observation solutions to increase measurement samples over space and time. Cubesats are increasing in size (27U, ∼40 kg in development) with increasing capabilities to host imager payloads. Given the precise attitude control systems emerging in the commercial market, Cubesats now have the ability to slew and capture images within short notice. We propose a modular framework that combines orbital mechanics, attitude control and scheduling optimization to plan the time-varying, full-body orientation of agile Cubesats in a constellation such that they maximize the number of observed images and observation time, within the constraints of Cubesat hardware specifications. The attitude control strategy combines bang-bang and PD control, with constraints such as power consumption, response time, and stability factored into the optimality computations and a possible extension to PID control to account for disturbances. Schedule optimization is performed using dynamic programming with two levels of heuristics, verified and improved upon using mixed integer linear programming. The automated scheduler is expected to run on ground station resources and the resultant schedules uplinked to the satellites for execution, however it can be adapted for onboard scheduling, contingent on Cubesat hardware and software upgrades. The framework is generalizable over small steerable spacecraft, sensor specifications, imaging objectives and regions of interest, and is demonstrated using multiple 20 kg satellites in Low Earth Orbit for two case studies - rapid imaging of Landsat's land and coastal images and extended imaging of global, warm water coral reefs. The proposed algorithm captures up to 161% more Landsat images than nadir-pointing sensors with the same field of view, on a 2-satellite constellation over a 12-h simulation. Integer programming was able to verify that optimality of the dynamic programming solution for single satellites was within 10%, and find up to 5% more optimal solutions. The optimality gap for constellations was found to be 22% at worst, but the dynamic programming schedules were found at nearly four orders of magnitude better computational speed than integer programming. The algorithm can include cloud cover predictions, ground downlink windows or any other spatial, temporal or angular constraints into the orbital module and be integrated into planning tools for agile constellations.

Constellation Program Press Conference

NASA Image and Video Library

2006-06-04

Scott Horowitz, NASA Associate Administrator for Exploration Systems, left, looks on as Jeff Hanley, Constellation Program Manager, speaks during a press conference outlining specific center responsibilities associated with the Constellation Program for robotic and human Moon and Mars exploration, Monday, June 5, 2006, at NASA Headquarters in Washington. Photo Credit (NASA/Bill Ingalls)

Constellation Program Press Conference

NASA Image and Video Library

2006-06-04

Scott Horowitz, NASA Associate Administrator for Exploration Systems, center, speaks as Jeff Hanley, Constellation Program Manager, right, looks on during a press conference outlining specific center responsibilities associated with the Constellation Program for robotic and human Moon and Mars exploration, Monday, June 5, 2006, at NASA Headquarters in Washington. Photo Credit (NASA/Bill Ingalls)

Constellation Program Press Conference

NASA Image and Video Library

2006-06-04

Scott Horowitz, NASA Associate Administrator for Exploration Systems, left, and Jeff Hanley, Constellation Program Manager, are seen during a press conference outlining specific center responsibilities associated with the Constellation Program for robotic and human Moon and Mars exploration, Monday, June 5, 2006, at NASA Headquarters in Washington. Photo Credit (NASA/Bill Ingalls)

The brazilian indigenous planetary-observatory

NASA Astrophysics Data System (ADS)

Afonso, G. B.

2003-08-01

We have performed observations of the sky alongside with the Indians of all Brazilian regions that made it possible localize many indigenous constellations. Some of these constellations are the same as the other South American Indians and Australian aborigines constellations. The scientific community does not have much of this information, which may be lost in one or two generations. In this work, we present a planetary-observatory that we have made in the Park of Science Newton Freire-Maia of Paraná State, in order to popularize the astronomical knowledge of the Brazilian Indians. The planetary consists, essentially, of a sphere of six meters in diameter and a projection cylinder of indigenous constellations. In this planetary we can identify a lot of constellations that we have gotten from the Brazilian Indians; for instance, the four seasonal constellations: the Tapir (spring), the Old Man (summer), the Deer (autumn) and the Rhea (winter). A two-meter height wooden staff that is posted vertically on the horizontal ground similar to a Gnomon and stones aligned with the cardinal points and the soltices directions constitutes the observatory. A stone circle of ten meters in diameter surrounds the staff and the aligned stones. During the day we observe the Sun apparent motions and at night the indigenous constellations. Due to the great community interest in our work, we are designing an itinerant indigenous planetary-observatory to be used in other cities mainly by indigenous and primary schools teachers.

Precise orbit determination of BeiDou constellation based on BETS and MGEX network.

PubMed

Lou, Yidong; Liu, Yang; Shi, Chuang; Yao, Xiuguang; Zheng, Fu

2014-04-15

Chinese BeiDou Navigation Satellite System is officially operational as a regional constellation with five Geostationary Earth Orbit (GEO) satellites, five Inclined Geosynchronous Satellite Orbit (IGSO) satellites and four Medium Earth Orbit (MEO) satellites. Observations from the BeiDou Experimental Tracking Stations (BETS) and the IGS Multi-GNSS Experiment (MGEX) network from 1 January to 31 March 2013 are processed for orbit determination of the BeiDou constellation. Various arc lengths and solar radiation pressure parameters are investigated. The reduced set of ECOM five-parameter model produces better performance than the full set of ECOM nine-parameter model for BeiDou IGSO and MEO. The orbit overlap for the middle days of 3-day arc solutions is better than 20 cm and 14 cm for IGSO and MEO in RMS, respectively. Satellite laser ranging residuals are better than 10 cm for both IGSO and MEO. For BeiDou GEO, the orbit overlap of several meters and satellite laser ranging residuals of several decimetres can be achieved.

Observational Astrology.

ERIC Educational Resources Information Center

Mayer, Ben

1987-01-01

Discusses the use of astrological signs as a vehicle for getting students interested in astronomy. Describes the construction and use of simple stellaphane starframes that can be used to locate astrological constellations. Provides instructions for photographing constellations with a 35 millimeter camera. (TW)

Constellation Ground Systems Launch Availability Analysis: Enhancing Highly Reliable Launch Systems Design

NASA Technical Reports Server (NTRS)

Gernand, Jeffrey L.; Gillespie, Amanda M.; Monaghan, Mark W.; Cummings, Nicholas H.

2010-01-01

Success of the Constellation Program's lunar architecture requires successfully launching two vehicles, Ares I/Orion and Ares V/Altair, within a very limited time period. The reliability and maintainability of flight vehicles and ground systems must deliver a high probability of successfully launching the second vehicle in order to avoid wasting the on-orbit asset launched by the first vehicle. The Ground Operations Project determined which ground subsystems had the potential to affect the probability of the second launch and allocated quantitative availability requirements to these subsystems. The Ground Operations Project also developed a methodology to estimate subsystem reliability, availability, and maintainability to ensure that ground subsystems complied with allocated launch availability and maintainability requirements. The verification analysis developed quantitative estimates of subsystem availability based on design documentation, testing results, and other information. Where appropriate, actual performance history was used to calculate failure rates for legacy subsystems or comparative components that will support Constellation. The results of the verification analysis will be used to assess compliance with requirements and to highlight design or performance shortcomings for further decision making. This case study will discuss the subsystem requirements allocation process, describe the ground systems methodology for completing quantitative reliability, availability, and maintainability analysis, and present findings and observation based on analysis leading to the Ground Operations Project Preliminary Design Review milestone.

Constellation Program Update

NASA Image and Video Library

2006-06-05

Jeff Hanley, Constellation Program Manager, right, and Scott J. Horowitz, NASA Associate Administrator for Exploration Systems announce to NASA employees and members of the media the responsibilities of the NASA centers associated with the Constellation Program for robotic and human Moon and Mars exploration on Wednesday, June 5, 2006, at NASA Headquarters in Washington. Photo Credit: (NASA/Bill Ingalls)

Constellation Program Press Conference

NASA Image and Video Library

2006-06-04

NASA Administrator Michael Griffin, left, Scott Horowitz, NASA Associate Administrator for Exploration Systems and Jeff Hanley, Constellation Program Manager, right, are seen during a press conference outlining specific center responsibilities associated with the Constellation Program for robotic and human Moon and Mars exploration, Monday, June 5, 2006, at NASA Headquarters in Washington. Photo Credit (NASA/Bill Ingalls)

Constellation Program Press Conference

NASA Image and Video Library

2006-06-04

Members of the media listen during a press conference with NASA Administrator Michael Griffin, Scott Horowitz, NASA Associate Administrator for Exploration Systems and Jeff Hanley, Constellation Program Manager, outlining specific center responsibilities associated with the Constellation Program for robotic and human Moon and Mars exploration, Monday, June 5, 2006, at NASA Headquarters in Washington. Photo Credit (NASA/Bill Ingalls)

Constellation Program Update

NASA Image and Video Library

2006-06-04

Scott J. Horowitz, NASA Associate Administrator for Exploration Systems, left, and Jeff Hanley, Constellation Program Manager, announce to NASA employees and members of the media the responsibilities of the NASA centers associated with the Constellation Program for robotic and human Moon and Mars exploration on Wednesday, June 5, 2006, at NASA Headquarters in Washington. Photo Credit: (NASA/Bill Ingalls)

On the feasibility of monitoring carbon monoxide in the lower troposphere from a constellation of Northern Hemisphere geostationary satellites. (Part 1)

NASA Astrophysics Data System (ADS)

Barré, Jérôme; Edwards, David; Worden, Helen; Da Silva, Arlindo; Lahoz, William

2015-07-01

By the end of the current decade, there are plans to deploy several geostationary Earth orbit (GEO) satellite missions for atmospheric composition over North America, East Asia and Europe with additional missions proposed. Together, these present the possibility of a constellation of geostationary platforms to achieve continuous time-resolved high-density observations over continental domains for mapping pollutant sources and variability at diurnal and local scales. In this paper, we use a novel approach to sample a very high global resolution model (GEOS-5 at 7 km horizontal resolution) to produce a dataset of synthetic carbon monoxide pollution observations representative of those potentially obtainable from a GEO satellite constellation with predicted measurement sensitivities based on current remote sensing capabilities. Part 1 of this study focuses on the production of simulated synthetic measurements for air quality OSSEs (Observing System Simulation Experiments). We simulate carbon monoxide nadir retrievals using a technique that provides realistic measurements with very low computational cost. We discuss the sampling methodology: the projection of footprints and areas of regard for geostationary geometries over each of the North America, East Asia and Europe regions; the regression method to simulate measurement sensitivity; and the measurement error simulation. A detailed analysis of the simulated observation sensitivity is performed, and limitations of the method are discussed. We also describe impacts from clouds, showing that the efficiency of an instrument making atmospheric composition measurements on a geostationary platform is dependent on the dominant weather regime over a given region and the pixel size resolution. These results demonstrate the viability of the ;instrument simulator; step for an OSSE to assess the performance of a constellation of geostationary satellites for air quality measurements. We describe the OSSE results in a follow up paper (Part 2 of this study).

Best Practices for Operations of Satellite Constellations

NASA Technical Reports Server (NTRS)

Howard, Joseph; Oza, Dipak; Smith, Danford S.

2006-01-01

This paper presents the best practices used by several commercial and government operators of satellite constellations. These best practices were identified through a series of seminars and discussions held at NASA Goddard Space Flight Center (GSFC). The best practices are arrived through many years of experience and improvements made in the operations procedures and the operational systems with the primary drivers as mission safety and cost effectiveness. This paper discusses the operational aspects associated with how different organizations manage complexities of constellation operations. For the purposes of this paper, satellite constellations are groups of similar spacecraft with more than one spacecraft needed to fully accomplish the constellation's mission

Alaska Athabascan stellar astronomy

NASA Astrophysics Data System (ADS)

Cannon, Christopher M.

2014-01-01

Stellar astronomy is a fundamental component of Alaska Athabascan cultures that facilitates time-reckoning, navigation, weather forecasting, and cosmology. Evidence from the linguistic record suggests that a group of stars corresponding to the Big Dipper is the only widely attested constellation across the Northern Athabascan languages. However, instruction from expert Athabascan consultants shows that the correlation of these names with the Big Dipper is only partial. In Alaska Gwich'in, Ahtna, and Upper Tanana languages the Big Dipper is identified as one part of a much larger circumpolar humanoid constellation that spans more than 133 degrees across the sky. The Big Dipper is identified as a tail, while the other remaining asterisms within the humanoid constellation are named using other body part terms. The concept of a whole-sky humanoid constellation provides a single unifying system for mapping the night sky, and the reliance on body-part metaphors renders the system highly mnemonic. By recognizing one part of the constellation the stargazer is immediately able to identify the remaining parts based on an existing mental map of the human body. The circumpolar position of a whole-sky constellation yields a highly functional system that facilitates both navigation and time-reckoning in the subarctic. Northern Athabascan astronomy is not only much richer than previously described; it also provides evidence for a completely novel and previously undocumented way of conceptualizing the sky---one that is unique to the subarctic and uniquely adapted to northern cultures. The concept of a large humanoid constellation may be widespread across the entire subarctic and have great antiquity. In addition, the use of cognate body part terms describing asterisms within humanoid constellations is similarly found in Navajo, suggesting a common ancestor from which Northern and Southern Athabascan stellar naming strategies derived.

Coordination and Cooperation to Achieve the GEOSS Space Segment: A Systems Approach

NASA Technical Reports Server (NTRS)

Killough, Brian D., Jr.

2007-01-01

Established in April 2007, the SEO has made significant accomplishments in the support of CEOS and the virtual constellations. These accomplishments include (1) constellation trade studies for Atmospheric Composition and Land Surface Imaging, (2) a new engineering framework for requirements definition, assessment and architecture planning, (3) completion of a draft requirements document and gap analysis for the Atmospheric Composition Virtual Constellation, and (4) the development of a DVD video highlighting CEOS and the Virtual Constellation concept.

Infusing Stretch Goal Requirements into the Constellation Program

NASA Technical Reports Server (NTRS)

Lee, Young H.; Galpin, Roger A.; Ingoldsby, Kevin

2008-01-01

In 2004, the Vision for Space Exploration (VSE) was announced by the United States President's Administration in an effort to explore space and to extend a human presence across our solar system. Subsequently, the National Aeronautics and Space Administration (NASA) established the Exploration Systems Mission Directorate (ESMD) to develop a constellation of new capabilities, supporting technologies, and foundational research that allows for the sustained and affordable exploration of space. Then, ESMD specified the primary mission for the Constellation Program to carry out a series of human expeditions, ranging from Low Earth Orbit (LEO) to the surface of Moon, Mars, and beyond for the purposes of conducting human exploration of space. Thus, the Constellation Program was established at the Lyndon B. Johnson Space Center (JSC) to manage the development of the flight and ground infrastructure and systems that can enable continued and extended human access to space. Constellation Program's "Design Objectives" call for an early attention to the program's life cycle costs management through the Program's Need, Goals, and Objectives (NGO) document, which provides the vision, scope, and key areas of focus for the Program. One general policy of the Constellation Program, found in the Constellation Architecture Requirements Document (CARD), states: "A sustainable program hinges on how effectively total life cycle costs are managed. Developmental costs are a key consideration, but total life cycle costs related to the production, processing, and operation of the entire architecture must be accounted for in design decisions sufficiently to ensure future resources are available for ever more ambitious missions into the solar system....It is the intent of the Constellation Program to aggressively manage this aspect of the program using the design policies and simplicity." To respond to the Program's strong desire to manage the program life cycle costs, special efforts were established to identify operability requirements to influence flight vehicle and ground infrastructure design in order to impact the life cycle operations costs, and stretch goal requirements were introduced to the Program. This paper will describe how these stretch goal requirements were identified, developed, refined, matured, approved, and infused into the CARD. The paper will also document several challenges encountered when infusing the stretch goal requirements into the Constellation Program.

A unique constellation of spacecraft constellations to study Kelvin-Helmholtz Instability in 2017-2020: MMS, Cluster and Themis

NASA Astrophysics Data System (ADS)

Masson, A.; Nykyri, K.

2017-12-01

The Cluster and the Themis missions have shed a total new light on the Kelvin-Helmholtz Instability (KHI) mechanism at the magnetopause. To name a few, these missions have enabled the observation of KHI rolled-up vortices, for the first time with four spacecraft (Hasegawa et al., 2004). They revealed its presence under any Interplanetary Magnetic Field (IMF) conditions (Hwang et al., 2011, 2012). They also revealed that their occurence may have been largely underestimated (Kavosi and Raeder, 2015). Very recently, the presence of ion magnetosonic waves with sufficient energy to account for the observed level of ion heating within a KHI vortex may be the first evidence of cross-scale energy transport (Moore et al., 2016). After presenting some the main highlights of Cluster and Themis on this phenomenon, we will present upcoming new observations with MMS, Cluster and Themis in 2017-2020 timeframe. Together, they will form a unique constellation of spacecraft constellations to study this phenomenon for the first time. We will present some of the key scientific questions these new data will enable to tackle.

Requirements and Sizing Investigation for the Constellation Space Suit Portable Life Support System Trace Contaminant Control

NASA Technical Reports Server (NTRS)

Jennings, Mallory A.; Paul, Heather L.; Waguespack, Glenn M.

2010-01-01

This presentation summarized the results of a trade study that evaluated whether trace contaminant control within the Constellation Spacesuit PLSS could be achieved without a Trace Contaminant Control System (TCCS) by relying on suit leakage, ullage loss from the carbon dioxide and humidity control system, and other factors. Mallory Jennings and Dr. Glenn Waguespack studied trace contaminant generation rates to verify that values reflected the latest designs for Constellation spacesuit system pressure garment materials and PLSS hardware. They also calculated TCCS sizing and conducted a literature survey to review the latest developments in trace contaminant technologies.

Positioning stability improvement with inter-system biases on multi-GNSS PPP

NASA Astrophysics Data System (ADS)

Choi, Byung-Kyu; Yoon, Hasu

2018-07-01

The availability of multiple signals from different Global Navigation Satellite System (GNSS) constellations provides opportunities for improving positioning accuracy and initial convergence time. With dual-frequency observations from the four constellations (GPS, GLONASS, Galileo, and BeiDou), it is possible to investigate combined GNSS precise point positioning (PPP) accuracy and stability. The differences between GNSS systems result in inter-system biases (ISBs). We consider several ISB values such as GPS-GLONASS, GPS-Galileo, and GPS-BeiDou. These biases are compliant with key parameters defined in the multi-GNSS PPP processing. In this study, we present a unified PPP method that sets ISB values as fixed or constant. A comprehensive analysis that includes satellite visibility, position dilution of precision, position accuracy is performed to evaluate a unified PPP method with constrained cut-off elevation angles. Compared to the conventional PPP solutions, our approach shows more stable positioning at a constrained cut-off elevation angle of 50 degrees.

ONLINE WATER MONITORING UTILIZING AN AUTOMATED MICROARRAY BIOSENSOR INSTRUMENT - PHASE I

EPA Science Inventory

Constellation Technology Corporation (Constellation) proposes the use of an integrated recovery and detection system for online water supply monitoring.  The integrated system is designed to efficiently capture and recover pathogens such as bacteria, viruses, parasites, an...

Three Corner Sat Communications System

NASA Technical Reports Server (NTRS)

Anderson, Bobby; Horan, Stephen

2000-01-01

Three Corner Satellite is a constellation of three nanosatellites designed and built by students. New Mexico State University has taken on the design of the communications system for this constellation. The system includes the forward link, return link, and the crosslink. Due to size, mass, power, and financial constraints, we must design a small, light, power efficient, and inexpensive communications system. This thesis presents the design of a radio system to accomplish the data transmission requirements in light of the system constraints. In addition to the hardware design, the operational commands needed by the satellite's on-board computer to control and communicate with the communications hardware will be presented. In order for the hardware to communicate with the ground stations, we will examine the link budgets derived from the radiated power of the transmitters, link distance, data modulation, and data rate for each link. The antenna design for the constellation is analyzed using software and testing the physical antennas on a model satellite. After the analysis and testing, a combination of different systems will meet and exceed the requirements and constraints of the Three Corner Satellite constellation.

Constellation Program Update

NASA Image and Video Library

2006-06-04

NASA Administrator Michael Griffin, left, Scott J. Horowitz, NASA Associate Administrator for Exploration Systems and Jeff Hanley, Constellation Program Manager, right, announce to NASA employees and members of the media the responsibilities of the NASA centers associated with the Constellation Program for robotic and human Moon and Mars exploration on Wednesday, June 5, 2006, at NASA Headquarters in Washington. Photo Credit: (NASA/Bill Ingalls)

Constellation Program Press Conference

NASA Image and Video Library

2006-06-04

Dean Acosta, NASA Deputy Assistant Administrator and Press Secretary, moderates a press conference with NASA Administrator Michael Griffin Scott Horowitz, NASA Associate Administrator for Exploration Systems and Jeff Hanley, Constellation Program Manager, outlining specific center responsibilities associated with the Constellation Program for robotic and human Moon and Mars exploration, Monday, June 5, 2006, at NASA Headquarters in Washington. Photo Credit (NASA/Bill Ingalls)

The NASA Constellation Program Procedure System

NASA Technical Reports Server (NTRS)

Phillips, Robert G.; Wang, Lui

2010-01-01

NASA has used procedures to describe activities to be performed onboard vehicles by astronaut crew and on the ground by flight controllers since Apollo. Starting with later Space Shuttle missions and the International Space Station, NASA moved forward to electronic presentation of procedures. For the Constellation Program, another large step forward is being taken - to make procedures more interactive with the vehicle and to assist the crew in controlling the vehicle more efficiently and with less error. The overall name for the project is the Constellation Procedure Applications Software System (CxPASS). This paper describes some of the history behind this effort, the key concepts and operational paradigms that the work is based upon, and the actual products being developed to implement procedures for Constellation

Global Precipitation Measurement (GPM) launch, commissioning, and early operations

NASA Astrophysics Data System (ADS)

Neeck, Steven P.; Kakar, Ramesh K.; Azarbarzin, Ardeshir A.; Hou, Arthur Y.

2014-10-01

The Global Precipitation Measurement (GPM) mission is an international partnership co-led by NASA and the Japan Aerospace Exploration Agency (JAXA). The mission centers on the GPM Core Observatory and consists of an international network, or constellation, of additional satellites that together will provide next-generation global observations of precipitation from space. The GPM constellation will provide measurements of the intensity and variability of precipitation, three-dimensional structure of cloud and storm systems, the microphysics of ice and liquid particles within clouds, and the amount of water falling to Earth's surface. Observations from the GPM constellation, combined with land surface data, will improve weather forecast models; climate models; integrated hydrologic models of watersheds; and forecasts of hurricanes/typhoons/cylcones, landslides, floods and droughts. The GPM Core Observatory carries an advanced radar/radiometer system and serves as a reference standard to unify precipitation measurements from all satellites that fly within the constellation. The GPM Core Observatory improves upon the capabilities of its predecessor, the NASA-JAXA Tropical Rainfall Measuring Mission (TRMM), with advanced science instruments and expanded coverage of Earth's surface. The GPM Core Observatory carries two instruments, the NASA-supplied GPM Microwave Imager (GMI) and the JAXA-supplied Dual-frequency Precipitation Radar (DPR). The GMI measures the amount, size, intensity and type of precipitation, from heavy-tomoderate rain to light rain and snowfall. The DPR provides three-dimensional profiles and intensities of liquid and solid precipitation. The French Centre National d'Études Spatiales (CNES), the Indian Space Research Organisation (ISRO), the U.S. National Oceanic and Atmospheric Administration (NOAA), the European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT), and the U.S. Department of Defense are partners with NASA and JAXA. The GPM Core Observatory was launched from JAXA's Tanegashima Space Center on an H-IIA launch vehicle on February 28, 2014 Japan Standard Time (JST). The mission has completed its checkout and commissioning phase and is in Operations Phase. The current status and early results will be discussed.

Satellite Constellations for Space Weather and Ionospheric Studies: Overview of the COSMIC and COSMIC-2 Missions

NASA Astrophysics Data System (ADS)

Schreiner, W. S.; Pedatella, N. M.; Weiss, J.

2016-12-01

Measurements from constellations of low Earth orbiting (LEO) satellites are proving highly useful for ionospheric science and space weather studies. The Constellation Observing System for Meteorology Ionosphere and Climate (COSMIC), a joint US/Taiwan mission launched in April 2006, is a six micro-satellite constellation carrying Global Positioning System (GPS) radio occultation (RO) receivers. COSMIC has collected a large amount of useful data from these scientific payloads and is still currently collecting up to 1,000 RO measurement events per day on average. The GPS RO dual-frequency L-band phase and amplitude measurements can be used to observe absolute Total Electron Content (TEC) and scintillation on lines of sight between the LEO and GPS satellites, and electron density profiles via the RO method. The large number and complete global and local time coverage of COSMIC data are allowing scientists to observe ionospheric and plasmaspheric phenomena that are difficult to see with other instruments. The success of COSMIC has prompted U.S. agencies and Taiwan to execute a COSMIC follow-on mission (called COSMIC-2) that will put twelve satellites with GNSS (Global Navigation Satellite System) RO payloads into orbit on two launches in the 2017-20 time frame. The first launch in 2017 will place six satellites in a 520-km altitude 24 deg inclination orbit, which is ideal for low latitude ionospheric research and space weather forecasting. The planned second launch (not currently funded) places six additional satellites in a 750 km 72 deg inclination orbit to provide global coverage and increased sampling density. COSMIC-2 will make use of an advanced radio occultation receiver with an innovative beam-forming antenna design, and is expected to produce at least 10,000 high-quality atmospheric and ionospheric profiles per day from GPS and GLONASS signals to support operational weather prediction, climate monitoring, and space weather forecasting. Each COSMIC-2 spacecraft in the first launch will also carry additional space weather payloads: a tri-band RF Beacon transmitter, and an Ion Velocity Meter instrument. This presentation will provide a short summary of the COSMIC mission and then present an overview of the COSMIC-2 mission, including expected data product performance and science goals

The NASA CYGNSS Satellite Constellation for Tropical Cyclone Observations

NASA Astrophysics Data System (ADS)

Ruf, C. S.; Provost, D.; Rose, R.; Scherrer, J.; Atlas, R. M.; Chang, P.; Clarizia, M. P.; Garrison, J. L.; Gleason, S.; Katzberg, S. J.; Jelenak, Z.; Johnson, J. T.; Majumdar, S.; O'Brien, A.; Posselt, D. J.; Ridley, A. J.; Said, F.; Soisuvarn, S.; Zavorotny, V. U.

2016-12-01

The NASA Cyclone Global Navigation Satellite System (CYGNSS) is scheduled for launch in November 2016 to study the surface wind structure in and near the inner core of tropical cyclones. CYGNSS consists of a constellation of eight observatories carried into orbit on a single launch vehicle. Each observatory carries a 4-channel bistatic radar receiver tuned to receive GPS navigation signals scattered from the ocean surface. The eight satellites are spaced approximately twelve minutes apart in a common circular, low inclination orbit plane to provide frequent temporal sampling in the tropics. The 35deg orbit inclination results in coverage of the full globe between 38deg N and 38deg S latitude with a median(mean) revisit time of 3(7) hours The 32 CYGNSS radars operate in L-Band at a wavelength of 19 cm. This allows for adequate penetration to enable surface wind observations under all levels of precipitation, including those encountered in the inner core and eyewall of tropical cyclones. The combination of operation unaffected by heavy precipitation together with high temporal resolution throughout the life cycle of storms is expected to support significant improvements in the forecast skill of storm track and intensity, as well as better situational awareness of the extent and structure of storms in near real time. A summary of the properties of the CYGNSS science data products will be presented, together with an update on the results of ongoing Observation System Simulation Experiments performed by members of the CYGNSS science team over the past four years, in particular addressing the expected impact on storm track and intensity forecast skill. With launch scheduled for the month prior to AGU, the on orbit status of the constellation will also be presented.

Utilizing new GNSS capabilities for exploring Geospace

NASA Astrophysics Data System (ADS)

Coster, A. J.

2015-12-01

In 2000 the density of GPS receivers across the continental United States increased to the point that strictly data-driven regional maps of total electron content (TEC) could be constructed. These data-driven maps allowed the TEC to be monitored throughout the course of geomagnetic storms and to observe the progression of traveling ionospheric disturbances. This allowed studies of the development of storm enhanced density plumes in both hemispheres and of the dynamic changes in the equatorial TEC following stratospheric warming events. Currently, GPS TEC maps have become recognized as one of the premier tools to monitor coupling of atmospheric regions from both below and above the ionosphere. The number of available scientific dual-frequency receivers across the globe now exceeds 3000. However this number is anticipated to increase rapidly in part due to the numerous arrays being fielded for commercial applications such as precision farming and highway surveying. In addition, there will be a rapid increase in the number of GNSS signals available in the near future. Besides GPS, the European Union is building a system named GALILEO, which will consist of a 30-satellite constellation. The Russians have a system based on a 24-satellite constellation named GLONASS. The Chinese are developing a system called Beidou, which means "stars of the Big Dipper". The Beidou system will consist of 35 satellites. By 2023, there will be more than 160 GNSS satellites and 400 signals. Multi-constellation, multi-band GNSS will be a major enabler for space weather studies. This talk will focus on the potential of using the multiple new GNSS signals and the new higher density receiver arrays for measurements of plasma drift, detailed studies of traveling ionospheric disturbances (TIDS) and expanded studies of atmospheric coupling. We will conclude by describing the tremendous potential of merging GNSS observations with observations collected by arrays of low-cost, low-power, and small form factor ionosondes. In the future, we predict that new ionosonde and GNSS receiver networks will enable unprecedented mesoscale real-time tomographic observations of the ionosphere.

β Lup, δ Lup, and τ^1 Lup observed by BRITE-Constellation

NASA Astrophysics Data System (ADS)

Cugier, H.; Pigulski, A.

2017-09-01

Time-series analysis of BRITE-Constellation photometry of β Lup, δ Lup and τ^1 Lup revealed 16, 22 and four pulsation modes, respectively. An attempt to constrain internal structure of these stars via seismic modelling was also made.

JPRS Report, Science & Technology, USSR: Space

DTIC Science & Technology

1988-02-26

data on short-wave length radiation of galaxies. Areas in the constellations Puppis and Andromeda have been selected as objects of observations...the days just past, and photographing of individual sections of the constellation Triangulum and the Andromeda Nebula is planned for today. Both

Sensor Webs to Constellations

NASA Astrophysics Data System (ADS)

Cole, M.

2017-12-01

Advanced technology plays a key role in enabling future Earth-observing missions needed for global monitoring and climate research. Rapid progress over the past decade and anticipated for the coming decades have diminished the size of some satellites while increasing the amount of data and required pace of integration and analysis. Sensor web developments provide correlations to constellations of smallsats. Reviewing current advances in sensor webs and requirements for constellations will improve planning, operations, and data management for future architectures of multiple satellites with a common mission goal.

Constellation Program Update

NASA Image and Video Library

2006-06-04

Jeff Hanley, Constellation Program Manager, right, announces to NASA employees and members of the media the responsibilities of the NASA centers associated with the Constellation Program for robotic and human Moon and Mars exploration on Wednesday, June 5, 2006, at NASA Headquarters in Washington. Hanley is joined by Scott J. Horowitz, NASA Associate Administrator for Exploration Systems and NASA Administrator Michael Griffin, left. Photo Credit: (NASA/Bill Ingalls)

Constellation Program Update

NASA Image and Video Library

2006-06-04

NASA Administrator Michael Griffin, left, announces to NASA employees and members of the media the responsibilities of the NASA centers associated with the Constellation Program for robotic and human Moon and Mars exploration on Wednesday, June 5, 2006, at NASA Headquarters in Washington. He is joined by Scott J. Horowitz, NASA Associate Administrator for Exploration Systems and Jeff Hanley, Constellation Program Manager, right. Photo Credit: (NASA/Bill Ingalls)

Constellation Program Update

NASA Image and Video Library

2006-06-04

Scott J. Horowitz, NASA Associate Administrator for Exploration Systems, center, announces to NASA employees and members of the media the responsibilities of the NASA centers associated with the Constellation Program for robotic and human Moon and Mars exploration on Wednesday, June 5, 2006, at NASA Headquarters in Washington. Horowitz was joined by NASA Administrator Michael Griffin, left, and Jeff Hanley, Constellation Program Manager. Photo Credit: (NASA/Bill Ingalls)

Requirements and Sizing Investigation for Constellation Space Suit Portable Life Support System Trace Contaminant Control

NASA Technical Reports Server (NTRS)

Paul, Heather L.; Jennings, Mallory A.; Waguespack, Glenn

2010-01-01

The Trace Contaminant Control System (TCCS), located within the ventilation loop of the Constellation Space Suit Portable Life Support System (PLSS), is responsible for removing hazardous trace contaminants from the space suit ventilation flow. This paper summarizes the results of a trade study that evaluated if trace contaminant control could be accomplished without a TCCS, relying on suit leakage, ullage loss from the carbon dioxide and humidity control system, and other factors. Trace contaminant generation rates were revisited to verify that values reflect the latest designs for Constellation Space Suit System (CSSS) pressure garment materials and PLSS hardware. Additionally, TCCS sizing calculations were performed and a literature survey was conducted to review the latest developments in trace contaminant technologies.

The DUBAISAT-2/DEIMOS-2 constellation: public-private cooperation between Emirates and Spain

NASA Astrophysics Data System (ADS)

Pirondini, Fabrizio; Al Marri, Salem

2014-10-01

The Emirates Institution for Advanced Science and Technology (EIAST) was established by the Dubai Government in 2006 with the goal of promoting a culture of advanced scientific research and technology innovation in Dubai and the UAE, and enhancing technology innovation and scientific skills among UAE nationals. EIAST launched in November 2013 the DubaiSat-2, its second Earth Observation satellite, and the first to provide VHR multispectral imagery. The satellite has successfully completed its in-orbit commissioning and it is now fully operational. ELECNOR DEIMOS is a private Spanish company, part of the Elecnor industrial group, which owns and operates DEIMOS-1, the first Spanish Earth Observation satellite, launched in 2009. ELECNOR DEIMOS launched in June 2014 its second satellite, DEIMOS-2, a VHR, agile satellite capable of providing 4-bands multispectral imagery. The whole end-to-end DEIMOS- 2 system has been designed to provide a cost-effective and highly responsive service to cope with the increasing need of fast access to VHR imagery. The two satellites, with a mass of 300 kg each, were developed in cooperation with Satrec-I (South Korea), and are based on the SpaceEye-1 platform. The two satellites have an identical payload, and produce 75- cm resolution pan-sharpened imagery across a 12-km swath. Together, they have a combined collection capacity of more than 300,000 sqkm per day. EIAST and ELECNOR DEIMOS have set up a unique, trans-national public-private partnership to operate the two satellites as a constellation, jointly commercialize the imagery of both satellites, and interchange technical and operational information to increase the efficiency of both systems. The operations of the constellation are based on four ground stations: Al Khawaneej (Dubai), Puertollano (Spain), Kiruna (Sweden) and Inuvik (Canada), which assure at least a contact per orbit with each satellite. The constellation functionalities of the ground segment were developed by EIAST and ELECNOR DEIMOS in cooperation, in order to provide a product which is exactly the same, independently of which satellite acquired the image. This paper describes the main features of the DubaiSat-2 and DEIMOS-2 systems, their combined use in constellation, and the products and services jointly offered to public and private customers worldwide. Moreover, it describes the cooperation agreement between EIAST and ELECNOR DEIMOS, and provides an update of the operational status of both missions at the time of writing.

Teledesic Global Wireless Broadband Network: Space Infrastructure Architecture, Design Features and Technologies

NASA Technical Reports Server (NTRS)

Stuart, James R.

1995-01-01

The Teledesic satellites are a new class of small satellites which demonstrate the important commercial benefits of using technologies developed for other purposes by U.S. National Laboratories. The Teledesic satellite architecture, subsystem design features, and new technologies are described. The new Teledesic satellite manufacturing, integration, and test approaches which use modern high volume production techniques and result in surprisingly low space segment costs are discussed. The constellation control and management features and attendant software architecture features are addressed. After briefly discussing the economic and technological impact on the USA commercial space industries of the space communications revolution and such large constellation projects, the paper concludes with observations on the trend toward future system architectures using networked groups of much smaller satellites.

Space and ground segment performance of the FORMOSAT-3/COSMIC mission: four years in orbit

NASA Astrophysics Data System (ADS)

Fong, C.-J.; Whiteley, D.; Yang, E.; Cook, K.; Chu, V.; Schreiner, B.; Ector, D.; Wilczynski, P.; Liu, T.-Y.; Yen, N.

2011-01-01

The FORMOSAT-3/COSMIC (Constellation Observing System for Meteorology, Ionosphere, and Climate) mission consisting of six Low-Earth-Orbit (LEO) satellites is the world's first demonstration constellation using radio occultation signals from Global Positioning System (GPS) satellites. The radio occultation signals are retrieved in near real-time for global weather/climate monitoring, numerical weather prediction, and space weather research. The mission has processed on average 1400 to 1800 high-quality atmospheric sounding profiles per day. The atmospheric radio occultation soundings data are assimilated into operational numerical weather prediction models for global weather prediction, including typhoon/hurricane/cyclone forecasts. The radio occultation data has shown a positive impact on weather predictions at many national weather forecast centers. A proposed follow-on mission transitions the program from the current experimental research system to a significantly improved real-time operational system, which will reliably provide 8000 radio occultation soundings per day. The follow-on mission as planned will consist of 12 satellites with a data latency of 45 min, which will provide greatly enhanced opportunities for operational forecasts and scientific research. This paper will address the FORMOSAT-3/COSMIC system and mission overview, the spacecraft and ground system performance after four years in orbit, the lessons learned from the encountered technical challenges and observations, and the expected design improvements for the new spacecraft and ground system.

Analysis For Monitoring the Earth Science Afternoon Constellation

NASA Technical Reports Server (NTRS)

Demarest, Peter; Richon, Karen V.; Wright, Frank

2005-01-01

The Earth Science Afternoon Constellation consists of Aqua, Aura, PARASOL, CALIPSO, Cloudsat, and the Orbiting Carbon Observatory (OCO). The coordination of flight dynamics activities between these missions is critical to the safety and success of the Afternoon Constellation. This coordination is based on two main concepts, the control box and the zone-of-exclusion. This paper describes how these two concepts are implemented in the Constellation Coordination System (CCS). The CCS is a collection of tools that enables the collection and distribution of flight dynamics products among the missions, allows cross-mission analyses to be performed through a web-based interface, performs automated analyses to monitor the overall constellation, and notifies the missions of changes in the status of the other missions.

Launching Science: Science Opportunities Provided by NASA's Constellation System

NASA Technical Reports Server (NTRS)

2008-01-01

In 2004 NASA began implementation of the first phases of a new space exploration policy. This implementation effort included the development of a new human-carrying spacecraft, known as Orion; the Altair lunar lander; and two new launch vehicles, the Ares I and Ares V rockets.collectively called the Constellation System (described in Chapter 5 of this report). The Altair lunar lander, which is in the very preliminary concept stage, is not discussed in detail in the report. In 2007 NASA asked the National Research Council (NRC) to evaluate the science opportunities enabled by the Constellation System. To do so, the NRC established the Committee on Science Opportunities Enabled by NASA's Constellation System. In general, the committee interpreted "Constellation-enabled" broadly, to include not only mission concepts that required Constellation, but also those that could be significantly enhanced by Constellation. The committee intends this report to be a general overview of the topic of science missions that might be enabled by Constellation, a sort of textbook introduction to the subject. The mission concepts that are reviewed in this report should serve as general examples of kinds of missions, and the committee s evaluation should not be construed as an endorsement of the specific teams that developed the mission concepts or of their proposals. Additionally, NASA has a well-developed process for establishing scientific priorities by asking the NRC to conduct a "decadal survey" for a particular discipline. Any scientific mission that eventually uses the Constellation System will have to be properly evaluated by means of this decadal survey process. The committee was impressed with the scientific potential of many of the proposals that it evaluated. However, the committee notes that the Constellation System has been justified by NASA and selected in order to enable human exploration beyond low Earth orbit.not to enable science missions. Virtually all of the science mission concepts that could take advantage of Constellation s unique capabilities are likely to be prohibitively expensive. Several times in the past NASA has begun ambitious space science missions that ultimately proved too expensive for the agency to pursue. Examples include the Voyager-Mars mission and the Prometheus program and its Jupiter Icy Moons Orbiter spacecraft (both examples are discussed in Chapter 1). Finding: The scientific missions reviewed by the committee as appropriate for launch on an Ares V vehicle fall, with few exceptions, into the "flagship" class of missions. The preliminary cost estimates, based on mission concepts that at this time are not very detailed, indicate that the costs of many of the missions analyzed will be above $5 billion (in current dollars). The Ares V costs are not included in these estimates. All of the costs discussed in this report are presented in current-year (2008) dollars, not accounting for potential inflation that could occur between now and the decade in which these missions might be pursued. In general, preliminary cost estimates for proposed missions are, for many reasons, significantly lower than the final costs. Given the large cost estimates for many of the missions assessed in this report, the potentially large impacts on NASA's budget by many of these missions are readily apparent.

GLADIS: GLobal AIS & Data-X International Satellite Constellation

DTIC Science & Technology

2008-01-01

1Approved for public release; distribution is unlimited GLADIS : GLobal AIS & Data-X International Satellite Constellation Space-Based System for...TYPE N/A 3. DATES COVERED - 4. TITLE AND SUBTITLE GLADIS : GLobal AIS & Data-X International Satellite Constellation 5a. CONTRACT NUMBER 5b...Maritime & Technology Challenges • GLADIS Mission Objective • AIS & Data-X capabilities • GLADIS Architecture • International Strategy – MSSIS as Model

Global Precipitation Measurement (GPM) Mission: Overview and Status

NASA Technical Reports Server (NTRS)

Hou, Arthur Y.

2012-01-01

The Global Precipitation Measurement (GPM) Mission is an international satellite mission specifically designed to unify and advance precipitation measurements from a constellation of research and operational microwave sensors. NASA and JAXA will deploy a Core Observatory in 2014 to serve as a reference satellite to unify precipitation measurements from the constellation of sensors. The GPM Core Observatory will carry a Ku/Ka-band Dual-frequency Precipitation Radar (DPR) and a conical-scanning multi-channel (10-183 GHz) GPM Microwave Radiometer (GMI). The DPR will be the first dual-frequency radar in space to provide not only measurements of 3-D precipitation structures but also quantitative information on microphysical properties of precipitating particles. The DPR and GMI measurements will together provide a database that relates vertical hydrometeor profiles to multi-frequency microwave radiances over a variety of environmental conditions across the globe. This combined database will be used as a common transfer standard for improving the accuracy and consistency of precipitation retrievals from all constellation radiometers. For global coverage, GPM relies on existing satellite programs and new mission opportunities from a consortium of partners through bilateral agreements with either NASA or JAXA. Each constellation member may have its unique scientific or operational objectives but contributes microwave observations to GPM for the generation and dissemination of unified global precipitation data products. In addition to the DPR and GMI on the Core Observatory, the baseline GPM constellation consists of the following sensors: (1) Special Sensor Microwave Imager/Sounder (SSMIS) instruments on the U.S. Defense Meteorological Satellite Program (DMSP) satellites, (2) the Advanced Microwave Scanning Radiometer-2 (AMSR-2) on the GCOM-W1 satellite of JAXA, (3) the Multi-Frequency Microwave Scanning Radiometer (MADRAS) and the multi-channel microwave humidity sounder (SAPHIR) on the French-Indian MeghaTropiques satellite, (4) the Microwave Humidity Sounder (MHS) on the National Oceanic and Atmospheric Administration (NOAA)-19, (5) MHS instruments on MetOp satellites launched by the European Organization for the Exploitation of Meteorological Satellites (EUMETSAT), (6) the Advanced Technology Microwave Sounder (ATMS) on the National Polar-orbiting Operational Environmental Satellite System (NPOESS) Preparatory Project (NPP), and (7) ATMS instruments on the NOAA-NASA Joint Polar Satellite System (JPSS) satellites. Data from Chinese and Russian microwave radiometers may also become available through international collaboration under the auspices of the Committee on Earth Observation Satellites (CEOS) and Group on Earth Observations (GEO). The current generation of global rainfall products combines observations from a network of uncoordinated satellite missions using a variety of merging techniques. GPM will provide "next-generation" precipitation products characterized by: (1) more accurate instantaneous precipitation estimate (especially for light rain and cold-season solid precipitation), (2) intercalibrated microwave brightness temperatures from constellation radiometers within a consistent framework, and (3) unified precipitation retrievals from constellation radiometers using a common a priori hydrometeor database constrained by combined radar/radiometer measurements provided by the GPM Core Observatory. GPM is a science mission with integrated applications goals. GPM will provide a key measurement to improve understanding of global water cycle variability and freshwater availability in a changing climate. The DPR and GMI measurements will offer insights into 3-dimensional structures of hurricanes and midlatitude storms, microphysical properties of precipitating particles, and latent heat associated with precipitation processes. The GPM mission will also make data available in near realtime (within 3 hours of observations) forocietal applications ranging from position fixes of storm centers, numerical weather prediction, flood forecasting, freshwater management, landslide warning, crop prediction, to tracking of water-borne diseases. An overview of the GPM mission design, retrieval strategy, ground validation activities, and international science collaboration will be presented.

Precise orbit determination of BeiDou constellation based on BETS and MGEX network

PubMed Central

Lou, Yidong; Liu, Yang; Shi, Chuang; Yao, Xiuguang; Zheng, Fu

2014-01-01

Chinese BeiDou Navigation Satellite System is officially operational as a regional constellation with five Geostationary Earth Orbit (GEO) satellites, five Inclined Geosynchronous Satellite Orbit (IGSO) satellites and four Medium Earth Orbit (MEO) satellites. Observations from the BeiDou Experimental Tracking Stations (BETS) and the IGS Multi-GNSS Experiment (MGEX) network from 1 January to 31 March 2013 are processed for orbit determination of the BeiDou constellation. Various arc lengths and solar radiation pressure parameters are investigated. The reduced set of ECOM five-parameter model produces better performance than the full set of ECOM nine-parameter model for BeiDou IGSO and MEO. The orbit overlap for the middle days of 3-day arc solutions is better than 20 cm and 14 cm for IGSO and MEO in RMS, respectively. Satellite laser ranging residuals are better than 10 cm for both IGSO and MEO. For BeiDou GEO, the orbit overlap of several meters and satellite laser ranging residuals of several decimetres can be achieved. PMID:24733025

A SmallSat constellation mission architecture for a GRACE-type mission design

NASA Astrophysics Data System (ADS)

Deccia, C. M. A.; Nerem, R. S.; Yunck, T.

2017-12-01

The Gravity Recovery and Climate Experiment (GRACE) launched in 2002 and has been providing invaluable information of Earth's time-varying gravity field and GRACE-FO will continue this time series. For this work, we focus on architectures of future post-GRACE-FO like missions. Single pairs of satellites like GRACE and GRACE-FO are inherently limited in their spatio-temporal coverage. Full global coverage for a single pair can take up to 30 days for spatial resolutions of a few hundred kilometers, thus a single satellite pair is unable to observe sub-monthly signals in the Earth's time varying gravity field (e.g. hydrologic signals, etc.). Small satellite systems are becoming increasingly affordable and will soon allow a constellation of GRACE-type satellites to be deployed, with the capability to range between multiple satellites. Here, using simulation studies, we investigate the performance of such a constellation for different numbers of satellites (N) and different orbital configurations, in order to understand the improved performance that might be gained from such future mission architectures.

How Strong is the Case for Geostationary Hyperspectral Sounders?

NASA Astrophysics Data System (ADS)

Kirk-Davidoff, D. B.; Liu, Z.; Jensen, S.; Housley, E.

2014-12-01

The NASA GIFTS program designed and constructed a flight-ready hyperspectral infrared sounder for geostationary orbit. Efforts are now underway to launch a constellation of similar instruments. Salient characteristics included 4 km spatial resolution at nadir and 0.6 cm-1 spectral resolution in two infrared bands. Observing system experiments have demonstrated the success of assimilated hyperspectral infrared radiances from IASI and AIRS in improving weather forecast skill. These results provide circumstantial evidence that additional observations at higher spatial and temporal resolution would likely improve forecast skill further. However, there is only limited work investigating the magnitude of this skill improvement in the literature. Here we present a systematic program to quantify the additional skill of a constellation of geostationary hyperspectral sounders through observing system simulation experiments (OSSEs) using the WRF model and the WRFDA data assimilation system. The OSSEs will focus first on high-impact events, such as the forecast for Typhoon Haiyun, but will also address quotidian synoptic forecast skill. The focus will be on short-term forecast skill (<24 hours lead time), in accord with WRF's mesoscale design, and with the view that high time frequency observations are likely to make the biggest impact on the skill of short-range forecasts. The experiments will use as their starting point the full existing observational suite, so that additionality can be addressed, but will also consider contingencies, such as the loss of particular elements of the existing system, as well as the degree to which a stand-alone system of hyperspectral sounds would be able to successfully initialize a regional forecast model. A variety of settings, tropical and extratropical, marine and continental will be considered.

An integrated hyperspectral and SAR satellite constellation for environment monitoring

NASA Astrophysics Data System (ADS)

Wang, Jinnian; Ren, Fuhu; Xie, Chou; An, Jun; Tong, Zhanbo

2017-09-01

A fully-integrated, Hyperspectral optical and SAR (Synthetic Aperture Radar) constellation of small earth observation satellites will be deployed over multiple launches from last December to next five years. The Constellation is expected to comprise a minimum of 16 satellites (8 SAR and 8 optical ) flying in two orbital planes, with each plane consisting of four satellite pairs, equally-spaced around the orbit plane. Each pair of satellites will consist of a hyperspectral/mutispectral optical satellite and a high-resolution SAR satellite (X-band) flying in tandem. The constellation is expected to offer a number of innovative capabilities for environment monitoring. As a pre-launch experiment, two hyperspectral earth observation minisatellites, Spark 01 and 02 were launched as secondary payloads together with Tansat in December 2016 on a CZ-2D rocket. The satellites feature a wide-range hyperspectral imager. The ground resolution is 50 m, covering spectral range from visible to near infrared (420 nm - 1000 nm) and a swath width of 100km. The imager has an average spectral resolution of 5 nm with 148 channels, and a single satellite could obtain hyperspectral imagery with 2.5 million km2 per day, for global coverage every 16 days. This paper describes the potential applications of constellation image in environment monitoring.

The Global Precipitation Measurement (GPM) Mission: Overview and U.S. Science Status

NASA Astrophysics Data System (ADS)

Hou, Arthur Y.; Skofronick-Jackson, Gail; Stocker, Erich F.

2013-04-01

The Global Precipitation Measurement (GPM) Mission is a satellite mission specifically designed to unify and advance precipitation measurements from a constellation of research and operational microwave sensors provided by a consortium of international partners. NASA and JAXA will deploy a Core Observatory in 2014 to serve as a reference satellite for precipitation measurements by the constellation sensors. The GPM Core Observatory will carry a Ku/Ka-band Dual-frequency Precipitation Radar (DPR) and a conical-scanning multi-channel (10-183 GHz) GPM Microwave Radiometer (GMI). The DPR, the first dual-frequency radar in space, will provide not only measurements of 3-D precipitation structures but also quantitative information on microphysical properties of precipitating particles. The DPR and GMI measurements will together provide a database that relates vertical hydrometeor profiles to multi-frequency microwave radiances over a variety of environmental conditions across the globe. This combined database will serve as a common transfer standard for improving the accuracy and consistency of precipitation retrievals from all constellation radiometers. In addition to the Core Observatory, the GPM constellation consists of (1) Special Sensor Microwave Imager/Sounder (SSMIS) instruments on the U.S. Defense Meteorological Satellite Program (DMSP) satellites, (2) the Advanced Microwave Scanning Radiometer-2 (AMSR-2) on the GCOM-W1 satellite of JAXA, (3) the Multi-Frequency Microwave Scanning Radiometer (MADRAS) and the multi-channel microwave humidity sounder (SAPHIR) on the French-Indian Megha-Tropiques satellite, (4) the Microwave Humidity Sounder (MHS) on the National Oceanic and Atmospheric Administration (NOAA) Polar Orbiting Environmental Satellites (POES), (5) MHS instruments on MetOp satellites launched by the European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT), (6) the Advanced Technology Microwave Sounder (ATMS) on the National Polar-orbiting Operational Environmental Satellite System (NPOESS) Preparatory Project (NPP), and (7) ATMS instruments on the NOAA-NASA Joint Polar Satellite System (JPSS) satellites. Each constellation member may have its unique scientific or operational objectives but contributes microwave observations to GPM for the generation and dissemination of unified global precipitation data products. Currently global rainfall products combine observations from a network of uncoordinated satellite missions using a variety of merging techniques. GPM is designed to provide the next-generation of precipitation products characterized by: (1) more accurate instantaneous precipitation estimate (especially for light rain and cold-season solid precipitation), (2) intercalibrated microwave brightness temperatures from constellation radiometers within a consistent framework, and (3) unified precipitation retrievals from constellation radiometers using a common a priori hydrometeor database consistent with combined radar/radiometer measurements by the GPM Core Observatory. As a science mission with integrated applications goals, GPM will advance the understanding of global water cycle variability in a changing climate by offering insights into 3-dimensional structures of hurricanes and midlatitude storms, microphysical properties of precipitating particles, and latent heat associated with precipitation processes. The GPM Mission will also make data available in near realtime (within 3 hours of observations) for societal applications ranging from position fixes of storm centers, numerical weather prediction, flood forecasting, freshwater management, landslide warning, crop prediction, to tracking of water-borne diseases. This presentation will give an overview of the GPM mission and its development status approximately one-year prior to launch.

Discovery of the Lost Star Catalog of Hipparchus on the Farnese Atlas

NASA Astrophysics Data System (ADS)

Schaefer, B. E.

2004-12-01

Hipparchus was the greatest astronomer in Antiquity, with part of his reputation being based on his creation of the first star catalog around 129 BC. His star catalog has been since lost, although a few partial star positions are recorded in his only surviving work, the Commentary. Independently, a late Roman statue called the Farnese Atlas (now in Naples) has been known since the Middle Ages which records ancient Greek constellations. This marble statue shows the Titan Atlas kneeling on one knee while hold a large globe (65 cm in diameter) on one shoulder. This globe records 41 constellations accurately placed against a grid of reference circles, including the equator, tropics, colures, Arctic circle, and Antarctic circle. As the constellation positions shift over time (due to precession as discovered by Hipparchus), the position of the constellations on the Titan's globe will reveal the date of observations as ultimately used by the sculptor. Prior brief work on the globe has resulted in dates spread out over six centuries, with recent reviews only concluding that a thorough study is desperately needed. To fill this need, I have taken photographs appropriate for photogrammetry and have measured the positions of 70 points in the constellation figures and transformed these into RA and DEC in the globe's reference frame. A chi-square analysis then shows the date of the constellations to be 125 BC with a one-sigma uncertainty of 55 years. This date points directly at Hipparchus as being the observer and it strongly excludes all candidates that have been proposed over the past century (Aratus at c. 275 BC, Eudoxus at c. 366 BC, the original Assyrian observer at c. 1130 BC, and Ptolemy at AD 128). In addition, a very detailed comparison of the constellation figures and symbols on the Atlas' globe has been made with Hipparchus' Commentary, Aratus' (and Eudoxus') Phaenomena, Eratosthenes' Catasterismi, and Ptolemy's Almagest. I find essentially perfect agreement with Hipparchus' description of the sky (including many points unique to Hipparchus) with the Farnese Atlas; while all other ancient sources have many significant differences. In all, I have the very confident conclusion that the constellation figures on the Farnese Atlas are a depiction of Hipparchus' lost star catalog.

Test and Verification Approach for the NASA Constellation Program

NASA Technical Reports Server (NTRS)

Strong, Edward

2008-01-01

This viewgraph presentation is a test and verification approach for the NASA Constellation Program. The contents include: 1) The Vision for Space Exploration: Foundations for Exploration; 2) Constellation Program Fleet of Vehicles; 3) Exploration Roadmap; 4) Constellation Vehicle Approximate Size Comparison; 5) Ares I Elements; 6) Orion Elements; 7) Ares V Elements; 8) Lunar Lander; 9) Map of Constellation content across NASA; 10) CxP T&V Implementation; 11) Challenges in CxP T&V Program; 12) T&V Strategic Emphasis and Key Tenets; 13) CxP T&V Mission & Vision; 14) Constellation Program Organization; 15) Test and Evaluation Organization; 16) CxP Requirements Flowdown; 17) CxP Model Based Systems Engineering Approach; 18) CxP Verification Planning Documents; 19) Environmental Testing; 20) Scope of CxP Verification; 21) CxP Verification - General Process Flow; 22) Avionics and Software Integrated Testing Approach; 23) A-3 Test Stand; 24) Space Power Facility; 25) MEIT and FEIT; 26) Flight Element Integrated Test (FEIT); 27) Multi-Element Integrated Testing (MEIT); 28) Flight Test Driving Principles; and 29) Constellation s Integrated Flight Test Strategy Low Earth Orbit Servicing Capability.

77 FR 65582 - Notice of Determinations Regarding Eligibility To Apply for Worker Adjustment Assistance

Federal Register 2010, 2011, 2012, 2013, 2014

2012-10-29

.... Div., Back Office Customer Support, Primary Services & Inceed. 81,972 Pharmetrics, An IMS Health... Constellation Homebuilder Redmond, WA September 14, 2011. Systems, Fast Division, Constellation Software, Inc...

Zero, minimum and maximum relative radial acceleration for planar formation flight dynamics near triangular libration points in the Earth-Moon system

NASA Astrophysics Data System (ADS)

Salazar, F. J. T.; Masdemont, J. J.; Gómez, G.; Macau, E. E.; Winter, O. C.

2014-11-01

Assume a constellation of satellites is flying near a given nominal trajectory around L4 or L5 in the Earth-Moon system in such a way that there is some freedom in the selection of the geometry of the constellation. We are interested in avoiding large variations of the mutual distances between spacecraft. In this case, the existence of regions of zero and minimum relative radial acceleration with respect to the nominal trajectory will prevent from the expansion or contraction of the constellation. In the other case, the existence of regions of maximum relative radial acceleration with respect to the nominal trajectory will produce a larger expansion and contraction of the constellation. The goal of this paper is to study these regions in the scenario of the Circular Restricted Three Body Problem by means of a linearization of the equations of motion relative to the periodic orbits around L4 or L5. This study corresponds to a preliminar planar formation flight dynamics about triangular libration points in the Earth-Moon system. Additionally, the cost estimate to maintain the constellation in the regions of zero and minimum relative radial acceleration or keeping a rigid configuration is computed with the use of the residual acceleration concept. At the end, the results are compared with the dynamical behavior of the deviation of the constellation from a periodic orbit.

Mobile User Objective System (MUOS)

DTIC Science & Technology

2015-12-01

the current UHF Follow-On ( UFO ) constellation. MUOS includes the satellite constellation, a ground control and network management system, and a new...MUOS CAI. Each MUOS satellite carries a legacy payload similar to that flown on UFO -11. These legacy payloads will continue to support legacy...Antecedent Information The antecedent system to MUOS was the Ultra High Frequency (UHF) Follow-on ( UFO ) satellite communications program. Comparisons

Optimizing Spacecraft Placement for Liaison Constellations

NASA Technical Reports Server (NTRS)

Chow, C. Channing; Villac, Benjamin F.; Lo, Martin W.

2011-01-01

A navigation and communications network is proposed to support an anticipated need for infrastructure in the Earth-Moon system. Periodic orbits will host the constellations while a novel, autonomous navigation strategy will guide the spacecraft along their path strictly based on satellite-to-satellite telemetry. In particular, this paper investigates the second stage of a larger constellation optimization scheme for multi-spacecraft systems. That is, following an initial orbit down-selection process, this analysis provides insights into the ancillary problem of spacecraft placement. Two case studies are presented that consider configurations of up to four spacecraft for a halo orbit and a cycler trajectory.

Enhanced secure 4-D modulation space optical multi-carrier system based on joint constellation and Stokes vector scrambling.

PubMed

Liu, Bo; Zhang, Lijia; Xin, Xiangjun

2018-03-19

This paper proposes and demonstrates an enhanced secure 4-D modulation optical generalized filter bank multi-carrier (GFBMC) system based on joint constellation and Stokes vector scrambling. The constellation and Stokes vectors are scrambled by using different scrambling parameters. A multi-scroll Chua's circuit map is adopted as the chaotic model. Large secure key space can be obtained due to the multi-scroll attractors and independent operability of subcarriers. A 40.32Gb/s encrypted optical GFBMC signal with 128 parallel subcarriers is successfully demonstrated in the experiment. The results show good resistance against the illegal receiver and indicate a potential way for the future optical multi-carrier system.

Constellation Program Press Conference

NASA Image and Video Library

2006-06-04

NASA Administrator Michael Griffin, seated left, Scott Horowitz, NASA Associate Administrator for Exploration Systems and Jeff Hanley, Constellation Program Manager, right, are seen during a press conference outlining specific center responsibilities associated with the Constellation Program for robotic and human moon and Mars exploration, Monday, June 5, 2006, at NASA Headquarters in Washington. Dean Acosta, NASA Deputy Assistant Administrator and Press Secretary, far left, moderates the program. Photo Credit (NASA/Bill Ingalls)

Methodology and method and apparatus for signaling with capacity optimized constellations

NASA Technical Reports Server (NTRS)

Barsoum, Maged F. (Inventor); Jones, Christopher R. (Inventor)

2011-01-01

Communication systems having transmitter, includes a coder configured to receive user bits and output encoded bits at an expanded output encoded bit rate, a mapper configured to map encoded bits to symbols in a symbol constellation, a modulator configured to generate a signal for transmission via the communication channel using symbols generated by the mapper. In addition, the receiver includes a demodulator configured to demodulate the received signal via the communication channel, a demapper configured to estimate likelihoods from the demodulated signal, a decoder that is configured to estimate decoded bits from the likelihoods generated by the demapper. Furthermore, the symbol constellation is a capacity optimized geometrically spaced symbol constellation that provides a given capacity at a reduced signal-to-noise ratio compared to a signal constellation that maximizes d.sub.min.

MISTiC Winds, a Micro-Satellite Constellation Approach to High Resolution Observations of the Atmosphere Using Infrared Sounding and 3D Winds Measurements

NASA Technical Reports Server (NTRS)

Maschhoff, K. R.; Polizotti, J. J.; Aumann, H. H.; Susskind, J.

