Geomorphometric multi-scale analysis for the recognition of Moon surface features using multi-resolution DTMs

NASA Astrophysics Data System (ADS)

Li, Ke; Chen, Jianping; Sofia, Giulia; Tarolli, Paolo

2014-05-01

Moon surface features have great significance in understanding and reconstructing the lunar geological evolution. Linear structures like rilles and ridges are closely related to the internal forced tectonic movement. The craters widely distributed on the moon are also the key research targets for external forced geological evolution. The extremely rare availability of samples and the difficulty for field works make remote sensing the most important approach for planetary studies. New and advanced lunar probes launched by China, U.S., Japan and India provide nowadays a lot of high-quality data, especially in the form of high-resolution Digital Terrain Models (DTMs), bringing new opportunities and challenges for feature extraction on the moon. The aim of this study is to recognize and extract lunar features using geomorphometric analysis based on multi-scale parameters and multi-resolution DTMs. The considered digital datasets include CE1-LAM (Chang'E One, Laser AltiMeter) data with resolution of 500m/pix, LRO-WAC (Lunar Reconnaissance Orbiter, Wide Angle Camera) data with resolution of 100m/pix, LRO-LOLA (Lunar Reconnaissance Orbiter, Lunar Orbiter Laser Altimeter) data with resolution of 60m/pix, and LRO-NAC (Lunar Reconnaissance Orbiter, Narrow Angle Camera) data with resolution of 2-5m/pix. We considered surface derivatives to recognize the linear structures including Rilles and Ridges. Different window scales and thresholds for are considered for feature extraction. We also calculated the roughness index to identify the erosion/deposits area within craters. The results underline the suitability of the adopted methods for feature recognition on the moon surface. The roughness index is found to be a useful tool to distinguish new craters, with higher roughness, from the old craters, which present a smooth and less rough surface.

Mapping Sequence performed during the STS-117 R-Bar Pitch Maneuver

NASA Image and Video Library

2007-06-10

ISS015-E-11320 (10 June 2007) --- This is one of a series of images, photographed with a digital still camera using an 800mm focal length, featuring the different areas of the Space Shuttle Atlantis as it approached the International Space Station and performed a back-flip to accommodate close scrutiny by eyeballs and cameras. This image shows part of Atlantis' cabin and its docking system, which a short time later was involved in linking up with the orbital outpost. Distance from the station and shuttle at this time was approximately 600 feet.

Fermilab Recycler Ring BPM Upgrade Based on Digital Receiver Technology

NASA Astrophysics Data System (ADS)

Webber, R.; Crisp, J.; Prieto, P.; Voy, D.; Briegel, C.; McClure, C.; West, R.; Pordes, S.; Mengel, M.

2004-11-01

Electronics for the 237 BPMs in the Fermilab Recycler Ring have been upgraded from a log-amplifier based system to a commercially produced digitizer-digital down converter based system. The hardware consists of a pre-amplifier connected to a split-plate BPM, an analog differential receiver-filter module and an 8-channel 80-MHz digital down converter VME board. The system produces position and intensity with a dynamic range of 30 dB and a resolution of ±10 microns. The position measurements are made on 2.5-MHz bunched beam and barrier buckets of the un-bunched beam. The digital receiver system operates in one of six different signal processing modes that include 2.5-MHz average, 2.5-MHz bunch-by-bunch, 2.5-MHz narrow band, unbunched average, un-bunched head/tail and 89-kHz narrow band. Receiver data is acquired on any of up to sixteen clock events related to Recycler beam transfers and other machine activities. Data from the digital receiver board are transferred to the front-end CPU for position and intensity computation on an on-demand basis through the VME bus. Data buffers are maintained for each of the acquisition events and support flash, closed orbit and turn-by-turn measurements. A calibration system provides evaluation of the BPM signal path and application programs.

Photographic and photometric enhancement of Lunar Orbiter products, projects A, B and C

NASA Technical Reports Server (NTRS)

1972-01-01

A detailed discussion is presented of the framelet joining, photometric data improvement, and statistical error analysis. The Lunar Orbiter film handling system, readout system, and the digitization are described, along with the technique of joining adjacent framelets by a using a digital computer. Time and cost estimates are given. The problems and techniques involved in improving the digitized data are discussed. It was found that spectacular improvements are possible. Program documentations are included.

Magnetic Field Investigation for ISEE mother and daughter spacecraft. [magnetometer design, capability, and results

NASA Technical Reports Server (NTRS)

Russell, C. T.

1981-01-01

Highlights of the design and fabrication of fluxgate magnetometers for the ISEE A and B satellites which were launched from a single launch vehicle into the same highly elliptical orbit are presented. The instrument consisted of four basic assemblies: the sensors, the drive and sense electronics, the data handling unit; and the flipper. The digital handling data handling assembly contained a digital filter that mantained a uniform transfer function for all three axes of both spacecraft. Initial studies centered on the bow shock and the magnetopause and show that both boundaries are in rapid motion. The bow shock was found to be very thin, close to an ion inertial length in thickness, but the magnetopause was much thicker than expected, about 400 to 1000 km on average. The magnetometers have each logged over 3 2/3 years of continuous operation.

Lunar gravity affects leaf movement of Arabidopsis thaliana in the International Space Station.

PubMed

Fisahn, Joachim; Klingelé, Emile; Barlow, Peter

2015-06-01

Cyclic leaf ascent and descent occur in synchrony and phase congruence with the lunisolar tidal force under a broad range of conditions. Digitized records of the vertical leaf movements of Arabidopsis thaliana were collected under space flight conditions in the International Space Station (ISS). Oscillations of leaf movements with periods of 45 and 90 min were found under light-adapted conditions, whereas in darkness, the periods were 45, 90, and 135 min. To demonstrate the close relationship between these oscillations and cyclical variations of the lunisolar gravitational force, we estimated the oscillations of the in-orbit lunisolar tide as they apply to the ISS, with the aid of the Etide software application. In general, in-orbit lunisolar gravitational profiles exhibited a periodicity of 45 min. Alignment of these in-orbit oscillations with the oscillations of Arabidopsis leaf movement revealed high degrees of synchrony and a congruence of phase. These data corroborate previous results which suggested a correlative relationship and a possible causal link between leaf movement rhythms obtained on ground and the rhythmic variation of the lunisolar tidal force.

75 FR 7370 - Closed Captioning of Video Programming; Closed Captioning Requirements for Digital Television...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-02-19

... 08-255] Closed Captioning of Video Programming; Closed Captioning Requirements for Digital Television... Captioning of Video Programming; Closed Captioning Requirements for Digital Television Receivers, Declaratory... 1594, January 13, 2009, is effective February 19, 2010. Video programming distributors must comply with...

The AD and ELENA orbit, trajectory and intensity measurement systems

NASA Astrophysics Data System (ADS)

Marco-Hernández, R.; Alves, D.; Angoletta, M. E.; Marqversen, O.; Molendijk, J.; Oponowicz, E.; Ruffieux, R.; Sánchez-Quesada, J.; SØby, L.

2017-07-01

This paper describes the new Antiproton Decelerator (AD) orbit measurement system and the Extra Low ENergy Antiproton ring (ELENA) orbit, trajectory and intensity measurement system. The AD machine at European Organization for Nuclear Research (CERN) is presently being used to decelerate antiprotons from 3.57 GeV/c to 100 MeV/c for matter vs anti-matter comparative studies. The ELENA machine, presently under commissioning, has been designed to provide an extra deceleration stage down to 13.7 MeV/c. The AD orbit system is based on 32 horizontal and 27 vertical electrostatic Beam Position Monitor (BPM) fitted with existing low noise front-end amplifiers while the ELENA system consists of 24 \\gls{BPM}s equipped with new low-noise head amplifiers. In both systems the front-end amplifiers generate a difference (delta) and a sum (sigma) signal which are sent to the digital acquisition system, placed tens of meters away from the AD or ELENA rings, where they are digitized and further processed. The beam position is calculated by dividing the difference signal by the sum signal either using directly the raw digitized data for measuring the turn-by-turn trajectory in the ELENA system or after down-mixing the signals to baseband for the orbit measurement in both machines. The digitized sigma signal will be used in the ELENA system to calculate the bunched beam intensity and the Schottky parameters with coasting beam after passing through different signal processing chain. The digital acquisition arrangement for both systems is based on the same hardware, also used in the ELENA Low Level Radio Frequency (LLRF) system, which follows the VME Switched Serial (VXS) enhancement of the Versa Module Eurocard 64x extension (VME64x) standard and includes VITA 57 standard Field Programmable Gate Array Mezzanine Card (FMC). The digital acquisition Field Programmable Gate Array (FPGA) and Digital Signal Processor (DSP) firmware shares many common functionalities with the LLRF system but has been tailored for this measurement application in particular. Specific control and acquisition software has been developed for these systems. Both systems are installed in AD and ELENA. The AD orbit system currently measures the orbit in AD while the ELENA system is being used in the commissioning of the ELENA ring.

Rescue and Calibration of NIMBUS 1-4 IR Film Products, 1964 TO 1972

NASA Astrophysics Data System (ADS)

Morgan, T.; Campbell, G. G.

2017-12-01

Digital data exists from the high resolution infrared instruments on Nimbus 1 to 4 for about 1/4 of the possible orbits for parts of 1964, 1966, 1969 and 1970. We are now digitizing and navigating 35 mm film products from those instruments into digital files. Some of those orbits overlap with the digital data so we can "calibrate" the gray scale pictures into temperatures by comparison. Then that calibration can be extended to orbits with no digital data. This greatly improves the coverage of the night time IR view of the earth. Ultimately these data will be inserted into the NASA archive for general use. We will review our progress on this project and discuss an error estimate for the calibration of the HRIR (High Resolution Infrared Radiometer) data from Nimbus 1, 2 and 3 as well as the THIR (Thermal Infrared Radiometer) data on Nimbus 4. These more complete Infrared views of the Earth provide the opportunity to better understand the weather in this period. Comparisons will be made with pre-satellite era reanalysis products.

Characterization and Design of Digital Pointing Subsystem for Optical Communication Demonstrator

NASA Technical Reports Server (NTRS)

Racho, C.; Portillo, A.

1998-01-01

The Optical Communications Demonstrator (OCD) is a laboratory-based lasercom demonstration terminal designed to validate several key technologies, including beacon acquisition, high bandwidth tracking, precision bearn pointing, and point-ahead compensation functions. It has been under active development over the past few years. The instrument uses a CCD array detector for both spatial acquisition and high-bandwidth tracking, and a fiber coupled laser transmitter. The array detector tracking concept provides wide field-of-view acquisition and permits effective platform jitter compensation and point-ahead control using only one steering mirror. This paper describes the detailed design and characterization of the digital control loop system which includes the Fast Steering Mirror (FSM), the CCD image tracker, and the associated electronics. The objective is to improve the overall system performance using laboratory measured data. The. design of the digital control loop is based on a linear time invariant open loop model. The closed loop performance is predicted using the theoretical model. With the digital filter programmed into the OCD control software, data is collected to verify the predictions. This paper presents the results of the, system modeling and performance analysis. It has been shown that measurement data closely matches theoretical predictions. An important part of the laser communication experiment is the ability of FSM to track the laser beacon within the. required tolerances. The pointing must be maintained to an accuracy that is much smaller than the transmit signal beamwidth. For an earth orbit distance, the system must be able to track the receiving station to within a few microradians. The failure. to do so will result in a severely degraded system performance.

Geodesy and cartography of the Martian satellites

NASA Technical Reports Server (NTRS)

Batson, R. M.; Edwards, Kathleen; Duxbury, T. C.

1992-01-01

The difficulties connected with conventional maps of Phobos and Deimos are largely overcome by producing maps in digital forms, i.e., by projecting Viking Orbiter images onto a global topographic model made from collections of radii derived by photogrammetry. The resulting digital mosaics are then formatted as arrays of body-centered latitudes, longitudes, radii, and brightness values of Viking Orbiter images. The Phobos mapping described was done with Viking Orbiter data. Significant new coverage was obtained by the Soviet Phobos mission. The mapping of Deimos is in progress, using the techniques developed for Phobos.

Guidance system operations plan for manned LM earth orbital and lunar missions using program luminary 1E. Section 2: Data links

NASA Technical Reports Server (NTRS)

Hamilton, M. H.

1972-01-01

Data links for the guidance system of manned lunar module orbital and lunar missions are presented. Subjects discussed are: (1) digital uplink to lunar module, (2) lunar module liftoff time increment, (3) lunar module contiguous block update, (4) lunar module scatter update, (5) lunar module digital downlink, and (6) absolute addresses for update program.

Measuring the Orbital Period of the Moon Using a Digital Camera

ERIC Educational Resources Information Center

Hughes, Stephen W.

2006-01-01

A method of measuring the orbital velocity of the Moon around the Earth using a digital camera is described. Separate images of the Moon and stars taken 24 hours apart were loaded into Microsoft PowerPoint and the centre of the Moon marked on each image. Four stars common to both images were connected together to form a "home-made" constellation.…

Physical Meaning of Virtual Kohn-Sham Orbitals and Orbital Energies: An Ideal Basis for the Description of Molecular Excitations.

PubMed

van Meer, R; Gritsenko, O V; Baerends, E J

2014-10-14

In recent years, several benchmark studies on the performance of large sets of functionals in time-dependent density functional theory (TDDFT) calculations of excitation energies have been performed. The tested functionals do not approximate exact Kohn-Sham orbitals and orbital energies closely. We highlight the advantages of (close to) exact Kohn-Sham orbitals and orbital energies for a simple description, very often as just a single orbital-to-orbital transition, of molecular excitations. Benchmark calculations are performed for the statistical average of orbital potentials (SAOP) functional for the potential [J. Chem. Phys. 2000, 112, 1344; 2001, 114, 652], which approximates the true Kohn-Sham potential much better than LDA, GGA, mGGA, and hybrid potentials do. An accurate Kohn-Sham potential does not only perform satisfactorily for calculated vertical excitation energies of both valence and Rydberg transitions but also exhibits appealing properties of the KS orbitals including occupied orbital energies close to ionization energies, virtual-occupied orbital energy gaps very close to excitation energies, realistic shapes of virtual orbitals, leading to straightforward interpretation of most excitations as single orbital transitions. We stress that such advantages are completely lost in time-dependent Hartree-Fock and partly in hybrid approaches. Many excitations and excitation energies calculated with local density, generalized gradient, and hybrid functionals are spurious. There is, with an accurate KS, or even the LDA or GGA potentials, nothing problematic about the "band gap" in molecules: the HOMO-LUMO gap is close to the first excitation energy (the optical gap).

Determination of use of a real time tone tracker to obtain same beam interferometry data

NASA Technical Reports Server (NTRS)

Nandi, S.; Border, J. S.; Folkner, W. M.

1993-01-01

The radio metric tracking technique known as Same-Beam Interferometry (SBI) has been shown to improve orbit determination accuracy for the Magellan and Pioneer 12 orbiter. Previous efforts to explore the technique were carried out by making open loop recordings of the carrier signals from the two spacecraft and extracting their phases through post processing. This paper reports on the use of a closed loop receiver to simultaneously measure the carrier signals from two spacecraft in order to produce SBI data in near real time. The Experiment Tone Tracker is a digital closed loop receiver installed in two of NASA's Deep Space Network stations which can simultaneously extract the phase of up to eight tones. The receivers were used in late September and October of 1992 to collect Doppler and SBI data from Pioneer 12 and Magellan. The demise of the Pionner 12 on October 8th during the start-up phase of our tests precluded the collection of an extensive set of SBI data, however two passes of SBI and several arcs of single spacecraft Doppler data were recorded. The SBI data were analyzed and determined to have statistical errors consistent with error models and similar to open loop data.

Kepler-36: a pair of planets with neighboring orbits and dissimilar densities.

PubMed

Carter, Joshua A; Agol, Eric; Chaplin, William J; Basu, Sarbani; Bedding, Timothy R; Buchhave, Lars A; Christensen-Dalsgaard, Jørgen; Deck, Katherine M; Elsworth, Yvonne; Fabrycky, Daniel C; Ford, Eric B; Fortney, Jonathan J; Hale, Steven J; Handberg, Rasmus; Hekker, Saskia; Holman, Matthew J; Huber, Daniel; Karoff, Christopher; Kawaler, Steven D; Kjeldsen, Hans; Lissauer, Jack J; Lopez, Eric D; Lund, Mikkel N; Lundkvist, Mia; Metcalfe, Travis S; Miglio, Andrea; Rogers, Leslie A; Stello, Dennis; Borucki, William J; Bryson, Steve; Christiansen, Jessie L; Cochran, William D; Geary, John C; Gilliland, Ronald L; Haas, Michael R; Hall, Jennifer; Howard, Andrew W; Jenkins, Jon M; Klaus, Todd; Koch, David G; Latham, David W; MacQueen, Phillip J; Sasselov, Dimitar; Steffen, Jason H; Twicken, Joseph D; Winn, Joshua N

2012-08-03

In the solar system, the planets' compositions vary with orbital distance, with rocky planets in close orbits and lower-density gas giants in wider orbits. The detection of close-in giant planets around other stars was the first clue that this pattern is not universal and that planets' orbits can change substantially after their formation. Here, we report another violation of the orbit-composition pattern: two planets orbiting the same star with orbital distances differing by only 10% and densities differing by a factor of 8. One planet is likely a rocky "super-Earth," whereas the other is more akin to Neptune. These planets are 20 times more closely spaced and have a larger density contrast than any adjacent pair of planets in the solar system.

CSM docked DAP/orbital assembly bending interaction-axial case

NASA Technical Reports Server (NTRS)

Turnbull, J. F.; Jones, J. E.

1972-01-01

A digital autopilot which can provide attitude control for the entire Skylab orbital assembly using the service module reaction control jets is described. An important consideration is the potential interaction of the control system with the bending modes of the orbital assembly. Two aspects of this potential interaction were considered. The first was the possibility that bending induced rotations feeding back through the attitude sensor into the control system could produce an instability or self-sustained oscillation. The second was whether the jet activity commanded by the control system could produce excessive loads at any of the critical load points of the orbital assembly. Both aspects were studied by using analytic techniques and by running simulations on the all-digital simulator.

MUCHFUSS - Massive Unseen Companions to Hot Faint Underluminous Stars from SDSS

NASA Astrophysics Data System (ADS)

Geier, S.; Schaffenroth, V.; Hirsch, H.; Tillich, A.; Heber, U.; Maxted, P. F. L.; Østensen, R. H.; Barlow, B. N.; O'Toole, S. J.; Kupfer, T.; Marsh, T.; Gänsicke, B.; Napiwotzki, R.; Cordes, O.; Müller, S.; Classen, L.; Ziegerer, E.; Drechsel, H.

2012-06-01

The project Massive Unseen Companions to Hot Faint Underluminous Stars from SDSS (MUCHFUSS) aims at finding hot subdwarf stars with massive compact companions (white dwarfs with masses M>1.0 M⊙, neutron stars or black holes). The existence of such systems is predicted by binary evolution calculations and some candidate systems have been found. We identified ≃1100 hot subdwarf stars from the Sloan Digital Sky Survey (SDSS). Stars with high velocities have been reobserved and individual SDSS spectra have been analysed. About 70 radial velocity variable subdwarfs have been selected as good candidates for follow-up time resolved spectroscopy to derive orbital parameters and photometric follow-up to search for features like eclipses in the light curves. Up to now we found nine close binary sdBs with short orbital periods ranging from ≃0.07 d to 1.5 d. Two of them are eclipsing binaries with companions that are most likely of substellar nature.

Pluto and Charon in Color: Pluto-Centric View Animation

NASA Image and Video Library

2015-06-11

The first color movies from NASA's New Horizons mission show Pluto and its largest moon, Charon, and the complex orbital dance of the two bodies, known as a double planet. A near-true color movie were assembled from images made in three colors -- blue, red and near-infrared -- by the Multispectral Visible Imaging Camera on the instrument known as Ralph. The images were taken on nine different occasions from May 29-June 3, 2015. The movie is "Pluto-centric," meaning that Charon is shown as it moves in relation to Pluto, which is digitally centered in the movie. (The North Pole of Pluto is at the top.) Pluto makes one turn around its axis every 6 days, 9 hours and 17.6 minutes-the same amount of time that Charon rotates in its orbit. Looking closely at the images in this movie, one can detect a regular shift in Pluto's brightness-due to the brighter and darker terrains on its differing faces. http://photojournal.jpl.nasa.gov/catalog/PIA19689

Guidance system operations plan for manned cm earth orbital and lunar missions using program Colossus 3. Section 2: Data links

NASA Technical Reports Server (NTRS)

Hamilton, M. H.

1971-01-01

The data links for use with the guidance system operations plan for manned command module earth orbital and lunar missions using program Colossus 3 are presented. The subjects discussed are: (1) digital uplink to CMC, (2) command module contiguous block update, (3) CMC retrofire external data update, (4) CMC digital downlink, and (5) CMC entry update.

Close up view of the Orbiter Discovery in the Orbiter ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Close up view of the Orbiter Discovery in the Orbiter Processing Facility at Kennedy Space Center. The view is a detail of the aft, starboard landing gear and a general view of the Thermal Protection System tiles around the landing-gear housing. - Space Transportation System, Orbiter Discovery (OV-103), Lyndon B. Johnson Space Center, 2101 NASA Parkway, Houston, Harris County, TX

PLT Polansky looks through hatch at U.S. Laboratory / Destiny module

NASA Image and Video Library

2001-02-11

STS98-E-5115 (11 February 2001) --- This medium shot, photographed with a digital still camera, shows STS-98 pilot Mark L. Polansky looking through the observation port on Unity's closed hatch to the newly attached Destiny laboratory. The crews of Atlantis and the International Space Station opened the laboratory shortly after this photo was made on Feb. 11; and the astronauts and cosmonauts spent the first full day of what are planned to be years of work ahead inside the orbiting science and command center. Station commander William M. (Bill) Shepherd opened the Destiny hatch, and he and shuttle commander Kenneth D. Cockrell ventured inside at 8:38 a.m. (CST), Feb. 11. As depicted in subsequent digital images in this series, members of both crews went to work quickly inside the new module, activating air systems, fire extinguishers, alarm systems, computers and internal communications. The crew also continued equipment transfers from the shuttle to the station.

CDR Shepherd looks in hatch at U.S. Laboratory / Destiny module

NASA Image and Video Library

2001-02-11

STS98-E-5121 (11 February 2001) --- This digital still camera shot shows Expedition One commander William M. (Bill) Shepherd looking through the observation port on Unity's closed hatch to the newly attached Destiny laboratory. Astronauts Kenneth D. Cockrell and Mark L. Polansky appear at the left and right edges, respectively. The crews of Atlantis and the International Space Station opened the laboratory shortly after this photo was made on Feb. 11, and the astronauts and cosmonauts spent the first full day of what are planned to be years of work ahead inside the orbiting science and command center. Shepherd opened the Destiny hatch, and he and shuttle commander Cockrell ventured inside at 8:38 a.m. (CST), Feb. 11. As depicted in subsequent digital images in this series, members of both crews went to work quickly inside the new module, activating air systems, fire extinguishers, alarm systems, computers and internal communications. The crew also continued equipment transfers from the shuttle to the station.

Astronauts Cockrell, Shepherd and Polansky prior to opening hatch

NASA Image and Video Library

2001-02-11

STS98-E-5123 (11 February 2001) --- This digital still camera shot shows STS-98 mission commander Kenneth D. Cockrell (from left), Expedition One commander William M. (Bill) Shepherd and STS-98 pilot Mark L. Polansky pausing at Unity's closed hatch to the newly attached Destiny laboratory. The crews of Atlantis and the International Space Station opened the laboratory shortly after this photo was made on Feb. 11; and the astronauts and cosmonauts spent the first full day of what are planned to be years of work ahead inside the orbiting science and command center. Shepherd opened the Destiny hatch, and he and shuttle commander Cockrell ventured inside at 8:38 a.m. (CST), Feb. 11. As depicted in subsequent digital images in this series, members of both crews went to work quickly inside the new module, activating air systems, fire extinguishers, alarm systems, computers and internal communications. The crew also continued equipment transfers from the shuttle to the station.

An automated mapping satellite system ( Mapsat).

USGS Publications Warehouse

Colvocoresses, A.P.

1982-01-01

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

Single Event Upset Analysis: On-orbit performance of the Alpha Magnetic Spectrometer Digital Signal Processor Memory aboard the International Space Station

NASA Astrophysics Data System (ADS)

Li, Jiaqiang; Choutko, Vitaly; Xiao, Liyi

2018-03-01

Based on the collection of error data from the Alpha Magnetic Spectrometer (AMS) Digital Signal Processors (DSP), on-orbit Single Event Upsets (SEUs) of the DSP program memory are analyzed. The daily error distribution and time intervals between errors are calculated to evaluate the reliability of the system. The particle density distribution of International Space Station (ISS) orbit is presented and the effects from the South Atlantic Anomaly (SAA) and the geomagnetic poles are analyzed. The impact of solar events on the DSP program memory is carried out combining data analysis and Monte Carlo simulation (MC). From the analysis and simulation results, it is concluded that the area corresponding to the SAA is the main source of errors on the ISS orbit. Solar events can also cause errors on DSP program memory, but the effect depends on the on-orbit particle density.

LETTER TO THE EDITOR: Quantum manifestations of closed orbits in the photoexcitation scaled spectrum of the hydrogen atom in crossed fields

NASA Astrophysics Data System (ADS)

Rao, Jianguo; Delande, D.; Taylor, K. T.

2001-06-01

The scaled photoexcitation spectrum of the hydrogen atom in crossed electric and magnetic fields has been obtained by means of accurate quantum mechanical calculation using a new algorithm. Closed orbits in the corresponding classical system have also been obtained, using a new, efficient and practical searching procedure. Two new classes of closed orbit have been identified. Fourier transforming each photoexcitation quantum spectrum to yield a plot against scaled action has allowed direct comparison between peaks in such plots and the scaled action values of closed orbits. Excellent agreement has been found with all peaks assigned.

A digital audio/video interleaving system. [for Shuttle Orbiter

NASA Technical Reports Server (NTRS)

Richards, R. W.

1978-01-01

A method of interleaving an audio signal with its associated video signal for simultaneous transmission or recording, and the subsequent separation of the two signals, is described. Comparisons are made between the new audio signal interleaving system and the Skylab Pam audio/video interleaving system, pointing out improvements gained by using the digital audio/video interleaving system. It was found that the digital technique is the simplest, most effective and most reliable method for interleaving audio and/or other types of data into the video signal for the Shuttle Orbiter application. Details of the design of a multiplexer capable of accommodating two basic data channels, each consisting of a single 31.5-kb/s digital bit stream are given. An adaptive slope delta modulation system is introduced to digitize audio signals, producing a high immunity of work intelligibility to channel errors, primarily due to the robust nature of the delta-modulation algorithm.

Stability of Multi-Planet Systems Orbiting in the Alpha Centauri AB System

NASA Astrophysics Data System (ADS)

Lissauer, Jack

2018-04-01

We evaluate how closely-spaced planetary orbits in multiple planet systems can be and still survive for billion-year timescales within the alpha Centauri AB system. Although individual planets on nearly circular, coplanar orbits can survive throughout the habitable zones of both stars, perturbations from the companion star imply that the spacing of such planets in multi-planet systems must be significantly larger than the spacing of similar systems orbiting single stars in order to be long-lived. Because the binary companion induces a forced eccentricity upon circumstellar planets, stable orbits with small initial eccentricities aligned with the binary orbit are possible to slightly larger initial semimajor axes than are initially circular orbits. Initial eccentricities close to the appropriate forced eccentricity can have a much larger affect on how closely planetary orbits can be spaced, on how many planets may remain in the habitable zones, although the required spacing remains significantly higher than for planets orbiting single stars.

ORBITAL DISTRIBUTIONS OF CLOSE-IN PLANETS AND DISTANT PLANETS FORMED BY SCATTERING AND DYNAMICAL TIDES

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

Nagasawa, M.; Ida, S., E-mail: nagasawa.m.ad@m.titech.ac.jp

2011-12-01

We investigated the formation of close-in planets (hot Jupiters) by a combination of mutual scattering, Kozai effect, and tidal circularization, through N-body simulations of three gas giant planets, and compared the results with discovered close-in planets. We found that in about 350 cases out of 1200 runs ({approx}30%), the eccentricity of one of the planets is excited highly enough for tidal circularization by mutual close scatterings followed by secular effects due to outer planets, such as the Kozai mechanism, and the planet becomes a close-in planet through the damping of eccentricity and semimajor axis. The formation probability of close-in planetsmore » by such scattering is not affected significantly by the effect of the general relativity and inclusion of inertial modes in addition to fundamental modes in the tides. Detailed orbital distributions of the formed close-in planets and their counterpart distant planets in our simulations were compared with observational data. We focused on the possibility for close-in planets to retain non-negligible eccentricities ({approx}> 0.1) on timescales of {approx}10{sup 9} yr and have high inclinations, because close-in planets in eccentric or highly inclined orbits have recently been discovered. In our simulations we found that as many as 29% of the close-in planets have retrograde orbits, and the retrograde planets tend to have small eccentricities. On the other hand, eccentric close-in planets tend to have orbits of small inclinations.« less

A simple method to design non-collision relative orbits for close spacecraft formation flying

NASA Astrophysics Data System (ADS)

Jiang, Wei; Li, JunFeng; Jiang, FangHua; Bernelli-Zazzera, Franco

2018-05-01

A set of linearized relative motion equations of spacecraft flying on unperturbed elliptical orbits are specialized for particular cases, where the leader orbit is circular or equatorial. Based on these extended equations, we are able to analyze the relative motion regulation between a pair of spacecraft flying on arbitrary unperturbed orbits with the same semi-major axis in close formation. Given the initial orbital elements of the leader, this paper presents a simple way to design initial relative orbital elements of close spacecraft with the same semi-major axis, thus preventing collision under non-perturbed conditions. Considering the mean influence of J 2 perturbation, namely secular J 2 perturbation, we derive the mean derivatives of orbital element differences, and then expand them to first order. Thus the first order expansion of orbital element differences can be added to the relative motion equations for further analysis. For a pair of spacecraft that will never collide under non-perturbed situations, we present a simple method to determine whether a collision will occur when J 2 perturbation is considered. Examples are given to prove the validity of the extended relative motion equations and to illustrate how the methods presented can be used. The simple method for designing initial relative orbital elements proposed here could be helpful to the preliminary design of the relative orbital elements between spacecraft in a close formation, when collision avoidance is necessary.

Close up detail of the underside of the Orbiter Discovery ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Close up detail of the underside of the Orbiter Discovery in the Vehicle Assembly Building at NASA's Kennedy Space Center. This view is from underneath the aft section looking forward. It is a close-up view of the High-temperature Reusable Surface Insulation tiles showing the wear patterns from the heat of reentry, consequential replacement of worn and damaged tiles. The wear and replacement patters are unique to each Orbiter which can serve as their particular "fingerprint". - Space Transportation System, Orbiter Discovery (OV-103), Lyndon B. Johnson Space Center, 2101 NASA Parkway, Houston, Harris County, TX

Close up oblique view aft, port side of the Orbiter ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Close up oblique view aft, port side of the Orbiter Discovery in the Vehicle Assembly Building at NASA's Kennedy Space Center. This view shows a close up of the elevons and underside of the port wing. On the aft fuselage in the approximate center rift of the image is the T-0 umbilical panels. - Space Transportation System, Orbiter Discovery (OV-103), Lyndon B. Johnson Space Center, 2101 NASA Parkway, Houston, Harris County, TX

Digital image transformation and rectification of spacecraft and radar images

NASA Technical Reports Server (NTRS)

Wu, S. S. C.

1985-01-01

The application of digital processing techniques to spacecraft television pictures and radar images is discussed. The use of digital rectification to produce contour maps from spacecraft pictures is described; images with azimuth and elevation angles are converted into point-perspective frame pictures. The digital correction of the slant angle of radar images to ground scale is examined. The development of orthophoto and stereoscopic shaded relief maps from digital terrain and digital image data is analyzed. Digital image transformations and rectifications are utilized on Viking Orbiter and Lander pictures of Mars.

A New Era in Geodesy and Cartography: Implications for Landing Site Operations

NASA Technical Reports Server (NTRS)

Duxbury, T. C.

2001-01-01

The Mars Global Surveyor (MGS) Mars Orbiter Laser Altimeter (MOLA) global dataset has ushered in a new era for Mars local and global geodesy and cartography. These data include the global digital terrain model (Digital Terrain Model (DTM) radii), the global digital elevation model (Digital Elevation Model (DEM) elevation with respect to the geoid), and the higher spatial resolution individual MOLA ground tracks. Currently there are about 500,000,000 MOLA points and this number continues to grow as MOLA continues successful operations in orbit about Mars, the combined processing of radiometric X-band Doppler and ranging tracking of MGS together with millions of MOLA orbital crossover points has produced global geodetic and cartographic control having a spatial (latitude/longitude) accuracy of a few meters and a topographic accuracy of less than 1 meter. This means that the position of an individual MOLA point with respect to the center-of-mass of Mars is know to an absolute accuracy of a few meters. The positional accuracy of this point in inertial space over time is controlled by the spin rate uncertainty of Mars which is less than 1 km over 10 years that will be improved significantly with the next landed mission.

The self-calibration method for multiple systems at the CHARA Array

NASA Astrophysics Data System (ADS)

O'Brien, David

The self-calibration method, a new interferometric technique at the CHARA Array, has been used to derive orbits for several spectroscopic binaries. This method uses the wide component of a hierarchical triple system to calibrate visibility measurements of the triple's close binary system. At certain baselines and separations, the calibrator in one of these systems can be observed quasi-simultaneously with the target. Depending on the orientation of the CHARA observation baseline relative to the orientation of the wide orbit of the triple system, separated fringe packets may be observed. A sophisticated observing scheme must be put in place to ensure the existence of separated fringe packets on nights of observation. Prior to the onset of this project, the reduction of separated fringe packet data had never included the goal of deriving visibilities for both fringe packets, so new data reduction software has been written. Visibilities obtained with separated fringe packet data for the target close binary are run through both Monte Carlo simulations and grid search programs in order to determine the best-fit orbital elements of the close binary. Several targets have been observed in this fashion, and orbits have been derived for seven targets, including three new orbits. Derivation of the orbit of the close pair in a triple system allows for the calculation of the mutual inclination, which is the angle between the planes of the wide and close orbit. Knowledge of this quantity may give insight into the formation processes that create multiple star systems. INDEX WORDS: Long-baseline interferometry, Self calibration, Separated fringe packets, Triple systems, Close binaries, Multiple systems, Orbital parameters, Near-infrared interferometry

Closed almost-periodic orbits in semiclassical quantization of generic polygons

PubMed

Biswas

2000-05-01

Periodic orbits are the central ingredients of modern semiclassical theories and corrections to these are generally nonclassical in origin. We show here that, for the class of generic polygonal billiards, the corrections are predominantly classical in origin owing to the contributions from closed almost-periodic (CAP) orbit families. Furthermore, CAP orbit families outnumber periodic families but have comparable weights. They are hence indispensable for semiclassical quantization.

Late type close binary system CM Dra

NASA Astrophysics Data System (ADS)

Kalomeni, Belinda

2015-08-01

In this study, we present new observations of the close binary system CM Dra. We analyzed all the available data of the system and estimated the physical parameters of the system stars highly accurately. Using the newly obtained parameters the distance of the system is determined to be 11.6 pc. A possible giant planet orbiting the close binary system has been detected. This orbital period would likely make it one of the longest known orbital period planet.

Model-independent and fast determination of optical functions in storage rings via multiturn and closed-orbit data

NASA Astrophysics Data System (ADS)

Riemann, Bernard; Grete, Patrick; Weis, Thomas

2011-06-01

Multiturn (or turn-by-turn) data acquisition has proven to be a new source of direct measurements for Twiss parameters in storage rings. On the other hand, closed-orbit measurements are a long-known tool for analyzing closed-orbit perturbations with conventional beam position monitor (BPM) systems and are necessarily available at every storage ring. This paper aims at combining the advantages of multiturn measurements and closed-orbit data. We show that only two multiturn BPMs and four correctors in one localized drift space in the storage ring (diagnostic drift) are sufficient for model-independent and absolute measuring of β and φ functions at all BPMs, including the conventional ones, instead of requiring all BPMs being equipped with multiturn electronics.

Stability of Multi-Planet Systems in the Alpha Centauri System

NASA Technical Reports Server (NTRS)

Lissauer, Jack J.

2017-01-01

We evaluate the extent of the regions within the alpha Centauri AB star system where small planets are able to orbit for billion-year timescales (Quarles & Lissauer 2016, Astron. J. 151, 111), as well as how closely-spaced planetary orbits can be within those regions in which individual planets can survive. Although individual planets on low inclination, low eccentricity, orbits can survive throughout the habitable zones of both stars, perturbations from the companion star imply that the spacing of planets in multi-planet systems within the habitable zones of each star must be significantly larger than the spacing of similar multi-planet systems orbiting single stars in order to be long-lived. Because the binary companion induces a forced eccentricity upon the orbits of planets in orbit around either star, appropriately-aligned circumstellar orbits with small initial eccentricities are stable to slightly larger initial semimajor axes than are initially circular orbits. Initial eccentricities close to forced eccentricities can have a much larger affect on how closely planetary orbits can be spaced, and therefore on how many planets may remain in the habitable zones, although the required spacing remains significantly higher than for planets orbiting single stars.

Mechanical systems with closed orbits on manifolds of revolution

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

Kudryavtseva, E A; Fedoseev, D A

We study natural mechanical systems describing the motion of a particle on a two-dimensional Riemannian manifold of revolution in the field of a central smooth potential. We obtain a classification of Riemannian manifolds of revolution and central potentials on them that have the strong Bertrand property: any nonsingular (that is, not contained in a meridian) orbit is closed. We also obtain a classification of manifolds of revolution and central potentials on them that have the 'stable' Bertrand property: every parallel is an 'almost stable' circular orbit, and any nonsingular bounded orbit is closed. Bibliography: 14 titles.

