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1

Optical data communication for Earth observation satellite systems  

NASA Astrophysics Data System (ADS)

The current development status of optical communication engineering in comparison to the conventional microwave systems and the different configurations of the optical data communication for Earth observation satellite systems are described. An outlook to future optical communication satellite systems is given. During the last decade Earth observation became more and more important for the extension of the knowledge about our planet and the human influence on nature. Today pictures taken by satellites are used, for example, to discover mineral resources or to predict harvest, crops, climate, and environment variations and their influence on the population. A new and up to date application for Earth observation satellites can be the verification of disarmament arrangements and the control of crises areas. To solve these tasks a system of Earth observing satellites with sensors tailored to the envisaged mission is necessary. Besides these low Earth orbiting satellites, a global Earth observation system consists of at least two data relay satellites. The communication between the satellites will be established via Inter-Satellite Links (ISL) and Inter-Orbit Links (IOL). On these links, bitrates up to 1 Gbit/s must be taken into account. Due to the increasing scarcity of suitable frequencies, higher carrier frequencies must probably be considered, and possible interference with terrestrial radio relay systems are two main problems for a realization in microwave technique. One important step to tackle these problems is the use of optical frequencies for IOL's and ISL's.

Fischer, J.; Loecherbach, E.

1991-10-01

2

On the development of earth observation satellite systems  

NASA Technical Reports Server (NTRS)

Subsequent to the launching of the first LANDSAT by NASA, Japan has recognized the importance of data from earth observation satellites, has conducted studies, and is preparing to develop an independent system. The first ocean observation satellite will be launched in 1983, the second in 1985. The first land observation satellite is scheduled to be launched in 1987 and by 1990 Japan intends to have both land and ocean observation systems in regular operation. The association reception and data processing systems are being developed.

1977-01-01

3

Optical Data Communication for Earth Observation Satellite Systems.  

National Technical Information Service (NTIS)

The current development status of optical communication engineering in comparison to the conventional microwave systems and the different configurations of the optical data communication for Earth observation satellite systems are described. An outlook to...

J. Fischer E. Loecherbach

1991-01-01

4

The Earth Phenomena Observing System: Intelligent Autonomy for Satellite Operations  

NASA Technical Reports Server (NTRS)

Earth monitoring systems of the future may include large numbers of inexpensive small satellites, tasked in a coordinated fashion to observe both long term and transient targets. For best performance, a tool which helps operators optimally assign targets to satellites will be required. We present the design of algorithms developed for real-time optimized autonomous planning of large numbers of small single-sensor Earth observation satellites. The algorithms will reduce requirements on the human operators of such a system of satellites, ensure good utilization of system resources, and provide the capability to dynamically respond to temporal terrestrial phenomena. Our initial real-time system model consists of approximately 100 satellites and large number of points of interest on Earth (e.g., hurricanes, volcanoes, and forest fires) with the objective to maximize the total science value of observations over time. Several options for calculating the science value of observations include the following: 1) total observation time, 2) number of observations, and the 3) quality (a function of e.g., sensor type, range, slant angle) of the observations. An integrated approach using integer programming, optimization and astrodynamics is used to calculate optimized observation and sensor tasking plans.

Ricard, Michael; Abramson, Mark; Carter, David; Kolitz, Stephan

2003-01-01

5

SLR system improvement for GIOVE-A satellite observation  

NASA Astrophysics Data System (ADS)

Galileo system consists of 27 satellites distributed in three uniformly separated planes. At the end of 2005, one satellite, Galileo In-Orbit Validation Element-A (GIOVE-A), was launched as planned into an MEO with an altitude of 23,260 kilometers. Carrying a payload of rubidium clocks, signal-generation units, and a phase-array antenna of individual L-band elements. GIOVE-A started broadcasting on January 28, 2006, securing the frequencies allocated by the ITU for Galileo. Performance of the on-board atomic clocks, antenna infrastructure, and signal properties is evaluated through precise orbit determination, supported by Satellite Laser Ranging (SLR), an independent high-precision range measurement technique for orbit determination based on a global network of stations that measure the round-trip flight-time of ultra short laser pulses to satellites equipped with laser retro reflector arrays (LRAs). SLR provides instantaneous range measurements of millimeter-level precision which can be compiled to provide accurate orbits and to measure the on-board clock error. Given the importance of SLR data for the characterization of the GIOVE-A clocks, the Changchun SLR station in northeast China was selected among the Chinese stations contributing to the ILRS because it had demonstrated strong MEO satellite tracking; collocation with an existing International GPS Service station; and good weather conditions. This paper introduces the SLR system improvement for tracking GIOVE-A satellite in Changchun station. During the more than two months improvement, the new servo and encoder systems were installed, primary mirror, second mirror and some other mirrors have been cleaned and recoated, and the laser system was adjusted in order to improve the laser efficiency and output energy. The paper gives out the improvement results, and the GIOVE-A satellite observation results.

Zhao, You; Fan, Cunbo; Han, Xingwei; Yang, Dingjiang; Chen, Nianjiang; Xue, Feng; Geng, Lin

2008-03-01

6

Directional and photometric observations of artificial earth satellites using the U.K. Satellite Laser Ranging System  

Microsoft Academic Search

The recent use of the U.K. Satellite Laser Ranging System in nonranging mode to obtain astrometric and photometric observations of artificial satellites is described. It is found that the system is capable of obtaining a series of directional normal points of accuracy about 5 arcsec throughout a pass of a close-earth satellite. Simultaneous with the directional observations photometric observations were

G. M. Appleby

1990-01-01

7

A view finder control system for an earth observation satellite  

NASA Astrophysics Data System (ADS)

A real time TV view finder is used on-board a low earth orbiting (LEO) satellite to manually select targets for imaging from a ground station within the communication footprint of the satellite. The attitude control system on the satellite is used to steer the satellite using commands from the groundstation and a television camera onboard the satellite will then downlink a television signal in real time to a monitor screen in the ground station. The operator in the feedback loop will be able to manually steer the boresight of the satellite's main imager towards interested target areas e.g. to avoid clouds or correct for any attitude pointing errors. Due to a substantial delay (in the order of a second) in the view finding feedback loop and the narrow field of view of the main imager, the operator has to be assisted by the onboard attitude control system to stabilise and track the target area visible on the monitor screen. This paper will present the extended Kalman filter used to estimate the satellite's attitude angles using quaternions and the bias vector component of the 3-axis inertial rate sensors (gyros). Absolute attitude sensors (i.e. sun, horizon and magnetic) are used to supply the measurement vectors to correct the filter states during the view finder manoeuvres. The target tracking and rate steering reaction wheel controllers to accurately point and stabilise the satellite will be presented. The reference generator for the satellite to target attitude and rate vectors as used by the reaction wheel controllers will be derived.

Steyn, H.

2004-11-01

8

Observation of solar-system objects with the ISO satellite  

NASA Astrophysics Data System (ADS)

The ISO (Infrared Space Observatory) mission was an ESA earth-orbiting satellite devoted to the infrared observation of astronomical sources. The 60-cm helium-cooled telescope was launched in November 1995 and ended its life in May 1998. The satellite was equipped with 4 focal-plane instruments: a camera (CAM, 2.5-17 microns), a photometer (PHT, 2-200 microns) and two spectrometers, SWS (2.3-45 microns) and LWS (45-180 microns). A description of the ISO mission can be found in Kessler et al.(A&A 315 L27, 1996). Observations with ISO have been performed on all classes of solar-system objects. Several important discoveries have been obtained from the ISO data, in particular with the SWS instrument. A few of them are listed below: (1) a new determination of D/H on the four giant planets; (2) the discovery of an external source of water in the stratospheres of the giant planets and Titan; (3) the detection of CO_2 in the stratospheres of Jupiter, Saturn and Neptune; (4) the detection of new hydrocarbons (CH_3C_2H, C_4H_2, C_6H_6, CH_3) in Saturn's stratosphere; (5) the detection of tropospheric water in Saturn; (6) the detection of CO_2 in comet Hale-Bopp at far heliocentric distances (4.6 AU); (7) the first detection of forsterite (Mg_2SiO_4) in the dust of comet Hale-Bopp; (7) the determination of the formation temperature of comets Hale-Bopp and Hartley 2 (27 K and 35 K respectively) from the measurement of the ortho-para ratio in their H_2O nu _3 emission lines. In addition, ISO spectra of Titan, Io and the other galilean satellites, and asteroids were also recorded; IR photometry was achieved on Pluto, distant comets and zodiacal light. Preliminary results can be found in Crovisier et al. (A&A 315 L385, 1996; Science 275 1904, 1996), Encrenaz et al. (A&A 315 L397, 1996; A&A 333 L43, 1998), de Graauw et al. (A&A 321 L13, 1997), Feuchtgruber et al. (Nature 389 159, 1997), Griffin et al. (A&A 315 L389, 1996), Davis et al. (A&A 315 L393, 1996), Reach et al. (A&A 315 L381, 1996), Bezard et al. (A&A 334 L41, 1998) and Coustenis et al. (A&A 336 L85, 1998).

Encrenaz, Therese

1998-09-01

9

Satellite Altimetry for a Global Ocean Observing System  

NASA Technical Reports Server (NTRS)

Space-age technologies have made satellite remote sensing a powerful new tool to study the Earth on a global scale. However, the opacity of the ocean to electromagnetic sensing has limited spaceborne measurements to the properties of the surface layer of the ocean (such as sea surface temperature and color). The radar altimetric measurement of the height of the sea surface relative to the geoid, the dynamic topography of the ocean, is a very useful quantity for studying the circulation of the ocean. The ability of measuring dynamic topography from space makes satellite altimetry a uniquely useful remote sensing technique because dynamic topography reflects oceanic processes not only at the surface but at depths as well. A simple analysis shows that a one centimeter tilt in the dynamic topography is associated with a mass transport of 1-7 Sv (1Sv= 1 million tons per second) in the open ocean depending on the vertical distribution of current velocity. Such a magnitude is an appreciable fraction of the transport of the Florida Current (circa 30 Sv), for instance. TOPEX/POSEIDON has demonstrated the capability of measuring the time variation of sea level with accuracy approaching to 2 cm when the data are averaged over boxes with several hundred kilometers on each side. The data set has been used for studying ocean circulation phenomena with a wide range of scales, ranging from fast-changing barotropic variability to seasonal and interannual variability such as El Nino and La Nina. The long record of precise measurement of global sea level has also showed great promise for monitoring the variation of mean sea level, an effective indicator of global climate change. Continuation of satellite altimetry missions with capability matching or better than that of TOPEX/POSEIDON should be included as a key component of a Global Ocean Observing System. NASA and CNES have committed to continuing the measurement of TOPEX/POSEIDON with a series of follow-on missions called Jason. The first of the series, Jason-1, is scheduled for launch in May, 2000. Such a series of missions will provide a key data stream for both research and practical applications and benefit the objectives of global programs such as CLIVAR and GODAE.

Fu, Lee-Lueng

2000-01-01

10

NASDA's earth observation satellite data archive policy for the earth observation data and information system (EOIS)  

NASA Technical Reports Server (NTRS)

NASDA's new Advanced Earth Observing Satellite (ADEOS) is scheduled for launch in August, 1996. ADEOS carries 8 sensors to observe earth environmental phenomena and sends their data to NASDA, NASA, and other foreign ground stations around the world. The downlink data bit rate for ADEOS is 126 MB/s and the total volume of data is about 100 GB per day. To archive and manage such a large quantity of data with high reliability and easy accessibility it was necessary to develop a new mass storage system with a catalogue information database using advanced database management technology. The data will be archived and maintained in the Master Data Storage Subsystem (MDSS) which is one subsystem in NASDA's new Earth Observation data and Information System (EOIS). The MDSS is based on a SONY ID1 digital tape robotics system. This paper provides an overview of the EOIS system, with a focus on the Master Data Storage Subsystem and the NASDA Earth Observation Center (EOC) archive policy for earth observation satellite data.

Sobue, Shin-ichi; Yoshida, Fumiyoshi; Ochiai, Osamu

1996-01-01

11

Earth observing satellite: Understanding the Earth as a system  

NASA Technical Reports Server (NTRS)

There is now a plan for global studies which include two very large efforts. One is the International Geosphere/Biosphere Program (IGBP) sponsored by the International Council of Scientific Unions. The other initiative is Mission to Planet Earth, an unbrella program for doing three kinds of space missions. The major one is the Earth Observation Satellite (EOS). EOS is large polar orbiting satellites with heavy payloads. Two will be placed in orbit by NASA, one by the Japanese and one or two by ESA. The overall mission measurement objectives of EOS are summarized: (1) the global distribution of energy input to and energy output from the Earth; (2) the structure, state variables, composition, and dynamics of the atmosphere from the ground to the mesopause; (3) the physical and biological structure, state, composition, and dynamics of the land surface, including terrestrial and inland water ecosystems; (4) the rates, important sources and sinks, and key components and processes of the Earth's biogeochemical cycles; (5) the circulation, surface temperature, wind stress, sea state, and the biological activity of the oceans; (6) the extent, type, state, elevation, roughness, and dynamics of glaciers, ice sheets, snow and sea ice, and the liquid equivalent of snow in the global cryosphere; (7) the global rates, amounts, and distribution of precipitation; and (8) the dynamic motions of the Earth (geophysics) as a whole, including both rotational dynamics and the kinematic motions of the tectonic plates.

Soffen, Gerald

1990-01-01

12

Parachute satellites for earth observation  

NASA Astrophysics Data System (ADS)

The "parachute" concept presented here is a generic definition for earth observation systems essentially made of a reflector under which a detector associated with a telemetry antenna is suspended [D. Massonnet, (Applicant), Satellite, method and a fleet of satellites for observing a celestial body, Patent 0509-1112, 2006. [1]; D. Massonnet, (Déposant), Satellite, procédé et flotte de satellites d'observation d'un corps céleste, Priorité 04-04327, 2004. [2

Massonnet, Didier

2008-07-01

13

Keck Adaptive Optics Observations of Neptune's Ring and Satellite Keck Adaptive Optics Observations of Neptune's Ring and Satellite System  

NASA Astrophysics Data System (ADS)

We observed Neptune, its satellites and ring system on UT 27 and 28 July 2002, with NIRC2 on the 10-m Keck II telescope at 2.2 micron. The total field of view was 10". Each image was integrated for 1 minute; on the first day we had a total of 18 frames, and 33 images on the second day, each spread out over a time interval of 1-2 hours. The complete Adams and Le Verrier rings are visible on each day, after combining all images. In the regions away from the ring arcs, we find that the Le Verrier ring is brighter (up to 20-40%) than the Adams ring. The ring arcs are readily apparent in combinations of the data that take into account Keplerian motion. The ring arc positions are in close agreement with Nicholson et al's (1995) result, as in HST/NICMOS images (Dumas et al. 2002). The Egalite ring has broadened even more since observed with HST/NICMOS in 1998, and is clearly the brightest ring arc. Liberte has decreased in intensity since Voyager and NICMOS. Courage was extremely faint in our images. The satellites Proteus, Larissa, Galatea and Despina are easily seen on individual frames. Thalassa is detected after properly shifting/rotating and adding several frames. This is the first time since the Voyager flybys that Thalassa is detected. Preliminary astrometric measurements suggest the satellites Larissa and Galathea, relative to Proteus, to be off from their nominal (JPL Horizons) positions by 0.3", and Despina by 0.1". Recent results indicate that Proteus is offset by 0.1" compared to Triton (Martins et al. 2003). Preliminary I/F values are 0.06 for Proteus, 0.045 for Larissa and Galatea, and 0.03 for Despina and Thalassa. These observations were supported by the National Science Foundation Science and Technology Center for Adaptive Optics, managed by the University of California at Santa Cruz under cooperative agreement No. AST-9876783

de Pater, I.; Gibbard, S.; Martin, S.; Marchis, F.; Roe, H. G.; Macintosh, B.

2003-05-01

14

Candidate Configuration Trade Study, Stellar-Inertial Measurement Systems (Sims) for an Earth Observation Satellite (Eos).  

National Technical Information Service (NTIS)

The results of analytical and simulation studies of the stellar-inertial measurement system (SIMS) for an earth observation satellite are presented. Subsystem design analyses and sensor design trades are reported. Three candidate systems are considered: (...

G. Ogletree J. Coccoli M. Smith R. Mckern R. White

1972-01-01

15

Tropospheric Emission Spectrometer (TES) for the Earth Observing System (EOS) CHEM Satellite  

NASA Technical Reports Server (NTRS)

The Tropospheric Emission Spectrometer (TES) is an imaging infrared Fourier transform spectrometer scheduled to be launched into polar sun-synchronous orbit on the Earth Observing System (EOS) CHEM satellite in December 2002.

Beer, R.; Glavich, T.; Rider, D.

2000-01-01

16

World Weather Watch: Global Observing System - Satellite sub-System. Information on the Application of Meteorological Satellite Data in Routine Operations and Research: Abstracts, Annual Summaries and Bibliographies.  

National Technical Information Service (NTIS)

Contributions from countries participating in the World Weather Watch program are listed. Emphasis is on the Global Observing System: Satellite sub-system. Bibliographic information and an abstract of each contribution are provided.

1978-01-01

17

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

NASA Technical Reports Server (NTRS)

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.

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

2013-01-01

18

Korea Earth Observation Satellite Program  

Microsoft Academic Search

via Korea Aerospace Research Institute (KARI) as the prime contractor in the area of Korea earth observation satellite program to enhance Korea's space program development capability. In this paper, Korea's on-going and future earth observation satellite programs are introduced: KOMPSAT- 1 (Korea Multi Purpose Satellite-1), KOMPSAT-2 and Communication, Broadcasting and Meteorological Satellite (CBMS) program. KOMPSAT-1 satellite successfully launched in December

Myung-Jin Baek; Zeen-Chul Kim

2002-01-01

19

Assimilation of Satellite Ozone Observations  

NASA Technical Reports Server (NTRS)

This talk will discuss assimilation of ozone data from satellite-borne instruments. Satellite observations of ozone total columns and profiles have been measured by a series of Total Ozone Mapping Spectrometer (TOMS), Solar Backscatter Ultraviolet (SBUV) instruments, and more recently by the Global Ozone Monitoring Experiment. Additional profile data are provided by instruments on NASA's Upper Atmosphere Research Satellite and by occultation instruments on other platforms. Instruments on Envisat' and future EOS Aura satellite will supply even more comprehensive data about the ozone distribution. Satellite data contain a wealth of information, but they do not provide synoptic global maps of ozone fields. These maps can be obtained through assimilation of satellite data into global chemistry and transport models. In the ozone system at NASA's Data Assimilation Office (DAO) any combination of TOMS, SBUV, and Microwave Limb sounder (MLS) data can be assimilated. We found that the addition of MLS to SBUV and TOMS data in the system helps to constrain the ozone distribution, especially in the polar night region and in the tropics. The assimilated ozone distribution in the troposphere and lower stratosphere is sensitive also to finer changes in the SBUV and TOMS data selection and to changes in error covariance models. All results are established by comparisons of assimilated ozone with independent profiles from ozone sondes and occultation instruments.

Stajner, I.; Winslow, N.; Wargan, K.; Hayashi, H.; Pawson, S.; Rood, R.

2003-01-01

20

Data Dissemination System Status and Plan for Jaxa's Earth Observation Satellite Data  

NASA Astrophysics Data System (ADS)

1. INTRODUCTION JAXA is Japan's national aerospace agency and responsible for research, technology development and the launch of satellites into orbit, and is involved in many more advanced missions, such as asteroid exploration and possible manned exploration of the Moon. Since 1978, JAXA started to disseminate earth observation data acquired by satellites to researchers and those data scene became more than two Million scenes in 2011. This paper focuses on the status and future plan for JAXA's Data Dissemination System for those data. 2. STATUS JAXA is Japan's national aerospace agency and responsible for research, technology development and the launch of satellites into orbit. In October 1978, JAXA opened the Earth Observation Center (EOC) and started to archive and disseminate earth observation data acquired by multiple satellites. 2.1. Target data Currently, the disseminated data includes "JAXA's satellite/sensor data" and "non-JAXA's satellite/sensor data", as shown in Table 2-1. In 2011, the total disseminated data scene became more than two Million scenes. 2.2. Data Dissemination Guideline The JAXA basic data dissemination guideline is a free for researchers and specific agencies. JAXA has two approaches for dissemination. One is that the data is distributed for specific agencies by Mission Operation Systems (MOS). Each project has its own MOS, for example, GCOM-W1 has a GCOM-W1 MOS. Another is that the data is disseminated for many researchers by Data Distribution Systems. Now JAXA has three Data Distribution systems, EOIS, AUIG and GCOM-W1DPSS. Table 2-1 : Disseminated earth observation data from JAXA's facility Satellite Sensor Processing Level ALOS AVNIR-2 Level 1 PRISM Level 1 PALSAR Level 1 TRMM PR Level 1, 2, 3 CMB Level 1, 2, 3 TMI Level 1, 2, 3 VIR Level 1, 2, 3 Aqua AMSR-E Level 1, 2, 3 ADEOS-II AMSR Level 1, 2, 3 GLI-1km Level 1, 2, 3 GLI-250m Level 1, 2, 3 JERS-1 OSW Level 0, 1, 2 OVN Level 0, 1, 2, 5 SAR Level 1, 2 ADEOS AVNIR Level 1 OCTS Level 1, 2, 3 MOS-1b, -1 MES Level 0, 1, 2 VTI Level 0, 1, 2 GOSAT TANSO Level 1, 2, 3, 4 3. FUTURE PLAN For global earth observation spacecrafts, JAXA is now developing two dissemination systems, G-Portal and CATS-I. G-Portal will replace the EOIS and GCOM-W1DPSS including ALOS catalogue in AUIG. Users will be able to get the products of several spacecrafts in one stop service. G-Portal will be main dissemination system of the products for researches in GPM, GCOM-C1 and EarthCARE era. Other hand, CATS-I will disseminate Earth Observation product's catalogue for Japanese domestic key agencies, for example, Cabinet Office. CATS-I will also disseminate the catalogue for world key agencies and harvest the catalogue from other agencies with Catalogue Service for Web (CSW). JAXA will enlarge these G-Portal and CATS-I for future earth observation spacecrafts and these systems will be meet the demands of future users.

Fuda, M.; Miura, S.

2012-12-01

21

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

NASA Technical Reports Server (NTRS)

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.

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

2013-01-01

22

On the Use of Linearized Measurements from Satellite Observing Systems for Global Air Quality Forecasting  

NASA Astrophysics Data System (ADS)

As satellites are at the forefront in numerical weather prediction (NWP), future observations of tropospheric constituents from geostationary satellites will play a major role in regional-to-global air quality forecasting (AQF) systems. These observations provide a wealth of information that fully complements current AQF capability. However, the potential for higher spatio-temporal and spectral resolution of these observations entails a more efficient and practical AQF system that can handle and effectively assimilate the large volume of data in operational mode. This includes a reasonably accurate radiative transfer model (RTM) within the AQF system to calculate the observation operator across multiple spectral measurements. In addition, some practical forms of reducing the data without significant loss of information must be implemented for computational expediency. Here, we explore the applicability of using a reduced form of linearized measurements as input to the AQF system. In particular, we revisit the concept of using the Jacobians, which are calculated nonetheless during the retrieval of these constituents, in lieu of a full RTM calculation within the AQF system. A singular-value-decomposition of the Jacobian can then be carried out for each measurement to reduce the volume of data to be assimilated. This concept serves as a practical alternative to conventional approaches like full radiance or retrieval data assimilation. We demonstrate the applicability of this concept using the radiance measurements from the NASA/Terra Measurement of Pollution In The Troposphere instrument (MOPITT) and the corresponding Jacobians from the MOPITTv4 retrieval algorithm. Assimilation experiments are carried out under an ensemble-based chemical data assimilation framework that mimics an advance AQF system. We show results of the assimilation and comparisons with results from a retrieval assimilation of the same data.

Arellano, A. F.; Edwards, D. P.; Deeter, M. N.

2009-12-01

23

Korea Earth Observation Satellite Program  

NASA Astrophysics Data System (ADS)

via Korea Aerospace Research Institute (KARI) as the prime contractor in the area of Korea earth observation satellite program to enhance Korea's space program development capability. In this paper, Korea's on-going and future earth observation satellite programs are introduced: KOMPSAT- 1 (Korea Multi Purpose Satellite-1), KOMPSAT-2 and Communication, Broadcasting and Meteorological Satellite (CBMS) program. KOMPSAT-1 satellite successfully launched in December 1999 with Taurus launch vehicle. Since launch, KOMPSAT-1 is downlinking images of Korea Peninsular every day. Until now, KOMPSAT-1 has been operated more than 2 and half years without any major hardware malfunction for the mission operation. KOMPSAT-1 payload has 6.6m panchromatic spatial resolution at 685 km on-orbit and the spacecraft bus had NASA TOMS-EP (Total Ozone Mapping Spectrometer-Earth Probe) spacecraft bus heritage designed and built by TRW, U.S.A.KOMPSAT-1 program was international co-development program between KARI and TRW funded by Korean Government. be launched in 2004. Main mission objective is to provide geo-information products based on the multi-spectral high resolution sensor called Multi-Spectral Camera (MSC) which will provide 1m panchromatic and 4m multi-spectral high resolution images. ELOP of Israel is the prime contractor of the MSC payload system and KARI is the total system prime contractor including spacecraft bus development and ground segment. KARI also has the contract with Astrium of Europe for the purpose of technical consultation and hardware procurement. Based on the experience throughout KOMPSAT-1 and KOMPSAT-2 space system development, Korea is expecting to establish the infrastructure of developing satellite system. Currently, KOMPSAT-2 program is in the critical design stage. are scheduled to launch in 2008 and in 2014, respectively. The mission of CBMS consists of two areas. One is of space technology test for the communications mission, and the other is of a real- time environmental observation for meteorological mission on the geosynchronous orbit for public services. The CBMS is expected to weigh about 2 ~ 2.5 tons, and 6 channels of Ka-band and S- band transponder are equipped for communications service and observation payloads such as meteorological and ocean sensors. To increase the reliability of the first CBMS, a cooperative development with advanced foreign companies of the space business is being considered.

Baek, Myung-Jin; Kim, Zeen-Chul

24

Design and observations of satellite laser ranging system for daylight tracking at Shanghai Observatory  

Microsoft Academic Search

The first satellite laser ranging system for daylight tracking in China was set up at Shanghai Observatory, Chinese Academy\\u000a of Sciences. Both false alarm probability due to strong background noises and detection probability of the laser returns with\\u000a single photon level from satellite in daylight for our system are analysed. The system design and performance characteristics\\u000a of subsystems, adopted techniques

Fumin Yang; Chikun Xiao; Wanzhen Chen; Zhongping Zhang; Detong Tan; Xiangdong Gong; Juping Chen; Huang Li; Jianhua Zhang

1999-01-01

25

Dynamical and observational constraints on satellites in the inner Pluto-Charon system  

NASA Technical Reports Server (NTRS)

It is not known if Pluto has other satellites besides its massive partner Charon. In the past, searches for additional satellites in the Pluto-Charon system have extended from the solar-tidal stability boundary (approximately 90 arcsec from Pluto) inward to about 1 arcsec from Pluto. Here we further explore the inner (i.e., less than 10 arcsec) region of the Pluto-Charon system to determine where additional satellites might lie. In particular, we report on (1) dynamical simulations to delineate the region where unstable orbits lie around Charon, (2) dynamical simulations which use the low orbital eccentricity of Charon to constrain the mass of any third body near Pluto, and (3) analysis of Hubble Space Telescope (HST) archival images to search for satellites in the inner Pluto-Charon system. Although no objects were found, significant new constraints on bodies orbiting in the inner Pluto-Charon system were obtained.

Stern, S. Alan; Parker, Joel William; Duncan, Martin J.; Snowdall, J. Clark, Jr.; Levison, Harold F.

1994-01-01

26

An Attitude Control System for SumbandilaSAT an Earth Observation Satellite  

NASA Astrophysics Data System (ADS)

This paper describes the attitude determination and control system to support the multi-spectral earth observation main payload of the SumbandilaSAT microsatellite. The satellite has only a single main Y- body mounted solar panel and the attitude control system must ensure a nominal sun-pointed attitude under all non-imaging conditions during the sunlit part of the orbit. The control actuators employed are 3- axis magnetic torquer rods and reaction wheels. During initial detumbling and safe mode operations a simple new magnetic control law is used to bring the satellite to a sun-pointed Y-spinning attitude for maximum solar power collection. From this sun-pointed, spinning attitude an intermediate control mode is entered when the Y-reaction wheel is utilised as a momentum wheel, to absorb the body spin rate and to inertially stabilise the angular momentum vector towards the sun direction. During the intermediate mode the magnetic rods are used to maintain the momentum vector size and direction and to do nutation damping. The pitch angle is also controlled using the Y-wheel, to keep the main imager payload as close as possible to an earth-pointed attitude and to thermally stabilise the imager telescope. The final and nominal attitude control mode is entered when a zero biased 3-axis reaction wheel controller is enabled, for: 1) sun tracking for optimal solar power collection, 2) target tracking during viewfinder use or during imaging download communication with a ground station and 3) pushbroom imager scanning with a forward motion compensation capability. During the nominal mode the magnetic rods are used to dump the angular momentum from the reaction wheels during sun tracking periods. A short introduction to the Sumbandila satellite will be given. All the control modes, the attitude sensors and estimators utilised, will be introduced in the paper. Specifically, a unique agile viewfinder control mode to manually select targets for subsequent high resolution image scanning, when a control ground station is available within the communication footprint of the satellite, will be explained more thoroughly.

Steyn, W. H.

2008-08-01

27

A regional CO2 observing system simulation experiment for the ASCENDS Satellite Mission  

NASA Astrophysics Data System (ADS)

Top-down estimates of the spatiotemporal variations in emissions and uptake of CO2 will benefit from the increasing measurement density brought by recent and future additions to the suite of in situ and remote CO2 measurement platforms. In particular, the planned NASA Active Sensing of CO2 Emissions over Nights, Days, and Seasons (ASCENDS) satellite mission will provide greater coverage in cloudy regions, at high latitudes, and at night than passive satellite systems, as well as high precision and accuracy. In a novel approach to quantifying the ability of satellite column measurements to constrain CO2 fluxes, we use a portable library of footprints (surface influence functions) generated by the WRF-STILT Lagrangian transport model in a regional Bayesian synthesis inversion. The regional Lagrangian framework is well suited to make use of ASCENDS observations to constrain fluxes at high resolution, in this case at 1° latitude × 1° longitude and weekly for North America. We consider random measurement errors only, modeled as a function of mission and instrument design specifications along with realistic atmospheric and surface conditions. We find that the ASCENDS observations could potentially reduce flux uncertainties substantially at biome and finer scales. At the 1° × 1°, weekly scale, the largest uncertainty reductions, on the order of 50%, occur where and when there is good coverage by observations with low measurement errors and the a priori uncertainties are large. Uncertainty reductions are smaller for a 1.57 ?m candidate wavelength than for a 2.05 ?m wavelength, and are smaller for the higher of the two measurement error levels that we consider (1.0 ppm vs. 0.5 ppm clear-sky error at Railroad Valley, Nevada). Uncertainty reductions at the annual, biome scale range from ∼40% to ∼75% across our four instrument design cases, and from ∼65% to ∼85% for the continent as a whole. Our uncertainty reductions at various scales are substantially smaller than those from a global ASCENDS inversion on a coarser grid, demonstrating how quantitative results can depend on inversion methodology. The a posteriori flux uncertainties we obtain, ranging from 0.01 to 0.06 Pg C yr-1 across the biomes, would meet requirements for improved understanding of long-term carbon sinks suggested by a previous study.

Wang, J. S.; Kawa, S. R.; Eluszkiewicz, J.; Baker, D. F.; Mountain, M.; Henderson, J.; Nehrkorn, T.; Zaccheo, T. S.

2014-05-01

28

Preliminary design of a satellite observation system for Space Station Freedom  

NASA Technical Reports Server (NTRS)

Degobah Satellite Systems (DSS), in cooperation with the University Space Research Association (USRA), NASA - Johnson Space Center (JSC), and the University of Texas, has completed the preliminary design of a satellite system to provide inexpensive on-demand video images of all or any portion of Space Station Freedom (SSF). DSS has narrowed the scope of the project to complement the work done by Mr. Dennis Wells at Johnson Space Center. This three month project has resulted in completion of the preliminary design of AERCAM, the Autonomous Extravehicular Robotic Camera, detailed in this design report. This report begins by providing information on the project background, describing the mission objectives, constraints, and assumptions. Preliminary designs for the primary concept and satellite subsystems are then discussed in detail. Included in the technical portion of the report are detailed descriptions of an advanced imaging system and docking and safing systems that ensure compatibility with the SSF. The report concludes by describing management procedures and project costs.

Cabe, Greg (editor); Gallagher, Chris; Wilson, Brian; Rehfeld, James; Maurer, Alexa; Stern, Dan; Nualart, Jaime; Le, Xuan-Trang

1992-01-01

29

The Earth Observing System Microwave Limb Sounder (EOS MLS) on the Aura Satellite  

NASA Technical Reports Server (NTRS)

The Earth Observing System Microwave Limb Sounder measures several atmospheric chemical species (OH, HO2, H2O, O3, HCl, ClO, HOCl, BrO, HNO3, N2O, CO, HCN, CH3CN, volcanic SO2), cloud ice, temperature, and geopotential height to improve our understanding of stratospheric ozone chemistry, the interaction of composition and climate, and pollution in the upper troposphere. All measurements are made simultaneously and continuously, during both day and night. The instrument uses heterodyne radiometers that observe thermal emission from the atmospheric limb in broad spectral regions centered near 118, 190, 240, and 640 GHz, and 2.5 THz. It was launched July 15, 2004 on the National Aeronautics and Space Administration's Aura satellite and started full-up science operations on August 13, 2004. An atmospheric limb scan and radiometric calibration for all bands are performed routinely every 25 s. Vertical profiles are retrieved every 165 km along the suborbital track, covering 82 S to 82 N latitudes on each orbit. Instrument performance to date has been excellent; data have been made publicly available; and initial science results have been obtained.

Waters, Joe W.; Froidevaux, Lucien; Harwood, Robert S.; Jarnot, Robert F.; Pickett, Herbert M.; Read, William G.; Siegel, Peter H.; Cofield, Richard E.; Filipiak, Mark J.; Flower, Dennis A.; Holden, James R.; Lau, Gary K.; Livesey, Nathaniel J.; Manney, Gloria L; Pumphrey, Hugh C.; Santee, Michelle L.; Wu, Dong L.; Cuddy, David T.; Lay, Richard R.; Loo, Mario S.; Perun, Vincent S.; Schwartz, Michael J.; Stek, Paul C.; Thurstans, Robert P.; Boyles, Mark A.

2006-01-01

30

Astrometry of natural satellites: improving the dynamics of planetary systems with old observations.  

NASA Astrophysics Data System (ADS)

A new astrometric reduction of old photographic plates, benefiting from modern technologies such as sub-micrometric scanners associated with a reduction using accurate catalogues (UCAC at the present time and GAIA in a near future), provides improved knowledge of the orbital motion of planetary satellites.In the framework of an international collaboration first, and in the FP7 ESPaCE european project afterward, U.S. Naval Observatory plates were digitized with the new generation DAMIAN scanning machine of the Royal Observatory of Belgium. The procedure was applied to a few hundred photographic plates of the Galilean satellites covering the years 1967-1998, and of the Martian satellites covering the years 1967-1997. We provide results with an accuracy better than 70 mas in (RA,Dec) positions of the Galilean moons, and better than 60 mas in (RA,Dec) positions of the Martian satellites.Since the positions of Jupiter and Mars may be deduced from the observed (RA,Dec) positions of their satellites, we can also assess the accuracy of the ephemerides of Jupiter and Mars.

Robert, Vincent; Lainey, Valery; Arlot, Jean-Eudes

2014-05-01

31

Estimating zenith tropospheric delays from BeiDou navigation satellite system observations.  

PubMed

The GNSS derived Zenith Tropospheric Delay (ZTD) plays today a very critical role in meteorological study and weather forecasts, as ZTDs of thousands of GNSS stations are operationally assimilated into numerical weather prediction models. Recently, the Chinese BeiDou Navigation Satellite System (BDS) was officially announced to provide operational services around China and its neighborhood and it was demonstrated to be very promising for precise navigation and positioning. In this contribution, we concentrate on estimating ZTD using BDS observations to assess its capacity for troposphere remote sensing. A local network which is about 250 km from Beijing and comprised of six stations equipped with GPS- and BDS-capable receivers is utilized. Data from 5 to 8 November 2012 collected on the network is processed in network mode using precise orbits and in Precise Point Positioning mode using precise orbits and clocks. The precise orbits and clocks are generated from a tracking network with most of the stations in China and several stations around the world. The derived ZTDs are compared with that estimated from GPS data using the final products of the International GNSS Service (IGS). The comparison shows that the bias and the standard deviation of the ZTD differences are about 2 mm and 5 mm, respectively, which are very close to the differences of GPS ZTD estimated using different software packages. PMID:23552104

Xu, Aigong; Xu, Zongqiu; Ge, Maorong; Xu, Xinchao; Zhu, Huizhong; Sui, Xin

2013-01-01

32

A statistical comparison of deep convective cloud objects observed by an Earth Observing System satellite and simulated by a cloud-resolving model  

Microsoft Academic Search

The single scanner footprint (SSF) data product produced by the Clouds and the Earth's Radiant Energy System (CERES) instrument on board the Tropical Rainfall Measuring Mission (TRMM) satellite is used to diagnose 68 deep convective cloud objects observed in March 1998. The probability density functions (PDFs) of several observed and retrieved fields from the CERES SSF data product are used

Zachary A. Eitzen; Kuan-Man Xu

2005-01-01

33

A model, a heuristic and a decision support system to solve the earth observing satellites fleet scheduling problem  

Microsoft Academic Search

Creating an observation schedule is an important part of the earth observing satellites fleet management process. Even for a short term schedule already dozens of earth observing requests requiring several satellites have to be scheduled respecting complex constraints involving multidimensional resource capacities as well as request preferences. This paper first presented the earth observing satellites fleet scheduling problem, then formulated

Pei Wang; Peng Gao; Yuejin Tan

2009-01-01

34

PLHR emissions observed on satellites  

NASA Astrophysics Data System (ADS)

The aim of this paper is to review the most relevant characteristics of Power Line Harmonic Radiation (PLHR) that have been observed from satellites. Fifteen years ago, just after publications of results from the ARIEL-3 and -4 satellites, a large debate occurred about the influence of this phenomenon on natural wave emissions. New data were recently published concerning observations made from the low-altitude satellite AUREOL-3. These data indicate strong evidence for man-made influences on the ionosphere and magnetosphere. All the previous observations will be presented, with their main features. This paper also discusses the possible origin of magnetospheric lines that have been reported. The influence of man-made emissions will be evaluated and compared with other sources of energy in the Earth's environment.

Molchanov, Oleg; Parrot, Michel

1995-04-01

35

Diagnostic investigation of the climate system using satellite-observed and model- simulated spectral infrared radiances  

NASA Astrophysics Data System (ADS)

The Outgoing Longwave Radiation (OLR) is a critical component of the radiation energy budget at the top of the atmosphere. Its spectra carry rich information on radiatively active species at specific altitude levels, so that the OLR spectrum serves as a good indicator of the atmospheric and surface conditions. For the above reasons, satellite observed OLR spectra provide a rigorous test of state-of-art General Circulation Models (GCMs), with the discrepancy between simulated and observed radiances disclosing where the weakness of model lies. Over four years' Atmospheric Infrared Sound (AIRS) radiance data is now available. This data set provides a unique reference spectrum that can be used to assess GCM radiance simulations and thereby diagnose the characteristics of the present-day factors which influence the radiance. In this paper, we compare the statistics of satellite-observed and model-simulated OLR spectra on the diurnal and seasonal scales, and over both global and regional domains. For the satellite part, AIRS radiances are used. For the modeling part, a radiative transfer model with moderate spectral resolution (MODTRAN) is used to simulate outgoing radiances from the Geophysical Fluid Dynamics Lab (GFDL) global climate model. Assuming the observations are sound and the model-based radiances are calculated using an accurate radiation code, the discrepancy in radiances can be associated with the bias in the atmospheric states between model and reality through the "radiative Jacobians". One example of the application of this strategy is to pin down the cause(s) of the rather substantial clear-sky broadband OLR flux bias of GFDL model. With spectrally resolved radiances, the broadband flux bias may be attributed to different spectral regions that are sensitive to influential factors at particular altitude levels. Thus, insights are gained about the important physical variable(s) that may have caused the model bias. This establishes a complementary diagnosis to the comparison made at meteorological level.

Huang, Y.; Ramaswamy, V.

2006-12-01

36

An assessment of the FGGE satellite observing system during SOP-1. [Special Observing Period in First GARP Global Experiment  

NASA Technical Reports Server (NTRS)

The sensitivity of a Goddard Laboratory for Atmospheric Sciences global objective analysis cycle to the addition of FGGE level II-b data is assessed. The GOAS system comprises a predictive continuity provided by a model first-guess forecast integrated from a previous forecast and updated by data gathered in the interim. FGGE data originated in the Jan.-Mar. 1979 period and were acquired by rawinsondes, pilot balloons, surface stations, satellites, ships, and drifting buoys deployed during SOP-1. Focussing on 2-5 and 8-day forecasts, comparisons were made of the 6 hr forecast error at the 300 mb height in three experiments using all, no-satellite (NOSAT), and without rawinsondes or pilot balloons modes. Larger errors occurred in the case of NOSAT, while significant corrections to the GOAS predictions were noted using all the FGGE data. It was concluded that all forecasts were improved by inclusion of full FGGE data sets, including forecasting beyond one week.

Halem, M.; Kalnay, E.; Baker, W. E.; Atlas, R.

1982-01-01

37

Broadband Satellite Systems  

Microsoft Academic Search

Recently, the interest in broadband satellite multimedia (BSM) systems has grown rapidly. Advancements in transmission technology have led to the availability of low-cost satellite earth terminals. The superior remote access capabilities of satellite networks are foreseen to provide broadband services to geographically diverse user groups. The desire to support a wide range of broadband services in satellite networks implies that

Daniel Jozef Bem; Tadeusz W. Wieckowski; Ryszard J. Zielinski

2000-01-01

38

Operational Applications of Satellite Snowcover Observations  

NASA Technical Reports Server (NTRS)

The history of remote sensing of snow cover is reviewed and the following topics are covered: various techniques for interpreting LANDSAT and NOAA satellite data; the status of future systems for continuing snow hydrology applications; the use of snow cover observations in streamflow forecasts by Applications Systems Verification and Transfer participants and selected foreign investigators; and the benefits of using satellite snow cover data in runoff prediction.

Rango, A. (editor); Peterson, R. (editor)

1980-01-01

39

Geopotential Error Analysis from Satellite Gradiometer and Global Positioning System Observables on Parallel Architecture  

NASA Technical Reports Server (NTRS)

The recovery of a high resolution geopotential from satellite gradiometer observations motivates the examination of high performance computational techniques. The primary subject matter addresses specifically the use of satellite gradiometer and GPS observations to form and invert the normal matrix associated with a large degree and order geopotential solution. Memory resident and out-of-core parallel linear algebra techniques along with data parallel batch algorithms form the foundation of the least squares application structure. A secondary topic includes the adoption of object oriented programming techniques to enhance modularity and reusability of code. Applications implementing the parallel and object oriented methods successfully calculate the degree variance for a degree and order 110 geopotential solution on 32 processors of the Cray T3E. The memory resident gradiometer application exhibits an overall application performance of 5.4 Gflops, and the out-of-core linear solver exhibits an overall performance of 2.4 Gflops. The combination solution derived from a sun synchronous gradiometer orbit produce average geoid height variances of 17 millimeters.

Schutz, Bob E.; Baker, Gregory A.

1997-01-01

40

Ocean observer study: A proposed national asset to augment the future U.S. operational satellite system  

USGS Publications Warehouse

The next generation of U.S. polar orbiting environmental satellites, are now under development. These satellites, jointly developed by the Department of Defense (DoD), the Department of Commerce (DOC), and the National Aeronautics and Space Administration (NASA), will be known as the National Polar-orbiting Operational Environmental Satellite System (NPOESS). It is expected that the first of these satellites will be launched in 2010. NPOESS has been designed to meet the operational needs of the U.S. civilian meteorological, environmental, climatic, and space environmental remote sensing programs, and the Global Military Space and Geophysical Environmental remote sewing programs. This system, however, did not meet all the needs of the user community interested in operational oceanography (particularly in coastal regions). Beginning in the fall of 2000, the Integrated Program Office (IPO), a joint DoD, DOC, and NASA office responsible for the NPOESS development, initiated the Ocean Observer Study (OOS). The purpose of this study was to assess and recommend how best to measure the missing or inadequately sampled ocean parameters. This paper summarizes the ocean measurement requirements documented in the OOS, describes the national need to measure these parameters, and describes the satellite instrumentation required to make those measurements.

Cunningham, J. D.; Chambers, D.; Davis, C. O.; Gerber, A.; Helz, R.; McGuire, J. P.; Pichel, W.

2003-01-01

41

Satellite Observations of Tropospheric Chemistry  

NASA Technical Reports Server (NTRS)

The troposphere is an essential component of the earth's life support system as well as the gateway for the exchange of chemicals between different geochemical reservoirs of the earth. The chemistry of the troposphere is sensitive to perturbation from a wide range of natural phenomena and human activities. The societal concern has been greatly enhanced in recent decades due to ever increasing pressures of population growth and industrialization. Chemical changes within the troposphere control a vast array of processes that impact human health, the biosphere, and climate. A main goal of tropospheric chemistry research is to measure and understand the response of atmospheric composition to natural and anthropogenic perturbations, and to develop the capability to predict future change. Atmospheric chemistry measurements are extremely challenging due to the low concentrations of critical species and the vast scales over which the observations must be made. Available tropospheric data are mainly from surface sites and aircraft missions. Because of the limited temporal extent of aircraft observations, we have very limited information on tropospheric composition above the surface. This situation can be contrasted to the stratosphere, where satellites have provided critical and detailed chemical data on the global distribution of key trace gases.

Singh, Hanwant B.; Jacob, Daniel J.; Hipskind, R. Stephen (Technical Monitor)

2001-01-01

42

Flow-topography interactions in the northern California Current System observed from geostationary satellite data  

NASA Astrophysics Data System (ADS)

Data from Geostationary Operational Environmental Satellites are used to study the seasonal evolution of temperature fronts in the northern California Current System (CCS), focusing on the interactions with topographic features. Fronts first appear close to the coast in response to upwelling winds, moving offshore with the continuous input of energy to the system. Late in the upwelling season (after July), the upwelling front is persistently found over deeper waters south of Heceta Bank, Oregon, than north of it, suggesting that the equatorward jet separates from the shelf at Heceta Bank. Inshore of the upwelling front, weak gradients are found on the Bank. The interaction of the equatorward flow with Heceta Bank and Cape Blanco, Oregon, farther south, substantially increases the mesoscale activity and oceanic frontal habitat downstream to the south in the CCS, where fronts are persistently found greater than 100 km from the coast.

Castelao, Renato M.; Barth, John A.; Mavor, Timothy P.

2005-12-01

43

A comparison of mapped and measured total ionospheric electron content using global positioning system and beacon satellite observations  

Microsoft Academic Search

Total ionospheric electron contents (TEC) were measured by global positioning system (GPS) dual-frequency receivers developed by the Jet Propulsion Laboratory. The measurements included P-code (precise ranging code) and carrier phase data for six GPS satellites during multiple five-hour observing sessions. A set of these GPS TEC measurements were mapped from the GPS lines of sight to the line of sight

Gabor E. Lanyi; Titus Roth

1988-01-01

44

Future Satellite Observations of Solar Irradiance  

NASA Technical Reports Server (NTRS)

Required solar irradiance measurements for climate studies include those now being made by the Total Irradiance Monitor (TIM) and the Spectral Irradiance Monitor (SIM) onboard the SORCE satellite, part of the Earth Observing System fleet of NASA satellites. Equivalent or better measures of Total Solar Irradiance (TSI) and Spectral Solar Irradiance (SSI, 200 to 2000 nm) are planned for the post-2010 satellites of the National Polar-orbiting Operational Environmental Satellite System ("OESS). The design life of SORCE is 5 years, so a "Solar Irradiance Gap Filler" EOS mission is being planned for launch in the 2007 time frame, to include the same TSI and SSI measurements. Besides avoiding any gap, overlap of the data sources is also necessary for determination of possible multi-decadal trends in solar irradiance. We discuss these requirements and the impacts of data gaps, and data overlaps, that may occur in the monitoring of the critical solar radiative forcing.