2016-01-01

MISTiC(TM) Winds is an approach to improve short-term weather forecasting based on a miniature high resolution, wide field, thermal emission spectrometry instrument that will provide global tropospheric vertical profiles of atmospheric temperature and humidity at high (3-4 km) horizontal and vertical ( 1 km) spatial resolution. MISTiCs extraordinarily small size, payload mass of less than 15 kg, and minimal cooling requirements can be accommodated aboard a 27U-class CubeSat or an ESPA-Class micro-satellite. Low fabrication and launch costs enable a LEO sunsynchronous sounding constellation that would collectively provide frequent IR vertical profiles and vertically resolved atmospheric motion vector wind observations in the troposphere. These observations are highly complementary to present and emerging environmental observing systems, and would provide a combination of high vertical and horizontal resolution not provided by any other environmental observing system currently in operation. The spectral measurements that would be provided by MISTiC Winds are similar to those of NASA's AIRS that was built by BAE Systems and operates aboard the AQUA satellite. These new observations, when assimilated into high resolution numerical weather models, would revolutionize short-term and severe weather forecasting, save lives, and support key economic decisions in the energy, air transport, and agriculture arenasat much lower cost than providing these observations from geostationary orbit. In addition, this observation capability would be a critical tool for the study of transport processes for water vapor, clouds, pollution, and aerosols. Key remaining technical risks are being reduced through laboratory and airborne testing under NASA's Instrument Incubator Program.

MISTiC Winds, a Micro-Satellite Constellation Approach to High Resolution Observations of the Atmosphere using Infrared Sounding and 3D Winds Measurements

NASA Astrophysics Data System (ADS)

Maschhoff, K. R.; Polizotti, J. J.; Susskind, J.; Aumann, H. H.

2015-12-01

MISTiCTM Winds is an approach to improve short-term weather forecasting based on a miniature high resolution, wide field, thermal emission spectrometry instrument that will provide global tropospheric vertical profiles of atmospheric temperature and humidity at high (3-4 km) horizontal and vertical ( 1 km) spatial resolution. MISTiC's extraordinarily small size, payload mass of less than 15 kg, and minimal cooling requirements can be accommodated aboard a 27U-class CubeSat or an ESPA-Class micro-satellite. Low fabrication and launch costs enable a LEO sun-synchronous sounding constellation that would collectively provide frequent IR vertical profiles and vertically resolved atmospheric motion vector wind observations in the troposphere. These observations are highly complementary to present and emerging environmental observing systems, and would provide a combination of high vertical and horizontal resolution not provided by any other environmental observing system currently in operation. The spectral measurements that would be provided by MISTiC Winds are similar to those of NASA's Atmospheric Infrared Sounder that was built by BAE Systems and operates aboard the AQUA satellite. These new observations, when assimilated into high resolution numerical weather models, would revolutionize short-term and severe weather forecasting, save lives, and support key economic decisions in the energy, air transport, and agriculture arenas-at much lower cost than providing these observations from geostationary orbit. In addition, this observation capability would be a critical tool for the study of transport processes for water vapor, clouds, pollution, and aerosols. Key technical risks are being reduced through laboratory and airborne testing under NASA's Instrument Incubator Program.

MISTiC Winds: A micro-satellite constellation approach to high resolution observations of the atmosphere using infrared sounding and 3D winds measurements

NASA Astrophysics Data System (ADS)

Maschhoff, K. R.; Polizotti, J. J.; Aumann, H. H.; Susskind, J.

2016-09-01

MISTiCTM Winds is an approach to improve short-term weather forecasting based on a miniature high resolution, wide field, thermal emission spectrometry instrument that will provide global tropospheric vertical profiles of atmospheric temperature and humidity at high (3-4 km) horizontal and vertical ( 1 km) spatial resolution. MISTiC's extraordinarily small size, payload mass of less than 15 kg, and minimal cooling requirements can be accommodated aboard a 27U-class CubeSat or an ESPA-Class micro-satellite. Low fabrication and launch costs enable a LEO sunsynchronous sounding constellation that would collectively provide frequent IR vertical profiles and vertically resolved atmospheric motion vector wind observations in the troposphere. These observations are highly complementary to present and emerging environmental observing systems, and would provide a combination of high vertical and horizontal resolution not provided by any other environmental observing system currently in operation. The spectral measurements that would be provided by MISTiC Winds are similar to those of NASA's AIRS that was built by BAE Systems and operates aboard the AQUA satellite. These new observations, when assimilated into high resolution numerical weather models, would revolutionize short-term and severe weather forecasting, save lives, and support key economic decisions in the energy, air transport, and agriculture arenas-at much lower cost than providing these observations from geostationary orbit. In addition, this observation capability would be a critical tool for the study of transport processes for water vapor, clouds, pollution, and aerosols. Key remaining technical risks are being reduced through laboratory and airborne testing under NASA's Instrument Incubator Program.

Mistic winds, a microsatellite constellation approach to high-resolution observations of the atmosphere using infrared sounding and 3d winds measurements

NASA Astrophysics Data System (ADS)

Maschhoff, K. R.; Polizotti, J. J.; Aumann, H. H.; Susskind, J.

2016-10-01

MISTiC Winds is an approach to improve short-term weather forecasting based on a miniature high resolution, wide field, thermal emission spectrometry instrument that will provide global tropospheric vertical profiles of atmospheric temperature and humidity at high (3-4 km) horizontal and vertical ( 1 km) spatial resolution. MISTiC's extraordinarily small size, payload mass of less than 15 kg, and minimal cooling requirements can be accommodated aboard a 27U-class CubeSat or an ESPA-Class micro-satellite. Low fabrication and launch costs enable a LEO sunsynchronous sounding constellation that would collectively provide frequent IR vertical profiles and vertically resolved atmospheric motion vector wind observations in the troposphere. These observations are highly complementary to present and emerging environmental observing systems, and would provide a combination of high vertical and horizontal resolution not provided by any other environmental observing system currently in operation. The spectral measurements that would be provided by MISTiC Winds are similar to those of NASA's AIRS that was built by BAE Systems and operates aboard the AQUA satellite. These new observations, when assimilated into high resolution numerical weather models, would revolutionize short-term and severe weather forecasting, save lives, and support key economic decisions in the energy, air transport, and agriculture arenas-at much lower cost than providing these observations from geostationary orbit. In addition, this observation capability would be a critical tool for the study of transport processes for water vapor, clouds, pollution, and aerosols. Key remaining technical risks are being reduced through laboratory and airborne testing under NASA's Instrument Incubator Program.

Science Opportunities Enabled by NASA's Constellation System: Interim Report

NASA Astrophysics Data System (ADS)

Committee On Science Opportunities Enabled By Nasa'S Constellation System, National Research Council

To begin implementation of the Vision for Space Exploration (recently renamed "United States Space Exploration Policy"), NASA has begun development of new launch vehicles and a human-carrying spacecraft that are collectively called the Constellation System. In November 2007, NASA asked the NRC to evaluate the potential for the Constellation System to enable new space science opportunities. For this interim report, 11 existing "Vision Mission" studies of advanced space science mission concepts inspired by earlier NASA forward-looking studies were evaluated. The focus was to assess the concepts and group them into two categories: more-deserving or less deserving of future study. This report presents a description of the Constellation System and its opportunities for enabling new space science opportunities, and a systematic analysis of the 11 Vision Mission studies. For the final report, the NRC issued a request for information to the relevant communities to obtain ideas for other mission concepts that will be assessed by the study committee, and several issues addressed only briefly in the interim report will be explored more fully.

Regional positioning using a low Earth orbit satellite constellation

NASA Astrophysics Data System (ADS)

Shtark, Tomer; Gurfil, Pini

2018-02-01

Global and regional satellite navigation systems are constellations orbiting the Earth and transmitting radio signals for determining position and velocity of users around the globe. The state-of-the-art navigation satellite systems are located in medium Earth orbits and geosynchronous Earth orbits and are characterized by high launching, building and maintenance costs. For applications that require only regional coverage, the continuous and global coverage that existing systems provide may be unnecessary. Thus, a nano-satellites-based regional navigation satellite system in Low Earth Orbit (LEO), with significantly reduced launching, building and maintenance costs, can be considered. Thus, this paper is aimed at developing a LEO constellation optimization and design method, using genetic algorithms and gradient-based optimization. The preliminary results of this study include 268 LEO constellations, aimed at regional navigation in an approximately 1000 km × 1000 km area centered at the geographic coordinates [30, 30] degrees. The constellations performance is examined using simulations, and the figures of merit include total coverage time, revisit time, and geometric dilution of precision (GDOP) percentiles. The GDOP is a quantity that determines the positioning solution accuracy and solely depends on the spatial geometry of the satellites. Whereas the optimization method takes into account only the Earth's second zonal harmonic coefficient, the simulations include the Earth's gravitational field with zonal and tesseral harmonics up to degree 10 and order 10, Solar radiation pressure, drag, and the lunisolar gravitational perturbation.

Enabling Global Observations of Clouds and Precipitation on Fine Spatio-Temporal Scales from CubeSat Constellations: Temporal Experiment for Storms and Tropical Systems Technology Demonstration (TEMPEST-D)

NASA Astrophysics Data System (ADS)

Reising, S. C.; Todd, G.; Padmanabhan, S.; Lim, B.; Heneghan, C.; Kummerow, C.; Chandra, C. V.; Berg, W. K.; Brown, S. T.; Pallas, M.; Radhakrishnan, C.

2017-12-01

The Temporal Experiment for Storms and Tropical Systems (TEMPEST) mission concept consists of a constellation of 5 identical 6U-Class satellites observing storms at 5 millimeter-wave frequencies with 5-10 minute temporal sampling to observe the time evolution of clouds and their transition to precipitation. Such a small satellite mission would enable the first global measurements of clouds and precipitation on the time scale of tens of minutes and the corresponding spatial scale of a few km. TEMPEST is designed to improve the understanding of cloud processes by providing critical information on temporal signatures of precipitation and helping to constrain one of the largest sources of uncertainty in cloud models. TEMPEST millimeter-wave radiometers are able to perform remote observations of the cloud interior to observe microphysical changes as the cloud begins to precipitate or ice accumulates inside the storm. The TEMPEST technology demonstration (TEMPEST-D) mission is in progress to raise the TRL of the instrument and spacecraft systems from 6 to 9 as well as to demonstrate radiometer measurement and differential drag capabilities required to deploy a constellation of 6U-Class satellites in a single orbital plane. The TEMPEST-D millimeter-wave radiometer instrument provides observations at 89, 165, 176, 180 and 182 GHz using a single compact instrument designed for 6U-Class satellites. The direct-detection topology of the radiometer receiver substantially reduces both its power consumption and design complexity compared to heterodyne receivers. The TEMPEST-D instrument performs precise, end-to-end calibration using a cross-track scanning reflector to view an ambient blackbody calibration target and cosmic microwave background every scan period. The TEMPEST-D radiometer instrument has been fabricated and successfully tested under environmental conditions (vibration, thermal cycling and vacuum) expected in low-Earth orbit. TEMPEST-D began in Aug. 2015, with a rapid 2.5-year development to deliver a complete spacecraft with integrated payload by Feb. 2018. TEMPEST-D has been manifested by NASA CSLI planned for launch on ELaNa-23 on Cygnus Antares II to the ISS in Mar. 2018. The TEMPEST-D satellite is expected to be deployed into a 400-km orbit at 51.6° inclination a few months after arrival at ISS.

First Time-Resolved Observations of Precipitation Structure and Storm Intensity with a Constellation of Smallsats (TROPICS) Mission Applications Workshop Summary Report

NASA Technical Reports Server (NTRS)

Zavodsky, B.; Dunion, J.; Blackwell, W.; Braun, S.; Velden, C.; Brennan, M.; Adler, R.

2017-01-01

The National Aeronautics and Space Administration (NASA) Time-Resolved Observations of Precipitation structure and storm Intensity with a Constellation of SmallSats (TROPICS) mission is a constellation of state-of-the-science observing platforms that will measure temperature and humidity soundings and precipitation with spatial resolution comparable to current operational passive microwave sounders but with unprecedented temporal resolution. TROPICS is a cost-capped ($30 million) Venture-class mission funded by the NASA Earth Science Division (ESD) and led by principal investigator Dr. William Blackwell from the Massachusetts Institute of Technology Lincoln Laboratory (MIT LL). The mission is comprised of a constellation of six, three-unit (3U) Cube-Sats (approximately 10 by 10 by 34 centimeters), each hosting a 12-channel passive microwave spectrometer based on the Micro-sized Microwave Atmospheric Satellite 2 (MicroMAS-2) developed at MIT LL. TROPICS will provide imagery at frequencies near 91 and 205 gigahertz, temperature sounding near 118 gigahertz, and moisture sounding near 183 gigahertz. Spatial resolution at nadir will be around 27 kilometers for temperature and 17 kilometers for moisture and precipitation with a swath width of approximately 2,000 kilometers. Both the spatial resolution and swath width are similar to the Advanced Technology Microwave Sounder (ATMS) that is being flown as part of the Suomi National Polar-Orbiting Partnership and will fly starting in 2017 on the National Oceanic and Atmospheric Administration (NOAA) Joint Polar Satellite System (JPSS). In addition, TROPICS meets many of the requirements outlined in the 2007 Decadal Survey for the Precision and All-Weather Temperature and Humidity mission, which was originally envisioned as a microwave instrument in geostationary orbit. TROPICS enables temporal resolution similar to geostationary orbit but at a much lower cost, demonstrating a technology that could impact the design of future Earth-observing missions. The satellites for the TROPICS mission are slated for delivery to NASA in 2019 for launches planned no earlier than 2020. The primary mission objective of TROPICS is to relate temperature, humidity, and precipitation structure to the evolution of tropical cyclone (TC) intensity.

NASA CYGNSS Mission Applications Workshop

NASA Technical Reports Server (NTRS)

Amin, Aimee V. (Compiler); Murray, John J. (Editor); Stough, Timothy M. (Editor); Molthan, Andrew (Editor)

2015-01-01

NASA's Cyclone Global Navigation Satellite System, (CYGNSS), mission is a constellation of eight microsatellites that will measure surface winds in and near the inner cores of hurricanes, including regions beneath the eyewall and intense inner rainbands that could not previously be measured from space. The CYGNSS-measured wind fields, when combined with precipitation fields (e.g., produced by the Global Precipitation Measurement [GPM] core satellite and its constellation of precipitation imagers), will provide coupled observations of moist atmospheric thermodynamics and ocean surface response, enabling new insights into hurricane inner core dynamics and energetics. The outcomes of this workshop, which are detailed in this report, comprise two primary elements: (1) A report of workshop proceedings, and; (2) Detailed Applications Traceability Matrices with requirements and operational considerations to serve broadly for development of value-added tools, applications, and products.

Small Satellite Constellations for Geospace Sciences

NASA Astrophysics Data System (ADS)

Spence, H. E.

2016-12-01

The recent National Academy of Sciences Solar and Space Physics Decadal Survey (DS) identified community-consensus science priorities for the decade spanning 2013 - 2022. In this talk, we discuss the ways by which small satellite constellations are already and may soon accelerate progress toward achieving many of these science targets. The DS outlined four overarching science goals: (1) determine the origins of the Sun's activity and predict the variations in the space environment; (2) determine the dynamics and coupling of Earth's magnetosphere, ionosphere, and atmosphere and their response to solar and terrestrial inputs; (3) determine the interaction of the Sun with the solar system and the interstellar medium; and, (4) discover and characterize fundamental processes that occur both within the heliosphere and throughout the universe. These DS science goals provide the context for key science challenges in the three connected parts of the system that encompass all of solar and space physics, herein referred to as geospace: the Sun and heliosphere; the coupled solar wind-magnetosphere system; and, the coupled atmosphere-ionosphere-magnetosphere system. The DS further presented the role that small satellites play in resolving many of these science challenges, with a particular emphasis on the role that constellations of small satellites will play. While once considered by many as being "futuristic" or even "unrealizable", constellations of small satellites are already making important contributions to geospace science and with the promise for more to come. Using the DS as a guidepost, in this presentation, we outline representative small satellite constellation missions alread underway, some in development, and others notionally proposed over the next several years that employ small satellite constellations to tackle large science imperatives. Finally, we give examples of key small satellite technologies in development that will potentially enable great scientific return with comparatively low investments in small satellite missions.

Constellation Program Life-cycle Cost Analysis Model (LCAM)

NASA Technical Reports Server (NTRS)

Prince, Andy; Rose, Heidi; Wood, James

2008-01-01

The Constellation Program (CxP) is NASA's effort to replace the Space Shuttle, return humans to the moon, and prepare for a human mission to Mars. The major elements of the Constellation Lunar sortie design reference mission architecture are shown. Unlike the Apollo Program of the 1960's, affordability is a major concern of United States policy makers and NASA management. To measure Constellation affordability, a total ownership cost life-cycle parametric cost estimating capability is required. This capability is being developed by the Constellation Systems Engineering and Integration (SE&I) Directorate, and is called the Lifecycle Cost Analysis Model (LCAM). The requirements for LCAM are based on the need to have a parametric estimating capability in order to do top-level program analysis, evaluate design alternatives, and explore options for future systems. By estimating the total cost of ownership within the context of the planned Constellation budget, LCAM can provide Program and NASA management with the cost data necessary to identify the most affordable alternatives. LCAM is also a key component of the Integrated Program Model (IPM), an SE&I developed capability that combines parametric sizing tools with cost, schedule, and risk models to perform program analysis. LCAM is used in the generation of cost estimates for system level trades and analyses. It draws upon the legacy of previous architecture level cost models, such as the Exploration Systems Mission Directorate (ESMD) Architecture Cost Model (ARCOM) developed for Simulation Based Acquisition (SBA), and ATLAS. LCAM is used to support requirements and design trade studies by calculating changes in cost relative to a baseline option cost. Estimated costs are generally low fidelity to accommodate available input data and available cost estimating relationships (CERs). LCAM is capable of interfacing with the Integrated Program Model to provide the cost estimating capability for that suite of tools.

Optimizing space constellations for mobile satellite systems

NASA Technical Reports Server (NTRS)

Roussel, T.; Taisant, J.-P.

1993-01-01

Designing a mobile satellite system entails many complex trade-offs between a great number of parameters including: capacity, complexity of the payload, constellation geometry, number of satellites, quality of coverage, etc. This paper aims at defining a methodology which tries to split the variables to give rapidly some first results. The major input considered is the traffic assumption which would be offered by the system. A first key step is the choice of the best Rider or Walker constellation geometries - with different numbers of satellites - to insure a good quality of coverage over a selected service area. Another aspect to be addressed is the possible altitude location of the constellation, since it is limited by many constraints. The altitude ranges that seem appropriate considering the spatial environment, the launch and orbit keeping policy and the feasibility of the antenna allowing sufficient frequency reuse are briefly analyzed. To support these first considerations, some 'reference constellations' with similar coverage quality are chosen. The in-orbit capacity needed to support the assumed traffic is computed versus altitude. Finally, the exact number of satellite is determined. It comes as an optimum between a small number of satellites offering a high (and costly) power margin in bad propagation situation and a great number of less powerful satellites granting the same quality of service.

Optimizing space constellations for mobile satellite systems

NASA Astrophysics Data System (ADS)

Roussel, T.; Taisant, J.-P.

Designing a mobile satellite system entails many complex trade-offs between a great number of parameters including: capacity, complexity of the payload, constellation geometry, number of satellites, quality of coverage, etc. This paper aims at defining a methodology which tries to split the variables to give rapidly some first results. The major input considered is the traffic assumption which would be offered by the system. A first key step is the choice of the best Rider or Walker constellation geometries - with different numbers of satellites - to insure a good quality of coverage over a selected service area. Another aspect to be addressed is the possible altitude location of the constellation, since it is limited by many constraints. The altitude ranges that seem appropriate considering the spatial environment, the launch and orbit keeping policy and the feasibility of the antenna allowing sufficient frequency reuse are briefly analyzed. To support these first considerations, some 'reference constellations' with similar coverage quality are chosen. The in-orbit capacity needed to support the assumed traffic is computed versus altitude. Finally, the exact number of satellite is determined. It comes as an optimum between a small number of satellites offering a high (and costly) power margin in bad propagation situation and a great number of less powerful satellites granting the same quality of service.

The Science Goals of the Constellation-X Mission

NASA Technical Reports Server (NTRS)

White, Nicholas E.; Tananbaum, Harvey; Weaver, Kimberly; Petre, Robert; Bookbinder, Jay

2004-01-01

The Constellation-X mission will address the questions: "What happens to matter close to a black hole?" and "What is Dark Energy?" These questions are central to the NASA Beyond Einstein Program, where Constellation-X plays a central role. The mission will address these questions by using high throughput X-ray spectroscopy to observe the effects of strong gravity close to the event horizon of black holes, and to observe the formation and evolution of clusters of galaxies in order to precisely determine Cosmological parameters. To achieve these primary science goals requires a factor of 25-100 increase in sensitivity for high resolution spectroscopy. The mission will also perform routine high- resolution X-ray spectroscopy of faint and extended X-ray source populations. This will provide diagnostic information such as density, elemental abundances, velocity, and ionization state for a wide range of astrophysical problems. This has enormous potential for the discovery of new unexpected phenomena. The Constellation-X mission is a high priority in the National Academy of Sciences McKee-Taylor Astronomy and Astrophysics Survey of new Astrophysics Facilities for the first decade of the 21st century.

Mobile User Objective System (MUOS)

DTIC Science & Technology

2013-12-01

system capacity of the current UHF Follow-On ( UFO ) constellation. MUOS includes the satellite constellation, a ground control and network management...terminals able to support the MUOS CAI. Each MUOS satellite carries a legacy payload similar to that flown on UFO -11. These legacy payloads will...Antecedent Information: The antecedent system to MUOS was the Ultra High Frequency (UHF) Follow-on ( UFO ) satellite communications program. Comparisons of O

Long Term Measurement of the Earth's Radiation Budget using a constellation of Broadband Radiometers hosted on Iridium NEXT

NASA Astrophysics Data System (ADS)

Gupta, Om Prakash; Thoma, Donald; Chaloner, Chris; Russell, Jacqueline; Simpson, Bill; Spilling, David; Morris, Nigel; Caldwell, Martin; Oneill, Alan

The WMO called for "bringing new missions to operational status" and that "ERB should be measured through a constellation of sensors". A unique opportu-nity exists to host a set of Earth Radiation Budget (ERB) sensors on the Iridium NEXT (NEXT) LEO constellation in a cost effective manner that can deliver these requirements. The NEXT constellation, with 66 interconnected satellites in 6 near polar orbiting planes, provides a unique platform for hosting a variety of Earth observation missions including ERB. Launches are planned to begin in 2014 through 2016. The ERB both drives and responds to global climate and monitoring it can provide much insight into the climate system and how it might be changing. A climate quality measurement of the ERB requires high absolute accuracy and excellent stability and a long-term (decades) data record in order to inform the debate about global warming. Measurement of the ERB in terms of the broadband reflected solar (0.3 to 4 µm) and emitted thermal (4 to 200 µm) components have been identified as high priority by the WMO for climate observations. High temporal resolution is the key advantage offered by the NEXT platform and can provide a great step forward in accurately monitoring the energy balance of the planet. The sensor we propose will consist of a broad band instrument and associated imager for scene identification and cloud classification. There is the chance to place two such sensors in each of six different orbital planes this will improve the product refresh time from currently 12 hours to 3 hours. The increased temporal resolution will allow direct measure-ment of the changes to the broadband radiances that result from rapidly varying components of the climate such as cloud and aerosol, and avoid the need of relying on narrow band sensors to infer such changes. Considering that the prediction of cloud response to climate change is still a major source of uncertainty; improved measurement of the cloud effect and possible changes in this quantity are of particular interest. This proposed configuration of twelve ERB sensors on NEXT has been analyzed in a detailed study by this team and demonstrated to have compatibility with proposed NEXT satellites. This study has also demonstrated the following: 1. Full globe coverage, including the poles, and 3 hourly temporal resolution even at the equator 2. Spatial coverage with a swath of each sensor of 1000 km and resolution of 10 km at nadir 3. LEO orbits which are not sun-synchronous so aliasing effects, which are always a concern with single sensors in sun-synchronous orbits, are no longer of concern 4. Twelve sensors in orbit simultaneously, with frequent near-coincidences at high latitudes, so cross-calibration will become a normal part of the system operation. Cross-calibration will also be possible against current sensors such as CERES in LEO and GERB in GEO and offers the possibly of combined products with the sensors. 5. The data stream will be in real-time via the NEXT communications network 6. System robustness is assured since loss of a sensor or satellite is not mission critical 7. Low risk and short lead times because heritage sensors are to be deployed 8. Low chance of launch delays or mission creep, since timing is crucial to the Iridium's business 9. Planned long constellation design life reduces long term cost and continuity problems 10. Near-certain continuity missions as follow-on constellations are part of the host's business plans 11. A move to truly operational observations using real, rather than virtual, constellation 12. A significantly lower cost alternative to traditional methods for collecting this data.

NASA's GMAO Atmospheric Motion Vectors Simulator: Description and Application to the MISTiC Winds Concept

NASA Technical Reports Server (NTRS)

Carvalho, David; McCarty, Will; Errico, Ron; Prive, Nikki

2018-01-01

An atmospheric wind vectors (AMVs) simulator was developed by NASA's GMAO to simulate observations from future satellite constellation concepts. The synthetic AMVs can then be used in OSSEs to estimate and quantify the potential added value of new observations to the present Earth observing system and, ultimately, the expected impact on the current weather forecasting skill. The GMAO AMV simulator is a tunable and flexible computer code that is able to simulate AMVs expected to be derived from different instruments and satellite orbit configurations. As a case study and example of the usefulness of this tool, the GMAO AMV simulator was used to simulate AMVs envisioned to be provided by the MISTiC Winds, a NASA mission concept consisting of a constellation of satellites equipped with infrared spectral midwave spectrometers, expected to provide high spatial and temporal resolution temperature and humidity soundings of the troposphere that can be used to derive AMVs from the tracking of clouds and water vapor features. The GMAO AMV simulator identifies trackable clouds and water vapor features in the G5NR and employs a probabilistic function to draw a subset of the identified trackable features. Before the simulator is applied to the MISTiC Winds concept, the simulator was calibrated to yield realistic observations counts and spatial distributions and validated considering as a proxy instrument to the MISTiC Winds the Himawari-8 Advanced Imager (AHI). The simulated AHI AMVs showed a close match with the real AHI AMVs in terms of observation counts and spatial distributions, showing that the GMAO AMVs simulator synthesizes AMVs observations with enough quality and realism to produce a response from the DAS equivalent to the one produced with real observations. When applied to the MISTiC Winds scanning points, it can be expected that the MISTiC Winds will be able to collect approximately 60,000 wind observations every 6 hours, if considering a constellation composed of 12 satellites (4 orbital planes). In addition, one of the main expected impacts of the MISTiC Winds concept is the ability to derive water vapor feature tracking AMVs below 500-400 hPa, an unique feature among the water vapor AMVs derived from the current Earth observing system.

Mapping 3D plasma structure in the solar wind with the L1 constellation: joint observations from Wind, ACE, DSCOVR, and SoHO

NASA Astrophysics Data System (ADS)

Stevens, M. L.; Kasper, J. C.; Case, A. W.; Korreck, K. E.; Szabo, A.; Biesecker, D. A.; Prchlik, J.

2017-12-01

At this moment in time, four observatories with similar instrumentation- Wind, ACE, DSCOVR, and SoHO- are stationed directly upstream of the Earth and making continuous observations. They are separated by drift-time baselines of seconds to minutes, timescales on which MHD instabilities in the solar wind are known to grow and evolve, and spatial baselines of tens to 200 earth radii, length scales relevant to the Earth's magnetosphere. By comparing measurements of matched solar wind structures from the four vantage points, the form of structures and associated dynamics on these scales is illuminated. Our targets include shocks and MHD discontinuities, stream fronts, locii of reconnection and exhaust flow boundary layers, plasmoids, and solitary structures born of nonlinear instability. We use the tetrahedral quality factors and other conventions adopted for Cluster to identify periods where the WADS constellation is suitably non-degenerate and arranged in such a way as to enable specific types of spatial, temporal, or spatiotemporal inferences. We present here an overview of the geometries accessible to the L1 constellation and timing-based and plasma-based observations of solar wind structures from 2016-17. We discuss the unique potential of the constellation approach for space physics and space weather forecasting at 1 AU.

Hot spots of multivariate extreme anomalies in Earth observations

NASA Astrophysics Data System (ADS)

Flach, M.; Sippel, S.; Bodesheim, P.; Brenning, A.; Denzler, J.; Gans, F.; Guanche, Y.; Reichstein, M.; Rodner, E.; Mahecha, M. D.

2016-12-01

Anomalies in Earth observations might indicate data quality issues, extremes or the change of underlying processes within a highly multivariate system. Thus, considering the multivariate constellation of variables for extreme detection yields crucial additional information over conventional univariate approaches. We highlight areas in which multivariate extreme anomalies are more likely to occur, i.e. hot spots of extremes in global atmospheric Earth observations that impact the Biosphere. In addition, we present the year of the most unusual multivariate extreme between 2001 and 2013 and show that these coincide with well known high impact extremes. Technically speaking, we account for multivariate extremes by using three sophisticated algorithms adapted from computer science applications. Namely an ensemble of the k-nearest neighbours mean distance, a kernel density estimation and an approach based on recurrences is used. However, the impact of atmosphere extremes on the Biosphere might largely depend on what is considered to be normal, i.e. the shape of the mean seasonal cycle and its inter-annual variability. We identify regions with similar mean seasonality by means of dimensionality reduction in order to estimate in each region both the `normal' variance and robust thresholds for detecting the extremes. In addition, we account for challenges like heteroscedasticity in Northern latitudes. Apart from hot spot areas, those anomalies in the atmosphere time series are of particular interest, which can only be detected by a multivariate approach but not by a simple univariate approach. Such an anomalous constellation of atmosphere variables is of interest if it impacts the Biosphere. The multivariate constellation of such an anomalous part of a time series is shown in one case study indicating that multivariate anomaly detection can provide novel insights into Earth observations.

A Challenging Trio in Space 'Routine' Operations of the Swarm Satellite Constellation

NASA Astrophysics Data System (ADS)

Diekmann, Frank-Jurgen; Clerigo, Ignacio; Albini, Giuseppe; Maleville, Laurent; Neto, Alessandro; Patterson, David; Nino, Ana Piris; Sieg, Detlef

2016-08-01

Swarm is the first ESA Earth Observation Mission with three satellites flying in a semi-controlled constellation. The trio is operated from ESA's satellite control centre ESOC in Darmstadt, Germany. The Swarm Flight Operations Segment consists of the typical elements of a satellite control system at ESOC, but had to be carefully tailored for this innovative mission. The main challenge was the multi-satellite system of Swarm, which necessitated the development of a Mission Control System with a multi-domain functionality, both in hardware and software and covering real-time and backup domains. This was driven by the need for extreme flexibility for constellation operations and parallel activities.The three months of commissioning in 2014 were characterized by a very tight and dynamically changing schedule of activities. All operational issues could be solved during that time, including the challenging orbit acquisition phase to achieve the final constellation.Although the formal spacecraft commissioning phase was concluded in spring 2014, the investigations for some payload instruments continue even today. The Electrical Field Instruments are for instance still being tested in order to characterize and improve science data quality. Various test phases also became necessary for the Accelerometers on the Swarm satellites. In order to improve the performance of the GPS Receivers for better scientific exploitation and to minimize the failures due to loss of synchronization, a number of parameter changes were commanded via on-board patches.Finally, to minimize the impact on operations, a new strategy had to be implemented to handle single/multi bit errors in the on-board mass Memories, defining when to ignore and when to restore the memory via a re-initialisation.The poster presentation summarizes the Swarm specific ground segment elements of the FOS and explains some of the extended payload commissioning operations, turning Swarm into a most demanding and challenging mission for the Flight Control Team at ESOC.

Classical and modern control strategies for the deployment, reconfiguration, and station-keeping of the National Aeronautics and Space Administration (NASA) Benchmark Tetrahedron Constellation

NASA Astrophysics Data System (ADS)

Capo-Lugo, Pedro A.

Formation flying consists of multiple spacecraft orbiting in a required configuration about a planet or through Space. The National Aeronautics and Space Administration (NASA) Benchmark Tetrahedron Constellation is one of the proposed constellations to be launched in the year 2009 and provides the motivation for this investigation. The problem that will be researched here consists of three stages. The first stage contains the deployment of the satellites; the second stage is the reconfiguration process to transfer the satellites through different specific sizes of the NASA benchmark problem; and, the third stage is the station-keeping procedure for the tetrahedron constellation. Every stage contains different control schemes and transfer procedures to obtain/maintain the proposed tetrahedron constellation. In the first stage, the deployment procedure will depend on a combination of two techniques in which impulsive maneuvers and a digital controller are used to deploy the satellites and to maintain the tetrahedron constellation at the following apogee point. The second stage that corresponds to the reconfiguration procedure shows a different control scheme in which the intelligent control systems are implemented to perform this procedure. In this research work, intelligent systems will eliminate the use of complex mathematical models and will reduce the computational time to perform different maneuvers. Finally, the station-keeping process, which is the third stage of this research problem, will be implemented with a two-level hierarchical control scheme to maintain the separation distance constraints of the NASA Benchmark Tetrahedron Constellation. For this station-keeping procedure, the system of equations defining the dynamics of a pair of satellites is transformed to take in account the perturbation due to the oblateness of the Earth and the disturbances due to solar pressure. The control procedures used in this research will be transformed from a continuous control system to a digital control system which will simplify the implementation into the computer onboard the satellite. In addition, this research will show an introductory chapter on attitude dynamics that can be used to maintain the orientation of the satellites, and an adaptive intelligent control scheme will be proposed to maintain the desired orientation of the spacecraft. In conclusion, a solution for the dynamics of the NASA Benchmark Tetrahedron Constellation will be presented in this research work. The main contribution of this work is the use of discrete control schemes, impulsive maneuvers, and intelligent control schemes that can be used to reduce the computational time in which these control schemes can be easily implemented in the computer onboard the satellite. These contributions are explained through the deployment, reconfiguration, and station-keeping process of the proposed NASA Benchmark Tetrahedron Constellation.

Design and Analysis of on-Orbit Servicing Architectures for the Global Positioning System Constellation

DTIC Science & Technology

1999-03-01

expressed in this thesis are those of the author and do not reflect the official policy or position of the Department of Defense or the U.S...a satellite constellation through a policy of launching a new satellite at the first on-orbit failure. Increasing satellite design life is a common...alternatives consisted of the current constellation with the addition of various servicing architectures. We assumed no radical shift in GPS management policy

Complementarity of ResourceSat-1 AWiFS and Landsat TM/ETM+ sensors

USGS Publications Warehouse

Goward, S.N.; Chander, G.; Pagnutti, M.; Marx, A.; Ryan, R.; Thomas, N.; Tetrault, R.

2012-01-01

Considerable interest has been given to forming an international collaboration to develop a virtual moderate spatial resolution land observation constellation through aggregation of data sets from comparable national observatories such as the US Landsat, the Indian ResourceSat and related systems. This study explores the complementarity of India's ResourceSat-1 Advanced Wide Field Sensor (AWiFS) with the Landsat 5 Thematic Mapper (TM) and Landsat 7 Enhanced Thematic Mapper Plus (ETM+). The analysis focuses on the comparative radiometry, geometry, and spectral properties of the two sensors. Two applied assessments of these data are also explored to examine the strengths and limitations of these alternate sources of moderate resolution land imagery with specific application domains. There are significant technical differences in these imaging systems including spectral band response, pixel dimensions, swath width, and radiometric resolution which produce differences in observation data sets. None of these differences was found to strongly limit comparable analyses in agricultural and forestry applications. Overall, we found that the AWiFS and Landsat TM/ETM+ imagery are comparable and in some ways complementary, particularly with respect to temporal repeat frequency. We have found that there are limits to our understanding of the AWiFS performance, for example, multi-camera design and stability of radiometric calibration over time, that leave some uncertainty that has been better addressed for Landsat through the Image Assessment System and related cross-sensor calibration studies. Such work still needs to be undertaken for AWiFS and similar observatories that may play roles in the Global Earth Observation System of Systems Land Surface Imaging Constellation.

Observational Constraints on Cloud Feedbacks: The Role of Active Satellite Sensors

NASA Astrophysics Data System (ADS)

Winker, David; Chepfer, Helene; Noel, Vincent; Cai, Xia

2017-11-01

Cloud profiling from active lidar and radar in the A-train satellite constellation has significantly advanced our understanding of clouds and their role in the climate system. Nevertheless, the response of clouds to a warming climate remains one of the largest uncertainties in predicting climate change and for the development of adaptions to change. Both observation of long-term changes and observational constraints on the processes responsible for those changes are necessary. We review recent progress in our understanding of the cloud feedback problem. Capabilities and advantages of active sensors for observing clouds are discussed, along with the importance of active sensors for deriving constraints on cloud feedbacks as an essential component of a global climate observing system.

NASA Project Constellation Systems Engineering Approach

NASA Technical Reports Server (NTRS)

Dumbacher, Daniel L.

2005-01-01

NASA's Office of Exploration Systems (OExS) is organized to empower the Vision for Space Exploration with transportation systems that result in achievable, affordable, and sustainable human and robotic journeys to the Moon, Mars, and beyond. In the process of delivering these capabilities, the systems engineering function is key to implementing policies, managing mission requirements, and ensuring technical integration and verification of hardware and support systems in a timely, cost-effective manner. The OExS Development Programs Division includes three main areas: (1) human and robotic technology, (2) Project Prometheus for nuclear propulsion development, and (3) Constellation Systems for space transportation systems development, including a Crew Exploration Vehicle (CEV). Constellation Systems include Earth-to-orbit, in-space, and surface transportation systems; maintenance and science instrumentation; and robotic investigators and assistants. In parallel with development of the CEV, robotic explorers will serve as trailblazers to reduce the risk and costs of future human operations on the Moon, as well as missions to other destinations, including Mars. Additional information is included in the original extended abstract.

A BRITE view on δ Scuti and γ Doradus stars

NASA Astrophysics Data System (ADS)

Zwintz, K.

2017-09-01

BRITE-Constellation has obtained data for a few δ; Scuti and γ Doradus type stars. A short overview of the pulsational content found in five stars - β Cassiopeiae, ɛ Cephei, M Velorum, β Pictoris and QW Puppis - is given and the potential of BRITE-Constellation observations of δ Scuti and γ Doradus pulsators is discussed.

Surface Landing Site Weather Analysis for Constellation Program

NASA Technical Reports Server (NTRS)

Altino, Karen M.; Burns, K. Lee

2008-01-01

Weather information is an important asset for NASA's Constellation Program in developing the next generation space transportation system to fly to the International Space Station, the Moon and, eventually, to Mars. Weather conditions can affect vehicle safety and performance during multiple mission phases ranging from pre-launch ground processing to landing and recovery operations, including all potential abort scenarios. Meteorological analysis is an important contributor, not only to the development and verification of system design requirements but also to mission planning and active ground operations. Of particular interest are the surface atmospheric conditions at both nominal and abort landing sites for the manned Orion capsule. Weather parameters such as wind, rain, and fog all play critical roles in the safe landing of the vehicle and subsequent crew and vehicle recovery. The Marshall Space Flight Center Natural Environments Branch has been tasked by the Constellation Program with defining the natural environments at potential landing zones. Climatological time series of operational surface weather observations are used to calculate probabilities of occurrence of various sets of hypothetical vehicle constraint thresholds, Data are available for numerous geographical locations such that statistical analysis can be performed for single sites as well as multiple-site network configurations. Results provide statistical descriptions of how often certain weather conditions are observed at the site(s) and the percentage that specified criteria thresholds are matched or exceeded. Outputs are tabulated by month and hour of day to show both seasonal and diurnal variation. This paper will describe the methodology used for data collection and quality control, detail the types of analyses performed, and provide a sample of the results that can be obtained,

Initial Assessment of Cyclone Global Navigation Satellite System (CYGNSS) Observations

NASA Astrophysics Data System (ADS)

McKague, D. S.; Ruf, C. S.

2017-12-01

The NASA Cyclone Global Navigation Satellite System (CYNSS) mission provides high temporal resolution observations of cyclones from a constellation of eight low-Earth orbiting satellites. Using the relatively new technique of Global Navigation Satellite System reflectometry (GNSS-R), all-weather observations are possible, penetrating even deep convection within hurricane eye walls. The compact nature of the GNSS-R receivers permits the use of small satellites, which in turn enables the launch of a constellation of satellites from a single launch vehicle. Launched in December of 2016, the eight CYGNSS satellites provide 25 km resolution observations of mean square slope (surface roughness) and surface winds with a 2.8 hour median revisit time from 38 S to 38 N degrees latitude. In addition to the calibration and validation of CYGNSS sea state observations, the CYGNSS science team is assessing the ability of the mission to provide estimates of cyclone size, intensity, and integrated kinetic energy. With its all-weather ability and high temporal resolution, the CYGNSS mission will add significantly to our ability to monitor cyclone genesis and intensification and will significantly reduce uncertainties in our ability to estimate cyclone intensity, a key variable in predicting its destructive potential. Members of the CYGNSS Science Team are also assessing the assimilation of CYGNSS data into hurricane forecast models to determine the impact of the data on forecast skill, using the data to study extra-tropical cyclones, and looking at connections between tropical cyclones and global scale weather, including the global hydrologic cycle. This presentation will focus on the assessment of early on-orbit observations of cyclones with respect to these various applications.

Navigation Performance of Global Navigation Satellite Systems in the Space Service Volume

NASA Technical Reports Server (NTRS)

Force, Dale A.

2013-01-01

GPS has been used for spacecraft navigation for many years center dot In support of this, the US has committed that future GPS satellites will continue to provide signals in the Space Service Volume center dot NASA is working with international agencies to obtain similar commitments from other providers center dot In support of this effort, I simulated multi-constellation navigation in the Space Service Volume In this presentation, I extend the work to examine the navigational benefits and drawbacks of the new constellations center dot A major benefit is the reduced geometric dilution of precision (GDOP). I show that there is a substantial reduction in GDOP by using all of the GNSS constellations center dot The increased number of GNSS satellites broadcasting does produce mutual interference, raising the noise floor. A near/far signal problem can also occur where a nearby satellite drowns out satellites that are far away. - In these simulations, no major effect was observed Typically, the use of multi-constellation GNSS navigation improves GDOP by a factor of two or more over GPS alone center dot In addition, at the higher altitudes, four satellite solutions can be obtained much more often center dot This show the value of having commitments to provide signals in the Space Service Volume Besides a commitment to provide a minimum signal in the Space Service Volume, detailed signal gain information is useful for mission planning center dot Knowledge of group and phase delay over the pattern would also reduce the navigational uncertainty

Estimating Tropical Cyclone Surface Wind Field Parameters with the CYGNSS Constellation

NASA Astrophysics Data System (ADS)

Morris, M.; Ruf, C. S.

2016-12-01

A variety of parameters can be used to describe the wind field of a tropical cyclone (TC). Of particular interest to the TC forecasting and research community are the maximum sustained wind speed (VMAX), radius of maximum wind (RMW), 34-, 50-, and 64-kt wind radii, and integrated kinetic energy (IKE). The RMW is the distance separating the storm center and the VMAX position. IKE integrates the square of surface wind speed over the entire storm. These wind field parameters can be estimated from observations made by the Cyclone Global Navigation Satellite System (CYGNSS) constellation. The CYGNSS constellation consists of eight small satellites in a 35-degree inclination circular orbit. These satellites will be operating in standard science mode by the 2017 Atlantic TC season. CYGNSS will provide estimates of ocean surface wind speed under all precipitating conditions with high temporal and spatial sampling in the tropics. TC wind field data products can be derived from the level-2 CYGNSS wind speed product. CYGNSS-based TC wind field science data products are developed and tested in this paper. Performance of these products is validated using a mission simulator prelaunch.

Constellation labeling optimization for bit-interleaved coded APSK

NASA Astrophysics Data System (ADS)

Xiang, Xingyu; Mo, Zijian; Wang, Zhonghai; Pham, Khanh; Blasch, Erik; Chen, Genshe

2016-05-01

This paper investigates the constellation and mapping optimization for amplitude phase shift keying (APSK) modulation, which is deployed in Digital Video Broadcasting Satellite - Second Generation (DVB-S2) and Digital Video Broadcasting - Satellite services to Handhelds (DVB-SH) broadcasting standards due to its merits of power and spectral efficiency together with the robustness against nonlinear distortion. The mapping optimization is performed for 32-APSK according to combined cost functions related to Euclidean distance and mutual information. A Binary switching algorithm and its modified version are used to minimize the cost function and the estimated error between the original and received data. The optimized constellation mapping is tested by combining DVB-S2 standard Low-Density Parity-Check (LDPC) codes in both Bit-Interleaved Coded Modulation (BICM) and BICM with iterative decoding (BICM-ID) systems. The simulated results validate the proposed constellation labeling optimization scheme which yields better performance against conventional 32-APSK constellation defined in DVB-S2 standard.

Transitions Towards Operational Space-Based Ocean Observations: From Single Research Missions into Series and Constellations

DTIC Science & Technology

2011-02-16

Meleorol. Soc... 88 (8). 1197-121.1. 2007 . (DOI: 10.1175/ BAMS-88-8-1197) 4. GCOS Implementation Plan for the Global Observing System for Climate...21-25 September 2009, Hall, J.. Harrison 1) 1 and Stammer . D., Eds., ESA Publication WPP-306, 2010. 6. Le Traon, P.-Y.. and Co-Authors (2010...Information for Society" Conference (Vol. 2), Venice, Italy, 21-25 September 2009, Hall, J., Harrison D.E. and Stammer , D., Eds., ESA Publication WPP

Ubiquitous and continuous SAR imaging for natural hazards: present and future of remote sensing

NASA Astrophysics Data System (ADS)

Monti Guarnieri, Andrea; Rocca, Fabio

2017-04-01

Constellation of optical and SAR sensors have achieved unprecedented performances: dense constellation of cubesats - like the next constellation of 88 Dove satellites (Planet labs), launched simultaneously this February - reduce the revisit time to nearly daily. This brings great value to many domains, like the assessment of risk and damage in natural hazards, post-earthquake response, real time flood monitoring. The limits to optical imaging due to cloud coverage could then be removed with drones. Alternatively, decades of coherent exploitation of Synthetic Aperture Radars have demonstrated their unique capabilities in precise deformation monitoring, penetration in canopies and subsurfaces (glacier and deserts), 3D imaging of volumes, sensitivity to soil moisture and generation of water vapor maps. Thanks to these capabilities, for one, early warning was possible for a landslide at Bingham Canyon Mine (one of the largest in history), whereas monitoring of infrastructures, natural gas and carbon dioxide storage reservoirs, dams, mines is already an established business. Many of these applications are made possible by the Sentinel-1 SAR constellation, the first to provide systematic coherent acquisitions and free and open data. More than 50000 products are downloaded daily. Nonetheless, the present revisit times of this constellation (1-3 days), or the future 6 hours of Cosmo-SKYmed I and II constellations, will leave a gap that cannot be fruitfully exploited for early warning of landslides, real time mapping of flooding, hydrometeor forecasts, real-time regional alerts of collapse, continuous soil moisture mapping for precision farming. On the other side, the limited penetration capabilities of C-band (Sentinel-1) and X band (Cosmo, TerraSAR constellations) would not allow sufficient penetration to monitor volumes, like ice, sands and forests. In order to fill these gaps, two novel SAR systems are under study and will possibly appear in the next decades: geosynchronous systems and bistatic constellations. The geosynchronous SAR exploits the geostationary orbit to create a hundred kilometers wide real antenna, fixed in the sky, if relative to the ground. If one satellite is exploited, the full antenna would be spanned in twelve hours, and images of medium resolution (ten meter or so) could be got every one-two hours, and finally coarse resolution products, like water vapor or soil moisture maps for flash-flood now-casting, could be generated every fifteen minutes. However, thanks to the intrinsic possibility of phase coherence of the microwaves, a constellation of mini or microsatellites could be deployed to act as a single instrument. Power and resolution would improve with the number of satellites squared, and the revisit would be reduced to minutes. This would be a unique system to provide day-and-night, all-weather imaging capabilities with the additional coherent Radar capabilities to monitor deformations, water-vapor, volumes, soil moisture. The bistatic SAR companion is a passive satellite (or a constellation of) flying in close formation with an active one. Such a system would provide the same capabilities of present TanDEM-X constellation, but enhanced to 3D volume penetration if L band is used.

CarbonSat Constellation

NASA Astrophysics Data System (ADS)

Sun, Wei; Tobehn, Carsten; Ernst, Robert; Bovensmann, Heinrich; Buchwitz, Michael; Burrows, John P.; Notholt, John

1 Carbon dioxide (CO2) and methane (CH4) are the most important manmade greenhouse gases (GHGs) which are driving global climate change. Currently, the CO2 measurements from the ground observing network are still the main sources of information but due to the limited number of measurement stations the coverage is limited. In addition, CO2 monitoring and trading is often based mainly on bottom-up calculations and an independent top down verification is limited due to the lack of global measurement data with local resolution. The first CO2 and CH4 mapping from SCIAMACHY on ENVISAT shows that satellites add important missing global information. Current GHG measurement satellites (GOSAT)are limited either in spatial or temporal resolution and coverage. These systems have to collect data over a year or even longer to produce global regional fluxes products. Conse-quently global, timely, higher spatial resolution and high accuracy measurement are required for: 1. A good understanding of the CO2 and CH4 sources and sinks for reliable climate predic-tion; and 2. Independent and transparent verification of accountable sources and sinks in supporting Kyoto and upcoming protocols The CarbonSat constellation idea comes out the trade off of resolution and swath width during CarbonSat mission definition studies. In response to the urgent need to support the Kyoto and upcoming protocols, a feasibility study has been carried out. The proposed solution is a constellation of five CarbonSat satellites in 614km LTAN 13:00, which is able to provide global, daily CO2 and CH4 measurement everywhere on the Earth with high spatial resolution 2 × 2 km and low uncertainty lt;2ppm (CO2) and lt;8ppb (CH4). The unique global daily measurement capability significantly increases the number of cloud free measurements, which enables more reliable services associated with reduced uncertainty, e.g. to 0.15ppm (CO2) per month in 10km and even more timely products. The CarbonSat Constellation in combination with inverse modelling techniques will be able to provide information services, such as global quarterly 1. CO2 and CH4 regional flux updates 2. CO2 emission reporting from hot spots e.g. the power plant 3. CH4 emission reporting from hot spots e.g. the pipeline/oil and gas fields. The team led by the industry partner -OHB now promotes an internationally coordinated CarbonSat constellation to provide operational services contributing to the independent iden-tification and verification of man-made & natural CO2 and CH4 emissions and claimed carbon sinks. It is proposed that the CarbonSat Constellation will be implemented through an internation-ally coordinated constellation. Each country contributes one satellite in the constellation and establishes its own ground station to provide data for national applications. A central coordi-nation will be set up for the constellation operation, data calibration and international data distribution. The proposed approach provides independence for each partner and is financially more feasible. In addition, the CarbonSat Constellation consortium could be a bridge/forum between developed countries and developing countries in establishing common understandings of and actions on the global climate change. The world wide transparency provided by this international forum is also critical in supporting Kyoto protocol and upcoming international agreement in man-made Greenhouse emission reduction. The paper will present the CarbonSat Constellation design and the proposed products/ services to verify CO2 and CH4 sources and sinks from a constellation of five CarbonSat satellites through a multilateral collaboration.

Constellation Program Update

NASA Image and Video Library

2006-06-04

NASA Administrator Michael Griffin is seen through a television camera at a NASA Update announcing to NASA employees and members of the media the responsibilities of the NASA centers associated with the Constellation Program for robotic and human Moon and Mars exploration on Wednesday, June 5, 2006, at NASA Headquarters in Washington. Griffin was joined by Scott J. Horowitz, NASA Associate Administrator for Exploration Systems and Jeff Hanley, Constellation Program Manager, right. Dean Acosta, NASA Deputy Assistant Administrator and Press Secretary, far left, moderates the program. Photo Credit: (NASA/Bill Ingalls)

Life Support Requirements and Challenges for NASA's Constellation Program

NASA Technical Reports Server (NTRS)

Carasquillo, Robyn

2007-01-01

NASA's Constellation Program, which includes the mission objectives of establishing a permanently-manned lunar Outpost, and the exploration of Mars, poses new and unique challenges for human life support systems that will require solutions beyond the Shuttle and International Space Station state of the art systems. In particular, the requirement to support crews for 210 days duration at the lunar outpost with limited resource resupply capability wilt require closed-loop regenerative life support systems with minimal expendables. Planetary environmental conditions such as lunar dust and extreme temperatures, as well as the capability to support frequent and extended-duration EVA's will be particularly challenging. This presentation will summarize the key program and mission life support requirements for the Constellation Program and the unique challenges they present for technology and architecture development.

On the optimum signal constellation design for high-speed optical transport networks.

PubMed

Liu, Tao; Djordjevic, Ivan B

2012-08-27

In this paper, we first describe an optimum signal constellation design algorithm, which is optimum in MMSE-sense, called MMSE-OSCD, for channel capacity achieving source distribution. Secondly, we introduce a feedback channel capacity inspired optimum signal constellation design (FCC-OSCD) to further improve the performance of MMSE-OSCD, inspired by the fact that feedback channel capacity is higher than that of systems without feedback. The constellations obtained by FCC-OSCD are, however, OSNR dependent. The optimization is jointly performed together with regular quasi-cyclic low-density parity-check (LDPC) code design. Such obtained coded-modulation scheme, in combination with polarization-multiplexing, is suitable as both 400 Gb/s and multi-Tb/s optical transport enabling technology. Using large girth LDPC code, we demonstrate by Monte Carlo simulations that a 32-ary signal constellation, obtained by FCC-OSCD, outperforms previously proposed optimized 32-ary CIPQ signal constellation by 0.8 dB at BER of 10(-7). On the other hand, the LDPC-coded 16-ary FCC-OSCD outperforms 16-QAM by 1.15 dB at the same BER.

Multi-agent robotic systems and applications for satellite missions

NASA Astrophysics Data System (ADS)

Nunes, Miguel A.

A revolution in the space sector is happening. It is expected that in the next decade there will be more satellites launched than in the previous sixty years of space exploration. Major challenges are associated with this growth of space assets such as the autonomy and management of large groups of satellites, in particular with small satellites. There are two main objectives for this work. First, a flexible and distributed software architecture is presented to expand the possibilities of spacecraft autonomy and in particular autonomous motion in attitude and position. The approach taken is based on the concept of distributed software agents, also referred to as multi-agent robotic system. Agents are defined as software programs that are social, reactive and proactive to autonomously maximize the chances of achieving the set goals. Part of the work is to demonstrate that a multi-agent robotic system is a feasible approach for different problems of autonomy such as satellite attitude determination and control and autonomous rendezvous and docking. The second main objective is to develop a method to optimize multi-satellite configurations in space, also known as satellite constellations. This automated method generates new optimal mega-constellations designs for Earth observations and fast revisit times on large ground areas. The optimal satellite constellation can be used by researchers as the baseline for new missions. The first contribution of this work is the development of a new multi-agent robotic system for distributing the attitude determination and control subsystem for HiakaSat. The multi-agent robotic system is implemented and tested on the satellite hardware-in-the-loop testbed that simulates a representative space environment. The results show that the newly proposed system for this particular case achieves an equivalent control performance when compared to the monolithic implementation. In terms on computational efficiency it is found that the multi-agent robotic system has a consistent lower CPU load of 0.29 +/- 0.03 compared to 0.35 +/- 0.04 for the monolithic implementation, a 17.1 % reduction. The second contribution of this work is the development of a multi-agent robotic system for the autonomous rendezvous and docking of multiple spacecraft. To compute the maneuvers guidance, navigation and control algorithms are implemented as part of the multi-agent robotic system. The navigation and control functions are implemented using existing algorithms, but one important contribution of this section is the introduction of a new six degrees of freedom guidance method which is part of the guidance, navigation and control architecture. This new method is an explicit solution to the guidance problem, and is particularly useful for real time guidance for attitude and position, as opposed to typical guidance methods which are based on numerical solutions, and therefore are computationally intensive. A simulation scenario is run for docking four CubeSats deployed radially from a launch vehicle. Considering fully actuated CubeSats, the simulations show docking maneuvers that are successfully completed within 25 minutes which is approximately 30% of a full orbital period in low earth orbit. The final section investigates the problem of optimization of satellite constellations for fast revisit time, and introduces a new method to generate different constellation configurations that are evaluated with a genetic algorithm. Two case studies are presented. The first is the optimization of a constellation for rapid coverage of the oceans of the globe in 24 hours or less. Results show that for an 80 km sensor swath width 50 satellites are required to cover the oceans with a 24 hour revisit time. The second constellation configuration study focuses on the optimization for the rapid coverage of the North Atlantic Tracks for air traffic monitoring in 3 hours or less. The results show that for a fixed swath width of 160 km and for a 3 hour revisit time 52 satellites are required.

Attribute and topology based change detection in a constellation of previously detected objects

DOEpatents

Paglieroni, David W.; Beer, Reginald N.

2016-01-19

A system that applies attribute and topology based change detection to networks of objects that were detected on previous scans of a structure, roadway, or area of interest. The attributes capture properties or characteristics of the previously detected objects, such as location, time of detection, size, elongation, orientation, etc. The topology of the network of previously detected objects is maintained in a constellation database that stores attributes of previously detected objects and implicitly captures the geometrical structure of the network. A change detection system detects change by comparing the attributes and topology of new objects detected on the latest scan to the constellation database of previously detected objects.

A study on making a Honsang using the star catalogue from 『Seong Gyeong』

NASA Astrophysics Data System (ADS)

Ham, Seon Young; Kim, Sang Hyuk; Lee, Yong Sam

2016-01-01

The first record of Honsang (Celestial globe) was found in 『Sejong Sillok』 in Korea. Since then, there were records that Honsang was restored during the reign of King Jungjong and King Myungjong, and then restored again in the reign of King Seonjo. The only existing Honsang was made by Yi Hwang (1501-1570) in the 16th century for education of his followers. After then, Hong Dae Yong's (1731-1783) Honsangui, which was made in 18th century, had been passed down only through the literature. The constellations in Honsang and the scale system of each ring changed after 17th century when Western science began to affect Joseon dynasty. Since that time, the constellations, realized on Honsang globe, changed from constellations in the old method to ones in the new method. Furthermore, the scale system of rings on Honsang was changed from 365.25 Do, Jucheondo (Celestial globe circumference), to 360°. In this study, Honsang with constellations in the new method was made using star catalogue from 『Seong Gyeong』 published in 1861, which represented the constellations in the new method of Joseon dynasty. In order to realized the constellations from the star catalogue in 『Seong Gyeong』 on Honsang globe, the plane star chart and circular star chart of the area near the South and North Poles were drawn using spherical trigonometry. Using these star charts, the constellations in whole sky including stars near the South Pole were realized on Honsang globe. Also, equatorial coordinates and ecliptic coordinates were realized on Honsang globe simultaneously, and scales of Honsang's rings were marked as 360°.

Effectiveness of GNSS disposal strategies

NASA Astrophysics Data System (ADS)

Alessi, E. M.; Rossi, A.; Valsecchi, G. B.; Anselmo, L.; Pardini, C.; Colombo, C.; Lewis, H. G.; Daquin, J.; Deleflie, F.; Vasile, M.; Zuiani, F.; Merz, K.

2014-06-01

The management of the Global Navigation Satellite Systems (GNSS) and of the Medium Earth Orbit (MEO) region as a whole is a subject that cannot be deferred, due to the growing exploitation and launch rate in that orbital regime. The advent of the European Galileo and the Chinese Beidou constellations significantly added complexity to the system and calls for an adequate global view on the four constellations present in operation. The operation procedures, including maintenance and disposal practices, of the constellations currently deployed were analyzed in order to asses a proper reference simulation scenario. The complex dynamics of the MEO region with all the geopotential and lunisolar resonances was studied to better identify the proper end-of-life orbit for every proposed strategy, taking into account and, whenever possible, exploiting the orbital dynamics in this peculiar region of space. The possibility to exploit low thrust propulsion or non gravitational perturbations with passive de-orbiting devices (and a combination of the two) was analyzed, in view of possible applications in the design of the future generations of the constellations satellites. Several upgrades in the long-term evolution software SDM and DAMAGE were undertaken to properly handle the constellation simulations in every aspect from constellation maintenance to orbital dynamics. A thorough approach considering the full time evolving covariance matrix associated with every object was implemented in SDM to compute the collision risk and associated maneuver rate for the constellation satellites. Once the software upgrades will be completed, the effectiveness of the different disposal strategies will be analyzed in terms of residual collision risk and avoidance maneuvers rate. This work was performed under the ESA/GSP Contract no. 4000107201/12/F/MOS.

Analysis and design of Cubesat constellation for the Mediterranean south costal monitoring against illegal immigration

NASA Astrophysics Data System (ADS)

Lazreg, Nissen; Ben Bahri, Omar; Besbes, Kamel

2018-02-01

Costal monitoring is focused on fast response to illegal immigration and illegal ship traffic. Especially, the illegal ship traffic has been present in media since April 2015, as the number of reported deaths of immigrants crossing the Mediterranean significantly increased. Satellite images provide a possibility to at least partially control both types of events. This paper defines the principal criteria to select the best satellite constellation architecture for maritime and coastal monitoring, filling the gaps of imagery techniques in term of real-time control. The primary purpose of a constellation is to obtain global measurement improving the temporal resolution. The small size and low-cost are the main factors, which make CubeSats ideal for use in constellations. We propose a constellation of 9 Cubesats distributed evenly in 3 different planes. This reduces the revisit time enhancing the coverage duration. In addition, it also allows observing fire, damage on building and similar disasters. In this analysis, the performance criteria were reported such as the revisit time, the vision duration and the area coverage.