Generation and performance assessment of the global TanDEM-X digital elevation model

NASA Astrophysics Data System (ADS)

Rizzoli, Paola; Martone, Michele; Gonzalez, Carolina; Wecklich, Christopher; Borla Tridon, Daniela; Bräutigam, Benjamin; Bachmann, Markus; Schulze, Daniel; Fritz, Thomas; Huber, Martin; Wessel, Birgit; Krieger, Gerhard; Zink, Manfred; Moreira, Alberto

2017-10-01

The primary objective of the TanDEM-X mission is the generation of a global, consistent, and high-resolution digital elevation model (DEM) with unprecedented global accuracy. The goal is achieved by exploiting the interferometric capabilities of the two twin SAR satellites TerraSAR-X and TanDEM-X, which fly in a close orbit formation, acting as an X-band single-pass interferometer. Between December 2010 and early 2015 all land surfaces have been acquired at least twice, difficult terrain up to seven or eight times. The acquisition strategy, data processing, and DEM calibration and mosaicking have been systematically monitored and optimized throughout the entire mission duration, in order to fulfill the specification. The processing of all data has finally been completed in September 2016 and this paper reports on the final performance of the TanDEM-X global DEM and presents the acquisition and processing strategy which allowed to obtain the final DEM quality. The results confirm the outstanding global accuracy of the delivered product, which can be now utilized for both scientific and commercial applications.

Astronaut Shepherd looks in hatch at U.S. Laboratory / Destiny module

NASA Image and Video Library

2001-02-11

STS98-E-5120 (11 February 2001) --- This digital still camera shot shows Expedition One commander William M. (Bill) Shepherd looking through the portal on Unity's closed hatch to the newly attached Destiny laboratory. (Note: Astronauts Kenneth D. Cockrell and Mark L. Polansky appear at the left and right edges, respectively, but could possibly be cropped out in some views). The crews of Atlantis and the International Space Station opened the laboratory shortly after this photo was made on February 11; and the astronauts and cosmonauts spent the first full day of what are planned to be years of work ahead inside the orbiting science and command center. Shepherd opened the Destiny hatch, and he and shuttle commander Cockrell ventured inside at 8:38 a.m. (CST), Feb. 11. As depicted in subsequent digital images in this series, members of both crews went to work quickly inside the new module, activating air systems, fire extinguishers, alarm systems, computers and internal communications. The crew also continued equipment transfers from the shuttle to the station.

Removal of instrument signature from Mariner 9 television images of Mars

NASA Technical Reports Server (NTRS)

Green, W. B.; Jepsen, P. L.; Kreznar, J. E.; Ruiz, R. M.; Schwartz, A. A.; Seidman, J. B.

1975-01-01

The Mariner 9 spacecraft was inserted into orbit around Mars in November 1971. The two vidicon camera systems returned over 7300 digital images during orbital operations. The high volume of returned data and the scientific objectives of the Television Experiment made development of automated digital techniques for the removal of camera system-induced distortions from each returned image necessary. This paper describes the algorithms used to remove geometric and photometric distortions from the returned imagery. Enhancement processing of the final photographic products is also described.

Analysis of close encounters with Ganymede and Callisto using a genetic n-body algorithm

NASA Astrophysics Data System (ADS)

Winter, Philip M.; Galiazzo, Mattia A.; Maindl, Thomas I.

2018-05-01

In this work we describe a genetic algorithm which is used in order to study orbits of minor bodies in the frames of close encounters. We find that the algorithm in combination with standard orbital numerical integrators can be used as a good proxy for finding typical orbits of minor bodies in close encounters with planets and even their moons, saving a lot of computational time compared t0 long-term orbital numerical integrations. Here, we study close encounters of Centaurs with Callisto and Ganymede in particular. We also perform n-body numerical simulations for comparison. We find typical impact velocities to be between v rel = 20[v esc ] and v rel = 30[v esc ] for Ganymede and between v rel = 25[v esc ] and v rel = 35[v esc ] for Callisto.

Hypersonic Navier Stokes Comparisons to Orbiter Flight Data

NASA Technical Reports Server (NTRS)

Campbell, Charles H.; Nompelis, Ioannis; Candler, Graham; Barnhart, Michael; Yoon, Seokkwan

2009-01-01

Hypersonic chemical nonequilibrium simulations of low earth orbit entry flow fields are becoming increasingly commonplace as software and computational capabilities become more capable. However, development of robust and accurate software to model these environments will always encounter a significant barrier in developing a suite of high quality calibration cases. The US3D hypersonic nonequilibrium Navier Stokes analysis capability has been favorably compared to a number of wind tunnel test cases. Extension of the calibration basis for this software to Orbiter flight conditions will provide an incremental increase in confidence. As part of the Orbiter Boundary Layer Transition Flight Experiment and the Hypersonic Thermodynamic Infrared Measurements project, NASA is performing entry flight testing on the Orbiter to provide valuable aerothermodynamic heating data. An increase in interest related to orbiter entry environments is resulting from this activity. With the advent of this new data, comparisons of the US3D software to the new flight testing data is warranted. This paper will provide information regarding the framework of analyses that will be applied with the US3D analysis tool. In addition, comparisons will be made to entry flight testing data provided by the Orbiter BLT Flight Experiment and HYTHIRM projects. If data from digital scans of the Orbiter windward surface become available, simulations will also be performed to characterize the difference in surface heating between the CAD reference OML and the digitized surface provided by the surface scans.

Three Conservation Applications of Astronaut Photographs of Earth: Tidal Flat Loss (Japan), Elephant Impacts on Vegetation (Botswana), and Seagrass and Mangrove Monitoring (Australia)

NASA Technical Reports Server (NTRS)

Lulla, Kamlesh P.; Robinson, Julie A.; Minorukashiwagi; Maggiesuzuki; Duanenellis, M.; Bussing, Charles E.; Leelong, W. J.; McKenzie, Andlen J.

2000-01-01

NASA photographs taken from low Earth orbit can provide information relevant to conservation biology. This data source is now more accessible due to improvements in digitizing technology, Internet file transfer, and availability of image processing software. We present three examples of conservation-related projects that benefited from using orbital photographs. (1) A time series of photographs from the Space Shuttle showing wetland conversion in Japan was used as a tool for communicating about the impacts of tidal flat loss. Real-time communication with astronauts about a newsworthy event resulted in acquiring current imagery. These images and the availability of other high resolution digital images from NASA provided timely public information on the observed changes. (2) A Space Shuttle photograph of Chobe National Park in Botswana was digitally classified and analyzed to identify the locations of elephant-impacted woodland. Field validation later confirmed that areas identified on the image showed evidence of elephant impacts. (3) A summary map from intensive field surveys of seagrasses in Shoalwater Bay, Australia was used as reference data for a supervised classification of a digitized photograph taken from orbit. The classification was able to distinguish seagrasses, sediments and mangroves with accuracy approximating that in studies using other satellite remote sensing data. Orbital photographs are in the public domain and the database of nearly 400,000 photographs from the late 1960s to the present is available at a single searchable location on the Internet. These photographs can be used by conservation biologists for general information about the landscape and in quantitative applications.

Extraction of topography from side-looking satellite systems - A case study with SPOT simulation data

NASA Technical Reports Server (NTRS)

Ungar, Stephen G.; Merry, Carolyn J.; Mckim, Harlan L.; Irish, Richard; Miller, Michael S.

1988-01-01

A simulated data set was used to evaluate techniques for extracting topography from side-looking satellite systems for an area of northwest Washington state. A negative transparency orthophotoquad was digitized at a spacing of 85 microns, resulting in an equivalent ground distance of 9.86 m between pixels and a radiometric resolution of 256 levels. A bilinear interpolation was performed on digital elevation model data to generate elevation data at a 9.86-m resolution. The nominal orbital characteristics and geometry of the SPOT satellite were convoluted with the data to produce simulated panchromatic HRV digital stereo imagery for three different orbital paths and techniques for reconstructing topographic data were developed. Analyses with the simulated HRV data and other data sets show that the method is effective.

Computer-generated formulas for three-center nuclear-attraction integrals (electrostatic potential) for Slater-type orbitals

NASA Technical Reports Server (NTRS)

Jones, H. W.

1984-01-01

The computer-assisted C-matrix, Loewdin-alpha-function, single-center expansion method in spherical harmonics has been applied to the three-center nuclear-attraction integral (potential due to the product of separated Slater-type orbitals). Exact formulas are produced for 13 terms of an infinite series that permits evaluation to ten decimal digits of an example using 1s orbitals.

Communications satellite systems capacity analysis

NASA Technical Reports Server (NTRS)

Browne, L.; Hines, T.; Tunstall, B.

1982-01-01

Analog and digital modulation techniques are compared with regard to efficient use of the geostationary orbit by communications satellites. Included is the definition of the baseline systems (both space and ground segments), determination of interference susceptibility, calculation of orbit spacing, and evaluation of relative costs. It is assumed that voice or TV is communicated at 14/11 GHz using either FM or QPSK modulation. Both the Fixed-Satellite Service and the Broadcasting-Satellite Service are considered. For most of the cases examined the digital approach requires a satellite spacing less than or equal to that required by the analog approach.

Impact detections of temporarily captured natural satellites

NASA Astrophysics Data System (ADS)

Clark, David; Spurný, Pavel; Wiegert, Paul; Brown, Peter G.; Borovicha, Jiri; Tagliaferri, Ed; Shrbeny, Lukas

2016-10-01

Temporarily Captured Orbiters (TCOs) are Near-Earth Objects (NEOs) which make a few orbits of Earth before returning to heliocentric orbits. Only one TCO has been observed to date, 2006 RH120, captured by Earth for one year before escaping. Detailed modeling predicts capture should occur from the NEO population predominantly through the Sun-Earth L1 and L2 points, with 1% of TCOs impacting Earth and approximately 0.1% of meteoroids being TCOs. Although thousands of meteoroid orbits have been measured, none until now have conclusively exhibited TCO behaviour, largely due to difficulties in measuring initial meteoroid speed with sufficient precision. We report on a precise meteor observation of January 13, 2014 by a new generation of all-sky fireball digital camera systems operated in the Czech Republic as part of the European Fireball Network, providing the lowest natural object entry speed observed in decades long monitoring by networks world-wide. Modeling atmospheric deceleration and fragmentation yields an initial mass of ~5 kg and diameter of 15 cm, with a maximum Earth-relative velocity just over 11.0 km/s. Spectral observations prove its natural origin. Back-integration across observational uncertainties yields a 92 - 98% probability of TCO behaviour, with close lunar dynamical interaction. The capture duration varies across observational uncertainties from 48 days to 5+ years. We also report on two low-speed impacts recorded by US Government sensors, and we examine Prairie Network event PN39078 from 1965 having an extremely low entry speed of 10.9 km/s. In these cases uncertainties in measurement and origin make TCO designation uncertain.

An orbit fit to likely Hermus Stream stars

NASA Astrophysics Data System (ADS)

Martin, Charles; Amy, Paul M.; Newberg, Heidi Jo; Shelton, Siddhartha; Carlin, Jeffrey L.; Beers, Timothy C.; Denissenkov, Pavel; Willett, Benjamin A.

2018-06-01

We selected blue horizontal branch (BHB) stars within the expected distance range and sky position of the Hermus Stream from Data Release 10 of the Sloan Digital Sky Survey. We identify a moving group of 19 BHB stars that are concentrated within two degrees of the Hermus Stream, between 10 and 14 kpc from the Sun. The concentration in velocity is inconsistent with a Gaussian distribution with 98 per cent confidence (2.33 sigma). The stars in the moving group have line-of-sight velocities of vgsr ˜ 50 km s-1, a velocity dispersion of σv ≲ 11 km s-1, a line-of-sight depth of ˜1 kpc, and a metallicity of [Fe/H] = -2.1 ± 0.4. The best-fitting orbit has a perigalacticon of ˜4 kpc, apogalacticon of ˜17 kpc, orbital period of ˜247 Myr, eccentricity e = 0.62, and inclination i ˜ 75° from b = 90°. The BHB stars in the stream are estimated to be 12 Gyr old. An N-body simulation of a mass-follows-light ultrafaint dwarf galaxy with mass 106 M⊙ and radius 40 pc is consistent with the observed properties. The properties of the identified moving group of 19 BHB stars are close enough to those of the Hermus Stream (which is traced predominantly in turnoff stars) that we find it likely that they are associated. If that is the case, then our orbit fit would imply that there is no relationship between the Hermus and Phoenix streams, as previously proposed.

Space Operations Center, Shuttle Interaction Study. Volume 2: Appendices, Book 1 of 2

NASA Technical Reports Server (NTRS)

1981-01-01

The feasibility of shuttle orbiter docking to the Space Operations Center (SOC) is studied. The in-orbit relative motion of the free flying orbiter and SOC was simulated, accounting for the Orbiter RCS and digital autopilot (DAP) systems, orbital mechanics, center of gravity offset of the orbiter docking port, aero and gravity gradient effects, and other pertinent natural and man-made phenomena. Since there is no specified flight path and procedure for docking, terminal closure sensitivities were investigated. Orbiter approach direction, Orbiter approach attitude out of plane, DAP thruster compensation mode, final ballistic docking distance and time to dock, rate and excursion attitude deadbands, and selection of various thruster combinations (differing from nominal) for translational pulses are considered.

Dynamics and Control of Tethered Antennas/Reflectors in Orbit

DTIC Science & Technology

1992-02-01

reflector system. The optimal linear quadratic Gaussian (LQG) digital con- trol of the orbiting tethered antenna/reflector system is analyzed. The...flexibility of both the antenna and the tether are included in this high order system model. With eight point actuators optimally positioned together with...able to maintain satisfactory pointing accuracy for low and moderate altitude orbits under the influence of solar pressure. For the higher altitudes a

Transforming System Engineering through Model-Centric Engineering

DTIC Science & Technology

2015-01-31

story that is being applied and evolved on Jupiter Europa Orbiter (JEO) project [75], and we summarize some aspects of it here, because it goes beyond...JEO Jupiter Europa Orbiter project at NASA/JPL JSF Joint Strike Fighter JPL Jet Propulsion Laboratory of NASA Linux An operating system created by...Adaptation of Flight-Critical Systems, Digital Avionics Systems Conference, 2009. [75] Rasumussen, R., R. Shishko, Jupiter Europa Orbiter Architecture

A Physical Interpretation of the Titius-Bode Rule and Its Connection to the Closed Orbits of Bertrand's Theorem

NASA Technical Reports Server (NTRS)

Christodoulou, Dimitris M.; Kazanas, Demosthenes

2017-01-01

We consider the geometric Titius-Bode rule for the semimajor axes of planetary orbits. We derive an equivalent rule for the midpoints of the segments between consecutive orbits along the radial direction and we interpret it physically in terms of the work done in the gravitational field of the Sun by particles whose orbits are perturbed around each planetary orbit. On such energetic grounds, it is not surprising that some exoplanets in multiple-planet extrasolar systems obey the same relation. However, it is surprising that this simple interpretation of the Titius-Bode rule also reveals new properties of the bound closed orbits predicted by Bertrand's theorem, which has been known since 1873.

A physical interpretation of the Titius-Bode rule and its connection to the closed orbits of Bertrandʼs theorem

NASA Astrophysics Data System (ADS)

Christodoulou, Dimitris M.; Kazanas, Demosthenes

2017-12-01

We consider the geometric Titius-Bode rule for the semimajor axes of planetary orbits. We derive an equivalent rule for the midpoints of the segments between consecutive orbits along the radial direction and we interpret it physically in terms of the work done in the gravitational field of the Sun by particles whose orbits are perturbed around each planetary orbit. On such energetic grounds, it is not surprising that some exoplanets in multiple-planet extrasolar systems obey the same relation. However, it is surprising that this simple interpretation of the Titius-Bode rule also reveals new properties of the bound closed orbits predicted by Bertrand’s theorem, which has been known since 1873.

Bandwidth controller for phase-locked-loop

NASA Technical Reports Server (NTRS)

Brockman, Milton H. (Inventor)

1992-01-01

A phase locked loop utilizing digital techniques to control the closed loop bandwidth of the RF carrier phase locked loop in a receiver provides high sensitivity and a wide dynamic range for signal reception. After analog to digital conversion, a digital phase locked loop bandwidth controller provides phase error detection with automatic RF carrier closed loop tracking bandwidth control to accommodate several modes of transmission.

Mapping and localization for extraterrestrial robotic explorations

NASA Astrophysics Data System (ADS)

Xu, Fengliang

In the exploration of an extraterrestrial environment such as Mars, orbital data, such as high-resolution imagery Mars Orbital Camera-Narrow Angle (MOC-NA), laser ranging data Mars Orbital Laser Altimeter (MOLA), and multi-spectral imagery Thermal Emission Imaging System (THEMIS), play more and more important roles. However, these remote sensing techniques can never replace the role of landers and rovers, which can provide a close up and inside view. Similarly, orbital mapping can not compete with ground-level close-range mapping in resolution, precision, and speed. This dissertation addresses two tasks related to robotic extraterrestrial exploration: mapping and rover localization. Image registration is also discussed as an important aspect for both of them. Techniques from computer vision and photogrammetry are applied for automation and precision. Image registration is classified into three sub-categories: intra-stereo, inter-stereo, and cross-site, according to the relationship between stereo images. In the intra-stereo registration, which is the most fundamental sub-category, interest point-based registration and verification by parallax continuity in the principal direction are proposed. Two other techniques, inter-scanline search with constrained dynamic programming for far range matching and Markov Random Field (MRF) based registration for big terrain variation, are explored as possible improvements. Creating using rover ground images mainly involves the generation of Digital Terrain Model (DTM) and ortho-rectified map (orthomap). The first task is to derive the spatial distribution statistics from the first panorama and model the DTM with a dual polynomial model. This model is used for interpolation of the DTM, using Kriging in the close range and Triangular Irregular Network (TIN) in the far range. To generate a uniformly illuminated orthomap from the DTM, a least-squares-based automatic intensity balancing method is proposed. Finally a seamless orthomap is constructed by a split-and-merge technique: the mapped area is split or subdivided into small regions of image overlap, and then each small map piece was processed and all of the pieces are merged together to form a seamless map. Rover localization has three stages, all of which use a least-squares adjustment procedure: (1) an initial localization which is accomplished by adjustment over features common to rover images and orbital images, (2) an adjustment of image pointing angles at a single site through inter and intra-stereo tie points, and (3) an adjustment of the rover traverse through manual cross-site tie points. The first stage is based on adjustment of observation angles of features. The second stage and third stage are based on bundle-adjustment. In the third-stage an incremental adjustment method was proposed. Automation in rover localization includes automatic intra/inter-stereo tie point selection, computer-assisted cross-site tie point selection, and automatic verification of accuracy. (Abstract shortened by UMI.)

Stanford automatic photogrammetry research

NASA Technical Reports Server (NTRS)

Quam, L. H.; Hannah, M. J.

1974-01-01

A feasibility study on the problem of computer automated aerial/orbital photogrammetry is documented. The techniques investigated were based on correlation matching of small areas in digitized pairs of stereo images taken from high altitude or planetary orbit, with the objective of deriving a 3-dimensional model for the surface of a planet.

Data processing system for the intensity monitoring spectrometer flown on the Orbiting Geophysical Observatory-F (OGO-F) satellite

NASA Technical Reports Server (NTRS)

Cronin, A. G.; Delaney, J. R.

1973-01-01

The system is discussed which was developed to process digitized telemetry data from the intensity monitoring spectrometer flown on the Orbiting Geophysical Observatory (OGO-F) Satellite. Functional descriptions and operating instructions are included for each program in the system.

Hypervelocity Impact Test Fragment Modeling: Modifications to the Fragment Rotation Analysis and Lightcurve Code

NASA Technical Reports Server (NTRS)

Gouge, Michael F.

2011-01-01

Hypervelocity impact tests on test satellites are performed by members of the orbital debris scientific community in order to understand and typify the on-orbit collision breakup process. By analysis of these test satellite fragments, the fragment size and mass distributions are derived and incorporated into various orbital debris models. These same fragments are currently being put to new use using emerging technologies. Digital models of these fragments are created using a laser scanner. A group of computer programs referred to as the Fragment Rotation Analysis and Lightcurve code uses these digital representations in a multitude of ways that describe, measure, and model on-orbit fragments and fragment behavior. The Dynamic Rotation subroutine generates all of the possible reflected intensities from a scanned fragment as if it were observed to rotate dynamically while in orbit about the Earth. This calls an additional subroutine that graphically displays the intensities and the resulting frequency of those intensities as a range of solar phase angles in a Probability Density Function plot. This document reports the additions and modifications to the subset of the Fragment Rotation Analysis and Lightcurve concerned with the Dynamic Rotation and Probability Density Function plotting subroutines.

Reexamination of the calculation of two-center, two-electron integrals over Slater-type orbitals. II. Neumann expansion of the exchange integrals

NASA Astrophysics Data System (ADS)

Lesiuk, Michał; Moszynski, Robert

2014-12-01

In this paper we consider the calculation of two-center exchange integrals over Slater-type orbitals (STOs). We apply the Neumann expansion of the Coulomb interaction potential and consider calculation of all basic quantities which appear in the resulting expression. Analytical closed-form equations for all auxiliary quantities have already been known but they suffer from large digital erosion when some of the parameters are large or small. We derive two differential equations which are obeyed by the most difficult basic integrals. Taking them as a starting point, useful series expansions for small parameter values or asymptotic expansions for large parameter values are systematically derived. The resulting expansions replace the corresponding analytical expressions when the latter introduce significant cancellations. Additionally, we reconsider numerical integration of some necessary quantities and present a new way to calculate the integrand with a controlled precision. All proposed methods are combined to lead to a general, stable algorithm. We perform extensive numerical tests of the introduced expressions to verify their validity and usefulness. Advances reported here provide methodology to compute two-electron exchange integrals over STOs for a broad range of the nonlinear parameters and large angular momenta.

Design, Development and Testing of the Miniature Autonomous Extravehicular Robotic Camera (Mini AERCam) Guidance, Navigation and Control System

NASA Technical Reports Server (NTRS)

Wagenknecht, J.; Fredrickson, S.; Manning, T.; Jones, B.

2003-01-01

Engineers at NASA Johnson Space Center have designed, developed, and tested a nanosatellite-class free-flyer intended for future external inspection and remote viewing of human spaceflight activities. The technology demonstration system, known as the Miniature Autonomous Extravehicular Robotic Camera (Mini AERCam), has been integrated into the approximate form and function of a flight system. The primary focus has been to develop a system capable of providing external views of the International Space Station. The Mini AERCam system is spherical-shaped and less than eight inches in diameter. It has a full suite of guidance, navigation, and control hardware and software, and is equipped with two digital video cameras and a high resolution still image camera. The vehicle is designed for either remotely piloted operations or supervised autonomous operations. Tests have been performed in both a six degree-of-freedom closed-loop orbital simulation and on an air-bearing table. The Mini AERCam system can also be used as a test platform for evaluating algorithms and relative navigation for autonomous proximity operations and docking around the Space Shuttle Orbiter or the ISS.

Geomagnetic cutoffs: A review for space dosimetry applications

NASA Astrophysics Data System (ADS)

Smart, D. F.; Shea, M. A.

1994-10-01

The earth's magnetic field acts as a shield against charged particle radiation from interplanetary space, technically described as the geomagnetic cutoff. The cutoff rigidity problem (except for the dipole special case) has 'no solution in closed form'. The dipole case yields the Stormer equation which has been repeatedly applied to the earth in hopes of providing useful approximations of cutoff rigidities. Unfortunately the earth's magnetic field has significant deviations from dipole geometry, and the Stormer cutoffs are not adequate for most applications. By application of massive digital computer power it is possible to determine realistic geomagnetic cutoffs derived from high order simulation of the geomagnetic field. Using this technique, 'world-grids' of directional cutoffs for the earth's surface and for a limited number of satellite altitudes have been derived. However, this approach is so expensive and time comsuming it is impractical for most spacecraft orbits, and approximations must be used. The world grids of cutoff rigidities are extensively used as lookup tables, normalization points and interpolation aids to estimate the effective geomagnetic cutoff rigidity of a specific location in space. We review the various options for estimating the cutoff rigidity for earth-orbiting satellites.

Optical measurements of the mirrors and of the interferential filter of the Metis coronagraph on Solar Orbiter

NASA Astrophysics Data System (ADS)

Sandri, P.; Sarra, P.; Radaelli, P.; Morea, D.; Melich, R.; Berlicki, A.; Antonucci, E.; Castronuovo, M. M.; Fineschi, S.; Naletto, G.; Nicolini, G.; Romoli, M.

2017-08-01

The paper describes the wavefront error measurements of the concave ellipsoidal mirrors M1 and M2, of the concave spherical mirror M0 and of the flat interferential filter IF of the Metis coronagraph. Metis is an inverted occultation coronagraph on board of the ESA Solar Orbiter mission providing a broad-band imaging of the full corona in linearly polarized visible-light (580 - 640 nm) and a narrow-band imaging of the full corona in the ultraviolet Lyman α (121.6 nm). Metis will observe the solar outer atmosphere from a close distance to the Sun as 0.28 A.U. and from up to 35deg out-of-ecliptic. The measurements of wavefront error of the mirrors and of the interferential filter of Metis have been performed in a ISO5 clean room both at component level and at assembly level minimizing, during the integration, the stress introduced by the mechanical hardware. The wavefront error measurements have been performed with a digital interferometer for mirrors M0, M1 and M2 and with a Shack-Hartmann wavefront sensor for the interferential filter.

Wobbly Planet Orbital Schematic Illustration

NASA Image and Video Library

2014-02-04

This illustration shows the unusual orbit of planet Kepler-413b around a close pair of orange and red dwarf stars. The planet 66-day orbit is tilted 2.5 degrees with respect to the plane of the binary stars orbit.

Digital image transformation and rectification of spacecraft and radar images

USGS Publications Warehouse

Wu, S.S.C.

1985-01-01

Digital image transformation and rectification can be described in three categories: (1) digital rectification of spacecraft pictures on workable stereoplotters; (2) digital correction of radar image geometry; and (3) digital reconstruction of shaded relief maps and perspective views including stereograms. Digital rectification can make high-oblique pictures workable on stereoplotters that would otherwise not accommodate such extreme tilt angles. It also enables panoramic line-scan geometry to be used to compile contour maps with photogrammetric plotters. Rectifications were digitally processed on both Viking Orbiter and Lander pictures of Mars as well as radar images taken by various radar systems. By merging digital terrain data with image data, perspective and three-dimensional views of Olympus Mons and Tithonium Chasma, also of Mars, are reconstructed through digital image processing. ?? 1985.

The Capture of Interstellar Dust: The Pure Poynting-Robertson Case

NASA Technical Reports Server (NTRS)

Jackson, A. A.

2001-01-01

Ulysses and Galileo spacecraft have discovered interstellar dust particles entering the solar system. In general, particles trajectories not altered by Lorentz forces or radiation pressure should encounter the sun on open orbits. Under Newtonian forces alone these particles return to the interstellar medium. Dissipative forces, such as Poynting Robertson (PR) and corpuscular drag and non-dissipative Lorentz forces can modify open orbits to become closed. In particular, it is possible for the orbits of particles that pass close to the Sun to become closed due to PR drag. Further, solar irradiation will cause modification of the size of the dust particle by evaporation. The combination of these processes gives rise a class of capture orbits and bound orbits with evaporation. Considering only the case of pure PR drag a minimum impact parameter is derived for initial capture by Poynting-Robertson drag. Orbits in the solar radiation field are computed numerically accounting for evaporation with optical and material properties for ideal interstellar particles modeled. The properties of this kind of particle capture are discussed for the Sun but is applicable to other stars.

Design of a digital voice data compression technique for orbiter voice channels

NASA Technical Reports Server (NTRS)

1975-01-01

Candidate techniques were investigated for digital voice compression to a transmission rate of 8 kbps. Good voice quality, speaker recognition, and robustness in the presence of error bursts were considered. The technique of delayed-decision adaptive predictive coding is described and compared with conventional adaptive predictive coding. Results include a set of experimental simulations recorded on analog tape. The two FM broadcast segments produced show the delayed-decision technique to be virtually undegraded or minimally degraded at .001 and .01 Viterbi decoder bit error rates. Preliminary estimates of the hardware complexity of this technique indicate potential for implementation in space shuttle orbiters.

KOI2138 -- a Spin-Orbit Aligned Intermediate Period Super-Earth

NASA Astrophysics Data System (ADS)

Barnes, Jason W.

2015-11-01

A planet's formation and evolution are encoded in spin-orbit alignment -- the planet's inclination relative to its star's equatorial plane. While the solar system's spin-orbit aligned planets indicate our own relatively quiescent history, many close-in giant planets show significant misalignment. Some planets even orbit retrograde! Hot Jupiters, then, have experienced fundamentally different histories than we experienced here in the solar system. In this presentation, I will show a new determination of the spin-orbit alignment of 2.1 REarth exoplanet candidate KOI2138. KOI2138 shows a gravity-darkened transit lightcurve that is consistent with spin-orbit alignment. This measurement is important because the only other super-Earth with an alignment determination (55 Cnc e, orbit period 0.74 days) is misaligned. With an orbital period of 23.55 days, KOI2138 is far enough from its star to avoid tidal orbit evolution. Therefore its orbit is likely primordial, and hence it may represent the tip of an iceberg of terrestrial, spin-orbit aligned planets that have histories that more closely resemble that of the solar system's terrestrial planets.

Migration of comets to near-Earth space

NASA Astrophysics Data System (ADS)

Ipatov, S. I.

The orbital evolution of more than 21000 Jupiter-crossing objects under the gravitational influence of planets was investigated. For orbits close to that of Comet 2P, the mean collision probabilities of Jupiter-crossing objects with the terrestrial planets were greater by two orders of magnitude than for some other comets. For initial orbital elements close to those of Comets 2P, 10P, 44P, and 113P, a few objects (<0.1%) got Earth-crossing orbits with semi-major axes a<2 AU and aphelion distances Q<4.2 AU and moved in such orbits for more than 1 Myr (up to tens or even hundreds of Myrs). Some of them even got inner-Earth orbits (Q<0.983 AU) and Aten orbits for millions of years. Most former trans-Neptunian objects that have typical near-Earth object orbits moved in such orbits for millions of years, so during most of this time they were extinct comets or disintegrated into mini-comets.

KENNEDY SPACE CENTER, FLA. - In the Orbiter Processing Facility, STS-114 Mission Specialist Wendy Lawrence takes a close look at the some of the tiles underneath Atlantis. Lawrence is a new addition to the mission crew. The STS-114 crew is at KSC to take part in crew equipment and orbiter familiarization.

NASA Image and Video Library

2003-10-30

KENNEDY SPACE CENTER, FLA. - In the Orbiter Processing Facility, STS-114 Mission Specialist Wendy Lawrence takes a close look at the some of the tiles underneath Atlantis. Lawrence is a new addition to the mission crew. The STS-114 crew is at KSC to take part in crew equipment and orbiter familiarization.

KENNEDY SPACE CENTER, FLA. - In the Orbiter Processing Facility, STS-114 Mission Specialist Andy Thomas takes a close look at the some of the tiles underneath Atlantis. Thomas is a new addition to the mission crew. The STS-114 crew is at KSC to take part in crew equipment and orbiter familiarization.

NASA Image and Video Library

2003-10-30

KENNEDY SPACE CENTER, FLA. - In the Orbiter Processing Facility, STS-114 Mission Specialist Andy Thomas takes a close look at the some of the tiles underneath Atlantis. Thomas is a new addition to the mission crew. The STS-114 crew is at KSC to take part in crew equipment and orbiter familiarization.

Optimal Control Strategies for Constrained Relative Orbits

DTIC Science & Technology

2007-09-01

the chief. The work assumes the Clohessy - Wiltshire closeness assump- tion between the deputy and chief is valid, however, elliptical chief orbits are...133 Appendix G. A Closed-Form Solution of the Linear Clohessy - Wiltshire Equa- tions...Counterspace . . . . . . . . . . . . . . . . . . . 1 CW Clohessy - Wiltshire . . . . . . . . . . . . . . . . . . . . . . 4 DARPA Defense Advanced Research

Astrometric Observations of Phobos and Deimos During the 1971 Opposition of Mars

DTIC Science & Technology

2014-10-06

measured with the digitizer of the Royal Observatory of Belgium and reduced through an optimal process that includes image, instrumental, and spherical...measurements of planets and satellites that will be used to compute new orbital ephemerides. Since we had demonstrated that a precise digitization and...unclassified Standard Form 298 (Rev. 8-98) Prescribed by ANSI Std Z39-18 A&A proofs: manuscript no. manuscript Fig. 1. Center of the digitization

High Resolution BPM Upgrade for the ATF Damping Ring at KEK

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

Eddy, N.; Briegel, C.; Fellenz, B.

2011-08-17

A beam position monitor (BPM) upgrade at the KEK Accelerator Test Facility (ATF) damping ring has been accomplished, carried out by a KEK/FNAL/SLAC collaboration under the umbrella of the global ILC R&D effort. The upgrade consists of a high resolution, high reproducibility read-out system, based on analog and digital down-conversion techniques, digital signal processing, and also implements a new automatic gain error correction schema. The technical concept and realization as well as results of beam studies are presented. The next generation of linear colliders require ultra-low vertical emittance of <2 pm-rad. The damping ring at the KEK Accelerator Test Facilitymore » (ATF) is designed to demonstrate this mission critical goal. A high resolution beam position monitor (BPM) system for the damping ring is one of the key tools for realizing this goal. The BPM system needs to provide two distnict measurements. First, a very high resolution ({approx}100-200nm) closed-orbit measurement which is averaged over many turns and realized with narrowband filter techniques - 'narrowband mode'. This is needed to monitor and steer the beam along an optimum orbit and to facilitate beam-based alignment to minimize non-linear field effects. Second, is the ability to make turn by turn (TBT) measurements to support optics studies and corrections necessary to achieve the design performance. As the TBT measurement necessitates a wider bandwidth, it is often referred to as 'wideband mode'. The BPM upgrade was initiated as a KEK/SLAC/FNAL collaboration in the frame of the Global Design Initiative of the International Linear Collider. The project was realized and completed using Japan-US funds with Fermilab as the core partner.« less

Orbital transfer vehicle launch operations study: Manpower summary and facility requirements, volume 5

NASA Technical Reports Server (NTRS)

1986-01-01

All manpower numbers, number of heads (by skill), serial time and manhours have been accumulated and compiled on a per subtask basis in spreadsheet format for both the ground based and the space based data flows. To aid in identifying the facility resources required to process the Ground Based Orbital Transfer Vehicle (GBOTV) and/or the space based orbital transfer vehicle (SBOTV) through the ground facilities at Kennedy Space Center (KSC), a software application package was developed using a general purpose data base management system known as Data Flex. The facility requirements are used as the basic input to this software application. The resources of the KSC facility that could be used by orbital transfer vehicle program were digitized in the same format used to identify facility requirements. The facility capabilities were digitized in this format for subsequent, automated comparative analyses. Composite facility requirements are compared to each of the baseline facility capabilities and the system generates a relative score that indicates how each facility weighs against the composite requirements in relation to the other facilities in the set.

Integrated Digital Flight Control System for the Space Shuttle Orbiter

NASA Technical Reports Server (NTRS)

1973-01-01

The objectives of the integrated digital flight control system (DFCS) is to provide rotational and translational control of the space shuttle orbiter in all phases of flight: from launch ascent through orbit to entry and touchdown, and during powered horizontal flights. The program provides a versatile control system structure while maintaining uniform communications with other programs, sensors, and control effectors by using an executive routine/functional subroutine format. The program reads all external variables at a single point, copies them into its dedicated storage, and then calls the required subroutines in the proper sequence. As a result, the flight control program is largely independent of other programs in the computer complex and is equally insensitive to characteristics of the processor configuration. The integrated structure is described of the control system and the DFCS executive routine which embodies that structure. The input and output, including jet selection are included. Specific estimation and control algorithm are shown for the various mission phases: cruise (including horizontal powered flight), entry, on-orbit, and boost. Attitude maneuver routines that interface with the DFCS are included.

Practical target location and accuracy indicator in digital close range photogrammetry using consumer grade cameras

NASA Astrophysics Data System (ADS)

Moriya, Gentaro; Chikatsu, Hirofumi

2011-07-01

Recently, pixel numbers and functions of consumer grade digital camera are amazingly increasing by modern semiconductor and digital technology, and there are many low-priced consumer grade digital cameras which have more than 10 mega pixels on the market in Japan. In these circumstances, digital photogrammetry using consumer grade cameras is enormously expected in various application fields. There is a large body of literature on calibration of consumer grade digital cameras and circular target location. Target location with subpixel accuracy had been investigated as a star tracker issue, and many target location algorithms have been carried out. It is widely accepted that the least squares models with ellipse fitting is the most accurate algorithm. However, there are still problems for efficient digital close range photogrammetry. These problems are reconfirmation of the target location algorithms with subpixel accuracy for consumer grade digital cameras, relationship between number of edge points along target boundary and accuracy, and an indicator for estimating the accuracy of normal digital close range photogrammetry using consumer grade cameras. With this motive, an empirical testing of several algorithms for target location with subpixel accuracy and an indicator for estimating the accuracy are investigated in this paper using real data which were acquired indoors using 7 consumer grade digital cameras which have 7.2 mega pixels to 14.7 mega pixels.

Close up view under the Orbiter Discovery in the Vehicle ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Close up view under the Orbiter Discovery in the Vehicle Assembly Building at NASA's Kennedy Space Center. The view is under the port wing looking forward toward the main fuselage showing a detail of the landing gear and landing gear door. This view also shows the patterns of worn and replaced High-temperature Reusable Surface Insulation tiles. - Space Transportation System, Orbiter Discovery (OV-103), Lyndon B. Johnson Space Center, 2101 NASA Parkway, Houston, Harris County, TX

Accessibility, stabilizability, and feedback control of continuous orbital transfer.