Cahalan, R. F.; Rottman, G.; Woods, T.; Lawrence, G.; Harder, J.; McClintock, W.; Kopp, G.

2003-01-01

45

A comparison of mapped and measured total ionospheric electron content using global positioning system and beacon satellite observations  

NASA Technical Reports Server (NTRS)

Total ionospheric electron contents (TEC) were measured by global positioning system (GPS) dual-frequency receivers developed by the Jet Propulsion Laboratory. The measurements included P-code (precise ranging code) and carrier phase data for six GPS satellites during multiple five-hour observing sessions. A set of these GPS TEC measurements were mapped from the GPS lines of sight to the line of sight of a Faraday beacon satellite by statistically fitting the TEC data to a simple model of the ionosphere. The mapped GPS TEC values were compared with the Faraday rotation measurements. Because GPS transmitter offsets are different for each satellite and because some GPS receiver offsets were uncalibrated, the sums of the satellite and receiver offsets were estimated simultaneously with the TEC in a least squares procedure. The accuracy of this estimation procedure is evaluated indicating that the error of the GPS-determined line of sight TEC can be at or below 1 x 10 to the 16th el/sq cm. Consequently, the current level of accuracy is comparable to the Faraday rotation technique; however, GPS provides superior sky coverage.

Lanyi, Gabor E.; Roth, Titus

1988-01-01

46

Satellite system survivability  

SciTech Connect

Present U.S. military capability relies heavily on Earth satellites to maintain connectivity. The essential nature of these satellite systems has made them tempting targets to nuclear attack in wartime. The author reviews U.S. history in high-altitude nuclear device testing and nuclear effects testing on satellites, events in which he directly participated. Physics of the production of nuclear enhanced high-altitude electron belts are reviewed. The author discusses primary effects of the enhanced environment on satellite components. A glimpse into future satellite hardening reveals measures against developing directed energy weapons.

Shelton, F.H.

1983-01-01

47

Satellite power systems technology  

Microsoft Academic Search

The development emphasis of the next decade in electrical power systems for satellites will be to provide larger amounts of electrical power with dramatically improved power system performance. Reliability, survivability, adaptability, scalability and endurability will continue to be important power system technology considerations for most missions. This paper addresses increasing power trends seen for future satellite missions, describes the current

R. R. Barthelemy; L. D. Massie

1984-01-01

48

Satellite Observations of Tropospheric Ammonia  

NASA Astrophysics Data System (ADS)

Global high-spectral resolution (0.06 cm-1) nadir measurements from TES-Aura enable the simultaneous retrieval of a number of tropospheric pollutants and trace gases in addition to the TES standard operationally retrieved products (e.g. carbon monoxide, ozone). Ammonia (NH3) is one of the additional species that can be retrieved in conjunction with the TES standard products, and is important for local, regional, and global tropospheric chemistry studies. Ammonia emissions contribute significantly to several well-known environmental problems, yet the magnitude and seasonal/spatial variability of the emissions are poorly constrained. In the atmosphere, an important fraction of fine particulate matter is composed of ammonium nitrate and ammonium sulfate. These particles are statistically associated with health impacts. When deposited to ecosystems in excess, nitrogen, including ammonia can cause nutrient imbalances, change in ecosystem species composition, eutrophication, algal blooms and hypoxia. Ammonia is also challenging to measure in-situ. Observations of surface concentrations are rare and are particularly sparse in North America. Satellite observations of ammonia are therefore highly desirable. We recently demonstrated that tropospheric ammonia is detectable in the TES spectra and presented some corresponding preliminary retrievals over a very limited range of conditions (Beer et al., 2008). Presented here are results that expand upon these initial TES ammonia retrievals in order to evaluate/validate the retrieval results utilizing in-situ surface observations (e.g. LADCO, CASTNet, EPA /NC State) and chemical models (e.g. GEOS-Chem and CMAQ). We also present retrievals over regions of interest that have the potential to help further understand air quality and the active nitrogen cycle. Beer, R., M. W. Shephard, S. S. Kulawik, S. A. Clough, A. Eldering, K. W. Bowman, S. P. Sander, B. M. Fisher, V. H. Payne, M. Luo, G. B. Osterman, and J. R. Worden, First satellite observations of lower tropospheric ammonia and methanol, Geophysical Res. Letters, 35, L09801, doi:10.1029/2008GL033642, 2008.

Shephard, M. W.; Luo, M.; Rinsland, C. P.; Cady-Pereira, K. E.; Beer, R.; Pinder, R. W.; Henze, D.; Payne, V. H.; Clough, S.; Rodgers, C. D.; Osterman, G. B.; Bowman, K. W.; Worden, H. M.

2008-12-01

49

Measurements of Tropospheric NO2 in Romania Using a Zenith-Sky Mobile DOAS System and Comparisons with Satellite Observations  

PubMed Central

In this paper we present a new method for retrieving tropospheric NO2 Vertical Column Density (VCD) from zenith-sky Differential Optical Absorption Spectroscopy (DOAS) measurements using mobile observations. This method was used during three days in the summer of 2011 in Romania, being to our knowledge the first mobile DOAS measurements peformed in this country. The measurements were carried out over large and different areas using a mobile DOAS system installed in a car. We present here a step-by-step retrieval of tropospheric VCD using complementary observations from ground and space which take into account the stratospheric contribution, which is a step forward compared to other similar studies. The detailed error budget indicates that the typical uncertainty on the retrieved NO2tropospheric VCD is less than 25%. The resulting ground-based data set is compared to satellite measurements from the Ozone Monitoring Instrument (OMI) and the Global Ozone Monitoring Experiment-2 (GOME-2). For instance, on 18 July 2011, in an industrial area located at 47.03°N, 22.45°E, GOME-2 observes a tropospheric VCD value of (3.4 ± 1.9) × 1015 molec./cm2, while average mobile measurements in the same area give a value of (3.4 ± 0.7) × 1015 molec./cm2. On 22 August 2011, around Ploiesti city (44.99°N, 26.1°E), the tropospheric VCD observed by satellites is (3.3 ± 1.9) × 1015 molec./cm2 (GOME-2) and (3.2 ± 3.2) × 1015 molec./cm2 (OMI), while average mobile measurements give (3.8 ± 0.8) × 1015 molec./cm2. Average ground measurements over “clean areas”, on 18 July 2011, give (2.5 ± 0.6) × 1015 molec./cm2 while the satellite observes a value of (1.8 ± 1.3) × 1015 molec./cm2.

Constantin, Daniel-Eduard; Merlaud, Alexis; Van Roozendael, Michel; Voiculescu, Mirela; Fayt, Caroline; Hendrick, Francois; Pinardi, Gaia; Georgescu, Lucian

2013-01-01

50

The Earth observing system microwave limb sounder (EOS MLS) on the aura Satellite  

Microsoft Academic Search

The Earth Observing System Microwave Limb Sounder measures several atmospheric chemical species (OH, HO2, H2O, O3, HCl, ClO, HOCl, BrO, HNO3, N2O, CO, HCN, CH3CN, volcanic SO2), cloud ice, temperature, and geopotential height to improve our understanding of stratospheric ozone chemistry, the interaction of composition and climate, and pollution in the upper troposphere. All measurements are made simultaneously and continuously,

Joe W. Waters; Lucien Froidevaux; Robert S. Harwood; Robert F. Jarnot; Herbert M. Pickett; William G. Read; Peter H. Siegel; Richard E. Cofield; Mark J. Filipiak; Dennis A. Flower; James R. Holden; Gary K. Lau; Nathaniel J. Livesey; Gloria L. Manney; Hugh C. Pumphrey; Michelle L. Santee; Dong L. Wu; David T. Cuddy; Richard R. Lay; Mario S. Loo; Vincent S. Perun; Michael J. Schwartz; Paul C. Stek; Robert P. Thurstans; Mark A. Boyles; Kumar M. Chandra; Marco C. Chavez; Gun-Shing Chen; Bharat V. Chudasama; Randy Dodge; Ryan A. Fuller; Michael A. Girard; Jonathan H. Jiang; Yibo Jiang; Brian W. Knosp; Remi C. LaBelle; Jonathan C. Lam; Karen A. Lee; Dominick Miller; John E. Oswald; Navnit C. Patel; David M. Pukala; Ofelia Quintero; David M. Scaff; W. Van Snyder; Michael C. Tope; Paul A. Wagner; Marc J. Walch

2006-01-01

51

Antisunward net Birkeland current system deduced from the Oersted satellite observation  

Microsoft Academic Search

From the precise magnetic field measurements by the Oersted satellite at low altitudes over various local times, a distinct spatial variation at middle and low latitudes was detected in the eastward component residuals (DeltaBphi) after the subtraction of a geomagnetic main field model. The average DeltaBphi decreases on the dayside as latitude increases, and it increases on the nightside. That

S. Yamashita; T. Iyemori; S. Nakano; T. Kamei; T. Araki

2002-01-01

52

Antisunward net Birkeland current system deduced from the Oersted satellite observation  

Microsoft Academic Search

From the precise magnetic field measurements by the Oersted satellite at low altitudes over various local times, a distinct spatial variation at middle and low latitudes was detected in the eastward component residuals (?B?) after the subtraction of a geomagnetic main field model. The average ?B? decreases on the dayside as latitude increases, and it increases on the nightside. That

S. Yamashita; T. Iyemori; S. Nakano; T. Kamei; T. Araki

2002-01-01

53

Satellite system survivability  

NASA Astrophysics Data System (ADS)

Present U.S. military capability relies heavily on Earth satellites to maintain connectivity. The essential nature of these satellite systems has made them tempting targets to nuclear attack in wartime. The author reviews U.S. history in high-altitude nuclear device testing and nuclear effects testing on satellies, events in which he directly participated. Physics of the production of nuclear enhanced high-altitude electron belts are reviewed. The author discusses primary affects of the enhanced environment on satellite components. A glimpse into future satellite hardening reveals measures against developing directed energy weapons.

Shelton, F. H.

54

A Global Observing System for Mars: The dual satellite Mars Astrobiology and Climate Observatory (MACO)  

NASA Astrophysics Data System (ADS)

We summarize a planetary decadal survey white paper describing the rationale for and key elements of a dual satellite orbiting mission (DSM) concept called the Mars Astrobiology and Climate Observatory (MACO). MACO uses mm-wavelength satellite to satellite (sat-sat) occultations in combination with solar occultations (SO) to answer and strongly constrain many key lower and middle atmosphere Mars science questions previously considered unachievable from orbit. On the climate side, MACO would focus on the hydrological, dust and energy cycles of Mars. MACO would measure the transport of water in the present Martian climate, identify sources and sinks and constrain processes in order to better understand present and past Martian climate and glacial and subsurface water reservoirs. Dust-penetrating, satellite-to-satellite mm-wave occultations would profile water vapor to 3%, temperature to 0.4K, geopotential height of pressure to 10 m, line of sight winds to < 2 m/s and balanced winds via pressure gradients, as well turbulence and certain trace constituents with 60 meter diffraction limited vertical resolution and high precision extending down to the surface. A prototype mm-wave occultation instrument will be demonstrated in 2010 via high altitude aircraft to aircraft occultations. MACO will make coincident thermal IR and shortwave measurements to characterize airborne dust to understand dust storm initiation and evolution and how atmospheric dust concentrations are maintained in general. The combination of sensitivity, accuracy and vertical resolution from the satellite to satellite occultation is simply not possible with radiometers and will provide ~30,000 globally distributed near-entry probe quality profiles each Martian year profiling the boundary layer and exchange between the atmosphere and surface. A near-IR solar occultation instrument, such as the French SOIR or a derivative of the Canadian ACE FTIR instrument, would survey chemical trace species such as methane in the Martian atmosphere to look for signatures of subsurface processes related to possible habitable zones and life. MACO’s winds will be key in tracing plumes back to their source regions. Proposed near-surface ion-related heterogeneous chemistry will be assessed by profiling near surface concentrations of H2O2, H2O and dust to look for predicted enhancements in of H2O2 and how they vary with H2O and dust concentrations. MACO’s combined capabilities are a superset of the Mars Science Orbiter (MSO) recommended by the Calvin et al. (2007) report. MACO would fit as a moderate scale mission in the 2016 launch opportunity. Alternatively, since NASA and ESA have recently announced their intent to fly a single orbiter, trace gas mission in 2016, the MACO mm occultation receiver (which can also measure thermal emission and solar occultations) could be flown on that mission and the occultation transmitter could be carried on another mission flown by an international partner such as Japan or India.

Kursinski, E. R.; Lyons, J.; Newman, C.; Richardson, M. I.; Ward, D.; Otarola, A. C.

2009-12-01

55

Applications systems verification and transfer project. Volume 1: Operational applications of satellite snow cover observations: Executive summary. [usefulness of satellite snow-cover data for water yield prediction  

NASA Technical Reports Server (NTRS)

Both LANDSAT and NOAA satellite data were used in improving snowmelt runoff forecasts. When the satellite snow cover data were tested in both empirical seasonal runoff estimation and short term modeling approaches, a definite potential for reducing forecast error was evident. A cost benefit analysis run in conjunction with the snow mapping indicated a $36.5 million annual benefit accruing from a one percent improvement in forecast accuracy using the snow cover data for the western United States. The annual cost of employing the system would be $505,000. The snow mapping has proven that satellite snow cover data can be used to reduce snowmelt runoff forecast error in a cost effective manner once all operational satellite data are available within 72 hours after acquisition. Executive summaries of the individual snow mapping projects are presented.

Rango, A.

1981-01-01

56

Jupiter System Observer  

NASA Technical Reports Server (NTRS)

This slide presentation reviews the proposed mission for the Jupiter System Observer. The presentation also includes overviews of the mission timeline, science goals, and spacecraftspecifications for the satellite.

Senske, Dave; Kwok, Johnny

2008-01-01

57

The Effect of Environmental Conditions on Tropical Deep Convective Systems Observed from the TRMM Satellite  

NASA Technical Reports Server (NTRS)

This study uses measurements of radiation and cloud properties taken between January and August 1998 by three Tropical Rainfall Measuring Mission (TRMM) instruments, the Clouds and the Earth's Radiant Energy System (CERES) scanner, the TRMM Microwave Imager (TMI), and the Visible and InfraRed Scanner (VIRS), to evaluate the variations of tropical deep convective systems (DCS) with sea surface temperature (SST) and precipitation. This study finds that DCS precipitation efficiency increases with SST at a rate of approx. 2%/K. Despite increasing rainfall efficiency, the cloud areal coverage rises with SST at a rate of about 7%/K in the warm tropical seas. There, the boundary layer moisture supply for deep convection and the moisture transported to the upper troposphere for cirrus-anvil cloud formation increase by approx. 6.3%/K and approx. 4.0%/K, respectively. The changes in cloud formation efficiency, along with the increased transport of moisture available for cloud formation, likely contribute to the large rate of increasing DCS areal coverage. Although no direct observations are available, the increase of cloud formation efficiency with rising SST is deduced indirectly from measurements of changes in the ratio of DCS ice water path and boundary layer water vapor amount with SST. Besides the cloud areal coverage, DCS cluster effective sizes also increase with precipitation. Furthermore, other cloud properties, such as cloud total water and ice water paths, increase with SST. These changes in DCS properties will produce a negative radiative feedback for the earth's climate system due to strong reflection of shortwave radiation by the DCS. These results significantly differ from some previous hypothesized dehydration scenarios for warmer climates, and have great potential in testing current cloud-system resolving models and convective parameterizations of general circulation models.

Lin, Bing; Wielicki, Bruce A.; Minnis, Patrick; Chambers, Lin H.; Xu, Kuan-Man; Hu, Yongxiang; Fan, Tai-Fang

2005-01-01

58

Satellite diversity in mobile satellite CDMA systems  

Microsoft Academic Search

The paper addresses the exploitation of satellite diversity in a satellite mobile network. In particular, we focus on the impact of diversity on service availability and on system capacity, considering the forward link of a CDMA system with a multisatellite and multibeam architecture. The analysis includes the effects of path blockage, intrabeam and interbeam interference, imperfect power control, and fading

Carlo Caini; Giovanni Emanuele Corazza

2001-01-01

59

Satellite Multicarrier Demodulation System  

NASA Technical Reports Server (NTRS)

Proposed onboard signal processing system for communications satellites performs real-time conversion of multiple uplink (received) signals in single-channel-per-carrier, frequency-division-multiple-access (SCPC/FDMA) format to downlink (transmitted) signals in time-division-multiplexed (TDM) format. Conversion approach enhances use of allocated spectrum and reduces required effective isotropic radiated power at both transponder (satellite) and Earth stations. Equipment needed to implement scheme less complex and less expensive than time-division-multiple-access (TDMA) formats. More economical future satellite communication systems made possible through use of many small-capacity multiservice Earth terminals.

Budinger, James; Kwatra, Subhash C.; Jamale, Mohsin M.; Fernandez, John P.; Eugene, Linus P.

1994-01-01

60

Linking Regional Satellite Observations with Coupled Human-Ecological Systems in Global Drylands  

NASA Astrophysics Data System (ADS)

The African Sahel has attracted consistent attention since a series of droughts in the 1970s and 1980s caused widespread famine and land degradation (desertification). These events spawned international conventions and sustained development efforts to increase food security and reverse poverty for the local populations, and to arrest environmental degradation. Since 1985, several studies using satellite data have described a general “greening” in response to increased rainfall trends. However, some areas show more greening while others less greening than can be explained by precipitation alone (Glob. Env. Change 15- 2005). The debated question is how to explain the residual changes: management, policy, human adaptation, or something else? Placing results in an human-ecological framework could help answer this question. Providing a meaningful assessment will allow national and international agencies to evaluate the effectiveness of alternative approaches to poverty alleviation and environmental restoration in drylands at regional and global scales.

Hutchinson, C.; Reynolds, J. F.

2009-12-01

61

Global Earth observation using modern communications satellite techniques  

NASA Astrophysics Data System (ADS)

The various properties of geostationary and low Earth orbiting satellites are discussed. Main emphasis is given to satellite interconnection techniques, due to the importance of Interorbit and Intersatellite Links (IOL and ISL) in a global and efficient Earth observation satellite system. Conventional microwave as well as modern optical techniques are possible candidates for these links. In this frame, a High Power Diode Transmitter (HPDT) is presented. As an outlook to a future worldwide communication scenario the integration of Earth observation satellites in an information satellite (Infosat) system is raised.

Loecherbach, E.; Eckhardt, G.

1992-07-01

62

Measurements of tropospheric NO2 in Romania using a zenith-sky mobile DOAS system and comparisons with satellite observations.  

PubMed

In this paper we present a new method for retrieving tropospheric NO2 Vertical Column Density (VCD) from zenith-sky Differential Optical Absorption Spectroscopy (DOAS) measurements using mobile observations. This method was used during three days in the summer of 2011 in Romania, being to our knowledge the first mobile DOAS measurements peformed in this country. The measurements were carried out over large and different areas using a mobile DOAS system installed in a car. We present here a step-by-step retrieval of tropospheric VCD using complementary observations from ground and space which take into account the stratospheric contribution, which is a step forward compared to other similar studies. The detailed error budget indicates that the typical uncertainty on the retrieved NO2tropospheric VCD is less than 25%. The resulting ground-based data set is compared to satellite measurements from the Ozone Monitoring Instrument (OMI) and the Global Ozone Monitoring Experiment-2 (GOME-2). For instance, on 18 July 2011, in an industrial area located at 47.03°N, 22.45°E, GOME-2 observes a tropospheric VCD value of (3.4 ± 1.9) × 1015 molec./cm2, while average mobile measurements in the same area give a value of (3.4 ± 0.7) × 10(15) molec./cm2. On 22 August 2011, around Ploiesti city (44.99°N, 26.1°E), the tropospheric VCD observed by satellites is (3.3 ± 1.9) × 10(15) molec./cm2 (GOME-2) and (3.2 ± 3.2) × 10(15) molec./cm2 (OMI), while average mobile measurements give (3.8 ± 0.8) × 10(15) molec./cm2. Average ground measurements over "clean areas", on 18 July 2011, give (2.5 ± 0.6) × 10(15) molec./cm2 while the satellite observes a value of (1.8 ± 1.3) × 10(15) molec./cm2. PMID:23519349

Constantin, Daniel-Eduard; Merlaud, Alexis; Van Roozendael, Michel; Voiculescu, Mirela; Fayt, Caroline; Hendrick, François; Pinardi, Gaia; Georgescu, Lucian

2013-01-01

63

Earth resources satellite systems for flood monitoring  

NASA Technical Reports Server (NTRS)

The environmental satellites NOAA-2 and ERTS-1 observed flooding in United States' rivers such as the Mississippi during 1973. Combination of NOAA-2 observation frequency and the ERTS-1 resolution provides an adequate satellite system for monitoring floods. Several polar-orbiting satellites of the ERTS type could view flooded areas at a reasonably high resolution every three to five days. A high-resolution earth-synchronous satellite would further enhance flood mapping by providing observations whenever clouds are absent.

Mcginnis, D. F.; Rango, A.

1975-01-01

64

Satellite power system simulation  

Microsoft Academic Search

In order to furnish a useful tool for the power system preliminary sizing, a satellite power system simulator was developed. The simulator has a modular structure where each module implements the mathematical model of the system components (solar array, battery, voltage regulators etc.). The software allows both the verification of the rating co-ordination of all those parts composing the power

G. Colombo; U. Grasselli; A. De Luca; A. Spizzichino; S. Falzini

1997-01-01

65

AMOS Galaxy 15 Satellite Observations and Analysis  

NASA Astrophysics Data System (ADS)

In early April 2010, the Galaxy 15 geosynchronous satellite experienced an on-orbit anomaly. Even though the satellite's transmitters and articulating solar panel were still functioning, ground controllers lost the ability to command and maneuver the satellite. With its orbital position no longer maintained, Galaxy 15 began to drift eastward. This forced several other satellites to make collision avoidance maneuvers during the following months. Soon after the initial anomaly, Galaxy 15's operators predicted that the satellite’s reaction wheels would eventually become saturated, causing a loss of both spacecraft attitude and proper sunward orientation of the solar panels. This "off-pointing" event finally occurred in late December, ultimately leading to a depletion of Galaxy 15's batteries. This near-death experience had a fortunate side effect, however, in that it forced the satellite’s command unit to reboot and once again be able to both receive and execute ground commands. The satellite operators have since recovered control of the satellite. AMOS conducted non-resolved photometric observations of Galaxy 15 before, during and after these events. Similar observations were conducted of Galaxy 12, the nearly-identical replacement satellite. This presentation presents and discusses these temporal brightness signatures in detail, comparing the changing patterns in the observations to the known sequence of events.

Hall, D.

2011-09-01

66

Systems approach to developing a climate data record from satellite observations  

Microsoft Academic Search

A Climate Data Record (CDR) consists of a body of information of some observable of the Earth's climate that is of sufficient information content and accuracy to allow climate science to be performed with this record now and in the distant future. We examine the generation of a hyperspectral infrared CDR for the Atmospheric Infrared Sounder (AIRS) instrument as good

Steve E. Broberg; Thomas S. Pagano; Hartmut H. Aumann; Denis A. Elliott; Fred O'Callaghan

2010-01-01

67

Automatic derivation of earth observation products from satellite data within the Siberian Earth System Science Cluster (SIB-ESS-C)  

NASA Astrophysics Data System (ADS)

The Siberian Earth System Science Cluster (SIB-ESS-C) established at the University of Jena (Germany) is a spatial data infrastructure implementing standards published by the Open Geospatial Consortium (OGC) and the International Organization for Standardization (ISO) aimed at providing researchers with focus on Siberia with the technical means for data discovery, data access, data publication and data analysis in work with earth observation data. At the current development stage the SIB-ESS-C system comprises a federated metadata catalogue accessible through the SIB-ESS-C Web Portal or from any OGC-CSW compliant client. The Web Portal also contains a simple map-like visualization component which is currently being extended to a comprehensive visualization and analysis tool. The visualization component enables users to overlay different dataset found during a catalogue search. All data products are accessible as Web Mapping, Web Feature or Web Coverage Services allowing users to directly incorporate the data into their application. New developments aims on automatic registration and processing of raw earth observation data to derive permanently earth observation products. A data registry system within a whole process system including process chains to implement algorithms is currently designed. This will be extended with a system to process these incoming data automatically and permanently, depending on registered algorithms. Algorithms should know which input data is necessary and registered data should know which algorithms could be executed on it. This paper describes current developments as well as future ideas to build up a usefull and userfriendly access to satellite data, algorithms and therefrom derived products with state of the art web technologies and standards of the OGC.

Eberle, J.; Schmullius, C. C.

2011-12-01

68

A Regional Climate Model Evaluation System based on Satellite and other Observations  

Microsoft Academic Search

Regional climate models are a fundamental tool needed for downscaling global climate simulations and projections, such as those contributing to the Coupled Model Intercomparison Projects (CMIPs) that form the basis of the IPCC Assessment Reports. The regional modeling process provides the means to accommodate higher resolution and a greater complexity of Earth System processes. Evaluation of both the global and

P. Lean; J. Kim; D. E. Waliser; A. D. Hall; C. A. Mattmann; S. L. Granger; K. Case; C. Goodale; A. Hart; P. Zimdars; B. Guan; N. P. Molotch; S. Kaki

2010-01-01

69

AMOS Observations of NASA's IMAGE Satellite  

NASA Astrophysics Data System (ADS)

NASA's Imager for Magnetopause-to-Aurora Global Exploration (IMAGE) satellite stopped transmitting telemetry to ground stations in December 2005, after functioning for more than 5 years on Earth orbit. Before this loss of telemetry, the IMAGE satellite actively maintained a spin-stabilized attitude with spin axis perpendicular to the orbital plane and a nominal rotation rate of about 0.5 rpm. The spinning action served to both stabilize the satellite and keep the 250 m-long radial wire antennas of the satellite's Radio Plasma Imager under tension perpendicular to the satellite spin axis. After loss of telemetry, it was unclear whether the spacecraft remained in this spin-stabilized configuration, or whether it could continue to receive and execute up- linked commands. In late January and early February of 2006 the AMOS 3.6m Advanced Electro Optical System (AEOS) conducted an initial set of observations in an effort to help diagnose the state of the unresponsive spacecraft. The AEOS observations employed the Visible Imager (VisIm) instrument in the photometric I-band as well as the long-wavelength infrared (LWIR) imager. The wide field-of-view VisIm images clearly show the long radial wire antennas glinting in reflected sunlight during each revolution of the spinning spacecraft, creating a photometric signature characterized by large amplitude periodic variations. Analysis of concurrent AEOS LWIR observations indicates radiometric temperatures ranging from 250 to 310 Kelvin, with the higher temperatures occurring when more of the continuously-sunlit portions of the spacecraft were observable from AMOS. A detailed periodic analysis of the VisIm photometric signatures acquired on 2006 day-of-year (DOY) 028, 031 and 034 indicates a spin axis orientation consistent with that reported in the last telemetry down-linked from the satellite approximately seven weeks earlier. However, the periodic variations indicate a satellite spin rate of 0.4741 ° 0.0005 rpm, measurably slower than the last known spin rate from down-linked telemetry. Shortly after these initial AEOS observations were conducted, the NASA IMAGE satellite team up-linked commands to the spacecraft to increase the spin rate up to 0.52 rpm in order to test if the spacecraft could receive and execute such commands. Subsequent AMOS observations conducted 2006 DOY 150, however, did not show evidence of an increased spin rate, but instead indicated a further reduction down to 0.4709 ° 0.0004 rpm. The AEOS observations therefore confirm that the IMAGE spacecraft has lost the ability to receive and/or execute up-linked commands, and indicates that, between 2005-DEC-12 and 2006-MAY-30, the spacecraft's spin axis orientation remained stable to within detection limits but the spin rate declined at a rate of (3.1 ± 0.3) × 10-5 rpm/day, a deceleration most likely caused by magnetically-induced environmental torques.

Hall, D.; Africano, J.; Archambeault, D.; Birge, B.; Witte, D.; Kervin, P.

70

Monitoring Changes in Water Resources Systems Using High Resolution Satellite Observations: Application to Lake Urmia  

NASA Astrophysics Data System (ADS)

Lake Urmia with its unique ecosystem in northwestern Iran is the second largest saltwater lake in the world. It is home of more than 300 species of birds, reptiles, and mammals with high salinity level of more than 300 g/l. In recent years, a significant water retreat has occurred in this lake. In this study, we tried to monitor the desiccation of the lake over more than four decades using remote sensing observations. Multi-spectral high-resolution LandSat images of the Lake Urmia region from 1972 to 2012 were acquired to derive the lake area. The composite maps of the lake were created, and a Bayesian Maximum Likelihood classification technique was used to classify land and water in the composite maps. The time series of the lake area reveals that it has shrunk by more than 40% in the past ten years. Moreover, water budget related components such as precipitation, soil moisture, and drought indices from remote sensing of the lake basin were utilized to investigate if droughts or climate change are the primary driving forces behind this phenomenon. These analyses show that the retreat of the lake is not related to droughts or global climate change as it has survived several drought events before year 2000. Similar analyses conducted on Lake Van located about 400 km west of Lake Urmia with very similar climate pattern revealed no significant areal change despite the lake's exposure to similar drought events. These results raise serious concern about the destructive role of unbridled development coupled with supply-oriented water management scheme driven by a classic upstream-downstream competition for water in the Lake Urmia region. There is an urgent need to investigate sustainable restoration initiatives for Lake Urmia in order to prevent an environmental disaster comparable to catastrophic death of Aral Sea.

Norouzi, H.; AghaKouchak, A.; Madani, K.; Mirchi, A.; Farahmand, A.; Conway, C.

2013-12-01

71

Satellite Observations for Detecting and Tracking Changes in Atmospheric Composition  

EPA Science Inventory

The international scientific community's Integrated Global Atmosphere Chemistry Observation System report outlined a plan for ground-based, airborne and satellite Measurements, and models to integrate the observations into a 4-dimensional representation of the atmosphere (space a...

72

Earth and ocean dynamics satellites and systems  

NASA Technical Reports Server (NTRS)

An overview is presented of the present state of satellite and ground systems making observations of the dynamics of the solid earth and the oceans. Emphasis is placed on applications of space technology for practical use. Topics discussed include: satellite missions and results over the last two decades in the areas of earth gravity field, polar motions, earth tides, magnetic anomalies, and satellite-to-satellite tracking; laser ranging systems; development of the Very Long Baseline Interferometer; and Skylab radar altimeter data applications.

Vonbun, F. O.

1975-01-01

73

Thirty Years of Natural Satellites Mutual Events Observations  

Microsoft Academic Search

Phenomena in the Solar System have been observed for years: solar and lunar eclipses, occultations of stars by the Moon and the asteroids, eclipses of the satellites of Jupiter. Since 1973, mutual occultations and eclipses of the satellites of Jupiter, Saturn and Uranus were observed extensively during each opportunity i.e. the equinox on the planet: why? The study of the

Jean-eudes Arlot

2009-01-01

74

Applications systems verification and transfer project. Volume 4: Operational applications of satellite snow cover observations. Colorado Field Test Center  

NASA Technical Reports Server (NTRS)

The study was conducted on six watersheds ranging in size from 277 km to 3460 km in the Rio Grande and Arkansas River basins of southwestern Colorado. Six years of satellite data in the period 1973-78 were analyzed and snowcover maps prepared for all available image dates. Seven snowmapping techniques were explored; the photointerpretative method was selected as the most accurate. Three schemes to forecast snowmelt runoff employing satellite snowcover observations were investigated. They included a conceptual hydrologic model, a statistical model, and a graphical method. A reduction of 10% in the current average forecast error is estimated when snowcover data in snowmelt runoff forecasting is shown to be extremely promising. Inability to obtain repetitive coverage due to the 18 day cycle of LANDSAT, the occurrence of cloud cover and slow image delivery are obstacles to the immediate implementation of satellite derived snowcover in operational streamflow forecasting programs.

Shafer, B. A.; Leaf, C. F.; Danielson, J. A.; Moravec, G. F.

1981-01-01

75

Satellite video security systems  

NASA Astrophysics Data System (ADS)

During the last few years, satellites have been increasingly used to carry commercial free television programs, paid for by the viewers, as well as business and medical conferences. As a result, there is a large and growing need for video security systems to prevent both freeloading and eavesdropping. An ideal satellite security system would accept standard video and audio and convert them into totally random noise with no discernable information content. At the receive end, this noise would be converted back to video and audio identical to what went in. An investigation is conducted regarding the possibility to reproduce the features of the ideal system by means of a practically feasible system. It is pointed out that an extremely high degree of security can be achieved by digitizing signals, then applying an encryption algorithm. If done properly, the scrambled signal is almost random and the system is almost impossible to break.

Pennypacker, F. C.

76

Earth Observation Satellites and Chinese Applications  

NASA Astrophysics Data System (ADS)

In this talk existing and future Earth observation satellites are briefly described These satellites include meteorological satellites ocean satellites land resources satellites cartographic satellites and gravimetric satellites The Chinese government has paid and will pay more attention to and put more effort into enhancing Chinese earth observation satellite programs in the next fifteen years The utilization of these satellites will effectively help human beings to solve problems it faces in areas such as population natural resources and environment and natural hazards The author will emphasize the originality of the scientific and application aspects of the Chinese program in the field of Earth observations The main applications include early warning and prevention of forest fires flooding and drought disaster water and ocean ice disasters monitoring of landslides and urban subsidence investigation of land cover change and urban expansion as well as urban and rural planning The author introduces the most up-to-date technology used by Chinese scientists including fusion and integration of multi-sensor multi-platform optical and SAR data of remote sensing Most applications in China have obtained much support from related international organizations and universities around the world These applications in China are helpful for economic construction and the efficient improvement of living quality

Li, D.

77

Canada's satellite system  

NASA Astrophysics Data System (ADS)

The history of Canadian telecommunications satellite activities is traced. Most projects have been under the guidance of the government agency Telesat, which provides an interface to commercial operations. Canadian telecommunications satellites to-date have included Alouette 1 and 2 (1962, 1965), Isis 1 and 2 (1969, 1971), and Anik A1, A2 and A3 (1972, 1973, 1975) spacecraft. Domestic satellite telecommunications were initiated with the Anik series spacecraft. The Hermes spacecraft provided a platform for 14/12 GHz experiments and was followed by Anik B, with much the same capabilities. Canadian television broadcasts are now mainly handled by the Anik C series. The Anik D series is a testbed for voice/data communications. In order to democratize the system, Telesat permits access by any entity capable of operating uplink facilities.

Jedicke, P.; Cunningham, C.

1985-08-01

78

Satellites: A systems comparison  

NASA Technical Reports Server (NTRS)

The advantages of using geostationary platforms as a means of accommodating future missions and payloads in lieu of individual, smaller satellites are reviewed. The cost effectiveness of large capacity communications platforms with separate smaller satellites on a systems basis considering total costs to the end user is assessed. For two specific systems: a system to provide communications for U.S. domestic applications and a system to serve the Atlantic INTELSAT requirements. These simple platform applications were selected because they minimize associated institutional problems. Although they do not exploit the full advantages that can ultimately be obtained from large platforms with multidiscipline missions, to the extent that these simple platforms demonstrate cost benefits, such benefits can be further enhanced by the addition of other payloads to the platforms.

1978-01-01

79

Atmospheric density calibration using satellite drag observations  

Microsoft Academic Search

Thermospheric density models are currently the main source of error in the orbit determination and prediction of low Earth satellites. The empirical models which are in wide use today show an RMS accuracy of no better than 15 to 30 percent. This inherent accuracy barrier can be overcome when adjusting several correction parameters using concurrent observations of satellite drag. We

E. Doornbos; H. Klinkrad; P. Visser

2004-01-01

80

The Indian National Satellite System - Insat  

NASA Astrophysics Data System (ADS)

Insat is a multiagency multipurpose operational satellite system for domestic long-distance telecommunications, meteorological earth observation and data relay, direct satellite TV broadcasting, and radio and TV program distribution for rebroadcasting through terrestrial transmitters. The first-generation system currently in operation is described as well as plans for a second-generation Insat-II system. The Insat-II system offers greater immunity against single launch/satellite catastrophies.

Rao, U. R.; Pant, N.; Kale, P. P.; Narayanan, K.; Ramachandran, P.

1987-11-01

81

Satellite Navigation Systems  

NSDL National Science Digital Library

The Global Positioning System (GPS) has been in operation for several years, and its use is continually rising. GPS is the main satellite navigation system developed by the United States. There are countless applications of this technology, and numerous international efforts are currently underway.The Topcon Positioning Systems company provides an excellent introduction to GPS technology in its online book (1). The first couple chapters describe the evolution of GPS and its fundamentals, and the remaining material focuses on some specific issues. A more advanced tutorial is given through the IBM Web site (2). A brief, free registration is required to view it, and some familiarity with Java is recommended. The European Space Agency provides this page about satellite navigation (3), which describes, among other things, Galileo. This is not the astronomer; Galileo is Europe's version of GPS, scheduled for completion in 2008. Another system, developed by Russia, is detailed on the Space and Technology Web site (4). The short summary describes the 20-year history of the Global Navigation Satellite System (GLONASS), as well as upgrades that are in progress. Differential GPS, a service that is more accurate than standard GPS in areas with poor coverage, is operated by the US Coast Guard Navigation Center (5). Some information about the status of nationwide DGPS expansion is given. Several research and development projects, technology highlights, and GPS implementations are covered on the UNAVCO home page (6). The facility primarily fosters work to expand the applications of satellite navigation. With the wave of kidnapping cases reported across the country, a novel use of GPS is being marketed to keep track of children (7). These portable devices can be worn on the wrist, like a watch, so parents can always know where their kids are. Another news story describes the use of GPS in mining operations (8). The technology allows operators of huge three-story dump trucks to detect obstacles and maneuver the vehicle with only limited visibility.

Leske, Cavin.

2002-01-01

82

Laser satellite power systems  

SciTech Connect

A laser satellite power system (SPS) converts solar power captured by earth-orbiting satellites into electrical power on the earth's surface, the satellite-to-ground transmission of power being effected by laser beam. The laser SPS may be an alternative to the microwave SPS. Microwaves easily penetrate clouds while laser radiation does not. Although there is this major disadvantage to a laser SPS, that system has four important advantages over the microwave alternative: (1) land requirements are much less, (2) radiation levels are low outside the laser ground stations, (3) laser beam sidelobes are not expected to interfere with electromagnetic systems, and (4) the laser system lends itself to small-scale demonstration. After describing lasers and how they work, the report discusses the five lasers that are candidates for application in a laser SPS: electric discharge lasers, direct and indirect solar pumped lasers, free electron lasers, and closed-cycle chemical lasers. The Lockheed laser SPS is examined in some detail. To determine whether a laser SPS will be worthy of future deployment, its capabilities need to be better understood and its attractiveness relative to other electric power options better assessed. First priority should be given to potential program stoppers, e.g., beam attenuation by clouds. If investigation shows these potential program stoppers to be resolvable, further research should investigate lasers that are particularly promising for SPS application.

Walbridge, E.W.

1980-01-01

83

NPP: Why Another Earth-Observing Satellite?  

NASA Video Gallery

NPP will soon be NASA's newest Earth-observing satellite. To showcase how NPP will be used for both understanding the health of our planet now -- as well as how things might change in the future --...

84

Global Warming: Evidence from Satellite Observations.  

National Technical Information Service (NTIS)

Observations made in Channel 2 (53.74 GHz) of the Microwave Sounding Unit (MSU) radiometer, flown onboard sequential, sun-synchronous, polar-orbiting NOAA (National Oceanic and Atmospheric Administration) operational satellites, indicate that the mean tem...

C. Prabhakara R. Iacovazzi J. M. Yoo G. Dalu

2000-01-01

85

Magnetopause structure from satellite observations  

NASA Technical Reports Server (NTRS)

Observations on magnetopause structure are reported. Major topics covered include: classical reconnection, transport mechanisms, magnetospheric boundary layers, tearing modes, and Jupiter's magnetopause.

Sonnerup, B. U. O.

1979-01-01

86

Techniques for computing regional radiant emittances of the earth-atmosphere system from observations by wide-angle satellite radiometers, phase 3  

NASA Technical Reports Server (NTRS)

Radiometers on earth orbiting satellites measure the exchange of radiant energy between the earth-atmosphere (E-A) system and space at observation points in space external to the E-A system. Observations by wideangle, spherical and flat radiometers are analyzed and interpreted with regard to the general problem of the earth energy budget (EEB) and to the problem of determining the energy budget of regions smaller than the field of view (FOV) of these radiometers.

Pina, J. F.; House, F. B.

1975-01-01

87

Impacts of geostationary satellite measurements on CO forecasting: An observing system simulation experiment with GEOS-Chem/LETKF data assimilation system  

NASA Astrophysics Data System (ADS)

We developed a chemical data assimilation system based on the GEOS-Chem global chemical transport model (CTM) and an ensemble-based data assimilation method, and performed an observing system simulation experiment (OSSE) to evaluate the impact of geostationary (GEO) satellite data obtained with a multi-spectral (thermal infrared (TIR) and near infrared (NIR)) sensor on air quality forecasting in East Asia. Initial conditions determined by assimilation of the three observation sets improved the forecasting of trans-boundary CO outflow. The performance of GEO satellite with TIR sensor (GEO-TIR) was better than that of LEO satellite with TIR sensor (LEO-TIR). However, in Seoul district (the Korean Peninsula) and Northern Kyushu (western Japan), the positive impact of the wider coverage and higher frequency of GEO disappeared when the forecast time was longer than 48 h. GEO satellite with NIR and TIR sensor (GEO-NIR + TIR) improved the forecast most, reducing the root mean square difference (RMSD), normalized mean bias, and normalized mean difference by more than 20% even for a forecast time longer than 48 h. Using the LEO-TIR result as a benchmark, we evaluated the ability of GEO-NIR + TIR to improve the forecast. The 60-h CO forecasting performances of GEO-TIR and GEO-NIR + TIR were about 30% and 120% better, respectively, than that of LEO-TIR. The wider coverage and higher frequency of GEO therefore improved the RMSD by 30%, and the higher sensitivity in the lower troposphere of NIR + TIR improved it by an additional 90%. Thus, the higher sensitivity in the lower troposphere of NIR + TIR as well as the wider coverage and higher frequency of GEO had a notably positive impact on the forecasting of trans-boundary pollutants over East Asia.

Yumimoto, Keiya

2013-08-01

88

Simulations of satellite Doppler wind observations  

NASA Technical Reports Server (NTRS)

This study will involve two objectives: (1) to develop, through computer simulations, optimal satellite-based sensor scanning techniques for direct measurement of tropospheric winds on the meso- and synoptic scales; and (2) to construct simulations of remotely measured wind fields for assessing impact of such fields on the diagnosis and prognosis of atmospheric phenomena through the use of Observing System Simulation Experiments (OSSE). Using the LAWS Simulation Model (LSM), various global coverage scenarios have been investigated as part of an effort to define the optimal orbit, configuration and sampling strategies for observations of winds for use in global circulation models. Simulated data sets have been provided to GSFC, FSU and several LAWS team members. Particular emphasis has been on providing realistic cloud cover, cirrus backscatter, aerosol distribution and wind variance on scales less than 600 km. Progress is currently being made to incorporate other remote sensors (AIRS/AMSU, STIKSCAT) into the global OSSEs.

Emmitt, George D.; Wood, S. A.; Wood, L. S.; Vaughan, O.

1993-01-01

89

Question No. 5: What Role Can Satellites Take, as a Complement to Ground Based Measurement Systems, to Provide Sustained Observations to Monitor GHG Emissions?  

NASA Technical Reports Server (NTRS)

What role can satellites take, as a complement to ground based measurement systems, to provide sustained observations to monitor GHG emissions (e.g., CO2, CH4, O3, N2O, CFC s, NH3, and NF3) that contribute to global warming?

Chahine, Moustafa; Olsen, Edward

2011-01-01

90

ASTER satellite observations for international disaster management  

USGS Publications Warehouse

When lives are threatened or lost due to catastrophic disasters, and when massive financial impacts are experienced, international emergency response teams rapidly mobilize to provide urgently required support. Satellite observations of affected areas often provide essential insight into the magnitude and details of the impacts. The large cost and high complexity of developing and operating satellite flight and ground systems encourages international collaboration in acquiring imagery for such significant global events in order to speed delivery of critical information to help those affected, and optimize spectral, spatial, and temporal coverage of the areas of interest. The International Charter-Space and Major Disasters was established to enable such collaboration in sensor tasking during times of crisis and is often activated in response to calls for assistance from authorized users. Insight is provided from a U.S. perspective into sensor support for Charter activations and other disaster events through a description of the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER), which has been used to support emergency situations for over a decade through its expedited tasking and near real-time data delivery capabilities. Examples of successes achieved and challenges encountered in international collaboration to develop related systems and fulfill tasking requests suggest operational considerations for new missions as well as areas for future enhancements.

Duda, K. A.; Abrams, M.

2012-01-01

91

Comparison of Surface Ground Temperature from Satellite Observations and the Off-Line Land Surface GEOS Assimilation System  

NASA Technical Reports Server (NTRS)

The surface ground temperature (Tg) is an important meteorological variable, because it represents an integrated thermal state of the land surface determined by a complex surface energy budget. Furthermore, Tg affects both the surface sensible and latent heat fluxes. Through these fluxes. the surface budget is coupled with the atmosphere above. Accurate Tg data are useful for estimating the surface radiation budget and fluxes, as well as soil moisture. Tg is not included in conventional synoptical weather station reports. Currently, satellites provide Tg estimates globally. It is necessary to carefully consider appropriate methods of using these satellite data in a data assimilation system. Recently, an Off-line Land surface GEOS Assimilation (OLGA) system was implemented at the Data Assimilation Office at NASA-GSFC. One of the goals of OLGA is to assimilate satellite-derived Tg data. Prior to the Tg assimilation, a thorough investigation of satellite- and model-derived Tg, including error estimates, is required. In this study we examine the Tg from the n Project (ISCCP DI) data and the OLGA simulations. The ISCCP data used here are 3-hourly DI data (2.5x2.5 degree resolution) for 1992 summer months (June, July, and August) and winter months (January and February). The model Tg for the same periods were generated by OLGA. The forcing data for this OLGA 1992 simulation were generated from the GEOS-1 Data Assimilation System (DAS) at Data Assimilation Office NASA-GSFC. We examine the discrepancies between ISCCP and OLGA Tg with a focus on its spatial and temporal characteristics, particularly on the diurnal cycle. The error statistics in both data sets, including bias, will be estimated. The impact of surface properties, including vegetation cover and type, topography, etc, on the discrepancies will be addressed.

Yang, R.; Houser, P.; Joiner, J.

1998-01-01

92

Severe storms observing satellite study  

NASA Technical Reports Server (NTRS)

Payload distribution and the attitude control system for the multi-mission modular spacecraft/StormSat configuration are discussed. The design of the advanced atmospheric sounder and imaging radiometer (AASIR) gimbal drive and its servomechanism is described. Onboard data handling, data downlink communications, and ground data handling systems are developed. Additional topics covered include: magnetic unloading at synchronous altitude, north-south stationkeeping, and the feasibility and impact of flying the microwave atmospheric sounding radiometer (MASR) as an additional payload.

Iwens, R. P.; Stern, D. A.

1976-01-01

93

Lightning-Generated Whistler Waves Observed by Probes On The Communication/Navigation Outage Forecast System Satellite at Low Latitudes  

NASA Technical Reports Server (NTRS)

Direct evidence is presented for a causal relationship between lightning and strong electric field transients inside equatorial ionospheric density depletions. In fact, these whistler mode plasma waves may be the dominant electric field signal within such depletions. Optical lightning data from the Communication/Navigation Outage Forecast System (C/NOFS) satellite and global lightning location information from the World Wide Lightning Location Network are presented as independent verification that these electric field transients are caused by lightning. The electric field instrument on C/NOFS routinely measures lightning ]related electric field wave packets or sferics, associated with simultaneous measurements of optical flashes at all altitudes encountered by the satellite (401.867 km). Lightning ]generated whistler waves have abundant access to the topside ionosphere, even close to the magnetic equator.

Holzworth, R. H.; McCarthy, M. P.; Pfaff, R. F.; Jacobson, A. R.; Willcockson, W. L.; Rowland, D. E.