Small Satellite Constellations: The Future for Operational Earth Observation

NASA Technical Reports Server (NTRS)

Stephens, J. Paul

2007-01-01

Nanosat, microsat and minisat are low-cost, rapid-response small-satellites built from advanced terrestrial technology. SSTL delivers the benefits of affordable access to space through low-cost, rapid response, small satellites designed and built with state-of-the-art COTS technologies by: a) reducing the cost of entry into space; b) Achieving more missions within fixed budgets; c) making constellations and formation flying financially viable; d) responding rapidly from initial concept to orbital operation; and e) bringing the latest industrial COTS component advances to space. Growth has been stimulated in constellations for high temporal revisit&persistent monitoring and military responsive space assets.

Constellation Program Update

NASA Image and Video Library

2006-06-04

Dean Acosta, NASA Deputy Assistant Administrator and Press Secretary, left, moderates a NASA Update with NASA Administrator Michael Griffin, Scott J. Horowitz, NASA Associate Administrator for Exploration Systems and Jeff Hanley, Constellation Program Manager, right, on Wednesday, June 5, 2006, at NASA Headquarters in Washington. Photo Credit: (NASA/Bill Ingalls)

Going Beyond Einstein with the Constellation-X Mission

NASA Technical Reports Server (NTRS)

White, Nicholas

2007-01-01

The Constellation-X mission will address the questions: "What happens to matter close to a black hole?" and "What is Dark Energy?" These questions are central to the NASA Beyond Einstein Program, where Constellation-X plays a central role. The mission will address these questions by using high throughput X-ray spectroscopy to observe the effects of strong gravity close to the event horizon of black holes, and to observe the formation and evolution of clusters of galaxies in order to precisely determine Cosmological parameters. To achieve these primary science goals requires a factor of 25-100 increase in sensitivity for high resolution X-ray spectroscopy.'The mission will also perform routine high-resolution X-ray spectroscopy of faint 2nd extended X-ray source populations. This will provide diagnostic information such as density, elemental abundances, velocity; and ionization state for a wide range of astrophysical problems, including new constraints on the Neutron Star equation of state.

Beta Pic observations requested for BRITE-Constellation

NASA Astrophysics Data System (ADS)

Waagen, Elizabeth O.

2017-01-01

The AAVSO is part of the BRITE-Constellation Ground Based Observations Team (GBOT), supporting cutting-edge science from the BRITE-Constellation satellites and coordinating with BRITE-Constellation scientist Dr. Konstanze Zwintz (Universitaet Innsbruck) and her team. The delta Scuti star beta Pic (NSV 16683) (3.80-3.86V) is one of the BRITE stars being focused on during this season. Bet Pic is particularly interesting now because a transit of the star's planet's Hill sphere (the region around a planet in which it dominates the attraction of satellites) is predicted to occur during 2017-2018. Ongoing observations beginning now are valuable to establish a baseline prior to the transit. The AAVSO's webpage on the BRITE target stars was updated in November with information on bet Pic from Dr. Zwintz. AAVSO observers with appropriate equipment and located at a southern enough latitude are encouraged to observe bet Pic. Its brightness makes bet Pic well suited to PEP and DSLR photometry; CCD photometry is also possible. However, great care must be taken by all observers, especially those using CCD, to avoid saturation. As the amplitude of this star is very small, visual observations are very difficult, but they are welcome. Multicolor (BVR) photometry better than 0.01 magnitude and time-series observations with a cadence of a few minutes (less than 10 minutes) are requested beginning now and continuing at least through 2017 and likely through 2018. The precision and cadence required are essential in order for the data to be most useful for studying the transit. Spectroscopists wishing to participate should submit their spectra directly to Dr. Konstanze Zwintz (konstanze.zwintz@uibk.ac.at). Finder charts with sequence may be created using the AAVSO Variable Star Plotter (https://www.aavso.org/vsp). Observations should be submitted to the AAVSO International Database. See full Alert Notice for more details.

Operative planning of functional sessions for multisatellite observation and communication systems

NASA Astrophysics Data System (ADS)

Darnopykh, Valeriy V.; Malyshev, Veniamin V.

2012-04-01

An important control aspect of modern satellite observation and communication systems is the control of the functional processes. Functional sessions proceed under conditions of restricted technical ability, large amounts or information to be processed by the on-board equipment, practice inequality of the received information, intentions of system management and operators, interests of customers and other factors. A large number of spacecrafts (SC) in orbital constellation is one of the most important factors affecting the functional process also. Besides that some modern projects of satellite systems are multifunctional that is mixed operations of observation and communication. Therefore the functioning of SC on-board equipment must be accurately co-ordinate. That is why the problem of operative planning the functioning of these systems, while directly affecting the efficiency of the system, is very complex and actual at present. A methodical approach and software package for operative planning of functional processes for satellite observation and communication systems, including multifunctional projects, are considered in the paper. The base scheme of this approach consists of four main stages: stage 1—modeling of SC orbital kinematics and dynamics; stage 2—modeling of system functional processes with all kind of restrictions and criterion function values; stage 3—solving an optimization tasks by numerical applicable algorithms and constructing the optimal (or accuracy) plans; stage 4—repeated plan optimization (different variants) and analyzing. Such scheme is the result of authors practical research which have been realized during last 15 years by the operative planning as for any kinds of single SC as for satellite systems with different structure of orbital constellation. The research helps to unify the procedure of operative planning, to formulate basic principles and approaches for its solving, to develop special software package. The main aspects of the approach proposed are illustrated in the paper. The results of the calculations of applied planning problems are presented. The objects of research in these problems are: projects of CBERS observation systems (1-3 SC) and projects of Iridium (66 SC) global communication system.

Determination of motion extrema in multi-satellite systems

NASA Astrophysics Data System (ADS)

Allgeier, Shawn E.

Spacecraft, or satellite formation flight has been a topic of interest dating back to the Gemini program of the 1960s. Traditionally space missions have been designed around large monolithic assets. Recent interest in low cost, rapid call up mission architectures structured around fractionated systems, small satellites, and constellations has spurred renewed efforts in spacecraft relative motion problems. While such fractionated, or multi-body systems may provide benefits in terms of risk mitigation and cost savings, they introduce new technical challenges in terms of satellite coordination. Characterization of satellite formations is a vital requirement for them to have utility to industry and government entities. Satellite formations introduce challenges in the form of constellation maintenance, inter-satellite communications, and the demand for more sophisticated guidance, navigation, and control systems. At the core of these challenges is the orbital mechanics which govern the resulting motion. New applications of algebraic techniques are applied to the formation flight problem, specifically Gröbner basis tools, as a means of determining extrema of certain quantities pertaining to formation flight. Specifically, bounds are calculated for the relative position components, relative speed, relative velocity components, and range rate. The position based metrics are relevant for planning formation geometry, particularly in constellation or Earth observation applications. The velocity metrics are relevant in the design of end game interactions for rendezvous and proximity operations. The range rate of one satellite to another is essential in the design of radio frequency hardware for inter-satellite communications so that the doppler shift can be calculated a priori. Range rate may also have utility in space based surveillance and space situational awareness concerns, such as cross tagging. The results presented constitute a geometric perspective and have utility to mission designers, particularly for missions involving rendezvous and proximity operations.

Constellation Program Update

NASA Image and Video Library

2006-06-04

Scott J. Horowitz, NASA Associate Administrator for Exploration Systems, announces to NASA employees and members of the media the responsibilities of the NASA centers associated with the Constellation Program for robotic and human Moon and Mars exploration on Wednesday, June 5, 2006, at NASA Headquarters in Washington. Photo Credit: (NASA/Bill Ingalls)

Water: Communicator In Moon-Earth Relationships

NASA Astrophysics Data System (ADS)

Davis, Joan S.

The Moon's myriad effects upon Earth have been objects of fascination, and subjects for literary works and scientific speculation throughout history. Although many of Moon's influences upon Earth involve water, tidal movement is clearly the most readily associated effect. While very obvious, it however represents only one of a multitude of ways in which lunar forces effect this planet, and all life upon it. Much less apparent, though essential for all of life, is the wide spectrum of subtle fluctuating influences upon the water in the cells of living systems. Water's capacity to respond to extremely subtle changes in physical influences (such as gravitational fields), as associated with Moon phases (N.B. also with planetary constellations and sunspot activity), enables it to communicate such inputs to living systems. The periodicity of changes in natural systems has been of interest to man throughout history. However, only in more recent times has insight into water's behaviour led to its being recognised as a link between the periodicities seen in abiotic (Moon and other planetary) systems and biotic systems. Particular attention has long been paid to systematic fluctuations in agriculture and forestry: Different growth patterns are observed in connection with the Moon phases (and zodiac constellations) at planting time; different characteristics (e.g., fire resistance, pliability, firmness, etc.) of wood are seen in trees harvested at different phases and constellations. . The usefulness of such correlations has influenced planting and harvesting patterns in more traditional-oriented agriculture and forestry. Its acceptance by science has, however, been long in coming. The case similar, as regards physiological fluctuations observed in the medical field. A documented case in point is the correlation between the Moon-phase and risk of hemorrhage during surgery: This is one of many observations on periodicity in body functions, which deserve more research attention than they receive. . Direct measurements of physical parameters of water (such as surface tension, solution constants), which respond to subtle influences, such as weak magnetic fields, could concievably benefit insight into the role of water as communicator of `information' to both biotic and abiotic systems. The same approach would apply for research on other sources of subtle influences such as planetary constellations and sunspot activity (N.B. this is well documented in its effects upon aqueous reactions; the eleven year periodicity is clearly recognisable). . In turn, insight into water's role could lead to more recognition and acceptance of such significant, though subtle, effects upon living systems … and with this, a more appropriate consideration of their consequences and their relevance for many of man's activities. . The fact that science has been so reticent to recognize and accept the lunar effects upon the Earth and its inhabitants, is in part due to its insufficient understanding of water. Current research on its structure and its behaviour can help us understand how water can serve as communicator of information between Moon and Earth. And thus also to recognise the significance of the subtle, life-supporting regulation the Moon provides to our planet.

Ultra high frequency follow-on communications satellite system

NASA Astrophysics Data System (ADS)

Hassien, Michael J.

1992-03-01

The existing constellation of UHF communications satellites (LEASAT and FLTSAT) provide key command and control links for mobile forces of the DoD and other government agencies. The UHF Follow-On satellite program will provide for a new generation of communications satellites to replace the existing ones as they reach the end of their life cycle beginning in 1992. Continued coverage is required for both peacetime and crisis environments, and must be maintained indefinitely. An eight-satellite UFO constellation (two per coverage area) will replenish the existing FLTSATCOM constellation.

1993 Earth Observing System reference handbook

NASA Technical Reports Server (NTRS)

Asrar, Ghassem (Editor); Dokken, David Jon (Editor)

1993-01-01

Mission to Planet Earth (MTPE) is a NASA-sponsored concept that uses space- and ground-based measurement systems to provide the scientific basis for understanding global change. The space-based components of MTPE will provide a constellation of satellites to monitor the Earth from space. Sustained observations will allow researchers to monitor climate variables overtime to determine trends; however, space-based monitoring alone is not sufficient. A comprehensive data and information system, a community of scientists performing research with the data acquired, and extensive ground campaigns are all important components. Brief descriptions of the various elements that comprise the overall mission are provided. The Earth Observing System (EOS) - a series of polar-orbiting and low-inclination satellites for long-term global observations of the land surface, biosphere, solid Earth, atmosphere, and oceans - is the centerpiece of MTPE. The elements comprising the EOS mission are described in detail.

Constellation Program Update

NASA Image and Video Library

2006-06-04

Dean Acosta, NASA Deputy Assistant Administrator and Press Secretary, left, moderates a NASA Update with NASA Administrator Michael Griffin, second from left, Scott J. Horowitz, NASA Associate Administrator for Exploration Systems and Jeff Hanley, Constellation Program Manager, right, on Wednesday, June 5, 2006, at NASA Headquarters in Washington. Photo Credit: (NASA/Bill Ingalls)

The Constellation-X Mission: Science Prospects and Technology Challenges

NASA Technical Reports Server (NTRS)

Petre, Robert

2007-01-01

This talk will describe the Constellation-X mission. It will present the key scientific goals, relating to strong gravity, dark energy, ultra-dense matter and cosmic structure. The mission configuration will be described. Emphasis will be placed on the design and anticipated implementation of the X-ray mirror system.

Mitigation of Volcanic Risk: The COSMO-SkyMed Contribution

NASA Astrophysics Data System (ADS)

Sacco, Patrizia; Daraio, Maria Girolamo; Battagliere, Maria Libera; Coletta, Alessandro

2015-05-01

The Italian Space Agency (ASI) promotes Earth Observation (EO) applications related to themes such as the prediction, monitoring, management and mitigation of natural and anthropogenic hazards. The approach generally followed is the development and demonstration of prototype services, using currently available data from space missions, in particular the COSMO-SkyMed (Constellation of Small Satellites for Mediterranean basin observation) mission, which represents the largest Italian investment in Space System for EO and thanks to which Italy plays a key role worldwide. Projects funded by ASI provide the convergence of various national industry expertise, research and institutional reference users. In this context a significant example is represented by the ASI Pilot Projects, recently concluded, dealing with various thematic, such as volcanoes. In this paper a special focus will be addressed to the volcanic risk management and the contribution provided in this field by COSMO-SkyMed satellite constellation during the last years. A comprehensive overview of the various national and international projects using COSMO-SkyMed data for the volcanic risk mitigation will be given, highlighting the Italian contribution provided worldwide in this operational framework.

Constellation Program Lessons Learned in the Quantification and Use of Aerodynamic Uncertainty

NASA Technical Reports Server (NTRS)

Walker, Eric L.; Hemsch, Michael J.; Pinier, Jeremy T.; Bibb, Karen L.; Chan, David T.; Hanke, Jeremy L.

2011-01-01

The NASA Constellation Program has worked for the past five years to develop a re- placement for the current Space Transportation System. Of the elements that form the Constellation Program, only two require databases that define aerodynamic environments and their respective uncertainty: the Ares launch vehicles and the Orion crew and launch abort vehicles. Teams were established within the Ares and Orion projects to provide repre- sentative aerodynamic models including both baseline values and quantified uncertainties. A technical team was also formed within the Constellation Program to facilitate integra- tion among the project elements. This paper is a summary of the collective experience of the three teams working with the quantification and use of uncertainty in aerodynamic environments: the Ares and Orion project teams as well as the Constellation integration team. Not all of the lessons learned discussed in this paper could be applied during the course of the program, but they are included in the hope of benefiting future projects.

Dynamic replanning on demand of UAS constellations performing ISR missions

NASA Astrophysics Data System (ADS)

Stouch, Daniel W.; Zeidman, Ernest; Callahan, William; McGraw, Kirk

2011-05-01

Unmanned aerial systems (UAS) have proven themselves to be indispensable in providing intelligence, surveillance, and reconnaissance (ISR) over the battlefield. Constellations of heterogeneous, multi-purpose UAS are being tasked to provide ISR in an unpredictable environment. This necessitates the dynamic replanning of critical missions as weather conditions change, new observation targets are identified, aircraft are lost or equipment malfunctions, and new airspace restrictions are introduced. We present a method to generate coordinated mission plans for constellations of UAS with multiple flight goals and potentially competing objectives, and update them on demand as the operational situation changes. We use a fast evolutionary algorithm-based, multi-objective optimization technique. The updated flight routes maintain continuity by considering where the ISR assets have already flown and where they still need to go. Both the initial planning and replanning take into account factors such as area of analysis coverage, restricted operating zones, maximum control station range, adverse weather effects, military terrain value, and sensor performance. Our results demonstrate that by constraining the space of potential solutions using an intelligently-formed air maneuver network with a subset of potential airspace corridors and navigational waypoints, we can ensure global optimization for multiple objectives considering the situation both before and after the replanning is initiated. We employ sophisticated visualization techniques using a geographic information system to help the user 'look under the hood" of the algorithms to understand the effectiveness and viability of the generated ISR mission plans and identify potential gaps in coverage.

[Fragile X syndrome with Dandy-Walker variant: a clinical study of oral and written communicative manifestations].

PubMed

Lamônica, Dionísia Aparecida Cusin; Ferraz, Plínio Marcos Duarte Pinto; Ferreira, Amanda Tragueta; Prado, Lívia Maria do; Abramides, Dagma Venturini Marquez; Gejão, Mariana Germano

2011-01-01

The Fragile X syndrome is the most frequent cause of inherited intellectual disability. The Dandy-Walker variant is a specific constellation of neuroradiological findings. The present study reports oral and written communication findings in a 15-year-old boy with clinical and molecular diagnosis of Fragile X syndrome and neuroimaging findings consistent with Dandy-Walker variant. The speech-language pathology and audiology evaluation was carried out using the Communicative Behavior Observation, the Phonology assessment of the ABFW - Child Language Test, the Phonological Abilities Profile, the Test of School Performance, and the Illinois Test of Psycholinguistic Abilities. Stomatognathic system and hearing assessments were also performed. It was observed: phonological, semantic, pragmatic and morphosyntactic deficits in oral language; deficits in psycholinguistic abilities (auditory reception, verbal expression, combination of sounds, auditory and visual sequential memory, auditory closure, auditory and visual association); and morphological and functional alterations in the stomatognathic system. Difficulties in decoding the graphical symbols were observed in reading. In writing, the subject presented omissions, agglutinations and multiple representations with the predominant use of vowels, besides difficulties in visuo-spatial organization. In mathematics, in spite of the numeric recognition, the participant didn't accomplish arithmetic operations. No alterations were observed in the peripheral hearing evaluation. The constellation of behavioral, cognitive, linguistic and perceptual symptoms described for Fragile X syndrome, in addition to the structural central nervous alterations observed in the Dandy-Walker variant, caused outstanding interferences in the development of communicative abilities, in reading and writing learning, and in the individual's social integration.

Combined trellis coding with asymmetric MPSK modulation: An MSAT-X report

NASA Technical Reports Server (NTRS)

Simon, M. K.; Divsalar, D.

1985-01-01

Traditionally symmetric, multiple phase-shift-keyed (MPSK) signal constellations, i.e., those with uniformly spaced signal points around the circle, have been used for both uncoded and coded systems. Although symmetric MPSK signal constellations are optimum for systems with no coding, the same is not necessarily true for coded systems. This appears to show that by designing the signal constellations to be asymmetric, one can, in many instances, obtain a significant performance improvement over the traditional symmetric MPSK constellations combined with trellis coding. The joint design of n/(n + 1) trellis codes and asymmetric 2 sup n + 1 - point MPSK is considered, which has a unity bandwidth expansion relative to uncoded 2 sup n-point symmetric MPSK. The asymptotic performance gains due to coding and asymmetry are evaluated in terms of the minimum free Euclidean distance free of the trellis. A comparison of the maximum value of this performance measure with the minimum distance d sub min of the uncoded system is an indication of the maximum reduction in required E sub b/N sub O that can be achieved for arbitrarily small system bit-error rates. It is to be emphasized that the introduction of asymmetry into the signal set does not effect the bandwidth of power requirements of the system; hence, the above-mentioned improvements in performance come at little or no cost. MPSK signal sets in coded systems appear in the work of Divsalar.

ARGOS - the Laser Star Adaptive Optics for LBT

NASA Astrophysics Data System (ADS)

Rabien, S.; Barl, L.; Beckmann, U.; Blümchen, T.; Bonaglia, M.; Borelli, J. L.; Brynnel, J.; Busoni, L.; Carbonaro, L.; Conot, C.; Davies, R.; Deysenroth, M.; Durney, O.; Elberich, M.; Esposito, S.; Gasho, V.; Gässler, W.; Gemperlein, H.; Genzel, R.; Green, R.; Haug, M.; Lloyd Hart, M.; Hubbard, P.; Kanneganti, S.; Kulas, M.; Noenickx, J.; Peter, D.; Quirrenbach, A.; Rademacher, M.; Rix, H. W.; Salinari, P.; Schwab, C.; Storm, J.; Strüder, L.; Thiel, M.; Weigelt, G.; Ziegleder, J.; Orban de Xivry, G.

2011-09-01

We will present the design and status of ARGOS - the Laser Guide Star adaptive optics facility for the Large Binocular Telescope. By projecting a constellation of multiple laser guide stars above each of the 8.4m primary mirrors of the LBT, ARGOS in its ground layer mode will enable a wide field adaptive optics correction for multi object spectroscopy. ARGOS implements high power pulsed green lasers and makes use of Rayleigh scattering for the guide star creation. The geometric relations of this setup in guide star height vs. primary diameter are quite comparable to an ELT with sodium guide stars. The use of LBT's adaptive secondary mirror, gated wavefront sensors, a prime focus calibration system and the laser constellation shows several aspects that may be used as pathfinding technology for the planned ELTs. In already planned upgrade steps with a hybrid Sodium-Rayleigh combination ARGOS will enable MCAO and MOAO implementations at LBT allowing unique astronomical observations.

High Resolution X-Band SAR Constallation for Risk Management

DTIC Science & Technology

2000-10-01

polarisation has been specified to two unique, alternative SAR-satellite designs which as no specific requirement exists for dual- polarisation combine...dispersion while Fig. 4a). beam -scanning; 5 azimuth power splitters which feed the sub- 2. An architecture borrowed from modem panels...resolution SAR constellation therefore forms an essential Polarisation HH (or VV) component of such an observation system which shall Mean/max revisit < 12/24

Exploring the Architectural Tradespace of Severe Weather Monitoring Nanosatellite Constellations

NASA Astrophysics Data System (ADS)

Hitomi, N.; Selva, D.; Blackwell, W. J.

2014-12-01

MicroMAS-1, a 3U nanosatellite developed by MIT/LL, MIT/SSL, and University of Massachusetts, was launched on July 13, 2014 and is scheduled for deployment from the International Space Station in September. The development of MicroMAS motivates an architectural analysis of a constellation of nanosatellites with the goal of drastically reducing the cost of observing severe storms compared with current monolithic missions such as the Precision and All-Weather Temperature and Humidity (PATH) mission from the NASA Decadal Survey. Our goal is to evolve the instrument capability on weather monitoring nanosatellites to achieve higher performance and better satisfy stakeholder needs. Clear definitions of performance requirements are critical in the conceptual design phase when much of the project's lifecycle cost and performance will be fixed. Ability to perform trade studies and optimization of performance needs with instrument capability will enable design teams to focus on key technologies that will introduce high value and high return on investment. In this work, we approach the significant trades and trends of constellations for monitoring severe storms by applying our rule-based decision support tool. We examine a subset of stakeholder groups listed in the OSCAR online database (e.g., weather, climate) that would benefit from severe storm weather data and their respective observation requirements (e.g. spatial resolution, accuracy). We use ten parameters in our analysis, including atmospheric temperature, humidity, and precipitation. We compare the performance and cost of thousands of different possible constellations. The constellations support hyperspectral sounders that cover different portions of the millimeter-wave spectrum (50-60 GHz, 118GHz, 183GHz) in different orbits, and the performance results are compared against those of the monolithic PATH mission. Our preliminary results indicate that constellations using the hyperspectral millimeter wave sounders can better satisfy stakeholder needs compared to the PATH mission. Well-architected constellations have increased coverage, improved horizontal resolution from lower orbits, and improved temporal resolution. Furthermore, this improved performance can be achieved at a lower cost than what is estimated for the PATH mission.

The Impact of Estimating High-Resolution Tropospheric Gradients on Multi-GNSS Precise Positioning

PubMed Central

Zhou, Feng; Li, Xingxing; Li, Weiwei; Chen, Wen; Dong, Danan; Wickert, Jens; Schuh, Harald

2017-01-01

Benefits from the modernized US Global Positioning System (GPS), the revitalized Russian GLObal NAvigation Satellite System (GLONASS), and the newly-developed Chinese BeiDou Navigation Satellite System (BDS) and European Galileo, multi-constellation Global Navigation Satellite System (GNSS) has emerged as a powerful tool not only in positioning, navigation, and timing (PNT), but also in remote sensing of the atmosphere and ionosphere. Both precise positioning and the derivation of atmospheric parameters can benefit from multi-GNSS observations. In this contribution, extensive evaluations are conducted with multi-GNSS datasets collected from 134 globally-distributed ground stations of the International GNSS Service (IGS) Multi-GNSS Experiment (MGEX) network in July 2016. The datasets are processed in six different constellation combinations, i.e., GPS-, GLONASS-, BDS-only, GPS + GLONASS, GPS + BDS, and GPS + GLONASS + BDS + Galileo precise point positioning (PPP). Tropospheric gradients are estimated with eight different temporal resolutions, from 1 h to 24 h, to investigate the impact of estimating high-resolution gradients on position estimates. The standard deviation (STD) is used as an indicator of positioning repeatability. The results show that estimating tropospheric gradients with high temporal resolution can achieve better positioning performance than the traditional strategy in which tropospheric gradients are estimated on a daily basis. Moreover, the impact of estimating tropospheric gradients with different temporal resolutions at various elevation cutoff angles (from 3° to 20°) is investigated. It can be observed that with increasing elevation cutoff angles, the improvement in positioning repeatability is decreased. PMID:28368346

The Impact of Estimating High-Resolution Tropospheric Gradients on Multi-GNSS Precise Positioning.

PubMed

Zhou, Feng; Li, Xingxing; Li, Weiwei; Chen, Wen; Dong, Danan; Wickert, Jens; Schuh, Harald

2017-04-03

Benefits from the modernized US Global Positioning System (GPS), the revitalized Russian GLObal NAvigation Satellite System (GLONASS), and the newly-developed Chinese BeiDou Navigation Satellite System (BDS) and European Galileo, multi-constellation Global Navigation Satellite System (GNSS) has emerged as a powerful tool not only in positioning, navigation, and timing (PNT), but also in remote sensing of the atmosphere and ionosphere. Both precise positioning and the derivation of atmospheric parameters can benefit from multi-GNSS observations. In this contribution, extensive evaluations are conducted with multi-GNSS datasets collected from 134 globally-distributed ground stations of the International GNSS Service (IGS) Multi-GNSS Experiment (MGEX) network in July 2016. The datasets are processed in six different constellation combinations, i.e., GPS-, GLONASS-, BDS-only, GPS + GLONASS, GPS + BDS, and GPS + GLONASS + BDS + Galileo precise point positioning (PPP). Tropospheric gradients are estimated with eight different temporal resolutions, from 1 h to 24 h, to investigate the impact of estimating high-resolution gradients on position estimates. The standard deviation (STD) is used as an indicator of positioning repeatability. The results show that estimating tropospheric gradients with high temporal resolution can achieve better positioning performance than the traditional strategy in which tropospheric gradients are estimated on a daily basis. Moreover, the impact of estimating tropospheric gradients with different temporal resolutions at various elevation cutoff angles (from 3° to 20°) is investigated. It can be observed that with increasing elevation cutoff angles, the improvement in positioning repeatability is decreased.

Radiometric and geometric assessment of data from the RapidEye constellation of satellites

USGS Publications Warehouse

Chander, Gyanesh; Haque, Md. Obaidul; Sampath, Aparajithan; Brunn, A.; Trosset, G.; Hoffmann, D.; Roloff, S.; Thiele, M.; Anderson, C.

2013-01-01

To monitor land surface processes over a wide range of temporal and spatial scales, it is critical to have coordinated observations of the Earth's surface using imagery acquired from multiple spaceborne imaging sensors. The RapidEye (RE) satellite constellation acquires high-resolution satellite images covering the entire globe within a very short period of time by sensors identical in construction and cross-calibrated to each other. To evaluate the RE high-resolution Multi-spectral Imager (MSI) sensor capabilities, a cross-comparison between the RE constellation of sensors was performed first using image statistics based on large common areas observed over pseudo-invariant calibration sites (PICS) by the sensors and, second, by comparing the on-orbit radiometric calibration temporal trending over a large number of calibration sites. For any spectral band, the individual responses measured by the five satellites of the RE constellation were found to differ <2–3% from the average constellation response depending on the method used for evaluation. Geometric assessment was also performed to study the positional accuracy and relative band-to-band (B2B) alignment of the image data sets. The position accuracy was assessed by comparing the RE imagery against high-resolution aerial imagery, while the B2B characterization was performed by registering each band against every other band to ensure that the proper band alignment is provided for an image product. The B2B results indicate that the internal alignments of these five RE bands are in agreement, with bands typically registered to within 0.25 pixels of each other or better.

United States Frigate Constellation: Monitoring of Water at Constellation Pier, Baltimore Harbor, for the Presence of Marine Wood-Destroyers--First Year of Observations, from April 1978 to May 1979.

DTIC Science & Technology

1980-09-30

10- by 20-cm southern pine sapwood panels spaced approximately 1.5 m (5 ft) apart (center to center) on a supporting line; the lowest panel is...level [91. Such a climatic phenomenon could occur for the Chesapeake Bay area . Fouling Organisms The yearly settlement of epifaunal organisms at

Constellation Program (CxP) Crew Exploration Vehicle (CEV) Parachute Assembly System (CPAS) Independent Design Reliability Assessment. Volume 1

NASA Technical Reports Server (NTRS)

Kelly, Michael J.

2010-01-01

This report documents the activities, findings, and NASA Engineering and Safety Center (NESC) recommendations of a multidiscipline team to independently assess the Constellation Program (CxP) Crew Exploration Vehicle (CEV) Parachute Assembly System (CPAS). This assessment occurred during a period of 15 noncontiguous months between December 2008 and April 2010, prior to the CPAS Project's Preliminary Design Review (PDR) in August 2010.

The Global Precipitation Measurement (GPM) Microwave Imager (GMI): Instrument Overview and Early On-Orbit Performance

NASA Technical Reports Server (NTRS)

Draper, David W.; Newell, David A.; Wentz, Frank J.; Krimchansky, Sergey; Jackson, Gail

2015-01-01

The Global Precipitation Measurement (GPM) mission is an international satellite mission that uses measurements from an advanced radar/radiometer system on a core observatory as reference standards to unify and advance precipitation estimates made by a constellation of research and operational microwave sensors. The GPM core observatory was launched on February 27, 2014 at 18:37 UT in a 65? inclination nonsun-synchronous orbit. GPM focuses on precipitation as a key component of the Earth's water and energy cycle, and has the capability to provide near-real-time observations for tracking severe weather events, monitoring freshwater resources, and other societal applications. The GPM microwave imager (GMI) on the core observatory provides the direct link to the constellation radiometer sensors, which fly mainly in polar orbits. The GMI sensitivity, accuracy, and stability play a crucial role in unifying the measurements from the GPM constellation of satellites. The instrument has exhibited highly stable operations through the duration of the calibration/validation period. This paper provides an overview of the GMI instrument and a report of early on-orbit commissioning activities. It discusses the on-orbit radiometric sensitivity, absolute calibration accuracy, and stability for each radiometric channel. Index Terms-Calibration accuracy, passive microwave remote sensing, radiometric sensitivity.

An Investigation into Establishing a Formation of Small Satellites in a Lunar Flower Constellation

NASA Astrophysics Data System (ADS)

McManus, Lauren

Lunar science missions such as LADEE and GRAIL achieved unprecedented measurements of the Lunar exosphere and gravity field. These missions were performed with one (LADEE) or two (GRAIL) traditional satellites. The global coverage achieved by these missions could have been greatly enhanced with the use of a constellation of satellites. A constellation of communication satellites at the Moon would also be necessary if a Lunar human base were to be established. Constellations with many satellites are expensive with traditional technology, but have become feasible through the technological advancements and affordability of cubesats. Cubesat constellations allow for full surface coverage in science or communication missions at a reasonable mission cost. Repeat ground track orbits offer interesting options for science or communication constellations, since they provide repeat coverage of the surface at a fixed time between sequential visits. Flower constellations are a family of constellations being studied primarily by Daniele Mortari at Texas A&M; University that make use of repeat ground tracks. Orbital parameters are selected such that the nodal period of the orbit matches the nodal period of the primary body by a factor dependent on the number of days and the number of revolutions to repeat the ground track. All orbits in a flower constellation have identical orbital elements, with the exception of the right ascension of the ascending node (RAAN) and the initial mean anomaly, which are determined based on the desired phasing scheme desired. Flower constellations have thus far primarily been studied at Earth. A flower constellation at the Moon could be quite useful for science or communication purposes. In this scenario, the flower constellation satellites would be small satellites, which introduces many unique challenges. The cubesats would have limited propulsion capability and would need to be deployed from a mothercraft. Orbital maintenance would then be required after deployment to retain the repeat ground track nature of flower constellations. The limited fuel on the cubesats and the maneuvers required determine the lifetime of the constellation. The communications range of the cubesats will also be limited; following a successful deployment, the mothercraft must move into a long-term communications orbit where it can see both the children craft and Earth, to act as a communications relay. This work investigates the differences in flower constellations at the Moon versus at Earth. It is found that due to the longer rotation period of the Moon, the number of petals in the flower constellation must be quite large in order to produce reasonable orbit sizes. Two types of flower constellations are investigated: a single-petal and multi-petal constellation. The single-petal constellation consists of a string-of-pearls formation within one inertial flower constellation orbit. The multi-petal configuration has one satellite per inertial orbit, with the orbits spaced symmetrically within a 360 degree RAAN distribution. Optimal methods for deployment are explored for both configurations. Phasing orbits are used to deploy the single-petal constellation. This is found to be a simple and low-cost deployment scheme. The multi-petal configuration requires larger plane change maneuvers, and three-burn transfer orbit solutions that are optimal over single impulsive burn maneuvers are found. The mothercraft maneuver into the long-term communications orbit is also investigated. This maneuver is once again just a phase orbit maneuver for the single-petal constellation and is low cost. A polar mothercraft orbit is desired for the multi-petal configuration, again requiring a large and expensive plane change maneuver. As was the case with the deployment maneuver, a three-burn transfer orbit series is found to be cost optimal over a series of impulsive burns for this maneuver. Finally, once the constellation is established, orbit maintenance maneuvers are calculated. A 4 kg cubesat with 1 kg of fuel is assumed, and various thruster types are used to correlate required maintenance Delta-Vs to propellant mass required. It is found that the flower constellations at the Moon can be maintained for between 100 and 800 days, depending on the eciency of the thruster system used. Ultimately, a small satellite constellation at the Moon is found to be feasible to establish and maintain for a science or communication mission.

Electric Propulsion System for Constellation Deployment and Orbit Control of Minisats

NASA Astrophysics Data System (ADS)

Bianco, P.; de Rocco, L.; Lovera, M.

1999-09-01

The late technology developments and the demand for low-cost space missions have raised the interest in small satellites and in their potential use as parts of satellite formations as well as building units of satellite constellations. Formation flying of small satellites can be used to bring in-orbit spares for failed payloads on larger satellites as well as to replace large satellites at all by flying the mission on more small satellites, each carrying a single payload. Small satellites can be used in constellations for scientific missions (e.g. remote sensing) as well as for commercial purposes (e.g. data relay). Yet, "small satellite" doesn't necessarily mean "cheap satellite": cost reduction must be enforced into the space mission design since the very beginning of it, at system level. This usually implies seeking for trade-offs on most expensive system items for a small sat. Among these, we surely have the launch and the onboard propulsion system for orbital manoeuvres and station keeping: the stricter the requirements, the higher the costs. And, when dealing with satellite constellations or formations, orbital requirements can be quite challenging. The system designer is faced with the dilemma on whether to buy a relatively expensive dedicated launch or to have a highly cost-impactive autonomous onboard propulsion system that should perform orbit transfers as well. The present paper, which is an up-to-date version of the one presented at IAF-99, introduces a system based on FEEP (Field Emission Electric Propulsion) technology, featuring low thrust plug-on propulsion units. Thanks to the self-contained concept of FEEP thrusters and to the plug-on feature of the whole system, a very low cost-impactive onboard propulsion system can be implemented in order to serve for both orbital manoeuvres (constellation / formation deployment, orbit rising) and orbit maintenance (drag compensation, station keeping relative to other satellites). Most convenient strategies to operate such propulsion systems with respect to orbital requirements, principal design drivers and sizing methods are presented and discussed as well as practical up-to-date case study results performed at Carlo Gavazzi Space.

Approach for Mitigating Pressure Garment Design Risks in a Mobile Lunar Surface Systems Architecture

NASA Technical Reports Server (NTRS)

Aitchison, Lindsay

2009-01-01

The stated goals of the 2004 Vision for Space Exploration focus on establishing a human presence throughout the solar system beginning with the establishment of a permanent human presence on the Moon. However, the precise objectives to be accomplished on the lunar surface and the optimal system architecture to achieve those objectives have been a topic of much debate since the inception of the Constellation Program. There are two basic styles of system architectures being traded at the Programmatic level: a traditional large outpost that would focus on techniques for survival off our home planet and a greater depth of exploration within one area, or a mobile approach- akin to a series of nomadic camps- that would allow greater breadth of exploration opportunities. The traditional outpost philosophy is well within the understood pressure garment design space with respect to developing interfaces and operational life cycle models. The mobile outpost, however, combines many unknowns with respect to pressure garment performance and reliability that could dramatically affect the cost and schedule risks associated with the Constellation space suit system. This paper provides an overview of the concepts being traded for a mobile architecture from the operations and hardware implementation perspective, describes the primary risks to the Constellation pressure garment associated with each of the concepts, and summarizes the approach necessary to quantify the pressure garment design risks to enable the Constellation Program to make informed decisions when deciding on an overall lunar surface systems architecture.

The Global Precipitation Measurement (GPM) Mission: Overview and U.S. Status

NASA Technical Reports Server (NTRS)

Hou, Arthur Y.; Azarbarzin, Ardeshir A.; Kakar, Ramesh K.; Neeck, Steven

2011-01-01

The Global Precipitation Measurement (GPM) Mission is an international satellite mission specifically designed to unify and advance precipitation measurements from a constellation of research and operational microwave sensors. Building upon the success of the U.S.-Japan Tropical Rainfall Measuring Mission (TRMM), the National Aeronautics and Space Administration (NASA) of the United States and the Japan Aerospace and Exploration Agency (JAXA) will deploy in 2013 a GPM "Core" satellite carrying a KulKa-band Dual-frequency Precipitation Radar (DPR) and a conical-scanning multi-channel (10-183 GHz) GPM Microwave Imager (GMI) to establish a new reference standard for precipitation measurements from space. The combined active/passive sensor measurements will also be used to provide common database for precipitation retrievals from constellation sensors. For global coverage, GPM relies on existing satellite programs and new mission opportunities from a consortium of partners through bilateral agreements with either NASA or JAXA. Each constellation member may have its unique scientific or operational objectives but contributes microwave observations to GPM for the generation and dissemination of unified global precipitation data products. In addition to the DPR and GMI on the Core Observatory, the baseline GPM constellation consists of the following sensors: (1) Special Sensor Microwave Imager/Sounder (SSMIS) instruments on the U.S. Defense Meteorological Satellite Program (DMSP) satellites, (2) the Advanced Microwave Scanning Radiometer- 2 (AMSR-2) on the GCOM-Wl satellite of JAXA, (3) the Multi-Frequency Microwave Scanning Radiometer (MADRAS) and the multi-channel microwave humidity sounder (SAPHIR) on the French-Indian Megha-Tropiques satellite, (4) the Microwave Humidity Sounder (MHS) on the National Oceanic and Atmospheric Administration (NOAA)-19, (5) MHS instruments on MetOp satellites launched by the European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT), (6) the Advanced Technology Microwave Sounder (ATMS) on the National Polar-orbiting Operational Environmental Satellite System (NPOESS) Preparatory Project (NPP), (7) ATMS instruments on the NOAA-NASA Joint Polar Satellite System (JPSS) satellites, and (8) a microwave imager under planning for the Defense Weather Satellite System (DWSS).

Applying Advances in GPM Radiometer Intercalibration and Algorithm Development to a Long-Term TRMM/GPM Global Precipitation Dataset

NASA Astrophysics Data System (ADS)

Berg, W. K.

2016-12-01

The Global Precipitation Mission (GPM) Core Observatory, which was launched in February of 2014, provides a number of advances for satellite monitoring of precipitation including a dual-frequency radar, high frequency channels on the GPM Microwave Imager (GMI), and coverage over middle and high latitudes. The GPM concept, however, is about producing unified precipitation retrievals from a constellation of microwave radiometers to provide approximately 3-hourly global sampling. This involves intercalibration of the input brightness temperatures from the constellation radiometers, development of an apriori precipitation database using observations from the state-of-the-art GPM radiometer and radars, and accounting for sensor differences in the retrieval algorithm in a physically-consistent way. Efforts by the GPM inter-satellite calibration working group, or XCAL team, and the radiometer algorithm team to create unified precipitation retrievals from the GPM radiometer constellation were fully implemented into the current version 4 GPM precipitation products. These include precipitation estimates from a total of seven conical-scanning and six cross-track scanning radiometers as well as high spatial and temporal resolution global level 3 gridded products. Work is now underway to extend this unified constellation-based approach to the combined TRMM/GPM data record starting in late 1997. The goal is to create a long-term global precipitation dataset employing these state-of-the-art calibration and retrieval algorithm approaches. This new long-term global precipitation dataset will incorporate the physics provided by the combined GPM GMI and DPR sensors into the apriori database, extend prior TRMM constellation observations to high latitudes, and expand the available TRMM precipitation data to the full constellation of available conical and cross-track scanning radiometers. This combined TRMM/GPM precipitation data record will thus provide a high-quality high-temporal resolution global dataset for use in a wide variety of weather and climate research applications.

Exploration Life Support Technology Development for Lunar Missions

NASA Technical Reports Server (NTRS)

Ewert, Michael K.; Barta, Daniel J.; McQuillan, Jeffrey

2009-01-01

Exploration Life Support (ELS) is one of NASA's Exploration Technology Development Projects. ELS plans, coordinates and implements the development of new life support technologies for human exploration missions as outlined in NASA's Vision for Space Exploration. ELS technology development currently supports three major projects of the Constellation Program - the Orion Crew Exploration Vehicle (CEV), the Altair Lunar Lander and Lunar Surface Systems. ELS content includes Air Revitalization Systems (ARS), Water Recovery Systems (WRS), Waste Management Systems (WMS), Habitation Engineering, Systems Integration, Modeling and Analysis (SIMA), and Validation and Testing. The primary goal of the ELS project is to provide different technology options to Constellation which fill gaps or provide substantial improvements over the state-of-the-art in life support systems. Since the Constellation missions are so challenging, mass, power, and volume must be reduced from Space Shuttle and Space Station technologies. Systems engineering analysis also optimizes the overall architecture by considering all interfaces with the life support system and potential for reduction or reuse of resources. For long duration missions, technologies which aid in closure of air and water loops with increased reliability are essential as well as techniques to minimize or deal with waste. The ELS project utilizes in-house efforts at five NASA centers, aerospace industry contracts, Small Business Innovative Research contracts and other means to develop advanced life support technologies. Testing, analysis and reduced gravity flight experiments are also conducted at the NASA field centers. This paper gives a current status of technologies under development by ELS and relates them to the Constellation customers who will eventually use them.

Improving BeiDou precise orbit determination using observations of onboard MEO satellite receivers

NASA Astrophysics Data System (ADS)

Ge, Haibo; Li, Bofeng; Ge, Maorong; Shen, Yunzhong; Schuh, Harald

2017-12-01

In recent years, the precise orbit determination (POD) of the regional Chinese BeiDou Navigation Satellite System (BDS) has been a hot spot because of its special constellation consisting of five geostationary earth orbit (GEO) satellites and five inclined geosynchronous satellite orbit (IGSO) satellites besides four medium earth orbit (MEO) satellites since the end of 2012. GEO and IGSO satellites play an important role in regional BDS applications. However, this brings a great challenge to the POD, especially for the GEO satellites due to their geostationary orbiting. Though a number of studies have been carried out to improve the POD performance of GEO satellites, the result is still much worse than that of IGSO and MEO, particularly in the along-track direction. The major reason is that the geostationary characteristic of a GEO satellite results in a bad geometry with respect to the ground tracking network. In order to improve the tracking geometry of the GEO satellites, a possible strategy is to mount global navigation satellite system (GNSS) receivers on MEO satellites to collect the signals from GEO/IGSO GNSS satellites so as that these observations can be used to improve GEO/IGSO POD. We extended our POD software package to simulate all the related observations and to assimilate the MEO-onboard GNSS observations in orbit determination. Based on GPS and BDS constellations, simulated studies are undertaken for various tracking scenarios. The impact of the onboard GNSS observations is investigated carefully and presented in detail. The results show that MEO-onboard observations can significantly improve the orbit precision of GEO satellites from metres to decimetres, especially in the along-track direction. The POD results of IGSO satellites also benefit from the MEO-onboard data and the precision can be improved by more than 50% in 3D direction.

Retrieval of spatially distributed hydrological properties from satellite observations for spatial evaluation of a national water resources model.

NASA Astrophysics Data System (ADS)

Mendiguren González, G.; Stisen, S.; Koch, J.

2016-12-01

The NASA Cyclone Global Navigation Satellite System (CYNSS) mission provides high temporal resolution observations of cyclones from a constellation of eight low-Earth orbiting satellites. Using the relatively new technique of Global Navigation Satellite System reflectometry (GNSS-R), all-weather observations are possible, penetrating even deep convection within hurricane eye walls. The compact nature of the GNSS-R receivers permits the use of small satellites, which in turn enables the launch of a constellation of satellites from a single launch vehicle. Launched in December of 2016, the eight CYGNSS satellites provide 25 km resolution observations of mean square slope (surface roughness) and surface winds with a 2.8 hour median revisit time from 38 S to 38 N degrees latitude. In addition to the calibration and validation of CYGNSS sea state observations, the CYGNSS science team is assessing the ability of the mission to provide estimates of cyclone size, intensity, and integrated kinetic energy. With its all-weather ability and high temporal resolution, the CYGNSS mission will add significantly to our ability to monitor cyclone genesis and intensification and will significantly reduce uncertainties in our ability to estimate cyclone intensity, a key variable in predicting its destructive potential. Members of the CYGNSS Science Team are also assessing the assimilation of CYGNSS data into hurricane forecast models to determine the impact of the data on forecast skill, using the data to study extra-tropical cyclones, and looking at connections between tropical cyclones and global scale weather, including the global hydrologic cycle. This presentation will focus on the assessment of early on-orbit observations of cyclones with respect to these various applications.

KSC-2009-1997

NASA Image and Video Library

2009-03-09

CAPE CANAVERAL, Fla. – Near Launch Pad 39B at NASA's Kennedy Space Center in Florida, Jose Perez-Morales explains use of the launch pad for the Ares rockets in the Constellation Program. Perez-Morales is Constellation senior pad project manager. Pad 39B will be used for the Ares I-X flight test, targeted for July 2009. The I-X flight will provide NASA an early opportunity to test and prove hardware, facilities and ground operations associated with Ares I, part of the Constellation Program to return men to the moon and beyond. Ares I is the essential core of a safe, reliable, cost-effective space transportation system that eventually will carry crewed missions back to the moon, on to Mars and out into the solar system. Photo credit: NASA/Jack Pfaller

Galileo: The Added Value for Integrity in Harsh Environments.

PubMed

Borio, Daniele; Gioia, Ciro

2016-01-16

A global navigation satellite system (GNSS)-based navigation is a challenging task in a signal-degraded environments where GNSS signals are distorted by multipath and attenuated by fading effects: the navigation solution may be inaccurate or unavailable. A possible approach to improve accuracy and availability is the joint use of measurements from different GNSSs and quality check algorithms; this approach is investigated here using live GPS and Galileo signals. A modified receiver autonomous integrity monitoring (RAIM) algorithm, including geometry and separability checks, is proposed to detect and exclude erroneous measurements: the multi-constellation approach provides redundant measurements, and RAIM exploits them to exclude distorted observations. The synergy between combined GPS/Galileo navigation and RAIM is analyzed using live data; the performance is compared to the accuracy and availability of a GPS-only solution. The tests performed demonstrate that the methods developed are effective techniques for GNSS-based navigation in signal-degraded environments. The joint use of the multi-constellation approach and of modified RAIM algorithms improves the performance of the navigation system in terms of both accuracy and availability.

Galileo: The Added Value for Integrity in Harsh Environments

PubMed Central

Borio, Daniele; Gioia, Ciro

2016-01-01

A global navigation satellite system (GNSS)-based navigation is a challenging task in a signal-degraded environments where GNSS signals are distorted by multipath and attenuated by fading effects: the navigation solution may be inaccurate or unavailable. A possible approach to improve accuracy and availability is the joint use of measurements from different GNSSs and quality check algorithms; this approach is investigated here using live GPS and Galileo signals. A modified receiver autonomous integrity monitoring (RAIM) algorithm, including geometry and separability checks, is proposed to detect and exclude erroneous measurements: the multi-constellation approach provides redundant measurements, and RAIM exploits them to exclude distorted observations. The synergy between combined GPS/Galileo navigation and RAIM is analyzed using live data; the performance is compared to the accuracy and availability of a GPS-only solution. The tests performed demonstrate that the methods developed are effective techniques for GNSS-based navigation in signal-degraded environments. The joint use of the multi-constellation approach and of modified RAIM algorithms improves the performance of the navigation system in terms of both accuracy and availability. PMID:26784205

Statistical physics inspired energy-efficient coded-modulation for optical communications.

PubMed

Djordjevic, Ivan B; Xu, Lei; Wang, Ting

2012-04-15

Because Shannon's entropy can be obtained by Stirling's approximation of thermodynamics entropy, the statistical physics energy minimization methods are directly applicable to the signal constellation design. We demonstrate that statistical physics inspired energy-efficient (EE) signal constellation designs, in combination with large-girth low-density parity-check (LDPC) codes, significantly outperform conventional LDPC-coded polarization-division multiplexed quadrature amplitude modulation schemes. We also describe an EE signal constellation design algorithm. Finally, we propose the discrete-time implementation of D-dimensional transceiver and corresponding EE polarization-division multiplexed system. © 2012 Optical Society of America

Temporal Experiment for Storms and Tropical Systems Technology Demonstration (TEMPEST-D): Risk Reduction for 6U-Class Nanosatellite Constellations

NASA Astrophysics Data System (ADS)

Reising, Steven C.; Gaier, Todd C.; Kummerow, Christian D.; Padmanabhan, Sharmila; Lim, Boon H.; Brown, Shannon T.; Heneghan, Cate; Chandra, Chandrasekar V.; Olson, Jon; Berg, Wesley

2016-04-01

TEMPEST-D will reduce the risk, cost and development time of a future constellation of 6U-Class nanosatellites to directly observe the time evolution of clouds and study the conditions that control the transition from non-precipitating to precipitating clouds using high-temporal resolution observations. TEMPEST-D provides passive millimeter-wave observations using a compact instrument that fits well within the size, weight and power (SWaP) requirements of the 6U-Class satellite architecture. TEMPEST-D is suitable for launch through NASA's CubeSat Launch Initiative (CSLI), for which it was selected in February 2015. By measuring the temporal evolution of clouds from the moment of the onset of precipitation, a TEMPEST constellation mission would improve our understanding of cloud processes and help to constrain one of the largest sources of uncertainty in climate models. Knowledge of clouds, cloud processes and precipitation is essential to our understanding of climate change. Uncertainties in the representation of key processes that govern the formation and dissipation of clouds and, in turn, control the global water and energy budgets lead to substantially different predictions of future climate in current models. TEMPEST millimeter-wave radiometers with five frequencies from 89 GHz to 182 GHz penetrate into the cloud to observe key changes as precipitation begins or ice accumulates inside the storm. The evolution of ice formation in clouds is important for climate prediction and a key factor in Earth's radiation budget. TEMPEST is designed to provide critical information on the time evolution of cloud and precipitation, yielding a first-order understanding of assumptions and uncertainties in current cloud parameterizations in general circulation models in diverse climate regimes. For a potential future one-year operational mission, five identical 6U-Class satellites would be deployed in the same orbital plane with 5- to 10-minute spacing deployed in an orbit similar to the International Space Station resupply missions, i.e. at ~400 km altitude and ~51° inclination. A one-year mission would capture 3 million observations of precipitation greater than 1 mm/hour rain rate, including at least 100,000 deep convective events. Passive drag-adjusting maneuvers would separate the five CubeSats in the same orbital plane by 5-10 minutes each, similar to deployment techniques to be used by NASA's Cyclone Global Navigation Satellite Systems (CYGNSS) mission.

NASA's Earth Observing System (EOS): Delivering on the Dream, Today and Tomorrow

NASA Technical Reports Server (NTRS)

Kelly, Angelita C.; Johnson, Patricia; Case, Warren F.

2010-01-01

This paper describes the successful operations of NASA's Earth Observing System (EOS) satellites over the past 10 years and the plans for the future. Excellent operations performance has been a key factor in the overall success of EOS. The EOS Program was conceived in the 1980s and began to take shape in the early 1990s. EOS consists of a series of satellites that study the Earth as an interrelated system. It began with the launch of Terra in December 1999, followed by Aqua in May 2002, and Aura in July 2004. A key EOS goal is to provide a long-term continuous data set to enable the science community to develop a better understanding of land, ocean, and atmospheric processes and their interactions. EOS has produced unprecedented amounts of data which are used all over the world free of charge. Mission operations have resulted in data recovery for Terra, Aqua, and Aura that have consistently exceeded mission requirements. The paper describes the ground systems and organizations that control the EOS satellites, capture the raw data, and distribute the processed science data sets. The paper further describes how operations have evolved since 1999. Examples of this evolution include (a) the implementation of new mission safety requirements for orbital debris monitoring; (b) technology upgrades to keep facilities at the state of the art; (c) enhancements to meet changing security requirements; and (d) operations management of the 2 international Earth Observing Constellations of 11 satellites known as the "Morning Constellation" and the "A-Train". The paper concludes with a view into the future based on the latest spacecraft status, lifetime projections, and mission plans.

Analysis of a Constellation Lab Cooperative Learning Activity

NASA Astrophysics Data System (ADS)

Gauthier, A. J.

2001-12-01

A cooperative learning activity was designed for use in the undergraduate laboratory course Introduction to Astronomical Observation. This group exercise enhances the student's learning of constellations and will hopefully increase retention of the material throughout the semester. It also serves as an "ice-breaker" during the first week of lab, promoting student involvement and vested interest in the course. To gain some insight into the student mind, a survey was conducted to evaluate the usefulness and overall opinion of this method. The students who completed the survey had previously been enrolled in a pre-requisite astronomy course that also required a constellation lab. In this previous course they "learned" the constellations from an instructor and a flashlight beam, studied them on their own, and then promptly took a quiz. Both methods are analyzed from an instructional designer's point of view and suggestions for future activities are presented. The preliminary results and accompanying activity will be discussed in poster and hand-out medium.

RaInCube: a proposed constellation of precipitation profiling Radars In Cubesat

NASA Astrophysics Data System (ADS)

Peral, E.; Tanelli, S.; Haddad, Z. S.; Stephens, G. L.; Im, E.

2014-12-01

Precipitation radars in Low-Earth-Orbit provide vertically resolved profiles of rain and snow on a global scale. With the recent advances in miniaturized radar and CubeSat/SmallSat technologies, it would now be feasible to launch multiple copies of the same radar instrument in desirable formations to allow measurements of short time scale evolution of atmospheric processes. One such concept is the novel radar architecture compatible with the 6U CubeSat class that is being developed at JPL by exploiting simplification and miniaturization of the radar subsystems. The RaInCube architecture would significantly reduce the number of components, power consumption and mass with respect to existing spaceborne radars. The baseline RaInCube instrument configuration would be a fixed nadir-pointing profiler at Ka-band with a minimum detectable reflectivity better than +10 dBZ at 250m range resolution and 5 km horizontal resolution. The low cost nature of the RaInCube platform would enable deployment of a constellation of identical copies of the same instrument in various relative positions in LEO to address specific observational gaps left open by the current missions that require high-resolution vertical profiling capability. A constellation of only four RaInCubes would populate the precipitation statistics in a distributed fashion across the globe and across the times of day, and therefore, would enable substantially better sampling of the diurnal cycle statistics. One could extend this scheme by adding more RaInCubes in each of the orbital planes, and phase them once in orbit so that they would be separated by an arbitrary amount of time among them. Wide separations (say 20-30 min) would further extend the sampling of the diurnal cycle to sub-hourly scales. Narrower time separations between RaInCubes would allow studying the evolution of convective systems at the convective time scale in each region of interest and would reveal the dominant modes of evolution of each corresponding climatological regime. A constellation of RaInCubes would also be a natural complement to other resources aiming at monitoring the evolution of weather systems, for example the Geostationary IR/VIS imagers, the NEXRAD network, and the GPM constellation.

Error Reduction Analysis and Optimization of Varying GRACE-Type Micro-Satellite Constellations

NASA Astrophysics Data System (ADS)

Widner, M. V., IV; Bettadpur, S. V.; Wang, F.; Yunck, T. P.

2017-12-01

The Gravity Recovery and Climate Experiment (GRACE) mission has been a principal contributor in the study and quantification of Earth's time-varying gravity field. Both GRACE and its successor, GRACE Follow-On, are limited by their paired satellite design which only provide a full map of Earth's gravity field approximately every thirty days and at large spatial resolutions of over 300 km. Micro-satellite technology has presented the feasibility of improving the architecture of future missions to address these issues with the implementation of a constellations of satellites having similar characteristics as GRACE. To optimize the constellation's architecture, several scenarios are evaluated to determine how implementing this configuration affects the resultant gravity field maps and characterize which instrument system errors improve, which do not, and how changes in constellation architecture affect these errors.

Ionospheric Simulation System for Satellite Observations and Global Assimilative Model Experiments - ISOGAME

NASA Technical Reports Server (NTRS)

Pi, Xiaoqing; Mannucci, Anthony J.; Verkhoglyadova, Olga; Stephens, Philip; Iijima, Bryron A.

2013-01-01

Modeling and imaging the Earth's ionosphere as well as understanding its structures, inhomogeneities, and disturbances is a key part of NASA's Heliophysics Directorate science roadmap. This invention provides a design tool for scientific missions focused on the ionosphere. It is a scientifically important and technologically challenging task to assess the impact of a new observation system quantitatively on our capability of imaging and modeling the ionosphere. This question is often raised whenever a new satellite system is proposed, a new type of data is emerging, or a new modeling technique is developed. The proposed constellation would be part of a new observation system with more low-Earth orbiters tracking more radio occultation signals broadcast by Global Navigation Satellite System (GNSS) than those offered by the current GPS and COSMIC observation system. A simulation system was developed to fulfill this task. The system is composed of a suite of software that combines the Global Assimilative Ionospheric Model (GAIM) including first-principles and empirical ionospheric models, a multiple- dipole geomagnetic field model, data assimilation modules, observation simulator, visualization software, and orbit design, simulation, and optimization software.

Science Opportunities Enabled by NASA's Constellation System: Interim Report

NASA Technical Reports Server (NTRS)

2008-01-01

In 2004 NASA initiated studies of advanced science mission concepts known as the Vision Missions and inspired by a series of NASA roadmap activities conducted in 2003. Also in 2004 NASA began implementation of the first phases of a new space exploration policy, the Vision for Space Exploration. This implementation effort included development of a new human-carrying spacecraft, known as Orion, and two new launch vehicles, the Ares I and Ares V rockets.collectively called the Constellation System. NASA asked the National Research Council (NRC) to evaluate the science opportunities enabled by the Constellation System (see Preface) and to produce an interim report on a short time schedule and a final report by November 2008. The committee notes, however, that the Constellation System and its Orion and Ares vehicles have been justified by NASA and selected in order to enable human exploration beyond low Earth orbit, and not to enable science missions. This interim report of the Committee on Science Opportunities Enabled by NASA s Constellation System evaluates the 11 Vision Mission studies presented to it and groups them into two categories: those more deserving of future study, and those less deserving of future study. Although its statement of task also refers to Earth science missions, the committee points out that the Vision Missions effort was focused on future astronomy, heliophysics, and planetary exploration and did not include any Earth science studies because, at the time, the NRC was conducting the first Earth science decadal survey, and funding Earth science studies as part of the Vision Missions effort would have interfered with that process. Consequently, no Earth science missions are evaluated in this interim report. However, the committee will evaluate any Earth science mission proposal submitted in response to its request for information issued in March 2008 (see Appendix A). The committee based its evaluation of the preexisting Vision Missions studies on two criteria: whether the concepts offered the potential for a significant scientific advance, and whether or not the concepts would benefit from the Constellation System. The committee determined that all of the concepts offered the possibility of a significant scientific advance, but it cautions that such an evaluation ultimately must be made by the decadal survey process, and it emphasizes that this interim report s evaluation should not be considered to be an endorsement of the scientific merit of these proposals, which must of course be evaluated relative to other proposals. The committee determined that seven of these concepts would benefit from the Constellation System, whereas four would not, but it stresses that this conclusion does not reflect an evaluation of the scientific merit of the projects, but rather an assessment of whether or not new capabilities provided by the Constellation System could significantly affect them. Some of the mission concepts, such as the Advanced Compton Telescope, already offer a significant scientific advance and fit easily within the mass and volume constraints of existing launch vehicles. Other mission concepts, such as the Palmer Quest proposal to drill through the Mars polar cap, are not constrained by the launch vehicle, but rather by other technology limitations. The committee evaluated the mission concepts as presented to it, aware nevertheless that proposing a far larger and more ambitious mission with the same science goals might be possible given the capabilities of the Ares V launch vehicle. (Such proposals can be submitted in response to the committee s request for information to be evaluated in its final report.) See Table S.1 for a summary of the Vision Missions, including their cost estimates, technical maturity, and reasons that they might benefit from the Constellation System. The committee developed several findings and recommendations.

Constellation Program (CxP) Crew Exploration Vehicle (CEV) Parachute Assembly System (CPAS) Independent Design Reliability Assessment. Volume 2; Appendices

NASA Technical Reports Server (NTRS)

Kelly, Michael J.

2010-01-01

This document contains the Appendices to the report documenting the activities, findings, and NASA Engineering and Safety Center (NESC) recommendations of a multidiscipline team to independently assess the Constellation Program (CxP) Crew Exploration Vehicle (CEV) Parachute Assembly System (CPAS). The assessment occurred during a period of 15 noncontiguous months between December 2008 and April 2010, prior to the CPAS Project's Preliminary Design Review (PDR) in August 2010.

Evidence of Ubiquitous Large-Amplitude Alfven waves in the Global Field-Aligned Current System

NASA Astrophysics Data System (ADS)

Pakhotin, I.; Mann, I.; Lysak, R. L.; Knudsen, D. J.; Burchill, J. K.; Gjerloev, J. W.; Rae, J.; Forsyth, C.; Murphy, K. R.; Miles, D.; Ozeke, L.; Balasis, G.