PubMed

Gurfil, Pini

2004-05-01

This paper investigates the problem of low-thrust orbital transfer using orbital element feedback from a control-theoretic standpoint, concepts of controllability, feedback stabilizability, and their interaction. The Gauss variational equations (GVEs) are used to model the state-space dynamics. First, the notion of accessibility, a weaker form of controllability, is presented. It is then shown that the GVEs are globally accessible. Based on the accessibility result, a nonlinear feedback controller is derived that asymptotically steers a vehicle from an initial elliptic Keplerian orbit to any given elliptic Keplerian orbit. The performance of the new controller is illustrated by simulating an orbital transfer between two geosynchronous Earth orbits. It is shown that the low-thrust controller requires less fuel than an impulsive maneuver for the same transfer time. Closed-form, analytic expressions for the new orbital transfer controller are given. Finally, it is proved, based on a topological nonlinear stabilizability test, that there does not exist a continuous closed-loop controller that can transfer a spacecraft to a parabolic escape trajectory.

Assessment of HRSC Digital Terrain Models Produced for the South Polar Residual Cap

NASA Astrophysics Data System (ADS)

Putri, Alfiah Rizky Diana; Sidiropoulos, Panagiotis; Muller, Jan-Peter

2017-04-01

The current Digital Terrain Models available for Mars consist of NASA MOLA (Mars Orbital Laser Altimeter) Digital Terrain Models with an average resolution of 112 m/ pixel (512 pixels/degree) for the polar region. The ESA/DLR High Resolution Stereo Camera is currently orbiting Mars and mapping its surface, 98% with resolution of ≤100 m/pixel and better and 100% at lower resolution [1]. It is possible to produce Digital Terrain Models from HRSC images using various methods. In this study, the method developed on Kim and Muller [2] which uses the VICAR open source program together with photogrammetry sofrware from DLR (Deutschen Zentrums für Luft- und Raumfahrt) with image matching based on the GOTCHA (Gruen-Otto-Chau) algorithm [3]. Digital Terrain Models have been processed over the South Pole with emphasis on areas around South Polar Residual Cap from High Resolution Stereo Camera images [4]. Digital Terrain Models have been produced for 31 orbits out of 149 polar orbits available. This study analyses the quality of the DTMs including an assessment of accuracy of elevations using the MOLA MEGDR (Mission Experiment Gridded Data Records) which has roughly 42 million MOLA PEDR (Precision Experiment Data Records) points between latitudes of 78 o -90 o S. The issues encountered in the production of Digital Terrain Models will be described and the statistical results and assessment method will be presented. The resultant DTMs will be accessible via http://i-Mars.eu/web-GIS References: [1] Neukum, G. et. al, 2004. Mars Express: The Scientific Payload pp. 17-35. [2] Kim, J.-R. and J.-P. Muller. 2009. PSS vol. 57, pp. 2095-2112. [3] Shin, D. and J.-P. Muller. 2012. Pattern Recognition, 45(10), 3795 -3809. [4] Putri, A.R. D., et al., Int. Arch. Photogramm. Remote Sens. Spatial Inf. Sci., XLI-B4, 463-469 Acknowledgements: The research leading to these results has received partial funding from the STFC "MSSL Consolidated Grant" ST/K000977/1 and partial support from the European Union's Seventh Framework Programme (FP7/2007-2013) under iMars grant agreement n ˚ 607379. The first author would like to acknowledge support for her studies from Indonesia Endowment Fund for Education (LPDP), Ministry of Finance, Republic of Indonesia. The authors would also like to thank Alexander Dumke (Freie Universitaet Berlin) for providing the EXTORI exterior orientation elements which were critical in the production of accuracy geolocations.

Interventional C-arm tomosynthesis for vascular imaging: initial results

NASA Astrophysics Data System (ADS)

Langan, David A.; Claus, Bernhard E. H.; Al Assad, Omar; Trousset, Yves; Riddell, Cyril; Avignon, Gregoire; Solomon, Stephen B.; Lai, Hao; Wang, Xin

2015-03-01

As percutaneous endovascular procedures address more complex and broader disease states, there is an increasing need for intra-procedure 3D vascular imaging. In this paper, we investigate C-Arm 2-axis tomosynthesis ("Tomo") as an alternative to C-Arm Cone Beam Computed Tomography (CBCT) for workflow situations in which the CBCT acquisition may be inconvenient or prohibited. We report on our experience in performing tomosynthesis acquisitions with a digital angiographic imaging system (GE Healthcare Innova 4100 Angiographic Imaging System, Milwaukee, WI). During a tomo acquisition the detector and tube each orbit on a plane above and below the table respectively. The tomo orbit may be circular or elliptical, and the tomographic half-angle in our studies varied from approximately 16 to 28 degrees as a function of orbit period. The trajectory, geometric calibration, and gantry performance are presented. We overview a multi-resolution iterative reconstruction employing compressed sensing techniques to mitigate artifacts associated with incomplete data reconstructions. In this work, we focus on the reconstruction of small high contrast objects such as iodinated vasculature and interventional devices. We evaluate the overall performance of the acquisition and reconstruction through phantom acquisitions and a swine study. Both tomo and comparable CBCT acquisitions were performed during the swine study thereby enabling the use of CBCT as a reference in the evaluation of tomo vascular imaging. We close with a discussion of potential clinical applications for tomo, reflecting on the imaging and workflow results achieved.

Weight-lattice discretization of Weyl-orbit functions

NASA Astrophysics Data System (ADS)

Hrivnák, Jiří; Walton, Mark A.

2016-08-01

Weyl-orbit functions have been defined for each simple Lie algebra, and permit Fourier-like analysis on the fundamental region of the corresponding affine Weyl group. They have also been discretized, using a refinement of the coweight lattice, so that digitized data on the fundamental region can be Fourier-analyzed. The discretized orbit function has arguments that are redundant if related by the affine Weyl group, while its labels, the Weyl-orbit representatives, invoke the dual affine Weyl group. Here we discretize the orbit functions in a novel way, by using the weight lattice. A cleaner theory results with symmetry between the arguments and labels of the discretized orbit functions. Orthogonality of the new discretized orbit functions is proved, and leads to the construction of unitary, symmetric matrices with Weyl-orbit-valued elements. For one type of orbit function, the matrix coincides with the Kac-Peterson modular S matrix, important for Wess-Zumino-Novikov-Witten conformal field theory.

Closedness of orbits in a space with SU(2) Poisson structure

NASA Astrophysics Data System (ADS)

Fatollahi, Amir H.; Shariati, Ahmad; Khorrami, Mohammad

2014-06-01

The closedness of orbits of central forces is addressed in a three-dimensional space in which the Poisson bracket among the coordinates is that of the SU(2) Lie algebra. In particular it is shown that among problems with spherically symmetric potential energies, it is only the Kepler problem for which all bounded orbits are closed. In analogy with the case of the ordinary space, a conserved vector (apart from the angular momentum) is explicitly constructed, which is responsible for the orbits being closed. This is the analog of the Laplace-Runge-Lenz vector. The algebra of the constants of the motion is also worked out.

Closeup view looking forward along the centerline of the Orbiter ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Close-up view looking forward along the centerline of the Orbiter Discovery looking into the payload bay. This view is a close-up view of the external airlock and the beam-truss attach structure supporting it and attaching it to the payload bay sill longerons. Also note the protective covering over the docking mechanism on top of the airlock assembly. This external airlock configuration was for mating to the International Space Station. This photograph was taken in the Orbiter Processing Facility at Kennedy Space Cente - Space Transportation System, Orbiter Discovery (OV-103), Lyndon B. Johnson Space Center, 2101 NASA Parkway, Houston, Harris County, TX

A method for volume determination of the orbit and its contents by high resolution axial tomography and quantitative digital image analysis.

PubMed Central

Cooper, W C

1985-01-01

The various congenital and acquired conditions which alter orbital volume are reviewed. Previous investigative work to determine orbital capacity is summarized. Since these studies were confined to postmortem evaluations, the need for a technique to measure orbital volume in the living state is presented. A method for volume determination of the orbit and its contents by high-resolution axial tomography and quantitative digital image analysis is reported. This procedure has proven to be accurate (the discrepancy between direct and computed measurements ranged from 0.2% to 4%) and reproducible (greater than 98%). The application of this method to representative clinical problems is presented and discussed. The establishment of a diagnostic system versatile enough to expand the usefulness of computerized axial tomography and polytomography should add a new dimension to ophthalmic investigation and treatment. Images FIGURE 8 FIGURE 9 FIGURE 10 A FIGURE 10 B FIGURE 11 A FIGURE 11 B FIGURE 12 FIGURE 13 FIGURE 14 FIGURE 15 FIGURE 16 FIGURE 17 FIGURE 18 FIGURE 19 FIGURE 20 FIGURE 21 FIGURE 22 FIGURE 23 FIGURE 24 FIGURE 25 FIGURE 26 A FIGURE 26 B FIGURE 27 FIGURE 28 FIGURE 29 FIGURE 30 FIGURE 31 FIGURE 32 PMID:3938582

International Space Station (ISS)

NASA Image and Video Library

2001-09-16

The setting sun and the thin blue airglow line at Earth's horizon was captured by the International Space Station's (ISS) Expedition Three crewmembers with a digital camera. Some of the Station's components are silhouetted in the foreground. The crew was launched aboard the Space Shuttle Orbiter Discovery STS-105 mission, on August 10, 2001, replacing the Expedition Two crew. After marning the orbiting ISS for 128 consecutive days, the three returned to Earth on December 17, 2001, aboard the STS-108 mission Space Shuttle Orbiter Endeavour.

Topographic map of part of the Kasei Valles and Sacra Fossae regions of Mars - MTM 500k 20/287E OMKT

USGS Publications Warehouse

Rosiek, Mark R.; Redding, Bonnie L.; Galuszca, Donna M.

2005-01-01

This map is part of a series of topographic maps of areas of special scientific interest on Mars. The topography was compiled photogrammetrically using Viking Orbiter stereo image pairs and photoclinometry from a Viking Orbiter image. The contour interval is 250 m. Horizontal and vertical control was established using the USGS Mars Digital Image Model 2.0 (MDIM 2.0) and data from the Mars Orbiter Laser Altimeter (MOLA).

Radar cross section measurements of a scale model of the space shuttle orbiter vehicle

NASA Technical Reports Server (NTRS)

Yates, W. T.

1978-01-01

A series of microwave measurements was conducted to determine the radar cross section of the Space Shuttle Orbiter vehicle at a frequency and at aspect angles applicable to re-entry radar acquisition and tracking. The measurements were performed in a microwave anechoic chamber using a 1/15th scale model and a frequency applicable to C-band tracking radars. The data were digitally recorded and processed to yield statistical descriptions useful for prediction of orbiter re-entry detection and tracking ranges.

Characterizing omega-limit sets which are closed orbits

NASA Astrophysics Data System (ADS)

Bautista, S.; Morales, C.

Let X be a vector field in a compact n-manifold M, n⩾2. Given Σ⊂M we say that q∈M satisfies (P) Σ if the closure of the positive orbit of X through q does not intersect Σ, but, however, there is an open interval I with q as a boundary point such that every positive orbit through I intersects Σ. Among those q having saddle-type hyperbolic omega-limit set ω(q) the ones with ω(q) being a closed orbit satisfy (P) Σ for some closed subset Σ. The converse is true for n=2 but not for n⩾4. Here we prove the converse for n=3. Moreover, we prove for n=3 that if ω(q) is a singular-hyperbolic set [C. Morales, M. Pacifico, E. Pujals, On C robust singular transitive sets for three-dimensional flows, C. R. Acad. Sci. Paris Sér. I 26 (1998) 81-86], [C. Morales, M. Pacifico, E. Pujals, Robust transitive singular sets for 3-flows are partially hyperbolic attractors or repellers, Ann. of Math. (2) 160 (2) (2004) 375-432], then ω(q) is a closed orbit if and only if q satisfies (P) Σ for some Σ closed. This result improves [S. Bautista, Sobre conjuntos hiperbólicos-singulares (On singular-hyperbolic sets), thesis Uiversidade Federal do Rio de Janeiro, 2005 (in Portuguese)] and [C. Morales, M. Pacifico, Mixing attractors for 3-flows, Nonlinearity 14 (2001) 359-378].

Dynamical evolution and chronology of the Hygiea asteroid family

NASA Astrophysics Data System (ADS)

Carruba, V.; Domingos, R. C.; Huaman, M. E.; Santos, C. R. dos; Souami, D.

2014-01-01

The asteroid (10) Hygiea is the fourth largest asteroid of the main belt, by volume and mass, and it is the largest member of its own family. Previous works investigated the long-term effects of close encounters with (10) Hygiea of asteroids in the orbital region of the family, and analysed the taxonomical and dynamical properties of members of this family. In this paper we apply the high-quality Sloan Digital Sky Survey-Moving Object Catalog data, fourth release (SDSS-MOC4) taxonomic scheme of DeMeo & Carry to members of the Hygiea family core and halo, we obtain an estimate of the minimum time and number of encounter necessary to obtain a 3σ (or 99.7 per cent) compatible frequency distribution function of changes in proper a caused by close encounters with (10) Hygiea, we study the behaviour of asteroids near secular resonance configurations, in the presence and absence of the Yarkovsky force, and obtain a first estimate of the age of the family based on orbital diffusion by the Yarkovsky and Yarkovsky-O'Keefe-Radzievsky-Paddack (YORP) effects with two methods. The Hygiea family is at least 2 Byr old, with an estimated age of T = 3200^{+380}_{-120} Myr and a relatively large initial ejection velocity field, according to the approach of Vokrouhlický et al. Surprisingly, we found that the family age can be shortened by ≃25 per cent if the dynamical mobility caused by close encounters with (10) Hygiea is also accounted for, which opens interesting new research lines for the dynamical evolution of families associated with massive bodies. In our taxonomical analysis of the Hygiea asteroid family, we also identified a new V-type candidate: the asteroid (177904) (2005 SV5). If confirmed, this could be the fourth V-type object ever to be identified in the outer main belt.

Digital data, composite video multiplexer and demultiplexer boards for an IBM PC/AT compatible computer

NASA Technical Reports Server (NTRS)

Smith, Dean Lance

1993-01-01

Work continued on the design of two IBM PC/AT compatible computer interface boards. The boards will permit digital data to be transmitted over a composite video channel from the Orbiter. One board combines data with a composite video signal. The other board strips the data from the video signal.

The payload/shuttle-data-communication-link handbook

NASA Technical Reports Server (NTRS)

1982-01-01

Communication links between the Orbiter, payloads, and ground are described: end-to-end, hardline, S-band, Ku-band, TDRSS relay, waveforms, premodulation, subcarrier modulation, carrier modulation, transmitter power, antennas, the RF channel, system noise, received signal-to-noise spectral density, carrier-tracking loop, carrier demodulation, subcarrier demodulation, digital data detection, digital data decoding, and tandem link considerations.

Star System Bonanza Illustration

NASA Image and Video Library

2014-02-27

This illustration shows the unusual orbit of planet Kepler-413b around a close pair of orange and red dwarf stars. The planet 66-day orbit is tilted 2.5 degrees with respect to the plane of the binary stars orbit.

Optimization of constellation jettisoning regards to short term collision risks

NASA Astrophysics Data System (ADS)

Handschuh, D.-DA.-A.; Bourgeois, E.

2018-04-01

The space debris problematic is directly linked to the in-orbit collision risk between artificial satellites. With the increase of the space constellation projects, a multiplication of multi-payload launches should occur. In the specific cases where many satellites are injected into orbit with the same launcher upper stage, all these objects will be placed on similar orbits, very close one from each other, at a specific moment where their control capabilities will be very limited. Under this hypothesis, it is up to the launcher operator to ensure that the simultaneous in-orbit injection is safe enough to guarantee the non-collision risk between all the objects under a ballistic hypothesis eventually considering appropriate uncertainties. The purpose of the present study is to find optimized safe separation conditions to limit the in-orbit collision risk following the injection of many objects on very close orbits in a short-delay mission.

Do Close-in Giant Planets Orbiting Evolved Stars Prefer Eccentric Orbits?

NASA Astrophysics Data System (ADS)

Grunblatt, Samuel K.; Huber, Daniel; Gaidos, Eric; Lopez, Eric D.; Barclay, Thomas; Chontos, Ashley; Sinukoff, Evan; Van Eylen, Vincent; Howard, Andrew W.; Isaacson, Howard T.

2018-07-01

The NASA Kepler and K2 Missions have recently revealed a population of transiting giant planets orbiting moderately evolved, low-luminosity red giant branch stars. Here, we present radial velocity (RV) measurements of three of these systems, revealing significantly non-zero orbital eccentricities in each case. Comparing these systems with the known planet population suggests that close-in giant planets around evolved stars tend to have more eccentric orbits than those around main sequence stars. We interpret this as tentative evidence that the orbits of these planets pass through a transient, moderately eccentric phase where they shrink faster than they circularize due to tides raised on evolved host stars. Additional RV measurements of currently known systems, along with new systems discovered by the recently launched NASA Transiting Exoplanet Survey Satellite (TESS) mission, may constrain the timescale and mass dependence of this process.

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

Petrovich, Cristobal; Rafikov, Roman; Tremaine, Scott, E-mail: cpetrovi@princeton.edu

Many exoplanets in close-in orbits are observed to have relatively high eccentricities and large stellar obliquities. We explore the possibility that these result from planet-planet scattering by studying the dynamical outcomes from a large number of orbit integrations in systems with two and three gas-giant planets in close-in orbits (0.05 AU < a < 0.15 AU). We find that at these orbital separations, unstable systems starting with low eccentricities and mutual inclinations (e ≲ 0.1, i ≲ 0.1) generally lead to planet-planet collisions in which the collision product is a planet on a low-eccentricity, low-inclination orbit. This result is inconsistentmore » with the observations. We conclude that eccentricity and inclination excitation from planet-planet scattering must precede migration of planets into short-period orbits. This result constrains theories of planet migration: the semi-major axis must shrink by 1-2 orders of magnitude without damping the eccentricity and inclination.« less

Modification of an impulse-factoring orbital transfer technique to account for orbit determination and maneuver execution errors

NASA Technical Reports Server (NTRS)

Kibler, J. F.; Green, R. N.; Young, G. R.; Kelly, M. G.

1974-01-01

A method has previously been developed to satisfy terminal rendezvous and intermediate timing constraints for planetary missions involving orbital operations. The method uses impulse factoring in which a two-impulse transfer is divided into three or four impulses which add one or two intermediate orbits. The periods of the intermediate orbits and the number of revolutions in each orbit are varied to satisfy timing constraints. Techniques are developed to retarget the orbital transfer in the presence of orbit-determination and maneuver-execution errors. Sample results indicate that the nominal transfer can be retargeted with little change in either the magnitude (Delta V) or location of the individual impulses. Additonally, the total Delta V required for the retargeted transfer is little different from that required for the nominal transfer. A digital computer program developed to implement the techniques is described.

High-Voltage, Low-Power BNC Feedthrough Terminator

NASA Technical Reports Server (NTRS)

Bearden, Douglas

2012-01-01

This innovation is a high-voltage, lowpower BNC (Bayonet Neill-Concelman) feedthrough that enables the user to terminate an instrumentation cable properly while connected to a high voltage, without the use of a voltage divider. This feedthrough is low power, which will not load the source, and will properly terminate the instrumentation cable to the instrumentation, even if the cable impedance is not constant. The Space Shuttle Program had a requirement to measure voltage transients on the orbiter bus through the Ground Lightning Measurement System (GLMS). This measurement has a bandwidth requirement of 1 MHz. The GLMS voltage measurement is connected to the orbiter through a DC panel. The DC panel is connected to the bus through a nonuniform cable that is approximately 75 ft (approximately equal to 23 m) long. A 15-ft (approximately equal to 5-m), 50-ohm triaxial cable is connected between the DC panel and the digitizer. Based on calculations and simulations, cable resonances and reflections due to mismatched impedances of the cable connecting the orbiter bus and the digitizer causes the output not to reflect accurately what is on the bus. A voltage divider at the DC panel, and terminating the 50-ohm cable properly, would eliminate this issue. Due to implementation issues, an alternative design was needed to terminate the cable properly without the use of a voltage divider. Analysis shows how the cable resonances and reflections due to the mismatched impedances of the cable connecting the orbiter bus and the digitizer causes the output not to reflect accurately what is on the bus. After simulating a dampening circuit located at the digitizer, simulations were performed to show how the cable resonances were dampened and the accuracy was improved significantly. Test cables built to verify simulations were accurate. Since the dampening circuit is low power, it can be packaged in a BNC feedthrough.

Long-term Stability of Tightly Packed Multi-planet Systems in Prograde, Coplanar, Circumstellar Orbits within the α Centauri AB System

NASA Astrophysics Data System (ADS)

Quarles, B.; Lissauer, Jack J.

2018-03-01

We perform long-term simulations, up to ten billion years, of closely spaced configurations of 2–6 planets, each as massive as the Earth, traveling on nested orbits about either stellar component in α Centauri AB. The innermost planet initially orbits at either the inner edge of its star’s empirical habitable zone (HZ) or the inner edge of its star’s conservative HZ. Although individual planets on low inclination, low eccentricity, orbits can survive throughout the HZs of both stars, perturbations from the companion star require that the minimum spacing of planets in multi-planet systems within the HZs of each star must be significantly larger than the spacing of similar multi-planet systems orbiting single stars in order to be long-lived. The binary companion induces a forced eccentricity upon the orbits of planets in orbit around either star. Planets on appropriately phased circumstellar orbits with initial eccentricities equal to their forced eccentricities can survive on more closely spaced orbits than those with initially circular orbits, although the required spacing remains higher than for planets orbiting single stars. A total of up to nine planets on nested prograde orbits can survive for the current age of the system within the empirical HZs of the two stars, with five of these orbiting α Centauri B and four orbiting α Centauri A.

The Fate of Exomoons when Planets Scatter

NASA Astrophysics Data System (ADS)

Kohler, Susanna

2018-03-01

Four examples of close-encounter outcomes: a) the moon stays in orbit around its host, b) the moon is captured into orbit around its perturber, c) and d) the moon is ejected from the system from two different starting configurations. [Adapted from Hong et al. 2018]Planet interactions are thought to be common as solar systems are first forming and settling down. A new study suggests that these close encounters could have a significant impact on the moons of giant exoplanets and they may generate a large population of free-floating exomoons.Chaos in the SystemIn the planetplanet scattering model of solar-system formation, planets are thought to initially form in closely packed systems. Over time, planets in a system perturb each other, eventually entering an instability phase during which their orbits cross and the planets experience close encounters.During this scattering process, any exomoons that are orbiting giant planets can be knocked into unstable orbits directly by close encounters with perturbing planets. Exomoons can also be disturbed if their host planets properties or orbits change as a consequence of scattering.Led by Yu-Cian Hong (Cornell University), a team of scientists has now explored the fate of exomoons in planetplanet scattering situations using a suite of N-body numerical simulations.Chances for SurvivalHong and collaborators find that the vast majority roughly 80 to 90% of exomoons around giant planets are destabilized during scattering and dont survive in their original place in the solar system. Fates of these destabilized exomoons include:moon collision with the star or a planet,moon capture by the perturbing planet,moon ejection from the solar system,ejection of the entire planetmoon system from the solar system, andmoon perturbation onto a new heliocentric orbit as a planet.Unsurprisingly, exomoons that have close-in orbits and those that orbit larger planets are the most likely to survive close encounters; as an example, exomoons on orbits similar to Jupiters Galilean satellites (i.e., orbiting at a distance of less than 4% of their host planets Hill radius) have a 2040% chance of survival.Moon initial semimajor axis vs. moon survival rate. Three of Jupiters Galilean moons are shown for reference. [Hong et al. 2018]Free-Floating MoonsAn intriguing consequence of Hong and collaborators results is the prediction of a population of free-floating exomoons that were ejected from solar systems during planetplanet scattering and now wander through the universe alone. According to the authors models, there may be as many of these free-floating exomoons as there are stars in the universe!Future surveys that search for objects using gravitational microlensing like that planned with the Wide-Field Infrared Survey Telescope (WFIRST) may be able to detect such objects down to masses of a tenth of an Earth mass. In the meantime, were a little closer to understanding the complex dynamics of early solar systems.CitationYu-Cian Hong et al 2018 ApJ 852 85. doi:10.3847/1538-4357/aaa0db

Himalayan Mtns. and Mt. Everest Earth observation taken by Dan Bursch during EXP. Four

NASA Image and Video Library

2002-03-20

ISS004-E-8852 (20 March 2002) --- Astronaut Daniel W. Bursch, flight engineer for Expedition Four aboard the International Space Station, used a digital still camera to capture this image of Mt. Everest in the Himalayan Range. The mountain is near frame center. Here are the notes Bursch added in one of his reports to ground controllers: "One morning I happened to be up early. I glanced at our world map and saw that we’d be passing near Mt Everest soon. I checked the computer, realized that we were in an attitude that would allow me to open the window shutter and there was Mt Everest! It almost seemed to jump out at me. The low sun angle (it was close to orbital sunrise) gave tremendous relief to the mountains. It was just one of those sights that will be forever burned into my brain!"

Digital controller design: Continuous and discrete describing function analysis of the IPS system

NASA Technical Reports Server (NTRS)

1977-01-01

The dynamic equations and the mathematical model of the continuous-data IPS control system are developed. The IPS model considered included one flexible body mode and was hardmounted to the Orbiter/Pallet. The model contains equations describing a torque feed-forward loop (using accelerometers as inputs) which will aid in reducing the pointing errors caused by Orbiter disturbances.

Integrated digital flight-control system for the space shuttle orbiter

NASA Technical Reports Server (NTRS)

1973-01-01

The integrated digital flight control system is presented which provides rotational and translational control of the space shuttle orbiter in all phases of flight: from launch ascent through orbit to entry and touchdown, and during powered horizontal flights. The program provides a versatile control system structure while maintaining uniform communications with other programs, sensors, and control effectors by using an executive routine/functional subroutine format. The program reads all external variables at a single point, copies them into its dedicated storage, and then calls the required subroutines in the proper sequence. As a result, the flight control program is largely independent of other programs in the GN&C computer complex and is equally insensitive to the characteristics of the processor configuration. The integrated structure of the control system and the DFCS executive routine which embodies that structure are described along with the input and output. The specific estimation and control algorithms used in the various mission phases are given.

The Dawn of Vesta Science

NASA Technical Reports Server (NTRS)

Garner, Charles E.; Rayman, Marc D.; Brophy, John R.; Mikes, Steven C.

2011-01-01

The Dawn mission is part of NASA's Discovery Program and has as its goal the scientific exploration of the two most massive main-belt asteroids, Vesta and Ceres. The Dawn spacecraft was launched from the Cape Canaveral Air Force Station on September 27, 2007 on a Delta-II 7925H-9.5 (Delta-II Heavy) rocket that placed the 1218-kg spacecraft onto an Earth-escape trajectory. On-board the spacecraft is an ion propulsion system (IPS) developed at the Jet Propulsion Laboratory which will provide a total ?V of 11.3 km/s for the heliocentric transfer to Vesta, orbit capture at Vesta, transfer between Vesta science orbits, departure and escape from Vesta, heliocentric transfer to Ceres, orbit capture at Ceres, and transfer between Ceres science orbits. Fullpower thrusting from December 2007 through October 2008 was used to successfully target a Mars gravity assist flyby in February 2009 that provided an additional ?V of 2.6 km/s. Deterministic thrusting for the heliocentric transfer to Vesta resumed in June 2009 and concluded with orbit capture at Vesta on July 16, 2011. An additional 210 hours of IPS thrusting was used to enter the first Vesta science orbit, called Survey orbit, on August 3, 2011 at an altitude of approximately 2,735 km. To date the IPS has been operated for 23,621 hours, consumed approximately 252 kg of xenon, and provided a delta-V of approximately 6.7 km/s. The IPS performance characteristics are very close to the expected performance based on analysis and testing performed pre-launch. The only significant issue in over the almost four years of IPS operations in flight was the temporary failure of a valve driver board in the Digital Control and Interface Unit-1 (DCIU-1), resulting in a loss of thrust of approximately 29 hours. Thrusting operations resumed after switching to DCIU-2, and power cycling conducted after orbit capture restored DCIU-1 to full functionality. After about three weeks of Survey orbit operations the IPS will be used to transfer the spacecraft to the other planned science orbit altitudes. After approximately one year of science operations the IPS will be used for escape from Vesta and then for thrusting to Ceres with a planned arrival date at Ceres in February 2015. This paper provides an overview of Dawn's mission objectives and the results of Dawn IPS mission operations through the start of science operations at Vesta.

The digital darkroom, part 3: digital presentations in plastic surgery.

PubMed

Galdino, G M; Chiaramonte, M; Klatsky, S A

2001-01-01

Digital technology is becoming an increasing popular format for societal and other presentations. Part 3 of The Digital Darkroom reviews the kinds of equipment available, the advantages and disadvantages of digital projection, and the most common pitfalls encountered in preparing and presenting material in digital presentations. It closes with a series of recommendations for optimizing your digital presentation and avoiding mistakes that might decrease its effectiveness.

Resonance and Capture of Jupiter Comets

NASA Astrophysics Data System (ADS)

Koon, W. S.; Lo, M. W.; Marsden, J. E.; Ross, S. D.

A number of Jupiter family comets such as Oterma and Gehrels 3 make a rapid transition from heliocentric orbits outside the orbit of Jupiter to heliocentric orbits inside the orbit of Jupiter and vice versa. During this transition, the comet can be captured temporarily by Jupiter for one to several orbits around Jupiter. The interior heliocentric orbit is typically close to the 3:2 resonance while the exterior heliocentric orbit is near the 2:3 resonance. An important feature of the dynamics of these comets is that during the transition, the orbit passes close to the libration points L_1 and L_2, two of the equilibrium points for the restricted three-body problem for the Sun-Jupiter system. Studying the libration point invariant manifold structures for L_1 and L_2 is a starting point for understanding the capture and resonance transition of these comets. For example, the recently discovered heteroclinic connection between pairs of unstable periodic orbits (one around the L_1 and the other around L_2) implies a complicated dynamics for comets in a certain energy range. Furthermore, the stable and unstable invariant manifold `tubes' associated to libration point periodic orbits, of which the heteroclinic connections are a part, are phase space conduits transporting material to and from Jupiter and between the interior and exterior of Jupiter's orbit.

Earth Observing-1 Advanced Imager Flight Performance Assessment: Investigating Dark Current Stability Over One-Half Orbit Period during the First 60 Days

NASA Technical Reports Server (NTRS)

Mendenhall, J. A.

2001-01-01

The stability of the EO-1 Advanced Land Imager dark current levels over the period of one-half orbit is investigated. A series of two-second dark current collections, over the course of 40 minutes, was performed during the first sixty days the instrument was in orbit. Analysis of this data indicates only two dark current reference periods, obtained entering and exiting eclipse, are required to remove ALI dark current offsets for 99.9% of the focal plane to within 1.5 digital numbers for any observation on the solar illuminated portion of the orbit.

Global Digital Image Mosaics of Mars: Assessment of Geodetic Accuracy

NASA Technical Reports Server (NTRS)

Kirk, R.; Archinal, B. A.; Lee, E. M.; Davies, M. E.; Colvin, T. R.; Duxbury, T. C.

2001-01-01

A revised global image mosaic of Mars (MDIM 2.0) was recently completed by USGS. Comparison with high-resolution gridded Mars Orbiter Laser Altimeter (MOLA) digital image mosaics will allow us to quantify its geodetic errors; linking the next MDIM to the MOLA data will help eliminate those errors. Additional information is contained in the original extended abstract.

Southwest Research Institute astronomer Dan Durda checks the alignment of the SWUIS-A Xybion digital

NASA Technical Reports Server (NTRS)

2002-01-01

Southwest Research Institute astronomer Dan Durda checks the alignment of the SWUIS-A Xybion digital camera mounted in the rear cockpit of a NASA Dryden F/A-18B before taking off on an astronomy mission to search for small vulcanoids (asteroids) that may be orbiting between the sun and the planet Mercury.

Tidal effects on stellar activity

NASA Astrophysics Data System (ADS)

Poppenhaeger, K.

2017-10-01

The architecture of many exoplanetary systems is different from the solar system, with exoplanets being in close orbits around their host stars and having orbital periods of only a few days. We can expect interactions between the star and the exoplanet for such systems that are similar to the tidal interactions observed in close stellar binary systems. For the exoplanet, tidal interaction can lead to circularization of its orbit and the synchronization of its rotational and orbital period. For the host star, it has long been speculated if significant angular momentum transfer can take place between the planetary orbit and the stellar rotation. In the case of the Earth-Moon system, such tidal interaction has led to an increasing distance between Earth and Moon. For stars with Hot Jupiters, where the orbital period of the exoplanet is typically shorter than the stellar rotation period, one expects a decreasing semimajor axis for the planet and enhanced stellar rotation, leading to increased stellar activity. Also excess turbulence in the stellar convective zone due to rising and subsiding tidal bulges may change the magnetic activity we observe for the host star. I will review recent observational results on stellar activity and tidal interaction in the presence of close-in exoplanets, and discuss the effects of enhanced stellar activity on the exoplanets in such systems.

Space Shuttle Projects

NASA Image and Video Library

2005-08-03

Launched on July 26, 2005 from the Kennedy Space Center in Florida, STS-114 was classified as Logistics Flight 1. Among the Station-related activities of the mission were the delivery of new supplies and the replacement of one of the orbital outpost's Control Moment Gyroscopes (CMGs). STS-114 also carried the Raffaello Multi-Purpose Logistics Module and the External Stowage Platform-2. A major focus of the mission was the testing and evaluation of new Space Shuttle flight safety, which included new inspection and repair techniques. Upon its approach to the International Space Station (ISS), the Space Shuttle Discovery underwent a photography session in order to assess any damages that may have occurred during its launch and/or journey through Space. The mission’s third and final Extra Vehicular Activity (EVA) included taking a close-up look and the repair of the damaged heat shield. Gap fillers were removed from between the orbiter’s heat-shielding tiles located on the craft’s underbelly. Never before had any repairs been done to an orbiter while still in space. Astronaut Stephen K. Robinson, STS-114 mission specialist, used the pictured still digital camera to expose a photo of his helmet visor during the EVA. Also visible in the reflection are thermal protection tiles on Discovery’s underside.

Space shuttle orbiter digital data processing system timing sensitivity analysis OFT ascent phase

NASA Technical Reports Server (NTRS)

Lagas, J. J.; Peterka, J. J.; Becker, D. A.

1977-01-01

Dynamic loads were investigated to provide simulation and analysis of the space shuttle orbiter digital data processing system (DDPS). Segments of the ascent test (OFT) configuration were modeled utilizing the information management system interpretive model (IMSIM) in a computerized simulation modeling of the OFT hardware and software workload. System requirements for simulation of the OFT configuration were defined, and sensitivity analyses determined areas of potential data flow problems in DDPS operation. Based on the defined system requirements and these sensitivity analyses, a test design was developed for adapting, parameterizing, and executing IMSIM, using varying load and stress conditions for model execution. Analyses of the computer simulation runs are documented, including results, conclusions, and recommendations for DDPS improvements.

Space shuttle main engine controller

NASA Technical Reports Server (NTRS)

Mattox, R. M.; White, J. B.

1981-01-01

A technical description of the space shuttle main engine controller, which provides engine checkout prior to launch, engine control and monitoring during launch, and engine safety and monitoring in orbit, is presented. Each of the major controller subassemblies, the central processing unit, the computer interface electronics, the input electronics, the output electronics, and the power supplies are described and discussed in detail along with engine and orbiter interfaces and operational requirements. The controller represents a unique application of digital concepts, techniques, and technology in monitoring, managing, and controlling a high performance rocket engine propulsion system. The operational requirements placed on the controller, the extremely harsh operating environment to which it is exposed, and the reliability demanded, result in the most complex and rugged digital system ever designed, fabricated, and flown.

Global search and rescue - A new concept. [orbital digital radar system with passive reflectors

NASA Technical Reports Server (NTRS)

Sivertson, W. E., Jr.

1976-01-01

A new terrestrial search and rescue concept is defined embodying the use of simple passive radiofreqeuncy reflectors in conjunction with a low earth-orbiting, all-weather, synthetic aperture radar to detect, identify, and position locate earth-bound users in distress. Users include ships, aircraft, small boats, explorers, hikers, etc. Airborne radar tests were conducted to evaluate the basic concept. Both X-band and L-band, dual polarization radars were operated simultaneously. Simple, relatively small, corner-reflector targets were successfully imaged and digital data processing approaches were investigated. Study of the basic concept and evaluation of results obtained from aircraft flight tests indicate an all-weather, day or night, global search and rescue system is feasible.

Floating-point system quantization errors in digital control systems

NASA Technical Reports Server (NTRS)

Phillips, C. L.; Vallely, D. P.

1978-01-01

This paper considers digital controllers (filters) operating in floating-point arithmetic in either open-loop or closed-loop systems. A quantization error analysis technique is developed, and is implemented by a digital computer program that is based on a digital simulation of the system. The program can be integrated into existing digital simulations of a system.

Weight-lattice discretization of Weyl-orbit functions

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

Hrivnák, Jiří, E-mail: jiri.hrivnak@fjfi.cvut.cz, E-mail: walton@uleth.ca; Walton, Mark A., E-mail: jiri.hrivnak@fjfi.cvut.cz, E-mail: walton@uleth.ca

Weyl-orbit functions have been defined for each simple Lie algebra, and permit Fourier-like analysis on the fundamental region of the corresponding affine Weyl group. They have also been discretized, using a refinement of the coweight lattice, so that digitized data on the fundamental region can be Fourier-analyzed. The discretized orbit function has arguments that are redundant if related by the affine Weyl group, while its labels, the Weyl-orbit representatives, invoke the dual affine Weyl group. Here we discretize the orbit functions in a novel way, by using the weight lattice. A cleaner theory results with symmetry between the arguments andmore » labels of the discretized orbit functions. Orthogonality of the new discretized orbit functions is proved, and leads to the construction of unitary, symmetric matrices with Weyl-orbit-valued elements. For one type of orbit function, the matrix coincides with the Kac-Peterson modular S matrix, important for Wess-Zumino-Novikov-Witten conformal field theory.« less

Geosynchronous Patrol Orbit for Space Situational Awareness

NASA Astrophysics Data System (ADS)

Thompson, B.; Kelecy, T.; Kubancik, T.; Flora, T.; Chylla, M.; Rose, D.