2011-01-01

94

Detection of subsurface eddies from satellite observations  

NASA Astrophysics Data System (ADS)

This study aims to develop an index that allows distinguishing between surface and subsurface intensified eddies from surface data only, in particular using the sea surface height and the sea surface temperature available from satellite observations. To do this, we propose the use of a simple index based on the ratio of the sea surface temperature anomaly (SSTa) and the sea level anomaly (SLA). This index is first derived using an academic approach, based on idealized assumptions of geostrophic balance and Gaussian-shaped vortices. This index depends on the vertical extent (or decreasing rate) of the eddy and because of its sensitivity to the exact shape of the vortex, we were not able to evaluate these depths from the surface fields and our results remain qualitative. Then, in order to examine the pertinence and validity of the proposed index, SSTa and SLA were computed using outputs of a realistic regional circulation model in the Peru-Chile upwelling system where both surface and subsurface eddies coexist. Over a seven year simulation, the statistics shows that 71% of eddies are correctly identified as surface or subsurface intensified. Multi-core eddies are also largely present and represent an average of 37% of all vortices. These multi-core eddies contribute to a large number of the wrong identification (15%). Finally, the index was successfully applied on in-situ data to detect a previously observed subsurface-intensified Swoddy (slope water eddy) in the Bay of Biscay. This study suggests that the index can be successfully used to determine the exact nature of mesoscale eddies (surface or subsurface- intensified) from satellite observations only.

Assassi, Charefeddine; Morel, Yves; Chaigneau, Alexis; Pegliasco, Cori; Vandermeirsch, Frederic; Rosemary, Morrow; Colas, François; Fleury, Sara; Cambra, Rémi

2014-05-01

95

Surface albedo based on geostationary satellite observations  

NASA Astrophysics Data System (ADS)

Surface albedo is the fraction of incoming solar radiation reflected by the land surface, and therefore is a sensitive indicator of environmental changes. To this end, surface albedo is identified as an Essential Climate Variable (ECV) by the Global Climate Observing System (GCOS). NOAA's National Climatic Data Center (NCDC) is implementing the Geostationary Surface Albedo (GSA; Lattanzio and Govaerts, 2010) algorithm for GOES data in support of an activity of the Sustained, Coordinated Processing of Environmental Satellite Data for Climate Monitoring (SCOPE-CM). SCOPE-CM helps coordinate ECV production responding to GCOS, WMO, and CEOS goals. The GSA algorithm was developed jointly by EUMETSAT and Joint Research Centre (JRC) using a method proposed by Pinty et al. (2000) to retrieve surface albedo by processing day-time, cloud-free geostationary observations from a single visible band. Currently, the GSA algorithm generates products operationally at EUMETSAT using geostationary data from satellites at 0° and 63°E and at JMA using 140°E geostationary data. To support development of an aggregate global albedo product, NCDC will apply the GSA algorithm to data from GOES-E (75°W) and GOES-W (135°W). For the GOES implementation, raw GOES observations are calibrated against AVHRR reflectance data available in PATMOS-x. Surface angular anisotropy is then determined through the inversion of the GSA radiative transfer model using multiple geostationary images collected over a day under different illumination conditions. The inversion process additionally requires ancillary total column ozone and water vapor values, which for the GOES implementation are acquired from the 20th Century Reanalysis V2 data set provided by the NOAA/OAR/ESRL PSD. The GSA algorithm produces a 10-day composite surface albedo map. This product will initially be developed for the period 2000-2003. Later, it will be applied to the complete GOES data collection (1978-present) as part of NOAA's Climate Data Record Program.

Matthews, J. L.; Lattanzio, A.; Hankins, B.; Inamdar, A.; Knapp, K.; Privette, J. L.

2011-12-01

96

Satellite systems for marine rescue  

NASA Astrophysics Data System (ADS)

Existing and proposed maritime communication satellite systems are briefly reviewed. In particular, the INMARSAT system and an international project to develop a search and rescue network are discussed.

Konovalov, B.

1982-08-01

97

Satellite systems for marine rescue  

Microsoft Academic Search

Existing and proposed maritime communication satellite systems are briefly reviewed. In particular, the INMARSAT system and an international project to develop a search and rescue network are discussed.

B. Konovalov

1982-01-01

98

First optical observations of artificial Earth's satellites  

NASA Astrophysics Data System (ADS)

A review of the first optical observations of the artificial satellites in the USSR as well as in former communist countries (DDR, Romania,Poland) is given. The role by Alla G. Masevich, I.D. Zhongolovich and Yu.V. Batrakov is underlined in the organization of observations.

Rykhlova, L. V.

2008-08-01

99

The AMSC mobile satellite system  

NASA Technical Reports Server (NTRS)

The American Mobile Satellite Consortium (AMSC) Mobile Satellite Service (MSS) system is described. AMSC will use three multi-beam satellites to provide L-band MSS coverage to the United States, Canada and Mexico. The AMSC MSS system will have several noteworthy features, including a priority assignment processor that will ensure preemptive access to emergency services, a flexible SCPC channel scheme that will support a wide diversity of services, enlarged system capacity through frequency and orbit reuse, and high effective satellite transmitted power. Each AMSC satellite will make use of 14 MHz (bi-directional) of L-band spectrum. The Ku-band will be used for feeder links.

Agnew, Carson E.; Bhagat, Jai; Hopper, Edwin A.; Kiesling, John D.; Exner, Michael L.; Melillo, Lawrence; Noreen, Gary K.; Parrott, Billy J.

1988-01-01

100

Present Status of the Satellite Observation Station Wettzell Zur Bisherigen Bilanz der Satellitenbeobachtungsstation Wettzell.  

National Technical Information Service (NTIS)

The observation station for satellite geodesy in the Bavarian Forest (Germany) is described. Its observation equipment includes a laser ranging system (Neodymium-yag laser), a VHF Doppler system for reception of frequencies of the Navy Navigation Satellit...

H. Seeger P. Wilson K. Nottarp D. Lelgemann

1976-01-01

101

Thirty Years of Natural Satellites Mutual Events Observations  

NASA Astrophysics Data System (ADS)

Phenomena in the Solar System have been observed for years: solar and lunar eclipses, occultations of stars by the Moon and the asteroids, eclipses of the satellites of Jupiter. Since 1973, mutual occultations and eclipses of the satellites of Jupiter, Saturn and Uranus were observed extensively during each opportunity i.e. the equinox on the planet: why? The study of the systems of natural satellites needs to explore the dynamics of these objects: each small dynamical effect is the signature of some physical property. In order to validate the theoretical models, very accurate observations are needed. Most of the direct astrometric observations have their accuracy limited by the diffraction of the light in the telescope and by the star catalogues used for calibration. Phenomena have not this limitation: the accuracy is not in angle but in kilometres in space. Since, the observed satellites have no atmosphere, these photometric events are easy to analyse providing relative positions accurate to a few kilometres corresponding to a few mas in geocentric angle. More, during an occultation, the surface of the satellites may be studied: volcanoes of Io (positions and fluxes) were observed that way. Mutual events observations together with the best observations made since several decades allowed improving dynamical models of the satellites systems of Jupiter, Saturn and Uranus. Concerning Io, the dissipation of energy in its internal structure by the Jovian tides has been made into evidence thanks to fitting the models on accurate observations including mutual events. Eight observational campaigns were organized for the Jovian satellites, three for the Saturnians and one for the Uranians providing more than 1400 light curves (see the data base at http://www.imcce.fr/fr/ephemerides/generateur/saimirror/obsindhe.htm ). The author acknowledges the numerous observers worldwide who provide the observations, the observatories permitting observations and the French CNRS who supported these campaigns.

Arlot, Jean-eudes; Events Observers, Mutual

2009-09-01

102

New observations of Saturn's coorbital satellites  

NASA Technical Reports Server (NTRS)

The strong planetary methane and hydrogen absorption at 2.0-2.4 microns are exploited in the present observations of the Saturnian coorbital satellites Janus and Epimetheus as they passed over the north pole of Saturn at superior conjunction. These observations confirm the orbital model results of Yoder at al. (1989), especially in the question as to the low density of both satellites; in addition, a much stronger solution is furnished which is essentially independent of 1966 data for Epimethius. The low density results are interpreted as indicative that the objects are composed of relatively pure water ice, but with porosities of the order of 30 percent.

Nicholson, Philip D.; Hamilton, Douglas P.; Matthews, Keith; Yoder, Charles F.

1992-01-01

103

Earth System: Satellites  

NSDL National Science Digital Library

There are thousands of artificial satellites circling our planet for navigation, communications, entertainment, and science. These satellites are an integral part of our everyday life, and they collect data which cannot be obtained from Earth's surface. This video segment describes the basic components of a satellite and some of applications that have been developed for both geostationary and orbiting satellites. The segment is three minutes fifty seconds in length. A background essay and discussion questions are included.

104

Mobile satellite broadcast system design  

Microsoft Academic Search

An innovative mobile satellite network that will broadcast data and audio signals (voice and music) to mobiles throughout the contiguous United States through MSAT, a North American mobile satellite system now under construction, is described. Mobiles with suitably equipped radios and small L-band omnidirectional mobile satellite antennas simultaneously receive one data channel and any one of many audio channels. Pages,

Gary K. Noreen

1990-01-01

105

Applications of Satellite Observations to Aerosol Analyses and Forecasting using the NAAPS Model and the DataFed Distributed Data System  

NASA Astrophysics Data System (ADS)

Near-real-time (NRT) aerosol characterization, forecasting and decision support is now possible through the availability of (1) surface-based monitoring of regional PM concentrations, (2) global-scale columnar aerosol observations through satellites; (3) an aerosol model (NAAPS) that is capable of assimilating NRT satellite observations; and (4) an emerging cyber infrastructure for processing and distribution of data and model results (DataFed) for a wide range of users. This report describes the evolving NRT aerosol analysis and forecasting system and its applications at Federal and State and other AQ Agencies and groups. Through use cases and persistent real-world applications in the US and abroad, the report will show how satellite observations along with surface data and models are combined to aid decision support for AQ management, science and informing the public. NAAPS is the U.S. Navy's global aerosol and visibility forecast model that generates operational six-day global-scale forecasts for sulfate, dust, sea salt, and smoke aerosol. Through NAVDAS-AOD, NAAPS operationally assimilates filtered and corrected MODIS MOD04 aerosol optical depths and uses satellite-derived FLAMBÉ smoke emissions. Washington University's federated data system, DataFed, consist of a (1) data server which mediates the access to AQ datasets from distributed providers (NASA, NOAA, EPA, etc.,); (2) an AQ Data Catalog for finding and accessing data; and (3) a set of application programs/tools for browsing, exploring, comparing, aggregating, fusing data, evaluating models and delivering outputs through interactive visualization. NAAPS and DataFed are components of the Global Earth Observation System of Systems (GEOSS). Satellite data support the detection of long-range transported wind-blown dust and biomass smoke aerosols on hemispheric scales. The AQ management and analyst communities use the satellite/model data through DataFed and other channels as evidence for Exceptional Events (EE) as defined by EPA; i.e., Sahara dust impact on Texas and Florida, local dusts events in the Southwestern U.S. and Canadian smoke events over the Northeastern U.S. Recent applications include the impact analysis of a major Saudi Arabian dust event on Mumbai, India air quality. The NAAPS model and the DataFed tools can visualize the dynamic AQ events as they are manifested through the different sensors. Satellite-derived aerosol observations assimilated into NAAPS provide estimates of daily emission rates for dust and biomass fire sources. Tuning and reconciliation of the observations, emissions and models constitutes a key and novel contribution yielding a convergence toward the true five-dimensional (X, Y, Z, T, Composition) characterization of the atmospheric aerosol data space. This observation-emission-model reconciliation effort is aided by model evaluation tools and supports the international HTAP program. The report will also discuss some of the challenges facing multi-disciplinary, multi-agency, multi-national applications of integrated observation-modeling system of systems that impede the incorporation of satellite observations into AQ management decision support systems.

Husar, R. B.; Hoijarvi, K.; Westphal, D. L.; Scheffe, R.; Keating, T.; Frank, N.; Poirot, R.; DuBois, D. W.; Bleiweiss, M. P.; Eberhard, W. L.; Menon, R.; Sethi, V.; Deshpande, A.

2012-12-01

106

Comparison of filter predictions with satellite observations  

SciTech Connect

Satellite observations of meteor entry are used to calibrate a filter model of fragmentation. Predicted sizes and masses compare favorably with data and analytic interpretations for objects of all sizes. However, objects that fragment into many large objects should be treated by the decomposition of the radiation signal into the contributions from the different fragments.

Canavan, G.H.

1997-10-01

107

Satellite Observation of Atmospheric Nuclear Gamma Radiation.  

National Technical Information Service (NTIS)

A satellite observation of the spectrum of gamma radiation from the Earth's atmosphere is presented in the energy interval from 300 keV to 8.5 MeV. The data were accumulated by the Gamma Ray Spectrometer on the Solar Maximum Mission over three and one-hal...

J. R. Letaw G. H. Share R. L. Kinzer R. Silberberg C. H. Tsao

1987-01-01

108

Scheduling Earth Observing Satellites with Evolutionary Algorithms  

Microsoft Academic Search

I. ABSTRACT We hypothesize that evolutionary algorithms can effectively schedule coordinated fleets of Earth observing satellites. The constraints are complex and the bottlenecks are not well un- derstood, a condition where evolutionary algorithms are often effective. This is, in part, because evolutionary algorithms require only that one can represent solutions, modify solutions, and evaluate solution fitness. To test the hypothesis

Al Globus; James Crawford; Jason Lohn; Anna Pryor

2003-01-01

109

Gravity gradiometry from the Tethered Satellite System  

Microsoft Academic Search

Measurement of the gradient of the gravitational acceleration from a satellite platform is likely to provide the next improvement in knowledge of the earth's gravity field after the upcoming Geopotential Research Mission (GRM). Observations from the subsatellite of a Tethered Satellite System (TSS) would increase sensitivity and resolution due to the low altitude possible. However, the TSS is a dynamically

G. E. Gullahorn; M. D. Grossi; F. Fuligni

1985-01-01

110

Gravity Gradiometry from the Tethered Satellite System  

Microsoft Academic Search

Measurement of the gradient of the gravitational acceleration from a satellite platform is likely to provide the next improvement in knowledge of the Earth's gravity field after the upcoming Geopotential Research Mission (GRM). Observations from the subsatellite of a Tethered Satellite System (TSS) would increase sensitivity and resolution due to the low altitude possible. However, the TSS is a dynamically

Gordon Gullahorn; Franco Fuligni; Mario Grossi

1985-01-01

111

CCD astrometric observations of Uranian satellites.  

NASA Astrophysics Data System (ADS)

Astrometric positions of the five largest satellites are given for the oppositions of Uranus for the years 1989 to 1994. These positions were measured on 368 CCD frames obtained at the Cassegrain focus of a 1.6-m reflector. They are compared with the theoretically calculated positions from GUST86 (Laskar & Jacobson 1987). The observed minus calculated residuals referred to Oberon have standard deviations of the order of 0."05 for the three greatest Uranian satellites and 0.07" for Miranda. These residuals are comparable to the best available in the literature.

Veiga, C. H.; Vieira Martins, R.

1995-11-01

112

Seasonal streamflow estimation employing satellite snowcover observations  

NASA Technical Reports Server (NTRS)

Low resolution meteorological satellite and high resolution earth resources satellite data have been used to map snow covered area over the upper Indus River and the Wind River Mountains of Wyoming, respectively. For the Indus River early spring snow covered area was extracted and related to April through June stream flow from 1967-1971 using a regression equation. Prediction of the April-June 1972 stream flow from the satellite data was within three percent of the actual total. Composited results from two years of data over seven Wind River Mountain watersheds indicated that LANDSAT-1 snow cover observations, separated on the basis of watershed elevation, could also be related to runoff in significant regression equations.

Rango, A.; Salomonson, V. V.; Foster, J. L.

1975-01-01

113

Satellite observations of an ionospheric acceleration mechanism  

Microsoft Academic Search

A satellite-borne energetic ion mass spectrometer experiment has detected fluxes of O\\/sup +\\/ and H\\/sup +\\/ ions flowing up out of the ionosphere in the auroral and polar regions. The observed ions have energies in the keV range, narrow pitch-angle distributions aligned along the magnetic field direction and peak flux intensities of the order of 10⁸ (cm²-sec-sterad-keV)⁻¹. The observations were

E. G. Shelley; R. D. Sharp; R. G. Johnson

1976-01-01

114

Satellite systems for maritime navigation  

NASA Astrophysics Data System (ADS)

The principles underlying the design of Doppler satellite navigation systems are examined, and the characteristics of existing and proposed satellite systems for maritime navigation are described. Particular attention is given to the COSPAS-SARSAT system, GPS/Navstar, and the Navsat, Granas, and Geostar projects. The features of shipboard navigation instruments are examined.

Bogdanov, Valerii Anatol'evich; Sorochinskii, Valentin Alekseevich; Iakshevich, Evgenii Viktorovich

115

A CCD photometric camera for satellite observation  

NASA Astrophysics Data System (ADS)

A CCD camera for photometric measurement of satellites has been built, tested, and has been integrated into the Experimental Test System (ETS). This report describes the camera, the computer system and programs used to collect data, the camera's sensitivity parameters, the sensitivity of the camera on the ETS 31-inch Telescope, and its projected sensitivity on Ground-Based Electro-Optical Deep Space Surveillance System (GEODSS) main telescope.

Mayer, G. J.; MacDonald, M. J.; Pong, N. G. S.

1983-11-01

116

Land mobile satellite demonstration system  

NASA Technical Reports Server (NTRS)

A land mobile satellite demonstration system is described. It ulilizes the INMARSAT MARECS B2 satellite at 26 degrees W. The system provides data transmission using a poll-response protocol with error detection and retransmission at 200 b/s rate. For most tests a 1.8 inch monopole antenna was used, along with a satellite EIRP normally used for four voice channels. A brief summary of the results are given and the overall system consisting of three elements in addition to the satellite (the mobile unit, the base station, and the office terminal and map display) is described. Throughput statistics from one trip are summarized.

Gooch, Guy M.; Nicholas, David C.

1988-01-01

117

Astrometric observations of planetary satellites at the Abastumani Astrophysical Observatory  

NASA Astrophysics Data System (ADS)

We present and discuss the results of the astrometry project during which we observed the satellites of Mars, Jupiter, Saturn, Uranus, and Neptune at the Abastumani Astrophysical Observatory (Georgia) between 1983 and 1994. Observations at the Abastumani Observatory were performed with the double Zeiss astrograph (DZA: D/ F = 400/3024 mm) and AZT-11 telescope ( F = 16 m). We processed a large array of observations and determined exact coordinates of the planets and their satellites in a system of reference stars of modern catalogues as well as relative coordinates of the satellites. The results were compared with modern ephemerides using the MULTI-SAT software. The comparison enabled us to estimate the accuracy of observations (their random and systematic uncertainties) and the accuracy of modern theories of the motion of planets and their satellites. Random uncertainties of observations are estimated to be 0.10?-0.40? for various objects and observational conditions. Observational results obtained for Uranus, Neptune and the satellites Titania and Oberon were shown to deviate appreciably and systematically from theories of their motion. The results of observations are presented in the Pulkovo database for Solar System bodies that is available at the website http://www.puldb.ru.

Kiseleva, T. P.; Chanturiya, S. M.; Vasil'eva, T. A.; Kalinichenko, O. A.

2012-11-01

118

Globally Gridded Satellite observations for climate studies  

USGS Publications Warehouse

Geostationary satellites have provided routine, high temporal resolution Earth observations since the 1970s. Despite the long period of record, use of these data in climate studies has been limited for numerous reasons, among them that no central archive of geostationary data for all international satellites exists, full temporal and spatial resolution data are voluminous, and diverse calibration and navigation formats encumber the uniform processing needed for multisatellite climate studies. The International Satellite Cloud Climatology Project (ISCCP) set the stage for overcoming these issues by archiving a subset of the full-resolution geostationary data at ~10-km resolution at 3-hourly intervals since 1983. Recent efforts at NOAA's National Climatic Data Center to provide convenient access to these data include remapping the data to a standard map projection, recalibrating the data to optimize temporal homogeneity, extending the record of observations back to 1980, and reformatting the data for broad public distribution. The Gridded Satellite (GridSat) dataset includes observations from the visible, infrared window, and infrared water vapor channels. Data are stored in Network Common Data Format (netCDF) using standards that permit a wide variety of tools and libraries to process the data quickly and easily. A novel data layering approach, together with appropriate satellite and file metadata, allows users to access GridSat data at varying levels of complexity based on their needs. The result is a climate data record already in use by the meteorological community. Examples include reanalysis of tropical cyclones, studies of global precipitation, and detection and tracking of the intertropical convergence zone.

Knapp, K. R.; Ansari, S.; Bain, C. L.; Bourassa, M. A.; Dickinson, M. J.; Funk, C.; Helms, C. N.; Hennon, C. C.; Holmes, C. D.; Huffman, G. J.; Kossin, J. P.; Lee, H. -T.; Loew, A.; Magnusdottir, G.

2011-01-01

119

Coronal observations from the SMM satellite  

NASA Technical Reports Server (NTRS)

The scientific purpose, coronal observations, and the instrument design and control of the Coronagraph/Polarimeter aboard the Solar Maximum Mission (SMM) satellite are discussed. The instruments were made with an optical design using an achromatic objective lens providing a 10 arcsec resolution in imaging and an SEC vidicon detector allowing integration on the low light levels of the corona. The computer control assures flexibility in the observing program to optimize observations of changing solar phenomena and allows rapid response to SMM or ground-commanded solar flare alerts.

Csoeke-Poeckh, A.; Lee, R. H.; Wagner, W. J.; House, L. L.; Sawyer, C.; Hildner, E.

1981-01-01

120

Greenhouse Gases Observation from the GOSAT Satellite  

NASA Astrophysics Data System (ADS)

The Greenhouse gases Observing Satellite (GOSAT) is a satellite to monitor the carbon dioxide (CO2) and the methane (CH4) globally from orbit. The two instruments are accommodated on GOSAT. The Greenhouse gases Observing Sensor is a Fourier-Transform Spectrometer (FTS), which detects gas absorption spectra of the solar short wave infrared (SWIR) reflected on the earth_fs surface as well as of the thermal infrared (TIR) radiated from the ground and the atmosphere. The FTS is capable of detecting three narrow bands (0.76, 1.6, and 2 micron) and a wide band (5.5-14.3 micron) with 0.2 cm-1 spectral resolution. The cloud and aerosol sensor is an imager of ultraviolet (UV), visible, and SWIR to correct cloud and aerosol interference. The presentation includes the instrument design, pre-launch calibration and onboard calibration schemes; as well as, some test results using the Bread Board Model (BBM).

Kuze, A.; Kondo, K.; Kaneko, Y.; Hamazaki, T.

2005-12-01

121

Satellite Observations of Atmospheric Gravity Waves  

NASA Technical Reports Server (NTRS)

The Microwave Limb Sounder (MLS) on the Upper Atmosphere Research Satellite produced the first global maps of small-scale gravity wave variances in the middle atmosphere. Observations at 30-88 km altitudes show that the variances of 30-100 km horizontal scales are strongly correlated with surface topography and stratospheric jet streams. The several years of MLS data will provide a climatology of global gravity wave activity needed for modeling atmospheric circulations and mixing processes.

Wu, D. L.; Waters, J. W.

1995-01-01

122

Use of meteorological satellite observations in weather modification programs  

NASA Technical Reports Server (NTRS)

The potential value of weather satellite data in field operations of weather modification is appraised. It was found that satellites could play a useful role in operational weather modification projects, particularly in the recognition of treatment opportunities. Satellite cloud photographs and infrared observations appear promising in the identification of treatment opportunities in seeding orographic cloud systems for increased snowpack, in seeding convective clouds for increased rainfall, in identifying hail threats, and in tracking and observing hurricanes as an aid to timing and location of seeding treatments. It was concluded that the potential value of satellite data in the treatment and evaluation phases of operational projects is not as great as in the recognition of treatment opportunity.

Dennis, A. S.; Smith, P. L., Jr.; Biswas, K. R.

1973-01-01

123

Infrared observations of outer planet satellites  

NASA Astrophysics Data System (ADS)

This task supports IR observations of the outer planet satellites. These data provide vital information about the thermophysical properties of satellite surfaces, including internal heat sources for Io. Observations include both broad and narrow band measurementsin the 2 to 20 micrometer spectral range. The program in the last year has aimed at obtaining lonitude coverage on Io to establish stability of hot spot patterns previously reported. Several runs produced the most complete data set for an apparition since the start of the program. Unfortunately, bad weather limited coverage of key longitude ranges containing the largest known hot spot Loki. Among the preliminary results is the observation of an outburst in Io's thermal flux that was measured at 4.8, 8.7 and 20 micrometer. Analysis of the data has given the best evidence to date of silicate volcanism on Io; this is one of the most significant pieces of the puzzle as to the relative roles of silicate and sulfur volcanism on Io. Researchers are collaborating with J. Goguen (NRC RRA to finish reduction of mutual event data, which have already improved ephermeris information for the satellites. The data appear to place significant limits on the characteristics of any leading side hot spots.

Johnson, T. V.

1988-08-01

124

Infrared observations of outer planet satellites  

NASA Technical Reports Server (NTRS)

This task supports IR observations of the outer planet satellites. These data provide vital information about the thermophysical properties of satellite surfaces, including internal heat sources for Io. Observations include both broad and narrow band measurementsin the 2 to 20 micrometer spectral range. The program in the last year has aimed at obtaining lonitude coverage on Io to establish stability of hot spot patterns previously reported. Several runs produced the most complete data set for an apparition since the start of the program. Unfortunately, bad weather limited coverage of key longitude ranges containing the largest known hot spot Loki. Among the preliminary results is the observation of an outburst in Io's thermal flux that was measured at 4.8, 8.7 and 20 micrometer. Analysis of the data has given the best evidence to date of silicate volcanism on Io; this is one of the most significant pieces of the puzzle as to the relative roles of silicate and sulfur volcanism on Io. Researchers are collaborating with J. Goguen (NRC RRA to finish reduction of mutual event data, which have already improved ephermeris information for the satellites. The data appear to place significant limits on the characteristics of any leading side hot spots.

Johnson, T. V.

1988-01-01

125

Land Mobile Satellite Data System.  

National Technical Information Service (NTIS)

The Telesat Mobile Incorporated (TMI) Mobile Data System (MDS) was developed to apply satellite technology to the transportation industry's requirement for a fleet management system. It will provide two-way messaging and automatic position reporting capab...

J. D. B. Kent

1990-01-01

126

Weather satellites: Systems, data, and environmental applications  

Microsoft Academic Search

The present review of weather-satellite systems, data, and environmental applications encompasses the evolution of space-based weather observation, national observing capabilities, sensor data and processing, climate and meteorological applications, applications to land, agriculture, and ocean sciences, and some future directions. Specific issues addressed include U.S. operational polar and geostationary satellites, the Japanese GMS, remote sensing instrumentation, the Argos data collection and

P. K. Rao; S. J. Holmes; R. K. Anderson; J. S. Winston; P. E. Lehr

1990-01-01

127

NASA's Earth Observing System  

NSDL National Science Digital Library

NASA's Earth Observing System (EOS) is "a coordinated series of polar-orbiting and low inclination satellites for long-term global observations of the land surface, biosphere, solid Earth, atmosphere, and oceans." On their website, visitors can learn about the EOS's various projects and initiatives via their in-house newsletter, "The Earth Observer," and by looking at their vast collection of images captured by satellites. Users can select the Images by Mission drop-down menu to peruse images from fifteen different missions, including Aquarius, ICESat, and SeaWinds. The site also contains a Communications area, which offers up key publications, educational posters, calendars, booklets, and facet sheets. [KMG

2013-07-01

128

Land mobile satellite system requirements  

NASA Astrophysics Data System (ADS)

A Land Mobile Satellite System (LMSS) provides voice, data and related communications services to moving vehicles and persons. Communications between the mobiles and satellite are in the 806-890 MHz band. The satellite translates these signals to a ""fixed services band'' such as 14/12 GHz band (Ku-band), and communicates in this band with fixed terminals called gateways. The gateways are located at convenient places such as telephone switches (which provide entry into the national telephone system), dispatcher headquarters, computer centers, etc. Communications are therefore principally mobile to fixed. A third communications link, also at Ku-band, is needed between the satellite and a single fixed ground station. This link provides satellite command, telemetry and ranging and also provides a network control function. The latter, through a common signalling system, receives requests and assigns channel slots, and otherwise controls, monitors and polices the network and collects billing information.

Kiesling, J. D.

1983-05-01

129

Land mobile satellite system requirements  

NASA Technical Reports Server (NTRS)

A Land Mobile Satellite System (LMSS) provides voice, data and related communications services to moving vehicles and persons. Communications between the mobiles and satellite are in the 806-890 MHz band. The satellite translates these signals to a ""fixed services band'' such as 14/12 GHz band (Ku-band), and communicates in this band with fixed terminals called gateways. The gateways are located at convenient places such as telephone switches (which provide entry into the national telephone system), dispatcher headquarters, computer centers, etc. Communications are therefore principally mobile to fixed. A third communications link, also at Ku-band, is needed between the satellite and a single fixed ground station. This link provides satellite command, telemetry and ranging and also provides a network control function. The latter, through a common signalling system, receives requests and assigns channel slots, and otherwise controls, monitors and polices the network and collects billing information.

Kiesling, J. D.

1983-01-01

130

Satellite power systems \\/SPS\\/ overview  

Microsoft Academic Search

The concept of using a number of very large satellites in geostationary equatorial orbit to convert solar energy into electricity and then to microwave energy transmitted back to earth is given a brief historical overview. The major program elements and organizational responsibilities in the DOE\\/NASA program for satellite power systems are schematized. The timetable calls for preliminary program recommendations in

R. I. Larock

1978-01-01

131

Laser System for Satellite Geodesy.  

National Technical Information Service (NTIS)

A noval laser system designed and developed for satellite illumination is based on the use of two ruby lasers. It obtains range with a Q-switched laser and angular information by photographing satellite-reflected high-energy normal-mode laser pulses again...

R. L. Iliff

1970-01-01

132

Satellite observations of transionospheric pulse pairs  

SciTech Connect

The BLACKBEARD payload aboard the ALEXIS satellite has been making broadband observations in the VHF band of the radio spectrum. Since November of 1993 several hundred unusual signals have been recorded. The peculiar nature of these bursts of radio noise is that they have a duration of approximately 10 {mu}sec, are typically 20 to 40 dB brighter than the average background, and occur in pairs separated by approximately 50 {mu}sec. The authors have dubbed these emissions TransIonospheric Pulse Pairs, or TIPP events. They do not know what the source of these emissions is, but the dispersion of these signals is consistent with an origin at or near the earth`s surface. The satellite field of view and time of day when TIPP events are generally detected are consistent with regions of thunderstorm activity such as south-central Africa or Indonesia. 4 refs., 5 figs.

Holden, D.N.; Munson, C.P.; Devenport, J.C. [Los Alamos National Lab., NM (United States)] [Los Alamos National Lab., NM (United States)

1995-04-15

133

Satellite bus design for the multiple satellite system  

NASA Astrophysics Data System (ADS)

Current military communications systems employ geosynchronous satellites as the primary element for data relay and transmission. Failure of a single satellite could seriously impair communications capabilities, possibly jeopardizing national security. An alternative to survivable geosynchronous satellites for military communications and data links is a concept in which communications are effected via a network of relatively inexpensive, low-earth-orbiting satellites. The Multiple Satellite System (MSS) concept will provide a cost-effective, highly reliable communications network that will ensure a minimum level of communications during crisis situations. Astro-Space Division (Astro) has completed a one-year preliminary study that defines low-cost MSS satellite bus concepts. This paper discusses satellite design/cost trade studies, recommended approaches for the satellite system and subsystems, and dispenser concepts for low-cost launch that Astro has developed for the Multiple Satellite System Program (MSSP).

Clopp, H. William; Osborn, Leroy W.

134

Satellite Observations for Detecting and Tracking Changes in Atmospheric Composition  

NASA Technical Reports Server (NTRS)

The satellite observations provide constraints on detailed atmospheric modeling, including emissions inventories, indications of transport, harmonized data over vast areas suitable for trends analysis, and a link between spatial scales ranging from local to global, and temporal scales from diurnal to interannual. 1 The National Oceanic and Atmospheric Administration's (NOAA) long-term commitments help provide these observations in cooperation with international meteorological organizations. NASA s long-term commitments will advance scientifically important observations as part of its Earth Science Program, and will assist the transition of the science measurements to applied analyses through the Applied Science Program. Both NASA and NOAA have begun to provide near realtime data and tools to visualize and analyze satellite data,2 while maintaining data quality, validation, and standards. Consequently, decision-makers can expect satellite data services to support air quality decision making now and in the future. The international scientific community's Integrated Global Atmosphere Chemistry Observation System Report3 outlined a plan for ground-based, airborne and satellite measurements and models to integrate the observations into a four-dimensional representation of the atmosphere (space and time) to support assessment and policy information needs. This plan is being carried out under the Global Earth Observation System of Systems (GEOSS). Demonstrations of such an integrated capability4 provide new understanding of the changing atmosphere and link policy decisions to benefits for society. In this article, we highlight the use of satellite data to constrain biomass burning emissions, to assess oxides of nitrogen (NO(x)) emission reductions, and to contribute to state implementation plans, as examples of the use of satellite observations for detecting and tracking changes in atmospheric composition.

Neil, Doreen O.; Kondragunbta, Shobha; Osterman, Gregory; Pickering, Kenneth; Pinder, Robert W.; Prados, Ana I.; Szykman, James

2009-01-01

135

Decadal record of satellite carbon monoxide observations  

NASA Astrophysics Data System (ADS)

Atmospheric carbon monoxide (CO) distributions are controlled by anthropogenic emissions, biomass burning, transport and oxidation by reaction with the hydroxyl radical (OH). Quantifying trends in CO is therefore important for understanding changes related to all of these contributions. Here we present a comprehensive record of satellite observations from 2000 through 2011 of total column CO using the available measurements from nadir-viewing thermal infrared instruments: MOPITT, AIRS, TES and IASI. We examine trends for CO in the Northern and Southern Hemispheres along with regional trends for Eastern China, Eastern USA, Europe and India. We find that all the satellite observations are consistent with a modest decreasing trend ~ -1 % yr-1 in total column CO over the Northern Hemisphere for this time period and a less significant, but still decreasing trend in the Southern Hemisphere. Although decreasing trends in the United States and Europe have been observed from surface CO measurements, we also find a decrease in CO over E. China that, to our knowledge, has not been reported previously. Some of the interannual variability in the observations can be explained by global fire emissions, but the overall decrease needs further study to understand the implications for changes in anthropogenic emissions.

Worden, H. M.; Deeter, M. N.; Frankenberg, C.; George, M.; Nichitiu, F.; Worden, J.; Aben, I.; Bowman, K. W.; Clerbaux, C.; Coheur, P. F.; de Laat, A. T. J.; Detweiler, R.; Drummond, J. R.; Edwards, D. P.; Gille, J. C.; Hurtmans, D.; Luo, M.; Martínez-Alonso, S.; Massie, S.; Pfister, G.; Warner, J. X.

2013-01-01

136

Evaluation of the model representation of the evolution of convective systems using satellite observations of outgoing longwave radiation  

NASA Astrophysics Data System (ADS)

We introduce a technique for assessing the diurnal development of convective storm systems based on outgoing longwave radiation fields. Using the size distribution of the storms measured from a series of images, we generate an array in the length scale-time domain based on the standard score statistic. It demonstrates succinctly the size evolution of storms as well as the dissipation kinematics. It also provides evidence related to the temperature evolution of the cloud tops. We apply this approach to a test case comparing observations made by the Geostationary Earth Radiation Budget instrument to output from the Met Office Unified Model run at two resolutions. The 12 km resolution model produces peak convective activity on all length scales significantly earlier in the day than shown by the observations and no evidence for storms growing in size. The 4 km resolution model shows realistic timing and growth evolution, although the dissipation mechanism still differs from the observed data.

Pearson, K. J.; Hogan, R. J.; Allan, R. P.; Lister, G. M. S.; Holloway, C. E.

2010-10-01

137

Meteorological Satellites (METSAT) and Earth Observing System (EOS) Advanced Microwave Sounding Unit-A (AMSU-A) Failure Modes and Effects Analysis (FMEA) and Critical Items List (CIL)  

NASA Technical Reports Server (NTRS)

This Failure Modes and Effects Analysis (FMEA) is for the Advanced Microwave Sounding Unit-A (AMSU-A) instruments that are being designed and manufactured for the Meteorological Satellites Project (METSAT) and the Earth Observing System (EOS) integrated programs. The FMEA analyzes the design of the METSAT and EOS instruments as they currently exist. This FMEA is intended to identify METSAT and EOS failure modes and their effect on spacecraft-instrument and instrument-component interfaces. The prime objective of this FMEA is to identify potential catastrophic and critical failures so that susceptibility to the failures and their effects can be eliminated from the METSAT/EOS instruments.

1996-01-01

138

Students as Ground Observers for Satellite Cloud Retrieval Validation  

NASA Technical Reports Server (NTRS)

The Students' Cloud Observations On-Line (S'COOL) Project was initiated in 1997 to obtain student observations of clouds coinciding with the overpass of the Clouds and the Earth's Radiant Energy System (CERES) instruments on NASA's Earth Observing System satellites. Over the past seven years we have accumulated more than 9,000 cases worldwide where student observations are available within 15 minutes of a CERES observation. This paper reports on comparisons between the student and satellite data as one facet of the validation of the CERES cloud retrievals. Available comparisons include cloud cover, cloud height, cloud layering, and cloud visual opacity. The large volume of comparisons allows some assessment of the impact of surface cover, such as snow and ice, reported by the students. The S'COOL observation database, accessible via the Internet at http://scool.larc.nasa.gov, contains over 32,000 student observations and is growing by over 700 observations each month. Some of these observations may be useful for assessment of other satellite cloud products. In particular, some observing sites have been making hourly observations of clouds during the school day to learn about the diurnal cycle of cloudiness.

Chambers, Lin H.; Costulis, P. Kay; Young, David F.; Rogerson, Tina M.

2004-01-01

139

Meteorological Satellites (METSAT) and Earth Observing System (EOS) Advanced Microwave Sounding Unit-A (AMSU-A) Stress Analysis Report  

NASA Technical Reports Server (NTRS)

Stress analysis of the primary structure of the Meteorological Satellites Project (METSAT) Advanced Microwave Sounding Units-A, A1 Module using static loads is presented. The structural margins of safety and natural frequency predictions for the METSAT design are reported.

Heffner, Robert

1996-01-01

140

Local Time Distribution of the Anti-Sunward Net Birkeland Current System Deduced from the Oersted Satellite and Ground Observation  

Microsoft Academic Search

From the precise magnetic field measurements by the Oersted satellite at low-altitudes over various local time, a distinct spatial variation at mid- and low- latitudes was detected in the eastward component residuals (Delta B_ phi ) after the subtraction of a geomagnetic main field model. The average Delta B_ phi decreases on the dayside as latitude increases and it increases

S. Yamashita

2001-01-01

141

Middle atmosphere composition revealed by satellite observations  

NASA Technical Reports Server (NTRS)

A series of plots that describe the state of the stratosphere and to some degree, the mesosphere as revealed by satellite observations are shown. The pertinent instrument features, spatial and temporal coverage, and details of accuracy and precision for the experiments providing the data were described. The main features of zonal mean cross sections and polar stereographic projections were noted and intercomparisons were discussed where a parameter was measured by more than one experiment. The main purpose was to collect the available data in one place and provide enough inforamation on limitations or cautions about the data so that they could be used in model comparisons and science studies.

Russell, J. M., III; Solomon, S.; Mccormick, M. P.; Miller, A. J.; Barnett, J. J.; Jones, R. L.; Rusch, D. W.

1986-01-01

142

Water Electrolysis Satellite Propulsion System.  

National Technical Information Service (NTIS)

A water electrolysis satellite propulsion system capable of providing 100,000 pound-seconds of impulse during a seven year life was fabricated and tested in three modes of operation -- simple blowdown, helium repressurization and repressurization by oxyge...

J. G. Campbell R. C. Stechman

1973-01-01

143

Decadal Record of Satellite Carbon Monoxide Observations  

NASA Astrophysics Data System (ADS)

Atmospheric carbon monoxide (CO) distributions are controlled by anthropogenic emissions, biomass burning, chemical production, transport and oxidation by reaction with the hydroxyl radical (OH). Quantifying trends in CO is therefore important for understanding changes related to all of these contributions. Here we present a comprehensive record of satellite observations from 2000 through 2011 of total column CO using the available measurements from nadir-viewing thermal infrared instruments: MOPITT, AIRS, TES and IASI. We examine trends for CO in the Northern and Southern hemispheres along with regional trends for E. China, E. USA, Europe and India. Measurement and sampling methods for each of the instruments are discussed, and we show diagnostics for systematic errors in MOPITT trends. We find that all the satellite observations are consistent with a modest decreasing trend around -1%/year in total column CO over the Northern hemisphere for this time period. Decreasing trends in total CO column are observed for the United States, Europe and E. China with more than 2? significance. For India, the trend is also decreasing, but smaller in magnitude and less significant. Decreasing trends in surface CO have also been observed from measurements in the U.S. and Europe. Although less information is available for surface CO in China, there is a decreasing trend reported for Beijing. Some of the interannual variability in the observations can be explained by global fire emissions, and there may be some evidence of the global financial crisis in late 2008 to early 2009. But the overall decrease needs further study to understand the implications for changes in anthropogenic emissions.

Worden, Helen; Deeter, Merritt; Frankenberg, Christian; George, Maya; Nichitiu, Florian; Worden, John; Aben, Ilse; Bowman, Kevin; Clerbaux, Cathy; Coheur, Pierre-Francois; de Laat, Jos; Warner, Juying; Drummond, James; Edwards, David; Gille, John; Hurtmans, Daniel; Ming, Luo; Martinez-Alonso, Sara; Massie, Steven; Pfister, Gabriele

2013-04-01

144

EROS SYSTEM - SATELLITE ORBIT AND CONSTELLATION DESIGN  

Microsoft Academic Search

The EROS (Earth Resources Observation System) program conducted by ImageSat International N.V. intends to operate a constellation of 8 commercial imaging satellites in LEO (Low Earth Orbit). The first satellite, EROS-A1, was successfully launched by a Russian START-1 launcher on December 5th, 2000, and is presently successfully operating with 1.8 meter to 1.0-meter resolution. This article presents the requirements and

Moshe Bar-Lev; Leonid Shcherbina; Vola Levin

2001-01-01

145

Study of ENSO Using Satellite Observations  

NASA Astrophysics Data System (ADS)

Observations within the last 1 to 1.5 decades indicate that the El Niño warm sea surface temperature (SST) anomalies have peaked more often in the central Pacific than in the eastern Pacific. The advection of the eastern edge of western Pacific warm pool (WPWP) plays an important role modulating the SST in the central Pacific, and satellite observations provide high-resolution information to understand the dynamics in this area. The Aquarius satellite data resolves much more detailed structures of the salinity front (SF) along the eastern edge of WPWP than the in situ observations (i.e. Argo). Together with zonal currents from Ocean Surface Current Analyses Real-Time product (OSCAR), we calculate the advection of the SF at the equator, which is important for three reasons: First, the advection of the SF affects formation the barrier layer (BL), which can further influence the behavior of ENSO. Second, the east-west SF migration is a prominent feature of ENSO variability. For example, during the 2011 La Niña, the salinity front was advected westward, resulting in much higher salinity in the western Pacific compared to the neutral year in 2012. Third, we can analyze how the ocean compensates for the large vertical net freshwater flux (~3 m yr-1) into the warm pool region using simple salt budget analysis. During the boreal fall, Aquarius reveals the strong SF in line with the north-south zonal bounds of the whole Pacific ITCZ rain band centered at about 8-10°N, which is also aligned with boundaries between the zonal equatorial current and counter current. At the same time, the thick barrier layers underneath the ITCZ are also observed. In this study, we apply the first two+ years (25 August 2011 - present) of Aquarius data to describe the correlations among the SF, surface currents, precipitation and the BL in the whole tropical Pacific basin, and discuss findings in the context of ENSO prediction and model comparisons.

Kao, H.; Lagerloef, G. S.

2013-12-01

146

The data distribution satellite system  

NASA Technical Reports Server (NTRS)

The Data Distributed Satellite (DDS) will be capable of providing the space research community with inexpensive and easy access to space payloads and space data. Furthermore, the DDS is shown to be a natural outgrowth of advances and evolution in both NASA's Space Network and commercial satellite communications. The roadmap and timescale for this evolution is described along with key demonstrations, proof-of-concept models, and required technology development that will support the projected system evolution toward the DDS.

Bruno, Ronald C.; Weinberg, Aaron

1991-01-01

147

Satellite Snow Observations and Seasonal Streamflow Forecasts.  

National Technical Information Service (NTIS)

Relatively low spatial resolution (about 4 km) environmental satellite and high spatial resolution (80m) earth resources satellite data have been used to map snowcovered areas occurring in the upper Indus River Basin in Pakistan and the Wind River Mountai...

A. Rango V. V. Salomonson

1976-01-01

148

Seasonal Streamflow Estimation Employing Satellite Snowcover Observations.  

National Technical Information Service (NTIS)

Low resolution meteorological satellite and high resolution earth resources satellite data have been used to map snow covered area over the upper Indus River and the Wind River Mountains of Wyoming, respectively. For the Indus River early spring snow cove...

A. Rango V. V. Salomonson J. L. Foster

1975-01-01

149

Semi-diurnal variation of surface rainfall studied from global cloud-system resolving model and satellite observations  

NASA Astrophysics Data System (ADS)

We studied the semi-diurnal variation of surface rainfall over southern Africa and the Amazon simulated by a global cloud system resolving model (Nonhydrostatic ICosahedral Atmospheric Model; NICAM) under realistic conditions with land-sea contrast. This semi-diurnal variation was found to be consistent with the Tropical rainfall Measuring Mission (TRMM) and Meteosat-8 observations. The timing of the primary afternoon rainfall peak by the NICAM coincides with TRMM/PR primary afternoon peak, and the secondary early morning peak by the NICAM simulation agree with the TRMM/PR observations within two hours. Mean size of deep convection (DC), defined by 213K of the Meteosat-8 infrared data shows semi-diurnal variation, although the number of DC show diurnal variation with coincident peak with TRMM/PR primary peak. The semi-diurnal variation of the mean size of DC and number of DC is simulated with small secondary peak over southern Africa by NICAM, whose DC is defined by OLR smaller than 112 W m-2 (corresponding to 213 K in cumulative frequency).

Inoue, T.; Rajendran, K.; Satoh, M.; Miura, H.; Schmetz, J.

2012-11-01

150

Investigations of earth dynamics from satellite observations  

NASA Technical Reports Server (NTRS)

The consequences of the earth's elasticity are examined for close-earth satellites. The ideas of polar motion and earth tides are developed in a form applicable to satellite studies, since the polar motion, the body tide, and the ocean tide are all suitable for study by use of satellites. Analysis of available polar-motion data is performed.

Gaposchkin, E. M.

1973-01-01

151

Satellite observations of current and waves in space plasmas  

NASA Technical Reports Server (NTRS)

Plasma processes occurring in the magnetosphere are examined in the light of recent observations of currents and waves with satellite-born magnetic experiments. In particular, results from the Viking and AMPTE/CCE satellites indicate that geomagnetic field lines that guide stationary Birkland currents can also support resonant Alfven waves. The relationship of these waves to the current systems and their source in the magnetosphere is still under investigation. It is emphasized that Birkland currents and Alfven waves are fundamental to an understanding of the earth's plasma environment.

Potemra, T. A.; Zanetti, L. J.; Erlandson, R. E.; Bythrow, P. F.; Engebretson, M. J.