2017-12-01

Large-amplitude non-stationarities have been observed during an analysis of a quiescent field-aligned current system crossing using the multi-satellite Swarm constellation. Using simultaneous electric and magnetic field measurements it has been determined that these non-stationarities, reaching tens to hundreds of nanoteslas, are Alfvenic in nature. Evidence suggests that these large-amplitude Alfven waves are a ubiquitous, fundamentally inherent feature of and exist in a continuum with larger-scale field-aligned currents, and both can be explained using the same physical paradigm of reflected Alfven waves.

Streamlining the Design Tradespace for Earth Imaging Constellations

NASA Technical Reports Server (NTRS)

Nag, Sreeja; Hughes, Steven P.; Le Moigne, Jacqueline J.

2016-01-01

Satellite constellations and Distributed Spacecraft Mission (DSM) architectures offer unique benefits to Earth observation scientists and unique challenges to cost estimators. The Cost and Risk (CR) module of the Tradespace Analysis Tool for Constellations (TAT-C) being developed by NASA Goddard seeks to address some of these challenges by providing a new approach to cost modeling, which aggregates existing Cost Estimating Relationships (CER) from respected sources, cost estimating best practices, and data from existing and proposed satellite designs. Cost estimation through this tool is approached from two perspectives: parametric cost estimating relationships and analogous cost estimation techniques. The dual approach utilized within the TAT-C CR module is intended to address prevailing concerns regarding early design stage cost estimates, and offer increased transparency and fidelity by offering two preliminary perspectives on mission cost. This work outlines the existing cost model, details assumptions built into the model, and explains what measures have been taken to address the particular challenges of constellation cost estimating. The risk estimation portion of the TAT-C CR module is still in development and will be presented in future work. The cost estimate produced by the CR module is not intended to be an exact mission valuation, but rather a comparative tool to assist in the exploration of the constellation design tradespace. Previous work has noted that estimating the cost of satellite constellations is difficult given that no comprehensive model for constellation cost estimation has yet been developed, and as such, quantitative assessment of multiple spacecraft missions has many remaining areas of uncertainty. By incorporating well-established CERs with preliminary approaches to approaching these uncertainties, the CR module offers more complete approach to constellation costing than has previously been available to mission architects or Earth scientists seeking to leverage the capabilities of multiple spacecraft working in support of a common goal.

Contribution of Multi-GNSS Constellation to SLR-Derived Terrestrial Reference Frame

NASA Astrophysics Data System (ADS)

Sośnica, K.; Bury, G.; Zajdel, R.

2018-03-01

All satellites of new Global Navigation Satellite Systems (GNSS) are equipped with laser retroreflectors dedicated to Satellite Laser Ranging (SLR). This paper demonstrates the contribution of SLR tracking of multi-GNSS constellations to the improved SLR-derived reference frame and scientific products. We show a solution strategy with estimating satellite orbits, SLR station coordinates, geocenter coordinates, and Earth rotation parameters using SLR observations to 2 Laser Geodynamics Satellites (LAGEOS) and 55 GNSS satellites: 1 GPS, 31 Globalnaya Navigatsionnaya Sputnikovaya Sistema, 18 Galileo, 3 BeiDou Inclined Geosynchronous Orbit, 1 BeiDou Medium Earth Orbit, and 1 Quasi-Zenith Satellite System satellite for the period 2014.0-2017.4. Due to a substantial number of GNSS observations, the number of weekly solutions for some SLR stations, for example, Arkhyz, Komsomolsk, Altay, and Brasilia, is larger up to 41% in the combined LAGEOS + GNSS solution when compared to the LAGEOS-only solution. The SLR observations to GNSS can transfer the orientation of the reference frame from GNSS to SLR solutions. As a result, the SLR-derived pole coordinates and length-of-day estimates become more consistent with GNSS microwave-based results. The root-mean-square errors of length-of-day are reduced from 122.5 μs/d to 43.0 μs/d, whereas mean offsets are reduced from -81.6 μs/d to 0.5 μs/d in LAGEOS only and in the combined LAGEOS + GNSS solutions, respectively.

Observing the Anthropocene from Space

NASA Astrophysics Data System (ADS)

Dittus, Hansjörg

2016-07-01

Influence of mankind on Earth's climate is evident. The growing population using the resources available, especially by burning goal, oil and gas, changes the composition of the Earth's atmosphere with the result of a continuously increasing temperature. Effects are not limited to the regional scale but are evident on the whole planet, meanwhile named Anthropocene. According to this global influence, it's necessary to also extend monitoring to the entire planet. Space-based observation systems are not limited by any artificial borders and are in principle able, to cover the whole Earth. In principle, two different ways of observation can be selected: Either a dedicated spacecraft will be send into low earth orbit (LEO) or existing platforms are used. Advantages of satellites are the more or less freely selectable orbit (with orbits covering also the polar regions) and the possible adaption of spacecraft platform for the dedicated instrument. On the other hand platforms like the ISS space station enable continuous long term coverage with different instruments. The drawback of an only limited coverage based on the orbit inclination is made up by the possibility to service systems on the station. Furthermore different generations of sensors can be run in parallel and therefore cross calibrated if needed. This paper reviews the currently available sensors types and discusses potential future needs. Included in this discussion is the international space station as an already available platform for earth observation. Furthermore, discussion should also take into account, that an increasing number of constellations with dozens or even thousand satellites are planned. Are these constellations also an option for an increased temporal and spatial monitoring of the Earth?

Commanding Constellations (Pipeline Architecture)

NASA Technical Reports Server (NTRS)

Ray, Tim; Condron, Jeff

2003-01-01

Providing ground command software for constellations of spacecraft is a challenging problem. Reliable command delivery requires a feedback loop; for a constellation there will likely be an independent feedback loop for each constellation member. Each command must be sent via the proper Ground Station, which may change from one contact to the next (and may be different for different members). Dynamic configuration of the ground command software is usually required (e.g. directives to configure each member's feedback loop and assign the appropriate Ground Station). For testing purposes, there must be a way to insert command data at any level in the protocol stack. The Pipeline architecture described in this paper can support all these capabilities with a sequence of software modules (the pipeline), and a single self-identifying message format (for all types of command data and configuration directives). The Pipeline architecture is quite simple, yet it can solve some complex problems. The resulting solutions are conceptually simple, and therefore, reliable. They are also modular, and therefore, easy to distribute and extend. We first used the Pipeline architecture to design a CCSDS (Consultative Committee for Space Data Systems) Ground Telecommand system (to command one spacecraft at a time with a fixed Ground Station interface). This pipeline was later extended to include gateways to any of several Ground Stations. The resulting pipeline was then extended to handle a small constellation of spacecraft. The use of the Pipeline architecture allowed us to easily handle the increasing complexity. This paper will describe the Pipeline architecture, show how it was used to solve each of the above commanding situations, and how it can easily be extended to handle larger constellations.

The Evolution of a Long-Lived Mesoscale Convective System Observed by GLM

NASA Astrophysics Data System (ADS)

Peterson, M. J.; Rudlosky, S. D.; Antunes, L.

2017-12-01

Continuous Geostationary Lightning Mapper (GLM) observations are used to document total lightning activity over the life cycle of a long-lived Mesoscale Convective System (MCS). MCS's may be few in number, but they are important for the Global Electric Circuit (GEC) because they sustain high lightning flash rates and quasi steady state conduction currents (Wilson currents) over longer time periods than ordinary isolated convection. The optical characteristics of the flashes produced by MCS's change over time, providing additional insights into the precipitation structure, convective mode, and evolution of the storm system. These insights are particularly useful in areas void of radar observations. Intercalibrated passive microwave radiometer data from the Global Precipitation Measurement (GPM) constellation also are used to estimate changes in Wilson current generation as the system evolves. These results highlight the role of MCS's in the GEC, and showcase how optical flash descriptors relate to thunderstorm organization, maturity, and structure.

Participants' Experiences in Hellinger's Family Constellation Work: A Grounded Theory Study

ERIC Educational Resources Information Center

Georgiadou, Sofia

2012-01-01

As a recently introduced to the U.S. model of intergenerational systemic therapy from Germany, Bert Hellinger's Family Constellation Work (FCW) has very limited research support. Hellinger himself has authored a number of publications referencing hundreds of cases, where he implemented his method to approach a broad array of physical,…

Precise Point Positioning Using Triple GNSS Constellations in Various Modes

PubMed Central

Afifi, Akram; El-Rabbany, Ahmed

2016-01-01

This paper introduces a new dual-frequency precise point positioning (PPP) model, which combines the observations from three different global navigation satellite system (GNSS) constellations, namely GPS, Galileo, and BeiDou. Combining measurements from different GNSS systems introduces additional biases, including inter-system bias and hardware delays, which require rigorous modelling. Our model is based on the un-differenced and between-satellite single-difference (BSSD) linear combinations. BSSD linear combination cancels out some receiver-related biases, including receiver clock error and non-zero initial phase bias of the receiver oscillator. Forming the BSSD linear combination requires a reference satellite, which can be selected from any of the GPS, Galileo, and BeiDou systems. In this paper three BSSD scenarios are tested; each considers a reference satellite from a different GNSS constellation. Natural Resources Canada’s GPSPace PPP software is modified to enable a combined GPS, Galileo, and BeiDou PPP solution and to handle the newly introduced biases. A total of four data sets collected at four different IGS stations are processed to verify the developed PPP model. Precise satellite orbit and clock products from the International GNSS Service Multi-GNSS Experiment (IGS-MGEX) network are used to correct the GPS, Galileo, and BeiDou measurements in the post-processing PPP mode. A real-time PPP solution is also obtained, which is referred to as RT-PPP in the sequel, through the use of the IGS real-time service (RTS) for satellite orbit and clock corrections. However, only GPS and Galileo observations are used for the RT-PPP solution, as the RTS-IGS satellite products are not presently available for BeiDou system. All post-processed and real-time PPP solutions are compared with the traditional un-differenced GPS-only counterparts. It is shown that combining the GPS, Galileo, and BeiDou observations in the post-processing mode improves the PPP convergence time by 25% compared with the GPS-only counterpart, regardless of the linear combination used. The use of BSSD linear combination improves the precision of the estimated positioning parameters by about 25% in comparison with the GPS-only PPP solution. Additionally, the solution convergence time is reduced to 10 minutes for the BSSD model, which represents about 50% reduction, in comparison with the GPS-only PPP solution. The GNSS RT-PPP solution, on the other hand, shows a similar convergence time and precision to the GPS-only counterpart. PMID:27240376

Precise Point Positioning Using Triple GNSS Constellations in Various Modes.

PubMed

Afifi, Akram; El-Rabbany, Ahmed

2016-05-28

This paper introduces a new dual-frequency precise point positioning (PPP) model, which combines the observations from three different global navigation satellite system (GNSS) constellations, namely GPS, Galileo, and BeiDou. Combining measurements from different GNSS systems introduces additional biases, including inter-system bias and hardware delays, which require rigorous modelling. Our model is based on the un-differenced and between-satellite single-difference (BSSD) linear combinations. BSSD linear combination cancels out some receiver-related biases, including receiver clock error and non-zero initial phase bias of the receiver oscillator. Forming the BSSD linear combination requires a reference satellite, which can be selected from any of the GPS, Galileo, and BeiDou systems. In this paper three BSSD scenarios are tested; each considers a reference satellite from a different GNSS constellation. Natural Resources Canada's GPSPace PPP software is modified to enable a combined GPS, Galileo, and BeiDou PPP solution and to handle the newly introduced biases. A total of four data sets collected at four different IGS stations are processed to verify the developed PPP model. Precise satellite orbit and clock products from the International GNSS Service Multi-GNSS Experiment (IGS-MGEX) network are used to correct the GPS, Galileo, and BeiDou measurements in the post-processing PPP mode. A real-time PPP solution is also obtained, which is referred to as RT-PPP in the sequel, through the use of the IGS real-time service (RTS) for satellite orbit and clock corrections. However, only GPS and Galileo observations are used for the RT-PPP solution, as the RTS-IGS satellite products are not presently available for BeiDou system. All post-processed and real-time PPP solutions are compared with the traditional un-differenced GPS-only counterparts. It is shown that combining the GPS, Galileo, and BeiDou observations in the post-processing mode improves the PPP convergence time by 25% compared with the GPS-only counterpart, regardless of the linear combination used. The use of BSSD linear combination improves the precision of the estimated positioning parameters by about 25% in comparison with the GPS-only PPP solution. Additionally, the solution convergence time is reduced to 10 minutes for the BSSD model, which represents about 50% reduction, in comparison with the GPS-only PPP solution. The GNSS RT-PPP solution, on the other hand, shows a similar convergence time and precision to the GPS-only counterpart.

Towards an integrated strategy for monitoring wetland inundation with virtual constellations of optical and radar satellites

NASA Astrophysics Data System (ADS)

DeVries, B.; Huang, W.; Huang, C.; Jones, J. W.; Lang, M. W.; Creed, I. F.; Carroll, M.

2017-12-01

The function of wetlandscapes in hydrological and biogeochemical cycles is largely governed by surface inundation, with small wetlands that experience periodic inundation playing a disproportionately large role in these processes. However, the spatial distribution and temporal dynamics of inundation in these wetland systems are still poorly understood, resulting in large uncertainties in global water, carbon and greenhouse gas budgets. Satellite imagery provides synoptic and repeat views of the Earth's surface and presents opportunities to fill this knowledge gap. Despite the proliferation of Earth Observation satellite missions in the past decade, no single satellite sensor can simultaneously provide the spatial and temporal detail needed to adequately characterize inundation in small, dynamic wetland systems. Surface water data products must therefore integrate observations from multiple satellite sensors in order to address this objective, requiring the development of improved and coordinated algorithms to generate consistent estimates of surface inundation. We present a suite of algorithms designed to detect surface inundation in wetlands using data from a virtual constellation of optical and radar sensors comprising the Landsat and Sentinel missions (DeVries et al., 2017). Both optical and radar algorithms were able to detect inundation in wetlands without the need for external training data, allowing for high-efficiency monitoring of wetland inundation at large spatial and temporal scales. Applying these algorithms across a gradient of wetlands in North America, preliminary findings suggest that while these fully automated algorithms can detect wetland inundation at higher spatial and temporal resolutions than currently available surface water data products, limitations specific to the satellite sensors and their acquisition strategies are responsible for uncertainties in inundation estimates. Further research is needed to investigate strategies for integrating optical and radar data from virtual constellations, with a focus on reducing uncertainties, maximizing spatial and temporal detail, and establishing consistent records of wetland inundation over time. The findings and conclusions in this article do not necessarily represent the views of the U.S. Government.

Constellation Training Facility Support

NASA Technical Reports Server (NTRS)

Flores, Jose M.

2008-01-01

The National Aeronautics and Space Administration is developing the next set of vehicles that will take men back to the moon under the Constellation Program. The Constellation Training Facility (CxTF) is a project in development that will be used to train astronauts, instructors, and flight controllers on the operation of Constellation Program vehicles. It will also be used for procedure verification and validation of flight software and console tools. The CxTF will have simulations for the Crew Exploration Vehicle (CEV), Crew Module (CM), CEV Service Module (SM), Launch Abort System (LAS), Spacecraft Adapter (SA), Crew Launch Vehicle (CLV), Pressurized Cargo Variant CM, Pressurized Cargo Variant SM, Cargo Launch Vehicle, Earth Departure Stage (EDS), and the Lunar Surface Access Module (LSAM). The Facility will consist of part-task and full-task trainers, each with a specific set of mission training capabilities. Part task trainers will be used for focused training on a single vehicle system or set of related systems. Full task trainers will be used for training on complete vehicles and all of its subsystems. Support was provided in both software development and project planning areas of the CxTF project. Simulation software was developed for the hydraulic system of the Thrust Vector Control (TVC) of the ARES I launch vehicle. The TVC system is in charge of the actuation of the nozzle gimbals for navigation control of the upper stage of the ARES I rocket. Also, software was developed using C standards to send and receive data to and from hand controllers to be used in CxTF cockpit simulations. The hand controllers provided movement in all six rotational and translational axes. Under Project Planning & Control, support was provided to the development and maintenance of integrated schedules for both the Constellation Training Facility and Missions Operations Facilities Division. These schedules maintain communication between projects in different levels. The CxTF support provided is one that requires continuous maintenance since the project is still on initial development phases.

The solar wind-magnetosphere-ionosphere system

PubMed

Lyon

2000-06-16

The solar wind, magnetosphere, and ionosphere form a single system driven by the transfer of energy and momentum from the solar wind to the magnetosphere and ionosphere. Variations in the solar wind can lead to disruptions of space- and ground-based systems caused by enhanced currents flowing into the ionosphere and increased radiation in the near-Earth environment. The coupling between the solar wind and the magnetosphere is mediated and controlled by the magnetic field in the solar wind through the process of magnetic reconnection. Understanding of the global behavior of this system has improved markedly in the recent past from coordinated observations with a constellation of satellite and ground instruments.

The design and networking of dynamic satellite constellations for global mobile communication systems

NASA Technical Reports Server (NTRS)

Cullen, Cionaith J.; Benedicto, Xavier; Tafazolli, Rahim; Evans, Barry

1993-01-01

Various design factors for mobile satellite systems, whose aim is to provide worldwide voice and data communications to users with hand-held terminals, are examined. Two network segments are identified - the ground segment (GS) and the space segment (SS) - and are seen to be highly dependent on each other. The overall architecture must therefore be adapted to both of these segments, rather than each being optimized according to its own criteria. Terrestrial networks are grouped and called the terrestrial segment (TS). In the SS, of fundamental importance is the constellation altitude. The effect of the altitude on decisions such as constellation design choice and on network aspects like call handover statistics are fundamental. Orbit resonance is introduced and referred to throughout. It is specifically examined for its useful properties relating to GS/SS connectivities.

Temporal Experiment for Storms and Tropical Systems Technology Demonstration (TEMPEST-D): Risk Reduction for 6U-Class Nanosatellite Constellations

NASA Astrophysics Data System (ADS)

Reising, S. C.; Todd, G.; Kummerow, C. D.; Chandrasekar, V.; Padmanabhan, S.; Lim, B.; Brown, S. T.; van den Heever, S. C.; L'Ecuyer, T.; Ruf, C. S.; Luo, Z. J.; Munchak, S. J.; Haddad, Z. S.; Boukabara, S. A.

2015-12-01

The Temporal Experiment for Storms and Tropical Systems Technology Demonstration (TEMPEST-D) is designed to demonstrate required technology to enable a constellation of 6U-Class nanosatellites to directly observe the time evolution of clouds and study the conditions that control the transition of clouds to precipitation using high-temporal resolution observations. TEMPEST millimeter-wave radiometers in the 90-GHz to 183-GHz frequency range penetrate into the cloud to observe key changes as the cloud begins to precipitate or ice accumulates inside the storm. The evolution of ice formation in clouds is important for climate prediction since it largely drives Earth's radiation budget. TEMPEST improves understanding of cloud processes and helps to constrain one of the largest sources of uncertainty in climate models. TEMPEST-D provides observations at five millimeter-wave frequencies from 90 to 183 GHz using a single compact instrument that is well suited for the 6U-Class architecture and fits well within the capabilities of NASA's CubeSat Launch Initiative (CSLI), for which TEMPEST-D was approved in 2015. For a potential future mission of one year of operations, five identical 6U-Class satellites deployed in the same orbital plane with 5-10 minute spacing at ~400 km altitude and 50°-65° inclination are expected to capture 3 million observations of precipitation, including 100,000 deep convective events. TEMPEST is designed to provide critical information on the time evolution of cloud and precipitation microphysics, yielding a first-order understanding of the behavior of assumptions in current cloud-model parameterizations in diverse climate regimes.

ISHM Implementation for Constellation Systems

NASA Technical Reports Server (NTRS)

Figueroa, Fernando; Holland, Randy; Schmalzel, John; Duncavage, Dan; Crocker, Alan; Alena, Rick

2006-01-01

Integrated System Health Management (ISHM) is a capability that focuses on determining the condition (health) of every element in a complex System (detect anomalies, diagnose causes, prognosis of future anomalies), and provide data, information, and knowledge (DIaK) "not just data" to control systems for safe and effective operation. This capability is currently done by large teams of people, primarily from ground, but needs to be embedded on-board systems to a higher degree to enable NASA's new Exploration Mission (long term travel and stay in space), while increasing safety and decreasing life cycle costs of systems (vehicles; platforms; bases or outposts; and ground test, launch, and processing operations). This viewgraph presentation reviews the use of ISHM for the Constellation system.

Welcome to NASA's Earth Science Enterprise. Version 3

NASA Technical Reports Server (NTRS)

2001-01-01

There are strong scientific indications that natural change in the Earth system is being accelerated by human intervention. As a result, planet Earth faces the possibility of rapid environmental changes that would have a profound impact on all nations. However, we do not fully understand either the short-term effects of our activities, or their long-term implications - many important scientific questions remain unanswered. The National Aeronautics and Space Administration (NASA) is working with the national and international scientific communities to establish a sound scientific basis for addressing these critical issues through research efforts coordinated under the U.S. Global Change Research Program, the International Geosphere-Biosphere Program, and the World Climate Research Program. The Earth Science Enterprise is NASA's contribution to the U.S. Global Change Research Program. NASA's Earth Science Enterprise will use space- and surface-based measurement systems to provide the scientific basis for understanding global change. The space-based components will provide a constellation of satellites to monitor the Earth from space. A major component of the Earth Science Enterprise is the Earth Observing System (EOS). The overall objective of the EOS Program is to determine the extent, causes, and regional consequences of global climate change. EOS will provide sustained space-based observations that will allow researchers to monitor climate variables over time to determine trends. A constellation of EOS satellites will acquire global data, beginning in 1998 and extending well into the 21st century.

A discussion on mobile satellite system and the myths of CDMA and diversity revealed

NASA Technical Reports Server (NTRS)

Hart, Nicholas; Goerke, Thomas; Jahn, Axel

1995-01-01

The paper explores the myths and facts surrounding: link margins and constellation designs; the use of satellite diversity in a mobile satellite channel; trade-offs in multiple access technique. Different satellite constellations are presented, which are comparable with those used by the big LEO proponents, with the associated trade-offs in the system design. Propagation data and results from various narrowband and wideband measurement campaigns are used to illustrate the expected differences in service performance.

C3Winds: A Novel 3D Wind Observing System to Characterize Severe Weather Events

NASA Astrophysics Data System (ADS)

Kelly, M. A.; Wu, D. L.; Yee, J. H.; Boldt, J.; Demajistre, R.; Reynolds, E.; Tripoli, G. J.; Oman, L.; Prive, N.; Heidinger, A. K.; Wanzong, S.

2015-12-01

The CubeSat Constellation Cloud Winds (C3Winds) is a NASA Earth Venture Instrument (EV-I) concept with the primary objective to resolve high-resolution 3D dynamic structures of severe wind events. Rapid evolution of severe weather events highlights the need for high-resolution mesoscale wind observations. Yet mesoscale observations of severe weather dynamics are quite rare, especially over the ocean where extratropical and tropical cyclones (ETCs and TCs) can undergo explosive development. Measuring wind velocity at the mesoscale from space remains a great challenge, but is critically needed to understand and improve prediction of severe weather and tropical cyclones. Based on compact, visible/IR imagers and a mature stereoscopic technique, C3Winds has the capability to measure high-resolution (~2 km) cloud motion vectors and cloud geometric heights accurately by tracking cloud features from two formation-flying CubeSats, separated by 5-15 minutes. Complementary to lidar wind measurements from space, C3Winds will provide high-resolution wind fields needed for detailed investigations of severe wind events in occluded ETCs, rotational structures inside TC eyewalls, and ozone injections associated with tropopause folding events. Built upon mature imaging technologies and long history of stereoscopic remote sensing, C3Winds provides an innovative, cost-effective solution to global wind observations with the potential for increased diurnal sampling via CubeSat constellation.

Massive pulsating stars observed by BRITE-Constellation. I. The triple system β Centauri (Agena)

NASA Astrophysics Data System (ADS)

Pigulski, A.; Cugier, H.; Popowicz, A.; Kuschnig, R.; Moffat, A. F. J.; Rucinski, S. M.; Schwarzenberg-Czerny, A.; Weiss, W. W.; Handler, G.; Wade, G. A.; Koudelka, O.; Matthews, J. M.; Mochnacki, St.; Orleański, P.; Pablo, H.; Ramiaramanantsoa, T.; Whittaker, G.; Zocłońska, E.; Zwintz, K.

2016-04-01

Context. Asteroseismology of massive pulsating stars of β Cep and SPB types can help us to uncover the internal structure of massive stars and understand certain physical phenomena that are taking place in their interiors. We study β Centauri (Agena), a triple system with two massive fast-rotating early B-type components which show p- and g-mode pulsations; the system's secondary is also known to have a measurable magnetic field. Aims: This paper aims to precisely determine the masses and detect pulsation modes in the two massive components of β Cen with BRITE-Constellation photometry. In addition, seismic models for the components are considered and the effects of fast rotation are discussed. This is done to test the limitations of seismic modeling for this very difficult case. Methods: A simultaneous fit of visual and spectroscopic orbits is used to self-consistently derive the orbital parameters, and subsequently the masses, of the components. Time-series analysis of BRITE-Constellation data is used to detect pulsation modes and derive their frequencies, amplitudes, phases, and rates of frequency change. Theoretically-predicted frequencies are calculated for the appropriate evolutionary models and their stability is checked. The effects of rotational splitting and coupling are also presented. Results: The derived masses of the two massive components are equal to 12.02 ± 0.13 and 10.58 ± 0.18 M⊙. The parameters of the wider, A-B system, presently approaching periastron passage, are constrained. Analysis of the combined blue- and red-filter BRITE-Constellation photometric data of the system revealed the presence of 19 periodic terms, of which eight are likely g modes, nine are p modes, and the remaining two are combination terms. It cannot be excluded that one or two low-frequency terms are rotational frequencies. It is possible that both components of β Cen are β Cep/SPB hybrids. An attempt to use the apparent changes of frequency to distinguish which modes originate in which component did not succeed, but there is potential for using this method when more BRITE data become available. Conclusions: Agena seems to be one of very few rapidly rotating massive objects with rich p- and g-mode spectra, and precisely known masses. It can therefore be used to gain a better understanding of the excitation of pulsations in relatively rapidly rotating stars and their seismic modeling. Lacking proper mode identification, the pulsation frequencies found in β Cen cannot yet be used to constrain the internal structure of the components, but it may be possible to achieve this in the future with the use of spectroscopy and spectropolarimetry. In particular, these kinds of data can be used for mode identification since they provide new radial velocities. In consequence, they may help to improve the orbital solution, derive more precise masses, magnetic field strength and geometry, inclination angles, and reveal rotation periods. They may also help to assign pulsation frequencies to components. Finally, the case studied here illustrates the potential of BRITE-Constellation data for the detection of rich-frequency spectra of small-amplitude modes in massive pulsating stars. Based on data collected by the BRITE-Constellation satellite mission, built, launched and operated thanks to support from the Austrian Aeronautics and Space Agency and the University of Vienna, the Canadian Space Agency (CSA) and the Foundation for Polish Science & Technology (FNiTP MNiSW) and National Centre for Science (NCN).

Methodology of Evaluating the Science Benefit of Various Satellite/Sensor Constellation Orbital Parameters to an Assimilative Data Forecast Model

DTIC Science & Technology

2015-03-02

and Aurora Spectrograph) inst1uments, and radio 129 occultation data from CHAMP (Challenging Minisatellite Payload), SAC-C (Satellite de 130...Aplicaciones Cientificas-C) [Hajj et al, 2004], IOX (Ionospheric Occultation Experiment) 131 [Straus et al, 2003], and the COSMIC (Constellation Observing...T. K. Meehan, L. 385 J. Romans, M. de la Torre Juarez. and T. P. Yunck (2004), CHAMP and SAC-C atmospheric 386 occultation results and

NASA Lunar Impact Monitoring

NASA Technical Reports Server (NTRS)

Suggs, Robert M.; Moser, D. E.

2015-01-01

The MSFC lunar impact monitoring program began in 2006 in support of environment definition for the Constellation (return to Moon) program. Work continued by the Meteoroid Environment Office after Constellation cancellation. Over 330 impacts have been recorded. A paper published in Icarus reported on the first 5 years of observations and 126 calibrated flashes. Icarus: http://www.sciencedirect.com/science/article/pii/S0019103514002243; ArXiv: http://arxiv.org/abs/1404.6458 A NASA Technical Memorandum on flash locations is in press

A statistical characterization of the Galileo-to-GPS inter-system bias

NASA Astrophysics Data System (ADS)

Gioia, Ciro; Borio, Daniele

2016-11-01

Global navigation satellite system operates using independent time scales and thus inter-system time offsets have to be determined to enable multi-constellation navigation solutions. GPS/Galileo inter-system bias and drift are evaluated here using different types of receivers: two mass market and two professional receivers. Moreover, three different approaches are considered for the inter-system bias determination: in the first one, the broadcast Galileo to GPS time offset is used to align GPS and Galileo time scales. In the second, the inter-system bias is included in the multi-constellation navigation solution and is estimated using the measurements available. Finally, an enhanced algorithm using constraints on the inter-system bias time evolution is proposed. The inter-system bias estimates obtained with the different approaches are analysed and their stability is experimentally evaluated using the Allan deviation. The impact of the inter-system bias on the position velocity time solution is also considered and the performance of the approaches analysed is evaluated in terms of standard deviation and mean errors for both horizontal and vertical components. From the experiments, it emerges that the inter-system bias is very stable and that the use of constraints, modelling the GPS/Galileo inter-system bias behaviour, significantly improves the performance of multi-constellation navigation.

CONSTELL: NASA's Satellite Constellation Model

NASA Technical Reports Server (NTRS)

Theall, Jeffrey R.; Krisko, Paula H.; Opiela, John N.; McKay, Gordon A. (Technical Monitor)

1999-01-01

The CONSTELL program represents an initial effort by the orbital debris modeling group at NASA/JSC to address the particular issues and problems raised by the presence of LEO satellite constellations. It was designed to help NASA better understand the potential orbital debris consequences of having satellite constellations operating in the future in LEO. However, it could also be used by constellation planners to evaluate architecture or design alternatives that might lessen debris consequences for their constellation or lessen the debris effects on other users of space. CONSTELL is designed to perform debris environment projections rapidly so it can support parametric assessments involving either the constellations themselves or the background environment which represents non-constellation users of the space. The projections need to be calculated quickly because a number of projections are often required to adequately span the parameter space of interest. To this end CONSTELL uses the outputs of other NASA debris environment models as inputs, thus doing away with the need for time consuming upfront calculations. Specifically, CONSTELL uses EVOLVE or ORDEM96 debris spatial density results as its background environment, debris cloud snapshot templates to simulate debris cloud propagation, and time dependent orbit profiles of the intact non- functional constellation spacecraft and upper stages. In this paper the environmental consequences of the deployment of particular LEO satellite constellations using the CONSTELL model will be evaluated. Constellations that will undergo a parametric assessment will reflect realistic parameter values. Among other results the increase in loss rate of non-constellation spacecraft, the number of collisions involving constellation elements, and the replacement rate of constellation satellites as a result of debris impact will be presented.

Improving multi-GNSS ultra-rapid orbit determination for real-time precise point positioning

NASA Astrophysics Data System (ADS)

Li, Xingxing; Chen, Xinghan; Ge, Maorong; Schuh, Harald

2018-03-01

Currently, with the rapid development of multi-constellation Global Navigation Satellite Systems (GNSS), the real-time positioning and navigation are undergoing dramatic changes with potential for a better performance. To provide more precise and reliable ultra-rapid orbits is critical for multi-GNSS real-time positioning, especially for the three merging constellations Beidou, Galileo and QZSS which are still under construction. In this contribution, we present a five-system precise orbit determination (POD) strategy to fully exploit the GPS + GLONASS + BDS + Galileo + QZSS observations from CDDIS + IGN + BKG archives for the realization of hourly five-constellation ultra-rapid orbit update. After adopting the optimized 2-day POD solution (updated every hour), the predicted orbit accuracy can be obviously improved for all the five satellite systems in comparison to the conventional 1-day POD solution (updated every 3 h). The orbit accuracy for the BDS IGSO satellites can be improved by about 80, 45 and 50% in the radial, cross and along directions, respectively, while the corresponding accuracy improvement for the BDS MEO satellites reaches about 50, 20 and 50% in the three directions, respectively. Furthermore, the multi-GNSS real-time precise point positioning (PPP) ambiguity resolution has been performed by using the improved precise satellite orbits. Numerous results indicate that combined GPS + BDS + GLONASS + Galileo (GCRE) kinematic PPP ambiguity resolution (AR) solutions can achieve the shortest time to first fix (TTFF) and highest positioning accuracy in all coordinate components. With the addition of the BDS, GLONASS and Galileo observations to the GPS-only processing, the GCRE PPP AR solution achieves the shortest average TTFF of 11 min with 7{°} cutoff elevation, while the TTFF of GPS-only, GR, GE and GC PPP AR solution is 28, 15, 20 and 17 min, respectively. As the cutoff elevation increases, the reliability and accuracy of GPS-only PPP AR solutions decrease dramatically, but there is no evident decrease for the accuracy of GCRE fixed solutions which can still achieve an accuracy of a few centimeters in the east and north components.

Benefits of Using a Mars Forward Strategy for Lunar Surface Systems

NASA Technical Reports Server (NTRS)

Mulqueen, Jack; Griffin, Brand; Smitherman, David; Maples, Dauphne

2009-01-01

This paper identifies potential risk reduction, cost savings and programmatic procurement benefits of a Mars Forward Lunar Surface System architecture that provides commonality or evolutionary development paths for lunar surface system elements applicable to Mars surface systems. The objective of this paper is to identify the potential benefits for incorporating a Mars Forward development strategy into the planned Project Constellation Lunar Surface System Architecture. The benefits include cost savings, technology readiness, and design validation of systems that would be applicable to lunar and Mars surface systems. The paper presents a survey of previous lunar and Mars surface systems design concepts and provides an assessment of previous conclusions concerning those systems in light of the current Project Constellation Exploration Architectures. The operational requirements for current Project Constellation lunar and Mars surface system elements are compared and evaluated to identify the potential risk reduction strategies that build on lunar surface systems to reduce the technical and programmatic risks for Mars exploration. Risk reduction for rapidly evolving technologies is achieved through systematic evolution of technologies and components based on Moore's Law superimposed on the typical NASA systems engineering project development "V-cycle" described in NASA NPR 7120.5. Risk reduction for established or slowly evolving technologies is achieved through a process called the Mars-Ready Platform strategy in which incremental improvements lead from the initial lunar surface system components to Mars-Ready technologies. The potential programmatic benefits of the Mars Forward strategy are provided in terms of the transition from the lunar exploration campaign to the Mars exploration campaign. By utilizing a sequential combined procurement strategy for lunar and Mars exploration surface systems, the overall budget wedges for exploration systems are reduced and the costly technological development gap between the lunar and Mars programs can be eliminated. This provides a sustained level of technological competitiveness as well as maintaining a stable engineering and manufacturing capability throughout the entire duration of Project Constellation.

Flight Computer Design for the Space Technology 5 (ST-5) Mission

NASA Technical Reports Server (NTRS)

Speer, David; Jackson, George; Raphael, Dave; Day, John H. (Technical Monitor)

2001-01-01

As part of NASA's New Millennium Program, the Space Technology 5 mission will validate a variety of technologies for nano-satellite and constellation mission applications. Included are: a miniaturized and low power X-band transponder, a constellation communication and navigation transceiver, a cold gas micro-thruster, two different variable emittance (thermal) controllers, flex cables for solar array power collection, autonomous groundbased constellation management tools, and a new CMOS ultra low-power, radiation-tolerant, +0.5 volt logic technology. The ST-5 focus is on small and low-power. A single-processor, multi-function flight computer will implement direct digital and analog interfaces to all of the other spacecraft subsystems and components. There will not be a distributed data system that uses a standardized serial bus such as MIL-STD-1553 or MIL-STD-1773. The flight software running on the single processor will be responsible for all real-time processing associated with: guidance, navigation and control, command and data handling (C&DH) including uplink/downlink, power switching and battery charge management, science data analysis and storage, intra-constellation communications, and housekeeping data collection and logging. As a nanosatellite trail-blazer for future constellations of up to 100 separate space vehicles, ST-5 will demonstrate a compact (single board), low power (5.5 watts) solution to the data acquisition, control, communications, processing and storage requirements that have traditionally required an entire network of separate circuit boards and/or avionics boxes. In addition to the New Millennium technologies, other major spacecraft subsystems include the power system electronics, a lithium-ion battery, triple-junction solar cell arrays, a science-grade magnetometer, a miniature spinning sun sensor, and a propulsion system.

Tropical Processes Applications for CYGNSS

NASA Technical Reports Server (NTRS)

Lang, Timothy J.

2017-01-01

The Cyclone Global Navigation Satellite System (CYGNSS) is focused primarily on observing extreme winds in the inner core of tropical cyclones But... Named storms will occur in view of CYGNSS constellation for only a small percentage of the time on orbit And... Rapid-update, all-weather sampling of wind speeds has many other applications in Tropical Meteorology So... Many potential tropical processes applications for CYGNSS were identified in previous Workshop - Let's revisit some of these possibilities now that the mission is up.

Off-the-shelf real-time monitoring of satellite constellations in a visual 3-D environment

NASA Technical Reports Server (NTRS)

Schwuttke, Ursula M.; Hervias, Felipe; Cheng, Cecilia Han; Mactutis, Anthony; Angelino, Robert

1996-01-01

The multimission spacecraft analysis system (MSAS) data monitor is a generic software product for future real-time data monitoring and analysis. The system represents the status of a satellite constellation through the shape, color, motion and position of graphical objects floating in a three dimensional virtual reality environment. It may be used for the monitoring of large volumes of data, for viewing results in configurable displays, and for providing high level and detailed views of a constellation of monitored satellites. It is considered that the data monitor is an improvement on conventional graphic and text-based displays as it increases the amount of data that the operator can absorb in a given period, and can be installed and configured without the requirement for software development by the end user. The functionality of the system is described, including: the navigation abilities; the representation of alarms in the cybergrid; limit violation; real-time trend analysis, and alarm status indication.

Impact of local and non-local sources of pollution on background US Ozone: synergy of a low-earth orbiting and geostationary sounder constellation

NASA Astrophysics Data System (ADS)

Bowman, K. W.; Lee, M.

2015-12-01

Dramatic changes in the global distribution of emissions over the last decade have fundamentally altered source-receptor pollution impacts. A new generation of low-earth orbiting (LEO) sounders complimented by geostationary sounders over North America, Europe, and Asia providing a unique opportunity to quantify the current and future trajectory of emissions and their impact on global pollution. We examine the potential of this constellation of air quality sounders to quantify the role of local and non-local sources of pollution on background ozone in the US. Based upon an adjoint sensitivity method, we quantify the role synoptic scale transport of non-US pollution on US background ozone over months representative of different source-receptor relationships. This analysis allows us distinguish emission trajectories from megacities, e.g. Beijing, or regions, e.g., western China, from natural trends on downwind ozone. We subsequently explore how a combination of LEO and GEO observations could help quantify the balance of local emissions against changes in distant sources . These results show how this unprecedented new international ozone observing system can monitor the changing structure of emissions and their impact on global pollution.

Low Cost Micro-Mini-Satellite Remote Sensing Capabilities: in-Orbit Results &Imminent Missions

NASA Astrophysics Data System (ADS)

Stephens, Paul; Sun, Wei; Sweeting, Martin, , Sir

Micro- and mini-satellites are in the process or revolutionising the economics of Earth observation. This will jointly affect the space super-powers who have, since the dawn of the space age, enjoyed an effective monopoly of Earth observation from the high vantage-point of space and also the commercial provision of EO data to value added information producers. The monopoly has been due to the enormous cost hitherto required to build, launch and operate EO satellites. SSTL (UK) has pioneered the development of successful micro and mini-satellites which have demonstrated highly capable Earth Observation functions at a mission cost at least an order of magnitude less than conventional such missions. This dramatic development has brought independent ownership of Earth observation satellites within the affordable reach of every developing nation and even medium-sized commercial concerns. Indeed, the performance of these tiny satellites now exceeds the capability of many of the civil EO satellites in operation only 5 years ago. In 2002, SSTL will launch the first satellite in a constellation that will deliver the first routine 24-hour revisit EO data released into the commercial marketplace. This paper describes the in-orbit EO image data produced by typical micro and minisatellites including the latest imagery from the UoSAT-12 mini satellite launched in April 1999 which carries a 32-metre ground sampling distance multispectral imager and a 10-metre GSD panchromatic camera. In addition, data is presented from the TiungSat-1 and Tsinghua-1 microsatellites launched in 2000, and AlSat-1 (launch scheduled in September 2002). AlSat-1 carries a unique imaging system designed as part of the innovative Disaster Monitoring Constellation providing 32-metre GSD multispectral images with a 600km swath width - together with its five companion microsatellites, the Disaster Monitoring Constellation can provide daily revisit imaging world-wide from orbit. The paper also describes the latest advances in imaging using two new low cost small satellites being built at Surrey. The commercial RapidEye constellation of 4-6 microsatellites is designed to provide daily imaging at 6.5-metre GSD in 6 spectral band over Europe for precision farming applications. At a higher resolution, TopSat is a pilot mission for the UK Ministry of Defence carrying a 2.5-metre GSD panchromatic camera on a highly agile microsatellite, designed to deliver images direct to mobile groundstations in the field.

Compilation of Trade Studies for the Constellation Program Extravehicular Activity Spacesuit Power System

NASA Technical Reports Server (NTRS)

Fincannon, James

2009-01-01

This compilation of trade studies performed from 2005 to 2006 addressed a number of power system design issues for the Constellation Program Extravehicular Activity Spacesuit. Spacesuits were required for spacewalks and in-space activities as well as lunar and Mars surface operations. The trades documented here considered whether solar power was feasible for spacesuits, whether spacesuit power generation should be a distributed or a centralized function, whether self-powered in-space spacesuits were better than umbilically powered ones, and whether the suit power system should be recharged in place or replaced.

The Development and Delivery of On-Demand RADARSAT Constellation Mission Ground Deformation Products Based on Advanced Insar Technology

NASA Astrophysics Data System (ADS)

Samsonov, S. V.; Feng, W.

2017-12-01

InSAR-based mapping of surface deformation (displacement) has proven valuable to a variety of geoscience applications within NRCan. Conventional approaches to InSAR analysis require significant expert intervention to separate useful signal from noise and are not suited to the address the opportunities and challenges presented by the large multi-temporal SAR datasets provided by future radar constellations. The Canada Centre for Mapping and Earth Observation (CCMEO) develops, in support of NRCAN and Government of Canada priorities a framework for automatic generation of standard and advanced deformation products based on Interferometric Synthetic Aperture Radar (InSAR) technology from RADARSAT Constellation Mission (RCM) Synthetic Aperture Radar data. We utilize existing processing algorithms that are currently used for processing RADARSAT-2 data and adapt them to RCM specifications. In addition we develop novel advanced processing algorithms that address large data sets made possible by the satellites' rapid revisit cycle and expand InSAR functionality to regional and national scales across a wide range of time scales. Through automation the system makes it possible to extend the mapping of surface deformation to non-SAR experts. The architecture is scalable and expandable to serve large number of clients and simultaneously address multiple application areas including: natural and anthropogenic hazards, natural resource development, permafrost and glacier monitoring, coastal and environmental change and wetlands mapping.

Compact SAR and Small Satellite Solutions for Earth Observation

NASA Astrophysics Data System (ADS)

LaRosa, M.; L'Abbate, M.

2016-12-01

Requirements for near and short term mission applications (Observation and Reconnaissance, SIGINT, Early Warning, Meteorology,..) are increasingly calling for spacecraft operational responsiveness, flexible configuration, lower cost satellite constellations and flying formations, to improve both the temporal performance of observation systems (revisit, response time) and the remote sensing techniques (distributed sensors, arrays, cooperative sensors). In answer to these users' needs, leading actors in Space Systems for EO are involved in development of Small and Microsatellites solutions. Thales Alenia Space (TAS) has started the "COMPACT-SAR" project to develop a SAR satellite characterized by low cost and reduced mass while providing, at the same time, high image quality in terms of resolution, swath size, and radiometric performance. Compact SAR will embark a X-band SAR based on a deployable reflector antenna fed by an active phased array feed. This concept allows high performance, providing capability of electronic beam steering both in azimuth and elevation planes, improving operational performance over a purely mechanically steered SAR system. Instrument provides both STRIPMAP and SPOTLIGHT modes, and thanks to very high gain antenna, can also provide a real maritime surveillance mode based on a patented Low PRF radar mode. Further developments are in progress considering missions based on Microsatellites technology, which can provide effective solutions for different user needs, such as Operational responsiveness, low cost constellations, distributed observation concept, flying formations, and can be conceived for applications in the field of Observation, Atmosphere sensing, Intelligence, Surveillance, Reconnaissance (ISR), Signal Intelligence. To satisfy these requirements, flexibility of small platforms is a key driver and especially new miniaturization technologies able to optimize the performance. An overview new micros-satellite (based on NIMBUS platform) and mission concepts is provided, such as passive SAR for multi-static imaging and tandem, Medium swath/medium resolution dual pol MICROSAR for in L-C-X band multi-application for maritime surveillance and land monitoring, applications for Space Debris monitoring, precision farming, Atmosphere sensing.

MISTiC Winds, a Micro-Satellite Constellation Approach to High Resolution Observations of the Atmosphere using Infrared Sounding and 3D Winds Measurements

NASA Astrophysics Data System (ADS)

Maschhoff, K. R.; Polizotti, J. J.; Aumann, H. H.; Susskind, J.

2017-12-01

MISTiCTM Winds is an approach to improve short-term weather forecasting based on a miniature high resolution, wide field, thermal emission spectrometry instrument that will provide global tropospheric vertical profiles of atmospheric temperature and humidity at high (3-4 km) horizontal and vertical ( 1 km) spatial resolution. MISTiC's extraordinarily small size, payload mass of less than 15 kg, and minimal cooling requirements can be accommodated aboard a ESPA-Class (50 kg) micro-satellite. Low fabrication and launch costs enable a LEO sun-synchronous sounding constellation that would provide frequent IR vertical profiles and vertically resolved atmospheric motion vector wind observations in the troposphere. These observations are highly complementary to present and emerging environmental observing systems, and would provide a combination of high vertical and horizontal resolution not provided by any other environmental observing system currently in operation. The spectral measurements that would be provided by MISTiC Winds are similar to those of NASA's Atmospheric Infrared Sounder. These new observations, when assimilated into high resolution numerical weather models, would revolutionize short-term and severe weather forecasting, save lives, and support key economic decisions in the energy, air transport, and agriculture arenas-at much lower cost than providing these observations from geostationary orbit. In addition, this observation capability would be a critical tool for the study of transport processes for water vapor, clouds, pollution, and aerosols. In this third year of a NASA Instrument incubator program, the compact infrared spectrometer has been integrated into an airborne version of the instrument for high-altitude flights on a NASA ER2. The purpose of these airborne tests is to examine the potential for improved capabilities for tracking atmospheric motion-vector wind tracer features, and determining their height using hyper-spectral sounding and imaging methods.

GEOScan: A GEOScience Facility From Space

NASA Astrophysics Data System (ADS)

Dyrud, L. P.; Fentzke, J. T.; Anderson, B. J.; Bishop, R. L.; Bust, G. S.; Cahoy, K.; Erlandson, R. E.; Fish, C. S.; Gunter, B. C.; Hall, F. G.; Hilker, T.; Lorentz, S. R.; Mazur, J. E.; Murphy, S. D.; Mustard, J. F.; O'Brien, P. P.; Slagowski, S.; Trenberth, K. E.; Wiscombe, W. J.

2012-12-01

GEOScan is a proposed globally networked orbiting facility that will provide revolutionary, massively dense global geosciences observations. Major scientific research projects are typically conducted using two approaches: community facilities, or investigator led focused missions. GEOScan is a new concept in space science, blending the PI mission and community facility models: it is PI-led, but it carries sensors that are the result of a grass-roots competition, and, uniquely, it preserves open slots for sensors which are purposely not yet decided. The goal is threefold: first, to select sensors that maximize science value for the greatest number of scientific disciplines, second, to target science questions that cannot be answered without simultaneous global space-based measurements, and third to reap the cost advantages of scale manufacturing for space instrumentation. The relatively small size, mass, and power requirements of the GEOScan sensor suite would make it an ideal hosted payload aboard a global constellation of communication satellites, such as Iridium NEXT's 66-satellite constellation or as hosted small-sat payload. Each GEOScan sensor suite consists of 6 instruments: a Radiometer to measure Earth's total outgoing radiation; a GPS Compact Total Electron Content Sensor to image Earth's plasma environment and gravity field; a MicroCam Multispectral Imager to provide the first uniform, instantaneous image of Earth and measure global cloud cover, vegetation, land use, and bright aurora; a Radiation Belt Mapping System (dosimeter) to measure energetic electron and proton distributions; a Compact Earth Observing Spectrometer to measure aerosol-atmospheric composition and vegetation; and MEMS Accelerometers to deduce non-conservative forces aiding gravity and neutral drag studies. These instruments, employed in a constellation, can provide major breakthroughs in Earth and Geospace science, as well as offering a low-cost technology demonstration for operational weather, climate, and land-imaging.

KSC-2009-5542

NASA Image and Video Library

2009-10-20

CAPE CANAVERAL, Fla. - Poised inside Vehicle Assembly Building at NASA's Kennedy Space Center in Florida, the Ares I-X rocket's upper stage is adorned with the American flag, NASA logo, and the logos of the Constellation Program, Ares, and Ares I-X. The transfer of the pad from the Space Shuttle Program to the Constellation Program took place May 31. Modifications made to the pad include the removal of shuttle unique subsystems, such as the orbiter access arm and a section of the gaseous oxygen vent arm, along with the installation of three 600-foot lightning towers, access platforms, environmental control systems and a vehicle stabilization system. Part of the Constellation Program, the Ares I-X is the test vehicle for the Ares I. The Ares I-X flight test is targeted for Oct. 27. For information on the Ares I-X vehicle and flight test, visit http://www.nasa.gov/aresIX. Photo credit: NASA/Kim Shiflett

Autonomy for Constellation

NASA Technical Reports Server (NTRS)

Truszkowski, Walt; Szczur, Martha R. (Technical Monitor)

2000-01-01

The newer types of space systems, which are planned for the future, are placing challenging demands for newer autonomy concepts and techniques. Motivating these challenges are resource constraints. Even though onboard computing power will surely increase in the coming years, the resource constraints associated with space-based processes will continue to be a major factor that needs to be considered when dealing with, for example, agent-based spacecraft autonomy. To realize "economical intelligence", i.e., constrained computational intelligence that can reside within a process under severe resource constraints (time, power, space, etc.), is a major goal for such space systems as the Nanosat constellations. To begin to address the new challenges, we are developing approaches to constellation autonomy with constraints in mind. Within the Agent Concepts Testbed (ACT) at the Goddard Space Flight Center we are currently developing a Nanosat-related prototype for the first of the two-step program.

NASA Propulsion Investments for Exploration and Science

NASA Technical Reports Server (NTRS)

Smith, Bryan K.; Free, James M.; Klem, Mark D.; Priskos, Alex S.; Kynard, Michael H.

2008-01-01

The National Aeronautics and Space Administration (NASA) invests in chemical and electric propulsion systems to achieve future mission objectives for both human exploration and robotic science. Propulsion system requirements for human missions are derived from the exploration architecture being implemented in the Constellation Program. The Constellation Program first develops a system consisting of the Ares I launch vehicle and Orion spacecraft to access the Space Station, then builds on this initial system with the heavy-lift Ares V launch vehicle, Earth departure stage, and lunar module to enable missions to the lunar surface. A variety of chemical engines for all mission phases including primary propulsion, reaction control, abort, lunar ascent, and lunar descent are under development or are in early risk reduction to meet the specific requirements of the Ares I and V launch vehicles, Orion crew and service modules, and Altair lunar module. Exploration propulsion systems draw from Apollo, space shuttle, and commercial heritage and are applied across the Constellation architecture vehicles. Selection of these launch systems and engines is driven by numerous factors including development cost, existing infrastructure, operations cost, and reliability. Incorporation of green systems for sustained operations and extensibility into future systems is an additional consideration for system design. Science missions will directly benefit from the development of Constellation launch systems, and are making advancements in electric and chemical propulsion systems for challenging deep space, rendezvous, and sample return missions. Both Hall effect and ion electric propulsion systems are in development or qualification to address the range of NASA s Heliophysics, Planetary Science, and Astrophysics mission requirements. These address the spectrum of potential requirements from cost-capped missions to enabling challenging high delta-v, long-life missions. Additionally, a high specific impulse chemical engine is in development that will add additional capability to performance-demanding space science missions. In summary, the paper provides a survey of current NASA development and risk reduction propulsion investments for exploration and science.

Global tracking and inventory of military hardware via LEO satellite: A system approach and likely scenario

NASA Technical Reports Server (NTRS)

Bell, David; Estabrook, Polly; Romer, Richard

1995-01-01

A system for global inventory control of electronically tagged military hardware is achievable using a LEO satellite constellation. An equipment Tag can communicate directly to the satellite with a power of 5 watts or less at a data rate of 2400 to 50,000 bps. As examples, two proposed commercial LEO systems, IRIDIUM and ORBCOMM, are both capable of providing global coverage but with dramatically different telecom capacities. Investigation of these two LEO systems as applied to the Tag scenario provides insight into satellite design trade-offs, constellation trade-offs and signal dynamics that effect the performance of a satellite-based global inventory control system.

Constellation crew exploration vehicle, or CEV, is being prepare

NASA Image and Video Library

2007-11-27

In Hangar N at NASA's Kennedy Space Center, a heat shield for the Constellation crew exploration vehicle, or CEV, is being prepared for a demonstration. A developmental heat shield for the Orion spacecraft is being tested and evaluated at Kennedy. The shield was designed and assembled by the Boeing Company in Huntington Beach, Calif., for NASA's Constellation Program. The thermal protection system manufacturing demonstration unit is designed to protect astronauts from extreme heat during re-entry to Earth's atmosphere from low Earth orbit and lunar missions. The CEV will be used to dock and gain access to the International Space Station, travel to the moon in the 2018 timeframe and play a crucial role in exploring Mars.

Optimal satellite sampling to resolve global-scale dynamics in the I-T system

NASA Astrophysics Data System (ADS)

Rowland, D. E.; Zesta, E.; Connor, H. K.; Pfaff, R. F., Jr.

2016-12-01

The recent Decadal Survey highlighted the need for multipoint measurements of ion-neutral coupling processes to study the pathways by which solar wind energy drives dynamics in the I-T system. The emphasis in the Decadal Survey is on global-scale dynamics and processes, and in particular, mission concepts making use of multiple identical spacecraft in low earth orbit were considered for the GDC and DYNAMIC missions. This presentation will provide quantitative assessments of the optimal spacecraft sampling needed to significantly advance our knowledge of I-T dynamics on the global scale.We will examine storm time and quiet time conditions as simulated by global circulation models, and determine how well various candidate satellite constellations and satellite schemes can quantify the plasma and neutral convection patterns and global-scale distributions of plasma density, neutral density, and composition, and their response to changes in the IMF. While the global circulation models are data-starved, and do not contain all the physics that we might expect to observe with a global-scale constellation mission, they are nonetheless an excellent "starting point" for discussions of the implementation of such a mission. The result will be of great utility for the design of future missions, such as GDC, to study the global-scale dynamics of the I-T system.

Constellation analysis of an integrated AIS/remote sensing spaceborne system for ship detection

NASA Astrophysics Data System (ADS)

Graziano, Maria Daniela; D'Errico, Marco; Razzano, Elena

2012-08-01

A future system integrating data from remote sensing and upcoming AIS satellites is analyzed through the development of a novel design method for global, discontinuous coverage constellations. It is shown that 8 AIS satellites suffice to guarantee global coverage and a ship location update of 50 min if the spaceborne AIS receiver has a swath of 2800 nm. Furthermore, synergic utilization of COSMO/SkyMed and Radarsat-C data would provide a mean revisit time of 7 h, with AIS information available within 25 min from SAR data acquisition.

A new multi-angle remote sensing framework for scaling vegetation properties from tower-based spectro-radiometers to next generation "CubeSat"-satellites.

NASA Astrophysics Data System (ADS)

Hilker, T.; Hall, F. G.; Dyrud, L. P.; Slagowski, S.

2014-12-01

Frequent earth observations are essential for assessing the risks involved with global climate change, its feedbacks on carbon, energy and water cycling and consequences for live on earth. Often, satellite-remote sensing is the only practical way to provide such observations at comprehensive spatial scales, but relationships between land surface parameters and remotely sensed observations are mostly empirical and cannot easily be scaled across larger areas or over longer time intervals. For instance, optically based methods frequently depend on extraneous effects that are unrelated to the surface property of interest, including the sun-server geometry or background reflectance. As an alternative to traditional, mono-angle techniques, multi-angle remote sensing can help overcome some of these limitations by allowing vegetation properties to be derived from comprehensive reflectance models that describe changes in surface parameters based on physical principles and radiative transfer theory. Recent results have shown in theoretical and experimental research that multi-angle techniques can be used to infer and scale the photosynthetic rate of vegetation, its biochemical and structural composition robustly from remote sensing. Multi-angle remote sensing could therefore revolutionize estimates of the terrestrial carbon uptake as scaling of primary productivity may provide a quantum leap in understanding the spatial and temporal complexity of terrestrial earth science. Here, we introduce a framework of next generation tower-based instruments to a novel and unique constellation of nano-satellites (Figure 1) that will allow us to systematically scale vegetation parameters from stand to global levels. We provide technical insights, scientific rationale and present results. We conclude that future earth observation from multi-angle satellite constellations, supported by tower based remote sensing will open new opportunities for earth system science and earth system modeling.

SPECIAL SESSION: (H21) on Global Precipitation Mission for Hydrology and Hydrometeorology. Sampling-Error Considerations for GPM-Era Rainfall Products

NASA Technical Reports Server (NTRS)

Bell, Thomas L.; Lau, William K. M. (Technical Monitor)

2002-01-01

The proposed Global Precipitation Mission (GPM) builds on the success of the Tropical Rainfall Measuring Mission (TRMM), offering a constellation of microwave-sensor-equipped smaller satellites in addition to a larger, multiply-instrumented "mother" satellite that will include an improved precipitation radar system to which the precipitation estimates of the smaller satellites can be tuned. Coverage by the satellites will be nearly global rather than being confined as TRMM was to lower latitudes. It is hoped that the satellite constellation can provide observations at most places on the earth at least once every three hours, though practical considerations may force some compromises. The GPM system offers the possibility of providing precipitation maps with much better time resolution than the monthly averages around which TRMM was planned, and therefore opens up new possibilities for hydrology and data assimilation into models. In this talk, methods that were developed for estimating sampling error in the rainfall averages that TRMM is providing will be used to estimate sampling error levels for GPM-era configurations. Possible impacts on GPM products of compromises in the sampling frequency will be discussed.

Implementation of a Collision Probability Prediction Technique for Constellation Maneuver Planning

NASA Technical Reports Server (NTRS)

Concha, Marco a.

2007-01-01

On March 22, 2006, the Space Technology 5 (ST5) constellation spacecraft were successfully delivered to orbit by a Pegasus XI, launch vehicle. An unexpected relative motion experienced by the constellation after orbit insertion brought about a problem. Soon after launch the observed relative position of the inert rocket body was between the leading and the middle spacecraft within the constellation. The successful planning and execution of an orbit maneuver that would create a fly-by of the rocket body was required to establish the.formation. This maneuver would create a close approach that needed to conform to predefined collision probability requirements. On April 21, 2006, the ST5 "155" spacecraft performed a large orbit maneuver and successfully passed the inert Pegasus 3rd Stage Rocket Body on April 30, 2006 15:20 UTC at a distance of 2.55 km with a Probability of Collision of less than 1.0E-06. This paper will outline the technique that was implemented to establish the safe planning and execution of the fly-by maneuver. The method makes use of Gaussian distribution models of state covariance to determine underlying probabilities of collision that arise under low velocity encounters. Specific numerical examples used for this analysis are discussed in detail. The mechanics of this technique are explained to foster deeper understanding of the concepts presented and to improve existing processes for use in future constellation maneuver planning.

Implementing the President's Vision: JPL and NASA's Exploration Systems Mission Directorate

NASA Technical Reports Server (NTRS)

Sander, Michael J.

2006-01-01

As part of the NASA team the Jet Propulsion Laboratory is involved in the Exploration Systems Mission Directorate (ESMD) work to implement the President's Vision for Space exploration. In this slide presentation the roles that are assigned to the various NASA centers to implement the vision are reviewed. The plan for JPL is to use the Constellation program to advance the combination of science an Constellation program objectives. JPL's current participation is to contribute systems engineering support, Command, Control, Computing and Information (C3I) architecture, Crew Exploration Vehicle, (CEV) Thermal Protection System (TPS) project support/CEV landing assist support, Ground support systems support at JSC and KSC, Exploration Communication and Navigation System (ECANS), Flight prototypes for cabin atmosphere instruments

Simulating 3D Spacecraft Constellations for Low Frequency Radio Imaging

NASA Astrophysics Data System (ADS)

Hegedus, A. M.; Amiri, N.; Lazio, J.; Belov, K.; Kasper, J. C.