Applying eccentricity to a geosynchronous orbit produces both longitudinal and radial motion when viewed in Earth-fixed coordinates. An interesting family of orbits emerges, useful for “neighborhood patrol” space situational awareness and other missions. The basic result is a periodic (daily), quasielliptical, closed path around a fixed region of the geosynchronous (geo) orbit belt, keeping a sensor spacecraft in relatively close vicinity to designated geo objects. The motion is similar, in some regards, to the relative motion that may be encountered during spacecraft proximity operations, but on a much larger scale. The patrol orbit does not occupy a fixed slot in the geo belt, and the east-west motion can be combined with north-south motion caused by orbital inclination, leading to even greater versatility. Some practical uses of the geo patrol orbit include space surveillance (including catalog maintenance), and general space situational awareness. The patrol orbit offers improved, diverse observation geometry for angles-only sensors, resulting in faster, more accurate orbit determination compared to simple inclined geo orbits. In this paper, we analyze the requirements for putting a spacecraft in a patrol orbit, the unique station keeping requirements to compensate for perturbations, repositioning the patrol orbit to a different location along the geo belt, maneuvering into, around, and out of the volume for proximity operations with objects within the volume, and safe end-of-life disposal requirements.

Mathematical modeling and SAR simulation multifunction SAR technology efforts

NASA Technical Reports Server (NTRS)

Griffin, C. R.; Estes, J. M.

1981-01-01

The orbital SAR (synthetic aperture radar) simulation data was used in several simulation efforts directed toward advanced SAR development. Efforts toward simulating an operational radar, simulation of antenna polarization effects, and simulation of SAR images at serveral different wavelengths are discussed. Avenues for improvements in the orbital SAR simulation and its application to the development of advanced digital radar data processing schemes are indicated.

Tidal interactions of a Maclaurin spheroid - II. Resonant excitation of modes by a close, misaligned orbit

NASA Astrophysics Data System (ADS)

Braviner, Harry J.; Ogilvie, Gordon I.

2015-02-01

We model a tidally forced star or giant planet as a Maclaurin spheroid, decomposing the motion into the normal modes found by Bryan. We first describe the general prescription for this decomposition and the computation of the tidal power. Although this formalism is very general, forcing due to a companion on a misaligned, circular orbit is used to illustrate the theory. The tidal power is plotted for a variety of orbital radii, misalignment angles, and spheroid rotation rates. Our calculations are carried out including all modes of degree l ≤ 4, and the same degree of gravitational forcing. Remarkably, we find that for close orbits (a/R* ≈ 3) and rotational deformations that are typical of giant planets (e ≈ 0.4) the l = 4 component of the gravitational potential may significantly enhance the dissipation through resonance with surface gravity modes. There are also a large number of resonances with inertial modes, with the tidal power being locally enhanced by up to three orders of magnitude. For very close orbits (a/R* ≈ 3), the contribution to the power from the l = 4 modes is roughly the same magnitude as that due to the l = 3 modes.

Jovian Trojans: Orbital structures versus the WISE data

NASA Astrophysics Data System (ADS)

Rozehnal, Jakub; Broz, M.

2013-10-01

In this work, we study the relation between orbital characteristics of Jovian Trojans and their albedos and diameters as measured by the WISE/NEOWISE mission (Grav et al. 2011, 2012). In our previous work (Broz & Rozehnal 2011), we concluded that there is only one collisional family with parent body size larger than 100 km among Trojans, namely the Eurybates. This finding was based on the analysis of the observed size distributions, colour data from the Sloan Digital Sky Survey, and simulations of orbital evolution. The WISE albedos serve as an independent source of information which allows us to verify our previous results. We also update our database of suitable resonant elements (i.e. the libration amplidude D, eccentricity e, inclination I) of Trojans and we look for new (to-be-discovered) clusters by the Hierarchical Clustering Method. Using the WISE diameters, we can construct more precise size-frequency distributions of Trojans in both the leading/trailing clouds which we compare to SFD of the cluster(s) mentioned above. We then prepare a collisional model (based on the Boulder code, Morbidelli et al. 2009). Initial conditions of our model are based on an assumption that the Trojans were captured from a destabilised transplanetary disc while Jupiter jumped during its close encounter with a Neptune-mass planet - the so-called "jump capture" (Nesvorny et al. 2013). Within the framework of this model we try to constrain the age of the Eurybates family. The work of MB was supported by grant GACR 13-013085 of the Czech Science Foundation and the Research Programme MSM0021620860 of the Czech Ministry of Education.

Closing the Digital Divide: Education Telecommunications Systems and Possibilities in Western Australia

ERIC Educational Resources Information Center

Trinidad, Sue

2007-01-01

The research reported in this paper considers the current telecommunications network for the three education systems of state, independent and catholic schools in Western Australia as well as drawing on the personal experiences of teachers in these systems as the government attempts to close the digital divide with its Networking the Nation…

Close up view of the Commander's Seat on the Flight ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Close up view of the Commander's Seat on the Flight Deck of the Orbiter Discovery. It appears the Orbiter is in the roll out / launch pad configuration. A protective cover is over the Rotational Hand Controller to protect it during the commander's ingress. Most notable in this view are the Speed Brake/Thrust Controller in the center right in this view and the Translational Hand Controller in the center top of the view. This image was taken at Kennedy Space Center. - Space Transportation System, Orbiter Discovery (OV-103), Lyndon B. Johnson Space Center, 2101 NASA Parkway, Houston, Harris County, TX

Angles-only relative orbit determination in low earth orbit

NASA Astrophysics Data System (ADS)

Ardaens, Jean-Sébastien; Gaias, Gabriella

2018-06-01

The paper provides an overview of the angles-only relative orbit determination activities conducted to support the Autonomous Vision Approach Navigation and Target Identification (AVANTI) experiment. This in-orbit endeavor was carried out by the German Space Operations Center (DLR/GSOC) in autumn 2016 to demonstrate the capability to perform spaceborne autonomous close-proximity operations using solely line-of-sight measurements. The images collected onboard have been reprocessed by an independent on-ground facility for precise relative orbit determination, which served as ultimate instance to monitor the formation safety and to characterize the onboard navigation and control performances. During two months, several rendezvous have been executed, generating a valuable collection of images taken at distances ranging from 50 km to only 50 m. Despite challenging experimental conditions characterized by a poor visibility and strong orbit perturbations, angles-only relative positioning products could be continuously derived throughout the whole experiment timeline, promising accuracy at the meter level during the close approaches. The results presented in the paper are complemented with former angles-only experience gained with the PRISMA satellites to better highlight the specificities induced by different orbits and satellite designs.

Transiting circumbinary planets Kepler-34 b and Kepler-35 b

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

Welsh, William F.; Orosz, Jerome A.; Carter, Joshua A.

Most Sun-like stars in the Galaxy reside in gravitationally-bound pairs of stars called 'binary stars'. While long anticipated, the existence of a 'circumbinary planet' orbiting such a pair of normal stars was not definitively established until the discovery of Kepler-16. Incontrovertible evidence was provided by the miniature eclipses ('transits') of the stars by the planet. However, questions remain about the prevalence of circumbinary planets and their range of orbital and physical properties. Here we present two additional transiting circumbinary planets, Kepler-34 and Kepler-35. Each is a low-density gas giant planet on an orbit closely aligned with that of its parentmore » stars. Kepler-34 orbits two Sun-like stars every 289 days, while Kepler-35 orbits a pair of smaller stars (89% and 81% of the Sun's mass) every 131 days. Due to the orbital motion of the stars, the planets experience large multi-periodic variations in incident stellar radiation. The observed rate of circumbinary planets implies > ~1% of close binary stars have giant planets in nearly coplanar orbits, yielding a Galactic population of at least several million.« less

Tidal evolution of close binary asteroid systems

NASA Astrophysics Data System (ADS)

Taylor, Patrick A.; Margot, Jean-Luc

2010-12-01

We provide a generalized discussion of tidal evolution to arbitrary order in the expansion of the gravitational potential between two spherical bodies of any mass ratio. To accurately reproduce the tidal evolution of a system at separations less than 5 times the radius of the larger primary component, the tidal potential due to the presence of a smaller secondary component is expanded in terms of Legendre polynomials to arbitrary order rather than truncated at leading order as is typically done in studies of well-separated system like the Earth and Moon. The equations of tidal evolution including tidal torques, the changes in spin rates of the components, and the change in semimajor axis (orbital separation) are then derived for binary asteroid systems with circular and equatorial mutual orbits. Accounting for higher-order terms in the tidal potential serves to speed up the tidal evolution of the system leading to underestimates in the time rates of change of the spin rates, semimajor axis, and mean motion in the mutual orbit if such corrections are ignored. Special attention is given to the effect of close orbits on the calculation of material properties of the components, in terms of the rigidity and tidal dissipation function, based on the tidal evolution of the system. It is found that accurate determinations of the physical parameters of the system, e.g., densities, sizes, and current separation, are typically more important than accounting for higher-order terms in the potential when calculating material properties. In the scope of the long-term tidal evolution of the semimajor axis and the component spin rates, correcting for close orbits is a small effect, but for an instantaneous rate of change in spin rate, semimajor axis, or mean motion, the close-orbit correction can be on the order of tens of percent. This work has possible implications for the determination of the Roche limit and for spin-state alteration during close flybys.

Genealogy and stability of periodic orbit families around uniformly rotating asteroids

NASA Astrophysics Data System (ADS)

Hou, Xiyun; Xin, Xiaosheng; Feng, Jinglang

2018-03-01

Resonance orbits around a uniformly rotating asteroid are studied from the approach of periodic orbits in this work. Three periodic families (denoted as I, II, and III in the paper) are fundamental in organizing the resonance families. For the planar case: (1) Genealogy and stability of Families I, II and the prograde resonance families are studied. For extremely irregular asteroids, family genealogy close to the asteroid is greatly distorted from that of the two body-problem (2BP), indicating that it is inappropriate to treat the orbital motions as perturbed Keplerian orbits. (2) Genealogy and stability of Family III are also studied. Stability of this family may be destroyed by the secular resonance between the orbital ascending node's precession and the asteroid's rotation. For the spatial case: (1) Genealogy of the near circular three-dimensional periodic families are studied. The genealogy may be broken apart by families of eccentric frozen orbits whose argument of perigee is ;frozen; in space. (2) The joint effects between the secular resonance and the orbital resonances may cause instability to three-dimensional orbital motion with orbit inclinations close to the critical values. Applying the general methodology to a case study - the asteroid Eros and also considering higher order non-spherical terms, some extraordinary orbits are found, such as the ones with orbital plane co-rotating with the asteroid, and the stable frozen orbits with argument of perigee librating around values different from 0°, 90°, 180°, 270°.

The different ways to obtain digital images of urine microscopy findings: Their advantages and limitations.

PubMed

Fogazzi, G B; Garigali, G

2017-03-01

We describe three ways to take digital images of urine sediment findings. Way 1 encompasses a digital camera permanently mounted on the microscope and connected with a computer equipped with a proprietary software to acquire, process and store the images. Way 2 is based on the use of inexpensive compact digital cameras, held by hands - or mounted on a tripod - close to one eyepiece of the microscope. Way 3 is based on the use of smartphones, held by hands close to one eyepiece of the microscope or connected to the microscope by an adapter. The procedures, advantages and limitations of each way are reported. Copyright © 2017. Published by Elsevier B.V.

The distribution of ion orbit loss fluxes of ions and energy from the plasma edge across the last closed flux surface into the scrape-off layer

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

Stacey, Weston M.; Schumann, Matthew T.

A more detailed calculation strategy for the evaluation of ion orbit loss of thermalized plasma ions in the edge of tokamaks is presented. In both this and previous papers, the direct loss of particles from internal flux surfaces is calculated from the conservation of canonical angular momentum, energy, and magnetic moment. The previous result that almost all of the ion energy and particle fluxes crossing the last closed flux surface are in the form of ion orbit fluxes is confirmed, and the new result that the distributions of these fluxes crossing the last closed flux surface into the scrape-off layermore » are very strongly peaked about the outboard midplane is demonstrated. Previous results of a preferential loss of counter current particles leading to a co-current intrinsic rotation peaking just inside of the last closed flux surface are confirmed. Various physical details are discussed.« less

The location of Airy-0, the Mars prime meridian reference, from stereo photogrammetric processing of THEMIS IR imaging and digital elevation data

NASA Astrophysics Data System (ADS)

Duxbury, T. C.; Christensen, P.; Smith, D. E.; Neumann, G. A.; Kirk, R. L.; Caplinger, M. A.; Albee, A. A.; Seregina, N. V.; Neukum, G.; Archinal, B. A.

2014-12-01

The small crater Airy-0 was selected from Mariner 9 images to be the reference for the Mars prime meridian. Initial analyses in the year 2000 tied Viking Orbiter and Mars Orbiter Camera images of Airy-0 to the evolving Mars Orbiter Laser Altimeter global digital terrain model to update the location of Airy-0. Based upon this tie and radiometric tracking of landers/rovers from Earth, new expressions for the Mars spin axis direction, spin rate, and prime meridian epoch value were produced to define the orientation of the Martian surface in inertial space over time. Since the Mars Global Surveyor mission and Mars Orbiter Laser Altimeter global digital terrain model were completed some time ago, a more exhaustive study has been performed to determine the accuracy of the Airy-0 location and orientation of Mars at the standard epoch. Thermal Emission Imaging System (THEMIS) IR image cubes of the Airy and Gale crater regions were tied to the global terrain grid using precision stereo photogrammetric image processing techniques. The Airy-0 location was determined to be about 0.001° east of its predicted location using the currently defined International Astronomical Union (IAU) prime meridian location. Information on this new location and how it was derived will be provided to the NASA Mars Exploration Program Geodesy and Cartography Working Group for their assessment. This NASA group will make a recommendation to the IAU Working Group on Cartographic Coordinates and Rotational Elements to update the expression for the Mars spin axis direction, spin rate, and prime meridian location.

The GEOS-3 orbit determination investigation

NASA Technical Reports Server (NTRS)

Pisacane, V. L.; Eisner, A.; Yionoulis, S. M.; Mcconahy, R. J.; Black, H. D.; Pryor, L. L.

1978-01-01

The nature and improvement in satellite orbit determination when precise altimetric height data are used in combination with conventional tracking data was determined. A digital orbit determination program was developed that could singly or jointly use laser ranging, C-band ranging, Doppler range difference, and altimetric height data. Two intervals were selected and used in a preliminary evaluation of the altimeter data. With the data available, it was possible to determine the semimajor axis and eccentricity to within several kilometers, in addition to determining an altimeter height bias. When used jointly with a limited amount of either C-band or laser range data, it was shown that altimeter data can improve the orbit solution.

Effects of Digitization and JPEG Compression on Land Cover Classification Using Astronaut-Acquired Orbital Photographs

NASA Technical Reports Server (NTRS)

Robinson, Julie A.; Webb, Edward L.; Evangelista, Arlene

2000-01-01

Studies that utilize astronaut-acquired orbital photographs for visual or digital classification require high-quality data to ensure accuracy. The majority of images available must be digitized from film and electronically transferred to scientific users. This study examined the effect of scanning spatial resolution (1200, 2400 pixels per inch [21.2 and 10.6 microns/pixel]), scanning density range option (Auto, Full) and compression ratio (non-lossy [TIFF], and lossy JPEG 10:1, 46:1, 83:1) on digital classification results of an orbital photograph from the NASA - Johnson Space Center archive. Qualitative results suggested that 1200 ppi was acceptable for visual interpretive uses for major land cover types. Moreover, Auto scanning density range was superior to Full density range. Quantitative assessment of the processing steps indicated that, while 2400 ppi scanning spatial resolution resulted in more classified polygons as well as a substantially greater proportion of polygons < 0.2 ha, overall agreement between 1200 ppi and 2400 ppi was quite high. JPEG compression up to approximately 46:1 also did not appear to have a major impact on quantitative classification characteristics. We conclude that both 1200 and 2400 ppi scanning resolutions are acceptable options for this level of land cover classification, as well as a compression ratio at or below approximately 46:1. Auto range density should always be used during scanning because it acquires more of the information from the film. The particular combination of scanning spatial resolution and compression level will require a case-by-case decision and will depend upon memory capabilities, analytical objectives and the spatial properties of the objects in the image.

RESONANCES REQUIRED: DYNAMICAL ANALYSIS OF THE 24 Sex AND HD 200964 PLANETARY SYSTEMS

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

Wittenmyer, Robert A.; Horner, Jonathan; Tinney, C. G., E-mail: rob@phys.unsw.edu.au

We perform several suites of highly detailed dynamical simulations to investigate the architectures of the 24 Sextantis and HD 200964 planetary systems. The best-fit orbital solution for the two planets in the 24 Sex system places them on orbits with periods that lie very close to 2:1 commensurability, while that for the HD 200964 system places the two planets therein in orbits whose periods lie close to a 4:3 commensurability. In both cases, the proposed best-fit orbits are mutually crossing-a scenario that is only dynamically feasible if the planets are protected from close encounters by the effects of mutual mean-motionmore » resonance (MMR). Our simulations reveal that the best-fit orbits for both systems lie within narrow islands of dynamical stability, and are surrounded by much larger regions of extreme instability. As such, we show that the planets are only feasible if they are currently trapped in mutual MMR-the 2:1 resonance in the case of 24 Sex b and c, and the 4:3 resonance in the case of HD 200964 b and c. In both cases, the region of stability is strongest and most pronounced when the planetary orbits are mutually coplanar. As the inclination of planet c with respect to planet b is increased, the stability of both systems rapidly collapses.« less

Pioneer Venus Orbiter planar retarding potential analyzer plasma experiment

NASA Technical Reports Server (NTRS)

Knudsen, W. C.; Bakke, J.; Spenner, K.; Novak, V.

1980-01-01

The retarding potential analyzer (RPA) on the Pioneer Venus Orbiter Mission measures most of the thermal plasma parameters within and near the Venusian ionosphere. Parameters include total ion concentration, concentrations of the more abundant ions, ion temperatures, ion drift velocity, electron temperature, and low-energy (0-50 eV) electron distribution function. Several functions not previously used in RPA's were developed and incorporated into this instrument to accomplish these measurements on a spinning spacecraft with a small bit rate. The more significant functions include automatic electrometer ranging with background current compensation; digital, quadratic retarding potential step generation for the ion and low-energy electron scans; a current sampling interval of 2 ms throughout all scans; digital logic inflection point detection and data selection; and automatic ram direction detection.

Image matching for digital close-range stereo photogrammetry based on constraints of Delaunay triangulated network and epipolar-line

NASA Astrophysics Data System (ADS)

Zhang, K.; Sheng, Y. H.; Li, Y. Q.; Han, B.; Liang, Ch.; Sha, W.

2006-10-01

In the field of digital photogrammetry and computer vision, the determination of conjugate points in a stereo image pair, referred to as "image matching," is the critical step to realize automatic surveying and recognition. Traditional matching methods encounter some problems in the digital close-range stereo photogrammetry, because the change of gray-scale or texture is not obvious in the close-range stereo images. The main shortcoming of traditional matching methods is that geometric information of matching points is not fully used, which will lead to wrong matching results in regions with poor texture. To fully use the geometry and gray-scale information, a new stereo image matching algorithm is proposed in this paper considering the characteristics of digital close-range photogrammetry. Compared with the traditional matching method, the new algorithm has three improvements on image matching. Firstly, shape factor, fuzzy maths and gray-scale projection are introduced into the design of synthetical matching measure. Secondly, the topology connecting relations of matching points in Delaunay triangulated network and epipolar-line are used to decide matching order and narrow the searching scope of conjugate point of the matching point. Lastly, the theory of parameter adjustment with constraint is introduced into least square image matching to carry out subpixel level matching under epipolar-line constraint. The new algorithm is applied to actual stereo images of a building taken by digital close-range photogrammetric system. The experimental result shows that the algorithm has a higher matching speed and matching accuracy than pyramid image matching algorithm based on gray-scale correlation.

Close up view of the center console on the flight ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Close up view of the center console on the flight deck of the Orbiter Discovery showing the console's instrumentation and controls. The commanders station is located to the left in this view and the pilot's station is to the right in the view. The handle and lever located on the right side of the center console and towards its front is one of a pair, the commander has one on the left of his seat in his station, of Speed Brake/Thrust Controllers. These are dual purpose controllers. During ascent the controller can be use to throttle the main engines and during entry the controllers can be used to control aerodynamic drag by opening or closing the orbiter's speed brake. - Space Transportation System, Orbiter Discovery (OV-103), Lyndon B. Johnson Space Center, 2101 NASA Parkway, Houston, Harris County, TX

Quantifying Forest Ground Flora Biomass Using Close-range Remote Sensing

Treesearch

Paul F. Doruska; Robert C. Weih; Matthew D. Lane; Don C. Bragg

2005-01-01

Close-range remote sensing was used to estimate biomass of forest ground flora in Arkansas. Digital images of a series of 1-m² plots were taken using Kodak DCS760 and Kodak DCS420CIR digital cameras. ESRI ArcGIS™ and ERDAS Imagine® software was used to calculate the Normalized Difference Vegetation Index (NDVI) and the Average Visible...

Digital compensation techniques for the effects of time lag in closed-loop simulation using the 6 DOF motion system

NASA Technical Reports Server (NTRS)

Brown, R.

1982-01-01

Efforts are continued to develop digital filter compensation schemes for the correction of momentum gains observed in the closed loop simulation of the docking of two satellites using the 6 DOF motion system. Several filters that work well for small delays ( .100ms) and a non-preloaded probe are discussed.

Topographic map of the Coronae Montes region of Mars - MTM 500k -35/087E OMKTT

USGS Publications Warehouse

Rosiek, Mark R.; Redding, Bonnie L.; Galuszca, Donna M.

2005-01-01

This map is part of a series of topographic maps of areas of special scientific interest on Mars. The topography was compiled photogrammetrically using Viking Orbiter stereo image pairs. The contour interval is 250 m. Horizontal and vertical control was established using the USGS Mars Digital Image Model 2.0 (MDIM 2.0) and data from the Mars Orbiter Laser Altimeter (MOLA).

KSC-00pp1416

NASA Image and Video Library

2000-09-08

KENNEDY SPACE CENTER, FLA. -- This view of the shock wave condensation collars backlit by the sun occurred during the launch of Atlantis on STS-106 and was captured on an engineering 35mm motion picture film. One frame was digitized to make this still image. Although the primary effect is created by the Orbiter forward fuselage, secondary effects can be seen on the SRB forward skirt, Orbiter vertical stabilizer and wing trailing edges (behind SSME's).

KSC00pp1416

NASA Image and Video Library

2000-09-08

KENNEDY SPACE CENTER, FLA. -- This view of the shock wave condensation collars backlit by the sun occurred during the launch of Atlantis on STS-106 and was captured on an engineering 35mm motion picture film. One frame was digitized to make this still image. Although the primary effect is created by the Orbiter forward fuselage, secondary effects can be seen on the SRB forward skirt, Orbiter vertical stabilizer and wing trailing edges (behind SSME's).

Topographic Map of the Northeast Ascraeus Mons Region of Mars - MTM 500k 15/257E OMKT

USGS Publications Warehouse

,

2004-01-01

This map is part of a series of topographic maps of areas of special scientific interest on Mars. The topography was compiled photogrammetically using Viking Orbiter stereo image pairs. The contour interval is 250 meters. Horizontal and vertical control was established using the USGS Mars Digital Image Model 2.0 (MDIM 2.0) and data from the Mars Orbiter Laser Altimeter (MOLA).

Topographic Map of the Northwest Ascraeus Mons Region of Mars - MTM 500k 15/252E OMKT

USGS Publications Warehouse

,

2004-01-01

This map is part of a series of topographic maps of areas of special scientific interest on Mars. The topography was compiled photogrammetically using Viking Orbiter stereo image pairs. The contour interval is 250 meters. Horizontal and vertical control was established using the USGS Mars Digital Image Model 2.0 (MDIM 2.0) and data from the Mars Orbiter Laser Altimeter (MOLA).

Topographic Map of the Southeast Ascraeus Mons Region of Mars - MTM 500k 10/257E OMKT

USGS Publications Warehouse

,

2004-01-01

This map is part of a series of topographic maps of areas of special scientific interest on Mars. The topography was compiled photogrammetically using Viking Orbiter stereo image pairs. The contour interval is 250 meters. Horizontal and vertical control was established using the USGS Mars Digital Image Model 2.0 (MDIM 2.0) and data from the Mars Orbiter Laser Altimeter (MOLA).

Topographic Map of the Southwest Ascraeus Mons Region of Mars - MTM 500k 10/252E OMKT

USGS Publications Warehouse

,

2004-01-01

This map is part of a series of topographic maps of areas of special scientific interest on Mars. The topography was compiled photogrammetically using Viking Orbiter stereo image pairs. The contour interval is 250 meters. Horizontal and vertical control was established using the USGS Mars Digital Image Model 2.0 (MDIM 2.0) and data from the Mars Orbiter Laser Altimeter (MOLA).

A New Lunar Digital Elevation Model from the Lunar Orbiter Laser Altimeter and SELENE Terrain Camera

NASA Technical Reports Server (NTRS)

Barker, M. K.; Mazarico, E.; Neumann, G. A.; Zuber, M. T.; Haruyama, J.; Smith, D. E.

2015-01-01

We present an improved lunar digital elevation model (DEM) covering latitudes within +/-60 deg, at a horizontal resolution of 512 pixels per degree ( approx.60 m at the equator) and a typical vertical accuracy approx.3 to 4 m. This DEM is constructed from approx.4.5 ×10(exp 9) geodetically-accurate topographic heights from the Lunar Orbiter Laser Altimeter (LOLA) onboard the Lunar Reconnaissance Orbiter, to which we co-registered 43,200 stereo-derived DEMs (each 1 deg×1 deg) from the SELENE Terrain Camera (TC) ( approx.10(exp 10) pixels total). After co-registration, approximately 90% of the TC DEMs show root-mean-square vertical residuals with the LOLA data of < 5 m compared to approx.50% prior to co-registration. We use the co-registered TC data to estimate and correct orbital and pointing geolocation errors from the LOLA altimetric profiles (typically amounting to < 10 m horizontally and < 1 m vertically). By combining both co-registered datasets, we obtain a near-global DEM with high geodetic accuracy, and without the need for surface interpolation. We evaluate the resulting LOLA + TC merged DEM (designated as "SLDEM2015") with particular attention to quantifying seams and crossover errors.

Homoclinic orbits and critical points of barrier functions

NASA Astrophysics Data System (ADS)

Cannarsa, Piermarco; Cheng, Wei

2015-06-01

We interpret the close link between the critical points of Mather's barrier functions and minimal homoclinic orbits with respect to the Aubry sets on {{T}}n . We also prove a critical point theorem for barrier functions and the existence of such homoclinic orbits on {{T}}2 as an application.

Space shuttle pilot-induced-oscillation research testing

NASA Technical Reports Server (NTRS)

Powers, B. G.

1984-01-01

The simulation requirements for investigation of pilot-induced-oscillation (PIO) characteristics during the landing phase are discussed. Orbiters simulations and F-8 digital fly-by-wire aircraft tests are addressed.

Autonomous orbital navigation using Kepler's equation

NASA Technical Reports Server (NTRS)

Boltz, F. W.

1974-01-01

A simple method of determining the six elements of elliptic satellite orbits has been developed for use aboard manned and unmanned spacecraft orbiting the earth, moon, or any planet. The system requires the use of a horizon sensor or other device for determining the local vertical, a precision clock or timing device, and Apollo-type navigation equipment including an inertial measurement unit (IMU), a digital computer, and a coupling data unit. The three elements defining the in-plane motion are obtained from simultaneous measurements of central angle traversed around the planet and elapsed flight time using a linearization of Kepler's equation about a reference orbit. It is shown how Kalman filter theory may also be used to determine the in-plane orbital elements. The three elements defining the orbit orientation are obtained from position angles in celestial coordinates derived from the IMU with the spacecraft vertically oriented after alignment of the IMU to a known inertial coordinate frame.

Closeup view of the Reinforced CarbonCarbon nose cap on the ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Close-up view of the Reinforced Carbon-Carbon nose cap on the front fuselage of the Orbiter Discovery. Note the 76-wheeled orbiter transfer system attached to the orbiter at the forward attach point, the same attach point used to mount the orbiter onto the External Tank. This view was taken at Kennedy Space Center. - Space Transportation System, Orbiter Discovery (OV-103), Lyndon B. Johnson Space Center, 2101 NASA Parkway, Houston, Harris County, TX

Digital Astronaut Photography: A Discovery Dataset for Archaeology

NASA Technical Reports Server (NTRS)

Stefanov, William L.

2010-01-01

Astronaut photography acquired from the International Space Station (ISS) using commercial off-the-shelf cameras offers a freely-accessible source for high to very high resolution (4-20 m/pixel) visible-wavelength digital data of Earth. Since ISS Expedition 1 in 2000, over 373,000 images of the Earth-Moon system (including land surface, ocean, atmospheric, and lunar images) have been added to the Gateway to Astronaut Photography of Earth online database (http://eol.jsc.nasa.gov ). Handheld astronaut photographs vary in look angle, time of acquisition, solar illumination, and spatial resolution. These attributes of digital astronaut photography result from a unique combination of ISS orbital dynamics, mission operations, camera systems, and the individual skills of the astronaut. The variable nature of astronaut photography makes the dataset uniquely useful for archaeological applications in comparison with more traditional nadir-viewing multispectral datasets acquired from unmanned orbital platforms. For example, surface features such as trenches, walls, ruins, urban patterns, and vegetation clearing and regrowth patterns may be accentuated by low sun angles and oblique viewing conditions (Fig. 1). High spatial resolution digital astronaut photographs can also be used with sophisticated land cover classification and spatial analysis approaches like Object Based Image Analysis, increasing the potential for use in archaeological characterization of landscapes and specific sites.

ASPS performance with large payloads onboard the Shuttle Orbiter. [Annular Suspension and Pointing System

NASA Technical Reports Server (NTRS)

Keckler, C. R.

1980-01-01

A high fidelity digital computer simulation was used to establish the viability of the Annular Suspension and Pointing System (ASPS) for satisfying the pointing and stability requirements of facility class payloads, such as the Solar Optical Telescope, when subjected to the Orbiter disturbance environment. The ASPS and its payload were subjected to disturbances resulting from crew motions in the Orbiter aft flight deck and VRCS thruster firings. Worst case pointing errors of 0.005 arc seconds were experienced under the disturbance environment simulated; this is well within the 0.08 arc seconds requirement specified by the payload.

Analysis of closed orbit deviations for a first direct deuteron electric dipole moment measurement at the cooler synchrotron COSY

NASA Astrophysics Data System (ADS)

Schmidt, V.; Lehrach, A.

2017-07-01

The Jülich Electric Dipole moment Investigations (JEDI) collaboration in Julich is preparing a direct EDM measurement of protons and deuterons first at the storage ring COSY (COoler SYnchrotron) and later at a dedicated storage ring. Ensuring a precise measurement, various beam and spin manipulating effects have to be considered and investigated. A distortion of the closed orbit is one of the major sources for systematic uncertainties. Therefore misalignments of magnets and residual power supply oscillations are simulated using the MAD-X code in order to analyse their effect on the orbit. The underlying model for all simulations includes the dipoles, quadrupoles and sextupoles at COSY as well as the corrector magnets and BPMs (Beam Position Monitors). Since most sextupoles are only used during beam extraction, the sextupole strengths are set to zero resulting in a linear machine. The optics is adjusted in a way that the dispersion is zero in the straight sections. The closed orbit studies are performed for deuterons with a momentum of 970 MeV/c.

Binary Star Orbits. V. The Nearby White Dwarf/Red Dwarf Pair 40 Eri BC

NASA Astrophysics Data System (ADS)

Mason, Brian D.; Hartkopf, William I.; Miles, Korie N.

2017-11-01

A new relative orbit solution with new dynamical masses is determined for the nearby white dwarf-red dwarf pair 40 Eri BC. The period is 230.09 ± 0.68 years. It is predicted to close slowly over the next half-century, getting as close as 1.″32 in early 2066. We determine masses of 0.575 ± 0.018 {{ M }}⊙ for the white dwarf and 0.2041 ± 0.0064 {{ M }}⊙ for the red dwarf companion. The inconsistency of the masses determined by gravitational redshift and dynamical techniques, due to a premature orbit calculation, no longer exists.

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

Araujo, R. A. N.; Sfair, R.; Winter, O. C., E-mail: ran.araujo@gmail.com, E-mail: rsfair@feg.unesp.br, E-mail: ocwinter@gmail.com

The Centaur population is composed of minor bodies wandering between the giant planets that frequently perform close gravitational encounters with these planets, leading to a chaotic orbital evolution. Recently, the discovery of two well-defined narrow rings was announced around the Centaur 10199 Chariklo. The rings are assumed to be in the equatorial plane of Chariklo and to have circular orbits. The existence of a well-defined system of rings around a body in such a perturbed orbital region poses an interesting new problem. Are the rings of Chariklo stable when perturbed by close gravitational encounters with the giant planets? Our approachmore » to address this question consisted of forward and backward numerical simulations of 729 clones of Chariklo, with similar initial orbits, for a period of 100 Myr. We found, on average, that each clone experiences during its lifetime more than 150 close encounters with the giant planets within one Hill radius of the planet in question. We identified some extreme close encounters that were able to significantly disrupt or disturb the rings of Chariklo. About 3% of the clones lose their rings and about 4% of the clones have their rings significantly disturbed. Therefore, our results show that in most cases (more than 90%), the close encounters with the giant planets do not affect the stability of the rings in Chariklo-like systems. Thus, if there is an efficient mechanism that creates the rings, then these structures may be common among these kinds of Centaurs.« less

Excitations and relaxation dynamics in multiferroic GeV4S8 studied by terahertz and dielectric spectroscopy

NASA Astrophysics Data System (ADS)

Reschke, S.; Wang, Zhe; Mayr, F.; Ruff, E.; Lunkenheimer, P.; Tsurkan, V.; Loidl, A.

2017-10-01

We report on THz time-domain spectroscopy on multiferroic GeV4S8 , which undergoes orbital ordering at a Jahn-Teller transition at 30.5 K and exhibits antiferromagnetic order below 14.6 K. The THz experiments are complemented by dielectric experiments at audio and radio frequencies. We identify a low-lying excitation close to 0.5 THz, which is only weakly temperature dependent and probably corresponds to a molecular excitation within the electronic level scheme of the V4 clusters. In addition, we detect complex temperature-dependent behavior of a low-lying phononic excitation, closely linked to the onset of orbitally driven ferroelectricity. In the high-temperature cubic phase, which is paramagnetic and orbitally disordered, this excitation is of relaxational character becomes an overdamped Lorentzian mode in the orbitally ordered phase below the Jahn-Teller transition, and finally appears as well-defined phonon excitation in the antiferromagnetic state. Abrupt changes in the real and imaginary parts of the complex dielectric permittivity show that orbital ordering appears via a structural phase transition with strong first-order character and that the onset of antiferromagnetic order is accompanied by significant structural changes, which are of first-order character, too. Dielectric spectroscopy documents that at low frequencies, significant dipolar relaxations are present in the orbitally ordered, paramagnetic phase only. In contrast to the closely related GaV4S8 , this relaxation dynamics that most likely mirrors coupled orbital and polar fluctuations does not seem to be related to the dynamic processes detected in the THz regime.

Orbital stability close to asteroid 624 Hektor using the polyhedral model

NASA Astrophysics Data System (ADS)

Jiang, Yu; Baoyin, Hexi; Li, Hengnian

2018-03-01

We investigate the orbital stability close to the unique L4-point Jupiter binary Trojan asteroid 624 Hektor. The gravitational potential of 624 Hektor is calculated using the polyhedron model with observational data of 2038 faces and 1021 vertexes. Previous studies have presented three different density values for 624 Hektor. The equilibrium points in the gravitational potential of 624 Hektor with different density values have been studied in detail. There are five equilibrium points in the gravitational potential of 624 Hektor no matter the density value. The positions, Jacobian, eigenvalues, topological cases, stability, as well as the Hessian matrix of the equilibrium points are investigated. For the three different density values the number, topological cases, and the stability of the equilibrium points with different density values are the same. However, the positions of the equilibrium points vary with the density value of the asteroid 624 Hektor. The outer equilibrium points move away from the asteroid's mass center when the density increases, and the inner equilibrium point moves close to the asteroid's mass center when the density increases. There exist unstable periodic orbits near the surface of 624 Hektor. We calculated an orbit near the primary's equatorial plane of this binary Trojan asteroid; the results indicate that the orbit remains stable after 28.8375 d.

Galileo Jupiter approach orbit determination

NASA Technical Reports Server (NTRS)

Miller, J. K.; Nicholson, F. T.

1984-01-01

Orbit determination characteristics of the Jupiter approach phase of the Galileo mission are described. Predicted orbit determination performance is given for the various mission events that occur during Jupiter approach. These mission events include delivery of an atmospheric entry probe, acquisition of probe science data by the Galileo orbiter for relay to earth, delivery of an orbiter to a close encounter of the Galilean satellite Io, and insertion of the orbiter into orbit about Jupiter. The orbit determination strategy and resulting accuracies are discussed for the data types which include Doppler, range, optical imaging of Io, and a new Very Long Baseline Interferometry (VLBI) data type called Differential One-Way Range (DOR).

Behind Closed Doors: The Pedagogy and Interventionist Practice of Digital Storytelling

ERIC Educational Resources Information Center

Eisenhauer, Jennifer

2012-01-01

Through arts-based research and digital storytelling, the author investigates the representation of psychiatric disabilities in this article and proposes that digital storytelling can be an interventionist artistic and pedagogical process through which to challenge dominant stigmatizing representations of psychiatric disability.