1988-01-01

152

Advanced satellite communication system  

NASA Technical Reports Server (NTRS)

The objective of this research program was to develop an innovative advanced satellite receiver/demodulator utilizing surface acoustic wave (SAW) chirp transform processor and coherent BPSK demodulation. The algorithm of this SAW chirp Fourier transformer is of the Convolve - Multiply - Convolve (CMC) type, utilizing off-the-shelf reflective array compressor (RAC) chirp filters. This satellite receiver, if fully developed, was intended to be used as an on-board multichannel communications repeater. The Advanced Communications Receiver consists of four units: (1) CMC processor, (2) single sideband modulator, (3) demodulator, and (4) chirp waveform generator and individual channel processors. The input signal is composed of multiple user transmission frequencies operating independently from remotely located ground terminals. This signal is Fourier transformed by the CMC Processor into a unique time slot for each user frequency. The CMC processor is driven by a waveform generator through a single sideband (SSB) modulator. The output of the coherent demodulator is composed of positive and negative pulses, which are the envelopes of the chirp transform processor output. These pulses correspond to the data symbols. Following the demodulator, a logic circuit reconstructs the pulses into data, which are subsequently differentially decoded to form the transmitted data. The coherent demodulation and detection of BPSK signals derived from a CMC chirp transform processor were experimentally demonstrated and bit error rate (BER) testing was performed. To assess the feasibility of such advanced receiver, the results were compared with the theoretical analysis and plotted for an average BER as a function of signal-to-noise ratio. Another goal of this SBIR program was the development of a commercial product. The commercial product developed was an arbitrary waveform generator. The successful sales have begun with the delivery of the first arbitrary waveform generator.

Staples, Edward J.; Lie, Sen

1992-01-01

153

Applications for specialized satellite systems in Europe  

NASA Astrophysics Data System (ADS)

The applications of satellite digital communication which will be made available to European customers by the multiservice repeaters included in the first-generation Eutelsat satellites and in the French Telecom-1 are surveyed. The history of European communications-satellite development and current planning for additional spacecraft are outlined. The general configuration for the applications systems involves 'community-type' earth stations linked to terrestrial networks of users. The specific applications dicussed include intracompany applications (electronic office, communicating word-processor, facsimile transmission, computer-file and graphic transfer, teleconferencing, and local-area networks), the electronic library, telemetry from observation satellites, remote printing of newspapers, wideband teletex, and the remote diagnosis of software and computer systems.

Hanell, S.

154

Applications systems verification and transfer project. Volume 3: Operational applications of satellite snow cover observations in California  

NASA Technical Reports Server (NTRS)

Five southern Sierra snowmelt basins and two northern Sierra-Southern Cascade snowmelt basins were used to evaluate the effect on operational water supply forecasting from satellite imagery. Manual photointerpretation techniques were used to obtain SCA and equivalent snow line for the years 1973 to 1979 for the seven test basins using LANDSAT imagery and GOES imagery. The use of SCA was tested operationally in 1977-79. Results indicate the addition of SCA improve the water supply forecasts during the snowmelt phase for these basins where there may be an unusual distribution of snowpack throughout the basin, or where there is a limited amount of real time data available. A high correlation to runoff was obtained when SCA was combined with snow water content data obtained from reporting snow sensors.

Brown, A. J.; Hannaford, J. F.

1981-01-01

155

Temporal and spatial variations of global deep cloud systems based on CloudSat and CALIPSO satellite observations  

NASA Astrophysics Data System (ADS)

The spatial and temporal global distribution of deep clouds was analyzed using a four-year dataset (2007-10) based on observations from CloudSat and CALIPSO. Results showed that in the Northern Hemisphere, the number of deep cloud systems (DCS) reached a maximum in summer and a minimum in winter. Seasonal variations in the number of DCS varied zonally in the Southern Hemisphere. DCS occurred most frequently over central Africa, the northern parts of South America and Australia, and Tibet. The mean cloud-top height of deep cloud cores (TDCC) decreased toward high latitudes in all seasons. DCS with the highest TDCC and deepest cores occurred over east and south Asian monsoon regions, west-central Africa and northern South America. The width of DCS (WDCS) increased toward high latitudes in all seasons. In general, DCS were more developed in the horizontal than in the vertical direction over high latitudes and vice versa over lower latitudes. Findings from this study show that different mechanisms are behind the development of DCS at different latitudes. Most DCS at low latitudes are deep convective clouds which are highly developed in the vertical direction but cover a relatively small area in the horizontal direction; these DCS have the highest TDCC and smallest WDCS. The DCS at midlatitudes are more likely to be caused by cyclones, so they have less vertical development than DCS at low latitudes. DCS at high latitudes are mainly generated by large frontal systems, so they have the largest WDCS and the smallest TDCC.

Peng, Jie; Zhang, Hua; Li, Zhanqing

2014-05-01

156

Defining Requirements for Future Satellite Air Quality Chemistry Observations  

NASA Astrophysics Data System (ADS)

If a satellite mission related to atmospheric composition and air quality is to become a reality within the next decade, the atmospheric chemistry community will need to establish clear scientific motivation for the new measurements. For this, there is considerable interest in using chemical observing system simulation experiment (OSSE) studies to help define quantitative measurement requirements for satellite missions and to evaluate the expected performance of proposed observing strategies. These experiments will hopefully provide a practical way of defining a traceability matrix mapping science requirements through measurement requirements onto instrument requirements. OSSEs must be driven by well-defined scientific questions and the experiment formulation constructed accordingly. We present a framework for this comprising the following key elements: (1) a science-driven requirement for a chemical species observation, (2) a satellite instrument simulator and observing strategy that might be capable of making a useful measurement, (3) a simulated retrieval of the species with nature defined by an appropriate chemical transport model, (4) a forecast of the species distribution using an assimilation of the retrieval in the model, and (5) a quantitative assessment of the value of the measurement. This will be illustrated with an example OSSE motivated by the desire to measure the distribution and time evolution of carbon monoxide in the lower-most troposphere for air quality applications using candidate satellite multispectral measurements in the thermal and near infrared.

Edwards, D. P.; Arellano, A.; Deeter, M. N.

2007-12-01

157

Progressive Communication Satellite Systems Design  

Microsoft Academic Search

This paper describes the progressive design, on a phased basis, of a typical communication satellite system capable of meeting a variety of military and civilian applications, The system philosophy stresses reliability and flexibility of operation, with provision for both point-to-point and area coverage, to serve both fixed and mobile ground terminals, and to operate in either a military or nonmilitary

J. E. Bartow; D. L. Jacoby; G. N. Krassner

1960-01-01

158

Multiple beam satellite system optimization  

Microsoft Academic Search

An analytical method is developed for determining the basic RF link parameters that are required in a satellite system design. Certain simplifying assumptions are required and specific system elements are selected. Two different design criteria are considered: optimizing the per-beam signal energy to noise spectral density ratio and minimizing the per-user costs. These two criteria are complements of each other

T. P. McGarty; T. H. Warner

1977-01-01

159

Multi-Satellite Observations of Oceanic Lightning  

NASA Technical Reports Server (NTRS)

This paper will present several case studies of active oceanic lightning storms. Measurements by instruments on the Tropical Rainfall Measuring Mission (TRMM) and Fast On-orbit Recording of Transient Events (FORTE) platforms demonstrate that the two sets of sensors reinforce and complement one another. There is spatial and temporal coincidence between the optical data sets from Lightning Imaging Sensor (LIS) on TRMM and the photo-diode detector on FORTE. The LIS flash analysis provides a framework to interpret the stroke level data from FORTE. For these cases, the VHF receiver on FORTE is slaved to the optical system to provide stroke level radio frequency (RF) diagnostics. The occasions when TRMM and FORTE simultaneously have a lightning storm in their overlapping fields of view are extremely rare. One case study in the Gulf of Mexico is within range of land based sensor networks. These networks confirm the interpretation of satellite data and well as provide context for the storm conditions.

Boeck, W. L.; Jacobson, A. R.; Christian, H. J.; Goodman, S. J.

2003-01-01

160

Use of Earth Observing Satellites for Operational Hazard Support  

NASA Astrophysics Data System (ADS)

The National Oceanic and Atmospheric Administration (NOAA) relies on Earth observing satellite data to carry out its operational mission to monitor, predict, and assess changes in the Earth's atmosphere, land, and oceans. NOAA's National Environmental Satellite, Data, and Information Service (NESDIS) uses satellite data to help lessen the impacts of natural and man-made disasters due to tropical cyclones, flash floods, heavy snowstorms, volcanic ash clouds (for aviation safety), sea ice (for shipping safety), and harmful algal blooms. Communications systems on NOAA satellites are used to support search and rescue and to relay data from data collection platforms to a variety of users. NOAA's Geostationary (GOES) and Polar (POES) Operational Environmental Satellites are used in conjunction with other satellites to support NOAA's operational mission. While NOAA's National Hurricane Center is responsible for predicting tropical cyclones affecting the U.S. mainland, NESDIS continuously monitors the tropics world wide, relaying valuable satellite interpretations of tropical systems strength and position to users throughout the world. Text messages are sent every six hours for tropical cyclones in the Western Pacific, South Pacific, and Indian Oceans. To support the monitoring, prediction, and assessment of flash floods and winter storms, NESDIS sends out text messages alerting U.S. weather forecast offices whenever NOAA satellite imagery indicates the occurrence of heavy rain or snow. NESDIS also produces a 24-hour rainfall composite graphic image covering those areas affected by heavy precipitation. The International Civil Aviation Organization (ICAO) and other aviation concerns recognized the need to keep aviators informed of volcanic hazards. To that end, nine Volcanic Ash Advisory Centers (VAAC's) were created to monitor volcanic ash plumes within their assigned airspace. NESDIS hosts one of the VAAC's. Although the NESDIS VAAC's primary responsibility is the continental U.S., Carribean, and adjacent oceans, it also tracks volcanic eruptions throughout the world. Text messages are produced along with graphic interpretations. This information, along with volcanic ash forecasts produced by NOAA's National Weather Service, is made available to U.S. Government and international agencies concerned with aviation, seismology, and climate analysis. Earth observing satellites help NESDIS to ensure safe navigation of ships through sea ice by measuring the extent, thickness, and age of ice as well as sea surface winds over the polar regions of the globe, coastal areas, and inland waterways. These satellites also help NESDIS to monitor U.S. coastal areas for dangerous algal blooms or other toxic effects to fish and sea mammals as well as monitoring floods and fires. Experimental fire products can help in the monitoring of fires and fire weather, as well as determining fire risk. Experimental soil moisture products support flood and drought monitoring. Flood extent and damage assessment for a variety of hazards can be determined from several satellites at varying spatial resolutions. The Search and Rescue Satellite Aided Tracking (SARSAT) system detects and locates persons in distress on land or water. NOAA satellites relay distress signals from emergency beacons through a network of ground stations to the U.S. Mission Control Center (USMCC). The USMCC processes the data and alerts the appropriate search and rescue authorities. SARSAT is part of the international Cospas-Sarsat Program. NOAA's GOES Data Collection (DCS) and Argos (jointly with the French space agency) POES Data Collection and Locations Systems transmit data collected from remote land and water based platforms and distributes the data to researchers, governmental and environmental organizations worldwide. The GOES DCS system allows near real time and frequent transmissions, e.g. hourly, over the Americas and much of the Atlantic and Eastern Pacific Oceans. ARGOS transmissions are less frequent, but global and provide the location of moving platforms such as animals and d

Wood, H. M.; Lauritson, L.

161

Global Precipitation Analysis Using Satellite Observations  

NASA Technical Reports Server (NTRS)

Global precipitation analysis covering the last few decades and the impact of the new TRMM (Tropical Rainfall Measuring Mission) observations are reviewed in the context of weather and climate applications. All the data sets discussed are the result of mergers of information from multiple satellites and gauges, where available. The focus of the talk is on TRMM-based 3 hr. analyses that use TRMM to calibrate polar-orbit microwave observations from SSM/I (and other satellites) and geosynchronous IR observations and merges the various calibrated observations into a final, 3 hr. resolution map. This TRMM standard product will be available for the entire TRMM period (January 1998-present) at the end of 2002. A real-time version of this merged product is being produced and is available at 0.25 deg latitude-longitude resolution over the latitude range from 50 deg N-50 deg S. Examples will be shown, including its use in monitoring flood conditions and in relating weather-scale patterns to climate-scale patterns. The 3-hourly analysis is placed in the context of two research products of the World Climate Research Program's (WCRP/GEWEX) Global Precipitation Climatology Project (GPCP). The first is the 23 year, monthly, globally complete precipitation analysis that is used to explore global and regional variations and trends and is compared to the much shorter TRMM tropical data set. The GPCP data set shows no significant global trend in precipitation over the twenty years, unlike the positive trend in global surface temperatures over the past century. Regional trends are also analyzed. A trend pattern that is a combination of both El Nino and La Nina precipitation features is evident in the Goodyear data set. This pattern is related to an increase with time in the number of combined months of El Nino and La Nina during the 23 year period. Monthly anomalies of precipitation are related to ENSO variations with clear signals extending into middle and high latitudes of both hemispheres. Also shown is the GPCP daily, 1 deg latitude-longitude analysis, which is available from January 1997 to the present. Plans to incorporate the TRMM data and 3-hourly analysis into the GPCP products are outlined. The outcome should be an improved global analysis and climatology on monthly scales for the 23 year period and finer time scale analyses for more recent periods, including real-time 3-hourly (or finer) analyses over much of the globe.

Adler, Robert F.; Huffman, George; Curtis, Scott; Bolvin, David; Nelkin, Eric

2002-01-01

162

Inferring Land Surface Model Parameters for the Assimilation of Satellite-Based L-Band Brightness Temperature Observations into a Soil Moisture Analysis System  

NASA Technical Reports Server (NTRS)

The Soil Moisture and Ocean Salinity (SMOS) satellite mission provides global measurements of L-band brightness temperatures at horizontal and vertical polarization and a variety of incidence angles that are sensitive to moisture and temperature conditions in the top few centimeters of the soil. These L-band observations can therefore be assimilated into a land surface model to obtain surface and root zone soil moisture estimates. As part of the observation operator, such an assimilation system requires a radiative transfer model (RTM) that converts geophysical fields (including soil moisture and soil temperature) into modeled L-band brightness temperatures. At the global scale, the RTM parameters and the climatological soil moisture conditions are still poorly known. Using look-up tables from the literature to estimate the RTM parameters usually results in modeled L-band brightness temperatures that are strongly biased against the SMOS observations, with biases varying regionally and seasonally. Such biases must be addressed within the land data assimilation system. In this presentation, the estimation of the RTM parameters is discussed for the NASA GEOS-5 land data assimilation system, which is based on the ensemble Kalman filter (EnKF) and the Catchment land surface model. In the GEOS-5 land data assimilation system, soil moisture and brightness temperature biases are addressed in three stages. First, the global soil properties and soil hydraulic parameters that are used in the Catchment model were revised to minimize the bias in the modeled soil moisture, as verified against available in situ soil moisture measurements. Second, key parameters of the "tau-omega" RTM were calibrated prior to data assimilation using an objective function that minimizes the climatological differences between the modeled L-band brightness temperatures and the corresponding SMOS observations. Calibrated parameters include soil roughness parameters, vegetation structure parameters, and the single scattering albedo. After this climatological calibration, the modeling system can provide L-band brightness temperatures with a global mean absolute bias of less than 10K against SMOS observations, across multiple incidence angles and for horizontal and vertical polarization. Third, seasonal and regional variations in the residual biases are addressed by estimating the vegetation optical depth through state augmentation during the assimilation of the L-band brightness temperatures. This strategy, tested here with SMOS data, is part of the baseline approach for the Level 4 Surface and Root Zone Soil Moisture data product from the planned Soil Moisture Active Passive (SMAP) satellite mission.

Reichle, Rolf H.; De Lannoy, Gabrielle J. M.

2012-01-01

163

Military Satellite Communications Systems.  

National Technical Information Service (NTIS)

MILSATCOM systems consist of three primary segments: earth terminal (airborne, ground, sea) segment, sp segment, and control segment. MILSATCOM systems are vital to Department of Defense as they satisfy certain essential communications connectivity needs ...

1992-01-01

164

Using the JPL Tropical Cyclone Information System to study the climatology of hurricane precipitation structure from 10 years of passive microwave satellite observations in the Atlantic  

NASA Astrophysics Data System (ADS)

In spite of recent improvements in hurricane track forecast accuracy, currently there are still many unanswered questions about the physical processes that determine hurricane genesis, and evolution. Furthermore, a significant amount of work remains to be done in validating and improving hurricane forecast models. None of this can be accomplished without a comprehensive set of multi-parameter observations that are relevant to both the large-scale and the storm-scale processes in the atmosphere and in the ocean. Despite the significant amount of satellite observations today, they are still underutilized in hurricane research and operations, due to complexity and volume. To facilitate hurricane research, we developed the JPL Tropical Cyclone Information System (TCIS) of multi-instrument satellite observations pertaining to: i) the thermodynamic and microphysical structure of the storms; ii) the air-sea interaction processes; iii) the larger-scale environment as depicted by the SST and the Total Precipitable Water of the environment (Hristova-Veleva et al., 2008, 2011). Our goal was to create a one-stop place to provide the researchers with an extensive set of observed hurricane data, and their graphical representation, organized in an easy way to determine when coincident observations from multiple instruments are available. In this study we use the 10+ years of passive microwave observations of Atlantic hurricanes to create composite structures that are segregated by hurricane category and by intensification rate. The use of composite structures provides a statistically robust framework (e.g. Rogers et al., 2012). We analyze the storm asymmetry as depicted by several factors - brightness temperatures and their derivatives such as a newly-develop Rain Indicator and a new convective/stratiform separation that is based on the value and the spatial variability of this Rain Indicator. The goal is to determine whether the storm morphology (in particular, the storm asymmetry or lack thereof) carries predictive skills regarding the potential for intensification. The presentation will describe the JPL TCIS and the results of our analysis of the passive microwave satellite observations of the Atlantic hurricanes. Refernces: Hristova-Veleva, S. M., C. Ao, Y. Chao, V. Dang, R. Fovell, M. Garay, Z. Haddad, B. Knosp, B. Lambrigtsen, P. P. Li, K. J. Park, W. Poulsen, H. Su, S. Tanelli, D. Vane, Q. A. Vu, J. Willis, D. L. Wu, 2008: "Using the JPL Tropical Cyclone Information System for Research and Applications", AMS 28th Hurricane and Tropical Meteorology Conference, Orlando, FL, 28Apr.-02May 2008 Hristova-Veleva, S. M., A. Chau, Z. Haddad, B. Knosp, B. Lambrigtsen, P. P. Li, E. Rodriguez, T. -. P. Shen, B. Stiles, H. Su, J. Turk, and Q. Vu, 2011: "Impact of microphysical parameterizations on the structure and intensity of simulated hurricanes: Using satellite data to determine the parameterizations that produce most realistic storms", 14th Conference on Mesoscale Processes, 1-4 August 2011, Los Angeles, California Rogers, R., S. Lorsolo, P. Reasor, J. Gamache, F. Marks, 2012: Multiscale Analysis of Tropical Cyclone Kinematic Structure from Airborne Doppler Radar Composites. Mon. Wea. Rev., 140, 77-99.

Hristova-Veleva, Svetla; Haddad, Ziad; Knosp, Brian; Lambrigtsen, Bjorn; Li, P. Peggy; Poulsen, William; Seo, Eun-Kyoung; Shen, Tsae-Pyng; Turk, Francis J.; Vu, Quoc

2013-04-01

165

Satellite Atmosphere and Io Torus Observations  

NASA Technical Reports Server (NTRS)

NASA's Planetary Astronomy Program has supported a vigorous three-year program of groundbased observations and detailed analysis of the Jupiter/Io system. Our work focused on Io's escaping atmosphere and the plasma torus that it creates.

Schneider, Nicholas

2004-01-01

166

Modeling elves observed by FORMOSAT-2 satellite  

NASA Astrophysics Data System (ADS)

The ISUAL experiment on the FORMOSAT-2 satellite has confirmed the existence of ionization and Lyman-Birge-Hopfield (LBH) band emissions in elves. In this paper, an in-depth study of the ISUAL recorded elves was carried out. Numerical simulation results of elves based on an electromagnetic finite difference time domain (FDTD) model of the emissions between 185-800 nm and of their spatial-temporal evolution are presented. To account for the effect of atmospheric attenuation, three major attenuation mechanisms: O2, O3, and molecular Rayleigh scattering are considered. Validations of the electromagnetic FDTD model were conducted in three ways: by comparing the calculated and observed photon fluxes in the ISUAL spectrophotometric channels, by directly comparing the simulated and observed morphologies of elves, and by comparing the computed photon counts of the ISUAL Imager based on the derived peak currents for two elve-associated NLDN (National Lightning Detection Network) cloud-to-ground discharges (CGs) with those recorded by the ISUAL Imager. In all three ways, very good agreement was achieved.

Kuo, Cheng-Ling; Chen, A. B.; Lee, Y. J.; Tsai, L. Y.; Chou, R. K.; Hsu, R. R.; Su, H. T.; Lee, L. C.; Cummer, S. A.; Frey, H. U.; Mende, S. B.; Takahashi, Y.; Fukunishi, H.

2007-11-01

167

Satellite observation of atmospheric nuclear gamma radiation.  

PubMed

We present a satellite observation of the spectrum of gamma radiation from the Earth's atmosphere in the energy interval from 300 keV to 8.5 MeV. The data were accumulated by the gamma ray spectrometer on the Solar Maximum Mission over 3 1/2 years, from 1980 to 1983. The excellent statistical accuracy of the data allows 20 atmospheric line features to be identified. The features are superimposed on a continuum background which is modeled using a power law with index -1.16. Many of these features contain a blend of more than one nuclear line. All of these lines (with the exception of the 511-keV annihilation line) are Doppler broadened. Line energies and intensities are consistent with production by secondary neutrons interacting with atmospheric 14N and 16O. Although we find no evidence for other production mechanisms, we cannot rule out significant contributions from direct excitation or spallation by primary cosmic ray protons. The relative intensities of the observed line features are in fair agreement with theoretical models; however, existing models are limited by the availability of neutron cross sections, especially at high energies. The intensity and spectrum of photons at energies below the 511-keV line, in excess of a power law continuum, can be explained by Compton scattering of the annihilation line photons in traversing an average of approximately 21 g cm-2 of atmosphere. PMID:11537397

Letaw, J R; Share, G H; Kinzer, R L; Silberberg, R; Chupp, E L; Forrest, D J; Rieger, E

1989-02-01

168

Satellite height determination using satellite-to-satellite tracking and ground laser systems  

NASA Technical Reports Server (NTRS)

The height of the GEOS-C spacecraft was utilized as measured by the onboard radar altimeter, for an improved determination of the earth's gravitational field and for the determination of the variation of the physical surface of the oceans. Two tracking system approaches to accurately determine the spacecraft height (orbit) are described and their results stated. These are satellite-to-satellite tracking (SST) and ground laser tracking (GLT). Height variations can be observed in the dm-regions using SST and in the m-region using present GLT.

Vonbun, F. O.

1972-01-01

169

Satellite orbit determination using satellite gravity gradiometry observations in GOCE mission perspective  

NASA Astrophysics Data System (ADS)

Between the years 2004 and 2005 the launch of the first gradiometric satellite is planned. This satellite will be an important element of the Gravity Field and Steady - State Ocean Circulation Explorer Mission (GOCE). This mission is one of the reasons for performing the simulation research of the Satellite Gravity Gradiometry. Our work contains the theory description and simulation results of the satellite orbit determination using the gravity tensor observations. In the process of the satellite orbit determination the initial dynamic state vector corrections are obtained. These corrections are estimated by means of the gravity gradiometry measurements. The performed simulations confirm the possibility of satellite orbit determination by means of the gravity tensor observations.Key words. satellite geodesy, satellite gradiometry, satellite orbits

Boboj?, A.; Dro?yner, A.

2003-06-01

170

Satellite observations of temporal terrestrial features  

NASA Technical Reports Server (NTRS)

The application of satellite data to earth resources and environmental studies and the effects of resolution of the photographs and imagery are discussed. The nature of the data acquired by manned space flight and unmanned satellites is described. Specific applications of remotely sensed data for oceanography, hydrology, geography, and geology are examined.

Rabchevsky, G. A.

1972-01-01

171

Multiple beam satellite system optimization  

Microsoft Academic Search

This paper develops an analytical method for determining the basic RF link parameters that are required in a satellite system design. Two different design criteria are considered: optimizing the per beam signal energy to noise spectral density ratio, and minimizing the per user costs. These two criteria are duals of each other subject to coverage and performance constraints. The model

T. P. McGarty; T. H. Warner

1977-01-01

172

Satellite observations of a monsoon depression  

NASA Technical Reports Server (NTRS)

The exploration of a monsoon depression over Burma and the Bay of Bengal is discussed. Aircraft and satellite data were examined, with an emphasis on the Microwave Sounding Unit (MSU) aboard TIROS-N and the Scanning Multichannel Microwave Radiometer (SMMR) aboard Nimbus-7. The structure of the monsoon depression was found to be dominated by cumulus convection. The only systematic large scale behavior discerned was a propagation of the depression westward, and diurnal migration of contours of brightness temperature. These contours in the middle troposphere showed a gradient toward the north with the patterns migrating northward at night. From SMMR and dropwindsonde data, water vapor contents were found to be near 65 mm, increasing to more than 70 mm in the northeast Bay of Bengal. Cloud water contents reached about three mm. Rainfall rates exceeding 5.7 mm/h occurred over a small part of the storm area, while mean rainfall rates in areas of order 20,000 sq km reached approximately 0.5 mm/h. Measured MSU brightness temperatures were reconciled very well with dropwindsonde data and with airborne in situ observations of clouds (by photography) and hydrometeors (by radar). Diffuse scattering was determined to be important in computing brightness temperature.

Warner, C.

1984-01-01

173

The Mexican national satellite system  

NASA Astrophysics Data System (ADS)

The satellites, tracking, telemetry, command, and monitoring facilities, and the earth station complex for the Mexican national satellite system, Morelos, are described. The spacecraft are intended to provide educational television, rural telephony, data transmission, and business and industrial services. Scheduled for 1985 launch, the satellites will be placed in GEO and use the C and Ku bands with 12 narrow band and six wideband transponders. Spin-stabilized and solar cell powered, the functional mass will be 666 kg, including propellant. The solar panels will provide 940 W of power and 830 W will be available from NiCd batteries during eclipse conditions. The earth station will be located at Iztapalapa, which will have a 12 m antenna, redundant uplink and downlink radios, and command and ranging equipment. Back-up capability will be provided by a station at Tulancingo. Ku band and C band stations are in planning.

Sanchez Ruiz, M. E.; Briskman, R. D.

1983-10-01

174

Monitoring the Climate System with Satellites  

NSDL National Science Digital Library

The international science community has identified a set of Essential Climate Variables (ECVs) that should be monitored for measuring the climate system, how it is changing, and its likely impact on future climate. Environmental satellites play an important role in this effort. They are uniquely positioned to provide broad, spatially consistent, and continuous global sampling of many of the ECVs. This module explores the benefits of monitoring the climate system with satellites. We begin by reviewing how satellites observe key atmospheric elements and features that are found in a variety of climate cycles and are important for studying long-term climate trends. From there, we explore events at the different scales (from seasonal to long-term) and the contributions that satellites make to improving our understanding, monitoring, and prediction of them. Finally, we discuss the challenges involved in monitoring climate with satellites. Among these is the need for continuous, stable, high-resolution, and validated measurements that are coordinated with the worldâs satellite operators.

Dills, Patrick

2012-01-11

175

Use of Earth Observing Satellites for Operational Hazard Support  

Microsoft Academic Search

The National Oceanic and Atmospheric Administration (NOAA) relies on Earth observing satellite data to carry out its operational mission to monitor, predict, and assess changes in the Earth's atmosphere, land, and oceans. NOAA's National Environmental Satellite, Data, and Information Service (NESDIS) uses satellite data to help lessen the impacts of natural and man-made disasters due to tropical cyclones, flash floods,

H. M. Wood; L. Lauritson

2002-01-01

176

Chaotic Dynamics of Satellite Systems  

NASA Astrophysics Data System (ADS)

We consider the problem of calculating the Lyapunov time (the characteristic time of predictable dynamics) of chaotic motion in the vicinity of separatrices of orbital resonances in satellite systems. The primary objects of study are the chaotic regimes that have occurred in the history of the orbital dynamics of the second and fifth Uranian satellites (Umbriel and Miranda) and the first and third Saturnian satellites (Mimas and Tethys). We study the dynamics in the vicinity of separatrices of the resonance multiplets corresponding to the 3 : 1 commensurability of mean motions of Miranda and Umbriel and the multiplets corresponding to the 2 : 1 commensurability of mean motions of Mimas and Tethys. These chaotic regimes have most probably contributed much to the long-term orbital evolution of the two satellite systems. The equations of motion have been numerically integrated to estimate the Lyapunov time in models corresponding to various epochs of the system evolution. Analytical estimates of the Lyapunov time have been obtained by a method (Shevchenko, 2002) based on the separatrix map theory. The analytical estimates have been compared to estimates obtained by direct numerical integration.

Mel'Nikov, A. V.; Shevchenko, I. I.

2005-07-01

177

Titan. [Voyager IRIS observation of satellite atmosphere  

NASA Technical Reports Server (NTRS)

Saturn's satellite Titan is the second-largest in the solar system. Its dense atmosphere is mostly molecular nitrogen with an admixture of methane, a surface pressure of 1.5 bars and a surface temperature of 94K. The fundamental driving force in the long-term evolution of Titan's atmosphere is the photolysis of methane in the stratosphere to form higher hydrocarbons and aerosols. The current rate of photolysis and undersaturation of methane in the lower troposphere suggests the presence of a massive ethane-methane-nitrogen ocean. The ocean evolves to a more ethane-rich state over geologic time, driving changes in the atmospheric thermal structure. An outstanding issue concerning Titan's earliest history is the origin of atmospheric nitrogen: was it introduced into Titan as molecular nitrogen or ammonia? Measurement of the argon-to-nitrogen ratio in the present atmosphere provides a diagnostic test of these competing hypotheses. Many of the questions raised by the Voyager encounters about Titan and its atmosphere can be adequately addressed only by an entry probe, such as that planned for the Cassini mission.

Lunine, Jonathan I.

1990-01-01

178

Operational Applications of Satellite Snowcover Observations  

NASA Technical Reports Server (NTRS)

LANDSAT and NOAA satellites data were used to study snow depth. These snow measurements were used to help forecast runoff and flooding. Many areas of California, Arizona, Colorado, and Wyoming were emphasized.

Rango, A. (editor)

1975-01-01

179

Evaluating NOx Emissions Using Satellite Observations  

NASA Astrophysics Data System (ADS)

Atmospheric NO2 columns retrieved from satellites can provide a useful top-down assessment of bottom-up NOx emissions inventories. We present three case studies of an approach to evaluate NOx emissions at a sector level by comparing satellite retrievals to regional chemical-transport model calculations of NO2 columns. In the first example, the atmospheric impact of implementing NOx controls at eastern US power plants is demonstrated. In the second study, we use NOx monitors at western US power plants to calibrate our satellite-model comparisons. We then apply our approach to evaluate bottom-up estimates of NOx emissions from western US cities. In the third example, we validate our satellite-model approach using in-situ aircraft measurements and assess NOx emissions from power plants, cities, industrial facilities, and ports in eastern Texas. We conclude with some general insights on the usefulness of this approach and suggestions for future areas of research.

Frost, G. J.; Kim, S.; Brioude, J.; McKeen, S. A.; Trainer, M.; Heckel, A.; Hilboll, A.; Richter, A.; Burrows, J. P.; Gleason, J. F.; Boersma, K. F.; Hsie, E.; Lee, S.; Angevine, W. M.; Granier, C.; Peischl, J.; Ryerson, T. B.; Fehsenfeld, F. C.

2012-12-01

180

Evaluating NOx Emissions Using Satellite Observations  

NASA Astrophysics Data System (ADS)

Atmospheric NO2 columns retrieved from satellites can provide a useful top-down assessment of bottom-up NOx emissions inventories. We present three case studies of an approach to evaluate NOx emissions at a sector level by comparing satellite retrievals to regional chemical-transport model calculations of NO2 columns. In the first example, the atmospheric impact of implementing NOx controls at eastern US power plants is demonstrated. In the second study, we use NOx monitors at western US power plants to calibrate our satellite-model comparisons. We then apply our approach to evaluate bottom-up estimates of NOx emissions from western US cities. In the third example, we validate our satellite-model approach using in-situ aircraft measurements and assess NOx emissions from power plants, cities, industrial facilities, and ports in eastern Texas. We conclude with some general insights on the usefulness of this approach and suggestions for future areas of research.

Frost, G. J.; Kim, S.; Trainer, M.; McKeen, S. A.; Lee, S.; Hsie, E.; Heckel, A.; Hilboll, A.; Richter, A.; Burrows, J. P.; Gleason, J. F.; Boersma, F. F.; Granier, C.; Ryerson, T. B.; Peischl, J.

2011-12-01

181

Multiple Beam Satellite System Optimization  

Microsoft Academic Search

An analytical method is developed for determining the basic RF link parameters that are required in a satellite system design. Certain simplifying assumptions are required and specific system elements are selected. Two different design criteria are considered; optimizing the per-beam signal energy to noise spectral density ratio (Eb\\/N0), and minimizing the per-user costs. These two criteria are complements of each

Terrence McGarty; Thomas Warner

1977-01-01

182

Galilean satellites of jupiter: 12.6-centimeter radar observations.  

PubMed

Observations of the Galilean satellites with the radar system at the Arecibo Observatory, Puerto Rico, show that their surfaces are highly diffuse scatterers of radio waves of length 12.6 centimeters; spectra of the radar echoes are asymmetric and broad. The geometric radar albedos for the outer three satellites-0.42 +/- 0.10, 0.20 +/- 0.05, and 0.09 +/- 0.02 for Europa, Ganymede, and Callisto, respectively-show about the same relative decreases as do the optical albedos, although the latter presumably bear only on material much nearer the surface. Radii of 1420 +/- 30, 2640 +/- 80, and 2360 +/- 70 kilometers for Europa, Ganymede, and Callisto were determined from the radar data and are in good agreement with the corresponding optically derived values. Io, observed successfully only once, appears to have an albedo comparable to Ganymede's, but no radius was estimated for it. PMID:17760059

Campbell, D B; Chandler, J F; Pettengill, G H; Shapiro, I I

1977-05-01

183

Advanced Land Observing Satellite (ALOS): enabling technologies and platform performance  

Microsoft Academic Search

The Advanced Land Observing Satellite (ALOS) was launched on January 24, 2006. Since then, it has been operated successfully on orbit, delivering a variety of high-resolution images in numerous quantities and contributing to disaster management support many times. ALOS is a JAXA's flagship for high-resolution Earth observation. It is the Earth observation satellite that is capable of attaining conflicting goals:

Takanori Iwata; Haruyuki Ishida; Yuji Osawa

2008-01-01

184

Cassini UVIS Observations of Saturn's Icy Satellites  

NASA Astrophysics Data System (ADS)

Over the past year Cassini's UltraViolet Imaging Spectrograph (UVIS) has obtained numerous observations of Saturn's icy satellites at far (110 to 190 nm) and extreme (55 to 110 nm) ultraviolet wavelengths. This region of the spectrum is sensitive to the presence of water, CO2 and NH3 ice and a variety of gases. Saturn's icy moons experience a different radiation and dust environments ranging from distant Phoebe in the solar wind to Enceladus at the peak of the E ring to Mimas deep in Saturn's magnetosphere. The composition of Enceladus' atmosphere (detected by the Cassini Magnetometer team) may be determined by an occultation of gamma Orionis on July 14. The UVIS spectrum of the star will be compared before and after the occultation to look for the absorption signature of atomic and molecular oxygen, carbon monoxide and atomic nitrogen. If none of these species are detected we can set upper limits on the amount of these gases in Enceladus' atmosphere. A similar technique applied to the occultation of lambda Scorpius in March allowed us to compute an upper limit for the presence of molecular oxygen of 5 x 107 molecules O2/cm3. Gamma Orionis is substantially brighter at FUV wavelengths than lambda Scorpius, and the UVIS will be configured for full spectral resolution, so we anticipate more sensitive detection thresholds. We will also present comparative results for the composition of the surfaces (distribution of water ice on Phoebe is heterogeneous, the bright side of Iapetus is more similar to Phoebe than the dark side), predominant grain size of ice on surfaces dominated by water ice, and general uv albedo. These data sets will eventually allow comparison of the efficacy of processes that affect the uppermost surface. This work was partially supported by JPL, California Institute of Technology, under a contract with NASA.

Hansen, C. J.; Hendrix, A. R.

2005-08-01

185

The investigation of tethered satellite system dynamics  

NASA Technical Reports Server (NTRS)

Tethered satellite system (TSS) dynamics were studied. The dynamic response of the TSS during the entire stationkeeping phase for the first electrodynamic mission was investigated. An out of plane swing amplitude and the tether's bowing were observed. The dynamics of the slack tether was studied and computer code, SLACK2, was improved both in capabilities and computational speed. Speed hazard related to tether breakage or plasma contactor failure was examined. Preliminary values of the potential difference after the failure and of the drop of the electric field along the tether axis have been computed. The update of the satellite rotational dynamics model is initiated.

Lorenzini, E.

1984-01-01

186

Observe animated satellite images of water vapor  

NSDL National Science Digital Library

This Flash animation points out water vapor content 6-10 km above Earth's surface measured by infrared sensors on satellites. Lighter areas represent high moisture content, darker areas, little water vapor. Jet streams are viewed as elongated dark regions bordered by lighter sections.

Goes; Noaa; Earth, Exploring

187

Atmospheric Tides and Earth Satellite Observations  

Microsoft Academic Search

G. V. GROVES, in a recent communication1, offered an explanation of the marked change in slope of the periodic time curves of the satellites 1958 beta, 1958 delta 1 and delta 2. His suggestion of a relatively sharp discontinuity in atmospheric density on passing from the dark to the light side of the Earth is, however, at variance with the

D. G. Parkyn

1959-01-01

188

Observations of the Climate System  

NASA Technical Reports Server (NTRS)

Observations of the climate system are critical for model validation and initialization, and also for monitoring in case of "surprises." Presently. we are still benefiting from data provided by the international fleet of Earth Observing satellites launched from the late 1990's onwards as well as from the longer-term record provided hy the operational meteorological satellites. However, we could be facing some data gaps in the near term in some critical areas. In situ measurements continue to be vital and, while they may be augmented hy future satellite measurements, will continue to be irreplaceable.

Sellers, Piers J.

2012-01-01

189

Observations of artificial satellites of Earth and natural satellites of Jupiter in Crimean Laboratory of SAI  

NASA Astrophysics Data System (ADS)

In the report possibilities of the telescope RST-220 (diameter of the mirror 22cm) for the solution of various observation tasks are shown. Since 2008 this tool has been used for regular high-precision astrometric observations of geostationary satellites within cooperation of observations according to the ISON program. In addition to astrometric observations photometric observations have been made as well. In 2009 the worldwide campaign on photometric observations of mutual occultations and eclipses of Galilean satellites of Jupiter was founded. Using RST-220 it was managed to obtain some light curves. The light curve of the unique double event - an occultation and an eclipse - is given for satellites Io and Europe.

Irsmambetova, T. R.; Borisova, N. N.; Borisov, G. V.; Bagaev, L. A.; Agapov, V. M.; Molotov, I. E.

2014-03-01

190

Satellite Observed Changes in the Arctic  

NASA Technical Reports Server (NTRS)

The Arctic is currently considered an area in transformation. Glaciers have been retreating, permafrost has been diminishing, snow covered areas have been decreasing, and sea ice and ice sheets have been thinning. This paper provides an overview of the unique role that satellite sensors have contributed in the detection of changes in the Arctic and demonstrates that many of the changes are not just local but a pan-Arctic phenomenon. Changes from the upper atmosphere to the surface are discussed and it is apparent that the magnitude of the trends tends to vary from region to region and from season to season. Previous reports of a warming Arctic and a retreating perennial ice cover have also been updated, and results show that changes are ongoing. Feedback effects that can lead to amplification of the signals and the role of satellite data in enhancing global circulation models are also discussed.

Comiso, Josefino C.; Parkinson, Claire L.

2004-01-01

191

The Nimbus satellites - Pioneering earth observers  

SciTech Connect

The many scientific achievements of the Nimbus series of seven satellites for low-altitude atmospheric research and global weather surveillance are reviewed. The series provides information on fishery resources, weather modeling, atmospheric pollution monitoring, earth's radiation budget, ozone monitoring, ocean dynamics, and the effects of cloudiness. Data produced by the forty-eight instruments and sensors flown on the satellites are applied in the fields of oceanography, hydrology, geology, geomorphology, geography, cartography, agriculture and meteorology. The instruments include the Coastal Zone Color Scanner (which depicts phytoplankton concentrations in coastal areas), the Scanning Multichannel Microwave Radiometer (which measures sea-surface temperatures and sea-surface wind-speed), and the Total Ozone Mapping Spectrometer (which provides information on total amounts of ozone in the earth's atmosphere).

White, C. (NASA, Goddard Space Flight Center, Greenbelt, MD (USA))

1990-11-01

192

The Nimbus satellites - Pioneering earth observers  

NASA Technical Reports Server (NTRS)

The many scientific achievements of the Nimbus series of seven satellites for low-altitude atmospheric research and global weather surveillance are reviewed. The series provides information on fishery resources, weather modeling, atmospheric pollution monitoring, earth's radiation budget, ozone monitoring, ocean dynamics, and the effects of cloudiness. Data produced by the forty-eight instruments and sensors flown on the satellites are applied in the fields of oceanography, hydrology, geology, geomorphology, geography, cartography, agriculture and meteorology. The instruments include the Coastal Zone Color Scanner (which depicts phytoplankton concentrations in coastal areas), the Scanning Multichannel Microwave Radiometer (which measures sea-surface temperatures and sea-surface wind-speed), and the Total Ozone Mapping Spectrometer (which provides information on total amounts of ozone in the earth's atmosphere).

White, Carolynne

1990-01-01

193

Satellite Atmosphere and Io Torus Observations  

NASA Technical Reports Server (NTRS)

Io is the most volcanically active body in the solar system, and it is embedded deep within the strongest magnetosphere of any planet. This combination of circumstances leads to a host of scientifically compelling phenomena, including (1) an atmosphere out of proportion with such a small object, (2) a correspondingly large atmospheric escape rate, (3) a ring of dense plasma locked in a feedback loop with the atmosphere, and (4) a host of Io-induced emissions from radio bursts to UV auroral spots on Jupiter. This proposal seeks to continue our investigation into the physics connecting these phenomena, with emphasis on Io's atmosphere and plasma torus. The physical processes are clearly of interest for Io, and also other places in the solar system where they are important but not readily observable.

Schneider, Nicholas M.

2000-01-01

194

Satellite observations of Mt. St. Helens  

Microsoft Academic Search

The major eruption of Mt. St. Helens on May 18, 1980, was recorded by infrared sensors aboard two U.S. Air Force satellites. The extent of the coverage and the completeness of the data base appear to be unique, providing information unavailable from other sources. The eruption was monitored essentially continuously, beginning at 15:32:57 UT, less than 1 min after the

D. J. Rice; D. K. Watson

1981-01-01

195

The observational environment of astronomical satellites and related software subroutines  

NASA Technical Reports Server (NTRS)

Methods are described for calculating significant factors in the observational environment of orbiting astronomical satellites. These factors must be considered in the process of scheduling observations and in data reduction. Subroutines which perform these calculations are described.

West, D. K.; Greville, E. M.

1972-01-01

196

Observations of iodine monoxide columns from satellite  

NASA Astrophysics Data System (ADS)

Iodine species in the troposphere are linked to ozone depletion and new particle formation. In this study, a full year of iodine monoxide (IO) columns retrieved from measurements of the SCIAMACHY satellite instrument is presented, coupled with a discussion of their uncertainties and the detection limits. The largest amounts of IO are found near springtime in the Antarctic. A seasonal variation of iodine monoxide in Antarctica is revealed with high values in springtime, slightly less IO in the summer period and again larger amounts in autumn. In winter, no elevated IO levels are found in the areas accessible to satellite measurements. This seasonal cycle is in good agreement with recent ground-based measurements in Antarctica. In the Arctic region, no elevated IO levels were found in the period analysed. This implies that different conditions with respect to iodine release exist in the two Polar Regions. To investigate possible release mechanisms, comparisons of IO columns with those of tropospheric BrO, and ice coverage are described and discussed. Some parallels and interesting differences between IO and BrO temporal and spatial distributions are identified. Overall, the large spatial coverage of satellite retrieved IO data and the availability of a long-term dataset provide new insight about the abundances and distributions of iodine compounds in the troposphere.

Schönhardt, A.; Richter, A.; Wittrock, F.; Kirk, H.; Oetjen, H.; Roscoe, H. K.; Burrows, J. P.

2008-02-01

197

Automated satellite telemetry processing system  

NASA Astrophysics Data System (ADS)

In this paper we describe the design and important implementation details of the new automated system for processing satellite telemetry developedat Skobeltsyn Institute of Nuclear Physics of Moscow State University (SINP MSU) . We discuss the most common tasks and pitfall for such systems built around data stream from a single spacecraft or a single instrument, and suggest a solution that allows to quickly develop telemetry processing modules and to integrate them with an existing polling mechanism, support infrastructure and data storage in Oracle or MySQL database systems. We also demonstrate the benefits of this approach using modules for processing three different spacecraft data streams: Coronas-Photon (2009-003A), Tatiana-2 (2009-049D) and Meteor-M no.1 (2009-049A). The data format and protocols used by each of these spacecraft have distinct peculiarities, which nevertheless did not pose a problem for integrating their modules into the main system. Remote access via web interface to Oracle databases and sophisticated visualization tools create a possibility of efficient scientific exploitation of satellite data. Such a system is already deployed at the web portal of the Space Monitoring Data Center (SMDC) of SINP MSU (http://smdc.sinp.msu.ru).

Parunakian, David; Kalegaev, Vladimir; Barinova, Vera

198

Gravity gradiometry from the Tethered Satellite System  

NASA Technical Reports Server (NTRS)

Measurement of the gradient of the gravitational acceleration from a satellite platform is likely to provide the next improvement in knowledge of the earth's gravity field after the upcoming Geopotential Research Mission (GRM). Observations from the subsatellite of a Tethered Satellite System (TSS) would increase sensitivity and resolution due to the low altitude possible. However, the TSS is a dynamically 'noisy' system and would be perturbed by atmospheric drag fluctuations. The dynamic noise is being modeled in order to evaluate the feasibility of TSS gradiometry and to design methods of abating the error caused by this noise. The demonstration flights of the TSS will provide an opportunity to directly observe the dynamical environment and refine modeling techniques.

Gullahorn, G. E.; Grossi, M. D.; Fuligni, F.

1985-01-01

199

Astrographic observations of the major Uranian satellites from Voyager 2  

NASA Astrophysics Data System (ADS)

This article provides the reduced astrographic observations of the major Uranian satellites derived from star-satellite imaging data acquired by the Voyager 2 spacecraft. The data set contains 445 sets of spacecraft-centered right ascension and declination observations and includes all of the observations used in Voyager encounter operations. The conversion process from imaging to astrographic observations was identical to that used for the Neptunian satellites (Jacobson 1991). The effect of using the astrographic rather than imaging form in ephemeris improvement is evaluated.

Jacobson, R. A.

1992-12-01

200

Studies of the major planet satellite systems  

NASA Technical Reports Server (NTRS)

A summary is presented of the available data on the satellites of the major planets, including the currently most plausible models for several observed phenomena, for the planning of spacecraft missions to these objects. Some of the important questions likely to be solved by flyby and/or orbital missions to the giant planets are detailed, the importance of these studies to our understanding of the solar system as a whole is indicated.

Frey, H.; Lowman, P. D.

1974-01-01

201

Astrometry in the Uranian system of satellites  

NASA Astrophysics Data System (ADS)

The predicted occultation between the satellites Miranda(UV) and Oberon(UIV) was observed on July 30, 2007 using SpeX/IRTF system and CODAM-Paris Observatory facility. Data analysis reveals that the predicted magnitude drop for this phenomenon was overestimated and we establish an upper limit of 0m.05 for the phenomenon, perhaps due to a non-lambertian limb scattering. The astrometry obtained from this run reveals good agreement with the LA06 numerical model.