2016-12-01

Constellations of small spacecraft could be used to realize a low-frequency phased array for either heliophysics or astrophysics observations. However, there are issues that arise with an orbiting array that do not occur on the ground, thus rendering much of the existing radio astronomy software inadequate for data analysis and simulation. In this work we address these issues and consider the performance of two constellation concepts. The first is a 32-spacecraft constellation for astrophysical observations, and the second is a 5-element concept for pointing to the location of radio emission from coronal mass ejections (CMEs). For the first, we fill the software gap by extending the APSYNSIM software to simulate the aperture synthesis for a radio interferometer in orbit. This involves using the dynamic baselines from the relative motion of the individual spacecraft as well as the capability to add galactic noise. The ability to simulate phase errors corresponding to positional uncertainty of the antennas was also added. The upgraded software was then used to model the imaging of a 32 spacecraft constellation that would orbit the moon to image radio galaxies like Cygnus A at .3-30 MHz. Animated images showing the improvement of the dirty image as the orbits progressed were made. RMSE plots that show how well the dirty image matches the input image as a function of integration time were made. For the second concept we performed radio interferometric simulations of the Sun Radio Interferometer Space Experiment (SunRISE) using the Common Astronomy Software Applications (CASA) package. SunRISE is a five spacecraft phased array that would orbit Earth to localize the low frequency radio emission from CMEs. This involved simulating the array in CASA, creating truth images for the CMEs over the entire frequency band of SunRISE, and observing them with the simulated array to see how well it could localize the true position of the CME. The results of our analysis show that we can localize the radio emission originating from the head or flanks of the CMEs in spite of the phase errors introduced by uncertainties in orbit and clock estimation.

A Survey of Cost Estimating Methodologies for Distributed Spacecraft Missions

NASA Technical Reports Server (NTRS)

Foreman, Veronica L.; Le Moigne, Jacqueline; de Weck, Oliver L.

2016-01-01

Satellite constellations and Distributed Spacecraft Mission (DSM) architectures offer unique benefits to Earth observation scientists and unique challenges to cost estimators. The Cost and Risk (CR) module of the Tradespace Analysis Tool for Constellations (TAT-C) being developed by NASA Goddard seeks to address some of these challenges by providing a new approach to cost modeling, which aggregates existing Cost Estimating Relationships (CER) from respected sources, cost estimating best practices, and data from existing and proposed satellite designs. Cost estimation through this tool is approached from two perspectives: parametric cost estimating relationships and analogous cost estimation techniques. The dual approach utilized within the TAT-C CR module is intended to address prevailing concerns regarding early design stage cost estimates, and offer increased transparency and fidelity by offering two preliminary perspectives on mission cost. This work outlines the existing cost model, details assumptions built into the model, and explains what measures have been taken to address the particular challenges of constellation cost estimating. The risk estimation portion of the TAT-C CR module is still in development and will be presented in future work. The cost estimate produced by the CR module is not intended to be an exact mission valuation, but rather a comparative tool to assist in the exploration of the constellation design tradespace. Previous work has noted that estimating the cost of satellite constellations is difficult given that no comprehensive model for constellation cost estimation has yet been developed, and as such, quantitative assessment of multiple spacecraft missions has many remaining areas of uncertainty. By incorporating well-established CERs with preliminary approaches to approaching these uncertainties, the CR module offers more complete approach to constellation costing than has previously been available to mission architects or Earth scientists seeking to leverage the capabilities of multiple spacecraft working in support of a common goal.

Drug policy constellations: A Habermasian approach for understanding English drug policy.

PubMed

Stevens, Alex; Zampini, Giulia Federica

2018-07-01

It is increasingly accepted that a view of policy as a rational process of fitting evidence-based means to rationally justified ends is inadequate for understanding the actual processes of drug policy making. We aim to provide a better description and explanation of recent English drug policy decisions. We develop the policy constellation concept from the work of Habermas, in dialogue with data from two contemporary debates in English policy; on decriminalisation of drug possession and on recovery in drug treatment. We collect data on these debates through long-term participant observation, stakeholder interviews (n = 15) and documentary analysis. We show the importance of social asymmetries in power in enabling structurally advantaged groups to achieve the institutionalisation of their moral preferences as well as the reproduction of their social and economic power through the deployment of policies that reflect their material interests and normative beliefs. The most influential actors in English drug policy come together in a 'medico-penal constellation', in which the aims and practices of public health and social control overlap. Formal decriminalisation of possession has not occurred, despite the efforts of members of a challenging constellation which supports it. Recovery was put forward as the aim of drug treatment by members of a more powerfully connected constellation. It has been absorbed into the practice of 'recovery-oriented' drug treatment in a way that maintains the power of public health professionals to determine the form of treatment. Actors who share interests and norms come together in policy constellations. Strategic action within and between constellations creates policies that may not take the form that was intended by any individual actor. These policies do not result from purely rational deliberation, but are produced through 'systematically distorted communication'. They enable the most structurally favoured actors to institutionalise their own normative preferences and structural positions. Copyright © 2018. Published by Elsevier B.V.

Automating Trend Analysis for Spacecraft Constellations

NASA Technical Reports Server (NTRS)

Davis, George; Cooter, Miranda; Updike, Clark; Carey, Everett; Mackey, Jennifer; Rykowski, Timothy; Powers, Edward I. (Technical Monitor)

2001-01-01

Spacecraft trend analysis is a vital mission operations function performed by satellite controllers and engineers, who perform detailed analyses of engineering telemetry data to diagnose subsystem faults and to detect trends that may potentially lead to degraded subsystem performance or failure in the future. It is this latter function that is of greatest importance, for careful trending can often predict or detect events that may lead to a spacecraft's entry into safe-hold. Early prediction and detection of such events could result in the avoidance of, or rapid return to service from, spacecraft safing, which not only results in reduced recovery costs but also in a higher overall level of service for the satellite system. Contemporary spacecraft trending activities are manually intensive and are primarily performed diagnostically after a fault occurs, rather than proactively to predict its occurrence. They also tend to rely on information systems and software that are oudated when compared to current technologies. When coupled with the fact that flight operations teams often have limited resources, proactive trending opportunities are limited, and detailed trend analysis is often reserved for critical responses to safe holds or other on-orbit events such as maneuvers. While the contemporary trend analysis approach has sufficed for current single-spacecraft operations, it will be unfeasible for NASA's planned and proposed space science constellations. Missions such as the Dynamics, Reconnection and Configuration Observatory (DRACO), for example, are planning to launch as many as 100 'nanospacecraft' to form a homogenous constellation. A simple extrapolation of resources and manpower based on single-spacecraft operations suggests that trending for such a large spacecraft fleet will be unmanageable, unwieldy, and cost-prohibitive. It is therefore imperative that an approach to automating the spacecraft trend analysis function be studied, developed, and applied to missions such as DRACO with the intent that mission operations costs be significantly reduced. The goal of the Constellation Spacecraft Trend Analysis Toolkit (CSTAT) project is to serve as the pathfinder for a fully automated trending system to support spacecraft constellations. The development approach to be taken is evolutionary. In the first year of the project, the intent is to significantly advance the state of the art in current trending systems through improved functionality and increased automation. In the second year, the intent is to add an expert system shell, likely through the adaptation of an existing commercial-off-the-shelf (COTS) or government-off-the-shelf (GOTS) tool to implement some level of the trending intelligence that humans currently provide in manual operations. In the third year, the intent is to infuse the resulting technology into a near-term constellation or formation-flying mission to test it and gain experience in automated trending. The lessons learned from the real missions operations experience will then be used to improve the system, and to ultimately incorporate it into a fully autonomous, closed-loop mission operations system that is truly capable of supporting large constellations. In this paper, the process of automating trend analysis for spacecraft constellations will be addressed. First, the results of a survey on automation in spacecraft mission operations in general, and in trending systems in particular will be presented to provide an overview of the current state of the art. Next, a rule-based model for implementing intelligent spacecraft subsystem trending will be then presented, followed by a survey of existing COTS/GOTS tools that could be adapted for implementing such a model. The baseline design and architecture of the CSTAT system will be presented. Finally, some results obtained from initial software tests and demonstrations will be presented.

Autonomous interplanetary constellation design

NASA Astrophysics Data System (ADS)

Chow, Cornelius Channing, II

According to NASA's integrated space technology roadmaps, space-based infrastructures are envisioned as necessary ingredients to a sustained effort in continuing space exploration. Whether it be for extra-terrestrial habitats, roving/cargo vehicles, or space tourism, autonomous space networks will provide a vital communications lifeline for both future robotic and human missions alike. Projecting that the Moon will be a bustling hub of activity within a few decades, a near-term opportunity for in-situ infrastructure development is within reach. This dissertation addresses the anticipated need for in-space infrastructure by investigating a general design methodology for autonomous interplanetary constellations; to illustrate the theory, this manuscript presents results from an application to the Earth-Moon neighborhood. The constellation design methodology is formulated as an optimization problem, involving a trajectory design step followed by a spacecraft placement sequence. Modeling the dynamics as a restricted 3-body problem, the investigated design space consists of families of periodic orbits which play host to the constellations, punctuated by arrangements of spacecraft autonomously guided by a navigation strategy called LiAISON (Linked Autonomous Interplanetary Satellite Orbit Navigation). Instead of more traditional exhaustive search methods, a numerical continuation approach is implemented to map the admissible configuration space. In particular, Keller's pseudo-arclength technique is used to follow folding/bifurcating solution manifolds, which are otherwise inaccessible with other parameter continuation schemes. A succinct characterization of the underlying structure of the local, as well as global, extrema is thus achievable with little a priori intuition of the solution space. Furthermore, the proposed design methodology offers benefits in computation speed plus the ability to handle mildly stochastic systems. An application of the constellation design methodology to the restricted Earth-Moon system, reveals optimal pairwise configurations for various L1, L2, and L5 (halo, axial, and vertical) periodic orbit families. Navigation accuracies, ranging from O (10+/-1) meters in position space, are obtained for the optimal Earth-Moon constellations, given measurement noise on the order of 1 meter.

Geodetic positioning using a global positioning system of satellites

NASA Technical Reports Server (NTRS)

Fell, P. J.

1980-01-01

Geodetic positioning using range, integrated Doppler, and interferometric observations from a constellation of twenty-four Global Positioning System satellites is analyzed. A summary of the proposals for geodetic positioning and baseline determination is given which includes a description of measurement techniques and comments on rank deficiency and error sources. An analysis of variance comparison of range, Doppler, and interferometric time delay to determine their relative geometric strength for baseline determination is included. An analytic examination to the effect of a priori constraints on positioning using simultaneous observations from two stations is presented. Dynamic point positioning and baseline determination using range and Doppler is examined in detail. Models for the error sources influencing dynamic positioning are developed. Included is a discussion of atomic clock stability, and range and Doppler observation error statistics based on random correlated atomic clock error are derived.

A GEOS-Based OSSE for the "MISTiC Winds" Concept

NASA Technical Reports Server (NTRS)

McCarty, W.; Blaisdell, J.; Fuentes, M.; Carvalho, D.; Errico, R.; Gelaro, R.; Kouvaris, L.; Moradi, I.; Pawson, S.; Prive, N.;

Development of Constellation's Launch Control System

NASA Technical Reports Server (NTRS)

Lougheed, Kirk D.; Peaden, Cary J.

2010-01-01

The paper focuses on the National Aeronautics and Space Administration (NASA) Constellation Program's Launch Control System (LCS) development effort at Kennedy Space Center (KSC). It provides a brief history of some preceding efforts to provide launch control and ground processing systems for other NASA programs, and some lessons learned from those experiences. It then provides high level descriptions of the LCS mission, objectives, organization, architecture, and progress. It discusses some of our development tenets, including our use of standards based design and use of off-the-shelf products whenever possible, incremental development cycles, and highly reliable, available, and supportable enterprise class system servers. It concludes with some new lessons learned and our plans for the future.

Overview of the Altair Lunar Lander Thermal Control System Design

NASA Technical Reports Server (NTRS)

Stephan, Ryan A.

2010-01-01

NASA's Constellation Program has been developed to successfully return humans to the Lunar surface by 2020. The Constellation Program includes several different project offices including Altair, which is the next generation Lunar Lander. The planned Altair missions are very different than the Lunar missions accomplished during the Apollo era. These differences have resulted in a significantly different thermal control system architecture. The current paper will summarize the Altair mission architecture and the various operational phases. In addition, the derived thermal requirements will be presented. The paper will conclude with a brief description of the thermal control system designed to meet these unique and challenging thermal requirements.

Assessing GPS Constellation Resiliency in an Urban Canyon Environment

DTIC Science & Technology

2015-03-26

Taipei, Taiwan as his area of interest. His GPS constellation is modeled in the Satellite Toolkit ( STK ) where augmentation satellites can be added and...interaction. SEAS also provides a visual display of the simulation which is useful for verification and debugging portions of the analysis. Furthermore...entire system. Interpreting the model is aided by the visual display of the agents moving in the region of inter- est. Furthermore, SEAS collects

The power of inexpensive satellite constellations

NASA Astrophysics Data System (ADS)

Dyrud, Lars P.; La Tour, Rose; Swartz, William H.; Nag, Sreeja; Lorentz, Steven R.; Hilker, Thomas; Wiscombe, Warren J.; Papadakis, Stergios J.

2014-06-01

Two thematic drivers are motivating the science community towards constellations of small satellites, the revelation that many next generation system science questions are uniquely addressed with sufficient numbers of simultaneous space based measurements, and the realization that space is historically expensive, and in an environment of constrained costs, we must innovate to ―do more with less‖. We present analysis that answers many of the key questions surrounding constellations of scientific satellites, including research that resulted from the GEOScan community based effort originally intended as hosted payloads on Iridium NEXT. We present analysis that answers the question how many satellites does global system science require? Perhaps serendipitously, the analyses show that many of the key science questions independently converge towards similar results, i.e. that approximately 60+ satellites are needed for transformative, as opposed to incremental capability in system science. The current challenge is how to effectively transition products from design to mass production for space based instruments and vehicles. Ideally, the lesson learned from past designs and builds of various space products should pave the way toward a better manufacturing plan that utilizes just a fraction of the prototype`s cost. Using the commercial products industry implementations of mass customization as an example, we will discuss about the benefits of standardization in design requirements for space instruments and vehicles. For example, the instruments (payloads) are designed to have standardized elements, components, or modules that interchangeably work together within a linkage system. We conclude with a discussion on implementation plans and the new paradigms for community and international cooperation enabled by small satellite constellations.

GPM Mission, its Scientific Agenda, and its Ground Validation Program

NASA Technical Reports Server (NTRS)

Smith Eric A.

2004-01-01

The GPM mission is currently planned for start in the late 2010 time frame. From the perspective of NASA s Earth Science Enterprise (ESE) and within the framework of ESE's global water and energy cycle (GWEC) research program, its main scientific goal is to help answer pressing scientific problems concerning how global and regional water cycle processes and precipitation fluctuations and trends influence the variability intrinsic to climate, weather, and hydrology. These problems cut across a hierarchy of space-time scales and include improving understanding of climate-water cycle interactions, developing better techniques for incorporating satellite precipitation measurements into weather and climate predictions, and demonstrating that more accurate, more complete, and better sampled observations of precipitation and other water budget variables used as inputs can improve the ability of prognostic hydrometeorological models in the prediction of hazardous flood-producing storms, seasonal flood/draught conditions, and fresh water resource stores. The GPM mission will expand the scope of precipitation measurement through the use of a constellation of some 9 satellites, one of which will be an advanced TRMM-like core satellite carrying a dual-frequency Ku-Ka band precipitation radar (DPR) and an advanced, multifrequency passive microwave radiometer with vertical-horizontal polarization discrimination (GMI). The other constellation members will include a combination of new dedicated satellites and co-existing operational/research satellites carrying similar (but not identical) passive microwave radiometers. The goal of the constellation is to achieve 3-hour sampling at any spot on the globe -- continuously. The constellation s orbit architecture will consist of a mix of sun-synchronous and non-sun-synchronous satellites with the core satellite providing measurements of calibration-quality rainrates, plus cloud-precipitation microphysical processes, to be used in conjunction with more basic rain retrievals from the other constellation satellites to ensure bias-free constellation coverage.

Aquarius-Pisces Constellation Boundary Update

NASA Astrophysics Data System (ADS)

Durst, Steve

2017-06-01

Observation, mapping and study of Galaxy Stars has provided humanity direction, foundation, clarity and understanding through the ages.Human civilization advances itself using increasing intelligence and knowledge to develop tools and know how, the science of constellation star maps included: All that has been created by humanity, is to serve humanity.When people continue to use constellation star maps that no longer serve people effectively, the maps are updated, as is now the Aquarius-Pisces Constellation Boundary Update (APCBU), which marks 2000 as the year the Sun is in Aquarius at the vernal equinox.The 21st Century APCBU accounts for and incorporates science factors of precession, relativity and galacticity for professional astronomers, and social imperatives of increasing freedom, liberation and egalitarian culture for the 7.5 billion people of Earth.Twenty years into this first century of a new millennium and a new age is an effective time for an APCBU of such elegant simplicity that it changes less than 0.1% of the area of the IAU 1930 official constellation map, which marks 2597 about the year the Sun is in Aquarius at the time of the vernal equinox.The 21st Century APCBU results provide clarity and direction for humanity's next 2,000 years, if not 10,000 or 12,000 years, and advance the official astronomy / science start of the Aquarius Age -- long anticipated, desired, and imperative, especially in America -- by some 600 years.How much attention is increasingly focused on this region of the sky -- such as the recent discovery of 7 Earth-like worlds orbiting the Trappist-1 star in the Aquarius constellation -- will be an epochal 21st Century phenomenon of human science, society, and starlife.

Preliminary Design of Nano Satellite for Regional Navigation System

NASA Astrophysics Data System (ADS)

Fathurrohim, L.; Poetro, R. E.; Kurniadi, B.; Fadillah, P. A.; Iqbal, M.

2018-04-01

A Low cost Regional Navigation Satellite System employing constellation of nano satellites has been proposed for Indonesian coverage. The constellation of Low Earth Orbit nano satellites off course will not be able to give better position fixed to the GPS. However, the design of navigation system has much lower in cost compare to the current navigation system. This paper tells about preliminary design of the proposed regional navigation satellite system. The results of our satellite design has 3 kg on its weight, 10 W on power requirement at the peak condition, and 2.7 years of lifetime. Payload communication of the satellite will use UHF and TT&C communication will use VHF. Total area of solar panel will be 0.11 m2.

ECLSS and Thermal Systems Integration Challenges Across the Constellation Architecture

NASA Technical Reports Server (NTRS)

Carrasquillo, Robyn

2010-01-01

As the Constellation Program completes its initial capability Preliminary Design Review milestone for the Initial Capability phase, systems engineering of the Environmental Control and Life Support (ECLS) and Thermal Systems for the various architecture elements has progressed from the requirements to design phase. As designs have matured for the Ares, Orion, Ground Systems, and Extravehicular (EVA) System, a number of integration challenges have arisen requiring analyses and trades, resulting in changes to the design and/or requirements. This paper will address some of the key integration issues and results, including the Orion-to-Ares shared compartment venting and purging, Orion-to-EVA suit loop integration issues with the suit system, Orion-to-ISS and Orion-to-Altair intermodule ventilation, and Orion and Ground Systems impacts from post-landing environments.

The Impact of Satellite Time Group Delay and Inter-Frequency Differential Code Bias Corrections on Multi-GNSS Combined Positioning

PubMed Central

Ge, Yulong; Zhou, Feng; Sun, Baoqi; Wang, Shengli; Shi, Bo

2017-01-01

We present quad-constellation (namely, GPS, GLONASS, BeiDou and Galileo) time group delay (TGD) and differential code bias (DCB) correction models to fully exploit the code observations of all the four global navigation satellite systems (GNSSs) for navigation and positioning. The relationship between TGDs and DCBs for multi-GNSS is clearly figured out, and the equivalence of TGD and DCB correction models combining theory with practice is demonstrated. Meanwhile, the TGD/DCB correction models have been extended to various standard point positioning (SPP) and precise point positioning (PPP) scenarios in a multi-GNSS and multi-frequency context. To evaluate the effectiveness and practicability of broadcast TGDs in the navigation message and DCBs provided by the Multi-GNSS Experiment (MGEX), both single-frequency GNSS ionosphere-corrected SPP and dual-frequency GNSS ionosphere-free SPP/PPP tests are carried out with quad-constellation signals. Furthermore, the author investigates the influence of differential code biases on GNSS positioning estimates. The experiments show that multi-constellation combination SPP performs better after DCB/TGD correction, for example, for GPS-only b1-based SPP, the positioning accuracies can be improved by 25.0%, 30.6% and 26.7%, respectively, in the N, E, and U components, after the differential code biases correction, while GPS/GLONASS/BDS b1-based SPP can be improved by 16.1%, 26.1% and 9.9%. For GPS/BDS/Galileo the 3rd frequency based SPP, the positioning accuracies are improved by 2.0%, 2.0% and 0.4%, respectively, in the N, E, and U components, after Galileo satellites DCB correction. The accuracy of Galileo-only b1-based SPP are improved about 48.6%, 34.7% and 40.6% with DCB correction, respectively, in the N, E, and U components. The estimates of multi-constellation PPP are subject to different degrees of influence. For multi-constellation combination SPP, the accuracy of single-frequency is slightly better than that of dual-frequency combinations. Dual-frequency combinations are more sensitive to the differential code biases, especially for the 2nd and 3rd frequency combination, such as for GPS/BDS SPP, accuracy improvements of 60.9%, 26.5% and 58.8% in the three coordinate components is achieved after DCB parameters correction. For multi-constellation PPP, the convergence time can be reduced significantly with differential code biases correction. And the accuracy of positioning is slightly better with TGD/DCB correction. PMID:28300787

The Impact of Satellite Time Group Delay and Inter-Frequency Differential Code Bias Corrections on Multi-GNSS Combined Positioning.

PubMed

Ge, Yulong; Zhou, Feng; Sun, Baoqi; Wang, Shengli; Shi, Bo

2017-03-16

We present quad-constellation (namely, GPS, GLONASS, BeiDou and Galileo) time group delay (TGD) and differential code bias (DCB) correction models to fully exploit the code observations of all the four global navigation satellite systems (GNSSs) for navigation and positioning. The relationship between TGDs and DCBs for multi-GNSS is clearly figured out, and the equivalence of TGD and DCB correction models combining theory with practice is demonstrated. Meanwhile, the TGD/DCB correction models have been extended to various standard point positioning (SPP) and precise point positioning (PPP) scenarios in a multi-GNSS and multi-frequency context. To evaluate the effectiveness and practicability of broadcast TGDs in the navigation message and DCBs provided by the Multi-GNSS Experiment (MGEX), both single-frequency GNSS ionosphere-corrected SPP and dual-frequency GNSS ionosphere-free SPP/PPP tests are carried out with quad-constellation signals. Furthermore, the author investigates the influence of differential code biases on GNSS positioning estimates. The experiments show that multi-constellation combination SPP performs better after DCB/TGD correction, for example, for GPS-only b1-based SPP, the positioning accuracies can be improved by 25.0%, 30.6% and 26.7%, respectively, in the N, E, and U components, after the differential code biases correction, while GPS/GLONASS/BDS b1-based SPP can be improved by 16.1%, 26.1% and 9.9%. For GPS/BDS/Galileo the 3rd frequency based SPP, the positioning accuracies are improved by 2.0%, 2.0% and 0.4%, respectively, in the N, E, and U components, after Galileo satellites DCB correction. The accuracy of Galileo-only b1-based SPP are improved about 48.6%, 34.7% and 40.6% with DCB correction, respectively, in the N, E, and U components. The estimates of multi-constellation PPP are subject to different degrees of influence. For multi-constellation combination SPP, the accuracy of single-frequency is slightly better than that of dual-frequency combinations. Dual-frequency combinations are more sensitive to the differential code biases, especially for the 2nd and 3rd frequency combination, such as for GPS/BDS SPP, accuracy improvements of 60.9%, 26.5% and 58.8% in the three coordinate components is achieved after DCB parameters correction. For multi-constellation PPP, the convergence time can be reduced significantly with differential code biases correction. And the accuracy of positioning is slightly better with TGD/DCB correction.

Improved candidate generation and coverage analysis methods for design optimization of symmetric multi-satellite constellations

NASA Astrophysics Data System (ADS)

Matossian, Mark G.

1997-01-01

Much attention in recent years has focused on commercial telecommunications ventures involving constellations of spacecraft in low and medium Earth orbit. These projects often require investments on the order of billions of dollars (US$) for development and operations, but surprisingly little work has been published on constellation design optimization for coverage analysis, traffic simulation and launch sequencing for constellation build-up strategies. This paper addresses the two most critical aspects of constellation orbital design — efficient constellation candidate generation and coverage analysis. Inefficiencies and flaws in the current standard algorithm for constellation modeling are identified, and a corrected and improved algorithm is presented. In the 1970's, John Walker and G. V. Mozhaev developed innovative strategies for continuous global coverage using symmetric non-geosynchronous constellations. (These are sometimes referred to as rosette, or Walker constellations. An example is pictured above.) In 1980, the late Arthur Ballard extended and generalized the work of Walker into a detailed algorithm for the NAVSTAR/GPS program, which deployed a 24 satellite symmetric constellation. Ballard's important contribution was published in his "Rosette Constellations of Earth Satellites."

Advanced Avionics and Processor Systems for Space and Lunar Exploration

NASA Technical Reports Server (NTRS)

Keys, Andrew S.; Adams, James H.; Ray, Robert E.; Johnson, Michael A.; Cressler, John D.

2009-01-01

NASA's newly named Advanced Avionics and Processor Systems (AAPS) project, formerly known as the Radiation Hardened Electronics for Space Environments (RHESE) project, endeavors to mature and develop the avionic and processor technologies required to fulfill NASA's goals for future space and lunar exploration. Over the past year, multiple advancements have been made within each of the individual AAPS technology development tasks that will facilitate the success of the Constellation program elements. This paper provides a brief review of the project's recent technology advancements, discusses their application to Constellation projects, and addresses the project's plans for the coming year.

Science with Constellation-X, Choice of Instrumentation

NASA Technical Reports Server (NTRS)

Hornscheimeier, Ann; White, Nicholas; Tananbaum, Harvey; Garcia, Michael; Bookbinder, Jay; Petre, Robert; Cottam, Jean

2007-01-01

The Constellation X-ray Observatory is one of the two Beyond Einstein Great Observatories and will provide a 100-fold increase in collecting area in high spectral resolving power X-ray instruments over the Chandra and XMM-Newton gratings instruments. The mission has four main science objectives which drive the requirements for the mission. This contribution to the Garmire celebration conference describes these four science areas: Black Holes, Dark Energy, Missing Baryons, and the Neutron Star Equation of State as well as the requirements flow-down that give rise to the choice of instrumentation and implementation for Constellation-X. As we show, each of these science areas place complementary constraints on mission performance parameters such as collecting area, spectral resolving power, timing resolution, and field of view. The mission's capabilities will enable a great breadth of science, and its resources will be open to the community through its General Observer program.

Autonomy Architectures for a Constellation of Spacecraft

NASA Technical Reports Server (NTRS)

Barrett, Anthony

2000-01-01

This paper describes three autonomy architectures for a system that continuously plans to control a fleet of spacecraft using collective mission goals instead of goals of command sequences for each spacecraft. A fleet of self-commanding spacecraft would autonomously coordinate itself to satisfy high level science and engineering goals in a changing partially-understood environment-making feasible the operation of tens of even a hundred spacecraft (such as for interferometer or magnetospheric constellation missions).

Satellite Constellation Optimization for Turkish Armed Forces

DTIC Science & Technology

2013-03-01

capability. 29 III. OPTIMIZATION WITH STK A. ANALYSIS The goal was to minimize the number of satellites and then minimize the number of planes...www.oosa.unvienna.org/pdf/reports/ac105/AC105_1005E.pdf. Wertz, James R. and Larson, Wiley J. “Space Mission Analysis and Design (Third Edition).” Space...Systems Tool Kit software for simulation and analysis of several possible communications and remote sensing satellite constellations covering Turkish

Global design of satellite constellations: a multi-criteria performance comparison of classical walker patterns and new design patterns

NASA Astrophysics Data System (ADS)

Lansard, Erick; Frayssinhes, Eric; Palmade, Jean-Luc

Basically, the problem of designing a multisatellite constellation exhibits a lot of parameters with many possible combinations: total number of satellites, orbital parameters of each individual satellite, number of orbital planes, number of satellites in each plane, spacings between satellites of each plane, spacings between orbital planes, relative phasings between consecutive orbital planes. Hopefully, some authors have theoretically solved this complex problem under simplified assumptions: the permanent (or continuous) coverage by a single and multiple satellites of the whole Earth and zonal areas has been entirely solved from a pure geometrical point of view. These solutions exhibit strong symmetry properties (e.g. Walker, Ballard, Rider, Draim constellations): altitude and inclination are identical, orbital planes and satellites are regularly spaced, etc. The problem with such constellations is their oversimplified and restricted geometrical assumption. In fact, the evaluation function which is used implicitly only takes into account the point-to-point visibility between users and satellites and does not deal with very important constraints and considerations that become mandatory when designing a real satellite system (e.g. robustness to satellite failures, total system cost, common view between satellites and ground stations, service availability and satellite reliability, launch and early operations phase, production constraints, etc.). An original and global methodology relying on a powerful optimization tool based on genetic algorithms has been developed at ALCATEL ESPACE. In this approach, symmetrical constellations can be used as initial conditions of the optimization process together with specific evaluation functions. A multi-criteria performance analysis is conducted and presented here in a parametric way in order to identify and evaluate the main sensitive parameters. Quantitative results are given for three examples in the fields of navigation, telecommunication and multimedia satellite systems. In particular, a new design pattern with very efficient properties in terms of robustness to satellite failures is presented and compared with classical Walker patterns.

Constellation Coverage Analysis

NASA Technical Reports Server (NTRS)

Lo, Martin W. (Compiler)

1997-01-01

The design of satellite constellations requires an understanding of the dynamic global coverage provided by the constellations. Even for a small constellation with a simple circular orbit propagator, the combinatorial nature of the analysis frequently renders the problem intractable. Particularly for the initial design phase where the orbital parameters are still fluid and undetermined, the coverage information is crucial to evaluate the performance of the constellation design. We have developed a fast and simple algorithm for determining the global constellation coverage dynamically using image processing techniques. This approach provides a fast, powerful and simple method for the analysis of global constellation coverage.

43 Cygni observed with BRITE-Constellation

NASA Astrophysics Data System (ADS)

Gössl, S.; Zwintz, K.; Kuschnig, R.

2017-09-01

The γ Doradus star 43 Cygni was observed by BRITE-Toronto for 156 days in 2015. From this data set we identified 37 pulsation frequencies which show a regular period spacing pattern that will be subject of a more detailed asteroseismic analysis.

Overview of the SkyMed/COSMO mission

NASA Astrophysics Data System (ADS)

Caltagirone, Francesco; Spera, Paolo; Vigliotti, R.; Manoni, Gemma

1998-12-01

The impact of natural and man-made disasters on the social and economic progress is going to become more significant, making necessary to consider natural disasters reduction. Therefore civil protection and resource managers need elements to make quicker and better decisions on a day-to-day basis, so giving the start to an emerging world-wide remote sensing market. A deep analysis on the potential users, mainly devoted to Mediterranean basin, highlights that existing and/or planned systems are not able to completely satisfy their requirements. To fulfill this gap, Italy decided to promote the SkyMed/COSMO system, presently financed by the Italian Space Agency. SkyMed/COSMO is a constellation of small satellites for observation, remote sensing and data exploitation for risks management and coastal zone monitoring, conceived to provide products, services and logistics to both institutional and commercial remote sensing users on global scale. Furthermore the system is able to satisfy a broad spectrum of important applications also in the field of the resource management, land use and law enforcement. The SkyMed/COSMO current system architecture foresees a constellation of small satellites in two different orbit planes composed by 4 satellite equipped with X-band SAR and 3 satellites equipped with optical sensors. The system is characterized by good spatial resolution, day and night/all-weather imaging capability and by a very good revisit time. The program, currently in phase B, is carried out by an industrial consortium lead by Alenia Aerospazio.

Temporal resolution requirements of satellite constellations for 30 m global burned area mapping

NASA Astrophysics Data System (ADS)

Melchiorre, A.; Boschetti, L.

2017-12-01

Global burned area maps have been generated systematically with daily, coarse resolution satellite data (Giglio et al. 2013). The production of moderate resolution (10 - 30 m) global burned area products would meet the needs of several user communities: improved carbon emission estimations due to heterogeneous landscapes and for local scale air quality and fire management applications (Mouillot et al. 2014; van der Werf et al. 2010). While the increased spatial resolution reduces the influence of mixed burnt/unburnt pixels and it would increase the spectral separation of burned areas, moderate resolution satellites have reduced temporal resolution (10 - 16 days). Fire causes a land-cover change spectrally visible for a period ranging from a few weeks in savannas to over a year in forested ecosystems (Roy et al. 2010); because clouds, smoke, and other optically thick aerosols limit the number of available observations (Roy et al. 2008; Smith and Wooster 2005), burned areas might disappear before they are observed by moderate resolution sensors. Data fusion from a constellation of different sensors has been proposed to overcome these limits (Boschetti et al. 2015; Roy 2015). In this study, we estimated the probability of moderate resolution satellites and virtual constellations (including Landsat-8/9, Sentinel-2A/B) to provide sufficient observations for burned area mapping globally, and by ecosystem. First, we estimated the duration of the persistence of the signal associated with burned areas by combining the MODIS Global Burned Area and the Nadir BRDF-Adjusted Reflectance Product by characterizing the post-fire trends in reflectance to determine the length of the period in which the burn class is spectrally distinct from the unburned and, therefore, detectable. The MODIS-Terra daily cloud data were then used to estimate the probability of cloud cover. The cloud probability was used at each location to estimate the minimum revisit time needed to obtain at least one cloud-free observation within the duration of the persistence of burned areas. As complementary results, the expected omission error due to insufficient observations was estimated for each of the satellite combination considered making use of the calendar and geometry of acquisition for each of the sensor included in the virtual constellation.

76 FR 41783 - Combined Notice of Filings #2

Federal Register 2010, 2011, 2012, 2013, 2014

2011-07-15

... Commodities Group, Constellation Pwr Source Generation LLC, Constellation NewEnergy, Inc., CER Generation II..., CER Generation, LLC, Constellation Energy Commodities Group M, Constellation Mystic Power, LLC...

The Kepler End-to-End Data Pipeline: From Photons to Far Away Worlds

NASA Technical Reports Server (NTRS)

Cooke, Brian; Thompson, Richard; Standley, Shaun

2012-01-01

Launched by NASA on 6 March 2009, the Kepler Mission has been observing more than 100,000 targets in a single patch of sky between the constellations Cygnus and Lyra almost continuously for the last two years looking for planetary systems using the transit method. As of October 2011, the Kepler spacecraft has collected and returned to Earth just over 290 GB of data, identifying 1235 planet candidates with 25 of these candidates confirmed as planets via ground observation. Extracting the telltale signature of a planetary system from stellar photometry where valid signal transients can be small as a 40 ppm is a difficult and exacting task. The end-to end processing of determining planetary candidates from noisy, raw photometric measurements is discussed.

Ionospheric Simulation System for Satellite Observations and Global Assimilative Modeling Experiments (ISOGAME)

NASA Technical Reports Server (NTRS)

Pi, Xiaoqing; Mannucci, Anthony J.; Verkhoglyadova, Olga P.; Stephens, Philip; Wilson, Brian D.; Akopian, Vardan; Komjathy, Attila; Lijima, Byron A.

2013-01-01

ISOGAME is designed and developed to assess quantitatively the impact of new observation systems on the capability of imaging and modeling the ionosphere. With ISOGAME, one can perform observation system simulation experiments (OSSEs). A typical OSSE using ISOGAME would involve: (1) simulating various ionospheric conditions on global scales; (2) simulating ionospheric measurements made from a constellation of low-Earth-orbiters (LEOs), particularly Global Navigation Satellite System (GNSS) radio occultation data, and from ground-based global GNSS networks; (3) conducting ionospheric data assimilation experiments with the Global Assimilative Ionospheric Model (GAIM); and (4) analyzing modeling results with visualization tools. ISOGAME can provide quantitative assessment of the accuracy of assimilative modeling with the interested observation system. Other observation systems besides those based on GNSS are also possible to analyze. The system is composed of a suite of software that combines the GAIM, including a 4D first-principles ionospheric model and data assimilation modules, an Internal Reference Ionosphere (IRI) model that has been developed by international ionospheric research communities, observation simulator, visualization software, and orbit design, simulation, and optimization software. The core GAIM model used in ISOGAME is based on the GAIM++ code (written in C++) that includes a new high-fidelity geomagnetic field representation (multi-dipole). New visualization tools and analysis algorithms for the OSSEs are now part of ISOGAME.

A Model-based Approach to Controlling the ST-5 Constellation Lights-Out Using the GMSEC Message Bus and Simulink

NASA Technical Reports Server (NTRS)

Witt, Kenneth J.; Stanley, Jason; Shendock, Robert; Mandl, Daniel

2005-01-01

Space Technology 5 (ST-5) is a three-satellite constellation, technology validation mission under the New Millennium Program at NASA to be launched in March 2006. One of the key technologies to be validated is a lights-out, model-based operations approach to be used for one week to control the ST-5 constellation with no manual intervention. The ground architecture features the GSFC Mission Services Evolution Center (GMSEC) middleware, which allows easy plugging in of software components and a standardized messaging protocol over a software bus. A predictive modeling tool built on MatLab's Simulink software package makes use of the GMSEC standard messaging protocol to interface to the Advanced Mission Planning System (AMPS) Scenario Scheduler which controls all activities, resource allocation and real-time re-profiling of constellation resources when non-nominal events occur. The key features of this system, which we refer to as the ST-5 Simulink system, are as follows: Original daily plan is checked to make sure that predicted resources needed are available by comparing the plan against the model. As the plan is run in real-time, the system re-profiles future activities in real-time if planned activities do not occur in the predicted timeframe or fashion. Alert messages are sent out on the GMSEC bus by the system if future predicted problems are detected. This will allow the Scenario Scheduler to correct the situation before the problem happens. The predictive model is evolved automatically over time via telemetry updates thus reducing the cost of implementing and maintaining the models by an order of magnitude from previous efforts at GSFC such as the model-based system built for MAP in the mid-1990's. This paper will describe the key features, lessons learned and implications for future missions once this system is successfully validated on-orbit in 2006.

GPM Plans for Radiometer Intercalibration

NASA Technical Reports Server (NTRS)

Stocker, Erich Franz; Stout, John; Chou, Joyce

2011-01-01

The international Global Precipitation Measurement (GPM) mission led by NASA and JAXA is planned as a multi-radiometer constellation mission. A key mission component is the ability to intercalibrate the Tb from the partner constellation radiometers and create inter-calibrated, mission consistent Tc. One of the enabling strategies for this approach is the launching of a joint NASA/JAXA core satellite which contains a JAXA/NICT provided dual precipitation radar and a NASA provided Microwave Imaging passive radiometer. The observations from these instruments on the core satellite provide the opportunity to develop a transfer reference standard that can then be applied across the partner provided constellation radiometers that enables the creation of mission consistent brightness temperatures. The other aspect of the strategy is the development of a community consensus intercalibration algorithm that will be applied to the Tb observations from partner radiometers and create the best calibrated Tc. Also described is the development of the framework in which the inter-calibration is included in the final algorithm. A part of the latter effort has been the development of a generic, logical structure which can be applied across radiometer types and which guarantees the user community that key information for using Tc properly is recorded. Key

The NASA Cyclone Global Navigation Satellite System (CYGNSS): A Constellation of Bi-static Ocean Scatterometer Microsatellites to Probe the Inner Core of Hurricanes

NASA Astrophysics Data System (ADS)

Ruf, C. S.; Clarizia, M. P.; Ridley, A. J.; Gleason, S.; O'Brien, A.

2014-12-01

The Cyclone Global Navigation Satellite System (CYGNSS) is the first NASA Earth Ventures spaceborne mission. CYGNSS consists of a constellation of eight small observatories carried into orbit on a single launch vehicle. The eight satellites comprise a constellation that flies closely together to measure the ocean surface wind field with unprecedented temporal resolution and spatial coverage, under all precipitating conditions, and over the full dynamic range of wind speeds experienced in a TC. The 8 CYGNSS observatories will fly in 500 km circular orbits at a common inclination of ~35°. Each observatory includes a Delay Doppler Mapping Instrument (DDMI) consisting of a modified GPS receiver capable of measuring surface scattering, a low gain zenith antenna for measurement of the direct GPS signal, and two high gain nadir antennas for measurement of the weaker scattered signal. Each DDMI is capable of measuring 4 simultaneous bi-static reflections, resulting in a total of 32 wind measurements per second across the globe by the full constellation. Simulation studies will be presented which examine the sampling as functions of various orbit parameters of the constellation. For comparison purposes, a similar analysis is conducted using the sampling of several past and present conventional spaceborne ocean wind scatterometers. Differences in the ability of the sensors to resolve the evolution of the TC inner core will be examined. The CYGNSS observatories are currently in Phase C development. An update on the current status of the mission will be presented, including the expected precision, accuracy and spatial and temporal sampling properties of the retrieved winds.

Nonlinear phase noise tolerance for coherent optical systems using soft-decision-aided ML carrier phase estimation enhanced with constellation partitioning

NASA Astrophysics Data System (ADS)

Li, Yan; Wu, Mingwei; Du, Xinwei; Xu, Zhuoran; Gurusamy, Mohan; Yu, Changyuan; Kam, Pooi-Yuen

2018-02-01

A novel soft-decision-aided maximum likelihood (SDA-ML) carrier phase estimation method and its simplified version, the decision-aided and soft-decision-aided maximum likelihood (DA-SDA-ML) methods are tested in a nonlinear phase noise-dominant channel. The numerical performance results show that both the SDA-ML and DA-SDA-ML methods outperform the conventional DA-ML in systems with constant-amplitude modulation formats. In addition, modified algorithms based on constellation partitioning are proposed. With partitioning, the modified SDA-ML and DA-SDA-ML are shown to be useful for compensating the nonlinear phase noise in multi-level modulation systems.

Remote sensing of tropospheric turbulence using GPS radio occultation

NASA Astrophysics Data System (ADS)

Shume, Esayas; Ao, Chi

2016-07-01

Radio occultation (RO) measurements are sensitive to the small-scale irregularities in the atmosphere. In this study, we present a new technique to estimate tropospheric turbulence strength (namely, scintillation index) by analyzing RO amplitude fluctuations in impact parameter domain. GPS RO observations from the COSMIC (Constellation Observing System for Meteorology, Ionosphere, and Climate) satellites enabled us to calculate global maps of scintillation measures, revealing the seasonal, latitudinal, and longitudinal characteristics of the turbulent troposphere. Such information are both difficult and expensive to obtain especially over the oceans. To verify our approach, simulation experiments using the multiple phase screen (MPS) method were conducted. The results show that scintillation indices inferred from the MPS simulations are in good agreement with scintillation measures estimated from COSMIC observations.

Interactions of the space debris environment with mega constellations-Using the example of the OneWeb constellation

NASA Astrophysics Data System (ADS)

Radtke, Jonas; Kebschull, Christopher; Stoll, Enrico

2017-02-01

Recently, several announcements have been published to deploy satellite constellations into Low Earth Orbit (LEO) containing several hundred to thousands of rather small sized objects. The purpose of these constellations is to provide a worldwide internet coverage, even to the remotest areas. Examples of these mega-constellations are one from SpaceX, which is announced to comprise of about 4000 satellites, the Norwegian STEAM network, which is told to contain 4257 satellites, and the OneWeb constellation, which forms one of the smaller constellations with 720 satellites. As example constellation, OneWeb has been chosen. From all announced constellation, OneWeb by far delivered most information, both in regards to constellation design and their plans to encounter space debris issues, which is the reason why it has been chosen for these analyses. In this paper, at first an overview of the planned OneWeb constellation setup is given. From this description, a mission life-cycle is deduced, splitting the complete orbital lifetime of the satellites into four phases. Following, using ESA-MASTER, for each of the mission phases the flux on both single constellations satellites and the complete constellation are performed and the collision probabilities are derived. The focus in this analysis is set on catastrophic collisions. This analysis is then varied parametrically for different operational altitudes of the constellation as well as different lifetimes with different assumptions for the success of post mission disposal (PMD). Following the to-be-expected mean number of collision avoidance manoeuvres during all active mission phases is performed using ARES from ESA's DRAMA tool suite. The same variations as during the flux analysis are considered. Lastly the characteristics of hypothetical OneWeb satellite fragmentation clouds, calculated using the NASA Breakup model, are described and the impact of collision clouds from OneWeb satellites on the constellation itself is analysed.

Waste Collector System Technology Comparisons for Constellation Applications

NASA Technical Reports Server (NTRS)

Broyan, James Lee, Jr.

2006-01-01

The Waste Collection Systems (WCS) for space vehicles have utilized a variety of hardware for collecting human metabolic wastes. It has typically required multiple missions to resolve crew usability and hardware performance issues that are difficult to duplicate on the ground. New space vehicles should leverage off past WCS systems. Past WCS hardware designs are substantially different and unique for each vehicle. However, each WCS can be analyzed and compared as a subset of technologies which encompass fecal collection, urine collection, air systems, pretreatment systems. Technology components from the WCS of various vehicles can then be combined to reduce hardware mass and volume while maximizing use of previous technology and proven human-equipment interfaces. Analysis of past US and Russian WCS are compared and extrapolated to Constellation missions.

Evolution in slow motion

NASA Image and Video Library

2015-09-14

It is known today that merging galaxies play a large role in the evolution of galaxies and the formation of elliptical galaxies in particular. However there are only a few merging systems close enough to be observed in depth. The pair of interacting galaxies picture seen here — known as NGC 3921 — is one of these systems. NGC 3921 — found in the constellation of Ursa Major (The Great Bear) — is an interacting pair of disc galaxies in the late stages of its merger. Observations show that both of the galaxies involved were about the same mass and collided about 700 million years ago. You can see clearly in this image the disturbed morphology, tails and loops characteristic of a post-merger. The clash of galaxies caused a rush of star formation and previous Hubble observations showed over 1000 bright, young star clusters bursting to life at the heart of the galaxy pair.

NASA Earth Observation Systems and Applications for Health and Air Quality

NASA Technical Reports Server (NTRS)

Omar, Ali H.

2015-01-01

There is a growing body of evidence that the environment can affect human health in ways that are both complex and global in scope. To address some of these complexities, NASA maintains a diverse constellation of Earth observing research satellites, and sponsors research in developing satellite data applications across a wide spectrum of areas. These include environmental health; infectious disease; air quality standards, policies, and regulations; and the impact of climate change on health and air quality in a number of interrelated efforts. The Health and Air Quality Applications fosters the use of observations, modeling systems, forecast development, application integration, and the research to operations transition process to address environmental health effects. NASA has been a primary partner with Federal operational agencies over the past nine years in these areas. This talk presents the background of the Health and Air Quality Applications program, recent accomplishments, and a plan for the future.

High-grade, compact spectrometers for Earth observation from SmallSats

NASA Astrophysics Data System (ADS)

van der Wal, L. F.; de Goeij, B. T. G.; Jansen, R.; Oosterling, J. A. J.; Snijders, B.

2016-10-01

The market for nano- and microsatellites is developing rapidly. There is a strong focus on 2D imaging of the Earth's surface, with limited possibilities to obtain spectral information. More demanding applications, such as monitoring trace gases, aerosols or water quality still require advanced imaging instruments, which are large, heavy and expensive. In recent years TNO has investigated and developed different innovative designs to realize advanced spectrometers for space applications in a more compact and cost-effective manner. This offers multiple advantages: a compact instrument can be flown on a much smaller platform (nano- or microsatellite); a low-cost instrument opens up the possibility to fly multiple instruments in a satellite constellation, improving both global coverage and temporal sampling (e.g. to study diurnal processes); a constellation of low-cost instruments may provide added value to the larger scientific and operational satellite missions (e.g. the Copernicus Sentinel missions); and a small, lightweight spectrometer can also be mounted easily on a high-altitude UAV (offering high spatial resolution). Last but not least, a low-cost instrument may allow to break through the `cost spiral': lower cost will allow to take more risk and thus progress more quickly. This may lead to a much faster development cycle than customary for current Earth Observation instruments. To explore the potential of a constellation of low-cost instruments a consortium of Dutch partners was formed, which currently consists of Airbus Defence and Space Netherlands, ISISpace, S and T and TNO. In this paper we will illustrate this new design approach by using the most advanced design of a hyperspectral imaging spectrometer (named `Spectrolite') as an example. We will discuss the different design and manufacturing techniques that were used to realize this compact and low-cost design. Laboratory tests as well as the first preliminary results of airborne measurements with the Spectrolite breadboard will be presented and discussed. The design of Spectrolite offers the flexibility to tune its performance (spectral range, spectral resolution) to a specific application. Thus, based on the same basic system design, Spectrolite offers a range of applications to different clients. To illustrate this, we will present a mission concept to monitor NO2 concentrations over urban areas at high spatial resolution, based on a constellation of small satellites.

Westward tilt of low-latitude plasma blobs as observed by the Swarm constellation

NASA Astrophysics Data System (ADS)

Park, Jaeheung; Lühr, Hermann; Michaelis, Ingo; Stolle, Claudia; Rauberg, Jan; Buchert, Stephan; Gill, Reine; Merayo, Jose M. G.; Brauer, Peter

2015-04-01

In this study we investigate the three-dimensional structure of low-latitude plasma blobs using multi-instrument and multisatellite observations of the Swarm constellation. During the early commissioning phase the Swarm satellites were flying at the same altitude with zonal separation of about 0.5∘ in geographic longitude. Electron density data from the three satellites constrain the blob morphology projected onto the horizontal plane. Magnetic field deflections around blobs, which originate from field-aligned currents near the irregularity boundaries, constrain the blob structure projected onto the plane perpendicular to the ambient magnetic field. As the two constraints are given for two noncoplanar surfaces, we can get information on the three-dimensional structure of blobs. Combined observation results suggest that blobs are contained within tilted shells of geomagnetic flux tubes, which are similar to the shell structure of equatorial plasma bubbles suggested by previous studies.

Dynamics of tethered constellations in Earth orbit

NASA Technical Reports Server (NTRS)

Lorenzini, E.

1986-01-01

Topics covered include station keeping of single-axis and two-axis constellations; single-axis vertical constellations with low-g platform; single-axis vertical constellations with three masses; deployment strategy; and damping of vibrational modes.

On the asteroid hazard

NASA Astrophysics Data System (ADS)

Eneev, T. M.; Akhmetshin, R. Z.; Efimov, G. B.

2012-04-01

The concept of "space patrol" is considered, aimed at discovering and cataloging the majority of celestial bodies that constitute a menace for the Earth [1, 2]. The scheme of "optical barrier" formed by telescopes of the space patrol is analyzed, requirements to the observation system are formulated, and some schemes of sighting the optical barrier region are suggested (for reliable detection of the celestial bodies approaching the Earth and for determination of their orbits). A comparison is made of capabilities of electro-jet engines and traditional chemical engines for arrangement of patrol spacecraft constellation in the Earth's orbit.

A Medium-Scale Traveling Ionospheric Disturbance Observed from the Ground and from Space

NASA Astrophysics Data System (ADS)

Watts, C.; Dymond, K. F.; Coker, C.; Budzien, S.; Bernhardt, P.; Kassim, N.; Lazio, J.; Cohen, A.; Weiler, K.; Crane, P.; Clarke, T.; Rickard, L. J.; Taylor, G. B.; Schinzel, F.; Philstrom, Y.; Kuniyoshi, M.; Close, S.; Colestock, P.; Myers, S.; Datta, A.

2008-12-01

We report the first optical observations from space of a Medium-scale Traveling Ionospheric Disturbance (MSTID) of the Traveling Wave Packet type. The observations were made during the Combined Radio Interferometry and COSMIC Experiment in Tomography Campaign (CRICKET) held on September 15, 2007 at ~0830 UT. The experiment used a Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC also known as FORMOSAT-3) satellite in conjunction with the Very Large Array (VLA) radio telescope, located near Socorro, NM, to study the ionosphere from the global scale down to the regional scale while the TIDs propagated through it. The COSMIC/FORMOSAT-3 satellite measured the ionosphere both horizontally and with altitude while the VLA measured the directions and speed of the TIDs. Our observations provide new information on this poorly understood class of TID

Modified empirical Solar Radiation Pressure model for IRNSS constellation

NASA Astrophysics Data System (ADS)

Rajaiah, K.; Manamohan, K.; Nirmala, S.; Ratnakara, S. C.

2017-11-01

Navigation with Indian Constellation (NAVIC) also known as Indian Regional Navigation Satellite System (IRNSS) is India's regional navigation system designed to provide position accuracy better than 20 m over India and the region extending to 1500 km around India. The reduced dynamic precise orbit estimation is utilized to determine the orbit broadcast parameters for IRNSS constellation. The estimation is mainly affected by the parameterization of dynamic models especially Solar Radiation Pressure (SRP) model which is a non-gravitational force depending on shape and attitude dynamics of the spacecraft. An empirical nine parameter solar radiation pressure model is developed for IRNSS constellation, using two-way range measurements from IRNSS C-band ranging system. The paper addresses the development of modified SRP empirical model for IRNSS (IRNSS SRP Empirical Model, ISEM). The performance of the ISEM was assessed based on overlap consistency, long term prediction, Satellite Laser Ranging (SLR) residuals and compared with ECOM9, ECOM5 and new-ECOM9 models developed by Center for Orbit Determination in Europe (CODE). For IRNSS Geostationary Earth Orbit (GEO) and Inclined Geosynchronous Orbit (IGSO) satellites, ISEM has shown promising results with overlap RMS error better than 5.3 m and 3.5 m respectively. Long term orbit prediction using numerical integration has improved with error better than 80%, 26% and 7.8% in comparison to ECOM9, ECOM5 and new-ECOM9 respectively. Further, SLR based orbit determination with ISEM shows 70%, 47% and 39% improvement over 10 days orbit prediction in comparison to ECOM9, ECOM5 and new-ECOM9 respectively and also highlights the importance of wide baseline tracking network.

Global Coverage from Ad-Hoc Constellations in Rideshare Orbits

NASA Technical Reports Server (NTRS)

Ellis, Armin; Mercury, Michael; Brown, Shannon

2012-01-01

A promising area of small satellite development is in providing higher temporal resolution than larger satellites. Traditional constellations have required specific orbits and dedicated launch vehicles. In this paper we discuss an alternative architecture in which the individual elements of the constellation are launched as rideshare opportunities. We compare the coverage of such an ad-hoc constellation with more traditional constellations. Coverage analysis is based on actual historical data from rideshare opportunities. Our analysis includes ground coverage and temporal revisits for Polar, Tropics, Temperate, and Global regions, comparing ad-hoc and Walker constellation.

Space and ground-based GNSS activities at NOAA

NASA Astrophysics Data System (ADS)

Cucurull, L.

2016-12-01

With the launch of the FORMOSAT-3/COSMIC satellites in April 2006, the availability of Global Navigation Satellite Systems (GNSS) Radio Occultation (RO) observations for operational Numerical Weather Prediction (NWP) applications began. GNSS RO profiles started being assimilated operationally in the major worldwide weather centers soon after. NOAA started assimilating RO data operationally in early 2007. After COSMIC, other missions carrying GNSS RO receivers became available for operational uses. The incorporation of RO observations into the operational assimilation systems was shown to improve global model forecast skill. Since its launch in 2006, the COSMIC constellation has been the mainstay of the global RO system. However, COSMIC is already past the end of its formal lifetime, and only three satellites are still operating. This has motivated NOAA to invest on the COSMIC-2 mission, a 12-satellite constellation, that will replace COSMIC. The first launch, in equatorial orbit, is planned for March 2017. In addition to the space-based component of the GNSS technique, NOAA is assimilating ground-based products into its operational regional models. Although most stations over CONUS provide estimates of Precipitable Water (PW), this is not the case outside the U.S., where the required auxiliary meteorological information is generally not available. Thus, in order to evaluate the impact of ground-based GNSS products on a global weather model, the assimilation of less derived products, such as zenith total delays, rather than PW, is necessary. The talk will include an update on current activities and future plans for the utilization of space and ground-based GNSS products at NOAA. In addition, an update on the COSMIC-2 mission will be discussed.

The 2-D lattice theory of Flower Constellations

NASA Astrophysics Data System (ADS)

Avendaño, Martín E.; Davis, Jeremy J.; Mortari, Daniele

2013-08-01

The 2-D lattice theory of Flower Constellations, generalizing Harmonic Flower Constellations (the symmetric subset of Flower Constellations) as well as the Walker/ Mozhaev constellations, is presented here. This theory is a new general framework to design symmetric constellations using a 2× 2 lattice matrix of integers or by its minimal representation, the Hermite normal form. From a geometrical point of view, the phasing of satellites is represented by a regular pattern (lattice) on a two-Dimensional torus. The 2-D lattice theory of Flower Constellations does not require any compatibility condition and uses a minimum set of integer parameters whose meaning are explored throughout the paper. This general minimum-parametrization framework allows us to obtain all symmetric distribution of satellites. Due to the J_2 effect this design framework is meant for circular orbits and for elliptical orbits at critical inclination, or to design elliptical constellations for the unperturbed Keplerian case.

Determining root correspondence between previously and newly detected objects

DOEpatents

Paglieroni, David W.; Beer, N Reginald

2014-06-17

A system that applies attribute and topology based change detection to networks of objects that were detected on previous scans of a structure, roadway, or area of interest. The attributes capture properties or characteristics of the previously detected objects, such as location, time of detection, size, elongation, orientation, etc. The topology of the network of previously detected objects is maintained in a constellation database that stores attributes of previously detected objects and implicitly captures the geometrical structure of the network. A change detection system detects change by comparing the attributes and topology of new objects detected on the latest scan to the constellation database of previously detected objects.

High precision applications of the global positioning system

NASA Technical Reports Server (NTRS)

Lichten, Stephen M.

1991-01-01

The Global Positioning System (GPS) is a constellation of U.S. defense navigation satellites which can be used for military and civilian positioning applications. A wide variety of GPS scientific applications were identified and precise positioning capabilities with GPS were already demonstrated with data available from the present partial satellite constellation. Expected applications include: measurements of Earth crustal motion, particularly in seismically active regions; measurements of the Earth's rotation rate and pole orientation; high-precision Earth orbiter tracking; surveying; measurements of media propagation delays for calibration of deep space radiometric data in support of NASA planetary missions; determination of precise ground station coordinates; and precise time transfer worldwide.

Fault Management Technology Maturation for NASA's Constellation Program

NASA Technical Reports Server (NTRS)

Waterman, Robert D.

2010-01-01

This slide presentation reviews the maturation of fault management technology in preparation for the Constellation Program. There is a review of the Space Shuttle Main Engine (SSME) and a discussion of a couple of incidents with the shuttle main engine and tanking that indicated the necessity for predictive maintenance. Included is a review of the planned Ares I-X Ground Diagnostic Prototype (GDP) and further information about detection and isolation of faults using Testability Engineering and Maintenance System (TEAMS). Another system that being readied for use that detects anomalies, the Inductive Monitoring System (IMS). The IMS automatically learns how the system behaves and alerts operations it the current behavior is anomalous. The comparison of STS-83 and STS-107 (i.e., the Columbia accident) is shown as an example of the anomaly detection capabilities.

Leveraging Improvements in Precipitation Measuring from GPM Mission to Achieve Prediction Improvements in Climate, Weather and Hydrometeorology

NASA Technical Reports Server (NTRS)

Smith, Eric A.

2002-01-01

The main scientific goal of the GPM mission, currently planned for start in the 2007 time frame, is to investigate important scientific problems arising within the context of global and regional water cycles. These problems cut across a hierarchy of scales and include climate-water cycle interactions, techniques for improving weather and climate predictions, and better methods for combining observed precipitation with hydrometeorological prediction models for applications to hazardous flood-producing storms, seasonal flood/draught conditions, and fresh water resource assessments. The GPM mission will expand the scope of precipitation measurement through the use of a constellation of some 9 satellites, one of which will be an advanced TRMM-like "core" satellite carrying a dual-frequency Ku-Ka band precipitation radar and an advanced, multifrequency passive microwave radiometer with vertical-horizontal polarization discrimination. The other constellation members will include new dedicated satellites and co-existing Operational/research satellites carrying similar (but not identical) passive microwave radiometers. The goal of the constellation is to achieve approximately 3-hour sampling at any spot on the globe. The constellation's orbit architecture will consist of a mix of sun-synchronous and non-sun-synchronous satellites with the core satellite providing measurements of cloud-precipitation microphysical processes plus calibration-quality rainrate retrievals to be used with the other retrieval information to ensure bias-free constellation coverage. GPM is organized internationally, currently involving a partnership between NASA in the US and the National Space Development Agency in Japan. Additionally, the program is actively pursuing agreements with other international partners and domestic scientific agencies and institutions, as well as participation by individual scientists from academia, government, and the private sector to fulfill mission goals and to pave the way for what ultimately is expected to become an internationally-organized operational global precipitation observing system. Notably, the broad societal applications of GPM are reflected in the United Nation s identification of this mission as a foremost candidate for its Peaceful Uses of Space Program. In this presentation, an overview of the GPM mission design will be presented, followed by an explanation of its scientific agenda as an outgrowth of making improvements in rain retrieval accuracy, microphysics dexterity, sampling frequency, and global coverage. All of these improvements offer new means to observe variability in precipitation and water cycle fluxes and to achieve improved predictability of weather, climate, and hydrometeorology. Specifically, the scientific agenda of GPM has been designed to leverage the measurement improvements to improve prognostic model performance, particularly quantitative precipitation forecasting and its linked phenomena at short, intermediate, and extended time scales. The talk will address how GPM measurements will enable better detection of accelerations and decelerations in regional and global water cycle processes and their relationship to climate variability, better impacts of precipitation data assimilation on numerical weather prediction and global climate reanalysis, and better performance from basin scale hydrometeorological models for short and long term flood-drought forecasting and seasonal fresh water resource assessment. Improved hydrometeorological forecasting will be possible by using continuous global precipitation observations to obtain better closure in water budgets and to generate more realistic forcing of the models themselves to achieve more accurate estimates of interception, infiltration, evaporation/transpiration fluxes, storage, and runoff.

Water Cycling &the GPM Mission

NASA Astrophysics Data System (ADS)

Smith, E. A.