Low Earth orbit communications satellite

NASA Technical Reports Server (NTRS)

Moroney, D.; Lashbrook, D.; Mckibben, B.; Gardener, N.; Rivers, T.; Nottingham, G.; Golden, B.; Barfield, B.; Bruening, J.; Wood, D.

1992-01-01

A current thrust in satellite communication systems considers a low-Earth orbiting constellations of satellites for continuous global coverage. Conceptual design studies have been done at the time of this design project by LORAL Aerospace Corporation under the program name GLOBALSTAR and by Motorola under their IRIDIUM program. This design project concentrates on the spacecraft design of the GLOBALSTAR low-Earth orbiting communication system. Overview information on the program was gained through the Federal Communications Commission licensing request. The GLOBALSTAR system consists of 48 operational satellites positioned in a Walker Delta pattern providing global coverage and redundancy. The operational orbit is 1389 km (750 nmi) altitude with eight planes of six satellites each. The orbital planes are spaced 45 deg., and the spacecraft are separated by 60 deg. within the plane. A Delta 2 launch vehicle is used to carry six spacecraft for orbit establishment. Once in orbit, the spacecraft will utilize code-division multiple access (spread spectrum modulation) for digital relay, voice, and radio determination satellite services (RDSS) yielding position determination with accuracy up to 200 meters.

Search for and Study of Nearly Periodic Orbits in the Plane Problem of Three Equal-Mass Bodies

NASA Astrophysics Data System (ADS)

Martynova, A. I.; Orlov, V. V.

2005-09-01

We analyze nearly periodic solutions in the plane problem of three equal-mass bodies by numerically simulating the dynamics of triple systems. We identify families of orbits in which all three points are on one straight line (syzygy) at the initial time. In this case, at fixed total energy of a triple system, the set of initial conditions is a bounded region in four-dimensional parameter space. We scan this region and identify sets of trajectories in which the coordinates and velocities of all bodies are close to their initial values at certain times (which are approximately multiples of the period). We classify the nearly periodic orbits by the structure of trajectory loops over one period. We have found the families of orbits generated by von Schubart’s stable periodic orbit revealed in the rectilinear three-body problem. We have also found families of hierarchical, nearly periodic trajectories with prograde and retrograde motions. In the orbits with prograde motions, the trajectory loops of two close bodies form looplike structures. The trajectories with retrograde motions are characterized by leafed structures. Orbits with central and axial symmetries are identified among the families found.

Transiting circumbinary planets Kepler-34 b and Kepler-35 b.

PubMed

Welsh, William F; Orosz, Jerome A; Carter, Joshua A; Fabrycky, Daniel C; Ford, Eric B; Lissauer, Jack J; Prša, Andrej; Quinn, Samuel N; Ragozzine, Darin; Short, Donald R; Torres, Guillermo; Winn, Joshua N; Doyle, Laurance R; Barclay, Thomas; Batalha, Natalie; Bloemen, Steven; Brugamyer, Erik; Buchhave, Lars A; Caldwell, Caroline; Caldwell, Douglas A; Christiansen, Jessie L; Ciardi, David R; Cochran, William D; Endl, Michael; Fortney, Jonathan J; Gautier, Thomas N; Gilliland, Ronald L; Haas, Michael R; Hall, Jennifer R; Holman, Matthew J; Howard, Andrew W; Howell, Steve B; Isaacson, Howard; Jenkins, Jon M; Klaus, Todd C; Latham, David W; Li, Jie; Marcy, Geoffrey W; Mazeh, Tsevi; Quintana, Elisa V; Robertson, Paul; Shporer, Avi; Steffen, Jason H; Windmiller, Gur; Koch, David G; Borucki, William J

2012-01-11

Most Sun-like stars in the Galaxy reside in gravitationally bound pairs of stars (binaries). Although long anticipated, the existence of a 'circumbinary planet' orbiting such a pair of normal stars was not definitively established until the discovery of the planet transiting (that is, passing in front of) Kepler-16. Questions remained, however, about the prevalence of circumbinary planets and their range of orbital and physical properties. Here we report two additional transiting circumbinary planets: Kepler-34 (AB)b and Kepler-35 (AB)b, referred to here as Kepler-34 b and Kepler-35 b, respectively. Each is a low-density gas-giant planet on an orbit closely aligned with that of its parent stars. Kepler-34 b orbits two Sun-like stars every 289 days, whereas Kepler-35 b orbits a pair of smaller stars (89% and 81% of the Sun's mass) every 131 days. The planets experience large multi-periodic variations in incident stellar radiation arising from the orbital motion of the stars. The observed rate of circumbinary planets in our sample implies that more than ∼1% of close binary stars have giant planets in nearly coplanar orbits, yielding a Galactic population of at least several million.

The magnetic field in the very close neighborhood of Mars according to data from the Mars 2 and Mars 3 spacecraft

NASA Technical Reports Server (NTRS)

Dolginov, S. S.; Yeroshenko, Y. G.; Zhuzgov, L. N.

1972-01-01

The magnetic field in the close proximity of planet Mars according to data from Mars 2 and Mars 3 spacecraft is discussed. The magnetometers on the spacecraft detected a field whose intensity near the orbital periapses was 7 to 10 times higher than the interplanetary field at the distance of the Martian orbit. The nature of the observed field is described.

Hypervelocity stars from young stellar clusters in the Galactic Centre

NASA Astrophysics Data System (ADS)

Fragione, G.; Capuzzo-Dolcetta, R.; Kroupa, P.

2017-05-01

The enormous velocities of the so-called hypervelocity stars (HVSs) derive, likely, from close interactions with massive black holes, binary stars encounters or supernova explosions. In this paper, we investigate the origin of HVSs as consequence of the close interaction between the Milky Way central massive black hole and a passing-by young stellar cluster. We found that both single and binary HVSs may be generated in a burst-like event, as the cluster passes near the orbital pericentre. High-velocity stars will move close to the initial cluster orbital plane and in the direction of the cluster orbital motion at the pericentre. The binary fraction of these HVS jets depends on the primordial binary fraction in the young cluster. The level of initial mass segregation determines the value of the average mass of the ejected stars. Some binary stars will merge, continuing their travel across and out of the Galaxy as blue stragglers.

Orbital Disturbance Analysis due to the Lunar Gravitational Potential and Deviation Minimization through the Trajectory Control in Closed Loop

NASA Astrophysics Data System (ADS)

Gonçalves, L. D.; Rocco, E. M.; de Moraes, R. V.

2013-10-01

A study evaluating the influence due to the lunar gravitational potential, modeled by spherical harmonics, on the gravity acceleration is accomplished according to the model presented in Konopliv (2001). This model provides the components x, y and z for the gravity acceleration at each moment of time along the artificial satellite orbit and it enables to consider the spherical harmonic degree and order up to100. Through a comparison between the gravity acceleration from a central field and the gravity acceleration provided by Konopliv's model, it is obtained the disturbing velocity increment applied to the vehicle. Then, through the inverse problem, the Keplerian elements of perturbed orbit of the satellite are calculated allowing the orbital motion analysis. Transfer maneuvers and orbital correction of lunar satellites are simulated considering the disturbance due to non-uniform gravitational potential of the Moon, utilizing continuous thrust and trajectory control in closed loop. The simulations are performed using the Spacecraft Trajectory Simulator-STRS, Rocco (2008), which evaluate the behavior of the orbital elements, fuel consumption and thrust applied to the satellite over the time.

KSC-04pd1599

NASA Image and Video Library

2004-07-14

KENNEDY SPACE CENTER, FLA. - At Vandenberg Air Force Base in California, Orbital Sciences technicians watch closely as the DART (Demonstration for Autonomous Rendezvous Technology) flight demonstrator is lowered onto a stand. The spacecraft was developed to prove technologies for locating and maneuvering near an orbiting satellite. Future applications of technologies developed by the DART project will benefit the nation in future space-vehicle systems development requiring in-space assembly, services or other autonomous rendezvous operations. Designed and developed for NASA by Orbital Sciences Corporation in Dulles, Va., the DART spacecraft will be launched on a Pegasus launch vehicle. At about 40,000 feet over the Pacific Ocean, the Pegasus will be released from Orbital’s Stargazer L-1011 aircraft, fire its rocket motors and boost DART into a polar orbit approximately 472 miles by 479 miles. Once in orbit, DART will rendezvous with a target satellite, the Multiple Paths, Beyond-Line-of-Site Communications satellite, also built by Orbital Sciences. DART will then perform several close proximity operations, such as moving toward and away from the satellite using navigation data provided by onboard sensors. DART is scheduled for launch no earlier than Oct. 18.

Electrical crosstalk-coupling measurement and analysis for digital closed loop fibre optic gyro

NASA Astrophysics Data System (ADS)

Jin, Jing; Tian, Hai-Ting; Pan, Xiong; Song, Ning-Fang

2010-03-01

The phase modulation and the closed-loop controller can generate electrical crosstalk-coupling in digital closed-loop fibre optic gyro. Four electrical cross-coupling paths are verified by the open-loop testing approach. It is found the variation of ramp amplitude will lead to the alternation of gyro bias. The amplitude and the phase parameters of the electrical crosstalk signal are measured by lock-in amplifier, and the variation of gyro bias is confirmed to be caused by the alternation of phase according to the amplitude of the ramp. A digital closed-loop fibre optic gyro electrical crosstalk-coupling model is built by approximating the electrical cross-coupling paths as a proportion and integration segment. The results of simulation and experiment show that the modulation signal electrical crosstalk-coupling can cause the dead zone of the gyro when a small angular velocity is inputted, and it could also lead to a periodic vibration of the bias error of the gyro when a large angular velocity is inputted.

Automatic weld torch guidance control system

NASA Technical Reports Server (NTRS)

Smaith, H. E.; Wall, W. A.; Burns, M. R., Jr.

1982-01-01

A highly reliable, fully digital, closed circuit television optical, type automatic weld seam tracking control system was developed. This automatic tracking equipment is used to reduce weld tooling costs and increase overall automatic welding reliability. The system utilizes a charge injection device digital camera which as 60,512 inidividual pixels as the light sensing elements. Through conventional scanning means, each pixel in the focal plane is sequentially scanned, the light level signal digitized, and an 8-bit word transmitted to scratch pad memory. From memory, the microprocessor performs an analysis of the digital signal and computes the tracking error. Lastly, the corrective signal is transmitted to a cross seam actuator digital drive motor controller to complete the closed loop, feedback, tracking system. This weld seam tracking control system is capable of a tracking accuracy of + or - 0.2 mm, or better. As configured, the system is applicable to square butt, V-groove, and lap joint weldments.

Closeup view of the reinforced carboncarbon nose of the Orbiter ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Close-up view of the reinforced carbon-carbon nose of the Orbiter Discovery from the service platform in the Orbiter Processing Facility at Kennedy Space Center. Note the clear protective shield around the nose cap, and the reflective insulation protecting the Crew Compartment bulkhead and orbiter structure in the void created by the removal of the Forward Reaction Control Module. - Space Transportation System, Orbiter Discovery (OV-103), Lyndon B. Johnson Space Center, 2101 NASA Parkway, Houston, Harris County, TX

Closeup view of the aft fuselage of the Orbiter Discovery ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Close-up view of the aft fuselage of the Orbiter Discovery on the starboard side looking forward. This view is of the attach surface for the Orbiter Maneuvering System/Reaction Control System (OMS/RCS) Pod. The OMS/RCS pods are removed for processing and reconditioning at another facility. This view was taken from a service platform in the Orbiter Processing Facility at Kennedy Space Center. - Space Transportation System, Orbiter Discovery (OV-103), Lyndon B. Johnson Space Center, 2101 NASA Parkway, Houston, Harris County, TX

STS-1 landing at Edwards - first orbital mission

NASA Technical Reports Server (NTRS)

1981-01-01

The first flight of a space shuttle into space and back occurred from April 12 to April 14, 1981. After years of testing of the space shuttle Columbia and training the astronauts in simulators, the orbiter lifted off into space on the 12th, boosted by the seven million pounds of thrust supplied by its solid-propellant rockets and liquid-hydrogen engines. The flight, one of four Orbital Flight Tests of Columbia, served as a two-day demonstration of the first reusable, piloted spacecraft's ability to go into orbit and return safely to Earth. Columbia carried as its main payload a Developmental Flight Instrumentation pallet with instruments to record pressures, temperatures, and levels of acceleration at various points on the vehicle during launch, flight, and landing. One of many cameras aboard--a remote television camera--revealed some of the thermal protection tiles had disengaged during launch. As Columbia reentered the atmosphere from space at Mach 24 (24 times the speed of sound) after 36 orbits, aerodynamic heating built up to over 3,000 degrees Fahrenheit, causing some concern during the moments when ionized gases disrupted radio communication. But at 188,000 feet and Mach 10, mission commander John W. Young and pilot Robert L. Crippen reported that the orbiter was performing as expected. After a series of maneuvers to reduce speed, the mission commander and pilot prepared to land. In flight, Young and Crippen tested the spacecraft's on-board systems, fired the orbital maneuvering system for changing orbits, employed the reaction control system for controlling attitude, and opened and closed the payload doors. Columbia was the first reusable, piloted spacecraft, the first piloted lifting-reentry vehicle, and the first piloted spacecraft without a crew escape system. Energy management for the space shuttles was based on previous experience with the X-15 at NASA's Flight Research Center (which had become the Dryden Flight Research Center in 1976). Landing the shuttles without power--and therefore without the weight penalty of an additional engine and fuel--was based on previous experience at the Flight Research Center with piloted lifting bodies that also landed without power, as had the X-15s. Dryden and Edwards Air Force Base (AFB) had also hosted the approach and landing tests of the shuttle prototype Enterprise in 1977 and had tested the computers used for the shuttles' flight control systems in the F-8 Digital Fly-By-Wire aircraft, which also contributed to the solution of a dangerous pilot induced oscillation that occurred on the final approach and landing test. In this clip Young and Crippen fly the orbiter Columbia to a picture-perfect, unpowered landing on the dry lakebed runway 23 at Edwards AFB, CA, after it's first orbital flight, which ended on April 14.

Study to investigate and evaluate means of optimizing the Ku-band combined radar/communication functions for the space shuttle

NASA Technical Reports Server (NTRS)

Weber, C. L.; Alem, W. K.; Simon, M. K.

1977-01-01

The Ku band radar system on the shuttle orbiter operates in both a search and a tracking mode, and its transmitter and antennas share time with the communication mode in the integrated system. The power allocation properties and the Costa subloop subcarrier tracking performance associated with the baseline digital phase shift implementation of the three channel orbiter Ku band modulator are discussed.

Closeup view of the payload bay side of the aft ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Close-up view of the payload bay side of the aft fuselage bulkhead of the Orbiter Discovery. This image has a detailed portions of the Remote Manipulator System and the Orbiter Maneuvering System/Reaction Control System Pods. This photograph wa taken in the Orbiter Processing Facility at Kennedy Space Center. - Space Transportation System, Orbiter Discovery (OV-103), Lyndon B. Johnson Space Center, 2101 NASA Parkway, Houston, Harris County, TX

Digital Writing Practices: A Close Look at One Grade Three Author

ERIC Educational Resources Information Center

Kervin, Lisa; Mantei, Jessica

2016-01-01

This paper reports on the digital writing practices of a Grade Three primary school student as he used an iPad to plan, produce and share digital texts. The case study acknowledges that writing is undergoing a period of great change in many classrooms and works to show how a student author has interpreted and produced digital texts with new…

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

Ptitsyn, V.; Bai, M.; Roser, T.

Polarized proton beams are accelerated in RHIC to 250 GeV energy with the help of Siberian Snakes. The pair of Siberian Snakes in each RHIC ring holds the design spin tune at 1/2 to avoid polarization loss during acceleration. However, in the presence of closed orbit errors, the actual spin tune can be shifted away from the exact 1/2 value. It leads to a corresponding shift of locations of higher-order ('snake') resonances and limits the available betatron tune space. The largest closed orbit effect on the spin tune comes from the horizontal orbit angle between the two snakes. During RHICmore » Run in 2009 dedicated measurements with polarized proton beams were taken to verify the dependence of the spin tune on the local orbits at the Snakes. The experimental results are presented along with the comparison with analytical predictions.« less

The study of integration about measurable image and 4D production

NASA Astrophysics Data System (ADS)

Zhang, Chunsen; Hu, Pingbo; Niu, Weiyun

2008-12-01

In this paper, we create the geospatial data of three-dimensional (3D) modeling by the combination of digital photogrammetry and digital close-range photogrammetry. For large-scale geographical background, we make the establishment of DEM and DOM combination of three-dimensional landscape model based on the digital photogrammetry which uses aerial image data to make "4D" (DOM: Digital Orthophoto Map, DEM: Digital Elevation Model, DLG: Digital Line Graphic and DRG: Digital Raster Graphic) production. For the range of building and other artificial features which the users are interested in, we realize that the real features of the three-dimensional reconstruction adopting the method of the digital close-range photogrammetry can come true on the basis of following steps : non-metric cameras for data collection, the camera calibration, feature extraction, image matching, and other steps. At last, we combine three-dimensional background and local measurements real images of these large geographic data and realize the integration of measurable real image and the 4D production.The article discussed the way of the whole flow and technology, achieved the three-dimensional reconstruction and the integration of the large-scale threedimensional landscape and the metric building.

Optimal Lorentz-augmented spacecraft formation flying in elliptic orbits

NASA Astrophysics Data System (ADS)

Huang, Xu; Yan, Ye; Zhou, Yang

2015-06-01

An electrostatically charged spacecraft accelerates as it moves through the Earth's magnetic field due to the induced Lorentz force, providing a new means of propellantless electromagnetic propulsion for orbital maneuvers. The feasibility of Lorentz-augmented spacecraft formation flying in elliptic orbits is investigated in this paper. Assuming the Earth's magnetic field as a tilted dipole corotating with Earth, a nonlinear dynamical model that characterizes the orbital motion of Lorentz spacecraft in the vicinity of arbitrary elliptic orbits is developed. To establish a predetermined formation configuration at given terminal time, pseudospectral method is used to solve the optimal open-loop trajectories of hybrid control inputs consisted of Lorentz acceleration and thruster-generated control acceleration. A nontilted dipole model is also introduced to analyze the effect of dipole tilt angle via comparisons with the tilted one. Meanwhile, to guarantee finite-time convergence and system robustness against external perturbations, a continuous fast nonsingular terminal sliding mode controller is designed and the closed-loop system stability is proved by Lyapunov theory. Numerical simulations substantiate the validity of proposed open-loop and closed-loop control schemes, and the results indicate that an almost propellantless formation establishment can be achieved by choosing appropriate objective function in the pseudospectral method. Furthermore, compared to the nonsingular terminal sliding mode controller, the closed-loop controller presents superior convergence rate with only a bit more control effort. And the proposed controller can be applied in other Lorentz-augmented relative orbital control problems.

Current status of Polish Fireball Network

NASA Astrophysics Data System (ADS)

Wiśniewski, M.; Żołądek, P.; Olech, A.; Tyminski, Z.; Maciejewski, M.; Fietkiewicz, K.; Rudawska, R.; Gozdalski, M.; Gawroński, M. P.; Suchodolski, T.; Myszkiewicz, M.; Stolarz, M.; Polakowski, K.

2017-09-01

The Polish Fireball Network (PFN) is a project to monitor regularly the sky over Poland in order to detect bright fireballs. In 2016 the PFN consisted of 36 continuously active stations with 57 sensitive analogue video cameras and 7 high resolution digital cameras. In our observations we also use spectroscopic and radio techniques. A PyFN software package for trajectory and orbit determination was developed. The PFN project is an example of successful participation of amateur astronomers who can provide valuable scientific data. The network is coordinated by astronomers from Copernicus Astronomical Centre in Warsaw, Poland. In 2011-2015 the PFN cameras recorded 214,936 meteor events. Using the PFN data and the UFOOrbit software 34,609 trajectories and orbits were calculated. In the following years we are planning intensive modernization of the PFN network including installation of dozens of new digital cameras.

The Torino Impact Hazard Scale

NASA Astrophysics Data System (ADS)

Binzel, Richard P.

2000-04-01

Newly discovered asteroids and comets have inherent uncertainties in their orbit determinations owing to the natural limits of positional measurement precision and the finite lengths of orbital arcs over which determinations are made. For some objects making predictable future close approaches to the Earth, orbital uncertainties may be such that a collision with the Earth cannot be ruled out. Careful and responsible communication between astronomers and the public is required for reporting these predictions and a 0-10 point hazard scale, reported inseparably with the date of close encounter, is recommended as a simple and efficient tool for this purpose. The goal of this scale, endorsed as the Torino Impact Hazard Scale, is to place into context the level of public concern that is warranted for any close encounter event within the next century. Concomitant reporting of the close encounter date further conveys the sense of urgency that is warranted. The Torino Scale value for a close approach event is based upon both collision probability and the estimated kinetic energy (collision consequence), where the scale value can change as probability and energy estimates are refined by further data. On the scale, Category 1 corresponds to collision probabilities that are comparable to the current annual chance for any given size impactor. Categories 8-10 correspond to certain (probability >99%) collisions having increasingly dire consequences. While close approaches falling Category 0 may be no cause for noteworthy public concern, there remains a professional responsibility to further refine orbital parameters for such objects and a figure of merit is suggested for evaluating such objects. Because impact predictions represent a multi-dimensional problem, there is no unique or perfect translation into a one-dimensional system such as the Torino Scale. These limitations are discussed.

Semi-closed reduction of tripod fractures of zygoma under intraoperative assessment using ultrasonography.

PubMed

Soejima, Kazutaka; Sakurai, Hiroyuki; Nozaki, Motohiro; Kitazawa, Yoshihiko; Takeuchi, Masaki; Yamaki, Takashi; Kono, Taro

2009-04-01

We conducted semi-closed reduction of isolated tripod fractures of the zygoma through only a brow incision under intraoperative assessment with ultrasonography. Twenty-three patients with unilateral, non-comminuted tripod fractures of zygoma were selected for application of this method at Tokyo Women's Medical University and Tokyo Metropolitan Hiroo General Hospital between April 2002 and April 2006. Patients with orbital floor blowout fractures were excluded. A skin incision was made only at the lateral brow region and the reduction was performed by inserting an elevator beneath the zygomatic arch. The bone alignment was intraoperatively assessed by ultrasonography. When the reduction was accurate, the frontozygomatic suture was immobilised with a mini-plate under direct visualisation and transmaler Kirshner wire fixation was performed. The accuracy of the reduction and postoperative movement were evaluated by computed tomography (CT) scans taken at 1 and 6 months. In five cases, the DICOM (Digital Imaging and Communication in Medicine) data from the CT were analysed with 3D imaging software (V-works, CyberMed Co., Korea). In all cases, accurate reduction was obtained. The analysis of the 3D imaging data revealed that postoperative movement of bone fragment was minimal. When the accurate reduction was obtained under intraoperative assessment, the semi-closed reduction and one-plate fixation with transmaler Kirshner wire is enough to treat the simple tripod fractures of zygoma. This method is minimally invasive and takes less operative time.

Solar Orbiter Status Report

NASA Astrophysics Data System (ADS)

Gilbert, Holly; St. Cyr, Orville Chris; Mueller, Daniel; Zouganelis, Yannis; Velli, Marco

2017-08-01

With the delivery of the instruments to the spacecraft builder, the Solar Orbiter mission is in the midst of Integration & Testing phase at Airbus in Stevenage, U.K. This mission to “Explore the Sun-Heliosphere Connection” is the first medium-class mission of ESA’s Cosmic Vision 2015-2025 program and is being jointly implemented with NASA. The dedicated payload of 10 remote-sensing and in-situ instruments will orbit the Sun as close as 0.3 A.U. and will provide measurments from the photosphere into the solar wind. The three-axis stabilized spacecraft will use Venus gravity assists to increase the orbital inclination out of the ecliptic to solar latitudes as high as 34 degrees in the extended mission. The science team of Solar Orbiter has been working closely with the Solar Probe Plus scientists to coordinate observations between these two highly-complementary missions. This will be a status report on the mission development; the interested reader is referred to the recent summary by Müller et al., Solar Physics 285 (2013).

Saturn's Magnetic Field from the Cassini Grand Finale orbits

NASA Astrophysics Data System (ADS)

Dougherty, M. K.; Cao, H.; Khurana, K. K.; Hunt, G. J.; Provan, G.; Kellock, S.; Burton, M. E.; Burk, T. A.

2017-12-01

The fundamental aims of the Cassini magnetometer investigation during the Cassini Grand Finale orbits were determination of Saturn's internal planetary magnetic field and the rotation rate of the deep interior. The unique geometry of the orbits provided an unprecedented opportunity to measure the intrinsic magnetic field at close distances never before encountered. The surprising close alignment of Saturn's magnetic axis with its spin axis, known about since the days of Pioneer 11, has been a focus of the team's analysis since Cassini Saturn Orbit Insertion. However, the varying northern and southern magnetospheric planetary period oscillations, which fill the magnetosphere, has been a factor in masking the field signals from the interior. Here we describe an overview of the magnetometer results from the Grand Finale orbits, including confirmation of the extreme axisymmetric nature of the planetary magnetic field, implications for knowledge of the rotation rate and the behaviour of external magnetic fields (arising from the ring current, field aligned currents both at high and low latitudes and the modulating effect of the planetary period oscillations).

The Eccentric Behavior of Nearly Frozen Orbits

NASA Technical Reports Server (NTRS)

Sweetser, Theodore H.; Vincent, Mark A.

2013-01-01

Frozen orbits are orbits which have only short-period changes in their mean eccentricity and argument of periapse, so that they basically keep a fixed orientation within their plane of motion. Nearly frozen orbits are those whose eccentricity and argument of periapse have values close to those of a frozen orbit. We call them "nearly" frozen because their eccentricity vector (a vector whose polar coordinates are eccentricity and argument of periapse) will stay within a bounded distance from the frozen orbit eccentricity vector, circulating around it over time. For highly inclined orbits around the Earth, this distance is effectively constant over time. Furthermore, frozen orbit eccentricity values are low enough that these orbits are essentially eccentric (i.e., off center) circles, so that nearly frozen orbits around Earth are bounded above and below by frozen orbits.

Semiautomatic regional segmentation to measure orbital fat volumes in thyroid-associated ophthalmopathy. A validation study.

PubMed

Comerci, M; Elefante, A; Strianese, D; Senese, R; Bonavolontà, P; Alfano, B; Bonavolontà, B; Brunetti, A

2013-08-01

This study was designed to validate a novel semi-automated segmentation method to measure regional intra-orbital fat tissue volume in Graves' ophthalmopathy. Twenty-four orbits from 12 patients with Graves' ophthalmopathy, 24 orbits from 12 controls, ten orbits from five MRI study simulations and two orbits from a digital model were used. Following manual region of interest definition of the orbital volumes performed by two operators with different levels of expertise, an automated procedure calculated intra-orbital fat tissue volumes (global and regional, with automated definition of four quadrants). In patients with Graves' disease, clinical activity score and degree of exophthalmos were measured and correlated with intra-orbital fat volumes. Operator performance was evaluated and statistical analysis of the measurements was performed. Accurate intra-orbital fat volume measurements were obtained with coefficients of variation below 5%. The mean operator difference in total fat volume measurements was 0.56%. Patients had significantly higher intra-orbital fat volumes than controls (p<0.001 using Student's t test). Fat volumes and clinical score were significantly correlated (p<0.001). The semi-automated method described here can provide accurate, reproducible intra-orbital fat measurements with low inter-operator variation and good correlation with clinical data.

Digital Exclusion: Coming out from behind Closed Doors

ERIC Educational Resources Information Center

Watling, Sue

2011-01-01

Government visions of a digital future show little indication of how disabled people, reliant on access technology, will participate. Access technology has the potential to offer independent use of the Internet but many disabled people already face barriers that prevent them having equitable digital experiences. Multiple obstacles include high…

A SURVEY OF THE HIGH ORDER MULTIPLICITY OF NEARBY SOLAR-TYPE BINARY STARS WITH Robo-AO

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

Riddle, Reed L.; Bui, Khanh; Dekany, Richard G.

2015-01-20

We conducted a survey of nearby binary systems composed of main sequence stars of spectral types F and G in order to improve our understanding of the hierarchical nature of multiple star systems. Using Robo-AO, the first robotic adaptive optics instrument, we collected high angular resolution images with deep and well-defined detection limits in the Sloan Digital Sky Survey i' band. A total of 695 components belonging to 595 systems were observed. We prioritized observations of faint secondary components with separations over 10'' to quantify the still poorly constrained frequency of their subsystems. Of the 214 secondaries observed, 39 containmore » such subsystems; 19 of those were discovered with Robo-AO. The selection-corrected frequency of secondary subsystems with periods from 10{sup 3.5} to 10{sup 5} days is 0.12 ± 0.03, the same as the frequency of such companions to the primary. Half of the secondary pairs belong to quadruple systems where the primary is also a close pair, showing that the presence of subsystems in both components of the outer binary is correlated. The relatively large abundance of 2+2 quadruple systems is a new finding, and will require more exploration of the formation mechanism of multiple star systems. We also targeted close binaries with periods less than 100 yr, searching for their distant tertiary components, and discovered 17 certain and 2 potential new triples. In a subsample of 241 close binaries, 71 have additional outer companions. The overall frequency of tertiary components is not enhanced, compared to all (non-binary) targets, but in the range of outer periods from 10{sup 6} to 10{sup 7.5} days (separations on the order of 500 AU), the frequency of tertiary components is 0.16 ± 0.03, exceeding the frequency of similar systems among all targets (0.09) by almost a factor of two. Measurements of binary stars with Robo-AO allowed us to compute first orbits for 9 pairs and to improve orbits of another 11 pairs.« less

Closeup view if the starboard side of the crew compartment ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Close-up view if the starboard side of the crew compartment mid-deck of the Orbiter Discovery. This is a close up view of the galley for meal preparations. In the center right of the image is stowage lockers that are designated to store meals for the mission. This photograph was taken at Kennedy Space Center. - Space Transportation System, Orbiter Discovery (OV-103), Lyndon B. Johnson Space Center, 2101 NASA Parkway, Houston, Harris County, TX

Search for kinematic siblings of the sun based on data from the XHIP catalog

NASA Astrophysics Data System (ADS)

Bobylev, V. V.; Bajkova, A. T.

2014-06-01

From the XHIP catalogue, we have selected 1872 F-G-K stars with relative parallax measurement errors <20% and absolute values of their space velocities relative to the Sun <15 km s-1. For all these stars, we have constructed their Galactic orbits for 4.5 Gyr into the past using an axisymmetric Galactic potential model with allowance made for the perturbations from the spiral density wave. Parameters of the encounter with the solar orbit have been calculated for each orbit. We have detected three new stars whose Galactic orbits were close to the solar one during a long time interval in the past. These stars are HIP 43852, HIP 104047, and HIP 112158. The spectroscopic binary HIP 112158 is poorly suited for the role of a kinematic sibling of the Sun by its age and spectroscopic characteristics. For the single star HIP 43852 and the multiple system HIP 104047, this role is quite possible. We have also confirmed the status of our previously found candidates for close encounters, HIP 47399 and HIP 87382. The star HIP 87382 with a chemical composition very close to the solar one is currently the most likely candidate, because it persistently shows close encounters with the Sun on time scales of more than 3 Gyr when using various Galactic potential models both without and with allowance made for the influence of the spiral density wave.

Orbit correction in a linear nonscaling fixed field alternating gradient accelerator

DOE PAGES

Kelliher, D. J.; Machida, S.; Edmonds, C. S.; ...

2014-11-20

In a linear non-scaling FFAG the large natural chromaticity of the machine results in a betatron tune that varies by several integers over the momentum range. In addition, orbit correction is complicated by the consequent variation of the phase advance between lattice elements. Here we investigate how the correction of multiple closed orbit harmonics allows correction of both the COD and the accelerated orbit distortion over the momentum range.

Closeup view of the nose and landing gear on the ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Close-up view of the nose and landing gear on the forward section of the Orbiter Discovery in the Orbiter Processing Facility at Kennedy Space Center. The Orbiter is being supported by jack stands in the left and right portion of the view. The jack stands attach to the Orbiter at the four hoist attach points, two located on the forward fuselage and two on the aft fuselage. Note the access platforms that surround and nearly touch the orbiter. - Space Transportation System, Orbiter Discovery (OV-103), Lyndon B. Johnson Space Center, 2101 NASA Parkway, Houston, Harris County, TX

Transfer function verification and block diagram simplification of a very high-order distributed pole closed-loop servo by means of non-linear time-response simulation

NASA Technical Reports Server (NTRS)

Mukhopadhyay, A. K.

1975-01-01

Linear frequency domain methods are inadequate in analyzing the 1975 Viking Orbiter (VO75) digital tape recorder servo due to dominant nonlinear effects such as servo signal limiting, unidirectional servo control, and static/dynamic Coulomb friction. The frequency loop (speed control) servo of the VO75 tape recorder is used to illustrate the analytical tools and methodology of system redundancy elimination and high order transfer function verification. The paper compares time-domain performance parameters derived from a series of nonlinear time responses with the available experimental data in order to select the best possible analytical transfer function representation of the tape transport (mechanical segment of the tape recorder) from several possible candidates. The study also shows how an analytical time-response simulation taking into account most system nonlinearities can pinpoint system redundancy and overdesign stemming from a strictly empirical design approach. System order reduction is achieved through truncation of individual transfer functions and elimination of redundant blocks.

Stirring of a planetesimal swarm - The role of distant encounters

NASA Technical Reports Server (NTRS)

Weidenschilling, Stuart J.

1989-01-01

The viscous stirring algorithm developed by Stewart and Wetherill (1988) to treat the random velocities induced in planetesimals by their mutual gravitational perturbations encompasses only the scattering of bodies in crossing orbits by close encounters. Expressions are presently derived for the stirring rate due to distant encounters on the basis of three-body formalism, using a stirring rate that has the same mass-dependence as that for close encounters. The relative importance of both the close encounter and distant encounter mechanisms depends on the Safronov number. Perturbations by a planetary embryo in scenarios that involve explosive growth are found capable of affecting planetesimal evolution in noncrossing orbits.

Closed loop models for analyzing the effects of simulator characteristics. [digital simulation of human operators

NASA Technical Reports Server (NTRS)

Baron, S.; Muralidharan, R.; Kleinman, D. L.

1978-01-01

The optimal control model of the human operator is used to develop closed loop models for analyzing the effects of (digital) simulator characteristics on predicted performance and/or workload. Two approaches are considered: the first utilizes a continuous approximation to the discrete simulation in conjunction with the standard optimal control model; the second involves a more exact discrete description of the simulator in a closed loop multirate simulation in which the optimal control model simulates the pilot. Both models predict that simulator characteristics can have significant effects on performance and workload.

Processing of A New Digital Orthoimage Map of The Martian Western Hemisphere Using Data Obtained From The Mars Orbiter Camera At A Resolution of 256 Pixel/deg

NASA Astrophysics Data System (ADS)

Wählisch, M.; Niedermaier, G.; van Gasselt, S.; Scholten, F.; Wewel, F.; Roatsch, T.; Matz, K.-D.; Jaumann, R.

We present a new digital orthoimage map of Mars using data obtained from the CCD line scanner Mars Orbiter Camera (MOC) of the Mars Global Surveyor Mis- sion (MGS) [1,2]. The map covers the Mars surface from 0 to 180 West and from 60 South to 60 North with the MDIM2 resolution of 256 pixel/degree and size. Image data processing has been performed using multiple programs, developed by DLR, Technical University of Berlin [3], JPL, and the USGS. 4,339 Context and 183 Geodesy images [2] were included. After radiometric corrections, the images were Mars referenced [4], geometrically corrected [5] and orthoprojected using a global Martian Digital Terrain Model (DTM) with a resolution of 64 pixel/degree, developed at DLR and based on MGS Mars Orbiter Laser Altimeter (MOLA) data [6]. To elim- inate major differences in brightness between the individual images of the mosaics, high- and low-pass filter processing techniques were applied for each image. After filtering, the images were mosaicked without registering or using block adjustment techniques in order to improve the geometric quality. It turns out that the accuracy of the navigation data has such a good quality that the orthoimages fit very well to each other. When merging the MOC mosaic with the MOLA data using IHS- trans- formation, we recognized very good correspondence between these two datasets. We create a topographic image map of the Coprates region (MC­18) adding contour lines derived from the global DTM to the mosaic. These maps are used for geological and morphological interpretations in order to review and improve our current Viking-based knowledge about the Martian surface. References: [1] www.mssss.com, [2] Caplinger, M. and M. Malin, "The Mars Or- biter Camera Geodesy Campaign, JGR, in press, [3] Scholten, F., Vol XXXI, Part B2, Wien 1996, p.351-356, [4] naïf.jpl.nasa.gov, [5] R.L.Kirk. et al. (2001), "Geometric Calibration of the Mars Orbiter Cameras and Coalignment with Mars Orbiter Laser Altimeter", LPSC XXXII, [6] wufs.wustl.edu

Determination of ASPS performance for large payloads in the shuttle orbiter disturbance environment. [digital simulation

NASA Technical Reports Server (NTRS)

Keckler, C. R.; Kibler, K. S.; Powell, L. F.

1979-01-01

A high fidelity simulation of the annular suspension and pointing system (ASPS), its payload, and the shuttle orbiter was used to define the worst case orientations of the ASPS and its payload for the various vehicle disturbances, and to determine the performance capability of the ASPS under these conditions. The most demanding and largest proposed payload, the Solar Optical Telescope was selected for study. It was found that, in all cases, the ASPS more than satisfied the payload's requirements. It is concluded that, to satisfy facility class payload requirements, the ASPS or a shuttle orbiter free-drift mode (control system off) should be utilized.

Dual-spin attitude control for outer planet missions

NASA Technical Reports Server (NTRS)

Ward, R. S.; Tauke, G. J.