Birlan, Mirel; Nedelcu, Dan Alin

2008-09-01

202

Co-ordination of satellite and data programs: The committee on earth observation satellites' approach  

NASA Astrophysics Data System (ADS)

Every year, an average of eight new civilian remote sensing satellite missions are launched. Cumulatively, over 250 such missions, each with a cost equivalent in current value to between US 100 million to US 1000 million, have been sponsored by space agencies in perhaps two dozen countries. These missions produce data and information products which are vital for informed decision making all over the world, on matters relating to natural resource exploitation, health and safety, sustainable national development, infrastructure planning, and a host of other applications. By contributing to better scientific understanding of global changes in the atmosphere, land surface, oceans and ice caps, these silently orbiting sentinels in the sky make it possible for governments and industries to make wiser environmental policy decisions and support the economic development needs of humanity. The international Committee on Earth Observation Satellites (CEOS) is the premier world body for co-ordinating and planning civilian satellite missions for Earth observation. Through its technical working groups and special task teams, it endeavours to: • maximise the international benefits from Earth observation satellites; and • harmonise practice in calibration, validation, data management and information systems for Earth observation. CEOS encompasses not only space agencies (data providers), but also the great international scientific and operational programs which rely on Earth science data from space. The user organisations affiliated with CEOS, together with the mission operators, attempt to reconcile user needs with the complex set of considerations — including national interests, cost, schedule — which affect the undertaking of space missions. Without such an internationally co-ordinated consensual approach, there is a much greater risk of waste through duplication, and of missed opportunity, or through the absence of measurements of some vital physical or biological parameter by space borne sensors. Mechanisms used by CEOS to carry out these tasks are built upon consensus and understanding, as well as on technology transfer between countries. An area of recent heightened endeavour in CEOS has been to determine and address the special needs of developing countries in respect of Earth observation data. In the next several years, a new wave of Earth observation will break, as the private sector, revitalised with decommissioned military technology, brings exciting new capabilities to international remote sensing. With rapidly burgeoning markets in spatial information or geomatics, as well as the continuing thirst of science programs for spatial information, there is a challenge upon the international space community to reassess continually, the most expedient and socially constructive means of making available in a fair and open way, geographically-reference information obtained with space observation systems.

Embleton, B. J. J.; Kingwell, J.

1997-01-01

203

Tethered Satellite System Contingency Investigation Board  

NASA Technical Reports Server (NTRS)

The Tethered Satellite System (TSS-1) was launched aboard the Space Shuttle Atlantis (STS-46) on July 31, 1992. During the attempted on-orbit operations, the Tethered Satellite System failed to deploy successfully beyond 256 meters. The satellite was retrieved successfully and was returned on August 6, 1992. The National Aeronautics and Space Administration (NASA) Associate Administrator for Space Flight formed the Tethered Satellite System (TSS-1) Contingency Investigation Board on August 12, 1992. The TSS-1 Contingency Investigation Board was asked to review the anomalies which occurred, to determine the probable cause, and to recommend corrective measures to prevent recurrence. The board was supported by the TSS Systems Working group as identified in MSFC-TSS-11-90, 'Tethered Satellite System (TSS) Contingency Plan'. The board identified five anomalies for investigation: initial failure to retract the U2 umbilical; initial failure to flyaway; unplanned tether deployment stop at 179 meters; unplanned tether deployment stop at 256 meters; and failure to move tether in either direction at 224 meters. Initial observations of the returned flight hardware revealed evidence of mechanical interference by a bolt with the level wind mechanism travel as well as a helical shaped wrap of tether which indicated that the tether had been unwound from the reel beyond the travel by the level wind mechanism. Examination of the detailed mission events from flight data and mission logs related to the initial failure to flyaway and the failure to move in either direction at 224 meters, together with known preflight concerns regarding slack tether, focused the assessment of these anomalies on the upper tether control mechanism. After the second meeting, the board requested the working group to complete and validate a detailed integrated mission sequence to focus the fault tree analysis on a stuck U2 umbilical, level wind mechanical interference, and slack tether in upper tether control mechanism and to prepare a detailed plan for hardware inspection, test, and analysis including any appropriate hardware disassembly.

1992-01-01

204

Assessment of Global Annual Atmospheric Energy Balance from Satellite Observations  

NASA Technical Reports Server (NTRS)

Global atmospheric energy balance is one of the fundamental processes for the earth's climate system. This study uses currently available satellite data sets of radiative energy at the top of atmosphere (TOA) and surface and latent and sensible heat over oceans for the year 2000 to assess the global annual energy budget. Over land, surface radiation data are used to constrain assimilated results and to force the radiation, turbulent heat, and heat storage into balance due to a lack of observation-based turbulent heat flux estimations. Global annual means of the TOA net radiation obtained from both direct measurements and calculations are close to zero. The net radiative energy fluxes into the surface and the surface latent heat transported into the atmosphere are about 113 and 86 Watts per square meter, respectively. The estimated atmospheric and surface heat imbalances are about -8 9 Watts per square meter, values that are within the uncertainties of surface radiation and sea surface turbulent flux estimates and likely systematic biases in the analyzed observations. The potential significant additional absorption of solar radiation within the atmosphere suggested by previous studies does not appear to be required to balance the energy budget the spurious heat imbalances in the current data are much smaller (about half) than those obtained previously and debated at about a decade ago. Progress in surface radiation and oceanic turbulent heat flux estimations from satellite measurements significantly reduces the bias errors in the observed global energy budgets of the climate system.

Lin, Bing; Stackhouse, Paul; Minnis, Patrick; Wielicki, Bruce A.; Hu, Yongxiang; Sun, Wenbo; Fan, Tai-Fang (Alice); Hinkelman, Laura

2008-01-01

205

Satellite observations of Magnetospheric Line Radiation  

NASA Astrophysics Data System (ADS)

Results of a systematic survey of Magnetospheric Line Radiation (MLR) observed by the DEMETER spacecraft (launched in June, 2004, inclination ~98 degrees, altitude ~700 km, designed to study electromagnetic phenomena connected with seismic or man-made activity) are presented. In order to obtain a statistically significant data set, an automatic identification procedure of possible MLR events has been developed and applied to all the data measured since the beginning of the mission. We show that there are two principally different classes of events: 1) Events with frequency spacing of 50/100 or 60/120 Hz (Power Line Harmonic Radiation, PLHR). The artificial origin of these events from power systems is demonstrated by tracing magnetic field lines to the possible regions of generation. Effects of several parameters (peak intensity, magnetic local time, Kp index, number of lines, frequency) are studied. 2) Events with frequency spacing different from frequencies of power systems ("real-MLR"). Since these emissions usually occur at lower frequencies, it is in many cases possible to use ELF data, where all the 6 components of the electromagnetic field are measured during the Burst mode. We perform a detailed analysis of these events, classifying them into several groups. There is no evidence for their artificial origin.

Nemec, F.; Santolik, O.; Parrot, M.; Berthelier, J. J.

2006-12-01

206

Committee on Earth Observation Satellites (CEOS): International Directory Network (IDN)  

NSDL National Science Digital Library

The Committee on Earth Observation Satellites International Directory Network (CEOS/IDN) is an international effort developed to assist researchers in locating information on remotely sensed datasets. It provides free, on-line access to information on worldwide datasets in the Earth sciences: geoscience, satellite remote sensing; and hydrospheric, biospheric, and atmospheric sciences. Users may search datasets by topic, data category, or text search.

207

On classifying rain types using satellite microwave observations  

Microsoft Academic Search

Classification of rain type in satellite microwave observations is useful for various studies ranging from numerical weather prediction and precipitation climatology to satellite retrieval of rain amounts. In this study we have first examined the possibility of determining the distribution of convective\\/stratiform rain within a typical microwave radiometric pixel size area represented by the Tropical Rainfall Measuring Mission Microwave Imager

Atul Kumar Varma; Guosheng Liu

2010-01-01

208

Economics of satellite communications systems  

NASA Astrophysics Data System (ADS)

This paper is partly a tutorial, telling systematically how one goes about calculating the total annual costs of a satellite communications system, and partly the expression of some original ideas on the choice of parameters so as to minimize these costs. The calculation of costs can be divided into two broad categories. The first is technical and is concerned with estimating what particular equipment will cost and what will be the annual expense to maintain and operate it. One starts in the estimation of any new system by listing the principal items of equipment, such as satellites, earth stations of various sizes and functions, telemetry and tracking equipment and terrestrial interfaces, and then estimating how much each item will cost. Methods are presented for generating such estimates, based on a knowledge of the gross parameters, such as antenna size, coverage area, transmitter power and information rate. These parameters determine the system performance and it is usually possible, knowing them, to estimate the costs of the equipment rather well. Some formulae based on regression analyses are presented. Methods are then given for estimating closely related expenses, such as maintenance and operation, and then an approximate method is developed for estimating terrestrial interconnection costs. It is pointed out that in specific cases when tariff and geographical information are available, it is usually better to work with specific data, but nonetheless it is often desirable, especially in global system estimating, to approximate these interconnect costs without recourse to individual tariffs. The procedure results in a set of costs for the purchase of equipment and its maintenance, and a schedule of payments. Some payments will be incurred during the manufacture of the satellite and before any systems operation, but many will not be incurred until the system is no longer in use, e.g. incentives. In any case, with the methods presented in the first section, one arrives at a schedule of costs and payments for all the items and the years in which they will be incurred. The second category of costing problems is one of financing or engineering economics. All the costs are first "present valued" to some reference period using rates of return appropriate to the particular situation. One finally arrives at sets of annual costs which can be used as the basis for setting lease costs or revenue requirements and tariffs. The correspondence between methods using discounted rates of return and capital recovery formulae on one hand and those using various depreciation schedules, such as is typical of regulated industries on the other hand, is discussed. The remainder of the paper is devoted to discussing the relationship between critical parameters, such as replacement schedules, design lifetime, satellite power and Earth station antenna size, and the overall costs. It is shown that optima for these parameters may exist and can be calculated. In particular, the optimization of satellite replacement schedules to minimize the present value of total investment over a very long period is presented, along with simplified versions of the theory suitable for system planning. The choice of EIRP is also discussed and a procedure for choosing the value that minimizes the costs is shown.

Pritchard, Wilbur L.

209

Satellite voice broadcast system study, volume 2  

NASA Technical Reports Server (NTRS)

This study investigates the feasibility of providing Voice of America (VOA) broadcasts by satellite relay, rather than via terrestrial relay stations. Satellite voice broadcast systems are described for three different frequency bands: HF (26 MHz), VHF (68 MHz), and L-band (1.5 GHz). The geographical areas of interest at HF and L-band include all major land masses worldwide with the exception of the U.S., Canada, and Australia. Geostationary satellite configurations are considered for both frequency bands. In addition, a system of subsynchronous, circular satellites with an orbit period of 8 hours is developed for the HF band. VHF broadcasts, which are confined to the Soviet Union, are provied by a system of Molniya satellites. Satellites intended for HF or VHF broadcastinbg are extremely large and heavy. Satellite designs presented here are limited in size and weight to the capability of the STS/Centaur launch vehicle combination. Even so, at HF it would take 47 geostationary satellites or 20 satellites in 8-hour orbits to fully satisfy the voice-channel requirements of the broadcast schedule provided by VOA. On the other hand, three Molniya satellites suffice for the geographically restricted schedule at VHF. At L-band, only four geostationary satellites are needed to meet the requirements of the complete broadcast schedule. Moreover, these satellites are comparable in size and weight to current satellites designed for direct broadcast of video program material.

Horstein, M.

1985-01-01

210

Satellite voice broadcast system study, volume 2  

NASA Astrophysics Data System (ADS)

This study investigates the feasibility of providing Voice of America (VOA) broadcasts by satellite relay, rather than via terrestrial relay stations. Satellite voice broadcast systems are described for three different frequency bands: HF (26 MHz), VHF (68 MHz), and L-band (1.5 GHz). The geographical areas of interest at HF and L-band include all major land masses worldwide with the exception of the U.S., Canada, and Australia. Geostationary satellite configurations are considered for both frequency bands. In addition, a system of subsynchronous, circular satellites with an orbit period of 8 hours is developed for the HF band. VHF broadcasts, which are confined to the Soviet Union, are provied by a system of Molniya satellites. Satellites intended for HF or VHF broadcastinbg are extremely large and heavy. Satellite designs presented here are limited in size and weight to the capability of the STS/Centaur launch vehicle combination. Even so, at HF it would take 47 geostationary satellites or 20 satellites in 8-hour orbits to fully satisfy the voice-channel requirements of the broadcast schedule provided by VOA. On the other hand, three Molniya satellites suffice for the geographically restricted schedule at VHF. At L-band, only four geostationary satellites are needed to meet the requirements of the complete broadcast schedule. Moreover, these satellites are comparable in size and weight to current satellites designed for direct broadcast of video program material.

Horstein, M.

1985-07-01

211

Assimilation of GOES satellite-based convective initiation and cloud growth observations into the Rapid Refresh and HRRR systems to improve aviation forecast guidance  

NASA Astrophysics Data System (ADS)

Latent heating profiles derived from GOES satellite-based cloud-top cooling rates are being assimilated into a retrospective version of the Rapid Refresh system (RAP) being run at the Global Systems Division. Assimilation of these data may help reduce the time lag for convection initiation (CI) in both the RAP model forecasts and in 3-km High Resolution Rapid Refresh (HRRR) model runs that are initialized off of the RAP model grids. These data may also improve both the location and organization of developing convective storm clusters, especially in the nested HRRR runs. These types of improvements are critical for providing better convective storm guidance around busy hub airports and aviation corridor routes, especially in the highly congested Ohio Valley - Northeast - Mid-Atlantic region. Additional work is focusing on assimilating GOES-R CI algorithm cloud-top cooling-based latent heating profiles directly into the HRRR model. Because of the small-scale nature of the convective phenomena depicted in the cloud-top cooling rate data (on the order of 1-4 km scale), direct assimilation of these data in the HRRR may be more effective than assimilation in the RAP. The RAP is an hourly assimilation system developed at NOAA/ESRL and was implemented at NCEP as a NOAA operational model in May 2012. The 3-km HRRR runs hourly out to 15 hours as a nest within the ESRL real-time experimental RAP. The RAP and HRRR both use the WRF ARW model core, and the Gridpoint Statistical Interpolation (GSI) is used within an hourly cycle to assimilate a wide variety of observations (including radar data) to initialize the RAP. Within this modeling framework, the cloud-top cooling rate-based latent heating profiles are applied as prescribed heating during the diabatic forward model integration part of the RAP digital filter initialization (DFI). No digital filtering is applied on the 3-km HRRR grid, but similar forward model integration with prescribed heating is used to assimilate information from radar reflectivity, lightning flash density and the satellite based cloud-top cooling rate data. In the current HRRR configuration, 4 15-min cycles of latent heating are applied during a pre-forecast hour of integration. This is followed by a final application of GSI at 3-km to fit the latest conventional observation data. At the conference, results from a 5-day retrospective period (July 5-10, 2012) will be shown, focusing on assessment of data impact for both the RAP and HRRR, as well as the sensitivity to various assimilation parameters, including assumed heating strength. Emphasis will be given to documenting the forecast impacts for aviation applications in the Eastern U.S.

Mecikalski, John; Smith, Tracy; Weygandt, Stephen

2014-05-01

212

Perl Tools for Automating Satellite Ground Systems  

NASA Technical Reports Server (NTRS)

The freeware scripting language Pert offers many opportunities for automating satellite ground systems for new satellites as well as older, in situ systems. This paper describes a toolkit that has evolved from of the experiences gained by using Pert to automate the ground system for the Compton Gamma Ray Observatory (CGRO) and for automating some of the elements in the Earth Observing System Data and Operations System (EDOS) ground system at Goddard Space Flight Center (GSFC). CGRO is an older ground system that was forced to automate because of fund cuts. Three 8 hour shifts were cut back to one 8 hour shift, 7 days per week. EDOS supports a new mission called Terra, launched December 1999 that requires distribution and tracking of mission-critical reports throughout the world. Both of these ground systems use Pert scripts to process data and display it on the Internet as well as scripts to coordinate many of the other systems that make these ground systems work as a coherent whole. Another task called Automated Multimodal Trend Analysis System (AMTAS) is looking at technology for isolation and recovery of spacecraft problems. This effort has led to prototypes that seek to evaluate various tools and technology that meet at least some of the AMTAS goals. The tools, experiences, and lessons learned by implementing these systems are described here.

McLean, David; Haar, Therese; McDonald, James

2000-01-01

213

India's domestic satellite communication system - INSAT  

NASA Astrophysics Data System (ADS)

The Indian National Satellite System (INSAT-I) possesses two multipurpose satellites in geostationary orbit, each of which has twelve 36 MHz-wide C-band channels, two 36 MHz-wide S-band channels, a Very High Resolution Radiometer for earth observation in the visible and IR bands, and a 200 kHz-wide Data Relay Transponder. The ground segment of INSAT-I consists of five large earth stations, 13 medium earth stations, 10 remote area terminals, and one mobile emergency communications terminal. C-band channels are to be used for thick and thin route telephony, while S-band channels are devoted to TV broadcasts to community receivers, radio networking, and Disaster Warning System services, using low level injected carriers. Data Collection Platforms relay meteorological and hydrological data via the Data Relay Transponder to a central station.

Kibe, S. V.; Thomas, G.

214

The Use of a Parallel Data Processing and Error Analysis System (DPEAS) for the Observational Exploration of Complex Multi-Satellite Non-Gaussian Data Assimilation Algorithms  

NASA Astrophysics Data System (ADS)

The CSU/NOAA Data Processing and Error Analysis System (DPEAS) was created to merge, or blend, multiple satellite and model data sets within a single consistent framework. DPEAS is designed to be used at both research and operational facilities to facilitate Research-to-Operations technology transfers. The system supports massive parallelization via grid computing technologies, and hosts data fusion techniques for transference to 24/7 operations in a low cost computational environment. In this work, we highlight the data assimilation and data fusion methodologies of the DPEAS framework that facilitates new and complex multi-satellite non-Gaussian data assimilation algorithm developments. DPEAS is in current operational use at NOAA/NESDIS Office of Satellite and Product Operations (OSPO) and performs multi-product data fusion of global "blended" Total Precipitable Water (bTPW) and blended Rainfall Rate (bRR). In this work we highlight: 1) the current dynamic inter-satellite calibration processing performed within the DPEAS data fusion and error analysis, 2) as well as our DPEAS development plans for future blended products (AMSR-2 and Megha-Tropiques), and 3) layered TPW products using the NASA AIRS data for National Weather Service forecaster use via the NASA SPoRT facility at Huntsville, AL. We also discuss new system additions for cloud verification and prediction activities in collaboration with the National Center for Atmospheric Research (NCAR), and planned use with the USAF Air Force Weather Agency's (AFWA) global Cloud Depiction and Forecast System (CDFS) facilities. Scientifically, we focus on the data fusion of atmospheric and land surface product information, including global cloud and water vapor data sets, soil moisture data, and specialized land surface products. The data fusion methods include the use of 1DVAR data assimilation for satellite sounding data sets, and numerous real-time statistical analysis methods. Our new development activities to extend the current 1DVAR algorithm to use and test a new non-Gaussian data assimilation method are presented. This research was supported by multiple grants from the NOAA/NESDIS Product System Development and Implementation (PSDI) program, a NASA ROSES grant, and a grant by the Air Force Weather Agency (AFWA) to the DoD Center for Geosciences / Atmospheric Research (CG/AR) at Colorado State University, as well as a subcontract from the National Center for Atmospheric Research (NCAR) to CSU.

Jones, A. S.; Fletcher, S. J.; Kidder, S. Q.; Forsythe, J. M.

2012-12-01

215

Observations of orbital debris and satellites in Slovak Republic  

NASA Astrophysics Data System (ADS)

There are many accidental optically tracked artificial objects during observations at Astronom-ical and Geophysical Observatory FMPI CU, Modra, Slovak Republic (AGO). Those objects are usually orbital debris or satellites. A tool to identify such a type of objects was necessary to create. Our software is called SatEph and is used to identify tracked artificial objects and to compute their orbital elements. SatEph is based on analytic propagation model SGP4 and TLE data. Program is still under development and in the near future it will be a part of software for automated search telescope for small near Earth asteroids at AGO. We present orbital debris observation simulation for the new optical searching system. Unlike other aster-oids searching systems (Catalina Sky Survey, LINEAR, Spacewatch etc.) our system should be capable to detect small asteroids in close vicinity of the Earth (smaller then Lunar distance) with high angular speed. The limiting magnitude of observable objects is about +16 magnitude and the pixel scale is 4,6 arcsec/px. This allows us to detect man made objects as well. We studied how many satellites and orbital debris with known orbital elements are able to track per given observing night. We also studied frequency detection of tracked object during one night. The searching system field of view will be 4.4 x 4.4 square degrees and the system will search more then 2000 square degrees per night. Exposure time for every single CCD shot is set to 30 seconds. We found out, there is possible to track from 250 to 450 objects (mostly with geosynchronous orbits) per one night in dependence on given day of the year. More then 200 objects have at least 3 astrometric positions per one night, which can be useful for orbit determination process. The tracked objects are mostly satellites and rocket bodies, which have different orbits, from low Earth orbit to geosynchronous Earth orbit. Data of orbital debris astrometric positions will be offered for national space agencies and used for our own orbit determination. Those data could be useful for orbital elements updating of catalogue, or non catalogue artificial objects.

Silha, Jiri; Toth, Juraj

216

Applications systems verification and transfer project. Volume 6: Operational applications of satellite snow-cover observations NOAA/NESS support study  

NASA Technical Reports Server (NTRS)

Geostationary and polar orbiting satellite data from the National Oceanic and Atmospheric Administration were used to operationally provide field hydrologists with basin snowcover percentages for inclusion in runoff models. Data reduction is accomplished thru the use of optical rectification devices and electronic color density slicers. Over two thousand satellite-derived snow maps covering 30 different basins in the western United States were provided to users. Plans for improving snowmapping techniques on computer interactive systems and by all-digital analysis are presented. A description of the newest generation of NOAA polar orbiters, TIROS-N, and its potential for snowmapping is reviewed. Snowcover percentages for all basins determined between November 1974 and July 1978 are presented in tabular format.

Schneider, S. R.

1981-01-01

217

Tethered satellite system dynamics and control  

NASA Technical Reports Server (NTRS)

The first tethered satellite system, scheduled for launch in May 1991, is reviewed. The system dynamics, dynamics control, and dynamics simulations are discussed. Particular attention is given to in-plane and out-of-plane librations; tether oscillation modes; orbiter and sub-satellite dynamics; deployer control system; the sub-satellite attitude measurement and control system; the Aeritalia Dynamics Model; the Martin-Marietta and NASA-MSFC Dynamics Model; and simulation results.

Musetti, B.; Cibrario, B.; Bussolino, L.; Bodley, C. S.; Flanders, H. A.; Mowery, D. K.; Tomlin, D. D.

1990-01-01

218

Characterizing user requirements for future land observing satellites  

NASA Technical Reports Server (NTRS)

The objective procedure was developed for identifying probable sensor and mission characteristics for an operational satellite land observing system. Requirements were systematically compiled, quantified and scored by type of use, from surveys of federal, state, local and private communities. Incremental percent increases in expected value of data were estimated for critical system improvements. Comparisons with costs permitted selection of a probable sensor system, from a set of 11 options, with the following characteristics: 30 meter spatial resolution in 5 bands and 15 meters in 1 band, spectral bands nominally at Thematic Mapper (TM) bands 1 through 6 positions, and 2 day data turn around for receipt of imagery. Improvements are suggested for both the form of questions and the procedures for analysis of future surveys in order to provide a more quantitatively precise definition of sensor and mission requirements.

Barker, J. L.; Cressy, P. J.; Schnetzler, C. C.; Salomonson, V. V.

1981-01-01

219

Satellite observations of transient radio impulses from thunderstorms  

Microsoft Academic Search

Transient radio emissions from thunderstorms detected by satellites were first reported in 1995. The nature and source of these emissions remained a mystery until the launch of the FORTE satellite in 1997. FORTE, with its more sophisticated triggering and larger memory capacity showed that these emissions were connected to major thunderstorm systems. The analysis reported here, connecting FORTE RF events

P. E. Argo; M. Kirkland; A. Jacobson; R. Massey; D. Suszynsky; K. Eack; T. J. Fitzgerald; D. Smith

1999-01-01

220

Environmental objectives for the Russian American Observational Satellites (RAMOS)  

Microsoft Academic Search

The RAMOS program embodies a new direction for cooperative space-based cooperative research and development between the Russian Federation and the United States. The planned system configuration is a constellation of two satellite constellation orbiting in approximately in the same plane and at an altitude of about 500 km. These satellites, equipped with passive electro-optical sensors operating from infrared (IR) to

Thomas Humpherys; Robert Anderson; Alvin T. Stair Jr.; Ilya Schiller; Valery Sinelshchikov; V. Abramov; Victor Misnik

2003-01-01

221

Globally Gridded Satellite (GridSat) Observations for Climate Studies.  

National Technical Information Service (NTIS)

Geostationary satellites have provided routine, high temporal resolution Earth observations since the 1970s. Despite the long period of record, use of these data in climate studies has been limited for numerous reasons, among them: there is no central arc...

A. Loew C. Funk C. C. Hennon C. D. Holmes C. L. Bain C. N. Helms G. Magnusdottir G. J. Huffman H. T. Lee J. P. Kossin K. R. Knapp M. A. Bourassa M. J. Dickinson S. Ansari

2012-01-01

222

Analysis of Observations of the Middle Atmosphere from Satellites.  

National Technical Information Service (NTIS)

Satellite data are being used to investigate problems in middle atmosphere chemistry and dynamics. Efforts have been focused primarily on studies to determine the quality of observed distributions of trace species and derived dynamical quantities. Those d...

E. E. Remsberg J. M. Russell W. L. Grose T. Miles L. L. Gordley

1990-01-01

223

Improving UK Air Quality Modelling Through Exploitation of Satellite Observations  

NASA Astrophysics Data System (ADS)

In this work the applicability of satellite observations to evaluate the operational UK Met Office Air Quality in the Unified Model (AQUM) have been investigated. The main focus involved the AQUM validation against satellite observations, investigation of satellite retrieval error types and of synoptic meteorological-atmospheric chemistry relationships simulated/seen by the AQUM/satellite. The AQUM is a short range forecast model of atmospheric chemistry and aerosols up to 5 days. It has been designed to predict potentially hazardous air pollution events, e.g. high concentrations of surface ozone. The AQUM has only been validated against UK atmospheric chemistry recording surface stations. Therefore, satellite observations of atmospheric chemistry have been used to further validate the model, taking advantage of better satellite spatial coverage. Observations of summer and winter 2006 tropospheric column NO2 from both OMI and SCIAMACHY show that the AQUM generally compares well with the observations. However, in northern England positive biases (AQUM - satellite) suggest that the AQUM overestimates column NO2; we present results of sensitivity experiments on UK emissions datasets suspected to be the cause. In winter, the AQUM over predicts background column NO2 when compared to both satellite instruments. We hypothesise that the cause is the AQUM winter night-time chemistry, where the NO2 sinks are not substantially defined. Satellite data are prone to errors/uncertainty such as random, systematic and smoothing errors. We have investigated these error types and developed an algorithm to calculate and reduce the random error component of DOAS NO2 retrievals, giving more robust seasonal satellite composites. The Lamb Weather Types (LWT), an objective method of classifying the daily synoptic weather over the UK, were used to create composite satellite maps of column NO2 under different synoptic conditions. Under cyclonic conditions, satellite observed UK column NO2 is reduced as the indicative south-westerly flow transports it away from the UK over the North Sea. However, under anticyclonic conditions, the satellite shows that the stable conditions enhance the build-up of column NO2 over source regions. The influence of wind direction on column NO2 can also be seen from space with transport leeward of the source regions.

Pope, Richard; Chipperfield, Martyn; Savage, Nick

2014-05-01

224

ECC Ozonesonde Calibration and Observations: Satellite Validation  

NASA Technical Reports Server (NTRS)

The reliability of the Electrochemical Concentration Cell (ECC) ozonesonde depends on the care exercised in preparing the instrument for use. Although the ECC can be quickly prepared and flown, generally within less then one day if necessary, it is best to prepare the instrument at least one week prior to use, and as our tests have confirmed even 2-3 weeks prior to use may actually be better. There are a number of factors that must be considered when preparing an ECC. These basically are the pump efficiency, volumetric flow rate, temperature of the air entering the pump, and the background current. Also of importance is the concentration of the potassium iodide solution. Tests conducted at Wallops Island (38 N) has enabled us to identify potential problem areas and ways to avoid them. The calibration and pre-flight preparation methods will be discussed. The method of calibrating the ECC also is used at Ascension Island (8 S) and Natal, Brazil (5 S). Comparisons between vertical profiles of the ECC instrument and satellites will be reviewed as well as comparison with ground based instruments, such as, the Dobson Spectrophotometer and hand held Microtops photometers.

Schmidlin, Francis J.; Zukor, Dorothy (Technical Monitor)

2001-01-01

225

STABILITY OF SATELLITES IN CLOSELY PACKED PLANETARY SYSTEMS  

SciTech Connect

We perform numerical integrations of four-body (star, planet, planet, satellite) systems to investigate the stability of satellites in planetary systems with tightly packed inner planets (STIPs). We find that the majority of closely spaced stable two-planet systems can stably support satellites across a range of parameter-space which is only slightly decreased compared to that seen for the single-planet case. In particular, circular prograde satellites remain stable out to ?0.4 R{sub H} (where R{sub H} is the Hill radius) as opposed to 0.5 R{sub H} in the single-planet case. A similarly small restriction in the stable parameter-space for retrograde satellites is observed, where planetary close approaches in the range 2.5-4.5 mutual Hill radii destabilize most satellites orbits only if a ? 0.65 R{sub H} . In very close planetary pairs (e.g., the 12:11 resonance) the addition of a satellite frequently destabilizes the entire system, causing extreme close approaches and the loss of satellites over a range of circumplanetary semi-major axes. The majority of systems investigated stably harbored satellites over a wide parameter-space, suggesting that STIPs can generally offer a dynamically stable home for satellites, albeit with a slightly smaller stable parameter-space than the single-planet case. As we demonstrate that multi-planet systems are not a priori poor candidates for hosting satellites, future measurements of satellite occurrence rates in multi-planet systems versus single-planet systems could be used to constrain either satellite formation or past periods of strong dynamical interaction between planets.

Payne, Matthew J.; Holman, Matthew J. [Institute for Theory and Computation, Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, MS 51, Cambridge, MA 02138 (United States)] [Institute for Theory and Computation, Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, MS 51, Cambridge, MA 02138 (United States); Deck, Katherine M. [Department of Physics and Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 (United States)] [Department of Physics and Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 (United States); Perets, Hagai B., E-mail: matthewjohnpayne@gmail.com [Technion-Israel Institute of Technology, Haifa 32000 (Israel)

2013-10-01

226

Stability of Satellites in Closely Packed Planetary Systems  

NASA Astrophysics Data System (ADS)

We perform numerical integrations of four-body (star, planet, planet, satellite) systems to investigate the stability of satellites in planetary systems with tightly packed inner planets (STIPs). We find that the majority of closely spaced stable two-planet systems can stably support satellites across a range of parameter-space which is only slightly decreased compared to that seen for the single-planet case. In particular, circular prograde satellites remain stable out to ~0.4 RH (where RH is the Hill radius) as opposed to 0.5 RH in the single-planet case. A similarly small restriction in the stable parameter-space for retrograde satellites is observed, where planetary close approaches in the range 2.5-4.5 mutual Hill radii destabilize most satellites orbits only if a ~ 0.65 RH . In very close planetary pairs (e.g., the 12:11 resonance) the addition of a satellite frequently destabilizes the entire system, causing extreme close approaches and the loss of satellites over a range of circumplanetary semi-major axes. The majority of systems investigated stably harbored satellites over a wide parameter-space, suggesting that STIPs can generally offer a dynamically stable home for satellites, albeit with a slightly smaller stable parameter-space than the single-planet case. As we demonstrate that multi-planet systems are not a priori poor candidates for hosting satellites, future measurements of satellite occurrence rates in multi-planet systems versus single-planet systems could be used to constrain either satellite formation or past periods of strong dynamical interaction between planets.

Payne, Matthew J.; Deck, Katherine M.; Holman, Matthew J.; Perets, Hagai B.

2013-10-01

227

Precise station positions from VLBI observations to satellites: a simulation study  

NASA Astrophysics Data System (ADS)

Very long baseline interferometry (VLBI) tracking of satellites is a topic of increasing interest for the establishment of space ties. This shall strengthen the connection of the various space geodetic techniques that contribute to the International Terrestrial Reference Frame. The concept of observing near-Earth satellites demands research on possible observing strategies. In this paper, we introduce this concept and discuss its possible benefits for improving future realizations of the International Terrestrial Reference System. Using simulated observations, we develop possible observing strategies that allow the determination of radio telescope positions in the satellite system on Earth with accuracies of a few millimeters up to 1-2 cm for weekly station coordinates. This is shown for satellites with orbital heights between 2,000 and 6,000 km, observed by dense regional as well as by global VLBI-networks. The number of observations, as mainly determined by the satellite orbit and the observation interval, is identified as the most critical parameter that affects the expected accuracies. For observations of global positioning system satellites, we propose the combination with classical VLBI to radio sources or a multi-satellite strategy. Both approaches allow station position repeatabilities of a few millimeters for weekly solutions.

Plank, Lucia; Böhm, Johannes; Schuh, Harald

2014-03-01

228

Precise station positions from VLBI observations to satellites: a simulation study  

NASA Astrophysics Data System (ADS)

Very long baseline interferometry (VLBI) tracking of satellites is a topic of increasing interest for the establishment of space ties. This shall strengthen the connection of the various space geodetic techniques that contribute to the International Terrestrial Reference Frame. The concept of observing near-Earth satellites demands research on possible observing strategies. In this paper, we introduce this concept and discuss its possible benefits for improving future realizations of the International Terrestrial Reference System. Using simulated observations, we develop possible observing strategies that allow the determination of radio telescope positions in the satellite system on Earth with accuracies of a few millimeters up to 1-2 cm for weekly station coordinates. This is shown for satellites with orbital heights between 2,000 and 6,000 km, observed by dense regional as well as by global VLBI-networks. The number of observations, as mainly determined by the satellite orbit and the observation interval, is identified as the most critical parameter that affects the expected accuracies. For observations of global positioning system satellites, we propose the combination with classical VLBI to radio sources or a multi-satellite strategy. Both approaches allow station position repeatabilities of a few millimeters for weekly solutions.

Plank, Lucia; Böhm, Johannes; Schuh, Harald

2014-07-01

229

Japan's geostationary meteorological satellite system  

NASA Astrophysics Data System (ADS)

Equipment characteristics and missions of the Japanese geostationary meteorological satellites (GMS) are examined. GMS-1 was launched in July 1977 on a NASA Delta vehicle. GMS-2 launched from Japan, was placed into GEO in August 1981. Both spacecraft were designed for a weather watch using a visible/IR spin scan radiometer (VISSR) instrument, collection and distribution of weather data, and monitoring of solar particles. The GMS-1 unit operated on the UHF bands while the second was switched over to S-band. Solar arrays provided battery trickle-charge power with a lifetime of 5 yr. A final instrumentation component common to both spacecraft is a space environment monitor for investigating the effect of solar activity on earth communications systems.

Steggall, N.

1982-06-01

230

Observing tectonic plate motions and deformations from satellite laser ranging  

NASA Technical Reports Server (NTRS)

The scope of geodesy has been greatly affected by the advent of artificial near-earth satellites. The present paper provides a description of the results obtained from the reduction of data collected with the aid of satellite laser ranging. It is pointed out that dynamic reduction of satellite laser ranging (SLR) data provides very precise positions in three dimensions for the laser tracking network. The vertical components of the stations, through the tracking geometry provided by the global network and the accurate knowledge of orbital dynamics, are uniquely related to the center of mass of the earth. Attention is given to the observations, the methodologies for reducing satellite observations to estimate station positions, Lageos-observed tectonic plate motions, an improved temporal resolution of SLR plate motions, and the SLR vertical datum.

Christodoulidis, D. C.; Smith, D. E.; Kolenkiewicz, R.; Klosko, S. M.; Torrence, M. H.

1985-01-01

231

PSC Characteristics from Satellite Observations and Simulations  

NASA Technical Reports Server (NTRS)

POAM solar occultation observations from 1994 to present are studied for the purpose of determining Type I PSC formation characteristics and winter-long evolution. This study examines PSC observations from many years on a common basis to see if characteristics can be identified. The results show that Type Ia PSCs form at the beginning of the winter, within several days of the first drop in temperature below T_NAT, and peak early in the winter. Type Ia PSCs typically out number Ib PSCs over the winter, especially at the beginning of the winter. Type Ia and Ib PSC observations continue throughout the winter. Micro-physical models of PSC formation must match these observed characteristics. Some models predict that temperatures must be more than 5 K below T_NAT for five days before significant freezing can occur. This is not seen in the POAM observations. Differences in PSC characteristics between the first two Arctic winters (1994-1995 and 1995-1996) and later winters also suggest the influence of volcanic perturbations on PSC formation. Type Ia and Ib PSC Characteristics observed by POAM III and SAGE III for the 2002-2003 Arctic winter are compared.

Strawa, A. W.; Drdla, K.; Bokarius, K.; Fromm, M.; Alfred, J.

2004-01-01

232

The Saturnian Satellite Tethys Observed By Cassini-VIMS  

NASA Astrophysics Data System (ADS)

We present a detailed analysis of the variations in spectral properties across the surface of Saturn's satellite Tethys using Cassini/VIMS data and their relationships to geological and/or morphological characteristics as seen in the Cassini/ISS images. Despite the spectral dominance of water ice on Tethys’ surface distinct spectral variations could be detected, which are surprisingly very different from what was expected from the visible albedo derived from Voyager and Cassini camera data. The abundance of water ice usually follows the visible surface albedo as seen on many other satellites. Although on Tethys, the weakest water ice signature could be also measured on the trailing hemisphere as known from Dione and Rhea [1-3], the detailed mapping, however, shows a more complex pattern. Two relatively narrow N/S-trending bands characterized by larger ice particle sizes rather than the higher abundance of water ice separate the Saturn-facing and the anti-Saturnian hemisphere of Tethys. So far, larger ice particles could only be found in geologically young, less weathered portions of the surfaces of the icy Saturnian satellites [2,3]. On Tethys, however, the observed variations might be more complex due to the influence of fine particles from the E-ring coating the surface. In contrast to the prominent graben systems on Dione and Rhea, which show fresh ice exposed on steep walls, no spectral properties could be exclusively associated to Tethys’ extended graben system Ithaca Chasma supporting its geologically old age and that its formation was not caused by the impact event that created Odysseus [4]. References: [1] Clark, R. N., et al. (2008), Icarus, 193(2), 372-386. [2] Stephan, K., et al. (2010) Icarus, 206(2), 631-652. [3] Stephan, K. et al. (2012) PSS, 61(1), 142-160. [4] Giese et al., (2007) GRL, 34(21), L21203.

Stephan, Katrin; Jaumann, R.; Wagner, R.; Clark, R. N.; Cruikshank, D. P.; Dalle Ore, C.; Hansen, G. B.; Brown, R. H.; Giese, B.; Roatsch, T.; Matson, D.; Baines, K.; Filiacchione, G.; Cappacione, F.; Rodriguez, S.; Buratti, B. J.; Nicholson, P. D.; Sotin, C.

2012-10-01

233

Range bias in Borowiec satellite laser ranging system  

Microsoft Academic Search

The paper reports results of determination of the range bias of the satellite laser ranging system in Borowiec (7811). The range bias was determined from the observations of LAGEOS-1 and LAGEOS-2 satellites by Borowiec SLR analysis group. The results were compared with the range bias determination from four analysis centres. Significant differences in range bias, exceeding 2 cm, were found

Tomasz Celka; Stanislaw Schillak

2003-01-01

234

AW UMa observed with MOST satellite  

NASA Astrophysics Data System (ADS)

MOST observations were obtained to search for photometric non-radial oscillations; none was detected with an upper limit of 0.0001 in relative amplitude. A single, precise moment of the primary eclipse confirms the progressive shortening of the orbital period.

Rucinski, S. M.; Matthews, J. M.; Cameron, C.; Guenther, D. B.; Kuschnig, R.; Moffat, A. F. J.; Rowe, J. F.; Sasselov, D.; Weiss, W. W.

2013-11-01

235

The satellite power system concept and program  

Microsoft Academic Search

The paper summarizes the approaches that have been considered for the satellite power system (SPS) and the current reference concept defined by NASA and the Department of Energy (DOE). The overall system's characteristics are described. The NASA-DOE reference SPS system consists of two different satellite approaches, both of which utilize solar photovoltaic energy conversion and have 5-GW power outputs on

G. M. Hanley

1979-01-01

236

CEOS Committee on Earth Observations Satellites Consolidated Report, 1992  

NASA Technical Reports Server (NTRS)

A concise overview of the committee on Earth Observations Satellites (CEOS) and its Working Groups, covering the history and purpose of the Committee and its accomplishments to date are provided. The report will be updated annually before each Plenary meeting, and as developments in the Working Groups warrant. The committee on Earth Observations Satellites (originally named the International Earth Observations Satellite committee, IEOS) was treated in 1984, in response to a recommendation from the Economic Summit of Industrialized Nations Working Group on Growth, Technology, and Employment's Panel of Experts on Satellite Remote Sensing. This group recognized the multidisciplinary nature of satellite Earth observations, and the value of coordinating across all proposed missions. Thus, CEOS combined the previously existing groups for coordination on Ocean Remote-Sensing Satellites (CORSS) and coordination on Land Remote-Sensing Satellites (CLRSS), and established a broad framework for coordination across all spaceborne Earth observations missions. The first three LEOS Plenary meetings focused on treating and guiding the Working Groups deemed necessary to carry out the objectives of the CEOS members. After the third meeting, it was agreed that a more active orientation was required by the Plenary, and additional issues were brought before the group at the fourth meeting. At the fifth Plenary, international scientific programs and relevant intergovernmental organizations accepted invitations and participated as affiliate members of CEOS. This enabled progress toward integrating satellite data users' requirements into the CEOS process. Data exchange principles for global change research were also adopted. An interim CEOS Plenary meeting was held in April 1992, in preparation for the United Nations Conference on Environment and Development (UNCED). Brief encapsulations of the Plenary sessions immediately follow the Terms of Reference that govern the activities of CEOS as a whole; Terms of Reference for the individual Working Groups are included as Appendix A. A complete listing of CEOS members is offered as Appendix B.

1992-01-01

237

Providing satellite systems for the national weather satellite services.  

NASA Technical Reports Server (NTRS)

Discussion of cooperative arrangements and agreements among NASA, the Department of Commerce, and other governmental agencies in developing and operating meteorological satellite systems. The development of present interagency agreements and their conditions are discussed along with differences from the usual NASA program introduced by the supplier-client relationship between NASA and NOAA (National Oceanic and Atmospheric Administration).

Stroud, W. G.; Press, H.; Stampfl, R. A.

1973-01-01

238

Principles in Remote Sensing: Earth Observations from Satellites  

NSDL National Science Digital Library

In this self-paced, interactive tutorial, learners become familiar with basic concepts related to remote sensing of the Earth by satellites. Geosynchronous Earth Orbit (GEO) and Low Earth Orbit (LEO) satellites, as well as different types of onboard sensors, are examined for their applicability to various real-world data collection and research applications. This resource is part of the tutorial series, Satellite Observations in Science Education, and is the first of three modules in the tutorial, Principles in Remote Sensing. (Note: requires Java plug-in).

239

Global distribution of photosynthetically active radiation as observed from satellites  

NASA Technical Reports Server (NTRS)

In this study the feasibility to derive photosynthetically active radiation (PAR) on a global scale is demonstrated. In the past, information on PAR was obtained from local ground measurements in the 0.4-0.7-micron spectral interval. In the absence of such measurements, PAR was estimated from measured total solar irradiance, using empirical 'conversion factors'. It is demonstrated that this important biogeophysical parameter can now be derived from satellite observations. The inference model is implemented with global satellite data that are available from the International Satellite Cloud Climatology Project to produce for the first time global fields of PAR and corresponding 'conversion factors'.

Pinker, R. T.; Laszlo, I.

1992-01-01

240

A study of satellite emergency locator systems  

NASA Technical Reports Server (NTRS)

Satellite emergency locator systems were studied. The objective of the study was to determine the feasibility and hardware requirements for satellite systems capable of identifying and locating the position emergency locator transmitters and emergency position indicating radio beacons. Both geosynchronous and near-polar-orbiting satellites were considered. One of the most important aspects of the study was to minimize the cost of the hardware required.

1977-01-01

241

Recent state of the Aral sea from regular satellite observations.  

NASA Astrophysics Data System (ADS)

The Aral Sea disaster is one of the most significant examples of ecological catastrophe caused by mismanagement of water resources. Aral sea level dropped on 22 meters for the last 35 years. The sea separated in to two independent parts , the Large Sea(Southern) and the Small Sea (Northern), loosing more than 90% of its original water masses. After the collapse of the former Soviet Union, satellite retrieved data became the main source of information on this perishing system. Regular observations from AVHRR, SeaWiFS, MODIS and ASTER satellite sensors were used for our investigations. Sea surface temperature (SST) data of the AVHRR sensor and digital bottom map topography were used for sea level drop calculations. The Sea level defined as the digital map isobate corresponds quite well to the satellite derived coastline for the Eastern part of the Large Sea with a bottom slope of ˜ 0.00015. For the period 1989-2002 the sea level of the Large Sea dropped on 9.2 meters. However in 2003 the sea level remained stable. This stabilisation was due to an increase of water output of the rivers Amu--Darya and Syr-Darya in 2003. High resolution ASTER data showed that the main amount of Syr-Darya waters is discharged into the Large Sea. The dried bottom area now covers more than 45000 km2. On the base of AVHRR-SST data the temperature regime for different parts of the Aral Sea was calculated for the years 2002-2003. The annual amplitude of the SST variation reaches 37° C for the open waters. The observed minimum freezing point was -7° C due to very high salinity. Estimations from satellite retrieved freezing points show an increase of salinity up to 10% in the Eastern part of the Large Sea. It is almost paradox that on satellite images the ice appears warmer than the water. Strong variations of the water temperature (up to 5° C) within a few days could be observed from April to August and could be related to wind induced mixing. SeaWiFS ocean colour data were used for the investigation of the optical properties of the water in different parts of the Aral Sea for the years 2002-2003. A significant relation of optical properties with wind and temperature was obtained. Strong changes of the thermal regimes of the Sea can cause variations in local climatic conditions: The analysis of AVHRR NDVI - data for the surrounding areas demonstrated a shift in the annual vegetation cycle. In addition phenomena like: salt storms, wind driven tides, sources of groundwater, eddies and frontal structures as well as ice coverage of the Aral Sea were demonstrated on satellite images.

Stanichny, S.; Davidov, A.; Djenidi, S.; Horstmann, U.; Stanichnaya, R.; Soloviev, D.

242

Small Earth Observing Satellites Flying with Large Satellites in the A-Train  

NASA Technical Reports Server (NTRS)

This paper/poster presents a real-life example of the benefits of flying small satellites with other satellites, large or small, and vice versa. Typically, most small satellites fly payloads consisting of one or two instruments and fly in orbits that are independent from that of other satellites. The science data from these satellites are either used in isolation or correlated with instrument data from other satellites. Data correlation with other satellites is greatly improved when the measurements of the same point or air mass are taken at approximately the same time. Scientists worldwide are beginning to take advantage of the opportunities for improved data correlation, or coincidental science, offered by the international Earth Observing Constellation known as the A-Train (sometimes referred to as the Afternoon Constellation). Most of the A-Train satellites are small - the A-Train is anchored by two large NASA satellites (EOS-Aqua and EOS-Aura), but consists also of 5 small satellites (CloudSat, CALIPSO, PARASOL, OCO and Glory these last two will join in 2009). By flying in a constellation, each mission benefits from coincidental observations from instruments on the other satellites in the constellation. Essentially, from a data point of view, the A-Train can be envisioned as a single, virtual science platform with multiple instruments. Satellites in the A-Train fly at 705 km in sun-synchronous orbits. Their mean local times at the equator are within seconds to a few minutes of each other. This paper describes the challenges of operating an international constellation of independent satellites from the U.S. and Europe to maximize the coincidental science opportunities while at the same time minimizing the level of operational interactions required between team members. The A-Train mission teams have been able to demonstrate that flying as members of an international constellation does not take away the flexibility to accommodate new requirements. Specific examples will be cited, including CloudSat's relocation (to accommodate a new viewing angle for the CALIPSO satellite), Glory's replan to move closer to PARASOL, and OCO's long term plans to minimize on-orbit operations costs while maintaining safety. In all cases, safety is ensured, science returns are enhanced, and operational flexibility is retained to the maximum extent possible.