2003-04-01

The GPM mission is currently planned for start in the late'07 - early'08 time frame. Its main scientific goal is to help answer pressing scientific problems arising within the context of global and regional water cycles. These problems cut across a hierarchy of scales and include climate-water cycle interactions, techniques for improving weather and climate predictions, and better methods for combining observed precipitation with hydrometeorological prediction models for applications to hazardous flood-producing storms, seasonal flood/draught conditions, and fresh water resource assessments. The GPM mission will expand the scope of precipitation measurement through the use of a constellation of some 9 satellites, one of which will be an advanced TRMM-like "core" satellite carrying a dual-frequency Ku-Ka band precipitation radar and an advanced, multifrequency passive microwave radiometer with vertical-horizontal polarization discrimination. The other constellation members will include new dedicated satellites and co-existing operational/research satellites carrying similar (but not identical) passive microwave radiometers. The goal of the constellation is to achieve 3-hour sampling at any spot on the globe - continuously. The constellation's orbit architecture will consist of a mix of sun-synchronous and non-sun-synchronous satellites with the "core" satellite providing measurements of cloud-precipitation microphysical processes plus calibration-quality rainrates to be used with the other retrieval information to ensure bias-free constellation coverage. GPM is organized internationally, involving existing, pending, projected, and under-study partnerships which will link NASA and NOAA in the US, NASDA in Japan, ESA in Europe, ISRO in India, CNES in France, and possibly ASI in Italy, KARI in South Korea, CSA in Canada, and AEB in Brazil. Additionally, the program is actively pursuing agreements with other international collaborators and domestic scientific agencies and institutions, as well as participation by individual scientists from academia, government, and the private sector to fulfill mission goals and to pave the way for what ultimately is expected to become an internationally-organized operational global precipitation observing system. Notably, the broad societal applications of GPM are reflected in the United Nation's identification of this mission as a foremost candidate for its Peaceful Uses of Space Program. An overview of the GPM mission design is given, followed by an explanation of its scientific agenda as an outgrowth of making improvements in rain retrieval accuracy, microphysics dexterity, sampling frequency, and global coverage. All of these improvements offer new means to observe variability in precipitation and water cycle fluxes, to improve water budget closure at regional and global scales, and to leverage these improvements in achieving improved predictability of weather, climate, and hydrometeorology. Specifically, the scientific agenda of GPM has been designed to leverage the measurement improvements to improve prognostic model performance, particularly quantitative precipitation forecasting and its linked phenomena at short, intermediate, and extended time scales. The talk addresses how GPM measurements will enable more accurate satellite-based calculations of the water cycle relative to where things stand today (two examples will be provided), and how such measurements can be used to evaluate accelerations and decelerations in regional and global water cycle processes and thus improve our understanding of water-driven climatic shifts. These improvements become possible by using more accurate, more microphysically-centric, more frequent, and fully global precipitation observations to achieve better water budget closure and to provide more realistic forcing and assessment of prediction models.

Anticipated Improvements in Precipitation Physics and Understanding of Water Cycle from GPM Mission

NASA Technical Reports Server (NTRS)

Smith, Eric A.

2003-01-01

The GPM mission is currently planned for start in the late-2007 to early-2008 time frame. Its main scientific goal is to help answer pressing scientific problems arising within the context of global and regional water cycles. These problems cut across a hierarchy of scales and include climate-water cycle interactions, techniques for improving weather and climate predictions, and better methods for combining observed precipitation with hydrometeorological prediction models for applications to hazardous flood-producing storms, seasonal flood/draught conditions, and fresh water resource assessments. The GPM mission will expand the scope of precipitation measurement through the use of a constellation of some 9 satellites, one of which will be an advanced TRMM-like core satellite carrying a dual-frequency Ku-Ka band precipitation radar and an advanced, multifrequency passive microwave radiometer with vertical-horizontal polarization discrimination. The other constellation members will include new dedicated satellites and co-existing operational/research satellites carrying similar (but not identical) passive microwave radiometers. The goal of the constellation is to achieve approximately 3-hour sampling at any spot on the globe -- continuously. The constellation s orbit architecture will consist of a mix of sun-synchronous and non-sun-synchronous satellites with the core satellite providing measurements of cloud-precipitation microphysical processes plus calibration-quality rainrate retrievals to be used with the other retrieval information to ensure bias-free constellation coverage. GPM is organized internationally, involving existing, pending, projected, and under-study partnerships which will link NASA and NOAA in the US, NASDA in Japan, ESA in Europe, ISRO in India, CNES in France, and possibly AS1 in Italy, KARI in South Korea, CSA in Canada, and AEB in Brazil. Additionally, the program is actively pursuing agreements with other international collaborators and domestic scientific agencies and institutions, as well as participation by individual scientists from academia, government, and the private sector to fulfill mission goals and to pave the way for what is expected to become an internationally-organized operational global precipitation observing system. Notably, the broad societal applications of GPM are reflected in the United Nation s identification of GPM as a foremost candidate for its Peaceful Uses of Space Program. An overview of the GPM mission design is given, followed by an explanation of its scientific agenda as an outgrowth of making improvements in rain retrieval accuracy, microphysics dexterity, sampling frequency, and global coverage. All of these improvements offer new means to observe variability in precipitation and water cycle fluxes and to achieve improved predictability of weather, climate, and hydrometeorology. Specifically, the scientific agenda of GPM has been designed to leverage the measurement improvements to improve prognostic model performance, particularly quantitative precipitation forecasting and its linked phenomena at short, intermediate, and extended time scales. The talk addresses how GPM measurements will enable better detection of accelerations and decelerations in regional and global water cycle processes and their relationship to climate variability, better impacts of precipitation data assimilation on numerical weather prediction and global climate reanalysis, and better performance from basin scale hydrometeorological models for short and long term flood-drought forecasting and seasonal fresh water resource assessment. These improvements become possible by using more accurate, more microphysically-centric, more frequent, and fully global precipitation observations to achieve better water budget closure and to provide more realistic forcing and assessment of prediction models.

The Latitude and Epoch for the Origin of the Astronomical Lore in MUL.APIN

NASA Astrophysics Data System (ADS)

Schaefer, Bradley E.

2007-05-01

The earliest account of the Mesopotamian constellations (from which the majority of the Greek constellations derived) is a much-copied clay tablet called MUL.APIN. This tablet is a compilation of lists including heliacal rise dates, rise/set pairs, and meridian/rise pairs. The earliest dated example is from 687 BC for a cuneiform tablet found in Assyria. The date for the original astronomical observations has been claimed to be anytime from 2300 BC to soon before 687 BC, although the mainstream view is that the observations are from 1300-1000 BC. These dates are based on analysis of just a few of the observations reported in MUL.APIN. To obtain the best possible date (and latitude), I have itemized 190 observations from MUL.APIN and used a chi-square analysis which returns the best epoch and latitude along with quantified error bars. This analysis is similar to my previously reported work on the astronomical lore of Eudoxus for which I found that the original observations date to 1130+-80 BC and a latitude of 36.0+-0.9 degrees. My analysis of MUL.APIN puts the epoch for the observations at 1370+-100 BC with a latitude of 35.1+-1.2 degrees. This time and place is that of the height of the then-dominant culture of Assyria, and it also corresponds to the first expression of most of the constellations in the archaeological record. This time and place is also the same (within error bars) of the origin of Eudoxus' lore, which happens to have substantial overlaps with MUL.APIN in content. As such, it appears that some original Assyrian observer(s) created a set of observations which were passed down through the centuries by multiple paths, with one path going to the Mesopotamian tradition (through MUL.APIN) and another path going to the Greek tradition (through Eudoxus then Aratus and Hipparchus).

Analysis of migrating diurnal tides detected in FORMOSAT-3/COSMIC temperature data

NASA Astrophysics Data System (ADS)

Pirscher, B.; Foelsche, U.; Borsche, M.; Kirchengast, G.; Kuo, Y.-H.

2010-07-01

The characteristics of atmospheric tides in the upper troposphere and lower stratosphere region are investigated using radio occultation (RO) measurements performed by the Formosa Satellite Mission-3/Constellation Observing System for Meteorology, Ionosphere, and Climate (FORMOSAT-3/COSMIC) satellite constellation and compared to tides observed in short-term forecast model fields of European Centre for Medium-Range Weather Forecasts (ECMWF) and National Centers for Environmental Prediction (NCEP). Spectral analysis of 2 years of monthly data (2007 to 2008) yields the migrating diurnal tide to be the largest spectral component. This diurnal tide shows similar temporal, latitudinal, and altitudinal characteristics in all data sets equatorward of 50°. Beyond 50°, COSMIC local time sampling is insufficient within 1 month, which prevents space-time spectral analysis from isolating atmospheric waves. Diurnal tides of temperature are characterized by largest amplitudes in the tropics (0.8 K to 1.0 K at an altitude of 30 km). Amplitudes of diurnal tides analyzed in model data are more pronounced by ˜20%. An annual cycle of the amplitudes, characteristically linked to the movement of the intertropical convergence zone, is clearly revealed. Tropical diurnal phase features downward progression of waves fronts with a vertical wavelength of 20 km. Extratropical diurnal tides are most pronounced in the model data sets with amplitudes of up to 0.5 K at 30 km. In this analysis we also see the influence of high-altitude initialization of RO data by background information in using data processed by two different centers (University Corporation for Atmospheric Research (UCAR) and Wegener Center (WEGC)). UCAR data, initialized by a climatology without tidal information, exhibit no appreciable extratropical diurnal tides, while WEGC data, initialized by ECMWF forecasts, show more pronounced ones. Overall the results underpin the utility of the local-time resolving COSMIC RO constellation data for monitoring diurnal tide dynamics in the stratosphere. The agreement between observational and model data further confirms that the tidal dynamics is appropriately captured in the models, which is important for other (middle/upper) atmosphere models relying on ECMWF or NCEP dynamics.

77 FR 274 - Combined Notice of Filings #2

Federal Register 2010, 2011, 2012, 2013, 2014

2012-01-04

.... Applicants: Constellation Energy Commodities Group, Baltimore Gas and Electric Company, Constellation Power... that the Commission received the following electric rate filings: Docket Numbers: ER10-2172-006; ER10... Generation, LLC, Constellation NewEnergy, Inc., MXenergy Electric Inc. Description: Constellation MBR...

Challenges in Measuring External Currents Driven by the Solar Wind-Magnetosphere Interaction

NASA Technical Reports Server (NTRS)

Le, Guan; Slavin, James A.; Pfaff, Robert F.

2014-01-01

In studying the Earth's geomagnetism, it has always been a challenge to separate magnetic fields from external currents originating from the ionosphere and magnetosphere. While the internal magnetic field changes very slowly in time scales of years and more, the ionospheric and magnetospheric current systems driven by the solar wind -magnetosphere interaction are very dynamic. They are intimately controlled by the ionospheric electrodynamics and ionospheremagnetosphere coupling. Single spacecraft observations are not able to separate their spatial and temporal variations, and thus to accurately describe their configurations. To characterize and understand the external currents, satellite observations require both good spatial and temporal resolutions. This paper reviews our observations of the external currents from two recent LEO satellite missions: Space Technology 5 (ST-5), NASA's first three-satellite constellation mission in LEO polar orbit, and Communications/Navigation Outage Forecasting System (C/NOFS), an equatorial satellite developed by US Air Force Research Laboratory. We present recommendations for future geomagnetism missions based on these observations.

Micro-satellite constellations for monitoring cryospheric processes and related natural hazards

NASA Astrophysics Data System (ADS)

Kaeaeb, A.; Altena, B.; Mascaro, J.

2016-12-01

Currently, several micro-satellite constellations for earth-observation are planned or under build-up. Here, we assess the potential of the well-advanced Planet satellite constellation for investigating cryospheric processes. In its final stage, the Planet constellation will consist of 150 free-flying micro-satellites in near-polar and ISS orbits. The instruments carry RGB+NIR frame cameras that image the Earth surface in nadir direction with resolutions of 3-5 m, covering 20 x 13 km per image. In its final set-up, the constellation will be able to image the (almost) entire land surface at least once per day, under the limitation of cloud cover. Here, we explore new possibilities for insight into cryospheric processes that this very high repeat cycle combined with high image resolution offer. Based on repeat Planet imagery we derive repeat glacier velocity fields for example glaciers in the northern and southern hemispheres. We find it especially useful to monitor the ice velocities near calving fronts and simultaneously detect changes of the front, pointing to calving events. We also explore deformation fields over creeping mountain permafrost, so-called rockglaciers. As a second, very promising cryospheric application we suggest monitoring of glacier and permafrost related natural hazards. In cases such as temporary lakes, lake outbursts, landslides, rock avalanches, visual information over remote areas and at high frequencies are crucial for hazard assessment, early warning or disaster management. Based on several examples, we demonstrate that massive micro-satellite constellations such Planet's are exactly able to provide this type of information. As a third promising example, we show how such high-repeat optical satellite data are useful to monitor river ice and related jams and flooding. At certain latitudes, the repeat frequency of the data is even high enough to track river ice floes and thus water velocities.

Does Pacman Have Teeth?

NASA Image and Video Library

2011-10-26

NASA Wide-field Infrared Survey Explorer observed the star-forming cloud NGC 281 in the constellation of Cassiopeia as it appears to be chomping through the cosmos, earning it the nickname the Pacman nebula.

78 FR 3042 - J.P. Morgan Securities LLC, et al.; Notice of Application and Temporary Order

Federal Register 2010, 2011, 2012, 2013, 2014

2013-01-15

... Management Inc. (``BSAM''), Bear Stearns Health Innoventures Management, L.L.C. (``BSHIM''), BSCGP Inc. (``BSGCP''), Constellation Growth Capital LLC (``Constellation''), Constellation Ventures Management II, LLC (``Constellation II''), Highbridge Capital Management, LLC (``Highbridge''), JF International...

Comparative analysis of the Rotarix™ vaccine strain and G1P[8] rotaviruses detected before and after vaccine introduction in Belgium.

PubMed

Zeller, Mark; Heylen, Elisabeth; Tamim, Sana; McAllen, John K; Kirkness, Ewen F; Akopov, Asmik; De Coster, Sarah; Van Ranst, Marc; Matthijnssens, Jelle

2017-01-01

G1P[8] rotaviruses are responsible for the majority of human rotavirus infections worldwide. The effect of universal mass vaccination with rotavirus vaccines on circulating G1P[8] rotaviruses is still poorly understood. Therefore we analyzed the complete genomes of the Rotarix™ vaccine strain, and 70 G1P[8] rotaviruses, detected between 1999 and 2010 in Belgium (36 before and 34 after vaccine introduction) to investigate the impact of rotavirus vaccine introduction on circulating G1P[8] strains. All rotaviruses possessed a complete Wa-like genotype constellation, but frequent intra-genogroup reassortments were observed as well as multiple different cluster constellations circulating in a single season. In addition, identical cluster constellations were found to circulate persistently over multiple seasons. The Rotarix™ vaccine strain possessed a unique cluster constellation that was not present in currently circulating G1P[8] strains. At the nucleotide level, the VP6, VP2 and NSP2 gene segments of Rotarix™ were relatively distantly related to any Belgian G1P[8] strain, but other gene segments of Rotarix™ were found in clusters also containing circulating Belgian strains. At the amino acid level, the genetic distance between Rotarix™ and circulating Belgian strains was considerably lower, except for NSP1. When we compared the Belgian G1P[8] strains collected before and after vaccine introduction a reduction in the proportion of strains that were found in the same cluster as the Rotarix™ vaccine strain was observed for most gene segments. The reduction in the proportion of strains belonging to the same cluster may be the result of the vaccine introduction, although natural fluctuations cannot be ruled out.

Occupant Protection during Orion Crew Exploration Vehicle Landings

NASA Technical Reports Server (NTRS)

Gernhardt, Michael L.; Jones, J. A.; Granderson, B. K.; Somers, J. T.

2009-01-01

The constellation program is evaluating current vehicle design capabilities for nominal water landings and contingency land landings of the Orion Crew Exploration vehicle. The Orion Landing Strategy tiger team was formed to lead the technical effort for which associated activities include the current vehicle design, susceptibility to roll control and tip over, reviewing methods for assessing occupant injury during ascent / aborts /landings, developing an alternate seat/attenuation design solution which improves occupant protection and operability, and testing the seat/attenuation system designs to ensure valid results. The EVA physiology, systems and Performance (EPSP) project is leading the effort under the authority of the Tiger Team Steering committee to develop, verify, validate and accredit biodynamics models using a variety of crash and injury databases including NASCAR, Indy Car and military aircraft. The validated biodynamics models will be used by the Constellation program to evaluate a variety of vehicle, seat and restraint designs in the context of multiple nominal and off-nominal landing scenarios. The models will be used in conjunction with Acceptable Injury Risk definitions to provide new occupant protection requirements for the Constellation Program.

Where do the Field Plots Belong? A Multiple-Constraint Sampling Design for the BigFoot Project

NASA Astrophysics Data System (ADS)

Kennedy, R. E.; Cohen, W. B.; Kirschbaum, A. A.; Gower, S. T.

2002-12-01

A key component of a MODIS validation project is effective characterization of biophysical measures on the ground. Fine-grain ecological field measurements must be placed strategically to capture variability at the scale of the MODIS imagery. Here we describe the BigFoot project's revised sampling scheme, designed to simultaneously meet three important goals: capture landscape variability, avoid spatial autocorrelation between field plots, and minimize time and expense of field sampling. A stochastic process places plots in clumped constellations to reduce field sampling costs, while minimizing spatial autocorrelation. This stochastic process is repeated, creating several hundred realizations of plot constellations. Each constellation is scored and ranked according to its ability to match landscape variability in several Landsat-based spectral indices, and its ability to minimize field sampling costs. We show how this approach has recently been used to place sample plots at the BigFoot project's two newest study areas, one in a desert system and one in a tundra system. We also contrast this sampling approach to that already used at the four prior BigFoot project sites.

The Swarm Satellite Constellation Application and Research Facility (SCARF) and Swarm data products

NASA Astrophysics Data System (ADS)

Olsen, Nils; Friis-Christensen, Eigil; Floberghagen, Rune; Alken, Patrick; Beggan, Ciaran D.; Chulliat, Arnaud; Doornbos, Eelco; da Encarnação, João Teixeira; Hamilton, Brian; Hulot, Gauthier; van den IJssel, Jose; Kuvshinov, Alexey; Lesur, Vincent; Lühr, Hermann; Macmillan, Susan; Maus, Stefan; Noja, Max; Olsen, Poul Erik H.; Park, Jaeheung; Plank, Gernot; Püthe, Christoph; Rauberg, Jan; Ritter, Patricia; Rother, Martin; Sabaka, Terence J.; Schachtschneider, Reyko; Sirol, Olivier; Stolle, Claudia; Thébault, Erwan; Thomson, Alan W. P.; Tøffner-Clausen, Lars; Velímský, Jakub; Vigneron, Pierre; Visser, Pieter N.

2013-11-01

Swarm, a three-satellite constellation to study the dynamics of the Earth's magnetic field and its interactions with the Earth system, is expected to be launched in late 2013. The objective of the Swarm mission is to provide the best ever survey of the geomagnetic field and its temporal evolution, in order to gain new insights into the Earth system by improving our understanding of the Earth's interior and environment. In order to derive advanced models of the geomagnetic field (and other higher-level data products) it is necessary to take explicit advantage of the constellation aspect of Swarm. The Swarm SCARF ( S atellite C onstellation A pplication and R esearch F acility) has been established with the goal of deriving Level-2 products by combination of data from the three satellites, and of the various instruments. The present paper describes the Swarm input data products (Level-1b and auxiliary data) used by SCARF, the various processing chains of SCARF, and the Level-2 output data products determined by SCARF.

The ARGOS laser system: green light for ground layer adaptive optics at the LBT

NASA Astrophysics Data System (ADS)

Raab, Walfried; Rabien, Sebastian; Gässler, Wolfgang; Esposito, Simone; Barl, Lothar; Borelli, Jose; Daysenroth, Matthias; Gemperlein, Hans; Kulas, Martin; Ziegleder, Julian

2014-07-01

We report on the development of the laser system of ARGOS, the multiple laser guide star adaptive optics system for the Large Binocular Telescope (LBT). The system uses a total of six high powered, pulsed Nd:YAG lasers frequency-doubled to a wavelength of 532 nm to generate a set of three guide stars above each of the LBT telescopes. The position of each of the LGS constellations on sky as well as the relative position of the individual laser guide stars within this constellation is controlled by a set of steerable mirrors and a fast tip-tilt mirror within the laser system. The entire opto-mechanical system is housed in two hermetically sealed and thermally controlled enclosures on the SX and DX side of the LBT telescope. The laser beams are propagated through two refractive launch telescopes which focus the beams at an altitude of 12 km, creating a constellation of laser guide stars around a 4 arcminute diameter circle by means of Rayleigh scattering. In addition to the GLAO Rayleigh beacon system, ARGOS has also been designed for a possible future upgrade with a hybrid sodium laser - Rayleigh beacon combination, enabling diffraction limited operation. The ARGOS laser system was successfully installed at the LBT in April 2013. Extensive functional tests have been carried out and have verified the operation of the systems according to specifications. The alignment of the laser system with respect to the launch telescope was carried out during two more runs in June and October 2013, followed by the first propagation of laser light on sky in November 2013.

Development of U.S. Government General Technical Requirements for UAS Flight Safety Systems Utilizing the Iridium Satellite Constellation

NASA Technical Reports Server (NTRS)

Murray, Jennifer; Birr, Richard

2010-01-01

This slide presentation reviews the development of technical requirements for Unmanned Aircraft Systems (UAS) utilization of the Iridium Satellite Constellation to provide flight safety. The Federal Aviation Authority (FAA) required an over-the-horizon communication standard to guarantee flight safety before permitting widespread UAS flights in the National Air Space (NAS). This is important to ensure reliable control of UASs during loss-link and over-the-horizon scenarios. The core requirement was to utilize a satellite system to send GPS tracking data and other telemetry from a flight vehicle down to the ground. Iridium was chosen as the system because it is one of the only true satellite systems that has world wide coverage, and the service has a highly reliable link margin. The Iridium system, the flight modems, and the test flight are described.

Polar Satcom System and Related Method

NASA Technical Reports Server (NTRS)

Mitchell, James P. (Inventor)

2016-01-01

A system and method for communication relay via a repeater platform satellite vehicle to a near surface station in the Polar Region is disclosed. A preferred embodiment receives a plurality of positioning and content data from a plurality of constellations of Geosynchronous Equatorial Orbit (GEO) Satellite Vehicles (SAT). Additionally, the system receives a plurality of position, time and altitude data from constellations of available repeater platform (RP) SATs. The system receives a request for content from a near surface station located in an area lacking adequate line-of-sight to the GEO based signal. The system aligns antenna elements onboard the desired RP SATs to amplify and relay the GEO based signal toward the near surface station and vice versa. Additionally, the system commands directional antenna elements onboard the station to send and receive the relayed signal making the GEO based content available to the near surface station.

Research on navigation of satellite constellation based on an asynchronous observation model using X-ray pulsar

NASA Astrophysics Data System (ADS)

Guo, Pengbin; Sun, Jian; Hu, Shuling; Xue, Ju

2018-02-01

Pulsar navigation is a promising navigation method for high-altitude orbit space tasks or deep space exploration. At present, an important reason for restricting the development of pulsar navigation is that navigation accuracy is not high due to the slow update of the measurements. In order to improve the accuracy of pulsar navigation, an asynchronous observation model which can improve the update rate of the measurements is proposed on the basis of satellite constellation which has a broad space for development because of its visibility and reliability. The simulation results show that the asynchronous observation model improves the positioning accuracy by 31.48% and velocity accuracy by 24.75% than that of the synchronous observation model. With the new Doppler effects compensation method in the asynchronous observation model proposed in this paper, the positioning accuracy is improved by 32.27%, and the velocity accuracy is improved by 34.07% than that of the traditional method. The simulation results show that without considering the clock error will result in a filtering divergence.

A New Paradigm in Earth Environmental Monitoring with the CYGNSS Small Satellite Constellation

NASA Technical Reports Server (NTRS)

Ruf, C. S.; Chew, C.; Lang, T.; Morris, M. G.; Kyle, K.; Ridley, A.; Balasubramaniam, R.

2018-01-01

A constellation of small, low-cost satellites is able to make scientifically valuable measurements of the Earth which can be used for weather forecasting, disaster monitoring, and climate studies. Eight CYGNSS satellites were launched into low Earth orbit on December 15, 2016. Each satellite carries a science radar receiver which measures GPS signals reflected from the Earth surface. The signals contain information about the surface, including wind speed over ocean and soil moisture and flooding over land. The satellites are distributed around the globe so that measurements can be made more often to capture extreme weather events. Innovative engineering approaches are used to reduce per satellite cost, increase the number in the constellation, and improve temporal sampling. These include the use of differential drag rather than propulsion to adjust the spacing between satellites and the use of existing GPS signals as the science radars’ transmitter. Initial on-orbit results demonstrate the scientific utility of the CYGNSS observations, and suggest that a new paradigm in spaceborne Earth environmental monitoring is possible.

An Integrated Global Atmospheric Composition Observing System: Progress and Impediments

NASA Astrophysics Data System (ADS)

Keating, T. J.

2016-12-01

In 2003-2005, a vision of an integrated global observing system for atmospheric composition and air quality emerged through several international forums (IGACO, 2004; GEO, 2005). In the decade since, the potential benefits of such a system for improving our understanding and mitigation of health and climate impacts of air pollution have become clearer and the needs more urgent. Some progress has been made towards the goal: technology has developed, capabilities have been demonstrated, and lessons have been learned. In Europe, the Copernicus Atmospheric Monitoring Service has blazed a trail for other regions to follow. Powerful new components of the emerging global system (e.g. a constellation of geostationary instruments) are expected to come on-line in the near term. But there are important gaps in the emerging system that are likely to keep us from achieving for some time the full benefits that were envisioned more than a decade ago. This presentation will explore the components and benefits of an integrated global observing system for atmospheric composition and air quality, some of the gaps and obstacles that exist in our current capabilities and institutions, and efforts that may be needed to achieve the envisioned system.

A satellite constellation optimization for a regional GNSS remote sensing mission

NASA Astrophysics Data System (ADS)

Gavili Kilaneh, Narin; Mashhadi Hossainali, Masoud

2017-04-01

Due to the recent advances in the Global Navigation Satellite System Remote sensing (GNSS¬R) applications, optimization of a satellite orbit to investigate the Earth's properties seems significant. The comparison of the GNSS direct and reflected signals received by a Low Earth Orbit (LEO) satellite introduces a new technique to remotely sense the Earth. Several GNSS¬R missions including Cyclone Global Navigation Satellite System (CYGNSS) have been proposed for different applications such as the ocean wind speed and height monitoring. The geometric optimization of the satellite orbit before starting the mission is a key step for every space mission. Since satellite constellation design varies depending on the application, we have focused on the required geometric criteria for oceanography applications in a specified region. Here, the total number of specular points, their spatial distribution and the accuracy of their position are assumed to be sufficient for oceanography applications. Gleason's method is used to determine the position of specular points. We considered the 2-D lattice and 3-D lattice theory of flower constellation to survey whether a circular orbit or an elliptical one is suitable to improve the solution. Genetic algorithm is implemented to solve the problem. To check the visibility condition between the LEO and GPS satellites, the satellite initial state is propagated by a variable step size numerical integration method. Constellation orbit parameters achieved by optimization provide a better resolution and precession for the specular points in the study area of this research.

The Availability of Space Service for Inter-Satellite Links in Navigation Constellations

PubMed Central

Tang, Yinyin; Wang, Yueke; Chen, Jianyun

2016-01-01

Global navigation satellite systems (GNSS) are widely used in low Earth orbit (LEO) satellite navigation; however, their availability is poor for users in medium Earth orbits (MEO), and high Earth orbits (HEO). With the increasing demand for navigation from MEO and HEO users, the inadequate coverage of GNSS has emerged. Inter-satellite links (ISLs) are used for ranging and communication between navigation satellites and can also serve space users that are outside the navigation constellation. This paper aims to summarize their application method and analyze their service performance. The mathematical model of visibility is proposed and then the availability of time division ISLs is analyzed based on global grid points. The BeiDou navigation constellation is used as an example for numerical simulation. Simulation results show that the availability can be enhanced by scheduling more satellites and larger beams, while the presence of more users lowers the availability. The availability of navigation signals will be strengthened when combined with the signals from the ISLs. ISLs can improve the space service volume (SSV) of navigation constellations, and are therefore a promising method for navigation in MEO/HEO spacecraft. PMID:27548181

Morphology of high-latitude plasma density perturbations as deduced from the total electron content measurements onboard the Swarm constellation

NASA Astrophysics Data System (ADS)

Park, Jaeheung; Lühr, Hermann; Kervalishvili, Guram; Rauberg, Jan; Stolle, Claudia; Kwak, Young-Sil; Lee, Woo Kyoung

2017-01-01

In this study, we investigate the climatology of high-latitude total electron content (TEC) variations as observed by the dual-frequency Global Navigation Satellite Systems (GNSS) receivers onboard the Swarm satellite constellation. The distribution of TEC perturbations as a function of geographic/magnetic coordinates and seasons reasonably agrees with that of the Challenging Minisatellite Payload observations published earlier. Categorizing the high-latitude TEC perturbations according to line-of-sight directions between Swarm and GNSS satellites, we can deduce their morphology with respect to the geomagnetic field lines. In the Northern Hemisphere, the perturbation shapes are mostly aligned with the L shell surface, and this anisotropy is strongest in the nightside auroral (substorm) and subauroral regions and weakest in the central polar cap. The results are consistent with the well-known two-cell plasma convection pattern of the high-latitude ionosphere, which is approximately aligned with L shells at auroral regions and crossing different L shells for a significant part of the polar cap. In the Southern Hemisphere, the perturbation structures exhibit noticeable misalignment to the local L shells. Here the direction toward the Sun has an additional influence on the plasma structure, which we attribute to photoionization effects. The larger offset between geographic and geomagnetic poles in the south than in the north is responsible for the hemispheric difference.

Kepler-62 and the Solar System

NASA Image and Video Library

2013-04-18

This diagram compares the planets of the inner solar system to Kepler-62, a five-planet system about 1,200 light-years from Earth in the constellation Lyra. At seven billion years old, the star is somewhat older than the sun.

Usage of Fault Detection Isolation & Recovery (FDIR) in Constellation (CxP) Launch Operations

NASA Technical Reports Server (NTRS)

Ferrell, Rob; Lewis, Mark; Perotti, Jose; Oostdyk, Rebecca; Spirkovska, Lilly; Hall, David; Brown, Barbara

2010-01-01

This paper will explore the usage of Fault Detection Isolation & Recovery (FDIR) in the Constellation Exploration Program (CxP), in particular Launch Operations at Kennedy Space Center (KSC). NASA's Exploration Technology Development Program (ETDP) is currently funding a project that is developing a prototype FDIR to demonstrate the feasibility of incorporating FDIR into the CxP Ground Operations Launch Control System (LCS). An architecture that supports multiple FDIR tools has been formulated that will support integration into the CxP Ground Operation's Launch Control System (LCS). In addition, tools have been selected that provide fault detection, fault isolation, and anomaly detection along with integration between Flight and Ground elements.

Sensor Webs as Virtual Data Systems for Earth Science

NASA Astrophysics Data System (ADS)

Moe, K. L.; Sherwood, R.

2008-05-01

The NASA Earth Science Technology Office established a 3-year Advanced Information Systems Technology (AIST) development program in late 2006 to explore the technical challenges associated with integrating sensors, sensor networks, data assimilation and modeling components into virtual data systems called "sensor webs". The AIST sensor web program was initiated in response to a renewed emphasis on the sensor web concepts. In 2004, NASA proposed an Earth science vision for a more robust Earth observing system, coupled with remote sensing data analysis tools and advances in Earth system models. The AIST program is conducting the research and developing components to explore the technology infrastructure that will enable the visionary goals. A working statement for a NASA Earth science sensor web vision is the following: On-demand sensing of a broad array of environmental and ecological phenomena across a wide range of spatial and temporal scales, from a heterogeneous suite of sensors both in-situ and in orbit. Sensor webs will be dynamically organized to collect data, extract information from it, accept input from other sensor / forecast / tasking systems, interact with the environment based on what they detect or are tasked to perform, and communicate observations and results in real time. The focus on sensor webs is to develop the technology and prototypes to demonstrate the evolving sensor web capabilities. There are 35 AIST projects ranging from 1 to 3 years in duration addressing various aspects of sensor webs involving space sensors such as Earth Observing-1, in situ sensor networks such as the southern California earthquake network, and various modeling and forecasting systems. Some of these projects build on proof-of-concept demonstrations of sensor web capabilities like the EO-1 rapid fire response initially implemented in 2003. Other projects simulate future sensor web configurations to evaluate the effectiveness of sensor-model interactions for producing improved science predictions. Still other projects are maturing technology to support autonomous operations, communications and system interoperability. This paper will highlight lessons learned by various projects during the first half of the AIST program. Several sensor web demonstrations have been implemented and resulting experience with evolving standards, such as the Open Geospatial Consortium (OGC) Sensor Web Enablement (SWE) among others, will be featured. The role of sensor webs in support of the intergovernmental Group on Earth Observations' Global Earth Observation System of Systems (GEOSS) will also be discussed. The GEOSS vision is a distributed system of systems that builds on international components to supply observing and processing systems that are, in the whole, comprehensive, coordinated and sustained. Sensor web prototypes are under development to demonstrate how remote sensing satellite data, in situ sensor networks and decision support systems collaborate in applications of interest to GEO, such as flood monitoring. Furthermore, the international Committee on Earth Observation Satellites (CEOS) has stepped up to the challenge to provide the space-based systems component for GEOSS. CEOS has proposed "virtual constellations" to address emerging data gaps in environmental monitoring, avoid overlap among observing systems, and make maximum use of existing space and ground assets. Exploratory applications that support the objectives of virtual constellations will also be discussed as a future role for sensor webs.

Long Range Weather Prediction III: Miniaturized Distributed Sensors for Global Atmospheric Measurements

DOE Office of Scientific and Technical Information (OSTI.GOV)

Teller, E; Leith, C; Canavan, G

2001-11-13

We continue consideration of ways-and-means for creating, in an evolutionary, ever-more-powerful manner, a continually-updated data-base of salient atmospheric properties sufficient for finite differenced integration-based, high-fidelity weather prediction over intervals of 2-3 weeks, leveraging the 10{sup 14} FLOPS digital computing systems now coming into existence. A constellation comprised of 10{sup 6}-10{sup 9} small atmospheric sampling systems--high-tech superpressure balloons carrying early 21st century semiconductor devices, drifting with the local winds over the meteorological spectrum of pressure-altitudes--that assays all portions of the troposphere and lower stratosphere remains the central feature of the proposed system. We suggest that these devices should be active-signaling, rather than passive-transponding, as we had previously proposed only for the ground- and aquatic-situated sensors of this system. Instead of periodic interrogation of the intra-atmospheric transponder population by a constellation of sophisticated small satellites in low Earth orbit, we now propose to retrieve information from the instrumented balloon constellation by existing satellite telephony systems, acting as cellular tower-nodes in a global cellular telephony system whose ''user-set'' is the atmospheric-sampling and surface-level monitoring constellations. We thereby leverage the huge investment in cellular (satellite) telephony and GPS technologies, with large technical and economic gains. This proposal minimizes sponsor forward commitment along its entire programmatic trajectory, and moreover may return data of weather-predictive value soon after field activities commence. We emphasize its high near-term value for making better mesoscale, relatively short-term weather predictions with computing-intensive means, and its great long-term utility in enhancing the meteorological basis for global change predictive studies. We again note that adverse impacts of weather involve continuing costs of the order of 1% of GDP, a large fraction of which could be retrieved if high-fidelity predictions of two weeks forward applicability were available. These {approx}more » $$10{sup 2} B annual savings dwarf the <$$1 B costs of operating a rational, long-range weather prediction system of the type proposed.« less

Long Range Weather Prediction III: Miniaturized Distributed Sensors for Global Atmospheric Measurements

DOE R&D Accomplishments Database

Teller, E.; Leith, C.; Canavan, G.; Wood, L.

2001-11-13

We continue consideration of ways-and-means for creating, in an evolutionary, ever-more-powerful manner, a continually-updated data-base of salient atmospheric properties sufficient for finite differenced integration-based, high-fidelity weather prediction over intervals of 2-3 weeks, leveraging the 10{sup 14} FLOPS digital computing systems now coming into existence. A constellation comprised of 10{sup 6}-10{sup 9} small atmospheric sampling systems--high-tech superpressure balloons carrying early 21st century semiconductor devices, drifting with the local winds over the meteorological spectrum of pressure-altitudes--that assays all portions of the troposphere and lower stratosphere remains the central feature of the proposed system. We suggest that these devices should be active-signaling, rather than passive-transponding, as we had previously proposed only for the ground- and aquatic-situated sensors of this system. Instead of periodic interrogation of the intra-atmospheric transponder population by a constellation of sophisticated small satellites in low Earth orbit, we now propose to retrieve information from the instrumented balloon constellation by existing satellite telephony systems, acting as cellular tower-nodes in a global cellular telephony system whose ''user-set'' is the atmospheric-sampling and surface-level monitoring constellations. We thereby leverage the huge investment in cellular (satellite) telephony and GPS technologies, with large technical and economic gains. This proposal minimizes sponsor forward commitment along its entire programmatic trajectory, and moreover may return data of weather-predictive value soon after field activities commence. We emphasize its high near-term value for making better mesoscale, relatively short-term weather predictions with computing-intensive means, and its great long-term utility in enhancing the meteorological basis for global change predictive studies. We again note that adverse impacts of weather involve continuing costs of the order of 1% of GDP, a large fraction of which could be retrieved if high-fidelity predictions of two weeks forward applicability were available. These{approx}$10{sup 2} B annual savings dwarf the<$1 B costs of operating a rational, long-range weather prediction system of the type proposed.

Space Technology 5 - A Successful Micro-Satellite Constellation Mission

NASA Technical Reports Server (NTRS)

Carlisle, Candace; Webb, Evan H.

2007-01-01

The Space Technology 5 (ST5) constellation of three micro-satellites was launched March 22, 2006. During the three-month flight demonstration phase, the ST5 team validated key technologies that will make future low-cost micro-sat constellations possible, demonstrated operability concepts for future micro-sat science constellation missions, and demonstrated the utility of a micro-satellite constellation to perform research-quality science. The ST5 mission was successfully completed in June 2006, demonstrating high-quality science and technology validation results.

Armenian Names of Sky Constellations

NASA Astrophysics Data System (ADS)

Mickaelian, A. M.; Farmanyan, S. V.; Mikayelyan, A. A.

2016-12-01

The work is devoted to the correction and recovery of the Armenian names of the sky constellations, as they were forgotten or distorted during the Soviet years, mainly due to the translation from Russian. A total of 34 constellation names have been corrected. A brief overview of the history of the division of the sky into constellations and their naming is also given. At the end, the list of all 88 constellations is given with the names in Latin, English, Russian and Armenian.

Japanese Global Precipitation Measurement (GPM) mission status and application of satellite-based global rainfall map

NASA Astrophysics Data System (ADS)

Kachi, Misako; Shimizu, Shuji; Kubota, Takuji; Yoshida, Naofumi; Oki, Riko; Kojima, Masahiro; Iguchi, Toshio; Nakamura, Kenji

2010-05-01

As accuracy of satellite precipitation estimates improves and observation frequency increases, application of those data to societal benefit areas, such as weather forecasts and flood predictions, is expected, in addition to research of precipitation climatology to analyze precipitation systems. There is, however, limitation on single satellite observation in coverage and frequency. Currently, the Global Precipitation Measurement (GPM) mission is scheduled under international collaboration to fulfill various user requirements that cannot be achieved by the single satellite, like the Tropical Rainfall Measurement Mission (TRMM). The GPM mission is an international mission to achieve high-accurate and high-frequent rainfall observation over a global area. GPM is composed of a TRMM-like non-sun-synchronous orbit satellite (GPM core satellite) and constellation of satellites carrying microwave radiometer instruments. The GPM core satellite carries the Dual-frequency Precipitation Radar (DPR), which is being developed by the Japan Aerospace Exploration Agency (JAXA) and the National Institute of Information and Communications Technology (NICT), and microwave radiometer provided by the National Aeronautics and Space Administration (NASA). Development of DPR instrument is in good progress for scheduled launch in 2013, and DPR Critical Design Review has completed in July - September 2009. Constellation satellites, which carry a microwave imager and/or sounder, are planned to be launched around 2013 by each partner agency for its own purpose, and will contribute to extending coverage and increasing frequency. JAXA's future mission, the Global Change Observation Mission (GCOM) - Water (GCOM-W) satellite will be one of constellation satellites. The first generation of GCOM-W satellite is scheduled to be launched in 2011, and it carries the Advanced Microwave Scanning Radiometer 2 (AMSR2), which is being developed based on the experience of the AMSR-E on EOS Aqua satellite. Collaboration with GCOM-W is not only limited to its participation to GPM constellation but also coordination in areas of algorithm development and validation in Japan. Generation of high-temporal and high-accurate global rainfall map is one of targets of the GPM mission. As a proto-type for GPM era, JAXA has developed and operates the Global Precipitation Map algorithm in near-real-time since October 2008, and hourly and 0.1-degree resolution binary data and images available at http://sharaku.eorc.jaxa.jp/GSMaP/ four hours after observation. The algorithms are based on outcomes from the Global Satellite Mapping for Precipitation (GSMaP) project, which was sponsored by the Japan Science and Technology Agency (JST) under the Core Research for Evolutional Science and Technology (CREST) framework between 2002 and 2007 (Okamoto et al., 2005; Aonashi et al., 2009; Ushio et al., 2009). Target of GSMaP project is to produce global rainfall maps that are highly accurate and in high temporal and spatial resolution through the development of rain rate retrieval algorithms based on reliable precipitation physical models by using several microwave radiometer data, and comprehensive use of precipitation radar and geostationary infrared imager data. Near-real-time GSMaP data is distributed via internet and utilized by end users. Purpose of data utilization by each user covers broad areas and in world wide; Science researches (model validation, data assimilation, typhoon study, etc.), weather forecast/service, flood warning and rain analysis over river basin, oceanographic condition forecast, agriculture, and education. Toward the GPM era, operational application should be further emphasized as well as science application. JAXA continues collaboration with hydrological communities to utilize satellite-based precipitation data as inputs to future flood prediction and warning system, as well as with meteorological agencies to proceed further data utilization in numerical weather prediction system and forecasts.

Lessons Learned for Cx PRACA. Constellation Program Problem Reporting, Analysis and Corrective Action Process and System

NASA Technical Reports Server (NTRS)

Kelle, Pido I.; Ratterman, Christian; Gibbs, Cecil

2009-01-01

This slide presentation reviews the Constellation Program Problem Reporting, Analysis and Corrective Action Process and System (Cx PRACA). The goal of the Cx PRACA is to incorporate Lessons learned from the Shuttle, ISS, and Orbiter programs by creating a single tool for managing the PRACA process, that clearly defines the scope of PRACA applicability and what must be reported, and defines the ownership and responsibility for managing the PRACA process including disposition approval authority. CxP PRACA is a process, supported by a single information gathering data module which will be integrated with a single CxP Information System, providing interoperability, import and export capability making the CxP PRACA a more effective and user friendly technical and management tool.

Carbon Monoxide Data Assimilation for Atmospheric Composition and Climate Science: Evaluating Performance with Current and Future Observations

NASA Astrophysics Data System (ADS)

Barre, J.; Edwards, D. P.; Gaubert, B.; Worden, H. M.; Arellano, A. F.; Anderson, J. L.

2015-12-01

Current satellite observations of tropospheric composition made from low Earth orbit provide at best one or two measurements each day at any given location. Comparisons of Terra/MOPITT carbon monoxide (CO) and IASI/Metop CO observation assimilations will be presented. We use the DART Ensemble Adjustment Kalman Filter to assimilate observations in the CAM-Chem global chemistry-climate model. Data assimilation impacts due to both different instrument capabilities (i.e. vertical sensitivity and global coverage) will be discussed. Coverage is global but sparse, often with large uncertainties in individual measurements that limit examination of local and regional atmospheric composition over short time periods. This has hindered the operational uptake of these data for monitoring air quality and population exposure, and for initializing and evaluating chemical weather forecasts. By the end of the current decade there are planned geostationary Earth orbit (GEO) satellite missions for atmospheric composition over North America, East Asia and Europe with additional missions proposed. Together, these present the possibility of a constellation of geostationary platforms to achieve continuous time-resolved high-density observations of continental domains for mapping pollutant sources and variability on diurnal and local scales. We describe Observing System Simulation Experiments (OSSEs) to evaluate the contributions of these GEO missions to improve knowledge of near-surface air pollution due to intercontinental long-range transport and quantify chemical precursor emissions. Our approach uses an efficient computational method to sample a high-resolution global GEOS-5 chemistry Nature Run over each geographical region of the GEO constellation. The demonstration carbon monoxide (CO) observation simulator, which will be expanded to other chemical pollutants, currently produces multispectral retrievals (MOPITT-like) and captures realistic scene-dependent variation in measurement vertical sensitivity and cloud cover. The impact of observing over each region is evaluated independently. Winter and summer cases studies are investigated i.e. where emissions, cloud cover and CO lifetime significantly change.

Blind equalization and automatic modulation classification based on subspace for subcarrier MPSK optical communications

NASA Astrophysics Data System (ADS)

Chen, Dan; Guo, Lin-yuan; Wang, Chen-hao; Ke, Xi-zheng

2017-07-01

Equalization can compensate channel distortion caused by channel multipath effects, and effectively improve convergent of modulation constellation diagram in optical wireless system. In this paper, the subspace blind equalization algorithm is used to preprocess M-ary phase shift keying (MPSK) subcarrier modulation signal in receiver. Mountain clustering is adopted to get the clustering centers of MPSK modulation constellation diagram, and the modulation order is automatically identified through the k-nearest neighbor (KNN) classifier. The experiment has been done under four different weather conditions. Experimental results show that the convergent of constellation diagram is improved effectively after using the subspace blind equalization algorithm, which means that the accuracy of modulation recognition is increased. The correct recognition rate of 16PSK can be up to 85% in any kind of weather condition which is mentioned in paper. Meanwhile, the correct recognition rate is the highest in cloudy and the lowest in heavy rain condition.

Enhancements to TetrUSS for NASA Constellation Program

NASA Technical Reports Server (NTRS)

Pandya, Mohagna J.; Frink, Neal T.; Abdol-Hamid, Khaled S.; Samareh, Jamshid A,; Parlete, Edward B.; Taft, James R.

2011-01-01

The NASA Constellation program is utilizing Computational Fluid Dynamics (CFD) predictions for generating aerodynamic databases and design loads for the Ares I, Ares I-X, and Ares V launch vehicles and for aerodynamic databases for the Orion crew exploration vehicle and its launch abort system configuration. This effort presents several challenges to applied aerodynamicists due to complex geometries and flow physics, as well as from the juxtaposition of short schedule program requirements with high fidelity CFD simulations. NASA TetrUSS codes (GridTool/VGRID/USM3D) have been making extensive contributions in this effort. This paper will provide an overview of several enhancements made to the various elements of TetrUSS suite of codes. Representative TetrUSS solutions for selected Constellation program elements will be shown. Best practices guidelines and scripting developed for generating TetrUSS solutions in a production environment will also be described.

Applications of Tethers in Space, Volume 2

NASA Technical Reports Server (NTRS)

Cron, A. C. (Compiler)

1985-01-01

Topics discussed include tethered satellites, tether deployment, satellite systems, science applications, electrodynamic interactions, transportation applications, artificial gravity, constellations, and technology and testing.

The elusive constellations of poverty.

PubMed

Breugelmans, Seger M; Plantinga, Arnoud; Zeelenberg, Marcel; Poluektova, Olga; Efremova, Maria

2017-01-01

Pepper & Nettle describe possible processes underlying what they call a behavioral constellation of deprivation (BCD). Although we are certain about the application of evolutionary models to our understanding of poverty, we are less certain about the utility of behavioral constellations. The empirical record on poverty-related behaviors is much more divergent and broad than such constellations suggest.

Contributions of the observatory of New Mexico State University, Volume 1, no. 4, April 4

NASA Technical Reports Server (NTRS)

1976-01-01

Papers are presented dealing with astronomical observations of the Jupiter Red Spot, Corona Borealis Constellation, and Meteoroids. Calibration of instruments and reduction and analysis of data are discussed.

Analytical investigation of the dynamics of tethered constellations in Earth orbit, phase 2

NASA Technical Reports Server (NTRS)

Lorenzini, E. C.; Arnold, D. A.; Grossi, M. D.; Gullahorn, G. E.

1986-01-01

The g-tuning maneuvers of a 3-mass, vertical tethered system are considered. In particular, the case of reaching a zero-g acceleration level on board the middle mass from a non-zero initial condition is analyzed. A control law that provides a satisfactory transient response is derived. The constellation dynamics in the case of the middle mass travelling from one tether tip to the other is also investigated. Instabilities that take place at the end of the maneuver are analyzed and accommodated by devising suitable damping algorithms.

Overview of Human Factors and Habitability at NASA

NASA Technical Reports Server (NTRS)

Connolly, Janis; Arch, M.; Kaiser, Mary

2009-01-01

This slide presentation reviews the ongoing work on human factors and habitability in the development of the Constellation Program. The focus of the work is on how equipment, spacecraft design, tools, procedures and nutrition be used to improve the health, safety and efficiency of the crewmembers. There are slides showing the components of the Constellation Program, and the conceptual designs of the Orion Crew module, the lunar lander, (i.e., Altair) the microgravity EVA suit, and the lunar surface EVA suit, the lunar rover, and the lunar surface system infrastructure.

Analysis of a Possible Future Degradation in the DORIS Geodetic Results Related to Changes in the Satellite Constellation

NASA Technical Reports Server (NTRS)

Willis, Pascal

2006-01-01

This viewgraph presentation reviews the consequences of losing one or more of the 4 remaining Doppler & Ranging Information System (DORIS) satellites and any impact such a loss might have on geodesy. The goals of this program are to analyze the sensitivity of the current DORIS geodetic results (station position and polar motion) to the size of the DORIS constellation and to verify if some satellites are most important or less important than others. The conclusions of the study are summarized.

Maintaining Aura's Orbit Requirements While Performing Orbit Maintenance Maneuvers Containing an Orbit Normal Delta-V Component

NASA Technical Reports Server (NTRS)

Johnson, Megan R.; Petersen, Jeremy D.

2014-01-01

The Earth Observing System (EOS) Afternoon Constellation consists of five member missions (GCOM-W1, Aqua, CALIPSO, CloudSat, and Aura), each of which maintain a frozen, sun-synchronous orbit with a 16-day repeating ground track that follows the Worldwide Reference System-2 (WRS-2). Under nominal science operations for Aura, the propulsion system is oriented such that the resultant thrust vector is aligned 13.493 degrees away from the velocity vector along the yaw axis. When performing orbit maintenance maneuvers, the spacecraft performs a yaw slew to align the thrust vector in the appropriate direction. A new Drag Make Up (DMU) maneuver operations scheme has been implemented for Aura alleviating the need for the 13.493 degree yaw slew. The focus of this investigation is to assess the impact that no-slew DMU maneuver operations will have on Aura's Mean Local Time (MLT) which drives the required along track separation between Aura and the constellation members, as well as Aura's frozen orbit properties, eccentricity and argument of perigee. Seven maneuver strategies were analyzed to determine the best operational approach. A mirror pole strategy, with maneuvers alternating at the North and South poles, was implemented operationally to minimize impact to the MLT. Additional analysis determined that the mirror pole strategy could be further modified to include frozen orbit maneuvers and thus maintain both MLT and the frozen orbit properties under noslew operations.

Functional and evolutionary correlates of gene constellations in the Drosophila melanogaster genome that deviate from the stereotypical gene architecture

PubMed Central

2010-01-01

Background The biological dimensions of genes are manifold. These include genomic properties, (e.g., X/autosomal linkage, recombination) and functional properties (e.g., expression level, tissue specificity). Multiple properties, each generally of subtle influence individually, may affect the evolution of genes or merely be (auto-)correlates. Results of multidimensional analyses may reveal the relative importance of these properties on the evolution of genes, and therefore help evaluate whether these properties should be considered during analyses. While numerous properties are now considered during studies, most work still assumes the stereotypical solitary gene as commonly depicted in textbooks. Here, we investigate the Drosophila melanogaster genome to determine whether deviations from the stereotypical gene architecture correlate with other properties of genes. Results Deviations from the stereotypical gene architecture were classified as the following gene constellations: Overlapping genes were defined as those that overlap in the 5-prime, exonic, or intronic regions. Chromatin co-clustering genes were defined as genes that co-clustered within 20 kb of transcriptional territories. If this scheme is applied the stereotypical gene emerges as a rare occurrence (7.5%), slightly varied schemes yielded between ~1%-50%. Moreover, when following our scheme, paired-overlapping genes and chromatin co-clustering genes accounted for 50.1 and 42.4% of the genes analyzed, respectively. Gene constellation was a correlate of a number of functional and evolutionary properties of genes, but its statistical effect was ~1-2 orders of magnitude lower than the effects of recombination, chromosome linkage and protein function. Analysis of datasets on male reproductive proteins showed these were biased in their representation of gene constellations and evolutionary rate Ka/Ks estimates, but these biases did not overwhelm the biologically meaningful observation of high evolutionary rates of male reproductive genes. Conclusion Given the rarity of the solitary stereotypical gene, and the abundance of gene constellations that deviate from it, the presence of gene constellations, while once thought to be exceptional in large Eukaryote genomes, might have broader relevance to the understanding and study of the genome. However, according to our definition, while gene constellations can be significant correlates of functional properties of genes, they generally are weak correlates of the evolution of genes. Thus, the need for their consideration would depend on the context of studies. PMID:20497561

Apollo 40th Anniversary History Panel

NASA Image and Video Library

2009-07-15

Cristina Guidi, deputy director, Constellation Systems Division, Exploration Systems Mission Directorate, NASA Headquarters, speaks during an Apollo History and Legacy roundtable discussion, Thursday, July 16, 2009, at NASA Headquarters in Washington. Photo Credit: (NASA/Paul E. Alers)

Linking Satellites Via Earth "Hot Spots" and the Internet to Form Ad Hoc Constellations

NASA Technical Reports Server (NTRS)

Mandl, Dan; Frye, Stu; Grosvenor, Sandra; Ingram, Mary Ann; Langley, John; Miranda, Felix; Lee, Richard Q.; Romanofsky, Robert; Zaman, Afoz; Popovic, Zoya

2004-01-01

As more assets are placed in orbit, opportunities emerge to combine various sets of satellites in temporary constellations to perform collaborative image collections. Often, new operations concepts for a satellite or set of satellites emerge after launch. To the degree with which new space assets can be inexpensively and rapidly integrated into temporary or "ad hoc" constellations, will determine whether these new ideas will be implemented or not. On the Earth Observing 1 (EO-1) satellite, a New Millennium Program mission, a number of experiments were conducted and are being conducted to demonstrate various aspects of an architecture that, when taken as a whole, will enable progressive mission autonomy. In particular, the target architecture will use adaptive ground antenna arrays to form, as close as possible, the equivalent of wireless access points for low earth orbiting satellites. Coupled with various ground and flight software and the Internet. the architecture enables progressive mission autonomy. Thus, new collaborative sensing techniques can be implemented post-launch. This paper will outline the overall operations concept and highlight details of both the research effort being conducted in

A Physical Validation Program for the GPM Mission

NASA Technical Reports Server (NTRS)

Smith, Eric A.

2003-01-01

The GPM mission is currently planned for start in the late 2007 - early 2008 time frame. Its main scientific goal is to help answer pressing scientific problems arising within the context of global and regional water cycling. These problems cut across a hierarchy of scales and include climate-water cycle interactions, techniques for improving weather and climate predictions, and better methods for combining observed precipitation with hydrometeorological prediction models for applications to hazardous flood-producing storms, seasonal flood draught conditions, and fresh water resource assessments. The GPM mission will expand the scope of precipitation measurement through the use of a constellation of some 9 satellites, one of which will be an advanced TRMM-like core satellite carrying a dual-frequency Ku-Ka band precipitation radar and an advanced, multifrequency passive microwave radiometer with vertical-horizontal polarization discrimination. The other constellation members will include new dedicated satellites and co-existing operational/research satellites carrying similar (but not identical) passive microwave radiometers. The goal of the constellation is to achieve approximately 3-hour sampling at any spot on the globe -- continuously. The constellation's orbit architecture will consist of a mix of sun-synchronous and non-sun-synchronous satellites with the core satellite providing measurements of cloud-precipitation microphysical processes plus calibration-quality rainrate retrievals to be used with the other retrieval information to ensure bias-free constellation coverage. A major requirement before the retrieved rainfall information generated by the GPM mission can be used effectively by prognostic models to improve weather forecasts, hydrometeorological forecasts, and climate model reanalysis simulations is a capability to quantify the error characteristics of the retrievals. A solution for this problem has been upheld in past precipitation missions because of the lack of suitable error modeling systems incorporated into the validation programs and data distribution systems. An overview of how NASA intends to overcome this problem for the GPM mission using a physically-based error modeling approach within a multi-faceted validation program is described. The solution is to first identify specific user requirements and then determine the most stringent of these requirements that embodies all essential error characterization information needed by the entire user community. In the context of NASA s scientific agenda for the GPM mission, the most stringent user requirement is found within the data assimilation community. The fundamental theory of data assimilation vis-a-vis ingesting satellite precipitation information into the pre-forecast initializations is based on quantifying the conditional bias and precision errors of individual rain retrievals, and the space-time structure of the precision error (i.e., the spatial-temporal error covariance). By generating the hardware and software capability to produce this information in a near real-time fashion, and to couple the derived quantitative error properties to the actual retrieved rainrates, all key validation users can be satisfied. The talk will describe the essential components of the hardware and software systems needed to generate such near real-time error properties, as well as the various paradigm shifts needed within the validation community to produce a validation program relevant to the precipitation user community.

GPM Mission Overview and U.S. Science Status

NASA Technical Reports Server (NTRS)

Hou, Arthur Y.; Azarbarzin, Art; Skofronick, Gail; Carlisle, Candace

2012-01-01

The Global Precipitation Measurement (GPM) Mission is an international satellite mission to unify and advance precipitation measurements from a constellation of research and operational sensors to provide "next-generation" precipitation products [1-2]. Water is fundamental to life on Earth. Knowing where and how much rain and snow falls globally is vital to understanding how weather and climate impact both our environment and Earth's water and energy cycles, including effects on agriculture, fresh water availability, and responses to natural disasters. Since rainfall and snowfall vary greatly from place to place and over time, satellites can provide more uniform observations of rain and snow around the globe than ground instruments, especially in areas where surface measurements are difficult. Relative to current global rainfall products, GPM data products will be characterized by: (l) more accurate instantaneous precipitation measurements (especially for light rain and cold-season solid precipitation), (2) more frequent sampling by an expanded constellation of domestic and international microwave radiometers including operational humidity sounders, (3) intercalibrated microwave brightness temperatures from constellation radiometers within a unified framework, and (4) physical-based precipitation retrievals from constellation radiometers using a common a priori cloud/hydrometeor database derived from GPM Core sensor measurements. The cornerstone of the GPM mission is the deployment of a Core Observatory in a unique 65 non-Sun-synchronous orbit to serve as a physics observatory and a reference standard to unify precipitation measurements by a constellation of dedicated and operational passive microwave sensors. The design of the GPM Core Observatory is an advancement of the Tropical Rainfall Measuring Mission (TRMM)'s highly successful rain-sensing package. The Core Observatory will carry a Ku/Ka-band Dual-frequency Precipitation Radar (DPR) and a multichannel (l0-183 GHz) GPM Microwave Radiometer (GMI). Since light rain and falling snow account for a significant fraction of precipitation occurrence in middle and high latitudes, the GPM instruments extend the capabilities of the TRMM sensors to detect falling snow, measure light rain, and provide, for the first time, quantitative estimates of microphysical properties of precipitation particles. The combined use of DPR and GMI measurements will place greater constraints on possible solutions to radiometer retrievals to improve the accuracy and consistency of precipitation retrievals from all constellation radiometers. The GMI uses 13 different microwave channels to observe energy from the different types of precipitation through clouds for estimating everything from heavy to light rain and for detecting falling snow. As the satellite passes over Earth, the GMI constantly scans a region 885 kilometers across. The Ball Aerospace and Technology Corporation built the GMI under contract with NASA Goddard Space Flight Center. The DPR provides three-dimensional information about precipitation particles derived from reflected energy by these particles at different heights within the cloud system. The two frequencies of the DPR also allow the radar to infer the sizes of precipitation particles and offer insights into a storm's physical characteristics. The Ka-band frequeny scans across a region of 125 kilometers and is nested within the wider scan of the Ku-band frequency of 245 kilometers. The Japan Aerospace and Exploration Agency (JAXA) and Japan's National Institute of Information and Communications Technology (NICT) built the DPR. The Core Observatory satellite will fly at an altitude of 253 miles (407 kilometers) in a non-Sun-synchronous orbit that covers the Earth from 65 S to 65 N - from about the Antarctic Circle to the Arctic Circle. The GPM Core Observatory is being developed and tested at NASA Goddard Space Flight Center. Once complete, a Japanese H-lIA rocket will carry thPM Core Observatory into orbit from Tanegashima Island, Japan in 2014. The GPM constellation is envisioned to comprise 8 or more microwave sensors provided by partners, including both conical imagers and cross-track sounders. GPM is currently a partnership between NASA and the Japan Aerospace Exploration Agency (JAXA). Additional partnerships are under development to include microwave radiometers on the French-Indian Megha-Tropiques satellite and U.S. Defense Meteorological Satellite Program (DMSP) satellites, as well as humidity sounders or precipitation sensors on operational satellites such as the National Polar-orbiting Operational Environmental Satellite System (NPOESS) Preparatory Project (NPP), NOAA-NASA Joint Polar Satellite System (JPSS) satellites, European MetOp satellites, and DMSP follow-on sensors. In addition, data from Chinese and Russian microwave radiometers may be available through international cooperation under the auspices of the Committee on Earth Observation Satellites (CEOS) and Group on Earth Observations (GEO). GPM's next-generation global precipitation data will lead to scientific advances and societal benefits in the following areas: (1) Improved knowledge of the Earth's water cycle and its link to climate change (2) New insights into precipitation microphysics, storm structures and large-scale atmospheric processes (3) Better understanding of climate sensitivity and feedback processes (4) Extended capabilities in monitoring and predicting hurricanes and other extreme weather events (5) Improved forecasting capabilities for natural hazards, including floods, droughts and landslides. (6) Enhanced numerical prediction skills for weather and climate (7) Better agricultural crop forecasting and monitoring of freshwater resources. An overview of the GPM mission concept and science activities in the United States, together with an update on international collaborations in radiometer intercalibration and ground validation, will be presented.