1977-01-01

The applicability of dual-spin technology to a Jupiter orbiter with probe mission was investigated. Basic mission and system level attitude control requirements were established and preliminary mechanization and control concepts developed. A comprehensive 18-degree-of-freedom digital simulation was utilized extensively to establish control laws, study dynamic interactions, and determined key sensitivities. Fundamental system/subsystem constraints were identified, and the applicability of dual-spin technology to a Jupiter orbiter with probe mission was validated.

High-Resolution Topography of Mercury from Messenger Orbital Stereo Imaging - the Southern Hemisphere Quadrangles

NASA Astrophysics Data System (ADS)

Preusker, F.; Oberst, J.; Stark, A.; Burmeister, S.

2018-04-01

We produce high-resolution (222 m/grid element) Digital Terrain Models (DTMs) for Mercury using stereo images from the MESSENGER orbital mission. We have developed a scheme to process large numbers, typically more than 6000, images by photogrammetric techniques, which include, multiple image matching, pyramid strategy, and bundle block adjustments. In this paper, we present models for map quadrangles of the southern hemisphere H11, H12, H13, and H14.

APAS with petals extended after undocking

NASA Image and Video Library

2002-10-16

STS112-E-05777 (16 Oct. 2002) --- Close-up view of the Orbiter Docking System (ODS) Androgynous Peripheral Attachment System (APAS) petals extended in the STS-112 orbiter Atlantis payload bay after undocking with the International Space Station.

M2 ocean tide parameters and the deceleration of the moon's mean longitude from satellite orbit data

NASA Technical Reports Server (NTRS)

Felsentreger, T. L.; Marsh, J. G.; Williamson, R. G.

1979-01-01

An estimation is made of the principal long-period spherical harmonic parameters in the representation of the M2 ocean tide from the orbital histories of the three satellites 1967-92A, Starlette, and GEOS 3. The data used are primarily the evolution of the orbital inclinations of the satellites in conjunction with the longitude of the ascending node from GEOS 3. Analysis procedure and analytic formulation, as well as ocean tidal parameter estimation and deceleration of the lunar mean longitude are outlined. The credibility of the M2 ocean tide solution is further enhanced by the close accord between the computed value for the deceleration of the lunar mean longitude and other recently reported estimates. It is evident from the results presented that studies of close earth satellite orbits are able to provide important information about the tidal forces acting on the earth.

KSC-04pd1823

NASA Image and Video Library

2004-09-01

KENNEDY SPACE CENTER, FLA. - At Vandenberg Air Force Base in California, workers begin closing the gap between the second and third stages of the Orbital Sciences Pegasus XL launch vehicle that will launch the Demonstration of Autonomous Rendezvous Technology (DART) spacecraft. DART was designed and built for NASA by Orbital Sciences Corporation as an advanced flight demonstrator to locate and maneuver near an orbiting satellite. DART weighs about 800 pounds and is nearly 6 feet long and 3 feet in diameter. The Pegasus XL will launch DART into a circular polar orbit of approximately 475 miles. DART is designed to demonstrate technologies required for a spacecraft to locate and rendezvous, or maneuver close to, other craft in space. Results from the DART mission will aid in the development of NASA's Crew Exploration Vehicle and will also assist in vehicle development for crew transfer and crew rescue capability to and from the International Space Station.

WASP-47 and the Origin of Hot Jupiters

NASA Astrophysics Data System (ADS)

Vanderburg, Andrew; Becker, Juliette; Latham, David W.; Adams, Fred; Bryan, Marta; Buchhave, Lars; Haywood, Raphaelle; Khain, Tali; Lopez, Eric; Malavolta, Luca; Mortier, Annelies; HARPS-N Consortium

2018-01-01

WASP-47 b is a transiting hot Jupiter in a system with two additional short-period transiting planets and a long-period outer Jovian companion. WASP-47 b is the only known hot Jupiter with such close-in companions and therefore may hold clues to the origins of hot Jupiter systems. We report on precise radial velocity observations of WASP-47 to measure planet masses and determine their orbits to high precision. Using these improved masses and orbital elements, we perform a dynamical analysis to constrain the inclination of the outer planet, which we find likely orbits near the same plane as the inner transiting system. A similar dynamical analysis for five other hot Jupiter systems with long-period companions around cool host stars (Teff < 6200 K) shows that these outer companions likely also orbit close to the plane of the hot Jupiters. These constraints disfavor hot Jupiter models involving strong dynamical interactions like Kozai-Lidov migration.

Close up view of the Commander's Seat on the Flight ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Close up view of the Commander's Seat on the Flight Deck of the Orbiter Discovery. Toward the right of the view and in front of te seat is the commander's Rotational Hand Controller. The pilot station has an identical controller. These control the acceleration in the roll pitch and yaw directions via the reaction control system and/or the orbiter maneuvering system while outside of Earth's atmosphere or via the orbiter's aerosurfaces wile in Earth's atmosphere when the atmospheric density permits the surfaces to be effective. There are a number of switches on the controller, most notably a trigger switch which is a push-to-talk switch for voice communication and a large button on top of the controller which is a switch to engage the backup flight system. This view was taken at Kennedy Space Center. - Space Transportation System, Orbiter Discovery (OV-103), Lyndon B. Johnson Space Center, 2101 NASA Parkway, Houston, Harris County, TX

Closeup view of the aft fuselage looking forward along the ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Close-up view of the aft fuselage looking forward along the approximate centerline of the Orbiter Discovery looking at the expansion nozzles of the Space Shuttle Main Engines (SSME) and the Orbiter Maneuvering System. Also in the view is the orbiter's body flap with a protective covering over the High-temperature Reusable Surface Insulation tiles on the surface facing the SSMEs. This image was taken inside the Orbiter Processing Facility at Kennedy Space Center. - Space Transportation System, Orbiter Discovery (OV-103), Lyndon B. Johnson Space Center, 2101 NASA Parkway, Houston, Harris County, TX

Closeup oblique view of the aft fuselage of the Orbiter ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Close-up oblique view of the aft fuselage of the Orbiter Discovery looking forward and port with the Space Shuttle Main Engines (SSME) and Orbiter Maneuvering System/Reaction Control System pods still in place. However. the heat shields have been removed from the SSMEs providing a good view toward the interior of the aft fuselage. This image was taken inside the Orbiter Processing Facility at Kennedy Space Center. - Space Transportation System, Orbiter Discovery (OV-103), Lyndon B. Johnson Space Center, 2101 NASA Parkway, Houston, Harris County, TX

Closeup oblique view of the aft fuselage of the Orbiter ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Close-up oblique view of the aft fuselage of the Orbiter Discovery looking forward and starboard with the Space Shuttle Main Engines (SSME) and Orbiter Maneuvering System/Reaction Control System pods removed. The openings for the SSMEs have been covered with a flexible barrier to create a positive pressure envelope inside of the aft fuselage. This image was taken inside the Orbiter Processing Facility at Kennedy Space Center. - Space Transportation System, Orbiter Discovery (OV-103), Lyndon B. Johnson Space Center, 2101 NASA Parkway, Houston, Harris County, TX

Closeup oblique view of the aft fuselage of the Orbiter ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Close-up oblique view of the aft fuselage of the Orbiter Discovery looking forward and starboard with the Space Shuttle Main Engines (SSME) and Orbiter Maneuvering System/Reaction Control System pods still in place. However. the heat shields have been removed from the SSMEs providing a good view toward the interior of the aft fuselage. This image was taken inside the Orbiter Processing Facility at Kennedy Space Center. - Space Transportation System, Orbiter Discovery (OV-103), Lyndon B. Johnson Space Center, 2101 NASA Parkway, Houston, Harris County, TX

15 CFR Appendix A to Part 950 - Schedule of User Fees for Access to NOAA Environmental Data

Code of Federal Regulations, 2011 CFR

2011-01-01

....00 2.00 Online In-Situ Digital Data 10.00 6.00 Data Poster 18.00 18.00 Shipping Service: For orders...: Mini Poster 1.00 1.00 Icosahedron Globe 0.50 3.00 Convert Data to Standard Image 5.00 5.00 Single Orbit... Paper Copy 2.00 2.00 Online In-Situ Digital Data 6.00 6.00 Data Poster 18.00 18.00 Shipping Service for...

MWIR imaging spectrometer with digital time delay integration for remote sensing and characterization of solar system objects

NASA Astrophysics Data System (ADS)

Kendrick, Stephen E.; Harwit, Alex; Kaplan, Michael; Smythe, William D.

2007-09-01

An MWIR TDI (Time Delay and Integration) Imager and Spectrometer (MTIS) instrument for characterizing from orbit the moons of Jupiter and Saturn is proposed. Novel to this instrument is the planned implementation of a digital TDI detector array and an innovative imaging/spectroscopic architecture. Digital TDI enables a higher SNR for high spatial resolution surface mapping of Titan and Enceladus and for improved spectral discrimination and resolution at Europa. The MTIS imaging/spectroscopic architecture combines a high spatial resolution coarse wavelength resolution imaging spectrometer with a hyperspectral sensor to spectrally decompose a portion of the data adjacent to the data sampled in the imaging spectrometer. The MTIS instrument thus maps with high spatial resolution a planetary object while spectrally decomposing enough of the data that identification of the constituent materials is highly likely. Additionally, digital TDI systems have the ability to enable the rejection of radiation induced spikes in high radiation environments (Europa) and the ability to image in low light levels (Titan and Enceladus). The ability to image moving objects that might be missed utilizing a conventional TDI system is an added advantage and is particularly important for characterizing atmospheric effects and separating atmospheric and surface components. This can be accomplished with on-orbit processing or collecting and returning individual non co-added frames.

Orbital Evolution of Jupiter-family Comets

NASA Astrophysics Data System (ADS)

Ipatov, S. I.; Mather, J. C.

2004-05-01

The orbital evolution of more than 25,000 Jupiter-family comets (JFCs) under the gravitational influence of planets was studied. After 40 Myr one considered object (with initial orbit close to that of Comet 88P) got aphelion distance Q<3.5 AU, and it moved in orbits with semi-major axis a=2.60-2.61 AU, perihelion distance 1.71.4 AU, Q<2.6 AU, e=0.2-0.3, and i=9-33 deg for 8 Myr (and it had Q<3 AU for 100 Myr). So JFCs can rarely get typical asteroid orbits and move in them for Myrs. In our opinion, it can be possible that Comet 133P (Elst--Pizarro) moving in a typical asteroidal orbit was earlier a JFC and it circulated its orbit also due to non-gravitational forces. JFCs got near-Earth object (NEO) orbits more often than typical asteroidal orbits. A few JFCs got Earth-crossing orbits with a<2 AU and Q<4.2 AU and moved in such orbits for more than 1 Myr (up to tens or even hundreds of Myrs). Three considered former JFCs even got inner-Earth orbits (with Q<0.983 AU) or Aten orbits for Myrs. The probability of a collision of one of such objects, which move for millions of years inside Jupiter's orbit, with a terrestrial planet can be greater than analogous total probability for thousands other objects. Results obtained by the Bulirsch-Stoer method and by a symplectic method were mainly similar (except for probabilities of close encounters with the Sun when they were high). Our results show that the trans-Neptunian belt can provide a significant portion of NEOs, or the number of trans-Neptunian objects migrating inside solar system could be smaller than it was earlier considered, or most of 1-km former trans-Neptunian objects that had got NEO orbits disintegrated into mini-comets and dust during a smaller part of their dynamical lifetimes if these lifetimes are not small. The obtained results show that during the accumulation of the giant planets the total mass of icy bodies delivered to the Earth could be about the mass of water in Earth's oceans. Several our papers on this problem were put in http://arXiv.org/format/astro-ph/ (e.g., 0305519, 0308448). This work was supported by NASA (NAG5-10776) and INTAS (00-240).

Survival of extrasolar giant planet moons in planet-planet scattering

NASA Astrophysics Data System (ADS)

CIAN HONG, YU; Lunine, Jonathan; Nicholson, Phillip; Raymond, Sean

2015-12-01

Planet-planet scattering is the best candidate mechanism for explaining the eccentricity distribution of exoplanets. Here we study the survival and dynamics of exomoons under strong perturbations during giant planet scattering. During close encounters, planets and moons exchange orbital angular momentum and energy. The most common outcomes are the destruction of moons by ejection from the system, collision with the planets and the star, and scattering of moons onto perturbed but still planet-bound orbits. A small percentage of interesting moons can remain bound to ejected (free-floating) planets or be captured by a different planet. Moons' survival rate is correlated with planet observables such as mass, semi-major axis, eccentricity and inclination, as well as the close encounter distance and the number of close encounters. In addition, moons' survival rate and dynamical outcomes are predetermined by the moons' initial semi-major axes. The survival rate drops quickly as moons' distances increase, but simulations predict a good chance of survival for the Galilean moons. Moons with different dynamical outcomes occupy different regions of orbital parameter space, which may enable the study of moons' past evolution. Potential effects of planet obliquity evolution caused by close encounters on the satellites’ stability and dynamics will be reported, as well as detailed and systematic studies of individual close encounter events.

A simple second-order digital phase-locked loop.

NASA Technical Reports Server (NTRS)

Tegnelia, C. R.

1972-01-01

A simple second-order digital phase-locked loop has been designed for the Viking Orbiter 1975 command system. Excluding analog-to-digital conversion, implementation of the loop requires only an adder/subtractor, two registers, and a correctable counter with control logic. The loop considers only the polarity of phase error and corrects system clocks according to a filtered sequence of this polarity. The loop is insensitive to input gain variation, and therefore offers the advantage of stable performance over long life. Predictable performance is guaranteed by extreme reliability of acquisition, yet in the steady state the loop produces only a slight degradation with respect to analog loop performance.

Digital spiral-slit for bi-photon imaging

NASA Astrophysics Data System (ADS)

McLaren, Melanie; Forbes, Andrew

2017-04-01

Quantum ghost imaging using entangled photon pairs has become a popular field of investigation, highlighting the quantum correlation between the photon pairs. We introduce a technique using spatial light modulators encoded with digital holograms to recover both the amplitude and the phase of the digital object. Down-converted photon pairs are entangled in the orbital angular momentum basis, and are commonly measured using spiral phase holograms. Consequently, by encoding a spiral ring-slit hologram into the idler arm, and varying it radially we can simultaneously recover the phase and amplitude of the object in question. We demonstrate that a good correlation between the encoded field function and the reconstructed images exists.

ORBITAL SOLUTIONS FOR TWO YOUNG, LOW-MASS SPECTROSCOPIC BINARIES IN OPHIUCHUS

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

Rosero, V.; Prato, L.; Wasserman, L. H.

2011-01-15

We report the orbital parameters for ROXR1 14 and RX J1622.7-2325Nw, two young, low-mass, and double-lined spectroscopic binaries recently discovered in the Ophiuchus star-forming region. Accurate orbital solutions were determined from over a dozen high-resolution spectra taken with the Keck II and Gemini South telescopes. These objects are T Tauri stars with mass ratios close to unity and periods of {approx}5 and {approx}3 days, respectively. In particular, RX J1622.7-2325Nw shows a non-circularized orbit with an eccentricity of 0.30, higher than any other short-period pre-main-sequence (PMS) spectroscopic binary known to date. We speculate that the orbit of RX J1622.7-2325Nw has notmore » yet circularized because of the perturbing action of a {approx}1'' companion, itself a close visual pair. A comparison of known young spectroscopic binaries (SBs) and main-sequence (MS) SBs in the eccentricity-period plane shows an indistinguishable distribution of the two populations, implying that orbital circularization occurs in the first 1 Myr of a star's lifetime. With the results presented in this paper we increase by {approx}4% the small sample of PMS spectroscopic binary stars with known orbital elements.« less

Closeup view of the reflective insulation protecting the Crew Compartment ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Close-up view of the reflective insulation protecting the Crew Compartment bulkhead, orbiter structure and landing gear housing in the void created by the removal of the Forward Reaction Control System Module from the forward section of the Orbiter Discovery. This image was taken from the service platform in the Orbiter Processing Facility at Kennedy Space Center. - Space Transportation System, Orbiter Discovery (OV-103), Lyndon B. Johnson Space Center, 2101 NASA Parkway, Houston, Harris County, TX

Detail view of the port side of the payload bay ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Detail view of the port side of the payload bay of the Orbiter Discovery. This view shows Remote Manipulator System, Canadarm, sensors in the center of the image and a close-up view of a small segment of the orbiter's radiator panel. This photograph was taken in the Orbiter Processing Facility at the Kennedy Space Center. - Space Transportation System, Orbiter Discovery (OV-103), Lyndon B. Johnson Space Center, 2101 NASA Parkway, Houston, Harris County, TX

The variations in eccentricity and apse precession rate of a narrow ring perturbed by a close satellite

NASA Technical Reports Server (NTRS)

Borderies, N.; Goldreich, P.; Tremaine, S.

1983-01-01

The first-order perturbations of orbital eccentricity and apse precession rate for the case of a narrow ring, due to a close satellite whose orbit is also eccentric, are described by means of a Hamiltonian. The present treatment covers cases in which the satellite crosses the ring, and the level curves of the Hamiltonian are displayed for several parameter values. The results obtained are applied to the interaction of Saturn's F ring with its inner shepherd satellite.

Spectral types of four binaries based on photometric observations

NASA Astrophysics Data System (ADS)

Shimanskii, V. V.; Bikmaev, I. F.; Borisov, N. V.; Vlasyuk, V. V.; Galeev, A. I.; Sakhibullin, N. A.; Spiridonova, O. I.

2008-09-01

We present results of photometric and spectroscopic observations of four close binaries with subdwarf B components: PG 0918+029, PG 1000+408, PG 1116+301, PG 0001+275. We discovered that PG 1000+408 is a close binary, with the most probable orbital period being P orb = 1.041145 day. Based on a comparison of the observed light curves at selected orbital phases and theoretical predictions for their variations, all the systems are classified as doubly degenerate binaries with low-luminosity white-dwarf secondaries.

Youth Culture and Digital Media: New Literacies for New Times

ERIC Educational Resources Information Center

Hull, Glynda A.

2003-01-01

In this article, the author discusses the "Digital Underground Storytelling for Youth" (DUSTY), a collection of after-school, evening, and summer programs that is a university-community collaborative aimed at closing the "digital divide." At DUSTY the goal is to position participants to tell stories about self and community, and to use those…

"Impossible Is Nothing": Expressing Difficult Knowledge through Digital Storytelling

ERIC Educational Resources Information Center

Johnson, Lauren; Kendrick, Maureen

2017-01-01

The study focuses on a digital storytelling project conducted in a school district's transition program, in which adolescent refugee and immigrant English learners were invited to share aspects of their identities and social worlds through a range of modes. In this article, the authors look closely at one student's digital story through a…

How to Kill a Journalism School: The Digital Sublime in the Discourse of Discontinuance

ERIC Educational Resources Information Center

McDevitt, Michael; Sindorf, Shannon

2012-01-01

The authors argue that journalism's uncertain identity in academia has made it vulnerable to unreflective instrumentalism in the digital era. They show how instrumentalism intertwined with the digital sublime constitutes a rhetorically resonate rationale for closing a journalism school. Evidence comes from documents and testimony associated with…

Small Wonders Close Encounters

ERIC Educational Resources Information Center

Kniseley, MacGregor; Capraro, Karen

2013-01-01

This article introduces students to the world of digital microscopy. Looking at small objects through a digital microscope is like traveling through a foreign country for the first time. The experience is new, engaging, and exciting. A handheld digital microscope is an essential tool in a 21st century teacher's toolkit and the perfect tool to…

Digital PI-PD controller design for arbitrary order systems: Dominant pole placement approach.

PubMed

Dincel, Emre; Söylemez, Mehmet Turan

2018-05-02

In this paper, a digital PI-PD controller design method is proposed for arbitrary order systems with or without time-delay to achieve desired transient response in the closed-loop via dominant pole placement approach. The digital PI-PD controller design problem is solved by converting the original problem to the digital PID controller design problem. Firstly, parametrization of the digital PID controllers which assign dominant poles to desired location is done. After that the subset of digital PID controller parameters in which the remaining poles are located away from the dominant pole pair is found via Chebyshev polynomials. The obtained PID controller parameters are then transformed into the PI-PD controller parameters by considering the closed-loop controller zero and the design is completed. Success of the proposed design method is firstly demonstrated on an example transfer function and compared with the well-known PID controller methods from the literature through simulations. After that the design method is implemented on the fan and plate laboratory system in a real environment. Copyright © 2018 ISA. Published by Elsevier Ltd. All rights reserved.

End effector on orbiter's RMS arm

NASA Image and Video Library

2001-03-13

STS102-E-5201 (13 March 2001) --- A view of the interior of the end effector apparatus on the end of the Canadian-built remote manipulator system (RMS) arm. The photograph was taken with a digital still camera.

Advanced X-Ray Inspection of Reinforced Carbon Composite Materials on the Orbiter Leading Edge Structural Subsystem (LESS)

NASA Technical Reports Server (NTRS)

Hernandez, Jose M.; Berry, Robert F.; Osborn, Robin; Bueno, Clifford; Osterlitz, Mark; Mills, Richard; Morris, Philip; Phalen, Robert; McNab, Jim; Thibodeaux, Tahanie;

Absence of periodic orbits in digital memcomputing machines with solutions

NASA Astrophysics Data System (ADS)

Di Ventra, Massimiliano; Traversa, Fabio L.

2017-10-01

In Traversa and Di Ventra [Chaos 27, 023107 (2017)] we argued, without proof, that if the non-linear dynamical systems with memory describing the class of digital memcomputing machines (DMMs) have equilibrium points, then no periodic orbits can emerge. In fact, the proof of such a statement is a simple corollary of a theorem already demonstrated in Traversa and Di Ventra [Chaos 27, 023107 (2017)]. Here, we point out how to derive such a conclusion. Incidentally, the same demonstration implies absence of chaos, a result we have already demonstrated in Di Ventra and Traversa [Phys. Lett. A 381, 3255 (2017)] using topology. These results, together with those in Traversa and Di Ventra [Chaos 27, 023107 (2017)], guarantee that if the Boolean problem the DMMs are designed to solve has a solution, the system will always find it, irrespective of the initial conditions.

Retarding potential analyzer for the Pioneer-Venus Orbiter Mission

NASA Technical Reports Server (NTRS)

Knudsen, W. C.; Bakke, J.; Spenner, K.; Novak, V.

1979-01-01

The retarding potential analyzer on the Pioneer-Venus Orbiter Mission has been designed to measure most of the thermal plasma parameters within and near the Venusian ionosphere. Parameters include total ion concentration, concentrations of the more abundant ions, ion temperatures, ion drift velocity, electron temperature, and low-energy (0-50 eV) electron distribution function. To accomplish these measurements on a spinning vehicle with a small telemetry bit rate, several functions, including decision functions not previously used in RPA's, have been developed and incorporated into this instrument. The more significant functions include automatic electrometer ranging with background current compensation; digital, quadratic retarding potential step generation for the ion and low-energy electron scans; a current sampling interval of 2 ms throughout all scans; digital logic inflection point detection and data selection; and automatic ram direction detection. Extensive numerical simulation and plasma chamber tests have been conducted to verify adequacy of the design for the Pioneer Mission.

General view looking aft along the starboard side of the ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

General view looking aft along the starboard side of the Orbiter Discovery in the Vehicle Assembly Building at NASA's Kennedy Space Center. This view shows a close up view of the reinforced carbon-carbon leading edge of the Orbiter wing. - Space Transportation System, Orbiter Discovery (OV-103), Lyndon B. Johnson Space Center, 2101 NASA Parkway, Houston, Harris County, TX

KSC-04pd1598

NASA Image and Video Library

2004-07-14

KENNEDY SPACE CENTER, FLA. - At Vandenberg Air Force Base in California, Orbital Sciences technicians observe closely the movement of the DART (Demonstration for Autonomous Rendezvous Technology) flight demonstrator as it is lowered onto a stand. The spacecraft was developed to prove technologies for locating and maneuvering near an orbiting satellite. Future applications of technologies developed by the DART project will benefit the nation in future space-vehicle systems development requiring in-space assembly, services or other autonomous rendezvous operations. Designed and developed for NASA by Orbital Sciences Corporation in Dulles, Va., the DART spacecraft will be launched on a Pegasus launch vehicle. At about 40,000 feet over the Pacific Ocean, the Pegasus will be released from Orbital’s Stargazer L-1011 aircraft, fire its rocket motors and boost DART into a polar orbit approximately 472 miles by 479 miles. Once in orbit, DART will rendezvous with a target satellite, the Multiple Paths, Beyond-Line-of-Site Communications satellite, also built by Orbital Sciences. DART will then perform several close proximity operations, such as moving toward and away from the satellite using navigation data provided by onboard sensors. DART is scheduled for launch no earlier than Oct. 18.

Analysis of impulsive maneuvers to keep orbits around the asteroid 2001SN263

NASA Astrophysics Data System (ADS)

Santos, Willer G.; Prado, Antonio F. B. A.; Oliveira, Geraldo M. C.; Santos, Leonardo B. T.

2018-01-01

The strongly perturbed environment of a small body, such as an asteroid, can complicate the prediction of orbits used for close proximity operations. Inaccurate predictions may make the spacecraft collide with the asteroid or escape to the deep space. The main forces acting in the dynamics come from the solar radiation pressure and from the body's weak gravity field. This paper investigates the feasibility of using bi-impulsive maneuvers to avoid the aforementioned non-desired phenomena (collisions and escapes) by connecting orbits around the triple system asteroid 2001SN263, which is the target of a proposed Brazilian space mission. In terms of a mathematical formulation, a recently presented rotating dipole model is considered with oblateness in both primaries. In addition, a "two-point boundary value problem" is solved to find a proper transfer trajectory. The results presented here give support to identifying the best strategy to find orbits for close proximity operations, in terms of long orbital lifetimes and low delta-V consumptions. Numerical results have also demonstrated the significant influence of the spacecraft orbital elements (semi-major axis and eccentricity), angular position of the Sun and spacecraft area-to-mass ratio, in the performance of the bi-impulsive maneuver.

Pioneer probe mission with orbiter option

NASA Technical Reports Server (NTRS)

1975-01-01

A spacecraft is described which is based on Pioneer 10 and 11, and existing propulsion technology; it can transport and release a probe for entry into Jupiter's atmosphere, and subsequently maneuver to place the spacecraft in orbit about Jupiter. Orbital operations last 3 years and include maneuvers to provide multiple close satellite encounters which allow the orbit to be significantly changed to explore different parts of the magnetosphere. A mission summary, a guide to related documents, and background information about Jupiter are presented along with mission analysis over the complete mission profile. Other topics discussed include the launch, interplanetary flight, probe release and orbit deflection, probe entry, orbit selection, orbit insertion, periapsis raising, spacecraft description, and the effects of Jupiter's radiation belt on both orbiter and the probe.

Analysis of GOES imagery and digitized data for the SEV-UPS period, August 1979

NASA Technical Reports Server (NTRS)

Bowley, C. J.; Burke, H. H. K.; Barnes, J. C.

1981-01-01

In support of the Southeastern Virginia Urban Plume Study (SEV-UPS), GOES satellite imagery was analyzed for the month of August 1979. The analyzed GOES images provide an additional source of meteorological input useful in the evaluation of air quality data collected during the month long period of the SEV-UPS experiment. In addition to the imagery analysis, GOES digitized data were analyzed for the period of August 6 to 11, during which a regional haze pattern was detectable in the imagery. The results of the study indicate that the observed haze patterns correspond closely with areas shown in surface based measurements to have reduced visibilities and elevated pollution levels. Moreover, the results of the analysis of digitized data indicate that digital reflectance counts can be directly related to haze intensity both over land and ocean. The model results agree closely with the observed GOES digital reflectance counts, providing further indication that satellite remote sensing can be a useful tool for monitoring regional elevated pollution episodes.

Digital pyramid wavefront sensor with tunable modulation.

PubMed

Akondi, Vyas; Castillo, Sara; Vohnsen, Brian

2013-07-29

The pyramid wavefront sensor is known for its high sensitivity and dynamic range that can be tuned by mechanically altering its modulation amplitude. Here, a novel modulating digital scheme employing a reflecting phase only spatial light modulator is demonstrated. The use of the modulator allows an easy reconfigurable pyramid with digital control of the apex angle and modulation geometry without the need of any mechanically moving parts. Aberrations introduced by a 140-actuator deformable mirror were simultaneously sensed with the help of a commercial Hartmann-Shack wavefront sensor. The wavefronts reconstructed using the digital pyramid wavefront sensor matched very closely with those sensed by the Hartmann-Shack. It is noted that a tunable modulation is necessary to operate the wavefront sensor in the linear regime and to accurately sense aberrations. Through simulations, it is shown that the wavefront sensor can be extended to astronomical applications as well. This novel digital pyramid wavefront sensor has the potential to become an attractive option in both open and closed loop adaptive optics systems.

Periodic Trojan-type orbits in the earth-sun system

NASA Technical Reports Server (NTRS)

Weissman, P. R.; Wetherill, G. W.

1974-01-01

Periodic orbits about the triangular equilibrium points are found for the planar restricted three-body problem using the earth-sun system. The maximum semimajor axis for tadpole orbits ranges from the infinitesimal orbit at 1.000 AU to the near-limiting orbit at 1.00285 AU. Horseshoe orbits are found for 1.0029 to 1.0080 AU, larger horseshoes being unstable because of close approaches to the earth. Using stability tests devised by Rabe (1961, 1962), the limit of stability for nonperiodic orbits is found to occur for maximum semimajor axes near 1.0020 AU. In addition, near-periodic tadpole orbits appear to be stable against perturbations by Jupiter and Venus for periods of at least 10,000 yr. The possibility that minor planets actually exist in such orbits is considered.

From Online to Ubiquitous Cities: The Technical Transformation of Virtual Communities

NASA Astrophysics Data System (ADS)

Anthopoulos, Leonidas; Fitsilis, Panos

Various digital city projects, from the online cases (e.g. the America on Line) to the ubiquitous cities of South Korea, have achieved in creating technically 'physical' areas for the virtual communities, which share knowledge of common interest. Moreover, digital cities can succeed in simplifying citizen access to public information and services. Early digital cities deliver 'smart' and social services to citizens even with no digital skills, closing digital divide and establishing digital areas of trust in local communities. This paper presents the evolution of the digital cities, from the web to the ubiquitous architecture. It uses the latest digital city architecture and the current conditions of the digital city of Trikala (Greece), in order to present the evolution procedure of a digital city.

Dynamical Effects of Stellar Companions

NASA Astrophysics Data System (ADS)

Naoz, Smadar

2016-10-01

The fraction of stellar binaries in the field is extremely high (about 40% - 70% forM > 1M⊙ stars), and thus, given this frequency, a high fraction of all exoplanetary systems may reside in binaries. While close-in giant planets tend to be found preferentially in binary stellar systems it seems that the frequency of giant planets in close binaries (>100-1000 AU) is significantly lower than in the overall population. Stellar companions gravitational perturbations may significantly alter the planetary orbits around their partner on secular timescales. They can drive planets to large eccentric orbits which can either result in plunging these planets into the star or shrinking their orbits and forming short period planets. These planets typically are misaligned with the parent star.

Close up view of the pair of Rudder Pedals in ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Close up view of the pair of Rudder Pedals in the Commander's Satiation on the Flight Deck of the Orbiter Discovery. The rudder pedals command orbiter acceleration in yaw by positioning the rudder during atmospheric flight. However, because the flight control software automatically performs turn coordination during banking maneuvers, the rudder pedals are not operationally used during glided flight. It is not until after touchdown that the crew uses them for nose wheel steering during rollout. Depressing the upper portion of the rudder pedals provides braking. Differential braking may also be used for directional control during rollout. This view was take at Johnson Space Center. - Space Transportation System, Orbiter Discovery (OV-103), Lyndon B. Johnson Space Center, 2101 NASA Parkway, Houston, Harris County, TX

KSC-04pd1691

NASA Image and Video Library

2004-08-31

KENNEDY SPACE CENTER, FLA. - Workers in the Orbiter Processing Facility prepare to close the nose wheel doors on Atlantis in preparation for the expected impact of Hurricane Frances on Saturday. Preparations at KSC include powering down the Space Shuttle orbiters, closing their payload bay doors and stowing their landing gear. They are also taking precautions against flooding by moving spacecraft hardware off the ground and sandbagging facilities. The Orbiter Processing Facility is constructed of concrete and steel and was designed to withstand winds of 105 mph. The Vehicle Assembly Building is constructed of concrete and steel and was designed to withstand winds of 125 mph. Other payload and flight hardware support facilities can endure winds of 110 mph. Launch pads and the Payload Hazardous Servicing Facility can withstand 125-mph winds.

KSC-04pd1690

NASA Image and Video Library

2004-08-31

KENNEDY SPACE CENTER, FLA. - Workers in the Orbiter Processing Facility prepare to close the nose wheel doors on Atlantis in preparation for the expected impact of Hurricane Frances on Saturday. Preparations at KSC include powering down the Space Shuttle orbiters, closing their payload bay doors and stowing their landing gear. They are also taking precautions against flooding by moving spacecraft hardware off the ground and sandbagging facilities. The Orbiter Processing Facility is constructed of concrete and steel and was designed to withstand winds of 105 mph. The Vehicle Assembly Building is constructed of concrete and steel and was designed to withstand winds of 125 mph. Other payload and flight hardware support facilities can endure winds of 110 mph. Launch pads and the Payload Hazardous Servicing Facility can withstand 125-mph winds.

KSC-04pd1689

NASA Image and Video Library

2004-08-31

KENNEDY SPACE CENTER, FLA. - Workers in the Orbiter Processing Facility prepare to close the nose wheel doors on Atlantis in preparation for the expected impact of Hurricane Frances on Saturday. Preparations at KSC include powering down the Space Shuttle orbiters, closing their payload bay doors and stowing their landing gear. They are also taking precautions against flooding by moving spacecraft hardware off the ground and sandbagging facilities. The Orbiter Processing Facility is constructed of concrete and steel and was designed to withstand winds of 105 mph. The Vehicle Assembly Building is constructed of concrete and steel and was designed to withstand winds of 125 mph. Other payload and flight hardware support facilities can endure winds of 110 mph. Launch pads and the Payload Hazardous Servicing Facility can withstand 125-mph winds.

An integral equation formulation for predicting radiation patterns of a space shuttle annular slot antenna

NASA Technical Reports Server (NTRS)

Jones, J. E.; Richmond, J. H.

1974-01-01

An integral equation formulation is applied to predict pitch- and roll-plane radiation patterns of a thin VHF/UHF (very high frequency/ultra high frequency) annular slot communications antenna operating at several locations in the nose region of the space shuttle orbiter. Digital computer programs used to compute radiation patterns are given and the use of the programs is illustrated. Experimental verification of computed patterns is given from measurements made on 1/35-scale models of the orbiter.

Testing of advanced technique for linear lattice and closed orbit correction by modeling its application for iota ring at Fermilab

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

Romanov, A.

Many modern and most future accelerators rely on precise configuration of lattice and trajectory. The Integrable Optics Test Accelerator (IOTA) at Fermilab that is coming to final stages of construction will be used to test advanced approaches of control over particles dynamics. Various experiments planned at IOTA require high flexibility of lattice configuration as well as high precision of lattice and closed orbit control. Dense element placement does not allow to have ideal configuration of diagnostics and correctors for all planned experiments. To overcome this limitations advanced method of lattice an beneficial for other machines. Developed algorithm is based onmore » LOCO approach, extended with various sets of other experimental data, such as dispersion, BPM BPM phase advances, beam shape information from synchrotron light monitors, responses of closed orbit bumps to variations of focusing elements and other. Extensive modeling of corrections for a big number of random seed errors is used to illustrate benefits from developed approach.« less

Tidal Interaction among Red Giants Close Binary Systems in APOGEE Database

NASA Astrophysics Data System (ADS)

Sun, Meng; Arras, Phil; Majewski, Steven R.; Troup, Nicholas William; Weinberg, Nevin N.

2017-01-01

Motivated by the newly discovered close binary systems in the Apache Point Observatory Galactic Evolution Experiment (APOGEE-1), the tidal evolution of binaries containing a red giant branch (RGB) star with a stellar or substellar companion was investigated. The tide raised by the companion in the RGB star leads to exchange of angular momentum between the orbit and the stellar spin, causing the orbit to contract. The tidal dissipation rate is computed using turbulent viscosity acting on the equilibrium tidal flow, where careful attention is paid to the effects of reduced viscosity for close-in companions. Evolutionary models for the RGB stars, from the zero-age main sequence to the present, were acquired from the MESA code. "Standard" turbulent viscosity gives rise to such a large orbital decay that many observed systems have decay times much shorter than the RGB evolution time. Several theories for "reduced" turbulent viscosity are investigated, and reduce the number of systems with uncomfortably short decay times.

Migration-driven diversity of super-Earth compositions

NASA Astrophysics Data System (ADS)

Raymond, Sean N.; Boulet, Thibault; Izidoro, Andre; Esteves, Leandro; Bitsch, Bertram

2018-06-01

A leading model for the origin of super-Earths proposes that planetary embryos migrate inward and pile up on close-in orbits. As large embryos are thought to preferentially form beyond the snow line, this naively predicts that most super-Earths should be very water-rich. Here we show that the shortest-period planets formed in the migration model are often purely rocky. The inward migration of icy embryos through the terrestrial zone accelerates the growth of rocky planets via resonant shepherding. We illustrate this process with a simulation that provided a match to the Kepler-36 system of two planets on close orbits with very different densities. In the simulation, two super-Earths formed in a Kepler-36-like configuration; the inner planet was pure rock while the outer one was ice-rich. We conclude from a suite of simulations that the feeding zones of close-in super-Earths are likely to be broad and disconnected from their final orbital radii.

Spectroscopic orbits of symbiotic stars - Preliminary results

NASA Technical Reports Server (NTRS)

Garcia, M. R.