Kelly, Angelita C.; Loverro, Adam; Case, Warren F.; Queruel, Nadege; Marechal, Chistophe; Barroso, Therese

2009-01-01

243

Error analysis of earth physics satellite systems  

NASA Technical Reports Server (NTRS)

Error analysis of distant-satellite-to-close-satellite range-rate, satellite-to-sea altimetry, and ground station to satellite range are made by simulations in which observational variances are assumed, observation equations are formed, and normal equations incremented. The final normal equation matrix is inverted to obtain standard deviations and correlation coefficients. The natural parameters solved for are the broad variations of the gravity field, represented by harmonic coefficients; local variations of gravity, represented by point masses; and the departure of the sea level from the geoid, represented by area means. A standard case of a low (263 km) polar close satellite, three equatorial geosynchronous satellites, and eight ground tracking stations is set up.

Kaula, W. M.

1972-01-01

244

Earth observation system: Spacecraft design  

NASA Technical Reports Server (NTRS)

The Earth Observation Satellite (EOS) was a study funded by NASA Langley Research Center. The study was a system investigation of the total spacecraft integration with its major subsystems and sensors. Mission optimization and ranking using various sensors was also an objective of the contract. Integrating the spacecraft and major subsystems with the large microwave radiometer was done, essentially making the radiometer a free-flyer without an external spacecraft. Another program objective was to provide design and analysis data on microwave radiometer satellites augmented with additional Earth, ocean, and atmospheric sensors. A top-down systems approach resulted in a detailed design integrating subsystems and sensors into the microwave support structure. An important objective of the program was to identify technology needs for Earth observation satellites. The definition and understanding of these design drivers are critical in order to set priorities for future EOS work.

Herbert, J. J.; Schartel, W. A.

1983-01-01

245

Observation of suspended sediments in Mobile Bay, Alabama from satellite  

USGS Publications Warehouse

As part of a comprehensive geologic study of coastal Alabama and Mississippi, the U.S. Geological Survey is investigating coastal sediment transport in Mobile Bay and the adjacent shelf. Satellite imagery from the NOAA AVHRR is being used to provide data on the variability of spatial patterns in the near-surface suspended sediment concentration. This imagery is processed using atmospheric corrections to remove haze and Rayleigh radiance in order to obtain water reflectances; the reflectances are than converted to approximate sediment concentrations using standard relationships between water reflectance and in situ sediment concentrations. A series of images from early 1990 shows rapid changes in sediment concentrations in response to high river flow of the Alabama-Tombigbee river system. During these times, suspended sediment tends to flow out Mobile Bay without mixing into the eastern lobe of the Bay (Bon Secour Bay). The sediment concentration field also appears to be disturbed by the main ship channel. The sediment plume extends more than 60 km offshore after the peak flow event. One wind event in December 1989 was identified as increasing sediment concentration in the Bay. It is not believed that such an event has been previously observed from satellite.

Stumpf, Richard, P.

1991-01-01

246

Unusual satellite data: A black hole?. [International Ultraviolet Explorer observations  

NASA Technical Reports Server (NTRS)

Data obtained by the NASA-launched European Space Agency's International Ultraviolet Explorer satellite suggests the possibility of a massive black hole at the center of some globular clusters (star groups) in our galaxy. Six of these clusters, three of them X-ray sources, were closely examined. Onboard short wavelength UV instrumentation penetrated the background denseness of the clusters 15,000 light years away where radiation, probably from a group of 10 to 20 bright blue stars orbiting the core, was observed. The stars may well be orbiting a massive black hole the size of 1,000 solar systems. The existence of the black hole is uncertain. The dynamics of the stars must be studied first to determine how they rotate in relation to the center of the million-star cluster. This may better indicate what provides the necessary gravitational pull that holds them in orbit.

1978-01-01

247

Military implications of a satellite power system  

Microsoft Academic Search

If a satellite power system (SPS), such as is described in the NASA Reference Design Report, were to be undertaken to provide significant quantities of power to the United States and perhaps to other countries as well, significant military implications would ensue. These would arise, first, from the possible uses of such satellites and supporting systems as weapons or as

J. P. Vajk; R. D. Stutzke; R. Salkeld; G. W. Driggers; G. H. Stine

1981-01-01

248

Satellite multiple access systems for mobile communication  

NASA Technical Reports Server (NTRS)

This paper considers multiple access techniques for a mobile radio system which incorporates a geosynchronous orbiting satellite repeater through which mobile terminals communicate. The communication capacities of FDMA, TDMA and CDMA systems are examined for a 4 MHz bandwidth system to serve up to 10,000 users. An FDMA system with multibeam coverage is analyzed in detail. The system includes an order-wire network for demand-access control and reassignment of satellite channels. Satellite and terminal configurations are developed to a block diagram level and system costs and implementation requirements are discussed.

Lewis, J. L.

1979-01-01

249

Reconfigurability in future communication satellite systems  

NASA Astrophysics Data System (ADS)

Reconfigurability in the Broadcasting Satellite Service (BSS) and in the Fixed Satellite Service (FSS) is examined. The use in BSS of a common spare for different European national satellites is addressed, showing the feasibility of this solution for a system with three satellites in orbit. Solutions involving a repointable antenna with few feed horns and a fixed antenna with more feed horns are described. The use in FSS of a European system at Ku band for the latter 1990s is considered, describing a simplified reconfigurable FSS transmit front end.

Berretta, G.; Roederer, A.

250

Joint Polar Satellite System Common Ground System Overview  

NASA Astrophysics Data System (ADS)

The National Oceanic and Atmospheric Administration (NOAA) and National Aeronautics and Space Administration (NASA) are jointly acquiring the next-generation civilian weather and environmental satellite system: the Joint Polar Satellite System (JPSS). JPSS will contribute the afternoon orbit component and ground processing system of the restructured National Polar-orbiting Operational Environmental Satellite System (NPOESS). As such, JPSS replaces the current Polar-orbiting Operational Environmental Satellites (POES) managed by NOAA and the ground processing component of both Polar-orbiting Operational Environmental Satellites and the Defense Meteorological Satellite Program (DMSP) replacement, previously known as the Defense Weather Satellite System (DWSS), managed by the Department of Defense (DoD). The JPSS satellites will carry a suite of sensors designed to collect meteorological, oceanographic, climatological, and solar-geophysical observations of the earth, atmosphere, and space. The ground processing system for JPSS is known as the JPSS Common Ground System (JPSS CGS), and consists of a Command, Control, and Communications Segment (C3S) and an Interface Data Processing Segment (IDPS). Both segments are developed by Raytheon Intelligence and Information Systems (IIS). The C3S currently flies the Suomi National Polar Partnership (Suomi NPP) satellite and transfers mission data from Suomi NPP and between the ground facilities. The IDPS processes Suomi NPP satellite data to provide Environmental Data Records (EDRs) to NOAA and DoD processing centers operated by the United States government. When the JPSS-1 satellite is launched in early 2017, the responsibilities of the C3S and the IDPS will be expanded to support both Suomi NPP and JPSS-1. The JPSS CGS currently provides data processing for Suomi NPP, generating multiple terabytes per day across over two dozen environmental data products; that workload will be multiplied by two when the JPSS-1 satellite is launched. The CGS also provides raw data processing for GCOM-W1 to support further processing by NOAA. The CGS provides data routing for numerous missions, including Coriolis/Windsat, NASA SCaN (including EOS), DMSP, POES and Metop. Each of these satellites orbits the Earth 14 times a day, downlinking mission data once or twice per orbit at up to hundreds of megabits per second, to support the generation of tens of terabytes per day across hundreds of environmental data products. This presentation will provide an overview of the JPSS CGS ground architecture features, ConOps, key specifications, developmental and operational facilities, present and future supported missions, and recent enhancements for support of the Suomi NPP mission. Key features include redundant mission management, a global commercial communications network for data routing and delivery, high-availability and low-latency data processing, a DoD 8500 compliant security posture, and a modular and extensible architecture. Key recent enhancements include a technology refresh of IDPS hardware to improve supportability and latency performance, incorporation of data routing and processing for the Global Change Observation Mission (GCOM), and significant software upgrades to improve overall system robustness and operability. These enhancements lay the foundation for the future evolution of the CGS to support additional missions.

Jamilkowski, M. L.; Miller, S. W.; Grant, K. D.

2012-12-01

251

Observations of Uranus' satellites: Bibliography and literature search  

NASA Technical Reports Server (NTRS)

A literature search has yielded more than 10,000 observations of the satellites of Uranus made from 1787 to 1985. The type (photographic, micrometer) and the number of observations are tabulated in 5 year increments and a complete bibliography is provided.

Jacobson, R. A.

1985-01-01

252

A Comparison of Techniques for Scheduling Earth Observing Satellites  

Microsoft Academic Search

Scheduling observations by coordinated fleets of Earth Observing Satellites (EOS) involves large search spaces, complex constraints and poorly understood bottlenecks; conditions where stochastic algorithms are often e ective. However, there are many such algo-rithms and the best one to use is not obvious. Here we compare multiple variants of the genetic algorithm, hill climbing, simulated annealing, squeaky wheel op-timization and

Al Globus; James Crawford; Jason D. Lohn; Anna Pryor

2004-01-01

253

Case study - Australian national satellite system  

NASA Astrophysics Data System (ADS)

This paper provides background information on a number of aspects of the decision to proceed to develop an Australian national satellite system, and on the system design. Relevant information includes the Australian geography, climate, and population distribution, the terrestrial telecommunications system, and the broadcasting scene in Australia. The main services to be carried via the satellite system are described, together with the details of the system design against which tenders were called.

Johnson, R. C.

254

Design of the American Mobile Satellite System  

NASA Technical Reports Server (NTRS)

This paper presents an overview of the American Mobile Satellite Corporation (AMSC) Mobile Satellite System (MSS). A summary of the mobile satellite (MSAT) design and overall performance is provided. The design and components of both the forward link and return link transponders are described in detail. The design and operation of a unique hybrid matrix amplifier that offers flexible power distribution is outlined. The conceptual design and performance of three types of land mobile antennas are described.

Kittiver, Charles

1991-01-01

255

Dynamics and control of tethered satellite systems  

NASA Astrophysics Data System (ADS)

Dynamics and control of two-body and n-body tethered satellites are considered. At first, nonlinear roll and pitch motions of two-body systems are examined. Then the effects of aerodynamic and electrodynamic forces on the stability of a tethered satellite are discussed. Various control schemes to stabilize the dynamics during retrieval of the subsatellite are described. Finally, some dynamics and stability results for n-body tethered satellites are presented.

Misra, A. K.

2008-12-01

256

Odyssey, an optimized personal communications satellite system  

NASA Astrophysics Data System (ADS)

Personal communications places severe demands on service providers and transmission facilities. Customers are not satisfied with the current levels of service and want improvements. Among the characteristics that users seek are: lower service rates, hand held convenience, acceptable time delays, ubiquitous service, high availability, reliability, and high quality. The space industry is developing commercial space systems for providing mobile communications to personal telephones. Provision of land mobile satellite service is fundamentally different from the fixed satellite service provided by geostationary satellites. In fixed service, the earth based antennas can depend on a clear path from user to satellite. Mobile users in a terrestrial environment commonly encounter blockage due to vegetation, terrain or buildings. Consequently, high elevation angles are of premium value. TRW studied the issues and concluded that a Medium Earth Orbit constellation is the best solution for Personal Communications Satellite Service. TRW has developed Odyssey, which uses twelve satellites in medium altitude orbit to provide personal communications satellite service. The Odyssey communications system projects a multibeam antenna pattern to the Earth. The attitude control system orients the satellites to ensure constant coverage of land mass and coastal areas. Pointing can be reprogrammed by ground control to ensure optimized coverage of the desired service areas. The payload architecture features non-processing, "bent pipe" transponders and matrix amplifiers to ensure dynamic power delivery to high demand areas. Circuit capacity is 3000 circuits per satellite. Each satellite weighs 1917 kg (4226 pounds) at launch and the solar arrays provide 3126 Watts of power. Satellites are launched in pairs on Ariane, Atlas, or other vehicles. Each satellite is placed in a circular orbit at an altitude of 10,354 km. There are three orbit planes inclined at 55° to the equatorial plane. Deployment of the satellites permits phased introduction of service. After only three launches, in which two satellites are launched into each plane, continuous service can be provided to most of the world. After three more launches for a total of 12 satellites, service can be expanded to all populated regions of the Earth with path diversity to most regions. The Odyssey system is superior to both geostationary satellites and low earth orbiting satellites. Odyssey provides many benefits to the end user which are described in the paper. These include: low cost, convenience, high availability, reliability, and acceptable time delay. Odyssey exhibits benefits for telecommunications operators: simple operations, incremental, phased startup, long space segment life-time, high profitability, dynamic flexibility for adjustment and short time to market. Since submission of an FCC application in 1991, TRW has continued to explore ways to further improve the Odyssey approach by expanding coverage to the entire world and reducing the initial investment while maintaining high quality service.

Rusch, Roger J.

257

Planning and Scheduling for Fleets of Earth Observing Satellites  

NASA Technical Reports Server (NTRS)

We address the problem of scheduling observations for a collection of earth observing satellites. This scheduling task is a difficult optimization problem, potentially involving many satellites, hundreds of requests, constraints on when and how to service each request, and resources such as instruments, recording devices, transmitters, and ground stations. High-fidelity models are required to ensure the validity of schedules; at the same time, the size and complexity of the problem makes it unlikely that systematic optimization search methods will be able to solve them in a reasonable time. This paper presents a constraint-based approach to solving the Earth Observing Satellites (EOS) scheduling problem, and proposes a stochastic heuristic search method for solving it.

Frank, Jeremy; Jonsson, Ari; Morris, Robert; Smith, David E.; Norvig, Peter (Technical Monitor)

2001-01-01

258

Mapping of satellite CO2 observations - novel practical applications  

NASA Astrophysics Data System (ADS)

Emerging satellite observations of carbon dioxide (CO2) offer new and distinctive opportunities to improve our quantitative knowledge of the carbon cycle. Certain characteristics of CO2 satellite observations, however, are challenging because they often contain large gaps, occur in clusters, can be biased and have high measurement errors; i.e. the signal-to-noise ratio is low. The statistical mapping methodology presented here can work with these challenges and is a comparatively direct and fast way to capitalize on CO2 satellite observations to improve our knowledge of the carbon cycle. This approach makes it possible to map global atmospheric CO2 concentrations for time scales consistent with the synoptic dynamics of CO2, and can provide uncertainties that correctly reflect the true uncertainty of the mapped concentrations. Minimal assumptions are made, namely that the atmospheric CO2 concentrations exhibit spatial correlation, and that the statistical characteristics of this correlation can be inferred from the observations. The method is hence well suited to create observation-based CO2 mapping products that are independent of any a priori transport or flux assumptions. Practical applications of the mapping products include studies that compare observations to models, evaluate the ability of satellite observations to detect carbon flux perturbations, and compare retrieval algorithms. Specific results from such studies are shown and include a model comparison study using the Greenhouse gases Observing SATellite (GOSAT) observations, an evaluation of the ability of the Active Sensing of CO2 Emissions over Nights, Days, and Seasons (ASCENDS) mission to detect carbon flux perturbations, and a comparison of different GOSAT retrieval algorithms.

Hammerling, D.

2012-12-01

259

Global Positioning System Satellite Selection Method  

NASA Technical Reports Server (NTRS)

The satellite selection method as utilized by the spaceborne Global Positioning System receiver provides navigational solutions and is designed for use in low Earth orbit. The satellite selection method is a robust algorithm that can be used a GPS receiver to select appropriate GPS satellites for use in calculating point solutions or attitude solutions. The method is takes into account the difficulty of finding a particular GPS satellite phase code, especially when the search range in greatly increased due to Doppler shifts introduced into the carrier frequency. The method starts with an update of the antenna pointing and spacecraft vectors to determine the antenna backplane direction. Next, the GPS satellites that will potentially be in view of the antenna are ranked on a list, whereby the list is generated based on the estimated attitude and position of each GPS satellite. Satellites blocked by the Earth are not entered on this list. A second list is created, whereby the GPS satellites are ranked according to their desirability for use in attitude determination. GPS satellites are ranked according to their orthogonality to the antenna backplane, and according to geometric dilution of precision considerations. After the lists are created, the channels of the spaceborne GPS receiver are assigned to various GPS satellites for acquisition and lock. Preliminary Doppler frequencies for searching are assigned to the various channels.

Niles, Frederick A. (Inventor)

2001-01-01

260

Transient response measurements on a satellite system  

NASA Technical Reports Server (NTRS)

A set of instruments designed to detect the occurance of electrical breakdown was flown on a synchronous-orbit satellite. The LeRC sensors were installed on cables inside the vehicle. Accordingly, they respond to signals coupled into the satellite wiring system. The SRI sensors were located on the exterior of the vehicle and detected the RF noise pulses associated with surface breakdowns. The results of the earlier SRI program are being used to design and develop a set of intrumentation suitable for inclusion as a general piggy-back package for the detection of the onset of satellite charging and breakdowns on synchronous orbit satellites.

Nanevicz, J. E.; Adamo, R. C.

1977-01-01

261

Asian Dust Weather Categorization with Satellite and Surface Observations  

NASA Technical Reports Server (NTRS)

This study categorizes various dust weather types by means of satellite remote sensing over central Asia. Airborne dust particles can be identified by satellite remote sensing because of the different optical properties exhibited by coarse and fine particles (i.e. varying particle sizes). If a correlation can be established between the retrieved aerosol optical properties and surface visibility, the intensity of dust weather can be more effectively and consistently discerned using satellite rather than surface observations. In this article, datasets consisting of collocated products from Moderate Resolution Imaging Spectroradiometer Aqua and surface measurements are analysed. The results indicate an exponential relationship between the surface visibility and the satellite-retrieved aerosol optical depth, which is subsequently used to categorize the dust weather. The satellite-derived spatial frequency distributions in the dust weather types are consistent with China s weather station reports during 2003, indicating that dust weather classification using satellite data is highly feasible. Although the period during the springtime from 2004 to 2007 may be not sufficient for statistical significance, our results reveal an increasing tendency in both intensity and frequency of dust weather over central Asia during this time period.

Lin, Tang-Huang; Hsu, N. Christina; Tsay, Si-Chee; Huang, Shih-Jen

2011-01-01

262

Solar power satellite system definition study  

NASA Technical Reports Server (NTRS)

A synopsis of the study plan for the solar power satellite system is presented. Descriptions of early task progress is reported for the following areas: (1) laser annealing, (2) solid state power amplifiers, (3) rectenna option, (4) construction of an independent electric orbit transfer vehicle, and (5) construction of a 2.5 GW solar power satellite.

1978-01-01

263

New options for satellite power systems \\/SPS  

Microsoft Academic Search

The operation of a satellite power system (SPS) involves the conversion of solar energy into electrical energy with the aid of facilities carried by a geosynchronous satellite, the transmission of the obtained energy to earth in the form of microwave radio frequency energy, and the conversion of the energy received on earth into dc current for distribution into the network.

G. M. Hanley

1977-01-01

264

Propagation Effects Handbook for Satellite Systems Design  

Microsoft Academic Search

This paper describes the latest edition of the NASA Propagation Effects Handbook for Satellite Systems Design and presents a summary of application of the handbook information to satellite link design and performance. NASA, which has supported a large part of the experimental work in radiowave propagation on space communications links, recognized the need for a reference handbook of this type,

Louis J. Ippolito

265

Studies of the Major Planet Satellite Systems.  

National Technical Information Service (NTIS)

A summary is presented of the available data on the satellites of the major planets, including the currently most plausible models for several observed phenomena, for the planning of spacecraft missions to these objects. Some of the important questions li...

H. Frey P. D. Lowman

1974-01-01

266

Interactive applications of satellite observations and mesoscale numerical models  

NASA Technical Reports Server (NTRS)

The impact of numerical weather prediction (NWP) and satellite meteorology on operational weather forecasting has become overwhelming in the past few years. The paper looks toward the merger of these technologies in making short range 6-18 h forecasts through the use of mesoscale NWP models. A short-range (2-18 h) mesoscale forecast system envisioned for the near future is described that includes four components: hydrodynamic numerical models, large-scale and mesoscale; satellites, polar orbiting for high latitudes and geostationary for low latitudes; mesoclimatology, derived in large part from satellite data; and special-purpose simple models and empirical relations. It is important that the components of the forecast system be developed in parallel rather than in series if the system is to be completed within five years. There is enough evidence to substantiate the revolution in the mesoscale weather prediction in the next five years.

Kreitzberg, C. W.

1976-01-01

267

NASDA satellite mission operation system and operations  

NASA Technical Reports Server (NTRS)

NASDA has recently developed a new tracking and control system as a basis for future satellite mission operation. It is named type-I Space Operations and Data Systems (type-I SODS). The software of this system is separated into three parts: operation and control system, network system, and support and information system. The operation control system treats telemetry and command operations. The network system controls the communication line and ground station equipments to connect the satellite and the operation control system. The support and information system provides to other systems necessary information. JERS-1 which was launched in February of this year is the first satellite operated by type-l SODS. We explain the architecture and operation methods of this system using JERS-1 mission operations.

Yamaya, Kousaku; Yoshida, Fumiyoshi; Noguchi, Harushige; Takahashi, Tetsuo; Tanaka, Kazuhiro

1993-01-01

268

Ground-based and satellite observations of substorm onset features  

NASA Astrophysics Data System (ADS)

We present the ground-based and satellite observations of substorm onset events. In the observations from Ground Based Observatories (GBO) and the ISUAL/FORMOSAT-2 satellite, we find structures which consist of periodic bright spots on the auroral arc prior to the substorm expansion phase onset. The intensity of arc grows exponentially before breakup with a linear growth rate of ~O(1-3)sec-1. Under the arc, the negative H-bay associated with the substorm is evident in the ground-based magnetometer data. From ISUAL observations, the first auroral brightening is identified roughly at the beginning of the negative H-bay. The auroral arc is breaks up before dispersionless particle injections are observed at geosynchronous orbit. Based on analysis of these observations, we suggest that this event can be a support of the scenario of substorm onset which is caused by a kinetic ballooning instability which is localized at ~ -10RE.

Chang, T.; Cheng, C. Z.; Chiang, C.; Tam, S. W.; Chen, A. B.; Hsu, R.; Su, H.

2009-12-01

269

Sensor Web Interoperability Testbed Results Incorporating Earth Observation Satellites  

NASA Technical Reports Server (NTRS)

This paper describes an Earth Observation Sensor Web scenario based on the Open Geospatial Consortium s Sensor Web Enablement and Web Services interoperability standards. The scenario demonstrates the application of standards in describing, discovering, accessing and tasking satellites and groundbased sensor installations in a sequence of analysis activities that deliver information required by decision makers in response to national, regional or local emergencies.

Frye, Stuart; Mandl, Daniel J.; Alameh, Nadine; Bambacus, Myra; Cappelaere, Pat; Falke, Stefan; Derezinski, Linda; Zhao, Piesheng

2007-01-01

270

CORRECTING PHOTOLYSIS RATES ON THE BASIS OF SATELLITE OBSERVED CLOUDS  

EPA Science Inventory

Clouds can significantly affect photochemical activities in the boundary layer by altering radiation intensity, and therefore their correct specification in the air quality models is of outmost importance. In this study we introduce a technique for using the satellite observed c...

271

Observations of orbital debris and satellites in Slovak Republic  

Microsoft Academic Search

There are many accidental optically tracked artificial objects during observations at Astronom-ical and Geophysical Observatory FMPI CU, Modra, Slovak Republic (AGO). Those objects are usually orbital debris or satellites. A tool to identify such a type of objects was necessary to create. Our software is called SatEph and is used to identify tracked artificial objects and to compute their orbital

Jiri Silha; Juraj Toth

2010-01-01

272

Observed Weather Satellite Thermal IR Responses Prior to Earthquakes  

Microsoft Academic Search

A number of observers claim to have seen thermal anomalies prior to earthquakes, but subsequent analysis by others have failed to produce similar findings. It was the purpose of this study to determine if thermal anomalies could be found in association with known earthquakes by systematically co-registering weather satellite images at the sub-pixel level and then determining if statistically significant

N. A. Bryant; A. L. Zobrist; L. L. Logan; F. Freund; S. Nishenko

2002-01-01

273

Discrete particle release observed on the Midcourse Space Experiment satellite  

Microsoft Academic Search

Particle occurrence rates, velocities, size distributions, and trends in the environment have been measured above the Midcourse Space Experiment satellite using optical sensors. Results from the spacecraft's first year on orbit are presented. Particles were detected during relatively quiescent times and as a result of distinct particle release events. On 11 November 1996, we observed a discrete particle release even

Gary E. Galica; B. David Green; O. Manuel Uy; David M. Silver; Richard C. Benson; Jeffrey C. Lesho; Mark T. Boies; Bob E. Wood; David F. Hall

1998-01-01

274

Geostationary Atmospheric Observation Satellite Plan in Japan (Invited)  

NASA Astrophysics Data System (ADS)

As emissions of air pollutants in Asia have increased in the past decades accompanying with rapid economic growth of developing countries, Asian regional air pollution has attracted concern from the view of inter-continental and intra-continental long-range transport as well as domestic air quality. Particularly in Japan, transboundary transport of ozone is of recent social concern as one of a cause of increasing trend of near surface ozone concentration. In order to elucidate the transport and chemical transformation processes of air pollution in East Asia, and to attain internationally common understanding on this issue, geostationary atmospheric observation satellite has been proposed in Japan. In 2006, the Japan Society of Atmospheric Chemistry (JSAC) formed Commission on the Atmospheric Environmental Observation Satellite to initiate the discussion. In 2009, Committee on Geostationary Atmospheric Observation Satellite has been formed within JAXA to promote the plan. The proposed satellite consists of a UV/VIS sensor for O3, NO2, HCHO and AOT, and a MIR sensor for O3, CO, HNO3, NO2, H2O and temperature. Targeted spatial and temporal resolutions are ca.10 km and 1-2 hrs, respectively, and focused observation area is northeast Asia potentially covering the southeast and south Asia. Sensitivity analysis and simulation have been made for both the UV/VIS and MIR sensors. Overview of user requirement and the sensitivity analysis for each species will be presented in this talk.

Akimoto, H.; Kasai, Y.; Kita, K.; Irie, H.; Sagi, K.; Hayashida, S.

2009-12-01

275

Gravity waves in the thermosphere observed by the AE satellites  

NASA Technical Reports Server (NTRS)

Atmospheric Explorer (AE) satellite data were used to investigate the spectra characteristics of wave-like structure observed in the neutral and ionized components of the thermosphere. Power spectral analysis derived by the maximum entropy method indicate the existence of a broad spectrum of scale sizes for the fluctuations ranging from tens to thousands of kilometers.

Gross, S. H.; Reber, C. A.; Huang, F. T.

1983-01-01

276

Satellite Observations of Bremsstrahlung From Widespread Energetic Electron Precipitation Events  

Microsoft Academic Search

This is a preliminary report of the first satellite observations that have been made of the intensities and energy spectra of the bremsstrahlung >50, keV produced in the atmosphere by intense widespread precipitations of energetic electrons from the outer radiation belt. The measurements afford the opportunity to investigate nearly simultaneously the energetic electron behavior on a worldwide scale during magnetic

W. L. Imhof; G. H. Nakano; R. G. Johnson; J. B. Reagan

1974-01-01

277

CCD observations of planetary satellites at the U.S. Naval Observatory.  

NASA Astrophysics Data System (ADS)

A program of astrometric CCD observations of faint satellites of the planets was initiated at the U.S. Naval Observatory (USNO) to complement their photographic program for the bright satellites (Pascu 1979, Pascu et al. 1983). The program emphasizes the faint inner satellites for which the CCD is better adapted. Included in this group are Amalthea (JV), Thebe (JXIV), Helene (SXII), Telesto (SXIII), Calypso (SXIV), Miranda (UV), and Nereid (NII). Almost all of the faint outer satellites are also being observed with a CCD. In addition, an experimental program for high precision observations of the Galilean satellites was begun two years ago in support of the GALILEO Project. At present, 25 satellites cannot be observed from the ground at all, or with great difficulty. Of these, about 15 can be detected with the CCDs in the Wide Field Planetary Camera II of the Hubble Space Telescope. The USNO participates on a team which is analyzing HST astrometric observations of the inner Uranian system and is making plans to obtain similar observations of the inner Neptunian system.

Pascu, D.

1996-02-01

278

Globally Gridded Satellite (GridSat) Observations for Climate Studies  

NASA Technical Reports Server (NTRS)

Geostationary satellites have provided routine, high temporal resolution Earth observations since the 1970s. Despite the long period of record, use of these data in climate studies has been limited for numerous reasons, among them: there is no central archive of geostationary data for all international satellites, full temporal and spatial resolution data are voluminous, and diverse calibration and navigation formats encumber the uniform processing needed for multi-satellite climate studies. The International Satellite Cloud Climatology Project set the stage for overcoming these issues by archiving a subset of the full resolution geostationary data at approx.10 km resolution at 3 hourly intervals since 1983. Recent efforts at NOAA s National Climatic Data Center to provide convenient access to these data include remapping the data to a standard map projection, recalibrating the data to optimize temporal homogeneity, extending the record of observations back to 1980, and reformatting the data for broad public distribution. The Gridded Satellite (GridSat) dataset includes observations from the visible, infrared window, and infrared water vapor channels. Data are stored in the netCDF format using standards that permit a wide variety of tools and libraries to quickly and easily process the data. A novel data layering approach, together with appropriate satellite and file metadata, allows users to access GridSat data at varying levels of complexity based on their needs. The result is a climate data record already in use by the meteorological community. Examples include reanalysis of tropical cyclones, studies of global precipitation, and detection and tracking of the intertropical convergence zone.

Knapp, Kenneth R.; Ansari, Steve; Bain, Caroline L.; Bourassa, Mark A.; Dickinson, Michael J.; Funk, Chris; Helms, Chip N.; Hennon, Christopher C.; Holmes, Christopher D.; Huffman, George J.; Kossin, James P.; Lee, Hai-Tien; Loew, Alexander; Magnusdottir, Gudrun

2012-01-01

279

Satellite tether systems: Dynamic modeling and control  

NASA Astrophysics Data System (ADS)

Over the last few decades, researchers have realized many potential applications of tethered satellite systems that include atmospheric data collection, placing satellites from low earth orbits into higher orbits, capture of non-functional satellites for service and repair, satellite reboost and deorbiting. The deployment/retrieval dynamics of such systems due to gravity gradient forces is highly nonlinear in nature. Also, due to orbital motion, the longitudinal and transverse motions are coupled. With only boundary control, the tethered satellite system forms a highly underactuated system. In this thesis, we derive and validate the deployment dynamics of such a system following two different basic approaches---Newton's laws and Hamilton's principle. The complexity of the system is studied in an incremental nature using three different models. The problem of controlled deployment/retrieval is approached using a partial feedback linearizing controller. The problem of station keeping is tackled in a more novel way by developing a boundary controller based on the linearization of the infinite dimensional tether system around radial relative equilibrium configuration. Lyapunov function is used to study the stability of the controller on the linearized system. Effectiveness of controllers developed for deployment and station keeping are verified through simulations. We have also studied the dynamics of tethered satellite systems in the presence of electrodynamic forces due to the magnetic field of the earth. We propose a novel method to the control the tether configurations in the presence of electrodynamic forces.

Mankala, Kalyan K.

280

MPEG-7 Descriptors for Earth Observation Satellite Images  

NASA Astrophysics Data System (ADS)

The amount of digital multimedia information has experienced a spectacular growth during the last years thanks to the advances on digital systems of image, video and audio acquisition. As a response to the need of organising all this information, ISO/IEC has developed a new standard for multimedia content description called MPEG-7. Among other topics, MPEG-7 defines a set of multimedia descriptors that can be automatically generated using signal processing techniques. Earth Observation Satellites generate large quantities of images stored on enormous databases that can take advantage of the new standard. An automatic indexation of these images using MPEG-7 metadata can improve their contents management as well as simplify interaction between independent databases. This paper gives an overall description on MPEG-7 standard focusing on the low-level Visual Descriptors. These descriptors can be grouped into four categories: color, texture, shape and motion. Visual Color Descriptors represent the colour distribution of an image in terms of a specified colour space. Visual Texture Descriptors define the visual pattern of an image according to its homogenities and non-homogenities. Visual Shape Descriptors describe the shape of 2D and 3D objects being, at the same time, invariant to scaling, rotation and translation. Motion Descriptors give the essential characteristics of objects and camera motions. These descriptors can be used individually or in combination to index and retrieve satellite images of the Earth from a database. For example, oceans and glaciars can be discerned based on their Colour Descriptors, also cities and deserts based on the Texture Descriptors, island images can be grouped using the Shape Descriptors, and cyclone trajectories studied and compared using the Motion Descriptors.

Nieto, X. Giro I.; Marques Acosta, F.

281

A new digital land mobile satellite system  

NASA Technical Reports Server (NTRS)

A description is given of the different digital services planned to be carried over existing and planned mobile satellite systems. These systems are then compared with analog services in terms of bandwidth and power efficiency. This comparison provides the rationale for the establishment of a digital land mobile satellite service (DLMSS) to use frequencies that are currently available but not yet assigned to a domestic mobile satellite system in the United States. The focus here is on the expected advantages of digital transmission techniques in accommodating additional mobile satellite systems in this portion of the spectrum, and how such techniques can fully satisfy voice, data and facsimile mobile communications requirements in a cost effective manner. A description is given of the system architecture of the DMLSS service proposed by the Geostar Messaging Corporation (GMC) and the market potential of DLMSS.

Schneider, Philip

1990-01-01

282

Satellite systems requirements for land mobile communications  

NASA Technical Reports Server (NTRS)

The system design objective is to provide a satellite link through a gateway station, connecting mobile users in areas not served by a terrestrial cellular system to the switched telephone network (STN). The proposed frequency allocation comprises a pair of 10-MHz bands in the 806-890 MHz range specified by the 1979 World Administrative Radio Conference (WARC) for land-mobile satellite service (LMSS). The satellite design is constrained by projected STS capability with an upper stage of the wide-body Centaur or Integral Propulsion System (IPS) type. For the latter (a TRW design), the payload is limited to approximately 10,400 lb. The design is to be based on 1990's technology, with initial operating capability scheduled for 1995. The satellite should be designed for a 7-year life. Mobile-unit compatibility with cellular system specifications is desirable, if consistent with other system requirements.

Horstein, M.

1983-01-01

283

Satellite observations of transient radio impulses from thunderstorms  

SciTech Connect

Transient radio emissions from thunderstorms detected by satellites were first reported in 1995. The nature and source of these emissions remained a mystery until the launch of the FORTE satellite in 1997. FORTE, with its more sophisticated triggering and larger memory capacity showed that these emissions were connected to major thunderstorm systems. The analysis reported here, connecting FORTE RF events with ground based lightning location data from the National Lightning Detection Network (NLDN), shows that localized regions within thunderstorms are responsible for the creation of the satellite detected rf signals. These regions are connected with the areas of strong radar returns from the NEXRAD Doppler radar system, indicating that they are from regions of intense convection. The authors will also show data from several storms detected in the extended Caribbean, in which the height profile of the source regions can be determined. Although as a single low earth orbit satellite FORTE cannot provide global coverage of thunderstorm/lightning events, follow-on satellite constellations should be able to provide detailed information on global lightning in near real-time.

Argo, P.E.; Kirkland, M.; Jacobson, A.; Massey, R.; Suszynsky, D.; Eack, K.; Fitzgerald, T.J.; Smith, D.

1999-06-01

284

Solar energy system with relay satellite  

SciTech Connect

A system is described for beaming solar energy from space to an earth location and putting it to useful work either as heat or light energy, or by converting it into some other form of energy such as steam or electrical power. In the system illustrated, a receiver satellite is in polar orbit and a relay satellite is in equatorial orbit, rotating with the earth and therefore stationary with respect to earth location. Solar energy is collected by the receiver satellite through an array of parabolic collectors and focused by a series of mirrors onto a coherent radiation energy generator, preferably a laser beam generator. The laser beam is directed by a mirror to another mirror on the relay satellite which redirects it to a selected earth location. Alternatively, the relay satellite may convert the laser beam to a maser beam to better penetrate clouds, smoke and haze at the earth location. The mirrors on the two satellites are mounted on gimbals and are power-operated under continuous automatic telemetry control between the satellites and the ground to direct the laser or maser beam to the eath location. Provision is made on one of the satellites for modifying the beam through a constructive interference filter or a diffuser/expander lens, or both, to regulate the kind of energy and the area covered at the earth location.

Davis, C.E.

1981-12-15

285

Monitoring of Observation Errors from Satellite Ozone Instruments in Assimilation  

NASA Technical Reports Server (NTRS)

Ozone distributions derived from the Solar Backscatter UltraViolet/2 (SBUV/2) instruments and the Earth Probe Total Ozone Mapping Spectrometer (EP TOMS) have been assimilated in near-real time at the NASA/Goddard Data Assimilation Office since January 2000. Observed-minus-forecast (O-F) residuals are the differences between the incoming ozone data and the co-located short-term model forecast. They are routinely produced and monitored in the assimilation process. Using examples from the NOAA-14 and NOAA-16 SBUV/2 and the EP-TOMS instruments, it is demonstrated that the monitoring of time series of O-F residual statistics is an effective method of identifying time-dependent changes in the observation-error characteristics of ozone. In addition, the data assimilation system was used to assist the validation of updated calibration coefficients for the NOAA-14 SBUV/2 instrument. This assimilation-based monitoring work will be extended to ozone data from instruments on new satellites: Envisat EOS, Aqua, and EOS Aura.

Stajner, Ivanka; Winslow, Nathan; Rood, Richard B.; Pawson, Steven

2002-01-01

286

Generation of VLF saucer emissions observed by the Viking satellite  

SciTech Connect

The authors report observations of V shaped saucer emissions by the Viking satellite. This V shaped saucer emission refers to the observational feature of the VLF or ELF emissions which shows a v shaped appearance on a plot of frequency as a function of time. Viking provided not only wave, but electric and magnetic field measurements, as well as charged particle measurements. These measurements show electrons flowing upwards with enegies of up to a few hundred eV in conjunction with the saucer emissions. Other wave structures observed in this same region may originate from the electron flows. The satellite observations also find such events at altitudes from 4000 to 13000km, where the generation region is found to be much more spread out in space.

Loennqvist, H. [Swedish Institute of Space Physics, Uppsala (Sweden); Andre, M.; Matson, L. [Univ. of Umea (Sweden); Bahnsen, A. [Danish Space Research Institute, Lyngby (Denmark); Blomberg, L.G. [Royal Institute of Technology, Stockholm (Sweden); Erlandson, R.E. [Johns Hopkins Univ., Laurel, MD (United States)

1993-08-01

287

Dynamics Explorer 2 satellite observations and satellite track model calculations in the cusp\\/cleft region  

Microsoft Academic Search

The authors present two detailed cases of the ionospheric and thermospheric response to soft particle precipitation in the cusp\\/cleft region using multi-instrument observations from the Dynamics Explorer 2 (DE 2) satellite during orbits 688 and 748, together with supporting model calculations. The experimental data set is among the most comprehensive reported to date and includes a specification of both soft

Q. Wu; T. L. Kilelen; A. G. Burns; W. Deng; J. D. Winningham; N. W. Spencer; R. A. Heelis; W. B. Hanson

1996-01-01

288

Dynamics Explorer 2 satellite observations and satellite track model calculations in the cusp\\/cleft region  

Microsoft Academic Search

We present two detailed case studies of the ionospheric and thermospheric response to soft particle precipitation in the cusp\\/cleft region using multi-instrument observations from the Dynamics Explorer 2 (DE 2) satellite during orbits 688 and 748, together with supporting model calculations. The experimental data set is among the most comprehensive reported to date and includes a specification of both the

Q. Wu; T. L. Kilelen; W. Deng; A. G. Burns; J. D. Winningham; N. W. Spencer; R. A. Heelis; W. B. Hanson

1996-01-01

289

A glimpse at the GOCE satellite gravity gradient observations  

NASA Astrophysics Data System (ADS)

Since 30 September 2009, following the launch and in-orbit testing of the most sophisticated gravity mission ever built, the European Space Agency (ESA) GOCE satellite is in ‘measurement mode’, providing continuous time series of satellite gravity gradient (SGG) observations and GPS satellite-to-satellite tracking (SST) observations. The availability of GPS SST observations allows the precise reconstruction of the GOCE position and thus the precise geolocation of the SGG observations. The SGG observations are based on the differences between observations taken by pairs of accelerometers, which need to be corrected first by applying a so-called calibration matrix and second by subtracting rotational terms (centrifugal and angular accelerations).The GOCE mission is designed to provide SGG observations that are most precise in a bandwidth ranging from 0.005 to 0.1 Hz, equivalent to spatial scales along the satellite flight path of about 80-1600 km. Therefore, the SGG observations need to be bandpass filtered. Two months of GOCE SGG observations covering November and December 2009 (first release by ESA) have been processed and analyzed in the spatial domain by comparison with gradients predicted with state-of-the-art gravity field models (EIGEN-5C and ITG-Grace2010s). The ITG-Grace2010s model displays a high level of consistency with the four SGG components that are designed to be observed precisely, except for the cross-track diagonal component at the low frequency end of the measurement bandwidth (close to 0.005 Hz) for which the differences are about a factor 3 higher. For the EIGEN-5C model, a similar consistency is observed, except for geographical areas where this prior model is considered to be less accurate, such as the Himalayan and Andes mountain ranges, the Indonesian Archipelago and Antarctica. The root-mean-square (RMS) of differences between 1 Hz GOCE SGG observations and those predicted by the prior models is below the signal size for frequencies up to at least 0.04 Hz, indicating the high quality of these observations, and also the models, over a large part of the measurement bandwidth.

Visser, P. N. A. M.

2011-02-01

290

Whistler-triggered emissions observed by ISIS satellites  

NASA Technical Reports Server (NTRS)

A statistical examination has been conducted of the ducted and nonducted whistler-triggered emissions (WTEs) observed by the ISIS satellites in the 1979-1981 period. Most WTEs are observed with simultaneous lower hybrid resonance in the topside ionosphere. The VLF emissions triggered by ducted whistlers frequently occur at L of 2-3, while those triggered by nonducted whistlers occur in the wider latitudinal regions at L of 2.2-4.3.

Nakamura, Y.; Ondoh, T.

1989-01-01

291

Transient airglow enhancement by lightning observed by satellite  

NASA Astrophysics Data System (ADS)

Transient airglow produced by lightning has been observed in many space missions. The ISUAL instrument on board the FORMOSAT 2 satellite has observed numerous cases of lightning events including sprite, ELVE, halo, and the enhancement in airglow layers for both OH and O2 airglow. The lightning events can produce excited states which react with background atmosphere to produce enhanced airglow. A mechanism involving O(1D) is discussed here.

Nee, J. B.; Dalgarno, A.

2008-12-01

292

Developing a Global Aeronautical Satellite System.  

National Technical Information Service (NTIS)

Arinc, an airline industry-owned and operated company in the United States, has taken steps toward establishing a global aeronautical satellite communications system. Plans call for initiation of a thin-route data operation in 1989, upgrading to establish...

D. K. Dement

1988-01-01

293

NASA Satellite Observations: A Unique Asset for the Study of the Environment and Implications for Public Health  

NASA Technical Reports Server (NTRS)

This slide presentation highlights how satellite observation systems are assets for studying the environment in relation to public health. It includes information on current and future satellite observation systems, NASA's public health and safety research, surveillance projects, and NASA's public health partners.

Estes Sue M.

2010-01-01

294

A small terminal for satellite communication systems  

NASA Technical Reports Server (NTRS)

A small portable, low-cost satellite communications terminal system incorporating a modulator/demodulator and convolutional-Viterbi coder/decoder is described. Advances in signal processing and error-correction techniques in combination with higher power and higher frequencies aboard satellites allow for more efficient use of the space segment. This makes it possible to design small economical earth stations. The Advanced Communications Technology Satellite (ACTS) was chosen to test the system. ACTS, operating at the Ka band incorporates higher power, higher frequency, frequency and spatial reuse using spot beams and polarization.

Xiong, Fuqin; Wu, Dong; Jin, Min

1994-01-01

295

Satellite voice broadcast. Volume 2: System study  

NASA Technical Reports Server (NTRS)

The Technical Volume of the Satellite Broadcast System Study is presented. Designs are synthesized for direct sound broadcast satellite systems for HF-, VHF-, L-, and Ku-bands. Methods are developed and used to predict satellite weight, volume, and RF performance for the various concepts considered. Cost and schedule risk assessments are performed to predict time and cost required to implement selected concepts. Technology assessments and tradeoffs are made to identify critical enabling technologies that require development to bring technical risk to acceptable levels for full scale development.

Bachtell, E. E.; Bettadapur, S. S.; Coyner, J. V.; Farrell, C. E.

1985-01-01

296

Satellite voice broadcast. Volume 2: System study  

NASA Astrophysics Data System (ADS)

The Technical Volume of the Satellite Broadcast System Study is presented. Designs are synthesized for direct sound broadcast satellite systems for HF-, VHF-, L-, and Ku-bands. Methods are developed and used to predict satellite weight, volume, and RF performance for the various concepts considered. Cost and schedule risk assessments are performed to predict time and cost required to implement selected concepts. Technology assessments and tradeoffs are made to identify critical enabling technologies that require development to bring technical risk to acceptable levels for full scale development.

Bachtell, E. E.; Bettadapur, S. S.; Coyner, J. V.; Farrell, C. E.

1985-11-01

297

25-Year Ocean Wind Climatology from Satellite Observations  

NASA Astrophysics Data System (ADS)

A consistently processed ocean wind climatology derived from 10 satellite microwave sensors is now available. This array of satellites extends from 1987 to present and includes 6 SSM/I, AMSR-E, WindSat, F17 SSM/IS, and QuikScat. Two of the satellite sensors, WindSat and QuikScat, provide wind direction in addition to wind speed. This ocean wind climatology is the basis for the cross-calibrated, multi-platform (CCMP) wind product. CCMP assimilates these satellite winds along with conventional ship and buoy wind observations using the ECMWF analysis as a background field to produce 6-hour vector wind fields at a 25-km resolution. The satellite wind retrievals from these multi-platforms have been carefully inter-calibrated, and the typical annual, globally averaged differences among the satellites are less than 0.1 m/s. The error (2-sigma) in the resulting decadal wind trends over the 25-years is estimated to be about 0.06 m/s/decade. Observed large-scale regional wind trends can be as large as 0.5 m/s/decade and hence are well above the noise level of estimating trends. We will present an overview of the ocean wind climatology and the methodology used to inter-calibrate the various sensors. Wind timeseries from the various sensors will be inter-compared with each other and with ocean buoys. An analysis of estimated trend error will be presented. Finally, some examples of global wind trends over the last quarter century will be shown.

Wentz, F. J.; Ricciardulli, L.; Smith, D. K.

2012-12-01

298

FPGA Platform for Satellite Observations of VLF Emissions  

NASA Astrophysics Data System (ADS)

Transient Luminous Events (TLEs) are unique high-altitude phenomena which have recently been the subject of intense study because they may provide insight into the energy exchange and electromagnetic coupling of the high atmosphere and ionosphere. The systematic observation of TLEs is a difficult problem due to their rare occurrence and low signal levels. Historically, optical observations have been the primary method, and recent research indicates a potential correlation between TLE optical emissions and Very Low Frequency (VLF) radio emissions of a particular signature. Two opportunities present themselves for unique instrumentation development: first, a low-order "always-on" sensor placed in-situ on board an observational satellite can record all VLF emissions and gather statistical data on the correlation and rate of occurrence of these VLF signatures. Secondly, such a sensor can serve as a triggering mechanism to activate high-fidelity optical instruments to catch the TLE events in real time. Both of these scenarios present difficult challenges - real-time signal detection requires fast computations; and the space-environment requires both low-power consumption and high resilience to radiation. In light of these constraints, the preferred method is a specialized digital signal processor (DSP) implemented as a Field Programmable Gate Array (FPGA). This technology enables highly parallelizable data processing and due to the specialized hardware specific to this application, power consumption can be reduced. The development of FPGA platforms also offers the capability for extensibility and interoperability with similar ground-stations; additional features such as data recording, user-interfacing, and network connectivity are possible without total system redesign via the FPGA's unique development methodology. Currently, a hardware prototype has been developed which successfully performs the basic functionality for real-time signal processing and data presentation. Using satellite data from the DEMETER probe, algorithms were designed which could suitably detect the VLF signatures of interest, and these techniques were translated into the FPGA's platform for real-time performance. Systematic benchmarking with this data has verified that the implementation is capable of sustaining high-sensitivity detection, even in noisy environments, by dynamically adapting to the signal environment. This instrument enables statistical characterization of these VLF signatures; further work on the prototype platform will enable rapid delivery and visualization of the scientific data.