Origins of the "Western" Constellations

NASA Astrophysics Data System (ADS)

Frank, Roslyn M.

The development of the 48 Greek constellations is analyzed as a complex mixture of cognitive layers deriving from different cultural traditions and dating back to different epochs. The analysis begins with a discussion of the zodiacal constellations, goes on to discuss the stellar lore in Homer and Hesiod, and then examines several theories concerning the origins of the southern non-zodiacal constellations. It concludes with a commentary concerning the age and possible cultural significance of stars of the Great Bear constellation in light of ethnohistorical documentation, folklore, and beliefs related to European bear ceremonialism.

Optimal signal constellation design for ultra-high-speed optical transport in the presence of nonlinear phase noise.

PubMed

Liu, Tao; Djordjevic, Ivan B

2014-12-29

In this paper, we first describe an optimal signal constellation design algorithm suitable for the coherent optical channels dominated by the linear phase noise. Then, we modify this algorithm to be suitable for the nonlinear phase noise dominated channels. In optimization procedure, the proposed algorithm uses the cumulative log-likelihood function instead of the Euclidian distance. Further, an LDPC coded modulation scheme is proposed to be used in combination with signal constellations obtained by proposed algorithm. Monte Carlo simulations indicate that the LDPC-coded modulation schemes employing the new constellation sets, obtained by our new signal constellation design algorithm, outperform corresponding QAM constellations significantly in terms of transmission distance and have better nonlinearity tolerance.

The Integrated Medical Model: A Risk Assessment and Decision Support Tool for Space Flight Medical Systems

NASA Technical Reports Server (NTRS)

Kerstman, Eric; Minard, Charles; Saile, Lynn; deCarvalho, Mary Freire; Myers, Jerry; Walton, Marlei; Butler, Douglas; Iyengar, Sriram; Johnson-Throop, Kathy; Baumann, David

2009-01-01

The Integrated Medical Model (IMM) is a decision support tool that is useful to mission planners and medical system designers in assessing risks and designing medical systems for space flight missions. The IMM provides an evidence based approach for optimizing medical resources and minimizing risks within space flight operational constraints. The mathematical relationships among mission and crew profiles, medical condition incidence data, in-flight medical resources, potential crew functional impairments, and clinical end-states are established to determine probable mission outcomes. Stochastic computational methods are used to forecast probability distributions of crew health and medical resource utilization, as well as estimates of medical evacuation and loss of crew life. The IMM has been used in support of the International Space Station (ISS) medical kit redesign, the medical component of the ISS Probabilistic Risk Assessment, and the development of the Constellation Medical Conditions List. The IMM also will be used to refine medical requirements for the Constellation program. The IMM outputs for ISS and Constellation design reference missions will be presented to demonstrate the potential of the IMM in assessing risks, planning missions, and designing medical systems. The implementation of the IMM verification and validation plan will be reviewed. Additional planned capabilities of the IMM, including optimization techniques and the inclusion of a mission timeline, will be discussed. Given the space flight constraints of mass, volume, and crew medical training, the IMM is a valuable risk assessment and decision support tool for medical system design and mission planning.

Constellation of CubeSats for Realtime Ionospheric E-field Measurements for Global Space Weather

NASA Astrophysics Data System (ADS)

Crowley, G.; Swenson, C.; Pilinski, M.; Fish, C. S.; Neilsen, T. L.; Stromberg, E. M.; Azeem, I.; Barjatya, A.

2014-12-01

Inexpensive and robust space-weather monitoring instruments are needed to fill upcoming gaps in the Nation's ability to meet requirements for space weather specification and forecasting. Foremost among the needed data are electric fields, since they drive global ionospheric and thermospheric behavior, and because there are relatively few ground-based measurements. We envisage a constellation of CubeSats to provide global coverage of the electric field and its variability. The DICE (Dynamic Ionosphere CubeSat Experiment) mission was a step towards this goal, with two identical 1.5U CubeSats, each carrying three space weather instruments: (1) double probe instruments to measure AC and DC electric fields; (2) Langmuir probes to measure ionospheric electron density, and; (3) a magnetometer to measure field-aligned currents. DICE launched in October 2011. DICE was the first CubeSat mission to observe a Storm Enhanced Density event, fulfilling a major goal of the mission. Due to attitude control anomalies encountered in orbit, the DICE electric field booms have not yet been deployed. Important lessons have been learned for the implementation of a spin-stabilized CubeSat, and the design and performance of the Attitude Determination & Control System (ADCS). These lessons are now being applied to the DIME SensorSat, a risk-reduction mission that is capable of deploying flexible electric field booms up to a distance of 10-m tip-to-tip from a 1.5U CubeSat. DIME will measure AC and DC electric fields, and will exceed several IORD-2 threshold requirements. Ion densities, and magnetic fields will also be measured to characterize the performance of the sensor in different plasma environments. We show the utility of a constellation of electric field measurements, describe the DIME SensorSat, and demonstrate how the measurement will meet or exceed IORD requirements. The reduced cost of these sensors will enable constellations that can, for the first time, adequately resolve the spatial and temporal variability in ionospheric electrodynamics. DICE and DIME are collaborations between ASTRA and Space Dynamics Lab/Utah State University.

Gravity field recovery in the framework of a Geodesy and Time Reference in Space (GETRIS)

NASA Astrophysics Data System (ADS)

Hauk, Markus; Schlicht, Anja; Pail, Roland; Murböck, Michael

2017-04-01

The study ;Geodesy and Time Reference in Space; (GETRIS), funded by European Space Agency (ESA), evaluates the potential and opportunities coming along with a global space-borne infrastructure for data transfer, clock synchronization and ranging. Gravity field recovery could be one of the first beneficiary applications of such an infrastructure. This paper analyzes and evaluates the two-way high-low satellite-to-satellite-tracking as a novel method and as a long-term perspective for the determination of the Earth's gravitational field, using it as a synergy of one-way high-low combined with low-low satellite-to-satellite-tracking, in order to generate adequate de-aliasing products. First planned as a constellation of geostationary satellites, it turned out, that an integration of European Union Global Navigation Satellite System (Galileo) satellites (equipped with inter-Galileo links) into a Geostationary Earth Orbit (GEO) constellation would extend the capability of such a mission constellation remarkably. We report about simulations of different Galileo and Low Earth Orbiter (LEO) satellite constellations, computed using time variable geophysical background models, to determine temporal changes in the Earth's gravitational field. Our work aims at an error analysis of this new satellite/instrument scenario by investigating the impact of different error sources. Compared to a low-low satellite-to-satellite-tracking mission, results show reduced temporal aliasing errors due to a more isotropic error behavior caused by an improved observation geometry, predominantly in near-radial direction within the inter-satellite-links, as well as the potential of an improved gravity recovery with higher spatial and temporal resolution. The major error contributors of temporal gravity retrieval are aliasing errors due to undersampling of high frequency signals (mainly atmosphere, ocean and ocean tides). In this context, we investigate adequate methods to reduce these errors. We vary the number of Galileo and LEO satellites and show reduced errors in the temporal gravity field solutions for this enhanced inter-satellite-links. Based on the GETRIS infrastructure, the multiplicity of satellites enables co-estimating short-period long-wavelength gravity field signals, indicating it as powerful method for non-tidal aliasing reduction.

Modeling the plasmasphere based on LEO satellites onboard GPS measurements

NASA Astrophysics Data System (ADS)

Chen, Peng; Yao, Yibin; Li, Qinzheng; Yao, Wanqiang

2017-01-01

The plasmasphere, which is located above the ionosphere, is a significant component of Earth's atmosphere. A global plasmaspheric model was constructed using the total electron content (TEC) along the signal propagation path calculated using onboard Global Positioning System observations from the Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) and MetOp-A, provided by the COSMIC Data Analysis and Archive Center (CDAAC). First, the global plasmaspheric model was established using only COSMIC TEC, and a set of MetOp-A TEC provided by CDAAC served for external evaluation. Results indicated that the established model using only COSMIC data is highly accurate. Then, COSMIC and MetOp-A TEC were combined to produce a new global plasmaspheric model. Finally, the variational characteristics of global plasmaspheric electron content with latitude, local time, and season were investigated using the global plasmaspheric model established in this paper.

Research on TRMM and GPM Through Collaboration Between JAXA & NASA

NASA Technical Reports Server (NTRS)

Smith, Eric A.

2003-01-01

The Japan Aerospace Exploration Agency (JAXA) is conducting joint research with the Communications Research Laboratory (CRL) and the National Aeronautics and Space Administration (NASA) on a new constellation satellite observation project called Global Precipitation Measurement (GPM), the main satellite of which is planned for launch in 2008 by JAXA. This GPM project was proposed as a follow-up mission to the Tropical Rainfall Measuring Mission (TRMM) by both the Japanese and American sides based on the unparalleled scientific success of TRMM. A major reason for TRMM's success was the use of the worlds first spaceborne rain radar, the Precipitation Radar (PR) system developed by the National Space Development Agency of Japan (NASDA, now JAXA) and CRL. Measurements from this instrument have ushered in many new scientific findings and have opened a new era of precipitation measuring from space. GPM is an ambitious project which will produce accurate and frequent global observations of precipitation (both rain and snow) made possible by replacing TRMM with a new core satellite carrying an advanced radar-radiometer system, and serving as the centerpiece for a constellation of some eight (8) additional satellites being provided through international cooperation. The core satellite is to be flown up to high latitudes (inclined some 65-70 degrees), and will carry a dual-frequency precipitation radar (DPR) that will be newly developed by JAXA and CRL, along with a large aperture, extended frequency-range passive microwave radiometer being provided by NASA. Each constellation satellite will also carry some type of multi-channel passive microwave radiometer whose rain estimates will be calibrated and referenced to those made by the core satellite, producing for the first time fully-global, continuous, and bias-free precipitation datasets. GPM data will be delivered in near-realtime, taking a major step toward the operational use of precipitation information for model initialization and data assimilation in a number of application areas such as hazardous weather forecasting, flood warning, fresh water resource assessment, and crop growth prediction. In addition, GPM data will complement the now-existing global temperature record, allowing for improved assessments of climate change, particularly those processes in which the global water cycle both forces and responds to climatic drifts in global temperature conditions.

Soil Moisture Sensing Using Spaceborne GNSS Reflections: Comparison of CYGNSS Reflectivity to SMAP Soil Moisture

NASA Astrophysics Data System (ADS)

Chew, C. C.; Small, E. E.

2018-05-01

This paper quantifies the relationship between forward scattered L-band Global Navigation Satellite System (GNSS) signals, recorded by the Cyclone Global Navigation Satellite System (CYGNSS) constellation and Soil Moisture Active Passive (SMAP) soil moisture (SM). Although designed for tropical ocean surface wind sensing, the CYGNSS receivers also record GNSS reflections over land. The CYGNSS observations of reflection power are compared to SMAP SM between March 2017 and February 2018. A strong, positive linear relationship exists between changes in CYGNSS reflectivity and changes in SMAP SM, but not between the absolute magnitudes of the two observations. The sensitivity of CYGNSS reflectivity to SM varies spatially and can be used to convert reflectivity to estimates of SM. The unbiased root-mean-square difference between daily averaged CYGNSS-derived SM and SMAP SM is 0.045 cm3/cm3 and is similarly low between CYGNSS and in situ SM. These results show that CYGNSS, and future GNSS reflection missions, could provide global SM observations.

Men, monsters and the modern universe.

NASA Astrophysics Data System (ADS)

Lovi, G.; Tirion, W.

This book is intended to introduce to the constellations in a memorable way and to start looking at the sky's most easily observable objects with nothing more than the eyes or a pair of binoculars or a small telescope.

A medium-scale traveling ionospheric disturbance observed from the ground and from space

NASA Astrophysics Data System (ADS)

Dymond, K. F.; Watts, C.; Coker, C.; Budzien, S. A.; Bernhardt, P. A.; Kassim, N.; Lazio, T. J.; Weiler, K.; Crane, P. C.; Ray, P. S.; Cohen, A.; Clarke, T.; Rickard, L. J.; Taylor, G. B.; Schinzel, F.; Pihlstrom, Y.; Kuniyoshi, M.; Close, S.; Colestock, P.; Myers, S.; Datta, A.

2011-10-01

We report ultraviolet optical observations from space of a Medium-Scale Traveling Ionospheric Disturbance (MSTID) made during the Combined Radio Interferometry and COSMIC Experiment in Tomography Campaign (CRICKET) held on September 15, 2007 at ˜8:30 UT. The experiment used a Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC also known as FORMOSAT-3) satellite in conjunction with the Very Large Array (VLA) radio telescope, located near Socorro, NM, to study the ionosphere from the global scale down to the regional scale while the TIDs propagated through it. The COSMIC/FORMOSAT-3 satellite measured the F region electron density both horizontally and with altitude while the VLA measured the directions and speeds of the TIDs. These observations provide new information on this poorly understood class of TID and demonstrate the possibility of studying MSTIDs using space-based optical instruments.

CubeSat Integration into the Space Situational Awareness Architecture

NASA Astrophysics Data System (ADS)

Morris, K.; Wolfson, M.; Brown, J.

2013-09-01

Lockheed Martin Space Systems Company has recently been involved in developing GEO Space Situational Awareness architectures, which allows insights into how cubesats can augment the current national systems. One hole that was identified in the current architecture is the need for timelier metric track observations to aid in the chain of custody. Obtaining observations of objects at GEO can be supported by CubeSats. These types of small satellites are increasing being built and flown by government agencies like NASA and SMDC. CubeSats are generally mass and power constrained allowing for only small payloads that cannot typically mimic traditional flight capability. CubeSats do not have a high reliability and care must be taken when choosing mission orbits to prevent creating more debris. However, due to the low costs, short development timelines, and available hardware, CubeSats can supply very valuable benefits to these complex missions, affordably. For example, utilizing CubeSats for advanced focal plane demonstrations to support technology insertion into the next generation situational awareness sensors can help to lower risks before the complex sensors are developed. CubeSats can augment the planned ground and space based assets by creating larger constellations with more access to areas of interest. To aid in maintaining custody of objects, a CubeSat constellation at 500 km above GEO would provide increased point of light tracking that can augment the ground SSA assets. Key features of the Cubesat include a small visible camera looking along the GEO belt, a small propulsion system that allows phasing between CubeSats, and an image processor to reduce the data sent to the ground. An elegant communications network will also be used to provide commands to and data from multiple CubeSats. Additional CubeSats can be deployed on GSO launches or through ride shares to GEO, replenishing or adding to the constellation with each launch. Each CubeSat would take images of the GEO belt, process out the stars, and then downlink the data to the ground. This data can then be combined with the existing metric track data to enhance the coverage and timeliness. With the current capability of CubeSats and their payloads, along with the launch constraints, the near term focus is to integrate into existing architectures by reducing technology risks, understanding unique phenomenology, and augment mission collection capability. Understanding the near term benefits of utilizing CubeSats will better inform the SSA mission developers how to integrate CubeSats into the next generation of architectures from the start.

Observation impact studies with the Mercator Ocean analysis and forecasting systems

NASA Astrophysics Data System (ADS)

Remy, E. D.; Le Traon, P. Y.; Lellouche, J. M.; Drevillon, M.; Turpin, V.; Benkiran, M.

2016-02-01

Mercator Ocean produces and delivers in real-time ocean analysis and forecasts on a daily basis. The quality of the analysis highly relies on the availability and quality of the assimilated observations.Tools are developed to estimate the impact of the present network and to help designing the future evolutions of the observing systems in the context of near real time production of ocean analysis and forecasts. OSE and OSSE are the main approaches used in this context. They allow the assessment of the efficiency of a given data set to constrain the ocean model circulation through the data assimilation process. Illustrations will mainly focus on the present and future evolution of the Argo observation network and altimetry constellation, including the potential impact of future SWOT data. Our systems show clear sensitivities to observation array changes, mainly depending on the specified observation error and regional dynamic. Impact on non observed variables can be important and are important to evaluate. Dedicated diagnostics has to be define to measure the improvements bring by each data set. Alternative approaches to OSE and OSSE are also explored: approximate computation of DFS will be presented and discussed. Limitations of each approach will be discussed in the context of real time operation.

The Apollo Expericence Lessons Learned for Constellation Lunar Dust Management

NASA Astrophysics Data System (ADS)

Wagner, Sandra

2006-09-01

Lunar dust will present significant challenges to NASA's Lunar Exploration Missions. The challenges can be overcome by using best practices in system engineering design. For successful lunar surface missions, all systems that come into contact with lunar dust must consider the effects throughout the entire design process. Interfaces between all these systems with other systems also must be considered. Incorporating dust management into Concept of Operations and Requirements development are the best place to begin to mitigate the risks presented by lunar dust. However, that is only the beginning. To be successful, every person who works on NASA's Constellation lunar missions must be mindful of this problem. Success will also require fiscal responsibility. NASA must learn from Apollo the root cause of problems caused by dust, and then find the most cost-effective solutions to address each challenge. This will require a combination of common sense existing technologies and promising, innovative technical solutions

Structural Bus and Release Mechanisms on the ST5 Satellites: Summary and Status

NASA Technical Reports Server (NTRS)

Rossoni, Peter

2007-01-01

The Space Technology 5 Mechanical System met the challenge of packaging a fully functional science and technology satellite system with its Deployer mechanism into a compact 0.07cu m volume. Three 25 kg satellites were orbited in constellation in March, 2006. The ST5 mechanical system is composed of 1) The Structural Bus; 2) Magnetometer Instrument Boom 3) Spacecraft Deployer Release Mechanism This system includes a highly integrated electronics enclosure as a multifunctional structure; a lightweight, magnetically clean Magnetometer Boom; the first use of Nitinol Shape-Memory Alloy trigger devices for deploying multiple spacecraft; an innovative compliant mount for the umbilical connector and a Deployer mechanism that imparts both separation velocity and mission spin rate to three constellation flying satellites These elements employed cutting-edge design and analysis tools, state-of-the-art testing facilities and proven engineering techniques to meet stringent performance criteria, enabling the mission s success.

The Apollo Experience Lessons Learned for Constellation Lunar Dust Management

NASA Technical Reports Server (NTRS)

Wagner, Sandra

2006-01-01

Lunar dust will present significant challenges to NASA's Lunar Exploration Missions. The challenges can be overcome by using best practices in system engineering design. For successful lunar surface missions, all systems that come into contact with lunar dust must consider the effects throughout the entire design process. Interfaces between all these systems with other systems also must be considered. Incorporating dust management into Concept of Operations and Requirements development are the best place to begin to mitigate the risks presented by lunar dust. However, that is only the beginning. To be successful, every person who works on NASA's Constellation lunar missions must be mindful of this problem. Success will also require fiscal responsibility. NASA must learn from Apollo the root cause of problems caused by dust, and then find the most cost-effective solutions to address each challenge. This will require a combination of common sense existing technologies and promising, innovative technical solutions

Exploring with PAM: Prospecting ANTS Missions for Solar System Surveys

NASA Technical Reports Server (NTRS)

Clark, P. E.; Rilee, M. L.; Curtis, S. A.

2003-01-01

ANTS (Autonomous Nano-Technology Swarm), a large (1000 member) swarm of nano to picoclass (10 to 1 kg) totally autonomous spacecraft, are being developed as a NASA advanced mission concept. ANTS, based on a hierarchical insect social order, use an evolvable, self-similar, hierarchical neural system in which individual spacecraft represent the highest level nodes. ANTS uses swarm intelligence attained through collective, cooperative interactions of the nodes at all levels of the system. At the highest levels this can take the form of cooperative, collective behavior among the individual spacecraft in a very large constellation. The ANTS neural architecture is designed for totally autonomous operation of complex systems including spacecraft constellations. The ANTS (Autonomous Nano Technology Swarm) concept has a number of possible applications. A version of ANTS designed for surveying and determining the resource potential of the asteroid belt, called PAM (Prospecting ANTS Mission), is examined here.

Multiple continuous coverage of the earth based on multi-satellite systems with linear structure

NASA Astrophysics Data System (ADS)

Saulskiy, V. K.

2009-04-01

A new and wider definition is given to multi-satellite systems with linear structure (SLS), and efficiency of their application to multiple continuous coverage of the Earth is substantiated. Owing to this widening, SLS have incorporated already well-recognized “polar systems” by L. Rider and W.S. Adams, “kinematically regular systems” by G.V. Mozhaev, and “delta-systems” by J.G. Walker, as well as “near-polar systems” by Yu.P. Ulybyshev, and some other satellite constellations unknown before. A universal method of SLS optimization is presented, valid for any values of coverage multiplicity and the number of satellites in a system. The method uses the criterion of minimum radius of a circle seen from a satellite on the surface of the globe. Among the best SLS found in this way there are both systems representing the well-known classes mentioned above and new orbit constellations of satellites.

Demonstration of an efficient cooling approach for SBIRS-Low

NASA Astrophysics Data System (ADS)

Nieczkoski, S. J.; Myers, E. A.

2002-05-01

The Space Based Infrared System-Low (SBIRS-Low) segment is a near-term Air Force program for developing and deploying a constellation of low-earth orbiting observation satellites with gimbaled optics cooled to cryogenic temperatures. The optical system design and requirements present unique challenges that make conventional cooling approaches both complicated and risky. The Cryocooler Interface System (CIS) provides a remote, efficient, and interference-free means of cooling the SBIRS-Low optics. Technology Applications Inc. (TAI), through a two-phase Small Business Innovative Research (SBIR) program with Air Force Research Laboratory (AFRL), has taken the CIS from initial concept feasibility through the design, build, and test of a prototype system. This paper presents the development and demonstration testing of the prototype CIS. Prototype system testing has demonstrated the high efficiency of this cooling approach, making it an attractive option for SBIRS-Low and other sensitive optical and detector systems that require low-impact cryogenic cooling.

A miniature, low-power scientific fluxgate magnetometer: A stepping-stone to cube-satellite constellation missions

NASA Astrophysics Data System (ADS)

Miles, D. M.; Mann, I. R.; Ciurzynski, M.; Barona, D.; Narod, B. B.; Bennest, J. R.; Pakhotin, I. P.; Kale, A.; Bruner, B.; Nokes, C. D. A.; Cupido, C.; Haluza-DeLay, T.; Elliott, D. G.; Milling, D. K.

2016-12-01

Difficulty in making low noise magnetic measurements is a significant challenge to the use of cube-satellite (CubeSat) platforms for scientific constellation class missions to study the magnetosphere. Sufficient resolution is required to resolve three-dimensional spatiotemporal structures of the magnetic field variations accompanying both waves and current systems of the nonuniform plasmas controlling dynamic magnetosphere-ionosphere coupling. This paper describes the design, validation, and test of a flight-ready, miniature, low-mass, low-power, and low-magnetic noise boom-mounted fluxgate magnetometer for CubeSat applications. The miniature instrument achieves a magnetic noise floor of 150-200 pT/√Hz at 1 Hz, consumes 400 mW of power, has a mass of 121 g (sensor and boom), stows on the hull, and deploys on a 60 cm boom from a three-unit CubeSat reducing the noise from the onboard reaction wheel to less than 1.5 nT at the sensor. The instrument's capabilities will be demonstrated and validated in space in late 2016 following the launch of the University of Alberta Ex-Alta 1 CubeSat, part of the QB50 constellation mission. We illustrate the potential scientific returns and utility of using a CubeSats carrying such fluxgate magnetometers to constitute a magnetospheric constellation using example data from the low-Earth orbit European Space Agency Swarm mission. Swarm data reveal significant changes in the spatiotemporal characteristics of the magnetic fields in the coupled magnetosphere-ionosphere system, even when the spacecraft are separated by only approximately 10 s along track and approximately 1.4° in longitude.

Autonomy Architectures for a Constellation of Spacecraft

NASA Technical Reports Server (NTRS)

Barrett, Anthony

2000-01-01

Until the past few years, missions typically involved fairly large expensive spacecraft. Such missions have primarily favored using older proven technologies over more recently developed ones, and humans controlled spacecraft by manually generating detailed command sequences with low-level tools and then transmitting the sequences for subsequent execution on a spacecraft controller. This approach toward controlling a spacecraft has worked spectacularly on previous missions, but it has limitations deriving from communications restrictions - scheduling time to communicate with a particular spacecraft involves competing with other projects due to the limited number of deep space network antennae. This implies that a spacecraft can spend a long time just waiting whenever a command sequence fails. This is one reason why the New Millennium program has an objective to migrate parts of mission control tasks onboard a spacecraft to reduce wait time by making spacecraft more robust. The migrated software is called a "remote agent" and has 4 components: a mission manager to generate the high level goals, a planner/scheduler to turn goals into activities while reasoning about future expected situations, an executive/diagnostics engine to initiate and maintain activities while interpreting sensed events by reasoning about past and present situations, and a conventional real-time subsystem to interface with the spacecraft to implement an activity's primitive actions. In addition to needing remote planning and execution for isolated spacecraft, a trend toward multiple-spacecraft missions points to the need for remote distributed planning and execution. The past few years have seen missions with growing numbers of probes. Pathfinder has its rover (Sojourner), Cassini has its lander (Huygens), and the New Millenium Deep Space 3 (DS3) proposal involves a constellation of 3 spacecraft for interferometric mapping. This trend is expected to continue to progressively larger fleets. For example, one mission proposed to succeed DS3 would have 18 spacecraft flying in formation in order to detect earth-sized planets orbiting other stars. A proposed magnetospheric constellation would involve 5 to 500 spacecraft in Earth orbit to measure global phenomena within the magnetosphere. This work describes and compares three autonomy architectures for a system that continuously plans to control a fleet of spacecraft using collective mission goals instead of goals or command sequences for each spacecraft. A fleet of self-commanding spacecraft would autonomously coordinate itself to satisfy high level science and engineering goals in a changing partially-understood environment making feasible the operation of tens or even a hundred spacecraft (such as for interferometry or plasma physics missions). The easiest way to adapt autonomous spacecraft research to controlling constellations involves treating the constellation as a single spacecraft. Here one spacecraft directly controls the others as if they were connected. The controlling "master" spacecraft performs all autonomy reasoning, and the slaves only have real-time subsystems to execute the master's commands and transmit local telemetry/observations. The executive/diagnostics module starts actions and the master's real-time subsystem controls the action either locally or remotely through a slave. While the master/slave approach benefits from conceptual simplicity, it relies on an assumption that the master spacecraft's executive can continuously monitor the slaves' real-time subsystems, and this relies on high-bandwidth highly-reliable communications. Since unintended results occur fairly rarely, one way to relax the bandwidth requirements involves only monitoring unexpected events in spacecraft. Unfortunately, this disables the ability to monitor for unexpected events between spacecraft and leads to a host of coordination problems among the slaves. Also, failures in the communications system can result in losing slaves. The other two architectures improve robustness while reducing communications by progressively distributing more of the other three remote agent components across the constellation. In a teamwork architecture, all spacecraft have executives and real-time subsystems - only the leader has the planner/scheduler and mission manager. Finally, distributing all remote agent components leads to a peer-to-peer approach toward constellation control.

Tethered constellations

NASA Technical Reports Server (NTRS)

Lorenzini, E.

1986-01-01

The studies that have been carried out on Tethered Constellations are briefly addressed. A definition of a tethered constellation is any number of masses/platforms greater that two connected by tethers in a stable configuration. Configurations and stability constraints are reviewed. Conclusions reached are: (1) The 1-D, horizontal, passively stabilized constellations have been ruled out; (2) Fishbone constellations have been also ruled out; (3) Alternative stable 2-D configurations have been devised such as the quadrangular configuration stabilized by electrodynamic forces (ESC), the quadrangular configuration stabilized by differential air drag (DSC), and the pseudo elliptical configuration stabilized by electrodynamic forces (PEC). Typical dimensions for these constellations are 10 km (horizontal) by 20 km (vertical) with balloon diameters around 100 m in the case of a DSC and a power consumption around 7 KW for an ESC or PEC.

Fluxgate Magnetometry on the Experimental Albertan Satellite #1 (Ex-Alta-1) CubeSat Mission: Steps Toward a Magnetospheric Constellation Mission

NASA Astrophysics Data System (ADS)

Mann, I. R.; Miles, D.; Nokes, C.; Cupido, C.; Elliott, D.; Ciurzynski, M.; Barona, D.; Narod, B. B.; Bennest, J.; Pakhotin, I.; Kale, A.; Bruner, B.; Haluza-DeLay, T.; Forsyth, C.; Rae, J.; Lange, C.; Sameoto, D.; Milling, D. K.

2017-12-01

Making low noise magnetic measurements is a significant challenge to the use of cube-satellite (CubeSat) platforms for scientific constellation class missions for studies of geospace. We describe the design, validation, and test, and initial on-orbit results from a miniature, low-mass, low-power, and low-magnetic noise boom-mounted fluxgate magnetometer flown on the University of Alberta Experimental Albertan Satellite #1 (Ex-Alta-1) Cube Satellite, launched in 2017 from the International Space Station as part of the QB50 constellation mission. The miniature instrument achieves a magnetic noise floor of 150-200 pT/√Hz at 1 Hz, consumes 400 mW of power, has a mass of 121 g (sensor and boom), stows on the hull, and deploys on a 60 cm boom from a three-unit CubeSat reducing the noise from the onboard reaction wheel to less than 1.5 nT at the sensor. The instrument's capabilities are being demonstrated and validated in space with flight on Ex-Alta-1. We present on-orbit data from the boom-deployment and initial operations of the fluxgate sensor and illustrate the potential scientific returns and utility of using CubeSats carrying such fluxgate magnetometers to constitute a magnetospheric constellation mission. We further illustrate the value of scientific constellations using example data from the low-Earth orbit European Space Agency Swarm mission. Swarm data reveal significant changes in the spatiotemporal characteristics of the magnetic fields in the coupled magnetosphere-ionosphere system, even when the spacecraft are separated by only approximately 10 s along track and approximately 1.4° in longitude. This indicates the likely energetic significance of Alfven wave dynamics, and we use Swarm measurements to illustrate the value of satellite constellations for diagnosing magnetosphere-ionosphere coupling even in low-Earth orbit.

Typology of person-environment fit constellations: a platform addressing accessibility problems in the built environment for people with functional limitations.

PubMed

Slaug, Björn; Schilling, Oliver; Iwarsson, Susanne; Carlsson, Gunilla

2015-09-02

Making the built environment accessible for all regardless of functional capacity is an important goal for public health efforts. Considerable impediments to achieving this goal suggest the need for valid measurements of acccessibility and for greater attention to the complexity of person-environment fit issues. To address these needs, this study aimed to provide a methodological platform, useful for further research and instrument development within accessibility research. This was accomplished by the construction of a typology of problematic person-environment fit constellations, utilizing an existing methodology developed to assess and analyze accessibility problems in the built environment. By means of qualitative review and statistical methods we classified the person-environment fit components covered by an existing application which targets housing accessibility: the Housing Enabler (HE) instrument. The International Classification of Functioning, Disability and Health (ICF) was used as a conceptual framework. Qualitative classification principles were based on conceptual similarities and for quantitative analysis of similarities, Principal Component Analysis was carried out. We present a typology of problematic person-environment fit constellations classified along three dimensions: 1) accessibility problem range and severity 2) aspects of functioning 3) environmental context. As a result of the classification of the HE components, 48 typical person-environment fit constellations were recognised. The main contribution of this study is the proposed typology of person-environment fit constellations. The typology provides a methodological platform for the identification and quantification of problematic person-environment fit constellations. Its link to the globally accepted ICF classification system facilitates communication within the scientific and health care practice communities. The typology also highlights how relations between aspects of functioning and physical environmental barriers generate typical accessibility problems, and thereby furnishes a reference point for research oriented to how the built environment may be designed to be supportive for activity, participation and health.

Survey of Constellation-Era LOX/Methane Development Activities and Future Development Needs

NASA Technical Reports Server (NTRS)

Marshall, William M.; Stiegemeier, Benjamin; Greene, Sandra Elam; Hurlbert, Eric A.

2017-01-01

NASA formed the Constellation Program in 2005 to achieve the objectives of maintaining American presence in low-Earth orbit, returning to the moon for purposes of establishing an outpost, and laying the foundation to explore Mars and beyond in the first half of the 21st century. The Exploration Technology Development Program (ETDP) was formulated to address the technology needs to address Constellation architecture decisions. The Propellants and Cryogenic Advanced Development (PCAD) project was tasked with risk mitigation of specific propulsion related technologies to support ETDP. Propulsion systems were identified as critical technologies owing to the high gear-ratio of lunar Mars landers Cryogenic propellants offer performance advantage over storables (NTOMMH) Mass savings translate to greater payload capacity In-situ production of propellant an attractive feature; methane and oxygen identified as possible Martian in-situ propellants New technologies were required to meet more difficult missions High performance LOX/LH2 deep throttle descent engines High performance LOX/LCH4 ascent main and reaction control system (RCS) engines The PCAD project sought to provide those technologies through Reliable ignition pulse RCS Fast start High efficiency engines Stable deep throttling.

DOE Office of Scientific and Technical Information (OSTI.GOV)

G. CANAVAN

Space Based Interceptor (SBI) have ranges that are adequate to address rogue ICBMs. They are not overly sensitive to 30-60 s delay times. Current technologies would support boost phase intercept with about 150 interceptors. Higher acceleration and velocity could reduce than number by about a factor of 3 at the cost of heavier and more expensive Kinetic Kill Vehicles (KKVs). 6g SBI would reduce optimal constellation costs by about 35%; 8g SBI would reduce them another 20%. Interceptor ranges fall rapidly with theater missile range. Constellations increase significantly for ranges under 3,000 km, even with advanced interceptor technology. For distributedmore » launches, these estimates recover earlier strategic scalings, which demonstrate the improved absentee ratio for larger or multiple launch areas. Constellations increase with the number of missiles and the number of interceptors launched at each. The economic estimates above suggest that two SBI per missile with a modest midcourse underlay is appropriate. The SBI KKV technology would appear to be common for space- and surface-based boost phase systems, and could have synergisms with improved midcourse intercept and discrimination systems. While advanced technology could be helpful in reducing costs, particularly for short range theater missiles, current technology appears adequate for pressing rogue ICBM, accidental, and unauthorized launches.« less

Summary of Liquid Propulsion System Needs in Support of the Constellation Program

NASA Technical Reports Server (NTRS)

Lorier, Terry; Sumrall, Phil; Baine, Michael

2008-01-01

In January 2004, the President of the United States established the Vision for Space Exploration (VSE) to complete the International Space Station, retire the Space Shuttle and develop its replacement, and expand the human presence on the Moon as a stepping stone to human exploration of Mars and worlds beyond. In response, NASA developed the Constellation Program, consisting of the components shown in Figure 1. This paper will summarize the manned spaceflight liquid propulsion system needs in support of the Constellation Program over the next 10 years. It will address all liquid engine needs to support human exploration from low Earth orbit (LEO) to the lunar surface, including an overview of engines currently under contract, those baselined but not yet under contract, and those propulsion needs that have yet to be initiated. There may be additional engine needs for early demonstrators, but those will not be addressed as part of this paper. Also, other portions of the VSE architecture, including the planned Orion abort test boosters and the Lunar Precursor Robotic Program, are not addressed here as they either use solid motors or are focused on unmanned elements of returning humans to the Moon.

Surface Landing Site Weather Analysis for NASA's Constellation Program

NASA Technical Reports Server (NTRS)

Altino, Karen M.; Burns, K. L.

2008-01-01

Weather information is an important asset for NASA's Constellation Program in developing the next generation space transportation system to fly to the International Space Station, the Moon and, eventually, to Mars. Weather conditions can affect vehicle safety and performance during multiple mission phases ranging from pre-launch ground processing of the Ares vehicles to landing and recovery operations, including all potential abort scenarios. Meteorological analysis is art important contributor, not only to the development and verification of system design requirements but also to mission planning and active ground operations. Of particular interest are the surface weather conditions at both nominal and abort landing sites for the manned Orion capsule. Weather parameters such as wind, rain, and fog all play critical roles in the safe landing of the vehicle and subsequent crew and vehicle recovery. The Marshall Space Flight Center (MSFC) Natural Environments Branch has been tasked by the Constellation Program with defining the natural environments at potential landing zones. This paper wiI1 describe the methodology used for data collection and quality control, detail the types of analyses performed, and provide a sample of the results that cab be obtained.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thorpe, J. I.; Livas, J.; Maghami, P.

Arm locking is a proposed laser frequency stabilization technique for the Laser Interferometer Space Antenna (LISA), a gravitational-wave observatory sensitive in the milliHertz frequency band. Arm locking takes advantage of the geometric stability of the triangular constellation of three spacecraft that compose LISA to provide a frequency reference with a stability in the LISA measurement band that exceeds that available from a standard reference such as an optical cavity or molecular absorption line. We have implemented a time-domain simulation of a Kalman-filter-based arm-locking system that includes the expected limiting noise sources as well as the effects of imperfect a priorimore » knowledge of the constellation geometry on which the design is based. We use the simulation to study aspects of the system performance that are difficult to capture in a steady-state frequency-domain analysis such as frequency pulling of the master laser due to errors in estimates of heterodyne frequency. We find that our implementation meets requirements on both the noise and dynamic range of the laser frequency with acceptable tolerances and that the design is sufficiently insensitive to errors in the estimated constellation geometry that the required performance can be maintained for the longest continuous measurement intervals expected for the LISA mission.« less

KSC-2009-5342

NASA Image and Video Library

2009-10-06

CAPE CANAVERAL, Fla. – A banner inside NASA Kennedy Space Center's Vehicle Assembly Building captures the excitement building at Kennedy in anticipation of the flight test of the Ares I-X rocket, towering above it in High Bay 3. Part of the Constellation Program, the Ares I-X is the test vehicle for the Ares I, which is the essential core of a space transportation system designed to carry crewed missions back to the moon, on to Mars and out into the solar system. The Ares I-X flight test is targeted for Oct. 27. For information on the Ares I-X vehicle and flight test, visit http://www.nasa.gov/mission_pages/constellation/ares/flighttests/aresIx/index.html. Photo credit: NASA/Glenn Benson

Real-Time GNSS Positioning with JPL's new GIPSYx Software

NASA Astrophysics Data System (ADS)

Bar-Sever, Y. E.

2016-12-01

The JPL Global Differential GPS (GDGPS) System is now producing real-time orbit and clock solutions for GPS, GLONASS, BeiDou, and Galileo. The operations are based on JPL's next generation geodetic analysis and data processing software, GIPSYx (also known at RTGx). We will examine the impact of the nascent GNSS constellations on real-time kinematic positioning for earthquake monitoring, and assess the marginal benefits from each constellation. We will discus the options for signal selection, inter-signal bias modeling, and estimation strategies in the context of real-time point positioning. We will provide a brief overview of the key features and attributes of GIPSYx. Finally we will describe the current natural hazard monitoring services from the GDGPS System.

Design and operation of SUCHI: the space ultra-compact hyperspectral imager for a small satellite

NASA Astrophysics Data System (ADS)

Crites, S. T.; Lucey, P. G.; Wright, R.; Chan, J.; Garbeil, H.; Horton, K. A.; Imai, A.; Pilger, E. J.; Wood, M.; Yoneshige, Lance

2014-06-01

The primary payload on the University of Hawaii-built `HiakaSat' micro-satellite will be the Space Ultra Compact Hyperspectral Imager (SUCHI). SUCHI is a low-mass (<9kg), low-volume (10x10x36 cm3) long wave infrared hyperspectral imager designed and built at the University of Hawaii. SUCHI is based on a variable-gap Fabry-Perot interferometer employed as a Fourier transform spectrometer with images collected by a commercial 320x256 microbolometer array. The microbolometer camera and vacuum-sensitive electronics are contained within a sealed vessel at 1 atm. SUCHI will collect spectral radiance data from 8 to 14 microns and demonstrate the potential of this instrument for geological studies from orbit (e.g. mapping of major rock-forming minerals) and volcanic hazard observation and assessment (e.g. quantification of volcanic sulfur dioxide pollution and lava flow cooling rates). The sensor has been integrated with the satellite which will launch on the Office of Responsive Space ORS-4 mission scheduled for 2014. The primary mission will last 6 months, with extended operations anticipated for approximately 2 years. A follow-on mission has been proposed to perform imaging of Earth's surface in the 3-5 micron range with a field of view of 5 km with 5.25 m sampling (from a 350 km orbit). The 19-kg proposed instrument will be a prototype sensor for a constellation of small satellites for Earth imaging. The integrated satellite properties will be incorporated into the Hawaii Space Flight Laboratory's constellation maintenance software environment COSMOS (Comprehensive Openarchitecture Space Mission Operations System) to ease future implementation of the instrument as part of a constellation.

The NASA ISS-RapidScat Mission (Invited)

NASA Astrophysics Data System (ADS)

Rodriguez, E.

2013-12-01

After NASA's QuikSCAT satellite stopped spinning on November 2009, an observational gap opened in the international ocean surface winds constellation of observing satellites that also includes EUMETSAT's ASCAT and ISRO's OSCAT. While QuikSCAT continues to provide calibration data to the ISRO OSCAT on OceanSat-2 scatterometer, these data are sorely limited due to the satellite's hampered capabilities. Recognizing this gap, NASA has put together in a matter of a few months the ISS-RapidScat mission, which is a partnership between JPL, the ISS, ESA, KSC, and SpaceX. This mission, expected to launch in spring of 2014, is a very low-cost mission, enabled by the creative use of spare parts and a very rapid development process that nevertheless has great benefit to the science and operational weather and marine support communities. Since it uses the QuikSCAT engineering model, the RapidScat data will be quite similar to QuikSAT's in terms of data quality and spatial resolution, although modest gains in the latter are foreseen. However, due to the lower orbit and inclination, the RapidScat swath will be approximately a factor of two smaller than QuikSCAT's, and its geographic coverage will be limited to latitudes smaller than about 55 deg. Nevertheless, the unique sampling capabilities of the ISS non-sun-synchronous orbit opens up new science applications not available for typical sun-synchronous scatterometers. Foremost among these, is the ability to provide many more data that are collocated in space and time with each of the satellites in the international scatterometer constellation. Sun-synchronous satellites typically see each other with a suitably small temporal separation at high latitudes, and therefore, cross-calibration is limited in terms of the conditions that occur. RapidScat's orbit enables coincident wind observations in nearly every orbit, with a global geographical distribution, which will enable the determination of the global patterns of wind biases between all satellites in the constellation. Of great interest as well will be the ability of RapidScat to observe both the diurnal and semi-diurnal wind cycles. Previously, the diurnal cycle had been partially observed by combining scatterometer pairs, but its seasonal and yearly changes had not been characterized. Due to relative biases, the semi-diurnal cycle has not been observed from space. RapidScat will also be able to observed the diurnal cycle over land, which will improve the knowledge of scatterometer calibration targets and complement soil moisture and vegetation missions. Finally, although it has a smaller swath than QuikSCAT's, RapidScat's data will serve as a useful complement to the winds acquired from other platforms. This may be of significant advantage when covering rapidly developing systems, such as tropical hurricanes.

Advanced Lithium-Ion Cell Development for NASA's Constellation Missions

NASA Technical Reports Server (NTRS)

Reid, Concha M.; Miller, Thomas B.; Manzo, Michelle A.; Mercer, Carolyn R.

2008-01-01

The Energy Storage Project of NASA s Exploration Technology Development Program is developing advanced lithium-ion batteries to meet the requirements for specific Constellation missions. NASA GRC, in conjunction with JPL and JSC, is leading efforts to develop High Energy and Ultra High Energy cells for three primary Constellation customers: Altair, Extravehicular Activities (EVA), and Lunar Surface Systems. The objective of the High Energy cell development is to enable a battery system that can operationally deliver approximately 150 Wh/kg for 2000 cycles. The Ultra High Energy cell development will enable a battery system that can operationally deliver 220 Wh/kg for 200 cycles. To accomplish these goals, cathode, electrolyte, separator, and safety components are being developed for High Energy Cells. The Ultra High Energy cell development adds lithium alloy anodes to the component development portfolio to enable much higher cell-level specific energy. The Ultra High Energy cell development is targeted for the ascent stage of Altair, which is the Lunar Lander, and for power for the Portable Life support System of the EVA Lunar spacesuit. For these missions, mass is highly critical, but only a limited number of cycles are required. The High Energy cell development is primarily targeted for Mobility Systems (rovers) for Lunar Surface Systems, however, due to the high risk nature of the Ultra High Energy cell development, the High Energy cell will also serve as a backup technology for Altair and EVA. This paper will discuss mission requirements and the goals of the material, component, and cell development efforts in further detail.

New vision solar system mission study: Use of space reactor bimodal system with microspacecraft to determine origin and evolution of the outer plants in the solar system

NASA Technical Reports Server (NTRS)

Mondt, Jack F.; Zubrin, Robert M.

1996-01-01

The vision for the future of the planetary exploration program includes the capability to deliver 'constellations' or 'fleets' of microspacecraft to a planetary destination. These fleets will act in a coordinated manner to gather science data from a variety of locations on or around the target body, thus providing detailed, global coverage without requiring development of a single large, complex and costly spacecraft. Such constellations of spacecraft, coupled with advanced information processing and visualization techniques and high-rate communications, could provide the basis for development of a 'virtual presence' in the solar system. A goal could be the near real-time delivery of planetary images and video to a wide variety of users in the general public and the science community. This will be a major step in making the solar system accessible to the public and will help make solar system exploration a part of the human experience on Earth.

RapidEye constellation relative radiometric accuracy measurement using lunar images

NASA Astrophysics Data System (ADS)

Steyn, Joe; Tyc, George; Beckett, Keith; Hashida, Yoshi

2009-09-01

The RapidEye constellation includes five identical satellites in Low Earth Orbit (LEO). Each satellite has a 5-band (blue, green, red, red-edge and near infrared (NIR)) multispectral imager at 6.5m GSD. A three-axes attitude control system allows pointing the imager of each satellite at the Moon during lunations. It is therefore possible to image the Moon from near identical viewing geometry within a span of 80 minutes with each one of the imagers. Comparing the radiometrically corrected images obtained from each band and each satellite allows a near instantaneous relative radiometric accuracy measurement and determination of relative gain changes between the five imagers. A more traditional terrestrial vicarious radiometric calibration program has also been completed by MDA on RapidEye. The two components of this program provide for spatial radiometric calibration ensuring that detector-to-detector response remains flat, while a temporal radiometric calibration approach has accumulated images of specific dry dessert calibration sites. These images are used to measure the constellation relative radiometric response and make on-ground gain and offset adjustments in order to maintain the relative accuracy of the constellation within +/-2.5%. A quantitative comparison between the gain changes measured by the lunar method and the terrestrial temporal radiometric calibration method is performed and will be presented.

Does the Constellation Program Offer Opportunities to Achieve Space Science Goals in Space?

NASA Technical Reports Server (NTRS)

Thronson, Harley A.; Lester, Daniel F.; Dissel, Adam F.; Folta, David C.; Stevens, John; Budinoff, Jason G.

2008-01-01

Future space science missions developed to achieve the most ambitious goals are likely to be complex, large, publicly and professionally very important, and at the limit of affordability. Consequently, it may be valuable if such missions can be upgraded, repaired, and/or deployed in space, either with robots or with astronauts. In response to a Request for Information from the US National Research Council panel on Science Opportunities Enabled by NASA's Constellation System, we developed a concept for astronaut-based in-space servicing at the Earth-Moon L1,2 locations that may be implemented by using elements of NASA's Constellation architecture. This libration point jobsite could be of great value for major heliospheric and astronomy missions operating at Earth-Sun Lagrange points. We explored five alternative servicing options that plausibly would be available within about a decade. We highlight one that we believe is both the least costly and most efficiently uses Constellation hardware that appears to be available by mid-next decade: the Ares I launch vehicle, Orion/Crew Exploration Vehicle, Centaur vehicle, and an airlock/servicing node developed for lunar surface operations. Our concept may be considered similar to the Apollo 8 mission: a valuable exercise before descent by astronauts to the lunar surface.

NASA Tropospheric Composition Program field campagins as prototypes to advance the Integrated Observing System for Air Quality

NASA Astrophysics Data System (ADS)

Lefer, B. L.; Crawford, J. H.; Pierce, R. B.; Berkoff, T.; Swap, R.; Janz, S. J.; Ahn, J.; Al-Saadi, J. A.

2017-12-01

With the launch over the virtual constellation of earth observing satellites for atmospheric composition (e.g., TROPOMI, GEMS, TEMPO, and Sentinel-4) over the next several years, we have a unique opportunity to develop an Integrated Observing System (IOS) for air quality in the northern hemisphere. Recently, NASA's Tropospheric Composition Program (TCP) has participated in several different air quality related field campaigns as an effort to explore various prototypes of the IOS for Air Quality. The IOS for air quality could be a system were space-based observations of air quality (generally, column abundances of NO2, HCHO, O3, SO2, and AOD) are given added "value" by being integrated with: a) long-term ground-based observations;b) regional and global air quality and chemical transport models; as well as c) measurements from targeted airborne field campaigns. The recent Korea-US Air Quality Study (KORUS-AQ), the Lake Michigan Ozone Study 2017 (LMOS), and the Ozone Water-Land Environmental Transition Study (OWLETS) field campaigns were held in different locations and made measurements over different scale. However, all of these provide an opportunity to learn about how a future integrated air quality observing system can be implemented to serve a variety of air quality related objectives. NASA TCP is also exploring enchancements to our routine observations to strengthen the IOS for air quality in the future.

Proceedings of a Workshop on the Applications of Tethers in Space, Volume 1

NASA Technical Reports Server (NTRS)

1983-01-01

Project overview; tether deployment; satellite system description; tether fundamentals; science applications; electrodynamic interactions; transportation; artificial gravity; and constellations; were described.

A New Paradigm in Earth Environmental Monitoring with the CYGNSS Small Satellite Constellation.

PubMed

Ruf, Christopher S; Chew, Clara; Lang, Timothy; Morris, Mary G; Nave, Kyle; Ridley, Aaron; Balasubramaniam, Rajeswari

2018-06-08

A constellation of small, low-cost satellites is able to make scientifically valuable measurements of the Earth which can be used for weather forecasting, disaster monitoring, and climate studies. Eight CYGNSS satellites were launched into low Earth orbit on December 15, 2016. Each satellite carries a science radar receiver which measures GPS signals reflected from the Earth surface. The signals contain information about the surface, including wind speed over ocean, and soil moisture and flooding over land. The satellites are distributed around their orbit plane so that measurements can be made more often to capture extreme weather events. Innovative engineering approaches are used to reduce per satellite cost, increase the number in the constellation, and improve temporal sampling. These include the use of differential drag rather than propulsion to adjust the spacing between satellites and the use of existing GPS signals as the science radars' transmitter. Initial on-orbit results demonstrate the scientific utility of the CYGNSS observations, and suggest that a new paradigm in spaceborne Earth environmental monitoring is possible.

Hyperspectral Cubesat Constellation for Natural Hazard Response

NASA Technical Reports Server (NTRS)

Mandl, Daniel; Crum, Gary; Ly, Vuong; Handy, Matthew; Huemmrich, Karl F.; Ong, Lawrence; Holt, Ben; Maharaja, Rishabh

2016-01-01

The authors on this paper are team members of the Earth Observing 1 (E0-1) mission which has flown an imaging spectrometer (hyperspectral) instrument called Hyperion for the past 15+ years. The satellite is able to image any spot on Earth in the nadir looking direction every 16 days and with slewing, of the satellite for up to a 23 degree view angle, any spot on the Earth can be imaged approximately every 2 to 3 days. EO-1 has been used to track many natural hazards such as wildfires, volcanoes and floods. An enhanced capability that has been sought is the ability to image natural hazards in a daily time series for space-based imaging spectrometers. The Hyperion cannot provide this capability on EO-1 with the present polar orbit. However, a constellation of cubesats, each with the same imaging spectrometer, positioned strategically can be used to provide daily coverage or even diurnal coverage, cost-effectively. This paper sought to design a cubesat constellation mission that would accomplish this goal and then to articulate the key tradeoffs.

Evidence for Strange Stellar Family Artist Concept

NASA Image and Video Library

2007-07-24

This artist concept based on data from NASA Spitzer Space Telescope, depicts a quadruple-star system called HD 98800. The system is approximately 10 million years old, and is located 150 light-years away in the constellation TW Hydrae.

Simulation of a Lunar Surface Base Power Distribution Network for the Constellation Lunar Surface Systems

NASA Technical Reports Server (NTRS)

Mintz, Toby; Maslowski, Edward A.; Colozza, Anthony; McFarland, Willard; Prokopius, Kevin P.; George, Patrick J.; Hussey, Sam W.

2010-01-01

The Lunar Surface Power Distribution Network Study team worked to define, breadboard, build and test an electrical power distribution system consistent with NASA's goal of providing electrical power to sustain life and power equipment used to explore the lunar surface. A testbed was set up to simulate the connection of different power sources and loads together to form a mini-grid and gain an understanding of how the power systems would interact. Within the power distribution scheme, each power source contributes to the grid in an independent manner without communication among the power sources and without a master-slave scenario. The grid consisted of four separate power sources and the accompanying power conditioning equipment. Overall system design and testing was performed. The tests were performed to observe the output and interaction of the different power sources as some sources are added and others are removed from the grid connection. The loads on the system were also varied from no load to maximum load to observe the power source interactions.

NASA Constellation Distributed Simulation Middleware Trade Study

NASA Technical Reports Server (NTRS)

Hasan, David; Bowman, James D.; Fisher, Nancy; Cutts, Dannie; Cures, Edwin Z.

2008-01-01

This paper presents the results of a trade study designed to assess three distributed simulation middleware technologies for support of the NASA Constellation Distributed Space Exploration Simulation (DSES) project and Test and Verification Distributed System Integration Laboratory (DSIL). The technologies are the High Level Architecture (HLA), the Test and Training Enabling Architecture (TENA), and an XML-based variant of Distributed Interactive Simulation (DIS-XML) coupled with the Extensible Messaging and Presence Protocol (XMPP). According to the criteria and weights determined in this study, HLA scores better than the other two for DSES as well as the DSIL.

A Stable Clock Error Model Using Coupled First and Second Order Gauss-Markov Processes

NASA Technical Reports Server (NTRS)

Carpenter, Russell; Lee, Taesul

2008-01-01

Long data outages may occur in applications of global navigation satellite system technology to orbit determination for missions that spend significant fractions of their orbits above the navigation satellite constellation(s). Current clock error models based on the random walk idealization may not be suitable in these circumstances, since the covariance of the clock errors may become large enough to overflow flight computer arithmetic. A model that is stable, but which approximates the existing models over short time horizons is desirable. A coupled first- and second-order Gauss-Markov process is such a model.

COMPASS Final Report: Lunar Network Satellite-High Rate (LNS-HR)

NASA Technical Reports Server (NTRS)

oleson, Steven R.; McGuire, Melissa L.

2012-01-01

Two design options were explored to address the requirement to provide lunar piloted missions with continuous communications for outpost and sortie missions. Two unique orbits were assessed, along with the appropriate spacecraft (S/C) to address these requirements. Both constellations (with only two S/C each) provide full time coverage (24 hr/7 d) for a south polar base and also provide continuous 7 day coverage for sorties for specified sites and periodic windows. Thus a two-satellite system can provide full coverage for sorties for selected windows of opportunity without reconfiguring the constellation.

Monitoring of Arctic Conditions from a Virtual Constellation of Synthetic Aperture Radar Satellites

DTIC Science & Technology

2014-09-30

Constellation of Synthetic Aperture Radar Satellites RSMAS – Department of Ocean Sciences Center for Southeastern Tropical Advanced Remote Sensing...fax: (305) 421-4696 email: pminnett@rsmas.miami.edu Award Number: N00014-12-1-0448 LONG-TERM GOALS Utilize a constellation of satellite...OBJECTIVES a) Provide daily Arctic situational awareness from the CSTARS SAR satellite constellation . b) Develop a Neural Network algorithm for ice-type

The CEOS/GEO Constellation Concept

NASA Technical Reports Server (NTRS)

Cramer, Bryant; Ungar, Stephen

2007-01-01

The Constellation concept was first proposed during a discussion at the 19th CEOS Plenary, in London, in November 2005. The first Paper of the Constellation Concept was presented at the CEOS Strategic Implementation Team meeting (SIT-18), in Frascati, in March 2006, and strongly endorsed by the CEOS Principals. The concept attempts to provide agencies with tools for implementation of the elements that have been previously discussed in international forums (GEO Work Plan, GCOS Implementation Plan). This provides a solid foundation from the community providing requirements. Though agency spending is governed by national requirements, CEOS seeks synergies among member agency programs to fulfil GEOSS requirements, defining guidelines and standards to help agencies to determine from the outset what can be achieved. The constellations concept will allow the development of a commonalties approach among different agencies. At the heart of the application of the Constellations concept is the definition of a series of standards (specific to each Constellation) - required to be satisfied for any mission to be included in the constellation - and a process of recognition/acceptance, whereby an agency applies to SIT to have one or more of its missions (ideally from the outset of planning) recognised as meeting the constellation standards and thereby satisfying the relevant user community needs.

An Interdisciplinary Approach at Studying the Earth-Sun System with GPS/GNSS and GPS-like Signals

NASA Technical Reports Server (NTRS)

Zuffada, Cinzia; Hajj, George; Mannucci, Anthony J.; Chao, Yi; Ao, Chi; Zumberge, James

2005-01-01

The value of Global Positioning Satellites (GPS) measurements to atmospheric science, space physics, and ocean science, is now emerging or showing a potential to play a major role in the evolving programs of NASA, NSF and NOAA. The objective of this communication is to identify and articulate the key scientific questions that are optimally, or perhaps uniquely, addressed by GPS or GPS-like observations, and discuss their relevance to existing or planned national Earth-science research programs. The GPS-based ocean reflection experiments performed to date have demonstrated the precision and spatial resolution suitable to altimetric applications that require higher spatial resolution and more frequent repeat than the current radar altimeter satellites. GPS radio occultation is promising as a climate monitoring tool because of its benchmark properties: its raw observable is based on extremely accurate timing measurements. GPS-derived temperature profiles can provide meaningful climate trend information over decadal time scales without the need for overlapping missions or mission-to-mission calibrations. By acquiring data as GPS satellites occult behind the Earth's limb, GPS also provides high vertical resolution information on the vertical structure of electron density with global coverage. New experimental techniques will create more comprehensive TEC maps by using signals reflected from the oceans and received in orbit. This communication will discuss a potential future GNSS Earth Observing System project which would deploy a constellation of satellites using GPS and GPS-like measurements, to obtain a) topography measurements based on GPS reflections with an accuracy and horizontal resolution suitable for eddy monitoring, and h) climate-records quality atmospheric temperature profiles. The constellation would also provide for measurements of ionospheric elec tron density. This is a good example of an interdisciplinary mission concept, with broad science objectives of high societal relevance, al l resting on common cost-effective technology.

The extratropical transition of Tropical Storm Cindy from a GLM, ISS LIS and GPM perspective

NASA Astrophysics Data System (ADS)

Heuscher, L.; Gatlin, P. N.; Petersen, W. A.; Liu, C.; Cecil, D. J.

2017-12-01

The distribution of lightning with respect to tropical convective precipitation systems has been well established in previous studies, and more recently by the successful Tropical Rainfall Measuring Mission (TRMM). However, TRMM did not provide information about precipitation features pole-ward of ±38° latitude. Hence not much is known about the evolution of lightning within extra-tropical cyclones traversing the mid-latitudes, especially its oceans. To facilitate such studies we have combined lightning data from the Geostationary Lightning Mapper (GLM) onboard GOES-16 and the Lightning Imaging Sensor (LIS) onboard the International Space Station (ISS) together with precipitation features obtained from the Global Precipitation Measurement (GPM) mission constellation of satellites. We used this lightning-enriched precipitation feature dataset to investigate the lightning and precipitation characteristics of Tropical Storm Cindy (20 June - 24 June 2017) from its organization in the central Gulf of Mexico to its landfall along the northern Gulf and transition to an extra-tropical cyclone. We analyzed lightning observations from GLM and ISS LIS in relation to microwave brightness temperatures from GPM constellation satellite overpasses of Cindy. We find that the 37 and 89 GHz brightness temperatures decreased as Cindy strengthened and continued to decrease after landfall and as Cindy took on more baroclinic characteristics during which time its overall lightning activity increased by a factor of six. In this regard, the study provides a new observationally-based view of the tropical to extra-tropical transition and its impact on lightning production.

The Mathematics of the Global Positioning System.

ERIC Educational Resources Information Center

Nord, Gail D.; Jabon, David; Nord, John

1997-01-01

Presents an activity that illustrates the application of mathematics to modern navigation and utilizes the Global Positioning System (GPS). GPS is a constellation of 24 satellites that enables receivers to compute their position anywhere on the earth with great accuracy. (DDR)

Improving Database Simulations for Bayesian Precipitation Retrieval using Non-Spherical Ice Particles

NASA Astrophysics Data System (ADS)

Ringerud, S.; Skofronick Jackson, G.; Kulie, M.; Randel, D.

2016-12-01

NASA's Global Precipitation Measurement Mission (GPM) provides a wealth of both active and passive microwave observations aimed at furthering understanding of global precipitation and the hydrologic cycle. Employing a constellation of passive microwave radiometers increases global coverage and sampling, while the core satellite acts as a transfer standard, enabling consistent retrievals across individual constellation members. The transfer standard is applied in the form of a physically based a priori database constructed for use in Bayesian retrieval algorithms for each radiometer. The database is constructed using hydrometeor profiles optimized for the best fit to simultaneous active/passive core satellite measurements via the GPM Combined Algorithm. Initial validation of GPM rainfall products using the combined database suggests high retrieval errors for convective precipitation over land and at high latitudes. In such regimes, the signal from ice scattering observed at the higher microwave frequencies becomes particularly important for detecting and retrieving precipitation. For cross-track sounders such as MHS and SAPHIR, this signal is crucial. It is therefore important that the scattering signals associated with precipitation are accurately represented and modeled in the retrieval database. In the current GPM combined retrieval and constellation databases, ice hydrometeors are represented as "fluffy spheres", with assumed density and scattering parameters calculated using Mie theory. Resulting simulated Tb agree reasonably well at frequencies up to 89 GHz, but show significant biases at higher frequencies. In this work the database is recreated using an ensemble of non-spherical ice particles with single scattering properties calculated using discrete dipole approximation. Simulated Tb agreement is significantly improved across the high frequencies, decreasing biases by an order of magnitude in several of the channels. The new database is applied for a sample of GPM constellation retrievals and the retrieved precipitation rates compared, to demonstrate areas where the use of more complex ice particles will have the greatest effect upon the final retrievals.