1986-01-01

The present search for radial velocity variations due to orbital motions in symbiotic stars involved observations of 17 such stars at approximately 1-month intervals, as well as of radial velocity variations in the M-giant primary in nine stars. The observed radial velocity curves are commensurate with those expected from a group of binaries having random sin i and about 20 km/sec orbital velocities. Four of the orbital periods thus suggested for seven stars confirm previously known photometric periods, while one confirms a previously known orbital period and two are completely new. Knowledge of the orbits allows identification of those symbiotics that are close to filling their Roche lobes.

Analysis of the upper massif of the craniofacial with the radial method – practical use

PubMed Central

Lepich, Tomasz; Dąbek, Józefa; Stompel, Daniel; Gielecki, Jerzy S.

2011-01-01

Introduction The analysis of the upper massif of the craniofacial (UMC) is widely used in many fields of science. The aim of the study was to create a high resolution computer system based on a digital information record and on vector graphics, that could enable dimension measuring and evaluation of craniofacial shape using the radial method. Material and methods The study was carried out on 184 skulls, in a good state of preservation, from the early middle ages. The examined skulls were fixed into Molisson's craniostat in the author's own modification. They were directed in space towards the Frankfurt plane and photographed in frontal norm with a digital camera. The parameters describing the plane and dimensional structure of the UMC and orbits were obtained thanks to the computer analysis of the function recordings picturing the craniofacial structures and using software combining raster graphics with vector graphics. Results It was compared mean values of both orbits separately for male and female groups. In female skulls the comparison of the left and right side did not show statistically significant differences. In male group, higher values were observed for the right side. Only the circularity index presented higher values for the left side. Conclusions Computer graphics with the software used for analysing digital pictures of UMC and orbits increase the precision of measurements as well as the calculation possibilities. Recognition of the face in the post mortem examination is crucial for those working on identification in anthropology and criminology laboratories. PMID:22291834

Predicting Instability Timescales in Closely-Packed Planetary Systems

NASA Astrophysics Data System (ADS)

Tamayo, Daniel; Hadden, Samuel; Hussain, Naireen; Silburt, Ari; Gilbertson, Christian; Rein, Hanno; Menou, Kristen

2018-04-01

Many of the multi-planet systems discovered around other stars are maximally packed. This implies that simulations with masses or orbital parameters too far from the actual values will destabilize on short timescales; thus, long-term dynamics allows one to constrain the orbital architectures of many closely packed multi-planet systems. A central challenge in such efforts is the large computational cost of N-body simulations, which preclude a full survey of the high-dimensional parameter space of orbital architectures allowed by observations. I will present our recent successes in training machine learning models capable of reliably predicting orbital stability a million times faster than N-body simulations. By engineering dynamically relevant features that we feed to a gradient-boosted decision tree algorithm (XGBoost), we are able to achieve a precision and recall of 90% on a holdout test set of N-body simulations. This opens a wide discovery space for characterizing new exoplanet discoveries and for elucidating how orbital architectures evolve through time as the next generation of spaceborne exoplanet surveys prepare for launch this year.

Closeup view of the Orbiter Discovery as it is suspended ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Close-up view of the Orbiter Discovery as it is suspended vertically by the hoist in the transfer aisle of the Vehicle Assembly Building at Kennedy Space Center. This view is a detail of the starboard wing of the orbiter. Note the Reinforced Carbon-Carbon panels on the leading edge of the wing, the elevons and the elevon seal panels on the wing's trailing edge. - Space Transportation System, Orbiter Discovery (OV-103), Lyndon B. Johnson Space Center, 2101 NASA Parkway, Houston, Harris County, TX

Station Crew Member Discusses Life in Space with Media

NASA Image and Video Library

2018-01-18

Aboard the International Space Station, Expedition 54 Flight Engineer Scott Tingle of NASA discussed life and research on the orbital complex during an in-flight interview session Jan. 18 with the ABC Digital Network and Space.com.

Gidzenko in Service Module with laptop computers

NASA Image and Video Library

2001-03-30

ISS-01-E-5070 (December 2000) --- Astronaut Yuri P. Gidzenko, Expedition One Soyuz commander, works with computers in the Zvezda or Service Module aboard the Earth-orbiting International Space Station (ISS). The picture was taken with a digital still camera.

Recovery of Images from the AMOS ELSI Data for STS-33

DTIC Science & Technology

1990-04-19

ore recorded on tape in both video and digital formats. The ELSI \\-. used on thrce passes, orbits 21, 37, and 67 on 24,2S, and 27 November. These data...November, in video fontit, were hin&narried to Gcopih)sics labontory (0L) :t the beginning or December 1989; tli cl.ified data, in digital formn.t, were...are also sampled and reconverted to maulog form, in a stanicrd viko format, for display on a video monitor and recording on videotape. 3. TAPE FORMAT

The Dynamics of Objects in the Inner Edgeworth Kuiper Belt

NASA Astrophysics Data System (ADS)

Jones, Daniel C.; Williams, Iwan P.; Melita, Mario D.

2005-12-01

Objects in 3:2 mean motion resonance with Neptune are protected from close encounters with Neptune by the resonance. Bodies in orbits with semi-major axis between 39.5 and about 42 AU are not protected by the resonance; indeed due to overlapping secular resonances, the eccentricities of orbits in this region are driven up so that a close encounter with Neptune becomes inevitable. It is thus expected that such orbits are unstable. The list of known Trans-Neptunian objects shows a deficiency in the number of objects in this gap compared to the 43 50 AU region, but the gap is not empty. We numerically integrate models for the initial population in the gap, and also all known objects over the age of the Solar System to determine what fraction can survive. We find that this fraction is significantly less than the ratio of the population in the gap to that in the main belt, suggesting that some mechanism must exist to introduce new members into the gap. By looking at the evolution of the test body orbits, we also determine the manner in which they are lost. Though all have close encounters with Neptune, in most cases this does not lead to ejection from the Solar System, but rather to a reduced perihelion distance causing close encounters with some or all of the other giant planets before being eventually lost from the system, with Saturn appearing to be the cause of the ejection of most of the objects.

The Role of After-School Digital Media Clubs in Closing Participation Gaps and Expanding Social Networks

ERIC Educational Resources Information Center

Vickery, Jacqueline Ryan

2014-01-01

This article considers how after-school digital media clubs, as an example of informal learning, can provide meaningful opportunities for youth to participate in the creation of interest-driven learning ecologies through media production. Ethnographic research was conducted in two after-school digital media clubs at a large, ethnically diverse,…

Free Enterprise: Contributions of the Approach and Landing Test (ALT) Program to the Development of the Space Shuttle Orbiter

NASA Technical Reports Server (NTRS)

Merlin, Peter W.

2006-01-01

The space shuttle orbiter was the first spacecraft designed with the aerodynamic characteristics and in-atmosphere handling qualities of a conventional airplane. In order to evaluate the orbiter's flight control systems and subsonic handling characteristics, a series of flight tests were undertaken at NASA Dryden Flight Research Center in 1977. A modified Boeing 747 Shuttle Carrier Aircraft carried the Enterprise, a prototype orbiter, during eight captive tests to determine how well the two vehicles flew together and to test some of the orbiter s systems. The free-flight phase of the ALT program allowed shuttle pilots to explore the orbiter's low-speed flight and landing characteristics. The Enterprise provided realistic, in-flight simulations of how subsequent space shuttles would be flown at the end of an orbital mission. The fifth free flight, with the Enterprise landing on a concrete runway for the first time, revealed a problem with the space shuttle flight control system that made it susceptible to pilot-induced oscillation, a potentially dangerous control problem. Further research using various aircraft, particularly NASA Dryden's F-8 Digital-Fly-By-Wire testbed, led to correction of the problem before the first Orbital Test Flight.

Space station assembly/servicing capabilities

NASA Technical Reports Server (NTRS)

Joyce, Joseph

1986-01-01

The aim is to place a permanently manned space station on-orbit around the Earth, which is international in scope. The program is nearing the close of the system definition and preliminary design phase. The first shuttle launch for space station assembly on-orbit is estimated for January 1993. Topics perceived to be important to on-orbit assembly and servicing are discussed. This presentation is represented by charts.

Closeup view of the aft flight deck of the Orbiter ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Close-up view of the aft flight deck of the Orbiter Discovery looking at the aft center control panels A6, A7, A8, A12, A13, A14, A16 and A17. This View was taken at Kennedy Space Center. - Space Transportation System, Orbiter Discovery (OV-103), Lyndon B. Johnson Space Center, 2101 NASA Parkway, Houston, Harris County, TX

Closeup view of the upper exterior of the forward fuselage ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Close-up view of the upper exterior of the forward fuselage of the Orbiter Discovery in the Orbiter Processing Facility at NASA's Kennedy Space Center. The view show a detail of the flight deck windows with protective covers installed to protect the window surfaces during processing. - Space Transportation System, Orbiter Discovery (OV-103), Lyndon B. Johnson Space Center, 2101 NASA Parkway, Houston, Harris County, TX

Image based SAR product simulation for analysis

NASA Technical Reports Server (NTRS)

Domik, G.; Leberl, F.

1987-01-01

SAR product simulation serves to predict SAR image gray values for various flight paths. Input typically consists of a digital elevation model and backscatter curves. A new method is described of product simulation that employs also a real SAR input image for image simulation. This can be denoted as 'image-based simulation'. Different methods to perform this SAR prediction are presented and advantages and disadvantages discussed. Ascending and descending orbit images from NASA's SIR-B experiment were used for verification of the concept: input images from ascending orbits were converted into images from a descending orbit; the results are compared to the available real imagery to verify that the prediction technique produces meaningful image data.

Analysis of separation of the space shuttle orbiter from a large transport airplane

NASA Technical Reports Server (NTRS)

Wilhite, A. W.

1977-01-01

The feasibility of safely separating the space shuttle orbiter (140A/B) from the top of a large carrier vehicle (the C-5 airplane) at subsonic speeds was investigated. The longitudinal equations of motion for both vehicles were numerically integrated using a digital computer program which incorporates experimentally derived interference aerodynamic data to analyze the separation maneuver for various initial conditions. Separation of the space shuttle orbiter from a carrier vehicle was feasible for a range of dynamic-pressure and flight-path-angle conditions. By using an autopilot, the vehicle attitudes were held constant which ensured separation. Carrier-vehicle engine thrust, landing gear, and spoilers provide some flexibility in the separation maneuver.

Why Are Hot Jupiters So Lonely?

NASA Astrophysics Data System (ADS)

Kohler, Susanna

2017-10-01

Jupiter-like planets with blisteringly close-in orbits are generally friendless, with no nearbyplanets transiting along with them. Giant planets with orbits a little further out, on the other hand, often have at least one companion. A new study examines the cause of hot Jupiters loneliness.Forming Close-In GiantsArtists impression of a planet forming within a protoplanetary disk. [NAOJ]Though weve studied close-in giant planets for decades now, we still dont fully understand how these objects form and evolve. Jupiter-like giant planets could form in situ next to their host stars, or they could form further out in the system beyond the ice line and then migrate inwards. And if they do migrate, this migration could occur early, while the protoplanetary disk still exists, or long after, via excitation of large eccentricities.We can try to resolve this mystery by examining the statistics of the close-in giant planets weve observed, but this often raises more questions than it answers. A prime example: the properties of close-in giants that have close-in companion planets orbiting in the same plane (i.e., co-transiting).About half of warm Jupiters Jupiter-like planets with periods of 1030 days appear to have close-in, co-transiting companions. In contrast, almost no hot Jupiters Jupiter-like planets with periods of less than 10 days have such companions. What causes this dichotomy?Schematic of the authors model, in which the close-in giant (m1) encounters a resonance with its host star, causing the orbit of the exterior companion (m2) to become tilted. [Spalding Batygin 2017]Friendless Hot JupitersWhile traditional models have argued that the two types of planets form via different pathways warm Jupiters form in situ, or else migrate inward early and smoothly, whereas hot Jupiters migrate inward late and violently, losing their companions in the process a new study casts doubt on this picture.Two scientists from the California Institute of Technology, Christopher Spalding and Konstantin Batygin, propose an alternative picture in which both types of planets form through identical pathways. Instead, they argue, a hot Jupiters apparent loneliness arises over time through interactions with its host star.Stellar Interactions Impact CompanionsSemimajor axis for the outer companion (a2) vs that of the close-in giant planet (a1) at three different system ages. Outer companions within the shaded region will not encounter the resonance investigated by the authors, instead remaining coplanar with the inner giant. For this reason, warm Jupiters will have evident companions whereas hot Jupiters will not. [Spalding Batygin 2017]Whether giant planets form in situ near their hosts or migrate inward, they can still have close-in, co-transiting companions outside of their orbit shortly after their birth, Spalding and Batygin argue. But after the disk in which they were born dissipates, the orbits of their companions may be altered.The authors demonstrate that because hot Jupiters are so close to their hosts, these giants eventually encounter a resonance with their stellar hosts quadrupole moment, which arises because rotating stars arent perfectly spherical. This resonance tilts the orbits of the hot Jupiters outer, lower-mass companions, rendering the companions undetectable in transit surveys.Warm Jupiters, on the other hand, are located just far enough away from their hosts to avoid feeling the effects of this resonance which allows them to keep their outer companions in the same plane.Based on their model, Spalding and Batygin make direct predictions for the systems they expect to be observed in large upcoming surveys like the Transiting Exoplanet Survey Satellite (TESS) which means we should soon have a sense of whether their picture is correct. If it is, it will confirm that the non-sphericity of stars can have significant impact on the dynamics and architecture of exoplanetary systems.CitationChristopher Spalding and Konstantin Batygin 2017 AJ 154 93. doi:10.3847/1538-3881/aa8174

The Fate of Close-in Planets: Tidal or Magnetic Migration?

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

Strugarek, A.; Bolmont, E.; Mathis, S.

Planets in close-in orbits interact magnetically and tidally with their host stars. These interactions lead to a net torque that makes close-in planets migrate inward or outward depending on their orbital distance. We systematically compare the strength of magnetic and tidal torques for typical observed star–planet systems (T-Tauri and hot Jupiter, M-dwarf and Earth-like planet, K star and hot Jupiter) based on state-of-the-art scaling laws. We find that depending on the characteristics of the system, tidal or magnetic effects can dominate. For very close-in planets, we find that both torques can make a planet migrate on a timescale as smallmore » as 10–100 thousands of years. Both effects thus have to be taken into account when predicting the evolution of compact systems.« less

Dancing to CHANGA: a self-consistent prediction for close SMBH pair formation time-scales following galaxy mergers

NASA Astrophysics Data System (ADS)

Tremmel, M.; Governato, F.; Volonteri, M.; Quinn, T. R.; Pontzen, A.

2018-04-01

We present the first self-consistent prediction for the distribution of formation time-scales for close supermassive black hole (SMBH) pairs following galaxy mergers. Using ROMULUS25, the first large-scale cosmological simulation to accurately track the orbital evolution of SMBHs within their host galaxies down to sub-kpc scales, we predict an average formation rate density of close SMBH pairs of 0.013 cMpc-3 Gyr-1. We find that it is relatively rare for galaxy mergers to result in the formation of close SMBH pairs with sub-kpc separation and those that do form are often the result of Gyr of orbital evolution following the galaxy merger. The likelihood and time-scale to form a close SMBH pair depends strongly on the mass ratio of the merging galaxies, as well as the presence of dense stellar cores. Low stellar mass ratio mergers with galaxies that lack a dense stellar core are more likely to become tidally disrupted and deposit their SMBH at large radii without any stellar core to aid in their orbital decay, resulting in a population of long-lived `wandering' SMBHs. Conversely, SMBHs in galaxies that remain embedded within a stellar core form close pairs in much shorter time-scales on average. This time-scale is a crucial, though often ignored or very simplified, ingredient to models predicting SMBH mergers rates and the connection between SMBH and star formation activity.

Hawk Eyes I: Diurnal Raptors Differ in Visual Fields and Degree of Eye Movement

PubMed Central

O'Rourke, Colleen T.; Hall, Margaret I.; Pitlik, Todd; Fernández-Juricic, Esteban

2010-01-01

Background Different strategies to search and detect prey may place specific demands on sensory modalities. We studied visual field configuration, degree of eye movement, and orbit orientation in three diurnal raptors belonging to the Accipitridae and Falconidae families. Methodology/Principal Findings We used an ophthalmoscopic reflex technique and an integrated 3D digitizer system. We found inter-specific variation in visual field configuration and degree of eye movement, but not in orbit orientation. Red-tailed Hawks have relatively small binocular areas (∼33°) and wide blind areas (∼82°), but intermediate degree of eye movement (∼5°), which underscores the importance of lateral vision rather than binocular vision to scan for distant prey in open areas. Cooper's Hawks' have relatively wide binocular fields (∼36°), small blind areas (∼60°), and high degree of eye movement (∼8°), which may increase visual coverage and enhance prey detection in closed habitats. Additionally, we found that Cooper's Hawks can visually inspect the items held in the tip of the bill, which may facilitate food handling. American Kestrels have intermediate-sized binocular and lateral areas that may be used in prey detection at different distances through stereopsis and motion parallax; whereas the low degree eye movement (∼1°) may help stabilize the image when hovering above prey before an attack. Conclusions We conclude that: (a) there are between-species differences in visual field configuration in these diurnal raptors; (b) these differences are consistent with prey searching strategies and degree of visual obstruction in the environment (e.g., open and closed habitats); (c) variations in the degree of eye movement between species appear associated with foraging strategies; and (d) the size of the binocular and blind areas in hawks can vary substantially due to eye movements. Inter-specific variation in visual fields and eye movements can influence behavioral strategies to visually search for and track prey while perching. PMID:20877645

Hawk eyes I: diurnal raptors differ in visual fields and degree of eye movement.

PubMed

O'Rourke, Colleen T; Hall, Margaret I; Pitlik, Todd; Fernández-Juricic, Esteban

2010-09-22

Different strategies to search and detect prey may place specific demands on sensory modalities. We studied visual field configuration, degree of eye movement, and orbit orientation in three diurnal raptors belonging to the Accipitridae and Falconidae families. We used an ophthalmoscopic reflex technique and an integrated 3D digitizer system. We found inter-specific variation in visual field configuration and degree of eye movement, but not in orbit orientation. Red-tailed Hawks have relatively small binocular areas (∼33°) and wide blind areas (∼82°), but intermediate degree of eye movement (∼5°), which underscores the importance of lateral vision rather than binocular vision to scan for distant prey in open areas. Cooper's Hawks' have relatively wide binocular fields (∼36°), small blind areas (∼60°), and high degree of eye movement (∼8°), which may increase visual coverage and enhance prey detection in closed habitats. Additionally, we found that Cooper's Hawks can visually inspect the items held in the tip of the bill, which may facilitate food handling. American Kestrels have intermediate-sized binocular and lateral areas that may be used in prey detection at different distances through stereopsis and motion parallax; whereas the low degree eye movement (∼1°) may help stabilize the image when hovering above prey before an attack. We conclude that: (a) there are between-species differences in visual field configuration in these diurnal raptors; (b) these differences are consistent with prey searching strategies and degree of visual obstruction in the environment (e.g., open and closed habitats); (c) variations in the degree of eye movement between species appear associated with foraging strategies; and (d) the size of the binocular and blind areas in hawks can vary substantially due to eye movements. Inter-specific variation in visual fields and eye movements can influence behavioral strategies to visually search for and track prey while perching.

Cassini's Ring Grazing and Grand Finale Orbits: Topping Off an Awesome Mission

NASA Astrophysics Data System (ADS)

Edgington, Scott; Spilker, Linda; Coustenis, Athena

2017-04-01

The Cassini-Huygens mission, a joint collaboration between NASA, ESA, and the Italian Space Agency, is in its last year of operations after nearly 13 years in orbit around Saturn. Cassini will send back its final bits of unique data on September 15th, 2017 as it plunges into Saturn's atmosphere, vaporizing and satisfying planetary protection requirements. Before that time Cassini will continue its legacy of exploration and discovery in 2017 and return unique science data provided by orbits taking the spacecraft into unexplored regions near Saturn and its rings. From the new vantage points, Cassini will continue to study seasonal and temporal changes in the system as northern summer solstice approaches. With the exception of one remaining targeted Titan flyby, all of Cassini's close icy satellite flybys, including those of Enceladus, are now completed. In November 2016, Cassini transitioned to a series of orbits with peripases just outside Saturn's F ring. These 20 orbits include close flybys of some tiny ring moons and excellent views of the F ring and Saturn's outer A ring. The 126th and final close flyby of Titan will propel Cassini across Saturn's main rings and into its Grand Finale series of orbits. Cassini's Grand Finale, starting in April 2017, is comprised of 22 orbits at an inclination of 63 degrees. Cassini will repeatedly dive between Saturn's innermost rings and upper atmosphere providing insights into fundamental questions unattainable during the rest of the mission. Cassini will be the first spacecraft to explore this region. These close orbits provide the highest resolution observations of both the rings and Saturn, and direct in-situ sampling of the ring particles, composition, plasma, Saturn's exosphere and the innermost radiation belts. Saturn's gravitational field will be measured to unprecedented accuracy, providing information on the interior structure of the planet, winds in the outer layers of Saturn's atmosphere, and the mass distribution in the rings. Probing the magnetic field will give insight into the nature of the magnetic dynamo, telling us: why the magnetic field is weak; why it exhibits little, if any, axial tilt; and the true rotation rate of the planet. The ion and neutral mass spectrometer will sniff the exosphere and upper atmosphere for molecules that escape the atmosphere itself and water-based molecules originating from the rings. The cosmic dust analyzer will sample the composition of particles from different parts of the main rings. Until the execution of these final orbits, the answers to such new questions will remain mysteries. The science highlights of Cassini's Grand Finale orbits will be discussed. This work was carried out in part at the Jet Propulsion Laboratory, California Institute of Technology, under contract with NASA. Copyright 2017 California Institute of Technology. Government sponsorship is acknowledged.

A flexible, open, decentralized system for digital pathology networks.

PubMed

Schuler, Robert; Smith, David E; Kumaraguruparan, Gowri; Chervenak, Ann; Lewis, Anne D; Hyde, Dallas M; Kesselman, Carl

2012-01-01

High-resolution digital imaging is enabling digital archiving and sharing of digitized microscopy slides and new methods for digital pathology. Collaborative research centers, outsourced medical services, and multi-site organizations stand to benefit from sharing pathology data in a digital pathology network. Yet significant technological challenges remain due to the large size and volume of digitized whole slide images. While information systems do exist for managing local pathology laboratories, they tend to be oriented toward narrow clinical use cases or offer closed ecosystems around proprietary formats. Few solutions exist for networking digital pathology operations. Here we present a system architecture and implementation of a digital pathology network and share results from a production system that federates major research centers.

A Flexible, Open, Decentralized System for Digital Pathology Networks

PubMed Central

SMITH, David E.; KUMARAGURUPARAN, Gowri; CHERVENAK, Ann; LEWIS, Anne D.; HYDE, Dallas M.; KESSELMAN, Carl

2014-01-01

High-resolution digital imaging is enabling digital archiving and sharing of digitized microscopy slides and new methods for digital pathology. Collaborative research centers, outsourced medical services, and multi-site organizations stand to benefit from sharing pathology data in a digital pathology network. Yet significant technological challenges remain due to the large size and volume of digitized whole slide images. While information systems do exist for managing local pathology laboratories, they tend to be oriented toward narrow clinical use cases or offer closed ecosystems around proprietary formats. Few solutions exist for networking digital pathology operations. Here we present a system architecture and implementation of a digital pathology network and share results from a production system that federates major research centers. PMID:22941985

Spaceborne Autonomous and Ground Based Relative Orbit Control for the TerraSAR-X/TanDEM-X Formation

NASA Technical Reports Server (NTRS)

Ardaens, J. S.; D'Amico, S.; Kazeminejad, B.; Montenbruck, O.; Gill, E.

2007-01-01

TerraSAR-X (TSX) and TanDEM-X (TDX) are two advanced synthetic aperture radar (SAR) satellites flying in formation. SAR interferometry allows a high resolution imaging of the Earth by processing SAR images obtained from two slightly different orbits. TSX operates as a repeat-pass interferometer in the first phase of its lifetime and will be supplemented after two years by TDX in order to produce digital elevation models (DEM) with unprecedented accuracy. Such a flying formation makes indeed possible a simultaneous interferometric data acquisition characterized by highly flexible baselines with range of variations between a few hundreds meters and several kilometers [1]. TSX has been successfully launched on the 15th of June, 2007. TDX is expected to be launched on the 31st of May, 2009. A safe and robust maintenance of the formation is based on the concept of relative eccentricity/inclination (e/i) vector separation whose efficiency has already been demonstrated during the Gravity Recovery and Climate Experiment (GRACE) [2]. Here, the satellite relative motion is parameterized by mean of relative orbit elements and the key idea is to align the relative eccentricity and inclination vectors to minimize the hazard of a collision. Previous studies have already shown the pertinence of this concept and have described the way of controlling the formation using an impulsive deterministic control law [3]. Despite the completely different relative orbit control requirements, the same approach can be applied to the TSX/TDX formation. The task of TDX is to maintain the close formation configuration by actively controlling its relative motion with respect to TSX, the leader of the formation. TDX must replicate the absolute orbit keeping maneuvers executed by TSX and also compensate the natural deviation of the relative e/i vectors. In fact the relative orbital elements of the formation tend to drift because of the secular non-keplerian perturbations acting on both satellites. The goal of the ground segment is thus to regularly correct this configuration by performing small orbit correction maneuvers on TDX. The ground station contacts are limited due to the geographic position of the station and the costs for contact time. Only with a polar ground station a contact visibility is possible every orbit for LEO satellites. TSX and TDX use only the Weilheim ground station (in the southern part of Germany) during routine operations. This station allows two scheduled contact per day for the nominal orbit configuration, meaning that the satellite conditions can be checked with an interval of 12 hours. While this limitation is usually not critical for single satellite operations, the visibility constraints drive the achievable orbit control accuracy for a LEO formation if a ground based approach is chosen. Along-track position uncertainties and maneuver execution errors affect the relative motion and can be compensated only after a ground station contact.

A digital wireless system for closed-loop inhibition of nociceptive signals

NASA Astrophysics Data System (ADS)

Zuo, Chao; Yang, Xiaofei; Wang, Yang; Hagains, Christopher E.; Li, Ai-Ling; Peng, Yuan B.; Chiao, J.-C.

2012-10-01

Neurostimulation of the spinal cord or brain has been used to inhibit nociceptive signals in pain management applications. Nevertheless, most of the current neurostimulation models are based on open-loop system designs. There is a lack of closed-loop systems for neurostimulation in research with small freely-moving animals and in future clinical applications. Based on our previously developed analog wireless system for closed-loop neurostimulation, a digital wireless system with real-time feedback between recorder and stimulator modules has been developed to achieve multi-channel communication. The wireless system includes a wearable recording module, a wearable stimulation module and a transceiver connected to a computer for real-time and off-line data processing, display and storage. To validate our system, wide dynamic range neurons in the spinal cord dorsal horn have been recorded from anesthetized rats in response to graded mechanical stimuli (brush, pressure and pinch) applied in the hind paw. The identified nociceptive signals were used to automatically trigger electrical stimulation at the periaqueductal gray in real time to inhibit their own activities by the closed-loop design. Our digital wireless closed-loop system has provided a simplified and efficient method for further study of pain processing in freely-moving animals and potential clinical application in patients. Groups 1, 2 and 3 contributed equally to this project.

RHIC BPM system average orbit calculations

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

Michnoff,R.; Cerniglia, P.; Degen, C.

2009-05-04

RHIC beam position monitor (BPM) system average orbit was originally calculated by averaging positions of 10000 consecutive turns for a single selected bunch. Known perturbations in RHIC particle trajectories, with multiple frequencies around 10 Hz, contribute to observed average orbit fluctuations. In 2006, the number of turns for average orbit calculations was made programmable; this was used to explore averaging over single periods near 10 Hz. Although this has provided an average orbit signal quality improvement, an average over many periods would further improve the accuracy of the measured closed orbit. A new continuous average orbit calculation was developed justmore » prior to the 2009 RHIC run and was made operational in March 2009. This paper discusses the new algorithm and performance with beam.« less

A Dynamical Systems Approach to the Design of the Science Orbit Around Europa

NASA Technical Reports Server (NTRS)

Gomez, Gerard; Lara, Martin; Russell, Ryan P.

2006-01-01

The science orbit for a future mission to Europa requires low eccentricity, low altitude, and high inclination. However, high inclination orbits around planetary satellites are unstable due to third-body perturbations. Without control, the orbiter impacts Europa after few weeks. To minimize control, a tour over the stable-unstable, averaged manifolds of unstable frozen orbits has been suggested. We proceed with the unaveraged equations and study the manifolds of unstable orbits that are periodic in a rotating frame attached to Europa. Massive numerical computation helps in understanding the unstable dynamics close to Europa, and, thus, in selecting long lifetime high inclination orbits. A final test of a selected set of initial conditions on a high fidelity, ephemeris model, validate the results.

Horowitz checks flight notes at the commander's station

NASA Image and Video Library

2001-08-10

STS105-E-5002 (10 August 2001) --- Astronaut Scott J. Horowitz, STS-105 commander, checks flight notes at the commander's station on the flight deck of the Earth-orbiting Space Shuttle Discovery. The image was recorded with a digital still camera.

Horowitz checks flight notes at the commander's station

NASA Image and Video Library

2001-08-10

STS105-E-5001 (10 August 2001) --- Astronaut Scott J. Horowitz, STS-105 commander, checks flight notes at the commander's station on the flight deck of the Earth-orbiting Space Shuttle Discovery. The image was recorded with a digital still camera.

Space Shuttle orbit determination using empirical force modeling of attitude maneuvers for the German MOMS-02/D2 mission

NASA Technical Reports Server (NTRS)

Vonbraun, C.; Reigber, Christoph

1994-01-01

In the spring of 1993, the MOMS-02 (modular Optoelectronic Multispectral Scanner) camera, as part of the second German Spacelab mission aboard STS-55, successfully took digital threefold stereo images of the surface of the Earth. While the mission is experimental in nature, its primary goals are to produce high quality maps and three-dimensional digital terrain models of the Earth's surface. Considerable improvement in the quality of the terrain model can be attained if information about the position and attitude of the camera is included during the adjustment of the image data. One of the primary sources of error in the Shuttle's position is due to the significant attitude maneuvers conducted during the course of the mission. Various arcs, using actual Tracking and Data Relay Satellite (TDRSS) Doppler data of STS-55, were processed to determine how effectively empirical force modeling could be used to solve for the radial, transverse, and normal components of the orbit perturbations caused by these routine maneuvers. Results are presented in terms of overlap-orbit differences in the three components. Comparisons of these differences, before and after the maneuvers are estimated, show that the quality of an orbit can be greatly enhanced with this technique, even if several maneuvers are present. Finally, a discussion is made of some of the difficulties encountered with this approach, and some ideas for future studies are presented.

3D measurement by digital photogrammetry

NASA Astrophysics Data System (ADS)

Schneider, Carl T.

1993-12-01

Photogrammetry is well known in geodetic surveys as aerial photogrammetry or close range applications as architectural photogrammetry. The photogrammetric methods and algorithms combined with digital cameras and digital image processing methods are now introduced for industrial applications as automation and quality control. The presented paper will describe the photogrammetric and digital image processing algorithms and the calibration methods. These algorithms and methods were demonstrated with application examples. These applications are a digital photogrammetric workstation as a mobil multi purpose 3D measuring tool and a tube measuring system as an example for a single purpose tool.

The Dynamical History of Chariklo and Its Rings

NASA Astrophysics Data System (ADS)

Wood, Jeremy; Horner, Jonti; Hinse, Tobias C.; Marsden, Stephen C.

2017-06-01

Chariklo is the only small solar system body confirmed to have rings. Given the instability of its orbit, the presence of rings is surprising, and their origin remains poorly understood. In this work, we study the dynamical history of the Chariklo system by integrating almost 36,000 Chariklo clones backward in time for 1 Gyr under the influence of the Sun and the four giant planets. By recording all close encounters between the clones and planets, we investigate the likelihood that Chariklo’s rings could have survived since its capture to the Centaur population. Our results reveal that Chariklo’s orbit occupies a region of stable chaos, resulting in its orbit being marginally more stable than those of the other Centaurs. Despite this, we find that it was most likely captured to the Centaur population within the last 20 Myr, and that its orbital evolution has been continually punctuated by regular close encounters with the giant planets. The great majority (>99%) of those encounters within 1 Hill radius of the planet have only a small effect on the rings. We conclude that close encounters with giant planets have not had a significant effect on the ring structure. Encounters within the Roche limit of the giant planets are rare, making ring creation through tidal disruption unlikely.

The Dynamical History of Chariklo and Its Rings

NASA Astrophysics Data System (ADS)

Wood, Jeremy R.; Horner, Jonti; Hinse, Tobias; Marsden, Stephen

2017-10-01

Chariklo is the only small Solar system body confirmed to have rings. Given the instability of its orbit, the presence of rings is surprising, and their origin remains poorly understood. In this work, we study the dynamical history of the Chariklo system by integrating almost 36,000 Chariklo clones backwards in time for one Gyr under the influence of the Sun and the four giant planets. By recording all close encounters between the clones and planets, we investigate the likelihood that Chariklo's rings could have survived since its capture to the Centaur population. Our results reveal that Chariklo's orbit occupies a region of stable chaos, resulting in its orbit being marginally more stable than those of the other Centaurs. Despite this, we find that it was most likely captured to the Centaur population within the last 20 Myr, and that its orbital evolution has been continually punctuated by regular close encounters with the giant planets. The great majority (> 99%) of those encounters within one Hill radius of the planet have only a small effect on the rings. We conclude that close encounters with giant planets have not had a significant effect on the ring structure. Encounters within the Roche limit of the giant planets are rare, making ring creation through tidal disruption unlikely.

The Dynamical History of Chariklo and Its Rings

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

Wood, Jeremy; Horner, Jonti; Marsden, Stephen C.

Chariklo is the only small solar system body confirmed to have rings. Given the instability of its orbit, the presence of rings is surprising, and their origin remains poorly understood. In this work, we study the dynamical history of the Chariklo system by integrating almost 36,000 Chariklo clones backward in time for 1 Gyr under the influence of the Sun and the four giant planets. By recording all close encounters between the clones and planets, we investigate the likelihood that Chariklo’s rings could have survived since its capture to the Centaur population. Our results reveal that Chariklo’s orbit occupies amore » region of stable chaos, resulting in its orbit being marginally more stable than those of the other Centaurs. Despite this, we find that it was most likely captured to the Centaur population within the last 20 Myr, and that its orbital evolution has been continually punctuated by regular close encounters with the giant planets. The great majority (>99%) of those encounters within 1 Hill radius of the planet have only a small effect on the rings. We conclude that close encounters with giant planets have not had a significant effect on the ring structure. Encounters within the Roche limit of the giant planets are rare, making ring creation through tidal disruption unlikely.« less

Secular resonances between bodies on close orbits II: prograde and retrograde orbits for irregular satellites

NASA Astrophysics Data System (ADS)

Li, Daohai; Christou, Apostolos A.

2017-09-01

In extending the analysis of the four secular resonances between close orbits in Li and Christou (Celest Mech Dyn Astron 125:133-160, 2016) (Paper I), we generalise the semianalytical model so that it applies to both prograde and retrograde orbits with a one-to-one map between the resonances in the two regimes. We propose the general form of the critical angle to be a linear combination of apsidal and nodal differences between the two orbits b_1 Δ π + b_2 Δ Ω, forming a collection of secular resonances in which the ones studied in Paper I are among the strongest. Test of the model in the orbital vicinity of massive satellites with physical and orbital parameters similar to those of the irregular satellites Himalia at Jupiter and Phoebe at Saturn shows that {>}20 and {>}40% of phase space is affected by these resonances, respectively. The survivability of the resonances is confirmed using numerical integration of the full Newtonian equations of motion. We observe that the lowest order resonances with b_1+|b_2|≤ 3 persist, while even higher-order resonances, up to b_1+|b_2|≥ 7, survive. Depending on the mass, between 10 and 60% of the integrated test particles are captured in these secular resonances, in agreement with the phase space analysis in the semianalytical model.

Tatooines Future: The Eccentric Response of Keplers Circumbinary Planets to Common-Envelope Evolution of their Host Stars

NASA Technical Reports Server (NTRS)

Kostov, Veselin B.; Moore, Keavin; Tamayo, Daniel; Jayawardhana, Ray; Rinehart, Stephen A.

2016-01-01

Inspired by the recent Kepler discoveries of circumbinary planets orbiting nine close binary stars, we explore the fate of the former as the latter evolve off the main sequence. We combine binary star evolution models with dynamical simulations to study the orbital evolution of these planets as their hosts undergo common-envelope stages, losing in the process a tremendous amount of mass on dynamical timescales. Five of the systems experience at least one Roche-lobe overflow and common-envelope stages (Kepler-1647 experiences three), and the binary stars either shrink to very short orbits or coalesce; two systems trigger a double-degenerate supernova explosion. Kepler's circumbinary planets predominantly remain gravitationally bound at the end of the common-envelope phase, migrate to larger orbits, and may gain significant eccentricity; their orbital expansion can be more than an order of magnitude and can occur over the course of a single planetary orbit. The orbits these planets can reach are qualitatively consistent with those of the currently known post-common-envelope, eclipse-time variations circumbinary candidates. Our results also show that circumbinary planets can experience both modes of orbital expansion (adiabatic and non-adiabatic) if their host binaries undergo more than one common-envelope stage; multiplanet circumbinary systems like Kepler-47 can experience both modes during the same common-envelope stage. Additionally, unlike Mercury orbiting the Sun, a circumbinary planet with the same semi-major axis can survive the common envelope evolution of a close binary star with a total mass of 1 Solar Mass.

PUMPING THE ECCENTRICITY OF EXOPLANETS BY TIDAL EFFECT

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

Correia, Alexandre C. M.; Boue, Gwenaeel; Laskar, Jacques, E-mail: correia@ua.pt

2012-01-10

Planets close to their host stars are believed to undergo significant tidal interactions, leading to a progressive damping of the orbital eccentricity. Here we show that when the orbit of the planet is excited by an outer companion, tidal effects combined with gravitational interactions may give rise to a secular increasing drift on the eccentricity. As long as this secular drift counterbalances the damping effect, the eccentricity can increase to high values. This mechanism may explain why some of the moderate close-in exoplanets are observed with substantial eccentricity values.