Moussa, N.; Linscott, I.; Inan, U.

2008-12-01

299

Time Resolved Atmospheric Carbon Satellite Observations from Geostationary Orbit  

NASA Astrophysics Data System (ADS)

This presentation describes proposed satellite carbon measurements from CHRONOS (Commercially Hosted spectroRadiometer Observations and New Opportunities for Science). The primary goal of this mission is to measure the atmospheric pollutants carbon monoxide (CO) and methane (CH4) from geostationary orbit, with hourly observations of North America at high spatial resolution. Carbon monoxide is produced by combustion processes such as urban activity and wildfires, and serves as a proxy for other combustion pollutants that are not easily measured. Both CO and CH4 are chemical precursors of tropospheric ozone pollution. Methane has diverse anthropogenic sources ranging from fossil fuel production, animal husbandry, agriculture and waste management. The impact of gas exploration in the Western States of the USA and oil extraction from the Canadian tar sands will be particular foci of the mission, as will the poorly-quantified natural CH4 emissions from wetlands and thawing permafrost. In addition to characterizing pollutant sources, improved understanding of the domestic CH4 budget is a priority for policy decisions related to short-lived climate forcers. A primary motivation for targeting CO is its value as a tracer of atmospheric pollution. The CHRONOS measurements will provide insight into local and long-range transport across the North American continent, as well as the processes governing the entrainment and venting of pollution in and out of the planetary boundary layer. As a result of significantly improved characterization of diurnal changes in atmospheric composition, CHRONOS observations will find direct societal applications for air quality regulation and forecasting. We present a quantification of this expected improvement in the prediction of near-surface concentrations when CHRONOS measurements are used in Observation System Simulation Experiments (OSSEs). If CHRONOS and the planned NASA Earth Venture TEMPO (Tropospheric Emissions: Monitoring of Pollution) mission were implemented concurrently, the resulting measurement suite would efficiently and expeditiously serve to address the science goals of the Decadal Survey proposed GEO-CAPE mission.

Edwards, D. P.; Worden, H. M.; Deeter, M. N.; Worden, H. M.

2013-12-01

300

Satellite power system (SPS) initial insurance evaluation  

SciTech Connect

The beginning of a process to educate the insurance industry about the Satellite Power System is reported. The report is divided into three sections. In the first section a general history describes how space risks are being insured today. This is followed by an attempt to identify the major risks inherent to the SPS. The final section presents a general projection of insurance market reactions to the Satellite Power System.

None

1980-09-01

301

Remote Observing with the Keck Telescope Using the ACTS Satellite  

NASA Technical Reports Server (NTRS)

As a technical demonstration project for the NASA Advanced Communications Technology Satellite (ACTS), we have implemented remote observing on the 10-meter Keck II telescope on Mauna Kea in Hawaii from the California Institute of Technology campus in Pasadena. The data connection consists of optical fiber networks in Hawaii and California, connecting the end-points to high data rate (HDR) ACTS satellite antennae at JPL in Pasadena and at the Tripler Army Medical Center in Honolulu. The terrestrial fiber networks run the asynchronous transfer mode (ATM) protocol at DS-3 (45 Mbit/sec) speeds, providing ample bandwidth to enable remote observing with a software environment identical to that used for on-site observing in Hawaii. This experiment has explored the data requirements of remote observing with a modern research telescope and large-format detector arrays. While the maximum burst data rates are lower than those required for many other applications (e.g., HDTV), the network reliability and data integrity requirements are critical. As we show in this report, the former issue particularly may be the greatest challenge for satellite networks for this class of application. We have also experimented with the portability of standard TCP/IP applications to satellite networks, demonstrating the need for alternative TCP congestion algorithms and minimization of bit error rates (BER). Reliability issues aside, we have demonstrated that true remote observing over high-speed networks provides several important advantages over standard observing paradigms. Technical advantages of the high-speed network access include more rapid download of data to a user's home institution and the opportunity for alternative communication facilities between members of an observing team, such as audio- and videoconferencing.

Cohen, Judy; Shopbell, Patrick; Bergman, Larry

1998-01-01

302

Satellite aerosol observations for air quality: matching the scales of observations and applications  

NASA Astrophysics Data System (ADS)

The combination of satellite observations and numerical models of the atmosphere is a powerful tool for air quality studies. Satellite observations of aerosol optical depth and surface observations of particulate matter concentrations provide complementary views of particulate air quality, and methods are rapidly improving for using these observations together with the aid of atmospheric models. Advances in numerical modeling, together with increased computational power, have greatly improved the spatial resolution of atmospheric models. Air quality scientists have seized on these improvements, recognizing that important variation in pollution transport and air quality conditions can occur at very fine scales. But the scale and coverage of satellite resolutions make them very useful for some specific applications and less useful for others. The raw satellite observations used to retrieve properties of atmospheric aerosols have spatial resolution on the order of hundreds of meters, still finer than most numerical atmospheric models used for air quality. However, current aerosol retrievals require averaging over broader areas to achieve an acceptable signal-to-noise ratio, and steps taken to reduce uncertainty act to reduce the effective resolution of aerosol observations from satellite. This creates a complicated situation where the processing of the satellite data must balance observation accuracy and precision with the need to observe features at the scale appropriate to the problem. The Naval Research Laboratory has developed post-processors for satellite aerosol data that yield products suitable for initialization or validation of aerosol transport models; these post-processors are capable of generating output at a range of spatial resolutions. In this study, these products are used to examine the interaction between spatial averaging and observation uncertainty, and discuss how these tradeoffs affect specific air quality applications related to source characterization and exposure studies. This presentation concludes with a discussion of methods for extracting the optimal information content from the satellite observations for air quality studies at a range of spatial scales.

Hyer, E. J.; Reid, J. S.; Zhang, J.; Curtis, C. A.; Sessions, W. R.; Westphal, D. L.

2012-12-01

303

Automated surface observing systems  

NSF Publications Database

Title : Automated surface observing systems Type : Antarctic EAM NSF Org: OD / OPP Date : August 19 ... Action Memorandum (Installation of Automated Surface Observing Systems [ASOS}) To: Director, Office ...

304

Possible satellite-based observations of the 1997 Leonid meteoroids  

SciTech Connect

The Block IIA GPS satellites are equipped with a sensor designed to detect electromagnetic transients. Several phenomena will produce triggers in this sensor. They include earth-based electromagnetic transients such as lightning and two space-based phenomena--deep dielectric discharge and meteoroid or hyper-velocity micro-gram particle impact (HMPI). Energetic electrons in the GPS environment cause the deep dielectric charging. HMPIs cause triggers through the transient electric fields generated by the ejecta plasma. During the 1997 Leonid passage the energetic particle fluxes were very low. In the presence of such low fluxes the typical median trigger rate is 20 per minute with a standard deviation of about 20 per minute. Between 0800 UT and 1200 UT on November 17, 1997, the sensor on a specially configured satellite observed trigger rates more than 10 sigma above the nominal median rate. Sensors on other Block IIA GPS satellites also observed excess triggers during November. Detection is enhanced when the sensor antenna is oriented into the Leonid radiant. While many questions persist the authors feel that it is likely that the excess events during the November interval were caused by the close approach of the satellites to the Leonid meteoroid path.

Pongratz, M.B.; Carlos, R.C.; Cayton, T.

1998-12-01

305

Observations of artificially produced scintillations using satellite transmissions  

NASA Technical Reports Server (NTRS)

The ionospheric modification experiment, utilizing a high-powered transmitter, provides an opportunity to study ionospheric irregularities under relatively known conditions. The irregularities were studied by means of transionospheric signals from the polar-orbiting satellite ESSA 8 transmitting at 137 MHz. These observations show that scintillations occur when the satellite to ground station geometry is such that the ray from the satellite passes through the region in the ionosphere under modification. In general, a cut across the illuminated volume is obtained; thus an active region of about 100 km in diameter is indicated. For the most part, the artificial scintillations appear to be similar to those obtained from naturally occurring irregularities, but a systematic change from 3 to 1 sec in the fluctuation period is usually observed as the satellite traverses from the northern to the southern portions of the active region. The change in period appears to be produced by a systematic change in irregularity scale size from about 4 to about 1 km.

Pope, J. H.; Fritz, R. B.

1974-01-01

306

Stratocumulus cloud height variations determined from surface and satellite observations  

NASA Technical Reports Server (NTRS)

Determination of cloud-top heights from satellite-inferred cloud-top temperatures is a relatively straightforward procedure for a well-behaved troposphere. The assumption of a monotonically decreasing temperature with increasing altitude is commonly used to assign a height to a given cloud-top temperature. In the hybrid bispectral threshold method, or HBTM, Minnis et al. (1987) assume that the lapse rate for the troposphere is -6.5/Kkm and that the surface temperature which calibrated this lapse rate is the 24 hour mean of the observed or modeled clear-sky, equivalent blackbody temperature. The International Satellite Cloud Climatology Project (ISCCP) algorithm (Rossow et al., 1988) attempts a more realistic assignment of height by utilizing interpolations of analyzed temperature fields from the National Meteorological Center (NMC) to determine the temperature at a given level over the region of interest. Neither these nor other techniques have been tested to any useful extent. The First ISCCP Regional Experiment (FIRE) Intensive Field Observations (IFO) provide an excellent opportunity to assess satellite-derived cloud height results because of the availability of both direct and indirect cloud-top altitude data of known accuracy. The variations of cloud-top altitude during the Marine Stratocumulus IFO (MSIFO, June 29 to July 19, 1987) derived from surface, aircraft, and satellite data are examined.

Minnis, Patrick; Young, David F.; Davies, R.; Blaskovic, M.; Albrecht, Bruce A.

1990-01-01

307

Evolution of Close Binary Systems: Observational Aspects.  

National Technical Information Service (NTIS)

Detached close binary systems define the main sequence band satisfactorily, but very little is known about the masses of giants and supergiants. High dispersion international ultraviolet explorer satellite observations promise an improvement, since blue c...

M. J. Plavec

1981-01-01

308

Mature systems for small satellite missions  

NASA Astrophysics Data System (ADS)

Over the past several years Satellites International has developed an integrated suite of satellite sub-systems and small satellite buses. The sub-systems include S-band communications, attitude sensing and control, power conversion and distribution, and on-board data handling. They are inherently modular and readily adaptable to different satellite configurations, a concept known as semi-standardisation. This concept has been adopted by two generic low-cost buses: MicroSIL for satellites in the mass range 40-80kg; and MiniSIL for satellites in the range 100-500kg. Their architecture is based on the semi-standard sub-systems, but easily modified to utilise sub-systems from other manufacturers. They can support all stabilisation methods including spinning, 3-axis control and gravity gradient and are adaptable to a wide variety of missions including Earth resources, scientific, communications and technology demonstration. The Company also manufactures a range of low cost ground support equipment and complete ground stations to complement the space-borne systems.

Ward, A. Kim; Barrington-Brown, A. James; Gardner, Stephen J.

1996-11-01

309

Millimeter-wave personal satellite communication system  

NASA Astrophysics Data System (ADS)

This paper describes the system concept of a millimeter-wave personal satellite communication, which includes the configuration of the communication system, the satellite system, and the earth terminal system. The system has a large channel capacity and achieves high performance through a flexible channel set-up method, efficient frequency reuse, and onboard communication equipment such as a baseband channel switching processor and a modulator and demodulator (Modem). Two examples of communication systems are shown, in which the information bit rate, the number of multi-beams, and the antenna diameters are different. On the assumption that a 2 ton class satellite will be used, rough estimates are made of the size, weight, and power consumption of the onboard communication system and bus system of the satellite. In addition, details are given regarding the specifications and performance of trial productions of communication equipment such as the switching processor, the Modem, the TWTA, and the LNA. Finally, the key technical issues for establishing a millimeter-wave personal satellite communication system are also discussed.

Kashiki, Kanshiro; Kuri, Takaki; Maruyama, Hideyuki; Kikuchi, Takaaki; Yamamoto, Tetsuo

1993-10-01

310

Millimeter-wave personal satellite communication system  

NASA Astrophysics Data System (ADS)

This paper describes the system concept of a millimeter-wave personal satellite communication, which includes the configuration of the communication system, the satellite system, and the earth terminal system. The system has a large channel capacity and achieves high performance through a flexible channel set-up method, efficient frequency reuse, and onboard communication equipment such as a baseband channel switching processor and a modulator and demodulator (Modem). Two examples of communication systems are shown, in which the information bit rate, the number of multi-beams, and the antenna diameters are different. On the assumption that a 2 ton class satellite will be used, rough estimates are made of the size, weight, and power consumption of the onboard communication system and bus system of the satellite. In addition, details are given regarding the specifications and performance of trial productions of communication equipment such as the switching processor, the Modem, the TWTA, and the LNA. Finally, the key technical issues for establishing a millimeter-wave personal satellite communication system are also discussed.

Kashiki, Kanshiro; Kuri, Takaki; Maruyama, Hideyuki; Kikuchi, Takaaki; Yamamoto, Tetsuo

311

ECC Ozonesonde Reliability, Observations, and Comparisons with Satellite Ozone Instruments  

NASA Technical Reports Server (NTRS)

Electrochemical Concentration Cell (ECC) ozone instruments depend on the quality of care exercised in their pre-flight preparation. The ozone-measuring project conducted at Goddard Space Flight Center's Wallops Flight Facility uses a number of mechanisms designed to inspect the ECC for anomalies that may interfere with the reception of valid ozone profiles. Complete electronic testing of the instrument, individually and when coupled to its radiosonde has led to exceptional monitoring of ozone for detecting long-term atmospheric changes. A number of factors are considered when preparing an ECC instrument for flight. These basically are specific calibrations of pump efficiency, volumetric flow rate, temperature of the air entering the pump, and background current. The concentration of the potassium iodide solution is also important. Wallops is the only site using a UV photometer (Dasibi) to compare ECC ozone output at various concentrations of ozone that allows adjustment to be made to offsets that may appear in the balloon-borne instrument prior to release. All of the above procedures allow identification of potential problems before release of the ECC instrument. Procedures followed at Wallops also are employed in Brazil, and Ascension Island where NASA has cooperative agreements in place to obtain ozonesondes data. All ECC instruments are prepared 3-4 weeks prior to the day of observation. We will briefly describe the instrumental tests employed. These tests have included simultaneous dual observations to compare the effect of different solution concentrations, comparison of sensors of different manufacturers, and comparisons with surface- and space-based instrumentation such as the Dobson Spectrophotometer and satellites. Vertical profiles of ozone from Arctic, mid-latitudes, and Antarctica will be discussed. Although not unusual, the data reveals ozone structure that correlate well with typical atmospheric temperatures and possibly relative humidity. Finally, vertical ozone distribution, compared with remotely measured ozone from lidar and satellite, will be discussed. Specific comparisons between ECC and HALOE measurements, integrated ECC total ozone overburden with the EP-TOMS and the Dobson, as well as comparisons with lidar are discussed. Results show agreement and some disagreement between the in situ measurements of the ECC and the remote instruments. We postulate reasons for the differences, or biases, which in spite of the excellent ECC quality control during pre-flight preparation and data analysis processes, may be due to uncertainties in both measuring systems.

Schmidlin, F. J.; Northam, E. T.; Ross, E. D.; Schauer, A. G.; Gerlach, John C. (Technical Monitor)

2001-01-01

312

A land mobile satellite data system  

NASA Astrophysics Data System (ADS)

The Telesat Mobile Incorporated (TMI) Mobile Data System (MDS) was developed to apply satellite technology to the transportation industry's requirement for a fleet management system. It will provide two-way messaging and automatic position reporting capabilities between dispatch centers and customers' fleets of trucks. The design was based on the Inmarsat L-Band space segment with system link parameters and margins adjusted to meet the land mobile satellite channel characteristics. The system interfaces with the Teleglobe Des Laurentides earth station at Weir, Quebec. The signaling protocols were derived from the Inmarsat Standard C packet signalling system with unique trucking requirements incorporated where necessary.

Kent, John D. B.

313

A land mobile satellite data system  

NASA Technical Reports Server (NTRS)

The Telesat Mobile Incorporated (TMI) Mobile Data System (MDS) was developed to apply satellite technology to the transportation industry's requirement for a fleet management system. It will provide two-way messaging and automatic position reporting capabilities between dispatch centers and customers' fleets of trucks. The design was based on the Inmarsat L-Band space segment with system link parameters and margins adjusted to meet the land mobile satellite channel characteristics. The system interfaces with the Teleglobe Des Laurentides earth station at Weir, Quebec. The signaling protocols were derived from the Inmarsat Standard C packet signalling system with unique trucking requirements incorporated where necessary.

Kent, John D. B.

1990-01-01

314

Analysis of maritime mobile satellite communication systems  

NASA Astrophysics Data System (ADS)

The communication channel between a satellite and a ship earth station (SES) is described by a model which includes multipath fading, Doppler shift and noise. Multipath fading is caused by reflections from the sea surface. These reflections can affect the system performance, especially at low elevation angles or when SES is using low gain antennas. Doppler shift is a very important effect when using low altitude satellites, because of the high velocities involved. A software simulator is described and a simulator is presented for multipath fading in the maritime communications environment. Analysis of throughput of an unslotted Aloha maritime mobile satellite communication channel is also presented.

Zapata, Augusto J.

1988-12-01

315

Instrumentation for Spacecraft-to-Spacecraft Radio Science Observations of Jupiter and Satellites  

Microsoft Academic Search

Investigations of planetary atmospheres and surfaces via radio occultation and scattering techniques have been successfully conducted on many planets and several large satellites in the solar system using one-way downlink from a spacecraft to a ground station. Limitations on the received SNR or geometrical coverage can be overcome with alternate observation configurations. Uplink observations where a signal is transmitted from

Sami Asmar; W. Folkner; D. Hinson; L. Iess; I. Linscott; E. Marouf; P. Tortora

2010-01-01

316

The Ellipso (TM) mobile satellite system  

NASA Technical Reports Server (NTRS)

The Ellipso(trademark) Mobile Satellite System is conceived to extend telecommunication services throughout the world to users that are not well, or not at all served by existing mobile or fixed telephone systems. Unlike cellular telephones, Ellipso(trademark) offers fully nationwide service to every served country, thereby providing service to users located anywhere within the national boundaries, no matter how isolated or remote. With Ellipso(trademark), a user in the middle of a wilderness area will have the same mobile telecommunications service as a user in a major metropolitan area. Ellipso(trademark) uses medium earth orbiting (MEO) satellites and an efficient system design to reach its subscribers directly and at a price that is competitive with terrestrial telephone services. The subscriber only requires a clear view of a serving satellite to achieve a connection and to connect to anyone else served by the national telecommunications system. Subscribers within view of two or more satellites will benefit from Ellipso's(trademark) unique satellite diversity processing, using all available satellites simultaneously to optimize circuit quality.

Castiel, David; Draim, John E.

1995-01-01

317

Geosynchronous satellite systems design considerations and optimization methodology  

Microsoft Academic Search

In this paper, various aspects of satellite communications systems are discussed. First, the new satellite services and their operating frequency bands are identified. This is followed by the lessons learned from the recent satellite system ventures. Also, various enabling technologies, required to introduce an array of satellite services, are examined, and some innovative satellite design considerations are looked into. Finally,

Ali Grami

2005-01-01

318

Observations of RR Lyrae with the ANS satellite  

NASA Technical Reports Server (NTRS)

Photometric observations of RR Lyr in the ultraviolet have been obtained using the Astronomical Netherlands Satellite. The observations are compared with theoretical light curves calculated using synthetic spectra and angular diameters determined as a function of phase for RR Lyr by Manduca et al. from photometry at longer wavelengths. A good agreement is found. A bump in the observed light curves in the phase range 0.6 to 0.8 supports the existence of a shock as predicted by Hutchinson, Hill, and Lillie.

Bonnell, J.; Wu, C.-C.; Bell, R. A.; Hutchinson, J. L.

1982-01-01

319

Satellite observations of the global distribution of stratospheric ozone  

NASA Technical Reports Server (NTRS)

Observations of backscattered radiation from an orbiting geophysical observatory (Ogo) satellite for the period September 1967 to February 1968 have been used to determine the global distribution of ozone at different levels in the middle and upper stratosphere (30-55 km). The derived distributions show significant seasonal and geographic variations with important differences indicated between winter and summer hemisphere distributions. The Ogo-derived distributions are compared with other observations (rocket and satellite) and with photochemical calculations. It is suggested that the increased ozone mixing ratio in the high-latitude winter hemisphere can be accounted for by transport processes up to about 40-45 km and by temperature-sensitive chemistry above.

London, J.; Frederick, J. E.

1977-01-01

320

CCD astrometric observations of Uranian satellites: 1995-1998  

NASA Astrophysics Data System (ADS)

Astrometric positions of the five largest Uranian satellites from 750 CCD frames taken at the oppositions of 1995 through 1998 are presented. The images were obtained over 35 nights. Observed positions are compared with the calculated positions from GUST86. The standard deviations are better than 0farcs 05 for the four largest satellites and 0farcs 08 for Miranda. Based on observations made at Laboratório Nacional de Astrofísica/CNPq/MCT-Itajubá-Brazil. Please Send offprint requests to C.H. Veiga. Table 1 is only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/Abstract.html

Veiga, C. H.; Vieira Martins, R.

1999-08-01

321

SOFT project: a new forecasting system based on satellite data  

NASA Astrophysics Data System (ADS)

The aim of the SOFT project is to develop a new ocean forecasting system by using a combination of satellite dat, evolutionary programming and numerical ocean models. To achieve this objective two steps are proved: (1) to obtain an accurate ocean forecasting system using genetic algorithms based on satellite data; and (2) to integrate the above new system into existing deterministic numerical models. Evolutionary programming will be employed to build 'intelligent' systems that, learning form the past ocean variability and considering the present ocean state, will be able to infer near future ocean conditions. Validation of the forecast skill will be carried out by comparing the forecasts fields with satellite and in situ observations. Validation with satellite observations will provide the expected errors in the forecasting system. Validation with in situ data will indicate the capabilities of the satellite based forecast information to improve the performance of the numerical ocean models. This later validation will be accomplished considering in situ measurements in a specific oceanographic area at two different periods of time. The first set of observations will be employed to feed the hybrid systems while the second set will be used to validate the hybrid and traditional numerical model results.

Pascual, Ananda; Orfila, A.; Alvarez, Alberto; Hernandez, E.; Gomis, D.; Barth, Alexander; Tintore, Joaquim

2002-01-01

322

First UV satellite observations of mesospheric water vapor  

Microsoft Academic Search

We report the first UV satellite observations of mesospheric water vapor. The measurements are of nonthermal OH prompt emission between 300-330 nm produced directly from the photodissociation of water vapor by H Lyman-alpha. This technique is most sensitive to water vapor concentrations between 70-90 km altitude. We present OH data from two limb scanning experiments: the Middle Atmosphere High Resolution

Michael H. Stevens; R. L. Gattinger; J. Gumbel; E. J. Llewellyn; D. A. Degenstein; M. Khaplanov; G. Witt

2008-01-01

323

Observations of the mutual phenomena of Saturnian satellites in 1980  

NASA Astrophysics Data System (ADS)

Sinclair's (1977) theory is used in a preliminary orbital analysis of five mutual phenomena of the Saturnian satellites in 1980. Midtimes and light losses (normalized to unity) of the events determined from the observed light curves are given, together with calculations made with the orbital elements obtained. In order to check the present computer calculations, results have been compared with the predictions of Aksnes and Franklin (1978), in which substantially the same orbital elements are used.

Soma, M.; Nakamura, T.

1982-06-01

324

Improving National Air Quality Forecasts with Satellite Aerosol Observations  

Microsoft Academic Search

Accurate air quality forecasts can allow for mitigation of the health risks associated with high levels of air pollution. During September 2003, a team of NASA, NOAA, and EPA researchers demonstrated a prototype tool for improving fine particulate matter (PM2.5) air quality forecasts using satellite aerosol observations. Daily forecast products were generated from a near-real-time fusion of multiple input data

Jassim Al-Saadi; James Szykman; R. Bradley Pierce; Chieko Kittaka; Doreen Neil; D. Allen Chu; Lorraine Remer; Liam Gumley; Elaine Prins; Lewis Weinstock; Clinton MacDonald; Richard Wayland; Fred Dimmick; Jack Fishman

2005-01-01

325

Satellite observations of lightning-induced electron precipitation  

Microsoft Academic Search

Lightning-induced electron precipitation (LEP) from the Earth's radiation belt has been observed on numerous occasions with detectors on the low-altitude S81-1\\/SEEP satellite. A sequence of seven LEP events on September 9, 1982, and eight events on October 20, 1982, are correlated on a one-to-one basis with one-hop whistlers at Palmer, Antarctica. The temporal profile within a LEP burst has a

H. D. Voss; M. Walt; W. L. Imhof; J. Mobilia

1998-01-01

326

Critical areas: Satellite power systems concepts  

NASA Technical Reports Server (NTRS)

Critical Areas are defined and discussed in the various areas pertinent to satellite power systems. The presentation is grouped into five areas (General, Space Systems, Solar Energy Conversion, Microwave Systems, and Environment/Ecology) with a sixth area (Power Relay) considered separately in an appendix. Areas for Future Consideration as critical areas are discussed in a second appendix.

1975-01-01

327

Satellite power system salvage and disposal alternatives  

NASA Technical Reports Server (NTRS)

A wide range of salvage options for the SPS satellite, ranging from use in and beyond geosynchronous orbit to use in low Earth orbit in return and use on Earth are presented. The satellite can be used intact to provide power for various purposes, it can be cannibalized or it can be melted down to supply materials for space or ground based products. The use of SPS beyond its nominal lifetime provides value that can be deducted from the SPS capital investment cost. The present value of the salvage value of the SPS satellites, referenced to the system initial operation data, is on the order of five to ten percent of its on-orbit capital cost. (Given a 30 year satellite lifetime and a four percent discount rate, the theoretical maximum salvage value is 30.8 percent of the capital cost.) The SPS demonstration satellite is available some 30 years earlier than the first full scale SPS satellite and has a salvage value on the order of 80 percent of its on-orbit capital cost. In the event that it becomes desirable to dispose of either the demonstration of full scale SPS satellite, a number of disposal options is presented for which intact disposal costs are less than one percent of capital costs.

1980-01-01

328

Polarimetric observations of the Galilean satellites near opposition in 2011  

NASA Astrophysics Data System (ADS)

We present results of the new polarimetric observations of the Galilean satellites Io, Ganymede, Europe, and Callisto carried out on October 21 - November 1, 2011. We used 1.25m telescope equipped with the UBVRI double image chopping photoelectric polarimeter, 2.6m Shain telescope equipped with a one-channel photoelectric photometer-polarimeter, 1m RCC telescope equipped with a one-channel photoelectric photometer-polarimeter (Crimean Astrophysical Observatory, Ukraine), and 0.7m telescope equipped with a one-channel photoelectric photometer-polarimeter (Chuguev Observational Station of Astronomical Institute of Karazin Kharkiv National University, Ukraine). The measurements were performed at phase angles ranging from 0.34° to 2.12°. Our new observations fully confirmed the presence of the polarization opposition effect for high-albedo satellites Io, Europa, and Ganymede at phase angles less than 2°. Within the accuracy of the measurements we did not detect the polarization opposition effect for moderate-albedo satellite Callisto.

Zaitsev, S. V.; Kiselev, N. N.; Rosenbush, V. K.; Velichko, F. P.; Kolesnikov, S. V.; Antonyuk, K. A.; Psarev, V. N.

2012-11-01

329

Odyssey, an optimized personal communications satellite system  

NASA Astrophysics Data System (ADS)

Personal communications places severe demands on service providers and transmission facilities. Customers are not satisfied with the current levels of service and want improvements. Among the characteristics that users seek are: lower service rates, hand held convenience, acceptable time delays, ubiquitous service, high availability, reliability, and high quality. The space industry in developing commercial space systems for providing mobile communications to personal telephones. Provision of land mobile satellite service is fundamentally different from the fixed satellite service provided by geostationary satellites. In fixed service, the earth based antennas can depend on a clear path from user to satellite. Mobile users in a terrestrial environment commonly encounter blockage due to vegetation, terrain or buildings. Consequently, high elevation angles are of premium value. TRW studied the issues and concluded that a Medium Earth Orbit constellation is the best solution for Personal Communications Satellite Service. TRW has developed Odyssey, which uses twelve satellites in medium altitude orbit to provide personal communications satellite service. The Odyssey communications system projects a multibeam antenna pattern to the Earth. The attitude control system orients the satellites to ensure constant coverage of land mass and coastal areas. Pointing can be reprogrammed by ground control to ensure optimized coverage of the desired service areas. The payload architecture features non-processing, 'bent pipe' transponders and matrix amplifiers to ensure dynamic power delivery to high demand areas. Circuit capacity is 3000 circuits per satellite. Each satellite weighs 1917 kg (4226 pounds) at launch and the solar arrays provide 3126 watts of power. Satellites are launched in pairs on Ariane, Atlas, or other vehicles. Each satellite is placed in a circular orbit at an altitude of 10,354 km. satellites permits phased introduction of service. After only three launches, in which two satellites are launched into each plane, continuous service can be provided to most of the world. After three more launches for a total of 12 satellites, service can be expanded to all populated regions of the Earth with path diversity to most regions. *The Odyssey system is superior to both geostationary satellites and low earth orbiting satellites. -Odyssey provides many benefits to the end user which are described in the paper. These include: low cost, convenience, high availability, reliability, and acceptable time delay. Odyssey exhibits benefits for telecommunications operators: simple operations, incremental, phased startup, long space segment life-time, high profitability, dynamic flexibility for adjustment and short time to market. %Since submission of an FCC application in 1991, TRW has continued to explore ways to further improve the Odyssey approach by expanding coverage to the entire world and reducing the initial investment while maintaining high quality service.

Rusch, Roger J.

330

The Saturn System's Icy Satellites: New Results from Cassini  

NASA Technical Reports Server (NTRS)

Cassini-Huygens is a multidisciplinary, international planetary mission consisting of an orbiting spacecraft and a probe. The Huygens probe successfully landed on Titan's surface on January 14, 2005, while the orbiter has performed observations of Saturn, its rings, satellites, and magnetosphere since it entered orbit around Saturn on July 1, 2004. The Cassini mission has been prolific in its scientific discoveries about the Saturn system. In this special section, we present new mission results with a focus on the 'icy satellites,' which we define as all Saturn's moons with the exception of Titan. The results included in this section have come out of the Cassini SOST--Satellites Orbiter Science Team--a multi-instrument and multidiscipline group that works together to better understand the icy satellites and their interactions with Saturn and its rings. Other papers included in this issue present ground-based observations and interior modeling of these icy moons.

Lopes-Gautier, Rosaly M.; Buratti, Bonnie; Hendrix, A. R.

2008-01-01

331

Meteosat Third Generation (MTG) Development in the Context of Other Future Geostationary Satellite Observations  

NASA Astrophysics Data System (ADS)

Meteosat Third Generation (MTG) will provide continuity to the European Meteosat observations which are currently performed with Meteosat Second Generation (MSG). MSG takes images in 12 channels with a repeat rate of 15 minutes for the full disk. The future MTG satellites will expand the capabilities far beyond those of MSG with an enhanced imager (FCI) which has 16 channels and a 10 minutes repeat cycle for taking images of the earth's full disk. Especially the novel instruments on MTG a) Lightning Imager (LI), hyperspectral InfraRed Sounder (IRS) and the Ultraviolet-Visible-Near infrared spectrometer (UVN) will provide unprecedented observations. The four instruments will fly on two types of satellites, the imaging satellites (MTG-I) carrying the FCI and LI, and the sounding satellites (MTG-S) carrying the IRS and UVN. The UVN instrument is provided by the European Space Agency (ESA) and the European GMES (Global Monitoring and Environmental Security) programme. The first launch of an imaging satellite is foreseen for 2017. In total the MTG series will serve us with four MTG-I and two MTG-S satellites for about two decades. MTG has been defined to meet the requirements of the user community, i.e. mainly users in Europe. However an interesting perspective is to see the development of the European MTG satellite system in the context of the evolution of the global space-based meteorological satellite system, notably those from geostationary orbit. Satellite agencies in the US, Japan, China and Europe will fly advanced imagers comparable to the FCI on MTG. Therefore there is also scope for a common evolution of the applications of the observations which is being addressed inter alia by CGMS (Coordination Group for Meteorological Satellites). Various agencies will also realise lightning observations from space. Other instruments on MTG (IRS and UVN) can be seen as pioneering realisations in a geostationary orbit of measurements known from polar orbits. This step into the geostationary orbit will enable a high temporal repeat cycle of the observations. For water vapour this means that for the first time observations from space are being made with a temporal resolution commensurate with the spatial resolution. The presentation will present the status of the instrument and applications development. It will also highlight the current cooperation opportunities created by the similarity of the future observing systems.

Schmetz, J.; Stuhlmann, R.; Grandell, J.; Tjemkes, S.; Calbet, X.; Koenig, M.; Rota, S.

2012-12-01

332

Design and evaluation of control systems for large communications satellites  

NASA Technical Reports Server (NTRS)

Control techniques for future large flexible spacecraft are developed. Control design and analysis are supported by a comprehensive CAD system. The proposed operational mobile communications satellite (OMSAT) featuring a 44 m offset fed antenna is used as target application. Requirements for satellite attitude control and communications beam pointing are defined. The following control methods are applied to the system: standard linear optimal regulator (LOR) with Luenberger observer, LOR/observer with selective spill-over suppression, frequency shaped LOR, LOR with closed-loop order reduction by cost decoupling, and robust servomechanism.

Steiber, M. E.

1985-01-01

333

Population of asteroids with satellites in the Solar system  

NASA Astrophysics Data System (ADS)

The decision of fundamental problems of the origin and evolution of the solar system requires a comprehensive research of asteroids. The last decade is marked by numerous discoveries of satellites of asteroids. The investigation of these satellites gives: a) the possibility to determine masses, densities and other physical characteristics of asteroids with higher precision; b) some information for development of means of protection of the Earth from collision with an asteroid and also for planning and progression of flights to asteroids with the purposes of their scientific research and use of their natural resources for needs of mankind. We give the observational data on the known satellite systems. The methods for detection and investigation of their basic characteristics, probable mechanisms of formation of satellites of asteroids, and stability of their movement are described.

Prokof'eva, V. V.; Batrakov, Yu. V.; Karachkina, L. G.

2005-10-01

334

Land-mobile satellite communication system  

NASA Technical Reports Server (NTRS)

A satellite communications system includes an orbiting communications satellite for relaying communications to and from a plurality of ground stations, and a network management center for making connections via the satellite between the ground stations in response to connection requests received via the satellite from the ground stations, the network management center being configured to provide both open-end service and closed-end service. The network management center of one embodiment is configured to provides both types of service according to a predefined channel access protocol that enables the ground stations to request the type of service desired. The channel access protocol may be configured to adaptively allocate channels to open-end service and closed-end service according to changes in the traffic pattern and include a free-access tree algorithm that coordinates collision resolution among the ground stations.

Yan, Tsun-Yee (Inventor); Rafferty, William (Inventor); Dessouky, Khaled I. (Inventor); Wang, Charles C. (Inventor); Cheng, Unjeng (Inventor)

1993-01-01

335

Future satellite systems - Market demand assessment  

NASA Technical Reports Server (NTRS)

During 1979-80, a market study was performed regarding the future total demand for communications services, and satellite transmission service at the 4/6 GHz, 12/14 GHz, and 20/30 GHz frequencies. Included in the study were a variety of communications traffic characteristics as well as projections of the cost of C and Ku band satellite systems through the year 2000. In connection with the considered study, a total of 15 major study tasks and subtasks were undertaken and were all interrelated in various ways. The telecommunications service forecasts were concerned with a total of 21 data services, 5 voice services, and 5 video services. The traffic volumes within the U.S. for the three basic services were projected for three time periods. It is found that the fixed frequency allocation for domestic satellites combined with potential interference from adjacent satellites means a near term lack of orbital positions above the U.S.

Reiner, P. S.

1981-01-01

336

Introduction to Global Navigation Satellite System  

NASA Technical Reports Server (NTRS)

This viewgraph presentation reviews the fundamentals of satellite navigation, and specifically how GPS works. It presents an overview and status of Global Positioning System, for both the current GPS, and plans to modernize it in the future. There is also a overview and status of other Global Navigation Satellite System (GNSS), specifically GLONASS, Galileo, and QZSS. There is also a review of Satellite based time transfer techniques. The topic is of interest to the Time and Frequency Community, because the Global Positioning system has become the primary system for distributing Time and frequency globally, and because it allows users to synchronize clocks and calibrate and control oscillators in any location that has a GPS antenna.

Moreau, Michael

2005-01-01

337

Optimizing space constellations for mobile satellite systems  

NASA Technical Reports Server (NTRS)

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.

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

1993-01-01

338

Solar power satellite, system definition study. Part 2, volume 3: SPS satellite systems  

NASA Technical Reports Server (NTRS)

The differences in approach to solar energy conversion by solar cells and thermal engine systems are examined. Systems requirements for the solar power satellite (SPS) are given along with a description of the primary subsystems. Trades leading to exact configuration selection, for example, selection of the Rankine cycle operating temperatures are explained, and two satellite configurations are discussed.

1977-01-01

339

National Trends in Satellite Observed Lighting: 1992-2009  

NASA Astrophysics Data System (ADS)

A time series of global annual satellite maps of nighttime lights reveals several distinct patterns linked to population changes, economic development and the improvements in lighting efficiency. Six categories of national lighting trends have been defined: 1) Rapid growth in lighting driven by population and economic growth, 2) Population driven changes in nighttime lights, 3) Economic driven changes in nighttime lights, 4) Erratic, with wide interannual variation in nighttime lights and little affinity to population and economic changes, 5) Stable, with little change over time and little affinity to population and economic changes, and 6) Transitional countries not fitting in to the other five classes, in many cases due to a shift from one class to another midway through the time series. The results indicate that there are national level differences in the behavior of nighttime lights over time. Recognition of these patterns may lead to improved spatial modeling of socioeconomic processes based on satellite observed nighttime lights.

Elvidge, C. D.; Sutton, P. C.; Baugh, K.; Ziskin, D. C.; Ghosh, T.; Anderson, S.

2011-12-01

340

A Comparison of Techniques for Scheduling Earth-Observing Satellites  

NASA Technical Reports Server (NTRS)

Scheduling observations by coordinated fleets of Earth Observing Satellites (EOS) involves large search spaces, complex constraints and poorly understood bottlenecks, conditions where evolutionary and related algorithms are often effective. However, there are many such algorithms and the best one to use is not clear. Here we compare multiple variants of the genetic algorithm: stochastic hill climbing, simulated annealing, squeaky wheel optimization and iterated sampling on ten realistically-sized EOS scheduling problems. Schedules are represented by a permutation (non-temperal ordering) of the observation requests. A simple deterministic scheduler assigns times and resources to each observation request in the order indicated by the permutation, discarding those that violate the constraints created by previously scheduled observations. Simulated annealing performs best. Random mutation outperform a more 'intelligent' mutator. Furthermore, the best mutator, by a small margin, was a novel approach we call temperature dependent random sampling that makes large changes in the early stages of evolution and smaller changes towards the end of search.

Globus, Al; Crawford, James; Lohn, Jason; Pryor, Anna

2004-01-01

341

Tropical convective systems life cycle characteristics from geostationary satellite and precipitating estimates derived from TRMM and ground weather radar observations for the West African and South American regions  

NASA Astrophysics Data System (ADS)

In the tropics most of the rainfall comes in the form of individual storm events embedded in the synoptic circulations (e.g., monsoons). Understanding the rainfall and its variability hence requires to document these highly contributing tropical convective systems (MCS). Our knowledge of the MCS life cycle, from a physical point of view mainly arises from individual observational campaigns heavily based on ground radar observations. While this large part of observations enabled the creation of conceptual models of MCS life cycle, it nevertheless does not reach any statistically significant integrated perspective yet. To overcome this limitation, a composite technique, that will serve as a Day-1 algorithm for the Megha-Tropiques mission, is considered in this study. this method is based on a collocation in space and time of the level-2 rainfall estimates (BRAIN) derived from the TMI radiometer onboard TRMM with the cloud systems identified by a new MCS tracking algorithm called TOOCAN and based on a 3-dimensional segmentation (image + time) of the geostationary IR imagery. To complete this study, a similar method is also developed collocating the cloud systems with the precipitating features derived from the ground weather radar which has been deployed during the CHUVA campaign over several Brazilian regions from 2010 up to now. A comparison of the MCSs life cycle is then performed for the 2010-2012 summer seasons over the West African, and South American regions. On the whole region of study, the results show that the temporal evolution of the cold cloud shield associated to MCSs describes a symmetry between the growth and the decay phases. It is also shown that the parameters of the conceptual model of MCSs are strongly correlated, reducing thereby the problem to a single degree of freedom. At the system scale, over both land and oceanic regions, rainfall is described by an increase at the beginning (the first third) of the life cycle and then smoothly decreases as the system shrinks and dissipates. The evolutions of the precipitating properties associated to MCSs indicate that the life cycle of these systems can be described by three phases: initiation, mature and dissipation. This pattern is robust across the entire monsoonal region and the scale factors of this idealized model indicate complex regional specificities.

Fiolleau, T.; Roca, R.; Angelis, F. C.; Viltard, N.

2012-12-01

342

Orbit determination accuracies using satellite-to-satellite tracking. [applicable to the Tracking and Data Relay Satellite system  

NASA Technical Reports Server (NTRS)

The results of the ATS-6/GEOS-3 and the ATS-6/NIMBUS-6 satellite-to-satellite tracking orbit determination experiments are reported. The tracking systems used in these experiments differ from the Tracking and Data Relay Satellite System (TDRSS), primarily in the use of one rather than two synchronous relay satellites. However, the simulations mentioned indicate that the insights gained from the experiments with regard to proper data reduction techniques and expected results are applicable to the TDRSS.

Vonbun, F. O.; Argentiero, P. D.; Schmid, P. E.

1978-01-01

343

Improving a Spectral Bin Microphysical Scheme Using TRMM Satellite Observations  

NASA Technical Reports Server (NTRS)

Comparisons between cloud model simulations and observations are crucial in validating model performance and improving physical processes represented in the mod Tel.hese modeled physical processes are idealized representations and almost always have large rooms for improvements. In this study, we use data from two different sensors onboard TRMM (Tropical Rainfall Measurement Mission) satellite to improve the microphysical scheme in the Goddard Cumulus Ensemble (GCE) model. TRMM observed mature-stage squall lines during late spring, early summer in central US over a 9-year period are compiled and compared with a case simulation by GCE model. A unique aspect of the GCE model is that it has a state-of-the-art spectral bin microphysical scheme, which uses 33 different bins to represent particle size distribution of each of the seven hydrometeor species. A forward radiative transfer model calculates TRMM Precipitation Radar (PR) reflectivity and TRMM Microwave Imager (TMI) 85 GHz brightness temperatures from simulated particle size distributions. Comparisons between model outputs and observations reveal that the model overestimates sizes of snow/aggregates in the stratiform region of the squall line. After adjusting temperature-dependent collection coefficients among ice-phase particles, PR comparisons become good while TMI comparisons worsen. Further investigations show that the partitioning between graupel (a high-density form of aggregate), and snow (a low-density form of aggregate) needs to be adjusted in order to have good comparisons in both PR reflectivity and TMI brightness temperature. This study shows that long-term satellite observations, especially those with multiple sensors, can be very useful in constraining model microphysics. It is also the first study in validating and improving a sophisticated spectral bin microphysical scheme according to long-term satellite observations.

Li, Xiaowen; Tao, Wei-Kuo; Matsui, Toshihisa; Liu, Chuntao; Masunaga, Hirohiko

2010-01-01

344

A performance analysis of the IRIDIUM® low earth orbit satellite system with a degraded satellite constellation  

Microsoft Academic Search

There are currently several commercial Low Earth Orbit (LEO) satellite systems under development that will provide worldwide voice, data, facsimile, and paging services. This article presents a performance analysis of the IRIDIUM® LEO satellite system, as several satellites become non-operational. The analysis is conducted using a computer simulation of the system. First, it examines the system's capability to meet real-time

Carl E. Fossa; Richard A. Raines; Gregg H. Gunsch; Michael A. Temple

1998-01-01

345

Multi-satellite aerosol observations in the vicinity of clouds  

NASA Astrophysics Data System (ADS)

Improved characterization of aerosol properties in the vicinity of clouds is important for better understanding two critical aspects of climate: aerosol-cloud interactions and the direct radiative effect of aerosols. Satellite measurements have provided important insights into aerosol properties near clouds, but also suggested that the observations can be affected by 3-D radiative processes and instrument blurring not considered in current data interpretation methods. This study examines systematic cloud-related changes in particle properties and radiation fields that influence satellite measurements of aerosols in the vicinity of low-level maritime clouds. For this, the paper presents a statistical analysis of a yearlong global dataset of co-located MODIS and CALIOP observations and theoretical simulations. The results reveal that CALIOP-observed aerosol particle size and optical thickness, and MODIS-observed solar reflectance increase systematically in a wide transition zone around clouds. It is estimated that near-cloud changes in particle populations - including both aerosols and undetected cloud particles - are responsible for roughly two thirds of the observed increase in 0.55 ?m MODIS reflectance. The results also indicate that 3-D radiative processes significantly contribute to near-cloud reflectance enhancements, while instrument blurring contributes significantly only within 1 km from clouds and then quickly diminishes with distance from clouds.

Várnai, T.; Marshak, A.; Yang, W.

2013-04-01

346

A satellite communications system for electric utilities  

NASA Technical Reports Server (NTRS)

This paper presents the results of a study into the feasibility of using satellite communications for a country-wide system of electric distribution system monitoring and control. The concept selected for study involves the use of a geostationary satellite with a large multi-beam antenna to provide a major part of the communications and control network between participating utilities and various elements of their power distribution networks, including customer loads. Electric utility communications requirements are projected through 1995 in order to size the required capacity of the system. Two basic systems are examined: a one-way system for load control, and a two-way system for distribution system monitoring and control, including customer meter reading. An operating protocol is proposed for each system. Preliminary cost estimates are identified element by element. Finally, expansion of the basic system to include a set of ancillary communications functions is briefly discussed.

Vaisnys, A.; Bergen, L.

1980-01-01

347

The Earth Radiation Budget Satellite System  

Microsoft Academic Search

The scientific objectives of an Earth Radiation Budget Satellite System (ERBSS) are discussed along with the associated data analysis methods, mission analysis, and the instrument systems. High resolution data on the scale of about 250 km over the entire globe are essential to gain insight into such features as the development of sea-surface temperature anomalies, radiation effects of ice and

C. V. Woerner; J. E. Cooper; E. F. Harrison; G. R. Young

1978-01-01

348

Satellite power systems: Status and planned activities  

Microsoft Academic Search

The general progress in satellite power system (SPS) system definition and assessment activities to date is summarized, and selected technical issues identified as being crucial for the photovoltaic solar energy conversion subsystem of the reference concept are reviewed. The requirements of the photovoltaic subsystem are discussed with respect to the alternative power transmission options studied by NASA since October 1978,

D. Kassing

1980-01-01

349

Applications systems verification and transfer project. Volume 7: Cost/benefit analysis for the ASVT on operational applications of satellite snow-cover observations  

NASA Technical Reports Server (NTRS)

The results of the OASSO ASVT's were used to estimate the benefits accruing from the added information available from satellite snowcover area measurement. Estimates of the improvement in runoff prediction due to addition of SATSCAM were made by the Colorado ASVT personnel. The improvement estimate is 6-10%. Data were applied to subregions covering the Western States snow area amended by information from the ASVT and other watershed experts to exclude areas which are not impacted by snowmelt runoff. Benefit models were developed for irrigation and hydroenergy uses. The benefit/cost ratio is 72:1. Since only two major benefit contributors were used and since the forecast improvement estimate does not take into account future satellite capabilities these estimates are considered to be conservative. The large magnitude of the benefit/cost ratio supports the utility and applicability of SATSCAM.