Regionalized Lunar South Pole Surface Navigation System Analysis

NASA Technical Reports Server (NTRS)

Welch, Bryan W.

2008-01-01

Apollo missions utilized Earth-based assets for navigation because the landings took place at lunar locations in constant view from the Earth. The new exploration campaign to the lunar south pole region will have limited Earth visibility, but the extent to which a navigation system comprised solely of Earth-based tracking stations will provide adequate navigation solutions in this region is unknown. This report presents a dilution-of-precision (DoP)-based, stationary surface navigation analysis of the performance of multiple lunar satellite constellations, Earth-based deep space network assets, and combinations thereof. Results show that kinematic and integrated solutions cannot be provided by the Earth-based deep space network stations. Also, the stationary surface navigation system needs to be operated either as a two-way navigation system or as a one-way navigation system with local terrain information, while the position solution is integrated over a short duration of time with navigation signals being provided by a lunar satellite constellation.

Multi-Terrain Earth Landing Systems Applicable for Manned Space Capsules

NASA Technical Reports Server (NTRS)

Fasanella, Edwin L.

2008-01-01

A key element of the President's Vision for Space Exploration is the development of a new space transportation system to replace Shuttle that will enable manned exploration of the moon, Mars, and beyond. NASA has tasked the Constellation Program with the development of this architecture, which includes the Ares launch vehicle and Orion manned spacecraft. The Orion spacecraft must carry six astronauts and its primary structure should be reusable, if practical. These requirements led the Constellation Program to consider a baseline land landing on return to earth. To assess the landing system options for Orion, a review of current operational parachute landing systems such as those used for the F-111 escape module and the Soyuz is performed. In particular, landing systems with airbags and retrorockets that would enable reusability of the Orion capsule are investigated. In addition, Apollo tests and analyses conducted in the 1960's for both water and land landings are reviewed. Finally, tests and dynamic finite element simulations to understand land landings for the Orion spacecraft are also presented.

Nanosat Intelligent Power System Development

NASA Technical Reports Server (NTRS)

Johnson, Michael A.; Beaman, Robert G.; Mica, Joseph A.; Truszkowski, Walter F.; Rilee, Michael L.; Simm, David E.

1999-01-01

NASA Goddard Space Flight Center is developing a class of satellites called nano-satellites. The technologies developed for these satellites will enable a class of constellation missions for the NASA Space Science Sun-Earth Connections theme and will be of great benefit to other NASA enterprises. A major challenge for these missions is meeting significant scientific- objectives with limited onboard and ground-based resources. Total spacecraft power is limited by the small satellite size. Additionally, it is highly desirable to minimize operational costs by limiting the ground support required to manage the constellation. This paper will describe how these challenges are met in the design of the nanosat power system. We will address the factors considered and tradeoffs made in deriving the nanosat power system architecture. We will discuss how incorporating onboard fault detection and correction capability yields a robust spacecraft power bus without the mass and volume penalties incurred from redundant systems and describe how power system efficiency is maximized throughout the mission duration.

REACH: Real-Time Data Awareness in Multi-Spacecraft Missions

NASA Technical Reports Server (NTRS)

Maks, Lori; Coleman, Jason; Hennessy, Joseph F. (Technical Monitor)

2002-01-01

NASA's Advanced Architectures and Automation Branch at the Goddard Space Flight Center (Code 588) saw the potential to reduce the cost of constellation missions by creating new user interfaces to the ground system health-and-safety data. The goal is to enable a small Flight Operations Team (FOT) to remain aware and responsive to the increased amount of ground system information in a multi-spacecraft environment. Rather than abandon the tried and true, these interfaces were developed to run alongside existing ground system software to provide additional support to the FOT. These new user interfaces have been combined in a tool called REACH. REACH-the Real-time Evaluation and Analysis of Consolidated Health-is a software product that uses advanced visualization techniques to make spacecraft anomalies easy to spot, no matter how many spacecraft are in the constellation. REACH reads numerous real-time streams of data from the ground system(s) and displays synthesized information to the FOT such that anomalies are easy to pick out and investigate.

Getting Students to Observe the Night Sky, Even When Your Sky is Cloudy Half the Time

NASA Astrophysics Data System (ADS)

Shipman, Harry L.

2010-01-01

Teachers of introductory astronomy classes often wish to get our students to look at the night sky However, most educational institutions in America are located in regions where cloudy nights are relatively common. This paper describes a low cost way to integrate observations into a course which lacks a dedicated astronomy lab. Students in two large. general science classes in fall 2008 and spring 2009 were asked to participate in one of two global star-counting projects. The fall project was coordinated by UCAR and asked for observations of the constellation Cygnus (http://www.windows.ucar.edu/citizen_science/starcount/results.html). The spring project was run by Project Globe and asked for observations of the constellation Orion. (http://www.globe.gov/GaN/ ). In both cases, students simply find the constellation, match the star pattern to charts that go to different limiting magnitudes, and report the data to the coordinating organization. A copy of the report is sent to the course instructor. The instructor can ask for additional information. Did it work? The success of this project was evaluated by analyzing the e-mail messages that students returned in response to the assignment. In both courses, a very large majority of the students actually did the exercise and submitted a report. Students reported that observing the sky in this way was satisfying to them., and sometimes the reports were quite enthusiastic. In spring 2009, some preparatory activies were conducted during class that were designed to sensitize students to the beauty of the sky. Analysis of student reports indicated that these preparatory activities were helpful, but not as helpful as the instructor would like. This research is part of the Teacher Professional Continuum project at the University of Delaware, which is supported by the National Science Foundation.

Water vapor variability and comparisons in the subtropical Pacific from The Observing System Research and Predictability Experiment-Pacific Asian Regional Campaign (T-PARC) Driftsonde, Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC), and reanalyses

NASA Astrophysics Data System (ADS)

Wang, Junhong; Zhang, Liangying; Lin, Po-Hsiung; Bradford, Mark; Cole, Harold; Fox, Jack; Hock, Terry; Lauritsen, Dean; Loehrer, Scot; Martin, Charlie; Vanandel, Joseph; Weng, Chun-Hsiung; Young, Kathryn

2010-11-01

During the THORPEX (The Observing System Research and Predictability Experiment) Pacific Asian Regional Campaign (T-PARC), from 1 August to 30 September 2008, ˜1900 high-quality, high vertical resolution soundings were collected over the Pacific Ocean. These include dropsondes deployed from four aircrafts and zero-pressure balloons in the stratosphere (NCAR's Driftsonde system). The water vapor probability distribution and spatial variability in the northern subtropical Pacific (14°-20°N, 140°E-155°W) are studied using Driftsonde and COSMIC (Constellation Observing System for Meteorology, Ionosphere, and Climate) data and four global reanalysis products. Driftsonde data analysis shows distinct differences of relative humidity (RH) distributions in the free troposphere between the Eastern and Western Pacific (EP and WP, defined as east and west of 180°, respectively), very dry with a single peak of ˜1% RH in the EP and bi-modal distributions in the WP with one peak near ice saturation and one varying with altitude. The frequent occurrences of extreme dry air are found in the driftsonde data with 59% and 19% of RHs less than or equal to 5% and at 1% at 500 hPa in the EP, respectively. RH with respect to ice in the free troposphere exhibits considerable longitudinal variations, very low (<20%) in the EP, but varying from 20% to 100% in the WP. Inter-comparisons of Driftsonde, COSMIC and reanalysis data show generally good agreement among the Driftsonde, COSMIC, ECMWF Reanalysis-Interim (ERA-Interim) and Japanese Reanalysis (JRA) below 200 hPa. The ERA-Interim and JRA are approved to be successful on describing RH frequency distributions and spatial variations in the region. The comparisons also reveal problems in Driftsonde, two National Center for Environmental Prediction (NCEP) reanalyses and COSMIC data. The moist layer at 200-100 hPa in the WP shown in the ERA-Interim, JRA and COSMIC is missing in Driftsonde data. Major problems are found in the RH means and variability over the study region for both NCEP reanalyses. Although the higher-moisture layer at 200-100 hPa in the WP in the COSMIC data agrees well with the ERA-Interim and JRA, it is primarily attributed to the first guess of the 1-Dimensional (1D) variational analysis used in the COSMIC retrieval rather than the refractivity measurements. The limited soundings (total 268) of Driftsonde data are capable of portraying RH probability distributions and longitudinal variability. This implies that Driftsonde system has the potential to become a valuable operational system for upper air observations over the ocean.

Constellation Program Press Conference

NASA Image and Video Library

2006-06-04

Jeff Hanley, Constellation Program Manager, speaks during a press conference outlining specific center responsibilities associated with the Constellation Program for robotic and human Moon and Mars exploration, Monday, June 5, 2006, at NASA Headquarters in Washington. Photo Credit (NASA/Bill Ingalls)

Life Support Technology Challenges for NASA's Constellation Program

NASA Technical Reports Server (NTRS)

Carrasquillo, Robyn; Bagdigian, Robert; Ewert, Michael

2007-01-01

The presentation is for the ECLSS session of the Constellation Technology Exchange Conference and is to describe what new technology challenges the Constellation mission presents for the ECLSS, in order to communicate these needs with industry.

Constellation Pharmacology: A new paradigm for drug discovery

PubMed Central

Schmidt, Eric W.; Olivera, Baldomero M.

2015-01-01

Constellation Pharmacology is a cell-based high-content phenotypic-screening platform that utilizes subtype-selective pharmacological agents to elucidate the cell-specific combinations (“constellations”) of key signaling proteins that define specific cell types. Heterogeneous populations of native cells, in which the different individual cell types have been identified and characterized, are the foundation for this screening platform. Constellation Pharmacology is useful for screening small molecules or for deconvoluting complex mixtures of biologically-active natural products. This platform has been used to purify natural products and discover their molecular mechanisms. In the on-going development of Constellation Pharmacology, there is a positive-feedback loop between the pharmacological characterization of cell types and screening for new drug candidates. As Constellation Pharmacology is used to discover compounds with novel targeting-selectivity profiles, those new compounds then further help to elucidate the constellations of specific cell types, thereby increasing the content of this high-content platform. PMID:25562646

Review of the Constellation Level II Safety, Reliability, and Quality Assurance (SR&QA) Requirements Documents during Participation in the Constellation Level II SR&QA Forum

NASA Technical Reports Server (NTRS)

Cameron, Kenneth D.; Gentz, Steven J.; Beil, Robert J.; Minute, Stephen A.; Currie, Nancy J.; Scott, Steven S.; Thomas, Walter B., III; Smiles, Michael D.; Schafer, Charles F.; Null, Cynthia H.;

Mt Pamola, the Electromagnetic Field, EMF, Thunderbird, Mothman and Environmental Monitoring Signals Via the Southern Constellation Phoenix As Detectable In Potato Cave, Acton, MA.

NASA Astrophysics Data System (ADS)

Pecora, Andrea S.; Pawa Matagamon, Sagamo

2004-03-01

Just below the peak of Mt Pamola in ME, at the juncture with the Knife Edge, downwardly arcing segments of Earths EMF, are manifested by a faint lotus-blossom-blue, neon-like glow at 3 pm some sunny afternoons. Similarly hued glows, and horizontal but variable-arced segmented trajectories, are somewhat periodically detectable under certain conditions in chambers at Acton, MA. These phenomena curiously have the filled-in profile that precisely matches the outline of the southern constellation Phoenix, which is never visible above the nighttime horizon locally. The stick-figure representation of the constellation Canis Major can also be detected in a chamber at Americas Stonehenge, two hours before it has arisen, at certain times. The sequence of phenomena visible at Acton correctly correlates with eclipses and other alignments of our solar system. Phoenix, a.k.a. Thunderbird and Mothman, is detectable elsewhere in MA.

Spire's 3U CubeSat GNSS-RO Constellation for Meteorological and Space Weather Applications

NASA Astrophysics Data System (ADS)

Nguyen, V.; Duly, T.; Ector, D.; Irisov, V.; Nogues-Correig, O.; Tan, L.; Yuasa, T.

2017-12-01

Spire Global, Inc., is a leading player in the nanosatellite sector and the first commercial company to provide GNSS radio occultation measurements to support meteorological and space weather forecasting. Each Spire satellite is equipped with a state-of-the-art, in-house designed software receiver, which is capable of open-loop tracking of occulted GNSS signals. By utilizing this receiver on a low-earth orbiting, 3U satellite constellation platform, Spire is able to provide high-quality profile measurements of the lower atmosphere as well as ionospheric total electron content and scintillation data at unprecedented low cost, coverage, and latency. In this talk, we provide an overview of the current capabilities of Spire's satellite constellation and radio occultation processing system. Recent results describing the state of the lower atmosphere and ionosphere will be presented and briefly discussed. Finally, we focus on Spire's future capabilities, and the potential impacts on both the meteorological and space weather scientific communities.

Fighting in a Contested Space Environment: Training Marines for Operations with Degraded or Denied Space-Enabled Capabilities

DTIC Science & Technology

2015-06-01

System UFG Ulchi Freedom Guardian UFO UHF Follow-On System UHF Ultra-High Frequency URE User Range Error VTC Video Teleconference WGS Wideband...in the UHF band; two legacy systems, Fleet Satellite Communication System (FLTSATCOM) and UHF Follow-on ( UFO ), and the new constellation being

Invited Talk: Photometry of Bright Variable Stars with the BRITE Constellation Nano-Satellites: Opportunities for Amateur Astronomers

NASA Astrophysics Data System (ADS)

Guinan, E. F.

2014-06-01

(Abstract only) The BRIght Target Explorer (BRITE) is a joint Austrian-Canadian-Polish Astronomy mission to carry out high precision photometry of bright (mv < 4 mag.) variable stars. BRITE consists of a "Constellation" of 20 × 20 × 20-cm nano-satellite cubes equipped with wide field (20 × 24 deg.) CCD cameras, control systems, solar panels, onboard computers, and so on. The first two (of up to six) satellites were successfully launched during February 2013. After post-launch commissioning, science operations commenced during October 2013. The primary goals are to carry out continuous multi-color (currently blue and red filters) high-precision millimag (mmag) photometry in particular locations in the sky. Typically these pointings will last for two to four months and secure simultaneous blue/red photometry of bright variable stars within the field. The first science pointing is centered on the Orion region. Since most bright stars are intrinsically luminous, hot O/B stars, giants, and supergiants will be the most common targets. However, some bright eclipsing binaries (such as Algol, b Lyr, e Aur) and a few chromospherically-active RS CVn stars (such as Capella) may be eventually be monitored. The BRITE-Constellation program of high precision, two color photometry of bright stars offers a great opportunity to study a wide range of stellar astrophysical problems. Bright stars offer convenient laboratories to study many current and important problems in stellar astrophysics. These include probing stellar interiors and pulsation in pulsating stars, tests of stellar evolution and structure for Cepheids and other luminous stars. To scientifically enhance the BRITE science returns, the BRITE investigators are very interested in securing contemporaneous ground-based spectroscopy and standardized photometry of target stars. The BRITE Ground Based Observations Team is coordinating ground-based observing efforts for BRITE targets. The team helps coordinate collaborations with amateur and professional astronomer. The ground-based coordinators are: Thomas Eversberg (thomas.eversberg@dlr.de) and, for spectroscopy, Contanze Zwintz (konstanze@ster.kuleuven.be). Detailed information about the BRITE Mission is provided at: www.brite-contellation.at.

Advances In Understanding Global Water Cycle With Advent of GPM Mission

NASA Technical Reports Server (NTRS)

Smith, Eric A.

2002-01-01

During the coming decade, the internationally organized Global Precipitation Measurement (GPM) Mission will take an important step in creating a global precipitation observing system from space based on an international fleet of satellites operated as a constellation. One perspective for understanding the nature of GPM is that it will be a hierarchical system of datastreams beginning with very high caliber combined dual frequency radar/passive microwave (PMW) rain-radiometer retrievals, to high caliber PMW rain-radiometer only retrievals, and then on to blends of the former datastreams with additional lower-caliber PMW-based and IR-based rain retrievals. Within the context of the now emerging global water & energy cycle (GWEC) programs of a number of research agencies throughout the world, GPM serves as a centerpiece space mission for improving our understanding of the Earth's water cycle from a global measurement perspective and on down to regional scales and below. One of the salient problems within our current understanding of the global water and energy cycle is determining whether a change in the rate of the water cycle is accompanying changes in climate, e.g., climate warming. As there are a number of ways in which to define a rate-change of the global water cycle, it is not entirely clear as to what constitutes such a determination. This paper first presents an overview of the GPM Mission and how its overriding scientific objectives for climate, weather, and hydrology flow from the anticipated improvements that are being planned for the constellation-based measuring system. Next, the paper shows how the GPM observations can be used within the framework of the oceanic and continental water budget equations to determine whether a given perturbation in precipitation is indicative of an actual rate change in the water cycle, consistent with required responses in water storage and/or water flux transport processes, or whether it is simply part of the natural variability of a fixed rate cycle.

Heat Exchanger/Humidifier Trade Study and Conceptual Design for the Constellation Space Suit Portable Life Support System Ventilation Subsystem

NASA Technical Reports Server (NTRS)

Paul, Heather L.; Sompayrac, Robert; Conger, Bruce; Chamberlain, Mateo

2009-01-01

As development of the Constellation Space Suit Element progresses, designing the most effective and efficient life support systems is critical. The baseline schematic analysis for the Portable Life Support System (PLSS) indicates that the ventilation loop will need some method of heat exchange and humidification prior to entering the helmet. A trade study was initiated to identify the challenges associated with conditioning the spacesuit breathing gas stream for temperature and water vapor control, to survey technological literature and resources on heat exchanger and humidifiers to provide solutions to the problems of conditioning the spacesuit breathing gas stream, and to propose potential candidate technologies to perform the heat exchanger and humidifier functions. This paper summarizes the results of this trade study and also describes the conceptual designs that NASA developed to address these issues.

Heat Exchanger/Humidifier Trade Study and Conceptual Design for the Constellation Space Suit Portable Life Support System Ventilation Subsystem

NASA Technical Reports Server (NTRS)

Paul, Heather L.; Conger, Bruce; Sompyrac, Robert; Chamberlain, Mateo

2008-01-01

As development of the Constellation Space Suit Element progresses, designing the most effective and efficient life support systems is critical. The baseline schematic analysis for the Portable Life Support System (PLSS) indicates that the ventilation loop will need some method of heat exchange and humidification prior to entering the helmet. A trade study was initiated to identify the challenges associated with conditioning the spacesuit breathing gas stream for temperature and water vapor control, to survey technological literature and resources on heat exchanger and humidifiers to provide solutions to the problems of conditioning the spacesuit breathing gas stream, and to propose potential candidate technologies to perform the heat exchanger and humidifier functions. This paper summarizes the results of this trade study and also describes the conceptual designs that NASA developed to address these issues.

Constellation Program Thermal and Environmental Control and Life Support System Status: 2009 - 2010

NASA Technical Reports Server (NTRS)

Williams, David E.; Carrasquillo, Robyn L.; Bagdigian, Robert M.

2009-01-01

The Constellation Program (CxP) consists of spacecrafts, launch vehicles, and support systems to execute the Exploration Architecture. The Program is currently divided into three distinct phases. The first phase is to develop a vehicle to provide limited cargo resupply capability and allow crew member rotation to the International Space Station (ISS). The second phase is to support the return of humans to the moon. The final phase is currently envisioned to allow the delivery of humans and cargo to Mars for an extended time. To implement this phased approach the CxP is currently working on the first vehicle and support systems to replace the Space Shuttle and allow continued access to space. This paper provides a summary of the CxP Thermal and Environmental Control and Life Support (ECLS) work that that has occurred across the different parts of the Program in support of these three phases over the past year.

Launching the Future... Constellation Program at KSC

NASA Technical Reports Server (NTRS)

Denson, Erik C.

2010-01-01

With the Constellation Program, NASA is entering a new age of space exploration that will take us back to the Moon, to Mars, and beyond, and NASA is developing the new technology and vehicles to take us there. At the forefront are the Orion spacecraft and the Ares I launch vehicle. As NASA's gateway to space, Kennedy Space Center (KSC) will process and launch the new vehicles. This will require new systems and extensive changes to existing infrastructure. KSC is designing a new mobile launcher, a new launch control system, and new ground support equipment; modifying the Vehicle Assembly Building, one of the launch pads, and other facilities; and launching the Ares I-X flight test. It is an exciting and challenging time to be an engineer at KSC.

An introduction to the global positioning system and some geological applications

NASA Technical Reports Server (NTRS)

Dixon, T. H.

1991-01-01

The fundamental principles of the global positioning system (GPS) are reviewed, with consideration given to geological and geophysical applications and related accuracy requirements. Recent improvements are emphasized which relate to areas such as equipment cost, limitations in the GPS satellite constellation, data analysis, uncertainties in satellite orbits and propagation delays, and problems in resolving carrier phase cycle ambiguities. Earthquake processes and near-fault crustal deformation monitoring have been facilitated by advances in GPS data acquisition and analysis. Horizontal positioning capability has been improved by new satellite constellation, better models, and global tracking networks. New classes of tectonic problems may now be studied through GPS, such as kinematic descriptions of crustal deformation and the measurement of relative plate motion at convergent boundaries. Continued improvements in the GPS are foreseen.

Results From the First 118 GHz Passive Microwave Observations Over Antarctica

NASA Astrophysics Data System (ADS)

McAllister, R.; Gallaher, D. W.; Gasiewski, A. J.; Periasamy, L.; Belter, R.; Hurowitz, M.; Hosack, W.; Sanders, B. T.

2017-12-01

Cooperation between the University of Colorado (Center for Environmental Technology, National Snow and Ice Data Center, and Colorado Space Grant Consortium) and the private corporation Orbital Micro Systems (OMS) has resulted in a highly miniturized passive microwave sensor. This sensor was successfully flown over Antarctica in onboard NASA's DC-8 in Operation Ice Bridge (OIB) in October / November of 2016. Data was collected from the "MiniRad" 8 channel miniaturized microwave sensor, which operated as both a sounder and an imager. The non-calibrated observation included both high and low altitude observations over clouds, sea, ice, ice sheets, and mountains as well as terrain around Tierra del Fuego. Sample results and their significance will be discussed. The instrument is in a form factor suitable for deployment in cubesats and will be launched into orbit next year. Commercial deployments by OMS in a constellation configuration will shortly follow.

The Interplanetary Meteoroid Environment for eXploration

NASA Astrophysics Data System (ADS)

Soja, R.; Sommer, M.; Srama, R.; Strub, P.; Grün, E.; Rodmann, J.; Vaubaillon, J.; Hornig, A.; Bausch, L.

2014-07-01

The Interplanetary Meteoroid Environment for eXploration (IMEX) project, funded by the European Space Agency (ESA), aims to characterize dust trails and streams produced by comets in the inner solar system. The goal is to predict meteor showers at any position or time in the solar system, such as at specific spacecraft or planets. This model will allow for the assessment of the dust impact hazard to spacecraft, which is important because hypervelocity impacts of micrometeoroids can damage or destroy spacecraft or their subsystems through physical damage or electromagnetic effects. Such considerations are particularly important in the context of human exploration of the solar system. Additionally, such a model will allow for scientific study of specific trails and their connections to observed dust phenomena, such as cometary trails and new meteor showers at Earth. We have recently expanded the model to include explicit integrations of large numbers of particles from each comet, utilizing the Constellation platform to perform the calculations. This is a distributed computing system, where currently 10,000 users are donating their idle computing time at home and thus generating a virtual supercomputer of 40,000 host PCs connected via the Internet (aerospaceresearch.net). This form of citizen science provides the required computing performance for simulating millions of particles ejected by each of the ˜400 comets, while developing the relationship between scientists and the general public. The result will be a unique set of saved orbital information for a large number of cometary streams, allowing efficient computation of their locations at any point in space and time. Here we will present the results from several test streams and discuss the progress towards obtaining the full set of integrated particles for each of the selected ˜400 short-period comets. individual Constellation users for their computing time.

Swarm: ESA's Magnetic Field Mission

NASA Astrophysics Data System (ADS)

Plank, G.; Floberghagen, R.; Menard, Y.; Haagmans, R.

2012-12-01

Swarm is the fifth Earth Explorer mission in ESA's Living Planet Programme, and is scheduled for launch in fall 2012. The objective of the Swarm mission is to provide the best-ever survey of the geomagnetic field and its temporal evolution using a constellation of three identical satellites. The mission shall deliver data that allow access to new insights into the Earth system by improved scientific understanding of the Earth's interior and near-Earth electromagnetic environment. After launch and triple satellite release at an initial altitude of about 490 km, a pair of the satellites will fly side-by-side with slowly decaying altitude, while the third satellite will be lifted to 530 km to complete the Swarm constellation. High-precision and high-resolution measurements of the strength, direction and variation of the magnetic field, complemented by precise navigation, accelerometer and electric field measurements, will provide the observations required to separate and model various sources of the geomagnetic field and near-Earth current systems. The mission science goals are to provide a unique view into Earth's core dynamics, mantle conductivity, crustal magnetisation, ionospheric and magnetospheric current systems and upper atmosphere dynamics - ranging from understanding the geodynamo to contributing to space weather. The scientific objectives and results from recent scientific studies will be presented. In addition the current status of the project, which is presently in the final stage of the development phase, will be addressed. A consortium of European scientific institutes is developing a distributed processing system to produce geophysical (Level 2) data products for the Swarm user community. The setup of the Swarm ground segment and the contents of the data products will be addressed. In case the Swarm satellites are already in orbit, a summary of the on-going mission operations activities will be given.

Near-Real-Time Detection and Monitoring of Intense Pyroconvection from Geostationary Satellites

NASA Astrophysics Data System (ADS)

Peterson, D. A.; Fromm, M. D.; Hyer, E. J.; Surratt, M. L.; Solbrig, J. E.; Campbell, J. R.

2016-12-01

Intense fire-triggered thunderstorms, known as pyrocumulonimbus (or pyroCb), can alter fire behavior, influence smoke plume trajectories, and hinder fire suppression efforts. PyroCb are also known for injecting a significant quantity of aerosol mass into the upper-troposphere and lower-stratosphere (UTLS). Near-real-time (NRT) detection and monitoring of pyroCb is highly desirable for a variety of forecasting and research applications. The Naval Research Laboratory (NRL) recently developed the first automated NRT pyroCb detection algorithm for geostationary satellite sensors. The algorithm uses multispectral infrared observations to isolate deep convective clouds with the distinct microphysical signal of pyroCb. Application of this algorithm to 88 intense wildfires observed during the 2013 fire season in western North America resulted in detection of individual intense events, pyroCb embedded within traditional convection, and multiple, short-lived pulses of activity. Comparisons with a community inventory indicate that this algorithm captures the majority of pyroCb. The primary limitation of the current system is that pyroCb anvils can be small relative to satellite pixel size, especially in in regions with large viewing angles. The algorithm is also sensitive to some false positives from traditional convection that either ingests smoke or exhibits extreme updraft velocities. This algorithm has been automated using the GeoIPS processing system developed at NRL, which produces a variety of imagery products and statistical output for rapid analysis of potential pyroCb events. NRT application of this algorithm has been extended to the majority of regions worldwide known to have a high frequency of pyroCb occurrence. This involves a constellation comprised of GOES-East, GOES-West, and Himawari-8. Imagery is posted immediately to an NRL-maintained web page. Alerts are generated by the system and disseminated via email. This detection system also has potential to serve as a data source for other NRT environmental monitoring systems. While the current geostationary constellation has several important limitations, the next-generation of geostationary sensors will offer significant advantages for achieving the goal of global NRT pyroCb detection.

NASA Range Safety Annual Report 2007

NASA Technical Reports Server (NTRS)

Dumont, Alan G.

2007-01-01

As always, Range Safety has been involved in a number of exciting and challenging activities and events. Throughout the year, we have strived to meet our goal of protecting the public, the workforce, and property during range operations. During the past year, Range Safety was involved in the development, implementation, and support of range safety policy. Range Safety training curriculum development was completed this year and several courses were presented. Tailoring exercises concerning the Constellation Program were undertaken with representatives from the Constellation Program, the 45th Space Wing, and the Launch Constellation Range Safety Panel. Range Safety actively supported the Range Commanders Council and it subgroups and remained involved in updating policy related to flight safety systems and flight safety analysis. In addition, Range Safety supported the Space Shuttle Range Safety Panel and addressed policy concerning unmanned aircraft systems. Launch operations at Kennedy Space Center, the Eastern and Western ranges, Dryden Flight Research Center, and Wallops Flight Facility were addressed. Range Safety was also involved in the evaluation of a number of research and development efforts, including the space-based range (formerly STARS), the autonomous flight safety system, the enhanced flight termination system, and the joint advanced range safety system. Flight safety system challenges were evaluated. Range Safety's role in the Space Florida Customer Assistance Service Program for the Eastern Range was covered along with our support for the Space Florida Educational Balloon Release Program. We hope you have found the web-based format both accessible and easy to use. Anyone having questions or wishing to have an article included in the 2008 Range Safety Annual Report should contact Alan Dumont, the NASA Range Safety Program Manager located at the Kennedy Space Center, or Michael Dook at NASA Headquarters.

The impact of GPS receiver modifications and ionospheric activity on Swarm baseline determination

NASA Astrophysics Data System (ADS)

Mao, X.; Visser, P. N. A. M.; van den IJssel, J.

2018-05-01

The European Space Agency (ESA) Swarm mission is a satellite constellation launched on 22 November 2013 aiming at observing the Earth geomagnetic field and its temporal variations. The three identical satellites are equipped with high-precision dual-frequency Global Positioning System (GPS) receivers, which make the constellation an ideal test bed for baseline determination. From October 2014 to August 2016, a number of GPS receiver modifications and a new GPS Receiver Independent Exchange Format (RINEX) converter were implemented. Moreover, the on-board GPS receiver performance has been influenced by the ionospheric scintillations. The impact of these factors is assessed for baseline determination of the pendulum formation flying Swarm-A and -C satellites. In total 30 months of data - from 15 July 2014 to the end of 2016 - is analyzed. The assessment includes analysis of observation residuals, success rate of GPS carrier phase ambiguity fixing, a consistency check between the so-called kinematic and reduced-dynamic baseline solution, and validations of orbits by comparing with Satellite Laser Ranging (SLR) observations. External baseline solutions from The German Space Operations Center (GSOC) and Astronomisches Institut - Universität Bern (AIUB) are also included in the comparison. Results indicate that the GPS receiver modifications and RINEX converter changes are effective to improve the baseline determination. This research eventually shows a consistency level of 9.3/4.9/3.0 mm between kinematic and reduced-dynamic baselines in the radial/along-track/cross-track directions. On average 98.3% of the epochs have kinematic solutions. Consistency between TU Delft and external reduced-dynamic baseline solutions is at a level of 1 mm level in all directions.

Status and Perspective of the IGS Multi-GNSS Experiment (MGEX)

NASA Astrophysics Data System (ADS)

Steigenberger, Peter; Montenbruck, Oliver; Weber, Robert; Hugentobler, Urs

2013-04-01

Following three decades, during which the Global Positioning System GPS has evolved from a military navigation system into an indispensable tool for geodetic research and global monitoring of the Earth, the world of satellite navigation has experienced dramatic changes over the past years. With GLONASS, a second global navigation system has achieved a fully operational status, GPS is introducing modernized civil and encrypted navigation signals, and a variety of new navigation constellations are being built-up in Asia and Europe. These include BeiDou, which has recently opened a regional navigation service in the Asia-Pacific region, Galileo, which now has four satellites in orbit, as well as QZSS, which offers a unique set of signals and service features. In recognition of a rapidly changing GNSS landscape, the International GNSS Service (IGS) has initiated the Multi-GNSS Experiment (MGEX - http://igs.org/mgex) as a platform for early familiarization with emerging navigation systems and to pave the way for a full-featured use thereof in a future multi-GNSS service. As a first step, MGEX has promoted the build-up of a new global network of GNSS monitoring stations, each tracking at least one new constellation (Galileo, BeiDou, or QZSS) on top of GPS, GLONASS and SBAS. By the end of 2012, approximately 50 stations contribute offline and/or real-time data to the MGEX network. To facilitate introduction of new standards (specifically RINEX3 observation and navigation data formats), distinct data archives are used even for those MGEX stations jointly contributing to the legacy IGS. Building-up on the new multi-GNSS network, the generation of associated orbit and clock products has started in the second quarter of 2012. At this stage, only Galileo and QZSS products are offered by selected MGEX Analysis Centers, but the addition of BeiDou is expected in 2013 as the MGEX network expands and new Analysis Centers join the data processing effort. Despite remarkable progress in the first year of the MGEX project, numerous challenges have still to be met before the new constellations can contribute to high-grade navigation and geodetic services. So far, only an immature knowledge of the new navigation satellites and the transmitted signals is available. Much work is left to fully characterize the multitude of inter-signal, inter-frequency and inter-system biases, as well as antenna phase patterns in both the space and user segment. Likewise, proper knowledge of spacecraft attitude control and radiation pressure models appears indispensable for a proper generation of highly-accurate orbit and clock products. Only then will users be able to fully benefit from the high potential of robust, wide-band, and high navigation signals as well as new generations of highly stable clocks offered by the new constellations. Within the presentation, the MGEX project will be introduced and the latest achievements in the network build-up, the product generation and related activities will be presented. Current challenges and necessary steps towards a full-features multi-GNSS service of the IGS will be identified.

Constellation Program Update

NASA Image and Video Library

2006-06-04

Jeff Hanley, Constellation Program Manager, announces to NASA employees and members of the media the responsibilities of the NASA centers associated with the Constellation Program for robotic and human Moon and Mars exploration on Wednesday, June 5, 2006, at NASA Headquarters in Washington. Photo Credit: (NASA/Bill Ingalls)

Constellation Program Update

NASA Image and Video Library

2006-06-04

Jeff Hanley, Constellation Program Manager, right, listens to a question during a NASA Update outlining responsibilities of the NASA centers associated with the Constellation Program for robotic and human Moon and Mars exploration on Wednesday, June 5, 2006, at NASA Headquarters in Washington. Photo Credit: (NASA/Bill Ingalls)

Navigation Performance of Global Navigation Satellite Systems in the Space Service Volume

NASA Technical Reports Server (NTRS)

Force, Dale A.

2013-01-01

This paper extends the results I reported at this year's ION International Technical Meeting on multi-constellation GNSS coverage by showing how the use of multi-constellation GNSS improves Geometric Dilution of Precision (GDOP). Originally developed to provide position, navigation, and timing for terrestrial users, GPS has found increasing use for in space for precision orbit determination, precise time synchronization, real-time spacecraft navigation, and three-axis attitude control of Earth orbiting satellites. With additional Global Navigation Satellite Systems (GNSS) coming into service (GLONASS, Galileo, and Beidou) and the development of Satellite Based Augmentation Services, it is possible to obtain improved precision by using evolving multi-constellation receiver. The Space Service Volume formally defined as the volume of space between three thousand kilometers altitude and geosynchronous altitude ((is) approximately 36,500 km), with the volume below three thousand kilometers defined as the Terrestrial Service Volume (TSV). The USA has established signal requirements for the Space Service Volume (SSV) as part of the GPS Capability Development Documentation (CDD). Diplomatic efforts are underway to extend Space service Volume commitments to the other Position, Navigation, and Timing (PNT) service providers in an effort to assure that all space users will benefit from the enhanced capabilities of interoperating GNSS services in the space domain.

Constellation X-Ray Mission and Support

NASA Technical Reports Server (NTRS)

Tananbaum, H.; Grady, Jean (Technical Monitor)

2002-01-01

This report is a supplement to the Third Annual Report summarizing work performed by the Smithsonian Astrophysical Observatory (SAO) for NASA Goddard Space Flight Center (GSFC) under Cooperative Agreement NCC5-3681. The Agreement is entitled 'Constellation X-ray Mission Study and Support.' This supplementary report covers the period from October 1, 2001 through January 10, 2002. The report has been prepared and submitted to ensure that the Constellation-X Project Office at GSFC has current performance information needed to evaluate a proposed modified budget for FY02. That proposed budget is being submitted separately. SAO continues to perform work under the overall direction of Dr. Harvey Tananbaum, the SAO Principal Investigator for the program. Mr. Robert Rasche is the SAO Program Manager and is responsible for day-to-day program management at SAO and coordination with GSFC. The report summarizes the main areas of SAO activity. Most of the work has been done jointly with personnel from GSFC and Marshall Space Flight Center (MSFC). We describe SAO participation in these efforts. Under the Agreement, SAO performed work in seven major areas of activity. These areas related to: (1) Constellation X-ray Mission Facility Definition Team and Study Management; (2) Science Support; (3) Spectroscopy X-ray Telescope (SXT); (4) Systems Engineering; (5) Travel in Support of the Work Effort; and (6) In-house Management and Coordination.

Study of tracking and data acquisition system for the 1990's. Volume 4: TDAS space segment architecture

NASA Technical Reports Server (NTRS)

Orr, R. S.

1984-01-01

Tracking and data acquisition system (TDAS) requirements, TDAS architectural goals, enhanced TDAS subsystems, constellation and networking options, TDAS spacecraft options, crosslink implementation, baseline TDAS space segment architecture, and treat model development/security analysis are addressed.

Global coverage Mobile Satellite Systems: System availability versus channel propagation impairments

NASA Technical Reports Server (NTRS)

Sforza, M.; Buonomo, S.; Poiaresbaptista, J. P. V.

1993-01-01

Mobile Satellite Systems (MSS) in Highly Elliptical (HEO) and circular Earth orbits at Medium (MEO) and Low (LEO) altitudes have been intensively studied in the last few years as an effective means of providing global communication services. Such global coverage MSS networks are also expected to mitigate typical channel impairments usually encountered in geostationary Land Mobile Satellite (LMS) systems. In the design stages of these satellite networks, information regarding the mobile propagation channel is needed to assess the overall link availability versus elevation angle and environmental scenarios. For multisatellite LMS configurations, the mobile user on the Earth surface sees, at any given time, more than one satellite of the constellation. In our paper, it is shown that, under certain working assumptions regarding the statistics of the propagation channel, an improvement of the link availability may be achieved through the use of a multisatellite constellation. The analyses have been carried out using the European Space Agency (ESA) LMS propagation data base which presently covers a wide range of elevation angles and environmental scenarios.

GPM Avionics Module Heat Pipes Design and Performance Test Results

NASA Technical Reports Server (NTRS)

Ottenstein, Laura; DeChristopher, Mike

2012-01-01

GPM is a satellite constellation to study precipitation formed from a partnership between NASA and the Japanese Aerospace Exploration Agency (JAXA). The GPM Core Observatory, being developed and tested at GSFC, serves as a reference standard to unify precipitation measurements from the GPM satellite constellation. The Core Observatory carries an advanced radar/radiometer system to measure precipitation from space. The scientific data gained from GPM will benefit both NASA and JAXA by advancing our understanding of Earth's water and energy cycle, improving forecasts of extreme weather events, and extending our current capabilities in using accurate and timely precipitation information to benefit society.

Exploration Update

NASA Technical Reports Server (NTRS)

2006-01-01

Delores Beasley, NASA Public Affairs, introduces the panel who consist of: Scott "Doc" Horowitz, Associate Administrator of Exploration Systems from NASA Headquarters; Jeff Henley, Constellation Program Manager from NASA Johnson Space Flight Center; and Steve Cook, Manager Exploration Launch Office at NASA Marshall Space Flight Center. Scott Horowitz presents a short video entitled, "Ares Launching the Future". He further explains how NASA personnel came up with the name of Ares and where the name Ares was derived. Jeff Henley, updates the Constellation program and Steve Cook presents two slide presentations detailing the Ares l crew launch vehicle and Ares 5 cargo launch vehicle. A short question and answer period from the news media follows.

Learning the Constellations: From Junior High to Undergraduate Descriptive Astronomy Class

NASA Astrophysics Data System (ADS)

Stephens, Denise C.; Hintz, Eric G.; Hintz, Maureen; Lawler, Jeannette; Jones, Michael; Bench, Nathan

2015-01-01

As part of two separate studies we have examined the ability of students to learn and remember a group of constellations, bright stars, and deep sky objects. For a group of junior high students we tested their knowledge of only the constellations by giving them a 'constellation quiz' without any instruction. We then provided the students with a lab session, and retested. We also tested a large number of undergraduate students in our descriptive astronomy classes, but in this case there were the same 30 constellations, 17 bright stars, and 3 deep sky objects. The undergraduate students were tested in a number of ways: 1) pre-testing without instruction, 2) self-reporting of knowledge, 3) normal constellation quizzes as part of the class, and 4) retesting students from previous semesters. This provided us with a set of baseline measurements, allowed us to track the learning curve, and test retention of the material. We will present our early analysis of the data.

Global precipitation measurement (GPM) preliminary design

NASA Astrophysics Data System (ADS)

Neeck, Steven P.; Kakar, Ramesh K.; Azarbarzin, Ardeshir A.; Hou, Arthur Y.

2008-10-01

The overarching Earth science mission objective of the Global Precipitation Measurement (GPM) mission is to develop a scientific understanding of the Earth system and its response to natural and human-induced changes. This will enable improved prediction of climate, weather, and natural hazards for present and future generations. The specific scientific objectives of GPM are advancing: Precipitation Measurement through combined use of active and passive remote-sensing techniques, Water/Energy Cycle Variability through improved knowledge of the global water/energy cycle and fresh water availability, Climate Prediction through better understanding of surface water fluxes, soil moisture storage, cloud/precipitation microphysics and latent heat release, Weather Prediction through improved numerical weather prediction (NWP) skills from more accurate and frequent measurements of instantaneous rain rates with better error characterizations and improved assimilation methods, Hydrometeorological Prediction through better temporal sampling and spatial coverage of highresolution precipitation measurements and innovative hydro-meteorological modeling. GPM is a joint initiative with the Japan Aerospace Exploration Agency (JAXA) and other international partners and is the backbone of the Committee on Earth Observation Satellites (CEOS) Precipitation Constellation. It will unify and improve global precipitation measurements from a constellation of dedicated and operational active/passive microwave sensors. GPM is completing the Preliminary Design Phase and is advancing towards launch in 2013 and 2014.

VEGA, a small launch vehicle

NASA Astrophysics Data System (ADS)

Duret, François; Fabrizi, Antonio

1999-09-01

Several studies have been performed in Europe aiming to promote the full development of a small launch vehicle to put into orbit one ton class spacecrafts. But during the last ten years, the european workforce was mainly oriented towards the qualification of the heavy class ARIANE 5 launch vehicle.Then, due also to lack of visibility on this reduced segment of market, when comparing with the geosatcom market, no proposal was sufficiently attractive to get from the potentially interrested authorities a clear go-ahead, i.e. a financial committment. The situation is now rapidly evolving. Several european states, among them ITALY and FRANCE, are now convinced of the necessity of the availability of such a transportation system, an important argument to promote small missions, using small satellites. Application market will be mainly scientific experiments and earth observation; some telecommunications applications may be also envisaged such as placement of little LEO constellation satellites, or replacement after failure of big LEO constellation satellites. FIAT AVIO and AEROSPATIALE have proposed to their national agencies the development of such a small launch vehicle, named VEGA. The paper presents the story of the industrial proposal, and the present status of the project: Mission spectrum, technical definition, launch service and performance, target development plan and target recurring costs, as well as the industrial organisation for development, procurement, marketing and operations.

End-to-End Trade-space Analysis for Designing Constellation Missions

NASA Astrophysics Data System (ADS)

LeMoigne, J.; Dabney, P.; Foreman, V.; Grogan, P.; Hache, S.; Holland, M. P.; Hughes, S. P.; Nag, S.; Siddiqi, A.

2017-12-01

Multipoint measurement missions can provide a significant advancement in science return and this science interest coupled with many recent technological advances are driving a growing trend in exploring distributed architectures for future NASA missions. Distributed Spacecraft Missions (DSMs) leverage multiple spacecraft to achieve one or more common goals. In particular, a constellation is the most general form of DSM with two or more spacecraft placed into specific orbit(s) for the purpose of serving a common objective (e.g., CYGNSS). Because a DSM architectural trade-space includes both monolithic and distributed design variables, DSM optimization is a large and complex problem with multiple conflicting objectives. Over the last two years, our team has been developing a Trade-space Analysis Tool for Constellations (TAT-C), implemented in common programming languages for pre-Phase A constellation mission analysis. By evaluating alternative mission architectures, TAT-C seeks to minimize cost and maximize performance for pre-defined science goals. This presentation will describe the overall architecture of TAT-C including: a User Interface (UI) at several levels of details and user expertise; Trade-space Search Requests that are created from the Science requirements gathered by the UI and validated by a Knowledge Base; a Knowledge Base to compare the current requests to prior mission concepts to potentially prune the trade-space; a Trade-space Search Iterator which, with inputs from the Knowledge Base, and, in collaboration with the Orbit & Coverage, Reduction & Metrics, and Cost& Risk modules, generates multiple potential architectures and their associated characteristics. TAT-C leverages the use of the Goddard Mission Analysis Tool (GMAT) to compute coverage and ancillary data, modeling orbits to balance accuracy and performance. The current version includes uniform and non-uniform Walker constellations as well as Ad-Hoc and precessing constellations, and its cost model represents an aggregate model consisting of Cost Estimating Relationships (CERs) from widely accepted models. The current GUI automatically generates graphics representing metrics such as average revisit time or coverage as a function of cost. The end-to-end system will be demonstrated as part of the presentation.

End-to-End Trade-Space Analysis for Designing Constellation

NASA Technical Reports Server (NTRS)

Le Moigne, Jacqueline; Dabney, Philip; Foreman, Veronica; Grogan, Paul T.; Hache, Sigfried; Holland, Matthew; Hughes, Steven; Nag, Sreeja; Siddiqi, Afreen

2017-01-01

Multipoint measurement missions can provide a significant advancement in science return and this science interest coupled with as many recent technological advances are driving a growing trend in exploring distributed architectures for future NASA missions. Distributed Spacecraft Missions (DSMs) leverage multiple spacecraft to achieve one or more common goals. In particular, a constellation is the most general form of DSM with two or more spacecraft placed into specific orbit(s) for the purpose of serving a common objective (e.g., CYGNSS). Because a DSM architectural trade-space includes both monolithic and distributed design variables, DSM optimization is a large and complex problem with multiple conflicting objectives. Over the last two years, our team has been developing a Trade-space Analysis Tool for Constellations (TAT-C), implemented in common programming languages for pre-Phase A constellation mission analysis. By evaluating alternative mission architectures, TAT-C seeks to minimize cost and maximize performance for pre-defined science goals. This presentation will describe the overall architecture of TAT-C including: a User Interface (UI) at several levels of details and user expertise; Trade-space Search Requests that are created from the Science requirements gathered by the UI and validated by a Knowledge Base; a Knowledge Base to compare the current requests to prior mission concepts to potentially prune the trade-space; a Trade-space Search Iterator which, with inputs from the Knowledge Base, and, in collaboration with the Orbit & Coverage, Reduction & Metrics, and Cost& Risk modules, generates multiple potential architectures and their associated characteristics. TAT-C leverages the use of the Goddard Mission Analysis Tool (GMAT) to compute coverage and ancillary data, modeling orbits to balance accuracy and performance. The current version includes uniform and non-uniform Walker constellations as well as Ad-Hoc and precessing constellations, and its cost model represents an aggregate model consisting of Cost Estimating Relationships (CERs) from widely accepted models. The current GUI automatically generates graphics representing metrics such as average revisit time or coverage as a function of cost. The end-to-end system will be demonstrated as part of the presentation.

The Origin of Our Constellations.

ERIC Educational Resources Information Center

Ridpath, Ian

1990-01-01

Reviewed is the history of the naming of the constellations which appear in the sky. The roles of many ancient peoples through the astronomers of the eighteenth century up to the adoption of the official list of 88 constellations produced in 1922 by the International Astronomical Union are discussed. (CW)

Development of a Nonlinear Probability of Collision Tool for the Earth Observing System

NASA Technical Reports Server (NTRS)

McKinley, David P.

2006-01-01

The Earth Observing System (EOS) spacecraft Terra, Aqua, and Aura fly in constellation with several other spacecraft in 705-kilometer mean altitude sun-synchronous orbits. All three spacecraft are operated by the Earth Science Mission Operations (ESMO) Project at Goddard Space Flight Center (GSFC). In 2004, the ESMO project began assessing the probability of collision of the EOS spacecraft with other space objects. In addition to conjunctions with high relative velocities, the collision assessment method for the EOS spacecraft must address conjunctions with low relative velocities during potential collisions between constellation members. Probability of Collision algorithms that are based on assumptions of high relative velocities and linear relative trajectories are not suitable for these situations; therefore an algorithm for handling the nonlinear relative trajectories was developed. This paper describes this algorithm and presents results from its validation for operational use. The probability of collision is typically calculated by integrating a Gaussian probability distribution over the volume swept out by a sphere representing the size of the space objects involved in the conjunction. This sphere is defined as the Hard Body Radius. With the assumption of linear relative trajectories, this volume is a cylinder, which translates into simple limits of integration for the probability calculation. For the case of nonlinear relative trajectories, the volume becomes a complex geometry. However, with an appropriate choice of coordinate systems, the new algorithm breaks down the complex geometry into a series of simple cylinders that have simple limits of integration. This nonlinear algorithm will be discussed in detail in the paper. The nonlinear Probability of Collision algorithm was first verified by showing that, when used in high relative velocity cases, it yields similar answers to existing high relative velocity linear relative trajectory algorithms. The comparison with the existing high velocity/linear theory will also be used to determine at what relative velocity the analysis should use the new nonlinear theory in place of the existing linear theory. The nonlinear algorithm was also compared to a known exact solution for the probability of collision between two objects when the relative motion is strictly circular and the error covariance is spherically symmetric. Figure I shows preliminary results from this comparison by plotting the probabilities calculated from the new algorithm and those from the exact solution versus the Hard Body Radius to Covariance ratio. These results show about 5% error when the Hard Body Radius is equal to one half the spherical covariance magnitude. The algorithm was then combined with a high fidelity orbit state and error covariance propagator into a useful tool for analyzing low relative velocity nonlinear relative trajectories. The high fidelity propagator is capable of using atmospheric drag, central body gravitational, solar radiation, and third body forces to provide accurate prediction of the relative trajectories and covariance evolution. The covariance propagator also includes a process noise model to ensure realistic evolutions of the error covariance. This paper will describe the integration of the nonlinear probability algorithm and the propagators into a useful collision assessment tool. Finally, a hypothetical case study involving a low relative velocity conjunction between members of the Earth Observation System constellation will be presented.

On Several Fundamental Problems of Optimization, Estimation, and Scheduling in Wireless Communications

NASA Astrophysics Data System (ADS)

Gao, Qian

For both the conventional radio frequency and the comparably recent optical wireless communication systems, extensive effort from the academia had been made in improving the network spectrum efficiency and/or reducing the error rate. To achieve these goals, many fundamental challenges such as power efficient constellation design, nonlinear distortion mitigation, channel training design, network scheduling and etc. need to be properly addressed. In this dissertation, novel schemes are proposed accordingly to deal with specific problems falling in category of these challenges. Rigorous proofs and analyses are provided for each of our work to make a fair comparison with the corresponding peer works to clearly demonstrate the advantages. The first part of this dissertation considers a multi-carrier optical wireless system employing intensity modulation (IM) and direct detection (DD). A block-wise constellation design is presented, which treats the DC-bias that conventionally used solely for biasing purpose as an information basis. Our scheme, we term it MSM-JDCM, takes advantage of the compactness of sphere packing in a higher dimensional space, and in turn power efficient constellations are obtained by solving an advanced convex optimization problem. Besides the significant power gains, the MSM-JDCM has many other merits such as being capable of mitigating nonlinear distortion by including a peak-to-power ratio (PAPR) constraint, minimizing inter-symbol-interference (ISI) caused by frequency-selective fading with a novel precoder designed and embedded, and further reducing the bit-error-rate (BER) by combining with an optimized labeling scheme. The second part addresses several optimization problems in a multi-color visible light communication system, including power efficient constellation design, joint pre-equalizer and constellation design, and modeling of different structured channels with cross-talks. Our novel constellation design scheme, termed CSK-Advanced, is compared with the conventional decoupled system with the same spectrum efficiency to demonstrate the power efficiency. Crucial lighting requirements are included as optimization constraints. To control non-linear distortion, the optical peak-to-average-power ratio (PAPR) of LEDs can be individually constrained. With a SVD-based pre-equalizer designed and employed, our scheme can achieve lower BER than counterparts applying zero-forcing (ZF) or linear minimum-mean-squared-error (LMMSE) based post-equalizers. Besides, a binary switching algorithm (BSA) is applied to improve BER performance. The third part looks into a problem of two-phase channel estimation in a relayed wireless network. The channel estimates in every phase are obtained by the linear minimum mean squared error (LMMSE) method. Inaccurate estimate of the relay to destination (RtD) channel in phase 1 could affect estimate of the source to relay (StR) channel in phase 2, which is made erroneous. We first derive a close-form expression for the averaged Bayesian mean-square estimation error (ABMSE) for both phase estimates in terms of the length of source and relay training slots, based on which an iterative searching algorithm is then proposed that optimally allocates training slots to the two phases such that estimation errors are balanced. Analysis shows how the ABMSE of the StD channel estimation varies with the lengths of relay training and source training slots, the relay amplification gain, and the channel prior information respectively. The last part deals with a transmission scheduling problem in a uplink multiple-input-multiple-output (MIMO) wireless network. Code division multiple access (CDMA) is assumed as a multiple access scheme and pseudo-random codes are employed for different users. We consider a heavy traffic scenario, in which each user always has packets to transmit in the scheduled time slots. If the relay is scheduled for transmission together with users, then it operates in a full-duplex mode, where the packets previously collected from users are transmitted to the destination while new packets are being collected from users. A novel expression of throughput is first derived and then used to develop a scheduling algorithm to maximize the throughput. Our full-duplex scheduling is compared with a half-duplex scheduling, random access, and time division multiple access (TDMA), and simulation results illustrate its superiority. Throughput gains due to employment of both MIMO and CDMA are observed.

KSC-2009-5541

NASA Image and Video Library

2009-10-20

CAPE CANAVERAL, Fla. - Inside the Vehicle Assembly Building at NASA's Kennedy Space Center in Florida, the 327-foot-tall Ares I-X rocket stands on its mobile launcher platform. The transfer of the pad from the Space Shuttle Program to the Constellation Program took place May 31. Modifications made to the pad include the removal of shuttle unique subsystems, such as the orbiter access arm and a section of the gaseous oxygen vent arm, along with the installation of three 600-foot lightning towers, access platforms, environmental control systems and a vehicle stabilization system. Part of the Constellation Program, the Ares I-X is the test vehicle for the Ares I. The Ares I-X flight test is targeted for Oct. 27. For information on the Ares I-X vehicle and flight test, visit http://www.nasa.gov/aresIX. Photo credit: NASA/Kim Shiflett

Analysis of Space Shuttle Ground Support System Fault Detection, Isolation, and Recovery Processes and Resources

NASA Technical Reports Server (NTRS)

Gross, Anthony R.; Gerald-Yamasaki, Michael; Trent, Robert P.

2009-01-01

As part of the FDIR (Fault Detection, Isolation, and Recovery) Project for the Constellation Program, a task was designed within the context of the Constellation Program FDIR project called the Legacy Benchmarking Task to document as accurately as possible the FDIR processes and resources that were used by the Space Shuttle ground support equipment (GSE) during the Shuttle flight program. These results served as a comparison with results obtained from the new FDIR capability. The task team assessed Shuttle and EELV (Evolved Expendable Launch Vehicle) historical data for GSE-related launch delays to identify expected benefits and impact. This analysis included a study of complex fault isolation situations that required a lengthy troubleshooting process. Specifically, four elements of that system were considered: LH2 (liquid hydrogen), LO2 (liquid oxygen), hydraulic test, and ground special power.

An improved scheme for Flip-OFDM based on Hartley transform in short-range IM/DD systems.

PubMed

Zhou, Ji; Qiao, Yaojun; Cai, Zhuo; Ji, Yuefeng

2014-08-25

In this paper, an improved Flip-OFDM scheme is proposed for IM/DD optical systems, where the modulation/demodulation processing takes advantage of the fast Hartley transform (FHT) algorithm. We realize the improved scheme in one symbol period while conventional Flip-OFDM scheme based on fast Fourier transform (FFT) in two consecutive symbol periods. So the complexity of many operations in improved scheme is half of that in conventional scheme, such as CP operation, polarity inversion and symbol delay. Compared to FFT with complex input constellation, the complexity of FHT with real input constellation is halved. The transmission experiment over 50-km SSMF has been realized to verify the feasibility of improved scheme. In conclusion, the improved scheme has the same BER performance with conventional scheme, but great superiority on complexity.

A New Generation of Micro Satellite Radiometers for Atmospheric Remote Sensing

NASA Astrophysics Data System (ADS)

He, jieying

2017-04-01

The need for low-cost, mission-flexible, and rapidly deployable space borne sensors that meet stringent performance requirements pervades the extreme weather monitoring programs, including especially the strong rainfall and typhoon. New technologies have enabled a novel approach toward this science observational goal, and in this paper we describe recent technology develop efforts to address the challenges above through the use of radiometers on a Micro-sized Microwave Atmospheric Satellite (Microsat), which operates in the type of constellation, and enable the capabilities of rapidly progressing. Recent work has involved the design and development of highly integrated radiometer component technologies that would enable the realization of a high-performance, multi-band sounder that would conform to the 3U CubeSat size (10 x 10 x 30 cm), weight, and power requirements. This paper partly focuses on the constellation to realize a scalable CubeSat-based system that will pave the path towards improved revisit rates over critical earth regions, and achieve state-of-the-art performance relative to current systems with respect to spatial, spectral, and radiometric resolution. As one of the important payloads on the platform, sub-millimeter radiometer is advised to house for providing atmospheric and oceanographic information all weather and all day. The first portion of the radiometer comprises a horn-fed reflector antenna, with a full-width at half-maximum (FWHM) beamwidth of 1.2°. Hence, the scanned beam has an approximate footprint diameter of 9.6 km at nadir incidence from a nominal altitude of 500 km. The antenna system is designed for a minimum 95% beam efficiency. Approximately 98 pixels are sampled for every scanning line, which covers a range of 1500km. The period of a round is about 94.47 minutes and re-visit period is four days. For the radiometer, which is a passive cross-track-scanning microwave spectrometer operating near the 118.75-GHz oxygen absorption line and 183 water vapor line for more than 100 channels based on high-speed digital processing technique, with a calibration accuracy of 0.5K for each channel to ensure the capability of temperature and ice-cloud retrievals. To meet the requirements of spatial and temporal specifications, a primarily concept of 41 Microsats in constellation are considered to achieve the retrievals in the resolution of 10km and 10 minutes.

Focal plane for the next generation of earth observation instruments

NASA Astrophysics Data System (ADS)

Pranyies, P.; Toubhans, I.; Badoil, B.; Tanguy, F.; Descours, Francis

2017-09-01

Sodern is the French focal plane provider for Earth Observation (EO) satellites. Since the 1980's, Sodern has played an active role first in the SPOT program. Within the two-spacecraft constellation Pleiades 1A/1B over the next years, Sodern introduced advanced technologies as Silicon Carbide (SiC) focal plane structure and multispectral strip filters dedicated to multiple-lines detectors.

Opening the archive: how free data has enabled the science and monitoring promise of Landsat

Treesearch

Michael A. Wulder; Jeffrey G. Masek; Warren B. Cohen; Thomas R. Loveland; Curtis E. Woodcock

2012-01-01

Landsat occupies a unique position in the constellation of civilian earth observation satellites, with a long and rich scientific and applications heritage. With nearly 40 years of continuous observation—since launch of the first satellite in 1972—the Landsat program has benefited from insightful technical specification, robust engineering, and the necessary...

The Role and Quality of Software Safety in the NASA Constellation Program

NASA Technical Reports Server (NTRS)

Layman, Lucas; Basili, Victor R.; Zelkowitz, Marvin V.

2010-01-01

In this study, we examine software safety risk in the early design phase of the NASA Constellation spaceflight program. Obtaining an accurate, program-wide picture of software safety risk is difficult across multiple, independently-developing systems. We leverage one source of safety information, hazard analysis, to provide NASA quality assurance managers with information regarding the ongoing state of software safety across the program. The goal of this research is two-fold: 1) to quantify the relative importance of software with respect to system safety; and 2) to quantify the level of risk presented by software in the hazard analysis. We examined 154 hazard reports created during the preliminary design phase of three major flight hardware systems within the Constellation program. To quantify the importance of software, we collected metrics based on the number of software-related causes and controls of hazardous conditions. To quantify the level of risk presented by software, we created a metric scheme to measure the specificity of these software causes. We found that from 49-70% of hazardous conditions in the three systems could be caused by software or software was involved in the prevention of the hazardous condition. We also found that 12-17% of the 2013 hazard causes involved software, and that 23-29% of all causes had a software control. Furthermore, 10-12% of all controls were software-based. There is potential for inaccuracy in these counts, however, as software causes are not consistently scoped, and the presence of software in a cause or control is not always clear. The application of our software specificity metrics also identified risks in the hazard reporting process. In particular, we found a number of traceability risks in the hazard reports may impede verification of software and system safety.

76 FR 66054 - Exelon Corporation Constellation Energy Group, Inc.; Notice of Filing

Federal Register 2010, 2011, 2012, 2013, 2014

2011-10-25

... DEPARTMENT OF ENERGY Federal Energy Regulatory Commission [Docket No. EC11-83-001] Exelon Corporation Constellation Energy Group, Inc.; Notice of Filing Take notice that, on October 11, 2011, Exelon Corporation and Constellation Energy Group, Inc. (Merger Applicants) submitted a filing styled as an answer in...