Castruccio, P.; Loats, H.; Lloyd, D.; Newman, P.

1981-01-01

350

Health Monitoring of a Satellite System  

NASA Technical Reports Server (NTRS)

A health monitoring system based on analytical redundancy is developed for satellites on elliptical orbits. First, the dynamics of the satellite including orbital mechanics and attitude dynamics is modelled as a periodic system. Then, periodic fault detection filters are designed to detect and identify the satellite's actuator and sensor faults. In addition, parity equations are constructed using the algebraic redundant relationship among the actuators and sensors. Furthermore, a residual processor is designed to generate the probability of each of the actuator and sensor faults by using a sequential probability test. Finally, the health monitoring system, consisting of periodic fault detection lters, parity equations and residual processor, is evaluated in the simulation in the presence of disturbances and uncertainty.

Chen, Robert H.; Ng, Hok K.; Speyer, Jason L.; Guntur, Lokeshkumar S.; Carpenter, Russell

2004-01-01

351

An advanced domestic satellite communications system  

NASA Technical Reports Server (NTRS)

An updated traffic projection for U.S. domestic satellite communications service covering a period of 15 years; mid-1980 to mid-1995 was prepared. This model takes into account expected technology advances and reductions in transmission costs, legislative and regulatory changes permitting increased competition, and rising energy costs which will encourage more extensive substitution of telecommunications for travel. The historical development and current status of satellite systems are discussed as well as the characteristics of follow-on systems. Orbital arc utilization, spacecraft configuration for single shuttle launch, Earth station configuration, and system costs are examined. Areas which require technology development include multiple beam frequency reuse antennas, on-board switching, intersatellite links, and ka-band operation. Packing and deployment schemes for enclosing the satellite within the shuttle orbiter bay must also be devised.

1980-01-01

352

Verifying command sequences for satellite systems  

NASA Astrophysics Data System (ADS)

We present a formal basis for the design of a Checker used in validating safe schedules and in selecting error recovery schedules for satellite control systems. This design includes a high-level specification of Checker behavior and properties (called flight rules) of safe schedules. Specifications are written in Timed Linear Logic (TLL). Validation of schedules is performed in terms of real-time telemetry and deduction system proof rules. Telemetry (state information for satellite subsystems) serves as input to the Checker. Detection of violation of a flight rule by the Checker results in the selection of a contingency plan (error recovery schedule). The Checker is illustrated in terms of the TOPEX/Poseidon Oceanographic Satellite System.

Peters, James F., III; Ramanna, Sheela

1992-10-01

353

Satellite Power System (SPS) public outreach experiment  

NASA Technical Reports Server (NTRS)

An outreach experiment was conducted to improve the results of the satellite power system (SPS) concept development and evaluation program. The objectives of the outreach were to: (1) determine the areas of major concern relative to the SPS concept and (2) gain experience with an outreach process for use in future public involvement. The response to the outreach effort was positive, suggesting that the effort extended by the SPS project division to encourage an information exchange with the public was well received. The responses were analyzed and from them some questions and answers about the satellite power system are presented.

Mcneal, S. R.

1980-01-01

354

Low-power magnetometer observation with satellite data transmission at unmanned site in Antarctica  

NASA Astrophysics Data System (ADS)

We will report technical experiences from 6 years of unmanned low power magnetometer observation in Antarctica with daily data transmission via Iridium satellite telephone link. One of the difficulties of unmanned observation in Antarctica is dark winter months in which power supply from solar panel can not be expected. One solution for this difficulty is to minimize the power consumption (as small as ~1 W) to manage the observation in winter months with limited amount of batteries (~400Ah). Another difficulty is to collect data from the observation site. It is quite expensive and laborious to send a party to the observation site to obtain the data in Antarctica. Although cost for satellite communication is expensive, it is much more economical to collect data via satellite data link by installing a telephone terminal into the observation system. It seems that power consumption of a satellite phone (~10 W) does not fit to the low power system. However, as long as the observed data is not too large (<1 Mbyte per day), turn on period of the satellite phone is short (<1 hour per day) and the daily average of total power consumption lies within the available power of ~1 W. We have developed low-power magnetometer system with Iridium satellite phone data link. Basic design of the low-power system is similar to that developed by British Antarctic Survey (intermittent operation of magnetometer and GPS). However, we have made some improvements; reduced power consumption (0.2 W) at high sampling rate (1Hz) and increased sensitivity (0.2nT), so that geomagnetic pulsation study can be possible. In our observation system, satellite data transfer is only made in sunlit season with the total power consumption of 1 W (0.8W for Iridium phone and 0.2W for others). During dark winter months, observed data are stored in CF memory with diminished power consumption of 0.2W. When the sun comes in spring, the stored data are transmitted along with the daily observed data. It takes nearly two months to complete the transmission of data stored in winter months. We have installed two sets of low-power magnetometer at inland and coastal area in January, 2007. We added one set every austral summer and, by January 2010, 5 magnetometers are deployed within a radius of 700km from Syowa Station. The observed data can be used for the study of magnetic pulsations, as well as small and medium scale structure of ionospheric currents at the time of auroral substorm.

Yamagishi, H.; Kadokura, A.

2012-12-01

355

Fast Emission Estimates in China Constrained by Satellite Observations (Invited)  

NASA Astrophysics Data System (ADS)

Emission inventories of air pollutants are crucial information for policy makers and form important input data for air quality models. Unfortunately, bottom-up emission inventories, compiled from large quantities of statistical data, are easily outdated for an emerging economy such as China, where rapid economic growth changes emissions accordingly. Alternatively, top-down emission estimates from satellite observations of air constituents have important advantages of being spatial consistent, having high temporal resolution, and enabling emission updates shortly after the satellite data become available. Constraining emissions from concentration measurements is, however, computationally challenging. Within the GlobEmission project of the European Space Agency (ESA) a new algorithm has been developed, specifically designed for fast daily emission estimates of short-lived atmospheric species on a mesoscopic scale (0.25 × 0.25 degree) from satellite observations of column concentrations. The algorithm needs only one forward model run from a chemical transport model to calculate the sensitivity of concentration to emission, using trajectory analysis to account for transport away from the source. By using a Kalman filter in the inverse step, optimal use of the a priori knowledge and the newly observed data is made. We apply the algorithm for NOx emission estimates in East China, using the CHIMERE model together with tropospheric NO2 column retrievals of the OMI and GOME-2 satellite instruments. The observations are used to construct a monthly emission time series, which reveal important emission trends such as the emission reduction measures during the Beijing Olympic Games, and the impact and recovery from the global economic crisis. The algorithm is also able to detect emerging sources (e.g. new power plants) and improve emission information for areas where proxy data are not or badly known (e.g. shipping emissions). The new emission estimates result in a better agreement between observations and simulations of air pollutant concentrations, facilitating improved air quality forecasts. The EU project MarcoPolo will combine these emission estimates from space with statistical information on e.g. land use, population density and traffic to construct a new up-to-date emission inventory for China.

Mijling, B.; van der A, R.

2013-12-01

356

Comparing soil moisture memory in satellite observations and models  

NASA Astrophysics Data System (ADS)

A major obstacle to a correct parametrization of soil processes in large scale global land surface models is the lack of long term soil moisture observations for large parts of the globe. Currently, a compilation of soil moisture data derived from a range of satellites is released by the ESA Climate Change Initiative (ECV_SM). Comprising the period from 1978 until 2010, it provides the opportunity to compute climatological relevant statistics on a quasi-global scale and to compare these to the output of climate models. Our study is focused on the investigation of soil moisture memory in satellite observations and models. As a proxy for memory we compute the autocorrelation length (ACL) of the available satellite data and the uppermost soil layer of the models. Additional to the ECV_SM data, AMSR-E soil moisture is used as observational estimate. Simulated soil moisture fields are taken from ERA-Interim reanalysis and generated with the land surface model JSBACH, which was driven with quasi-observational meteorological forcing data. The satellite data show ACLs between one week and one month for the greater part of the land surface while the models simulate a longer memory of up to two months. Some pattern are similar in models and observations, e.g. a longer memory in the Sahel Zone and the Arabian Peninsula, but the models are not able to reproduce regions with a very short ACL of just a few days. If the long term seasonality is subtracted from the data the memory is strongly shortened, indicating the importance of seasonal variations for the memory in most regions. Furthermore, we analyze the change of soil moisture memory in the different soil layers of the models to investigate to which extent the surface soil moisture includes information about the whole soil column. A first analysis reveals that the ACL is increasing for deeper layers. However, its increase is stronger in the soil moisture anomaly than in its absolute values and the first even exceeds the latter in the deepest layer. From this we conclude that the seasonal soil moisture variations dominate the memory close to the surface but these are dampened in lower layers where the memory is mainly affected by longer term variations.

Stacke, Tobias; Hagemann, Stefan; Loew, Alexander

2013-04-01

357

ORBITAL DEPENDENCE OF GALAXY PROPERTIES IN SATELLITE SYSTEMS OF GALAXIES  

SciTech Connect

We study the dependence of satellite galaxy properties on the distance to the host galaxy and the orbital motion (prograde and retrograde orbits) using the Sloan Digital Sky Survey (SDSS) data. From SDSS Data Release 7, we find 3515 isolated satellite systems of galaxies at z < 0.03 that contain 8904 satellite galaxies. Using this sample, we construct a catalog of 635 satellites associated with 215 host galaxies whose spin directions are determined by our inspection of the SDSS color images and/or by spectroscopic observations in the literature. We divide satellite galaxies into prograde and retrograde orbit subsamples depending on their orbital motion with respect to the spin direction of the host. We find that the number of galaxies in prograde orbit is nearly equal to that of retrograde orbit galaxies: the fraction of satellites in prograde orbit is 50% {+-} 2%. The velocity distribution of satellites with respect to their hosts is found to be almost symmetric: the median bulk rotation of satellites is -1 {+-} 8 km s{sup -1}. It is found that the radial distribution of early-type satellites in prograde orbit is strongly concentrated toward the host while that of retrograde ones shows much less concentration. We also find the orbital speed of late-type satellites in prograde orbit increases as the projected distance to the host (R) decreases while the speed decreases for those in retrograde orbit. At R less than 0.1 times the host virial radius (R < 0.1r{sub vir,host}), the orbital speed decreases in both prograde and retrograde orbit cases. Prograde satellites are on average fainter than retrograde satellites for both early and late morphological types. The u - r color becomes redder as R decreases for both prograde and retrograde orbit late-type satellites. The differences between prograde and retrograde orbit satellite galaxies may be attributed to their different origin or the different strength of physical processes that they have experienced through hydrodynamic interactions with their host galaxies.

Hwang, Ho Seong; Park, Changbom, E-mail: hoseong.hwang@cea.f, E-mail: cbp@kias.re.k [School of Physics, Korea Institute for Advanced Study, Seoul 130-722 (Korea, Republic of)

2010-09-01

358

Satellite reconnaissance  

NASA Astrophysics Data System (ADS)

The potential of the observation equipment in remote sensing satellites is described. United States meteorology, land use and oceanography satellites and the major US Earth observation programs are listed. Imaging satellite systems are described such as: visible light and near infrared, thermal IR window, and microwave window. It is concluded that a geometrical resolution between 10 and 40 m can be expected. In order to reduce the data flow from the satellite system the input side of the system (the object-sensor interaction) has to be known. Satellites with synthetic aperture radar are increasingly important, but satellites can never fully replace observations with aircraft and drones.

Deloor, G. P.

1984-06-01

359

The investigation of tethered satellite system dynamics  

NASA Technical Reports Server (NTRS)

Progress in tethered satellite system dynamics research is reported. A retrieval rate control law with no angular feedback to investigate the system's dynamic response was studied. The initial conditions for the computer code which simulates the satellite's rotational dynamics were extended to a generic orbit. The model of the satellite thrusters was modified to simulate a pulsed thrust, by making the SKYHOOK integrator suitable for dealing with delta functions without loosing computational efficiency. Tether breaks were simulated with the high resolution computer code SLACK3. Shuttle's maneuvers were tested. The electric potential around a severed conductive tether with insulator, in the case of a tether breakage at 20 km from the Shuttle, was computed. The electrodynamic hazards due to the breakage of the TSS electrodynamic tether in a plasma are evaluated.

Lorenzini, E.

1985-01-01

360

Satellite sound broadcasting system study: Mobile considerations  

NASA Technical Reports Server (NTRS)

Discussed here is the mobile reception part of a study to investigate a satellite sound broadcast system in the UHF or L bands. Existing propagation and reception measurements are used with proper interpretation to evaluate the signaling, coding, and diversity alternatives suitable for the system. Signal attenuation in streets shadowed by buildings appear to be around 29 db, considerably higher than the 10 db adopted by CCIR. With the marriage of proper technologies, an LMSS class satellite can provide substantial direct satellite audio broadcast capability in UHF or L bands for high quality mobile and portable indoor reception by low cost radio receivers. This scheme requires terrestrial repeaters for satisfactory mobile reception in urban areas. A specialized bandwidth efficient spread spectrum signalling technique is particularly suitable for the terrestrial repeaters.

Golshan, Nasser

1990-01-01

361

Second generation business satellite systems for Europe  

NASA Astrophysics Data System (ADS)

Attention is given to the characteristics of the market and its growth trends, and possible second-generation business satellite systems for use in Western Europe starting in about 1990 are described. It is noted that the total satellite traffic may be very large, reaching 530 Mbit/s by 1996, and could be several times greater should a strong video market develop. A single TDMA system is proposed that is designed to meet customer needs. Spectral saturation is obviated by employing multiple spot beams working in both the available European exclusive frequency bands: 12/14 and 20/30 GHz. On-board switching between all the transponders at a common intermediate frequency or at baseband guarantees full user interconnectivity irrespective of earth-station location or operating frequency. Dual-band working also permits extremely economic use of satellite capacity even in the event of an uneven or unpredictable geographical distribution of customers.

Serpell, S. C.

362

PHEMU 2003 campaign: observations of the mutual phenomena of the Galilean satellites in Romania  

NASA Astrophysics Data System (ADS)

We present CCD, photoelectric, and video observations of selected mutual phenomena of the Galilean satellites. The campaign was carried out in Bucharest and Cluj-Napoca as part of the PHEMU2003 international effort. Five different optical systems were used for data acquisition. Here we report the observational results obtained in acceptable meteorological conditions for twenty mutual phenomena, nine eclipses, and eleven occultations. A preliminary analysis of the observations estimates the accuracy of the data.

Arlot, J.-E.; Chis, G.-D.; Farkas, L.; Moldovan, D.; Nedelcu, A.; Popescu, P.; Sorescu, S.; Stavinschi, M.; Serbanescu, L.; Tudose, V.; Turcu, V.

2005-08-01

363

Gas Flaring Volume Estimates with Multiple Satellite Observations  

NASA Astrophysics Data System (ADS)

Flammable gases (primarily methane) are a common bi-product associated with oil wells. Where there is no infrastructure to use the gas or bring it to market, the gases are typically flared off. This practice is more common at remote sites, such as an offshore drilling platform. The Defense Meteorological Satellite Program (DMSP) is a series of satellites with a low-light imager called the Operational Linescan System (OLS). The OLS, which detects the flares at night, has been a valuable tool in the estimation of flared gas volume [Elvidge et al, 2009]. The use of the Moderate Resolution Imaging Spectroradiometer (MODIS) fire product has been processed to create products suitable for an independent estimate of gas flaring on land. We are presenting the MODIS flare product, the results of our MODIS gas flare volume analysis, and independent validation of the published DMSP estimates. Elvidge, C. D., Ziskin, D., Baugh, K. E., Tuttle, B. T., Ghosh, T., Pack, D. W., Erwin, E. H., Zhizhin, M., 2009, "A Fifteen Year Record of Global Natural Gas Flaring Derived from Satellite Data", Energies, 2 (3), 595-622

Ziskin, D. C.; Elvidge, C.; Baugh, K.; Ghosh, T.; Hsu, F. C.

2010-12-01

364

Satellite observations of desert dust-induced Himalayan snow darkening  

NASA Astrophysics Data System (ADS)

The optically thick aerosol layer along the southern edge of the Himalaya has been subject of several recent investigations relating to its radiative impacts on the South Asian summer monsoon and regional climate forcing. Prior to the onset of summer monsoon, mineral dust from southwest Asian deserts is transported over the Himalayan foothills on an annual basis. Episodic dust plumes are also advected over the Himalaya, visible as dust-laden snow surface in satellite imagery, particularly in western Himalaya. We examined spectral surface reflectance retrieved from spaceborne MODIS observations that show characteristic reduction in the visible wavelengths (0.47 µm) over western Himalaya, associated with dust-induced solar absorption. Case studies as well as seasonal variations of reflectance indicate a significant gradient across the visible (0.47 µm) to near-infrared (0.86 µm) spectrum (VIS-NIR), during premonsoon period. Enhanced absorption at shorter visible wavelengths and the resulting VIS-NIR gradient is consistent with model calculations of snow reflectance with dust impurity. While the role of black carbon in snow cannot be ruled out, our satellite-based analysis suggests the observed spectral reflectance gradient dominated by dust-induced solar absorption during premonsoon season. From an observational viewpoint, this study underscores the importance of mineral dust deposition toward darkening of the western Himalayan snow cover, with potential implications to accelerated seasonal snowmelt and regional snow albedo feedbacks.

Gautam, Ritesh; Hsu, N. Christina; Lau, William K.-M.; Yasunari, Teppei J.

2013-03-01

365

Observational detection of eight mutual eclipses and occultations between the satellites of Uranus  

NASA Astrophysics Data System (ADS)

Aims: We carried out observations, with five different instruments ranging in aperture from 0.4 m to 10 m, of the satellites of Uranus during that planet's 2007 Equinox. Our observations covered specific intervals of time when mutual eclipses and occultations were predicted. Methods: The observations were carried out in the near-infrared part of the spectrum to mitigate the glare from the planet. Frames were acquired at rates >1/min. Following modelling and subtraction of the planetary source from these frames, differential aperture photometry was carried out on the satellite pairs involved in the predicted events. In all cases but one, nearby bright satellites were used as reference sources. Results: We have obtained fifteen individual lightcurves, eight of which show a clear drop in the flux from the satellite pair, indicating that a mutual event took place. Three of these involve the faint satellite Miranda. All eight lightcurves were model-fitted to yield best estimates of the time of maximum flux drop and the impact parameter. In three cases best-fit albedo ratios were also derived. We used these estimates to generate intersatellite astrometric positions with typical formal uncertainties of <0.01 arcsec, several times better than conventional astrometry of these satellites. The statistics of our estimated event midtimes show a systematic lag, with the observations later than predictions. In addition, lightcurves of two partial eclipses of Miranda show no statistically significant evidence of a light drop, at variance with the predictions. These indicate that new information about the Uranian satellite system is contained in observations of mutual events acquired here and by other groups.

Christou, A. A.; Lewis, F.; Roche, P.; Hashimoto, Y.; O'Donoghue, D.; Worters, H.; Buckley, D. A. H.; Michalowski, T.; Asher, D. J.; Bitsaki, A.; Psalidas, A.; Tsamis, V.; Gourgouliatos, K. N.; Liakos, A.; Hidas, M. G.; Brown, T. M.

2009-04-01

366

Observations of dust spikes on the Wind satellite  

NASA Astrophysics Data System (ADS)

Stimulated by the work on impulsive waveforms (spikes) on the STEREO satellites, we have investigated similar waveforms observed by the Wind/Waves Time Domain Sampler (TDS) on Wind. As Wind is spinning, and has antennas of different lengths with a significant separation, additional understanding of the impact and emission process can be expected. The surface, glass coated with Indium Tin Oxide, is different from that of the STEREOs, germanium coated mylar, which should also affect the processes. Only a small percentage of the spikes are due to interference of an expected kind. The rest are consistent with impacts of dust. Viewed in detail, the spikes attributed to dust impacts have a wide variety of waveforms, and a wide variety of parameters even for waveforms selected as similar. Observations and summaries will be presented. Progress toward a calibration of the observations, in terms of dust mass and energy, will be summarized.

Kellogg, Paul J.; Goetz, Keith; Monson, Steven

2013-04-01

367

Crustal movement from satellite observations in the Australian region  

NASA Astrophysics Data System (ADS)

The paper outlines the crustal structure in the Australian and Papua New Guinea regions, and explains the need for data on crustal motion and deformation. Two other papers at the same meeting describe operations to investigate crustal strain on the Australian continent (Stolz and Masters, 1982; Wellman, 1981). This paper describes a third project, designed to determine the motion of plates in the Papua New Guinea region. Here the structure and motions are complex, with several minor plates between the major Indo-Australian and Pacific plates. Fifteen observing stations were selected so that there were at least two on each plate, and in April-May 1981 observations were taken to fix their position using five Doppler satellite receivers in a multi-station configuration. The observations are currently being processed and analysed. It is hoped to repeat the measurements at regular intervals.

Angus-Leppan, Peter V.; Allman, John S.; Sloane, Barry

1983-09-01

368

Satellite observations of an annual cycle in the Agulhas Current  

NASA Astrophysics Data System (ADS)

Ocean models show an annual cycle in the Agulhas Current transport which has not yet been confirmed in analyses of in-situ or satellite observations. A cross-stream coordinate approach is used to study the variability of the Agulhas Current from 18 years of along-track altimetry and merged altimetry and close to 7 years of high frequency Sea Surface Temperature (SST) observations. While the position and width of the Agulhas Current's dynamical core do not display an annual cycle, the geostrophic current speed at the current's core exhibits distinct seasonal variations, with a stronger flow observed in austral summer. The annual cycle dominates the frequency spectra of the current's core geostrophic velocities.

Krug, M.; Tournadre, J.

2012-08-01

369

Reconstructing the orbit of the Chelyabinsk meteor using satellite observations  

NASA Astrophysics Data System (ADS)

The large number of objects in a range of orbits around the Sun means that some will inevitably intersect the Earth, becoming a meteor. These objects are commonly comet fragments or asteroids. To determine the type of a particular meteor requires knowledge of its trajectory and orbital path that is typically estimated by using ground-based observations such as images or radar measurements. A lack of data can, however, make this difficult and create large uncertainties in the reconstructed orbit. Here I show a new method for estimating a meteor's trajectory, and hence allowing computation of the orbit, based upon measurements from satellite sensors. The meteor that fell on 15 February 2013 is used as an example and the resulting orbit is in broad agreement with estimates from other observations. This new technique represents an alternative method for trajectory determination that may be particularly useful in areas where ground-based observations are sparse.

Proud, S. R.

2013-07-01

370

High resolution earth observation satellites and services in the next decade a European perspective  

NASA Astrophysics Data System (ADS)

Projects to use very high resolution optical satellite sensor data started in the late 90s and are believed to be the major driver for the commercialisation of earth observation. The global political security situation and updated legislative frameworks created new opportunities for high resolution, dual use satellite systems. In addition to new optical sensors, very high resolution synthetic aperture radars will become in the next few years an important component in the imaging satellite fleet. The paper will review the development in this domain so far, and give perspectives on future emerging markets and opportunities. With dual-use satellite initiatives and new political frameworks agreed between the European Commission and the European Space Agency (ESA), the European market becomes very attractive for both service suppliers and customers. The political focus on "Global Monitoring for Environment and Security" (GMES) and the "European Defence and Security Policy" drive and amplify this demand which ranges from low resolution climate monitoring to very high resolution reconnaissance tasks. In order to create an operational and sustainable GMES in Europe by 2007, the European infrastructure need to be adapted and extended. This includes the ESA SENTINEL and OXYGEN programmes, aiming for a fleet of earth observation satellites and an open and operational earth observation ground segment. The harmonisation of national and regional geographic information is driven by the European Commission's INSPIRE programme. The necessary satellite capacity to complement existing systems in the delivery of space based data required for GMES is currently under definition. Embedded in a market with global competition and in the global political framework of a Global Earth Observation System of Systems, European companies, agencies and research institutions are now contributing to this joint undertaking. The paper addresses the chances, risks and options for the future.

Schreier, Gunter; Dech, Stefan

2005-07-01

371

Modeling Prairie Pothole Lakes: Linking Satellite Observation and Calibration (Invited)  

NASA Astrophysics Data System (ADS)

This paper examines the response of a complex lake wetland system to variations in climate. The focus is on the lakes and wetlands of the Missouri Coteau, which is part of the larger Prairie Pothole Region of the Central Plains of North America. Information on lake size was enumerated from satellite images, and yielded power law relationships for different hydrological conditions. More traditional lake-stage data were made available to us from the USGS Cottonwood Lake Study Site in North Dakota. A Probabilistic Hydrologic Model (PHM) was developed to simulate lake complexes comprised of tens-of-thousands or more individual closed-basin lakes and wetlands. What is new about this model is a calibration scheme that utilizes remotely-sensed data on lake area as well as stage data for individual lakes. Some ¼ million individual data points are used within a Genetic Algorithm to calibrate the model by comparing the simulated results with observed lake area-frequency power law relationships derived from Landsat images and water depths from seven individual lakes and wetlands. The simulated lake behaviors show good agreement with the observations under average, dry, and wet climatic conditions. The calibrated model is used to examine the impact of climate variability on a large lake complex in ND, in particular, the “Dust Bowl Drought” 1930s. This most famous drought of the 20th Century devastated the agricultural economy of the Great Plains with health and social impacts lingering for years afterwards. Interestingly, the drought of 1930s is unremarkable in relation to others of greater intensity and frequency before AD 1200 in the Great Plains. Major droughts and deluges have the ability to create marked variability of the power law function (e.g. up to one and a half orders of magnitude variability from the extreme Dust Bowl Drought to the extreme 1993-2001 deluge). This new probabilistic modeling approach provides a novel tool to examine the response of the behavior of a complex of closed lakes vary in scale from the footprint of a small house to that of a small city.

Schwartz, F. W.; Liu, G.; Zhang, B.; Yu, Z.

2009-12-01

372

The guiding system with a SIT-TV camera in satellite laser ranging system  

Microsoft Academic Search

The performance of the SIT-TV camera used in the satellite laser ranging (SLR) system at Shanghai, Guangzhou and Changchun stations is introduced in the paper. The feature of the optical parts and the observation effect for faint satellites, such as Lageos and Etalon, are also given.

Wanzhen Chen; Fumin Yang; Chikun Xiao

1994-01-01

373

System specification for the reusable reentry satellite  

NASA Technical Reports Server (NTRS)

The RRS design shall provide a relatively inexpensive method of access to micro and fractional gravity space environments for an extended period of time, with eventual intact recovery on the surface of the Earth. This specification establishes the performance, design, development, and test requirements for the Reusable Reentry Satellite (RRS) system.

1991-01-01

374

Global Navigation Satellite System Software Defined Radio.  

National Technical Information Service (NTIS)

There are two major trends that are driving the nature of GNSS receiver development today. First, there is a growing number of Global Navigation Satellite Systems (GNSS) that exist or are under development, so that in the near future, users will potential...

J. McGinthy

2010-01-01

375

Agent computing applications in distributed satellite systems  

Microsoft Academic Search

Space and satellite systems are considered to be the most extreme environment to design for and are fraught with engineering difficulty. Performance metrics such as fault tolerance, reliability, pre-determinism and heritage are still high of the list of requirements for all missions. But with the advent of modern day electronics, greater computing capability and networking technologies have enabled research into

Christopher P. Bridges; Tanya Vladimirova

2009-01-01

376

Solar power satellite system sizing tradeoffs  

NASA Technical Reports Server (NTRS)

Technical and economic tradeoffs of smaller solar power satellite systems configured with larger antennas, reduced output power, and smaller rectennas, are considered. The differential costs in electricity for seven antenna/rectenna configurations operating at 2.45 GHz and five satellite systems operating at 5.8 GHz are calculated. Two 2.45 GHz configurations dependent upon the ionospheric power density limit are chosen as examples. If the ionospheric limit could be increased to 54 mW sq/cm from the present 23 mW sq/cm level, a 1.53 km antenna satellite operating at 2.45 GHz would provide 5.05 GW of output power from a 6.8 km diameter rectenna. This system gives a 54 percent reduction in rectenna area relative to the reference solar power satellite system at a modest 17 percent increase in electricity costs. At 5.8 GHz, an 0.75 km antenna providing 2.72 GW of power from a 5.8 km diameter rectenna is selected for analysis. This configuration would have a 67 percent reduction in rectenna area at a 36 percent increase in electricity costs. Ionospheric, atmospheric, and thermal limitations are discussed. Antenna patterns for three configurations to show the relative main beam and sidelobe characteristics are included.

Arndt, G. D.; Monford, L. G.

1981-01-01

377

Satellite Power System (SPS) Public Outreach Experiment.  

National Technical Information Service (NTIS)

An outreach experiment was conducted to improve the results of the satellite power system (SPS) concept development and evaluation program. The objectives of the outreach were to: (1) determine the areas of major concern relative to the SPS concept and (2...

S. R. Mcneal

1980-01-01

378

Satellite Power System (SPS) public outreach experiment  

Microsoft Academic Search

An outreach experiment was conducted to improve the results of the satellite power system (SPS) concept development and evaluation program. The objectives of the outreach were to: (1) determine the areas of major concern relative to the SPS concept and (2) gain experience with an outreach process for use in future public involvement. The response to the outreach effort was

S. R. McNeal

1980-01-01

379

Summary assessment of the satellite power system  

Microsoft Academic Search

A three-year intensive assessment of the Satellite Power System (SPS) concept has been concluded. The results indicate that SPS could become a source of baseload electric power in the post-2000 time period. This affirmation must be conditioned by the reported uncertainties in technology, environmental effects, and economic factors which can be overcome only by concentrated research and study in areas

Francis C. Schwenk

1983-01-01

380

Satellite Power System (SPS) student participation  

Microsoft Academic Search

A assessment of methods which are appropriate to initiate student participation in the discussion of a satellite power system (SPS) is presented. Methods which are incorporated into the campus environment and the on-going learning experience are reported. The discussion of individual methods for student participation includes a description of the technique, followed by comments on its enhancing and limiting factors,

A. Ladwig; L. David

1978-01-01

381

Satellite power system (SPS) military implications  

Microsoft Academic Search

This study examines the potential military role, both offensive and defensive, of a Satellite Power System (SPS). The very large orbital power source of the SPS could have a number of potential military applications. Perhaps the most arresting, but certainly one in the very distant future is the possibility of developing an anti-ballistic defense weapon utilizing laser or particle beams.

Ozeroff

1978-01-01

382

Satellite Power System (SPS) military applications  

NASA Technical Reports Server (NTRS)

The potential military role, both offensive and defensive, of a Satellite Power System (SPS) is examined. A number of potential military support possibilities are described. An SPS with military capabilities may have a strong negative impact on international relations if it is not internationalized. The SPS satellite would be vulnerable to military action of an enemy with good space capability, but would experience little or no threat from saboteurs or terrorists, except via the ground controls. The paper concludes with an outline of some of the key issues involved, and a number of recommendations for future study, including some areas for long term efforts.

Ozeroff, M. J.

1978-01-01

383

Speculative histories of the Uranian satellite system  

NASA Astrophysics Data System (ADS)

The hypothetical histories presently considered for the Uranian satellite system are very sensitive to the assumed satellite masses, within the errors of their determinations, as well as to the Uranian tidal effective dissipation function. A determination is made of the resonances that could have been encountered in these histories, and of the orbital eccentricity constraints that would have led to certain capture. It is found that if the mass of Miranda were of the upper extreme value, it would have been locked in a long-term 2/1 orbital resonance with Ariel to form a Laplacelike, three-body resonance that encompassed Umbriel.

Peale, S. J.

1988-05-01

384

The flight of the Tethered Satellite System  

NASA Astrophysics Data System (ADS)

The U.S.-Italian Tethered Satellite System (TSS) Electrodynamics Mission flew aboard ST-46; the 500-kg satellite will be extended from the Shuttle Orbiter, to which it will remain connected via conducting insulated wire tether. TSS-1 constitutes the first effort to resolve the problem postulated in the 1920s by Langmuir, involving the determination of the dynamic current-voltage characteristics of a body that is charged to high potential and located in a magnetized plasma in the absence of physical boundaries. TSS-1 is also a first step to the use of tethers for space power generation and propulsion.

Papadopoulos, Dennis; Drobot, Adam T.; Stone, Nobie

1992-07-01

385

Determination of motion extrema in multi-satellite systems  

NASA Astrophysics Data System (ADS)

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.

Allgeier, Shawn E.

386

Stopwatch Observations of Satellites Made During the Month of May 1973.  

National Technical Information Service (NTIS)

Stopwatch observations made at stations connected with the Section during May 1973 are listed in satellite launch and time order. Two hundred forty one fully reduced observations of 74 satellites are included. (Author)

R. D. Eberst

1973-01-01

387

Correlation of satellite lightning observations with ground-based lightning experiments in Florida, Texas and Oklahoma  

NASA Technical Reports Server (NTRS)

Satellite observations of lightning were correlated with ground-based measurements of lightning from data bases obtained at three separate sites. The percentage of ground-based observations of lightning that would be seen by an orbiting satellite was determined.

Edgar, B. C.; Turman, B. N.

1982-01-01

388

An automated mapping satellite system ( Mapsat).  

USGS Publications Warehouse

The favorable environment of space permits a satellite to orbit the Earth with very high stability as long as no local perturbing forces are involved. Solid-state linear-array sensors have no moving parts and create no perturbing force on the satellite. Digital data from highly stabilized stereo linear arrays are amenable to simplified processing to produce both planimetric imagery and elevation data. A satellite imaging system, called Mapsat, including this concept has been proposed to produce data from which automated mapping in near real time can be accomplished. Image maps as large as 1:50 000 scale with contours as close as a 20-m interval may be produced from Mapsat data. -from Author

Colvocoresses, A. P.

1982-01-01

389

Satellite sound broadcasting system, portable reception  

NASA Technical Reports Server (NTRS)

Studies are underway at JPL in the emerging area of Satellite Sound Broadcast Service (SSBS) for direct reception by low cost portable, semi portable, mobile and fixed radio receivers. This paper addresses the portable reception of digital broadcasting of monophonic audio with source material band limited to 5 KHz (source audio comparable to commercial AM broadcasting). The proposed system provides transmission robustness, uniformity of performance over the coverage area and excellent frequency reuse. Propagation problems associated with indoor portable reception are considered in detail and innovative antenna concepts are suggested to mitigate these problems. It is shown that, with the marriage of proper technologies a single medium power satellite can provide substantial direct satellite audio broadcast capability to CONUS in UHF or L Bands, for high quality portable indoor reception by low cost radio receivers.

Golshan, Nasser; Vaisnys, Arvydas

1990-01-01

390

Geodetic satellite observations in North American (solution NA-9)  

NASA Technical Reports Server (NTRS)

A new detailed geoidal map with claimed accuracies of plus or minus 2 meters (on land), based on gravimetric and satellite data, was presented. With the new geoid and the orthometric heights given, more reliable height constraints were calculated and applied. The basic purpose of this experiment was to compute the new solution NA9 by defining the origin of the system, from the point of view of error propagation, in the most favorable position applying inner constraints and imposing new weighted height constraints to all of the stations. The major differences with respect to formerly published adjustments are presented.

Mueller, I. I.; Reilly, J. P.; Soler, T.

1972-01-01

391

Multipath Study for a Low Altitude Satellite Utilizing a Data Relay Satellite System.  

National Technical Information Service (NTIS)

Technical considerations associated with a low altitude satellite operating in conjuction with a data relay satellite system are reported. Emphasis was placed on the quantitative characterization of mulipath phenomenon and determination of power received ...

D. Eggert

1970-01-01

392

Satellite and Ground Station Configuration for an Iranian National Satellite Communication System.  

National Technical Information Service (NTIS)

A communications satellite system for Iran was designed under contract to National Iranian Radio and Television. Summary results describe the alternatives considered and recommendation configurations for satellites and for major city and rural ground stat...

B. B. Lusignan

1976-01-01

393

Communications satellite system for Africa  

NASA Astrophysics Data System (ADS)

Earlier established requirement estimations were improved upon by contacting African administrations and organizations. An enormous demand is shown to exist for telephony and teletype services in rural areas. It is shown that educational television broadcasting should be realized in the current African transport and communications decade (1978-1987). Radio broadcasting is proposed in order to overcome illiteracy and to improve educational levels. The technical and commercial feasibility of the system is provided by computer simulations which demonstrate how the required objectives can be fulfilled in conjunction with ground networks.

Kriegl, W.; Laufenberg, W.

1980-09-01

394

Satellite-observed characteristics of midwest severe thunderstorm anvils  

NASA Technical Reports Server (NTRS)

The cloud top and anvil structure of severe thunderstorms observed by the GOES satellite are analyzed for five SESAME cases in 1979 and four non-SESAME cases in 1980-1982. The data is compared with previous models and hypotheses, paying particular attention to the V feature and thermal couplets in the IR observations. The characteristics of the cases are examined and related to the upper-level temperature and wind conditions. It is found that the warm points downwind of the cloud top are due to subsidence. The anaylsis suggests the presence of subsidence due to mountainlike waves. A model in which the close-in warm point is produced by both internal cloud air motions and stratospheric flow around and over the cloud top. It is suggested that the distant warm point is due to either a wave perturbation from air flowing over the cloud top, or air flowing horizonatlly around the elevated portion of the cloud top and anvil.

Heymsfield, Gerald M.; Blackmer, Roy H., Jr.

1988-01-01

395

Radar and satellite observations of the storm time cleft  

NASA Astrophysics Data System (ADS)

A combination is made of observations from the Millstone Hill radar (MHR) and the Defense Meteorological Satellite Program's F7 spacecraft of the dayside features on the ionospheric cleft/cusp during the magnetic storm of February 8-9, 1986; the MHR was in the dayside. Attention is given to the two sets of observations for the prenoon sector in order to ascertain the low-altitude signatures of plasma regions in the vicinity of the cusp. Boundary plasma sheet particles coincided with a narrow region of magnetic field-aligned currents, as well as with antisunward convection flows at the equatorward edge of the cleft. Particle and field signatures are identified for the plasma sheet, plasma sheet boundary layer, low latitude boundary layer, cusp, and mantle, at unusually low magnetic latitude during the event.

Yeh, H.-C.; Foster, J. C.; Holt, J. M.; Redus, R. H.; Rich, F. J.

1990-08-01

396

Satellite observations of Whistlers at the Tihany conjugate point  

NASA Astrophysics Data System (ADS)

Collier et al. [2009] have shown a correlation between whistlers observed at Tihany, Hungary, and lightning activity within a few hundred km of Tihany's conjugate point. The lightning data were obtained from the World Wide Lightning Location Network (WWLLN). This network currently only detects approximately 10% of global lightning activity, and also does not measure stroke multiplicity or intensity. However, it is readily apparent that the number of lightning strokes around the conjugate point far exceeds the number of whistlers detected on the ground at Tihany. There are a few possible reasons for this discrepancy. Ionospheric attenuation and the availability of appropriately located ducts may be important. To elucidate this issue, burst mode VLF data from the Demeter satellite were studied in conjunction with whistler data from Tihany and lighting data from around the conjugate point. Fractional hop whistlers identified on Demeter above the conjugate region have been linked to whistlers observed at Tihany.

Delport, Brett; Collier, Andrew; Lichtenberger, Janos; Steinbach, Peter; Parrot, Michel

397

Integration of satellite fire products into MPI Earth System Model  

NASA Astrophysics Data System (ADS)

Fires are the ubiquitous phenomenon affecting all natural biomes. Since the beginning of the satellite Era, fires are being continuously observed from satellites. The most interesting satellite parameter retrieved from satellite measurements is the burned area. Combined with information on biomass available for burning the burned area can be translated into climate relevant carbon emissions from fires into the atmosphere. In this study we integrate observed burned area into a global vegetation model to derive global fire emissions. Global continuous burned area dataset is provided by the Global Fire Emissions Dataset (GFED). GFED products were obtained from MODIS (and pre-MODIS) satellites and are available for the time period of 14 years (1997-2011). This dataset is widely used, well documented and supported by periodical updates containing new features. We integrate the global burned area product into the land model JSBACH, a part of the Earth-System model developed at the Max Plank Institute for Meteorology. The land model JSBACH simulates land biomass in terms of carbon content. Fire is an important disturbance process in the Earth's carbon cycle and affects mainly the carbon stored in vegetation. In the standard JSBACH version fire is represented by process based algorithms. Using the satellite data as an alternative we are targeting better comparability of modeled carbon emissions with independent satellite measurements of atmospheric composition. The structure of burned vegetation inside of a biome can be described as the balance between woody and herbaceous vegetation. GFED provides in addition to the burned area satellite derived information of the tree cover distribution within the burned area. Using this dataset, we can attribute the burned area to the respective simulated herbaceous or woody biomass within the vegetation model. By testing several extreme cases we evaluate the quantitative impact of vegetation balance between woody and herbaceous vegetation on fire carbon emissions. The integration procedure of satellite observed burned area into JSBACH is developed in a way that it can be easily adapted to future satellite fire datasets (e.g. expected ESA CCI Fire-ECV products). Here we will also discuss further possibilities for the integration of satellite fire data into vegetation models.

Khlystova, Iryna G.; Kloster, Silvia

2013-04-01

398

A computer system for geosynchronous satellite navigation  

NASA Technical Reports Server (NTRS)

A computer system specifically designed to estimate and predict Geostationary Operational Environmental Satellite (GOES-4) navigation parameters using Earth imagery is described. The estimates are needed for spacecraft maneuvers while prediction provide the capability for near real-time image registration. System software is composed of four functional subsystems: (1) data base management; (2) image processing; (3) navigation; and (4) output. Hardware consists of a host minicomputer, a cathode ray tube terminal, a graphics/video display unit, and associated input/output peripherals. System validity is established through the processing of actual imagery obtained by sensors on board the Synchronous Meteorological Satellite (SMS-2). Results indicate the system is capable of operationally providing both accurate GOES-4 navigation estimates and images with a potential registration accuracy of several picture elements (pixels).

Koch, D. W.

1980-01-01

399

Antenna drive system for the Nimbus satellite  

NASA Technical Reports Server (NTRS)

A two-axis drive system is described for pointing a high gain antenna. Motion about each axis is provided by identical drive mechanisms. Only three gear passes are required to obtain the necessary 900:1 gear reduction. The drive system is a primary element of an experiment that will provide a real time data link between Nimbus and ground stations. Data are transmitted from Nimbus to the applications technology satellite, which relays the data to ground stations.

Wedlake, G. J.; Loudon, J. D.

1972-01-01

400

Optical design of resource satellite system  

NASA Astrophysics Data System (ADS)

The optical system of an infrared multi-spectrum scanner used on the resource satellite is presented in this paper. The principles of spectrum-dividing and imaging, the designing of optical system, the optimization of the assemblage and the adjusting of relay optical system are discussed. According to the general principles of infrared systems, R-C system is used in designing of the primary optical system. There are two methods to design the relay optical system, one of which consists of a complex prism and the other uses a binary optical element. The results and imaging quality of the two methods generated by ZEMAX are given. In the system using complex prism, each wavelength band consists of an R-C system. The diffractive system uses diffractive-refractive hybrid systems to divide spectrum, image and achromatize. The results show that the image quality of the designed system is good enough to meet the practical requirements.

Cao, Yinhua; Li, Lin; Liu, Jiaguo; Liu, Yufeng; Huang, Yifan

2005-02-01

401

Cooling systems for satellite remote sensing instrumentation  

NASA Technical Reports Server (NTRS)

The characteristics of a cryogenic cooling system for the Pollution Monitoring Satellite (PMS) are discussed. Studies were conducted to make the following determinations: (1) the characteristics and use of proven and state-of-the-art cryogenic cooling systems for six specified ranges of performance, (2) the system most applicable for each of the six cooling categories, and (3) conceptual designs for candidate system for each of the six representative cooling categories. The six cooling categories of electrical loads are defined. The desired mission life for the cooling system is two years with both continuous and intermittent operating conditions.

Copeland, R. J.; Oren, J. A.

1974-01-01

402

Networks for Autonomous Formation Flying Satellite Systems  

NASA Technical Reports Server (NTRS)

The performance of three communications networks to support autonomous multi-spacecraft formation flying systems is presented. All systems are comprised of a ten-satellite formation arranged in a star topology, with one of the satellites designated as the central or "mother ship." All data is routed through the mother ship to the terrestrial network. The first system uses a TCP/lP over ATM protocol architecture within the formation the second system uses the IEEE 802.11 protocol architecture within the formation and the last system uses both of the previous architectures with a constellation of geosynchronous satellites serving as an intermediate point-of-contact between the formation and the terrestrial network. The simulations consist of file transfers using either the File Transfer Protocol (FTP) or the Simple Automatic File Exchange (SAFE) Protocol. The results compare the IF queuing delay, and IP processing delay at the mother ship as well as application-level round-trip time for both systems, In all cases, using IEEE 802.11 within the formation yields less delay. Also, the throughput exhibited by SAFE is better than FTP.

Knoblock, Eric J.; Konangi, Vijay K.; Wallett, Thomas M.; Bhasin, Kul B.

2001-01-01

403

Antartic sea ice, 1973 - 1976: Satellite passive-microwave observations  

NASA Technical Reports Server (NTRS)

Data from the Electrically Scanning Microwave Radiometer (ESMR) on the Nimbus 5 satellite are used to determine the extent and distribution of Antarctic sea ice. The characteristics of the southern ocean, the mathematical formulas used to obtain quantitative sea ice concentrations, the general characteristics of the seasonal sea ice growth/decay cycle and regional differences, and the observed seasonal growth/decay cycle for individual years and interannual variations of the ice cover are discussed. The sea ice data from the ESMR are presented in the form of color-coded maps of the Antarctic and the southern oceans. The maps show brightness temperatures and concentrations of pack ice averaged for each month, 4-year monthly averages, and month-to-month changes. Graphs summarizing the results, such as areas of sea ice as a function of time in the various sectors of the southern ocean are included. The images demonstrate that satellite microwave data provide unique information on large-scale sea ice conditions for determining climatic conditions in polar regions and possible global climatic changes.

Zwally, H. J.; Comiso, J. C.; Parkinson, C. L.; Campbell, W. J.; Carsey, F. D.; Gloersen, P.

1983-01-01

404

Arctic Sea ice studies with passive microwave satellite observations  

NASA Technical Reports Server (NTRS)

The objectives of this research are: (1) to improve sea ice concentration determinations from passive microwave space observations; (2) to study the role of Arctic polynyas in the production of sea ice and the associated salinization of Arctic shelf water; and (3) to study large scale sea ice variability in the polar oceans. The strategy is to analyze existing data sets and data acquired from both the DMSP SSM/I and recently completed aircraft underflights. Special attention will be given the high resolution 85.5 GHz SSM/I channels for application to thin ice algorithms and processes studies. Analysis of aircraft and satellite data sets is expected to provide a basis for determining the potential of the SSM/I high frequency channels for improving sea ice algorithms and for investigating oceanic processes. Improved sea ice algorithms will aid the study of Arctic coastal polynyas which in turn will provide a better understanding of the role of these polynyas in maintaining the Arctic watermass structure. Analysis of satellite and archived meteorological data sets will provide improved estimates of annual, seasonal and shorter-term sea ice variability.

Cavalieri, D. J.

1988-01-01

405

An Examination of Intertidal Temperatures Through Remotely Sensed Satellite Observations  

NASA Astrophysics Data System (ADS)

MODIS Aqua and Terra satellites produce both land surface temperatures and sea surface temperatures using calibrated algorithms. In this study, the land surface temperatures were retrieved during clear-sky (non-cloudy) conditions at a 1 km2 resolution (overpass time at 10:30 am) whereas the sea surface temperatures are also retrieved during clear-sky conditions at approximately 4 km resolution (overpass time at 1:30 pm). The purpose of this research was to examine remotely sensed sea surface (SST), intertidal (IST), and land surface temperatures (LST), in conjunction with observed in situ mussel body temperatures, as well as associated weather and tidal data. In Strawberry Hill, Oregon, it was determined that intertidal surface temperatures are similar to but distinctly different from land surface temperatures although influenced by sea surface temperatures. The air temperature and differential heating throughout the day, as well as location in relation to the shore, can greatly influence the remotely sensed surface temperatures. Therefore, remotely sensed satellite data is a very useful tool in examining intertidal temperatures for regional climatic changes over long time periods and may eventually help researchers forecast expected climate changes and help determine associated biological implications.

Lakshmi, V.