MAGNETIC GAMES BETWEEN A PLANET AND ITS HOST STAR: THE KEY ROLE OF TOPOLOGY

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

Strugarek, A.; Brun, A. S.; Réville, V.

Magnetic interactions between a star and a close-in planet are postulated to be a source of enhanced emissions and to play a role in the secular evolution of the orbital system. Close-in planets generally orbit in the sub-alfvénic region of the stellar wind, which leads to efficient transfers of energy and angular momentum between the star and the planet. We model the magnetic interactions occurring in close-in star–planet systems with three-dimensional, global, compressible magnetohydrodynamic numerical simulations of a planet orbiting in a self-consistent stellar wind. We focus on the cases of magnetized planets and explore three representative magnetic configurations. Themore » Poynting flux originating from the magnetic interactions is an energy source for enhanced emissions in star–planet systems. Our results suggest a simple geometrical explanation for ubiquitous on/off enhanced emissions associated with close-in planets, and confirm that the Poynting fluxes can reach powers of the order of 10{sup 19} W. Close-in planets are also shown to migrate due to magnetic torques for sufficiently strong stellar wind magnetic fields. The topology of the interaction significantly modifies the shape of the magnetic obstacle that leads to magnetic torques. As a consequence, the torques can vary by at least an order of magnitude as the magnetic topology of the interaction varies.« less

Magnetic Games between a Planet and Its Host Star: The Key Role of Topology

NASA Astrophysics Data System (ADS)

Strugarek, A.; Brun, A. S.; Matt, S. P.; Réville, V.

2015-12-01

Magnetic interactions between a star and a close-in planet are postulated to be a source of enhanced emissions and to play a role in the secular evolution of the orbital system. Close-in planets generally orbit in the sub-alfvénic region of the stellar wind, which leads to efficient transfers of energy and angular momentum between the star and the planet. We model the magnetic interactions occurring in close-in star-planet systems with three-dimensional, global, compressible magnetohydrodynamic numerical simulations of a planet orbiting in a self-consistent stellar wind. We focus on the cases of magnetized planets and explore three representative magnetic configurations. The Poynting flux originating from the magnetic interactions is an energy source for enhanced emissions in star-planet systems. Our results suggest a simple geometrical explanation for ubiquitous on/off enhanced emissions associated with close-in planets, and confirm that the Poynting fluxes can reach powers of the order of 1019 W. Close-in planets are also shown to migrate due to magnetic torques for sufficiently strong stellar wind magnetic fields. The topology of the interaction significantly modifies the shape of the magnetic obstacle that leads to magnetic torques. As a consequence, the torques can vary by at least an order of magnitude as the magnetic topology of the interaction varies.

Close encounters of a rotating star with planets in parabolic orbits of varying inclination and the formation of hot Jupiters

NASA Astrophysics Data System (ADS)

Ivanov, P. B.; Papaloizou, J. C. B.

2011-10-01

In this paper we extend the theory of close encounters of a giant planet on a parabolic orbit with a central star developed in our previous work (Ivanov and Papaloizou in MNRAS 347:437, 2004; MNRAS 376:682, 2007) to include the effects of tides induced on the central star. Stellar rotation and orbits with arbitrary inclination to the stellar rotation axis are considered. We obtain results both from an analytic treatment that incorporates first order corrections to normal mode frequencies arising from stellar rotation and numerical treatments that are in satisfactory agreement over the parameter space of interest. These results are applied to the initial phase of the tidal circularisation problem. We find that both tides induced in the star and planet can lead to a significant decrease of the orbital semi-major axis for orbits having periastron distances smaller than 5-6 stellar radii with tides in the star being much stronger for retrograde orbits compared to prograde orbits. Assuming that combined action of dynamic and quasi-static tides could lead to the total circularisation of orbits this corresponds to observed periods up to 4-5 days. We use the simple Skumanich law to characterise the rotational history of the star supposing that the star has its rotational period equal to one month at the age of 5 Gyr. The strength of tidal interactions is characterised by circularisation time scale, t ev , which is defined as a typical time scale of evolution of the planet's semi-major axis due to tides. This is considered as a function of orbital period P obs , which the planet obtains after the process of tidal circularisation has been completed. We find that the ratio of the initial circularisation time scales corresponding to prograde and retrograde orbits, respectively, is of order 1.5-2 for a planet of one Jupiter mass having P obs ~ 4 days. The ratio grows with the mass of the planet, being of order five for a five Jupiter mass planet with the same P orb . Note, however, this result might change for more realistic stellar rotation histories. Thus, the effect of stellar rotation may provide a bias in the formation of planetary systems having planets on close orbits around their host stars, as a consequence of planet-planet scattering, which favours systems with retrograde orbits. The results reported in the paper may also be applied to the problem of tidal capture of stars in young stellar clusters.

Concept Design of the Payload Handling Manipulator System. [space shuttle orbiters

NASA Technical Reports Server (NTRS)

1975-01-01

The design, requirements, and interface definition of a remote manipulator system developed to handle orbiter payloads are presented. End effector design, control system concepts, and man-machine engineering are considered along with crew station requirements and closed circuit television system performance requirements.

Building up the spin - orbit alignment of interacting galaxy pairs

NASA Astrophysics Data System (ADS)

Moon, Jun-Sung; Yoon, Suk-Jin

2018-01-01

Galaxies are not just randomly distributed throughout space. Instead, they are in alignment over a wide range of scales from the cosmic web down to a pair of galaxies. Motivated by recent findings that the spin and the orbital angular momentum vectors of galaxy pairs tend to be parallel, we here investigate the spin - orbit orientation in close pairs using the Illustris cosmological simulation. We find that since z ~ 1, the parallel alignment has become progressively stronger with time through repetitive encounters. The pair Interactions are preferentially in prograde at z = 0 (over 5 sigma significance). The prograde fraction at z = 0 is larger for the pairs influenced more heavily by each other during their evolution. We find no correlation between the spin - orbit orientation and the surrounding large-scale structure. Our results favor the scenario in which the alignment in close pairs is caused by tidal interactions later on, rather than the primordial torquing by the large-scale structures.

On the Milankovitch orbital elements for perturbed Keplerian motion

NASA Astrophysics Data System (ADS)

Rosengren, Aaron J.; Scheeres, Daniel J.

2014-03-01

We consider sets of natural vectorial orbital elements of the Milankovitch type for perturbed Keplerian motion. These elements are closely related to the two vectorial first integrals of the unperturbed two-body problem; namely, the angular momentum vector and the Laplace-Runge-Lenz vector. After a detailed historical discussion of the origin and development of such elements, nonsingular equations for the time variations of these sets of elements under perturbations are established, both in Lagrangian and Gaussian form. After averaging, a compact, elegant, and symmetrical form of secular Milankovitch-like equations is obtained, which reminds of the structure of canonical systems of equations in Hamiltonian mechanics. As an application of this vectorial formulation, we analyze the motion of an object orbiting about a planet (idealized as a point mass moving in a heliocentric elliptical orbit) and subject to solar radiation pressure acceleration (obeying an inverse-square law). We show that the corresponding secular problem is integrable and we give an explicit closed-form solution.

Investigation of the McDonnell-Douglas orbiter and booster shuttle models in proximity at Mach numbers 2.0 to 6.0. Volume 7: Proximity data at Mach 4 and 6, interference free and launch vehicle data

NASA Technical Reports Server (NTRS)

Trimmer, L. L.; Love, D. A.; Decker, J. P.; Blackwell, K. L.; Strike, W. T.; Rampy, J. M.

1972-01-01

Aerodynamic data obtained from a space shuttle abort stage separation wind tunnel test are presented. The .00556 scale models of the orbiter and booster configuration were tested in close proximity using dual balances during the time period of April 21 to April 27 1971. Data were obtained for both booster and orbiter over an angle of attack range from -10 to 10 deg for zero degree sideslip angle. The models were tested at several relative incidence angles and separation distances and power conditions. Plug nozzles utilizing air were used to simulate booster and orbiter plumes at various altitudes along a nominal ascent trajectory. Powered conditions were 100, 50, 25 and 0 percent of full power for the orbiter and 100, 50 and 0 percent of full power for the booster. Pitch control effectiveness data were obtained for both booster and orbiter with power on and off. In addition, launch vehicle data with and without booster power were obtained utilizing a single balance in the booster model. Data were also obtained with the booster canard off in close proximity and for the launch configuration.

Angles-only navigation for autonomous orbital rendezvous

NASA Astrophysics Data System (ADS)

Woffinden, David C.

The proposed thesis of this dissertation has both a practical element and theoretical component which aim to answer key questions related to the use of angles-only navigation for autonomous orbital rendezvous. The first and fundamental principle to this work argues that an angles-only navigation filter can determine the relative position and orientation (pose) between two spacecraft to perform the necessary maneuvers and close proximity operations for autonomous orbital rendezvous. Second, the implementation of angles-only navigation for on-orbit applications is looked upon with skeptical eyes because of its perceived limitation of determining the relative range between two vehicles. This assumed, yet little understood subtlety can be formally characterized with a closed-form analytical observability criteria which specifies the necessary and sufficient conditions for determining the relative position and velocity with only angular measurements. With a mathematical expression of the observability criteria, it can be used to (1) identify the orbital rendezvous trajectories and maneuvers that ensure the relative position and velocity are observable for angles-only navigation, (2) quantify the degree or level of observability and (3) compute optimal maneuvers that maximize observability. In summary, the objective of this dissertation is to provide both a practical and theoretical foundation for the advancement of autonomous orbital rendezvous through the use of angles-only navigation.

Using Mean Orbit Period in Mars Reconnaissance Orbiter Maneuver Design

NASA Technical Reports Server (NTRS)

Chung, Min-Kun J.; Menon, Premkumar R.; Wagner, Sean V.; Williams, Jessica L.

2014-01-01

Mars Reconnaissance Orbiter (MRO) has provided communication relays for a number of Mars spacecraft. In 2016 MRO is expected to support a relay for NASA's Interior Exploration using Seismic Investigations, Geodesy and Heat Transport (InSight) spacecraft. In addition, support may be needed by another mission, ESA's ExoMars EDL Demonstrator Module's (EDM), only 21 days after the InSight coverage. The close proximity of these two events presents a unique challenge to a conventional orbit synchronization maneuver where one deterministic maneuver is executed prior to each relay. Since the two events are close together and the difference in required phasing between InSight and EDM may be up to half an orbit (yielding a large execution error), the downtrack timing error can increase rapidly at the EDM encounter. Thus, a new maneuver strategy that does not require a deterministic maneuver in-between the two events (with only a small statistical cleanup) is proposed in the paper. This proposed strategy rests heavily on the stability of the mean orbital period. The ability to search and set the specified mean period is fundamental in the proposed maneuver design as well as in understanding the scope of the problem. The proposed strategy is explained and its result is used to understand and solve the problem in the flight operations environment.

Cardiac arrhythmias and degradation into chaotic behavior prevention using feedback control

NASA Astrophysics Data System (ADS)

Uzelac, Ilija; Sidorov, Veniamin; Wikswo, John; Gray, Richard

2012-02-01

During normal heart rhythm, cardiac cells behave as a set of oscillators with a distribution of phases but with the same frequency. The heart as a dynamical system in a phase space representation can be modeled as a set of oscillators that have closed overlapping orbits with the same period. These orbits are not stable and in the case of disruption of the cardiac rhythm, such as due to premature beats, the system will have a tendency to leave its periodic unstable orbits. If these orbits become attracted to phase singularities, their disruption may lead to chaotic behavior, which appears as a life-threating ventricular fibrillation. By using closed-loop feedback in the form of an adjustable defibrillation shock, any drift from orbits corresponding to the normal rhythm can be corrected by forcing the system to maintain its orbits. The delay through the feedback network coincides with the period of normal heart beats. To implement this approach we developed a 1 kW arbitrary waveform voltage-to-current converter with a 1 kHz bandwidth driven by a photodiode system that records an optical electrocardiogram and provides a feedback signal in real time. Our goal is to determine whether our novel method to defibrillate the heart will require much lower energies than are currently utilized in single shock defibrillators.

Application of X-Ray Pulsar Navigation: A Characterization of the Earth Orbit Trade Space

NASA Technical Reports Server (NTRS)

Yu, Wayne

2016-01-01

The potential for pulsars as a navigation source has been studied since their discovery in 1967. X-ray pulsar navigation (XNAV) is a celestial navigation system that uses the consistent timing nature of x-ray photons from milli-second pulsars (MSP) to perform space navigation. By comparing the detected arrival of x-ray photons to a reference database of expected pulsar lightcurve timing models, one can infer a range and range rate measurement based on light time delay. Much of the challenge of XNAV comes from the faint signal, availability, and distant nature of pulsars. This is a study of potential pulsar XNAV measurements to measure extended Kalman filter (EKF) tracking performance with a wide trade space of bounded Earth orbits, using a simulation of existing x-ray detector space hardware. An example of an x-ray detector for XNAV is the NASA Station Explorer for X-ray Timing and Navigation (SEXTANT) mission, a technology demonstration of XNAV set to perform on the International Space Station (ISS) in late 2016early 2017. XNAV hardware implementation is driven by trajectory and environmental influences which add noise to the x-ray pulse signal. In a closed Earth orbit, the radiation environment can exponentially increase the signal noise from x-ray pulsar sources, decreasing the quality and frequency of measurements. The SEXTANT mission in particular improves on the signal to noise ratio by focusing an array of 56 x-ray silicon drift detectors at one pulsar target at a time. This reduces timing glitches and other timing noise contributions from ambient x-ray sources to within a 100 nanosecond resolution. This study also considers the SEXTANT scheduling challenges inherent in a single target observation. Finally, as the navigation sources are now relatively inertial targets, XNAV measurements are also subject to periods of occultation from various celestial bodies. This study focuses on the characterization of these drivers in closed Earth orbits and is not a tuning analysis of the EKF. The study shows that the closed Earth orbit for XNAV performance is reliant on the orbit semi-major axis and eccentricity as well as orbit inclination. These parameters are the primary drivers of pulsar measurement availability and significantly influence the natural spacecraft orbit dynamics. Sensitivity to initial orbit determination error growth due to the scarcity of XNAV measurements within an orbital period require appropriate timing of initial XNAV measurements. The orbit angles of argument of perigee and right ascension of the ascending node, alongside the other orbit parameters, complete the initial cadence of XNAV measurements. The performance of initial XNAV measurements then propagates throughout the experimental period. The study provides a basis to missions who wish to consider XNAV as a potential navigation source in a closed Earth orbit design. It provides a family of orbit trajectories as well as other modeling considerations needed to effectively evaluate if XNAV is an effective navigation source for a potential mission. As an EKF is sensitive to a linearized estimated state, this study has a direct benefit of providing effective XNAV measurements to maintain spacecraft tracking, independent of other navigation sources. In the particular use case of the SEXTANT mission, it also provides a novel scheduling algorithm which addresses the need to prioritize and manage pulsar observations for effective navigation.

Application of X-Ray Pulsar Navigation: A Characterization of the Earth Orbit Trade Space

NASA Technical Reports Server (NTRS)

Yu, Wayne Hong

2016-01-01

The potential for pulsars as a navigation source has been studied since their discovery in 1967. X-ray pulsar navigation (XNAV) is a celestial navigation system that uses the consistent timing nature of x-ray photons from millisecond pulsars (MSP) to perform space navigation. By comparing the detected arrival of x-ray photons to a reference database of expected pulsar light-curve timing models, one can infer a range and range rate measurement based on light time delay. Much of the challenge of XNAV comes from the faint signal, availability, and distant nature of pulsars. This is a study of potential pulsar XNAV measurements to measure extended Kalman filter (EKF) tracking performance with a wide trade space of bounded Earth orbits, using a simulation of existing x-ray detector space hardware. An example of an x-ray detector for XNAV is the NASA Station Explorer for X-ray Timing and Navigation (SEXTANT) mission, a technology demonstration of XNAV set to perform on the International Space Station (ISS) in late 2016early 2017. XNAV hardware implementation is driven by trajectory and environmental influences which add noise to the x-ray pulse signal. In a closed Earth orbit, the radiation environment can exponentially increase the signal noise from x-ray pulsar sources, decreasing the quality and frequency of measurements. The SEXTANT mission in particular improves on the signal to noise ratio by focusing an array of 56 x-ray silicon drift detectors at one pulsar target at a time. This reduces timing glitches and other timing noise contributions from ambient x-ray sources to within a 100 nanosecond resolution. This study also considers the SEXTANT scheduling challenges inherent in a single target observation. Finally, as the navigation sources are now relatively inertial targets, XNAV measurements are also subject to periods of occultation from various celestial bodies. This study focuses on the characterization of these drivers in closed Earth orbits and is not a tuning analysis of the EKF. The study shows that the closed Earth orbit for XNAV performance is reliant on the orbit semi-major axis and eccentricity as well as orbit inclination. These parameters are the primary drivers of pulsar measurement availability and significantly influence the natural spacecraft orbit dynamics. Sensitivity to initial orbit determination error growth due to the scarcity of XNAV measurements within an orbital period require appropriate timing of initial XNAV measurements. The orbit angles of argument of perigee and right ascension of the ascending node, alongside the other orbit parameters, complete the initial cadence of XNAV measurements. The performance of initial XNAV measurements then propagates throughout the experimental period. The study provides a basis to missions who wish to consider XNAV as a potential navigation source in a closed Earth orbit design. It provides a family of orbit trajectories as well as other modeling considerations needed to effectively evaluate if XNAV is an effective navigation source for a potential mission. As an EKF is sensitive to a linearized estimated state, this study has a direct benefit of providing effective XNAV measurements to maintain spacecraft tracking, independent of other navigation sources. In the particular use case of the SEXTANT mission, it also provides a novel scheduling algorithm which addresses the need to prioritize and manage pulsar observations for effective navigation.

Spacecraft flight simulation: A human factors investigation into the man-machine interface between an astronaut and a spacecraft performing docking maneuvers and other proximity operations

NASA Technical Reports Server (NTRS)

Brody, Adam R.

1988-01-01

The anticipated increase in rendezvous and docking activities in the various space programs in the Space Station era necessitates a renewed interest in manual docking procedures. Ten test subjects participated in computer simulated docking missions in which the influence of initial velocity was examined. All missions started from a resting position of 304.8 meters (1000 feet) along the space station's +V-bar axis. Test subjects controlled their vehicle with a translational hand controller and digital auto pilot which are both virtually identical to their space shuttle counterparts. While the 0.1 percent rule (range rate is equal to 0.1 percent of the range) used by space shuttle pilots is comfortably safe, it is revealed to be extremely inefficient in terms of time and not justifiable in terms of marginal safety. Time is worth money, not only because of training and launch costs, but because the sooner a pilot and spacecraft return from a mission, the sooner they can begin the next one. Inexperienced test subjects reduced the costs of simulated docking by close to a factor of 2 and achieved safe dockings in less than 4 percent of the time the baseline approach would entail. This reduction in time can be used to save lives in the event of an accident on orbit, and can tremendously reduce docking costs if fuel is produced from waste water on orbit.

Analysis of RDSS positioning accuracy based on RNSS wide area differential technique

NASA Astrophysics Data System (ADS)

Xing, Nan; Su, RanRan; Zhou, JianHua; Hu, XiaoGong; Gong, XiuQiang; Liu, Li; He, Feng; Guo, Rui; Ren, Hui; Hu, GuangMing; Zhang, Lei

2013-10-01

The BeiDou Navigation Satellite System (BDS) provides Radio Navigation Service System (RNSS) as well as Radio Determination Service System (RDSS). RDSS users can obtain positioning by responding the Master Control Center (MCC) inquiries to signal transmitted via GEO satellite transponder. The positioning result can be calculated with elevation constraint by MCC. The primary error sources affecting the RDSS positioning accuracy are the RDSS signal transceiver delay, atmospheric trans-mission delay and GEO satellite position error. During GEO orbit maneuver, poor orbit forecast accuracy significantly impacts RDSS services. A real-time 3-D orbital correction method based on wide-area differential technique is raised to correct the orbital error. Results from the observation shows that the method can successfully improve positioning precision during orbital maneuver, independent from the RDSS reference station. This improvement can reach 50% in maximum. Accurate calibration of the RDSS signal transceiver delay precision and digital elevation map may have a critical role in high precise RDSS positioning services.

JEM module

NASA Image and Video Library

2008-06-06

S124-E-006729 (6 June 2008) --- One of a series of digital still images documenting the Japanese Experiment Module, or JEM, also called Kibo, in its new home on the International Space Station, this view depicts Kibo's exterior, backdropped by solar array panels for the orbital outpost.

Empty STS-114 orbiter Discovery Payload bay

NASA Image and Video Library

2005-07-29

ISS011-E-11340 (29 July 2005) --- A "fish-eye" lens on a digital still camera was used to record this image of the Space Shuttle Discovery from the International Space Station, to which it is docked for several days of joint activities.

Close-up view of Sunflower Seeds

NASA Image and Video Library

2013-11-04

ISS037-E-026274 (4 Nov. 2013) --- A two-day old sunflower sprout is being closely monitored in its temporary home inside a plastic bag by the Expedition 37 crew members onboard the Earth-orbiting International Space Station.

Double closed-loop resonant micro optic gyro using hybrid digital phase modulation.

PubMed

Ma, Huilian; Zhang, Jianjie; Wang, Linglan; Jin, Zhonghe

2015-06-15

It is well-known that the closed-loop operation in optical gyros offers wider dynamic range and better linearity. By adding a stair-like digital serrodyne wave to a phase modulator can be used as a frequency shifter. The width of one stair in this stair-like digital serrodyne wave should be set equal to the optical transmission time in the resonator, which is relaxed in the hybrid digital phase modulation (HDPM) scheme. The physical mechanism for this relaxation is firstly indicated in this paper. Detailed theoretical and experimental investigations are presented for the HDPM. Simulation and experimental results show that the width of one stair is not restricted by the optical transmission time, however, it should be optimized according to the rise time of the output of the digital-to-analogue converter. Based on the optimum parameters of the HDPM, a bias stability of 0.05°/s for the integration time of 400 seconds in 1 h has been carried out in an RMOG with a waveguide ring resonator with a length of 7.9 cm and a diameter of 2.5 cm.

High Speed, Low Cost Telemetry Access from Space Development Update on Programmable Ultra Lightweight System Adaptable Radio (PULSAR)

NASA Technical Reports Server (NTRS)

Simms, William Herbert, III; Varnavas, Kosta; Eberly, Eric

2014-01-01

Software Defined Radio (SDR) technology has been proven in the commercial sector since the early 1990's. Today's rapid advancement in mobile telephone reliability and power management capabilities exemplifies the effectiveness of the SDR technology for the modern communications market. In contrast, the foundations of transponder technology presently qualified for satellite applications were developed during the early space program of the 1960's. Conventional transponders are built to a specific platform and must be redesigned for every new bus while the SDR is adaptive in nature and can fit numerous applications with no hardware modifications. A SDR uses a minimum amount of analog / Radio Frequency (RF) components to up/down-convert the RF signal to/from a digital format. Once the signal is digitized, all processing is performed using hardware or software logic. Typical SDR digital processes include; filtering, modulation, up/down converting and demodulation. NASA Marshall Space Flight Center (MSFC) Programmable Ultra Lightweight System Adaptable Radio (PULSAR) leverages existing MSFC SDR designs and commercial sector enhanced capabilities to provide a path to a radiation tolerant SDR transponder. These innovations (1) reduce the cost of NASA Low Earth Orbit (LEO) and Deep Space standard transponders, (2) decrease power requirements, and (3) commensurately reduce volume. A second pay-off is the increased SDR flexibility by allowing the same hardware to implement multiple transponder types simply by altering hardware logic - no change of hardware is required - all of which will ultimately be accomplished in orbit. Development of SDR technology for space applications will provide a highly capable, low cost transponder to programs of all sizes. The MSFC PULSAR Project results in a Technology Readiness Level (TRL) 7 low-cost telemetry system available to Smallsat and CubeSat missions, as well as other platforms. This paper documents the continued development and verification/validation of the MSFC SDR, called PULSAR, which contributes to advancing the state-of-the-art in transponder design - directly applicable to the SmallSat and CubeSat communities. This paper focuses on lessons learned on the first sub-orbital flight (high altitude balloon) and the follow-on steps taken to validate PULSAR. A sounding rocket launch, currently planned for 03/2015, will further expose PULSAR to the high dynamics of sub-orbital flights. Future opportunities for orbiting satellite incorporation reside in the small satellite missions (FASTSat, CubeSat. etc.).

Replantation of digits - series (image)

MedlinePlus

Digital nerves and vessels are repaired with microsurgical instruments. This part of the surgery is most critical to its success. The skin is then closed. A bulky dressing is applied. Young children may have a cast applied to protect the area from injury.

Trajectory Design for the Phobos and Deimos & Mars Environment Spacecraft

NASA Technical Reports Server (NTRS)

Genova, Anthony L.; Korsmeyer, David J.; Loucks, Michel E.; Yang, Fan Yang; Lee, Pascal

2016-01-01

The presented trajectory design and analysis was performed for the Phobos and Deimos & Mars Environment (PADME) mission concept as part of a NASA proposal submission managed by NASA Ames Research Center in the 2014-2015 timeframe. The PADME spacecraft would be a derivative of the successfully flown Lunar Atmosphere & Dust Environment Explorer (LADEE) spacecraft. While LADEE was designed to enter low-lunar orbit, the PADME spacecraft would instead enter an elliptical Mars orbit of 2-week period. This Mars orbit would pass by Phobos near periapsis on successive orbits and then raise periapsis to yield close approaches of Deimos every orbit thereafter.

Orbital evolution of some Centaurs

NASA Astrophysics Data System (ADS)

Kovalenko, Nataliya; Babenko, Yuri; Churyumov, Klim

2002-11-01

In this work we investigated the dynamical evolution of Centaurs objects 2060 (Chiron), 5145 (Pholus), 7066 (Nessus), 8405 (Asbolus), 10199 (Chariklo), 10370 (Hylonome), and Scattered-Disk object 15874. We have carried out orbital integration of test particles with initial orbits similar to those of these objects. Calculations were produced for +/-600kyr-10Myr starting at epoch and using the implicit single sequence Everhart methods. 12 variational orbits for each of selected Centaurs also have been numerically integrated for +/-200 kyr toward the past and the future. The most probable paths were traced up to +/-1 Myr. The character of orbital elements changes and peculiarities of close approaches to giant planets are discussed.

HP-9825A HFRMP trajectory processor (#TRAJ), detailed description. [relative motion of the space shuttle orbiter and a free-flying payload

NASA Technical Reports Server (NTRS)

Kindall, S. M.

1980-01-01

The computer code for the trajectory processor (#TRAJ) of the high fidelity relative motion program is described. The #TRAJ processor is a 12-degrees-of-freedom trajectory integrator (6 degrees of freedom for each of two vehicles) which can be used to generate digital and graphical data describing the relative motion of the Space Shuttle Orbiter and a free-flying cylindrical payload. A listing of the code, coding standards and conventions, detailed flow charts, and discussions of the computational logic are included.

Survey view of damage to the STS-117 OMS Pod taken by an Expedition 15 Crewmember

NASA Image and Video Library

2007-06-13

ISS015E11804 (13 June 2007) --- A digital still camera recorded this image of a gap caused by an uplifted area on the thermal blanket protecting Atlantis' portside orbital maneuvering system (OMS) pod. The STS-117 Mission Management Team (MMT) has decided the best course of action to take in regard to the uplifted thermal blanket on the post side Orbital Maneuvering System Pod was to add the repair task on EVA 3 with astronauts Jim Reilly and John (Danny) Olivas.

STS-48 Pilot Reightler on OV-103's aft flight deck poses for ESC photo

NASA Technical Reports Server (NTRS)

1991-01-01

STS-48 Pilot Kenneth S. Reightler, Jr, positioned under overhead window W8, poses for an electronic still camera (ESC) photo on the aft flight deck of the earth-orbiting Discovery, Orbiter Vehicle (OV) 103. Crewmembers were testing the ESC as part of Development Test Objective (DTO) 648, Electronic Still Photography. The digital image was stored on a removable hard disk or small optical disk, and could be converted to a format suitable for downlink transmission. The ESC is making its initial appearance on this Space Shuttle mission.

IPL Processing of the Viking Orbiter Images of Mars

NASA Technical Reports Server (NTRS)

Ruiz, R. M.; Elliott, D. A.; Yagi, G. M.; Pomphrey, R. B.; Power, M. A.; Farrell, W., Jr.; Lorre, J. J.; Benton, W. D.; Dewar, R. E.; Cullen, L. E.

1977-01-01

The Viking orbiter cameras returned over 9000 images of Mars during the 6-month nominal mission. Digital image processing was required to produce products suitable for quantitative and qualitative scientific interpretation. Processing included the production of surface elevation data using computer stereophotogrammetric techniques, crater classification based on geomorphological characteristics, and the generation of color products using multiple black-and-white images recorded through spectral filters. The Image Processing Laboratory of the Jet Propulsion Laboratory was responsible for the design, development, and application of the software required to produce these 'second-order' products.

Closed circuit TV system automatically guides welding arc

NASA Technical Reports Server (NTRS)

Stephans, D. L.; Wall, W. A., Jr.

1968-01-01

Closed circuit television /CCTV/ system automatically guides a welding torch to position the welding arc accurately along weld seams. Digital counting and logic techniques incorporated in the control circuitry, ensure performance reliability.

Direct Data Distribution From Low-Earth Orbit

NASA Technical Reports Server (NTRS)

Budinger, James M.; Fujikawa, Gene; Kunath, Richard R.; Nguyen, Nam T.; Romanofsky, Robert R.; Spence, Rodney L.

1997-01-01

NASA Lewis Research Center (LeRC) is developing the space and ground segment technologies necessary to demonstrate a direct data distribution (1)3) system for use in space-to-ground communication links from spacecraft in low-Earth orbit (LEO) to strategically located tracking ground terminals. The key space segment technologies include a K-band (19 GHz) MMIC-based transmit phased array antenna, and a multichannel bandwidth- and power-efficient digital encoder/modulate with an aggregate data rate of 622 Mb/s. Along with small (1.8 meter), low-cost tracking terminals on the ground, the D3 system enables affordable distribution of data to the end user or archive facility through interoperability with commercial terrestrial telecommunications networks. The D3 system is applicable to both government and commercial science and communications spacecraft in LEO. The features and benefits of the D3 system concept are described. Starting with typical orbital characteristics, a set of baseline requirements for representative applications is developed, including requirements for onboard storage and tracking terminals, and sample link budgets are presented. Characteristics of the transmit array antenna and digital encoder/modulator are described. The architecture and components of the tracking terminal are described, including technologies for the next generation terminal. Candidate flights of opportunity for risk mitigation and space demonstration of the D3 features are identified.

Spaceflight mechanics 1992; Proceedings of the 2nd AAS/AIAA Meeting, Colorado Springs, CO, Feb. 24-26, 1992. Pts. 1 & 2

NASA Astrophysics Data System (ADS)

Diehl, Roger E.; Schinnerer, Ralph G.; Williamson, Walton E.; Boden, Daryl G.

The present conference discusses topics in orbit determination, tethered satellite systems, celestial mechanics, guidance optimization, flexible body dynamics and control, attitude dynamics and control, Mars mission analyses, earth-orbiting mission analysis/debris, space probe mission analyses, and orbital computation numerical analyses. Attention is given to electrodynamic forces for control of tethered satellite systems, orbiting debris threats to asteroid flyby missions, launch velocity requirements for interceptors of short range ballistic missiles, transfers between libration-point orbits in the elliptic restricted problem, minimum fuel spacecraft reorientation, orbital guidance for hitting a fixed point at maximum speed, efficient computation of satellite visibility periods, orbit decay and reentry prediction for space debris, and the determination of satellite close approaches.

Spaceflight mechanics 1992; Proceedings of the 2nd AAS/AIAA Meeting, Colorado Springs, CO, Feb. 24-26, 1992. Pts. 1 & 2

NASA Technical Reports Server (NTRS)

Diehl, Roger E. (Editor); Schinnerer, Ralph G. (Editor); Williamson, Walton E. (Editor); Boden, Daryl G. (Editor)

1992-01-01

The present conference discusses topics in orbit determination, tethered satellite systems, celestial mechanics, guidance optimization, flexible body dynamics and control, attitude dynamics and control, Mars mission analyses, earth-orbiting mission analysis/debris, space probe mission analyses, and orbital computation numerical analyses. Attention is given to electrodynamic forces for control of tethered satellite systems, orbiting debris threats to asteroid flyby missions, launch velocity requirements for interceptors of short range ballistic missiles, transfers between libration-point orbits in the elliptic restricted problem, minimum fuel spacecraft reorientation, orbital guidance for hitting a fixed point at maximum speed, efficient computation of satellite visibility periods, orbit decay and reentry prediction for space debris, and the determination of satellite close approaches.

Long-term evolution of 1991 DA: A dynamically evolved extinct Halley-type comet

NASA Technical Reports Server (NTRS)

Hahn, Gerhard; Bailey, M. E.

1992-01-01

The long-term dynamical evolution of 21 variational orbits for the intermediate-period asteroid 1991 DA was followed for up to +/-10(exp 5) years from the present. 1991 DA is close to the 2:7 resonance with Jupiter; it has avoided close encounters, within 1 AU, with this planet for at least the past 30,000 years, even at the node crossing. The future evolution typically shows no close encounters with Jupiter within at least 50,000 years. This corresponds to the mean time between node crossings with either Jupiter or Saturn. Close encounters with Saturn and Jupiter lead to a chaotic evolution for the whole ensemble, while secular perturbations cause large-amplitude swings in eccentricity and inclination (the latter covering the range 15 deg approximately less than i approximately less than 85 deg) which correlate with deep excursions of the perihelion distance to values much less than 1 AU. These variations are similar to those found in P/Machholz and a variety of other high-inclination orbits, e.g., P/Hartley-IRAS. We emphasize the connection between the orbital evolution of 1991 DA and that of Halley-type comets. If 1991 DA was once a comet, it is not surprising that it is now extinct.

WD1145+017 (Abstract)

NASA Astrophysics Data System (ADS)

Motta, M.

2017-12-01

(Abstract only) WD1145 is a 17th magnitude white dwarf star 570 light years away in Virgo that was discovered to have a disintegrating planetoid in close orbit by Andrew Vanderburg, a graduate student at Harvard CfA, while data mining the elucidate the nature of its rather bizarre transit light curves. I obtained multiple observations of WD1145 over the course of a year, and found a series of complex transit light curves that could only be interpreted as a ring complex or torus in close orbit around WD1145. Combined with data from other amateur astronomers, professional observations, and satellite data, it became clear that WD1145 has a small planetoid in close orbit at the Roche limit and is breaking apart, forming a ring of debris material that is then raining down on the white dwarf. The surface of the star is "polluted" by heavy metals, determined by spectroscopic data. Given that in the intense gravitational field of a white dwarf any heavy metals could not for long last on the surface, this confirms that we are tracking in real time the destruction of a small planet by its host star.

Initial On-Orbit Radiometric Calibration of the Suomi NPP VIIRS Reflective Solar Bands

NASA Technical Reports Server (NTRS)

Lei, Ning; Wang, Zhipeng; Fulbright, Jon; Lee, Shihyan; McIntire, Jeff; Chiang, Vincent; Xiong, Jack

2012-01-01

The on-orbit radiometric response calibration of the VISible/Near InfraRed (VISNIR) and the Short-Wave InfraRed (SWIR) bands of the Visible/Infrared Imager/Radiometer Suite (VIIRS) aboard the Suomi National Polar-orbiting Partnership (NPP) satellite is carried out through a Solar Diffuser (SD). The transmittance of the SD screen and the SD's Bidirectional Reflectance Distribution Function (BRDF) are measured before launch and tabulated, allowing the VIIRS sensor aperture spectral radiance to be accurately determined. The radiometric response of a detector is described by a quadratic polynomial of the detector?s digital number (dn). The coefficients were determined before launch. Once on orbit, the coefficients are assumed to change by a common factor: the F-factor. The radiance scattered from the SD allows the determination of the F-factor. In this Proceeding, we describe the methodology and the associated algorithms in the determination of the F-factors and discuss the results.

The synchronous orbit magnetic field data set

NASA Technical Reports Server (NTRS)

Mcpherron, R. L.

1979-01-01

The magnetic field at synchronous orbit is the result of superposition of fields from many sources such as the earth, the magnetopause, the geomagnetic tail, the ring current and field-aligned currents. In addition, seasonal changes in the orientation of the earth's dipole axis causes significant changes in each of the external sources. Main reasons for which the synchronous orbit magnetic field data set is a potentially valuable resource are outlined. The primary reason why synchronous magnetic field data have not been used more extensively in magnetic field modeling is the presence of absolute errors in the measured fields. Nevertheless, there exists a reasonably large collection of synchronous orbit magnetic field data. Some of these data can be useful in quantitative modeling of the earth's magnetic field. A brief description is given of the spacecraft, the magnetometers, the standard graphical data displays, and the digital data files.

Autonomous space processor for orbital debris

NASA Technical Reports Server (NTRS)

Ramohalli, Kumar; Campbell, David; Marine, Micky; Saad, Mohamad; Bertles, Daniel; Nichols, Dave

1990-01-01

Advanced designs are being continued to develop the ultimate goal of a GETAWAY special to demonstrate economical removal of orbital debris utilizing local resources in orbit. The fundamental technical feasibility was demonstrated in 1988 through theoretical calculations, quantitative computer animation, a solar focal point cutter, a robotic arm design and a subcase model. Last year improvements were made to the solar cutter and the robotic arm. Also performed last year was a mission analysis which showed the feasibility of retrieve at least four large (greater than 1500 kg) pieces of debris. Advances made during this reporting period are the incorporation of digital control with the existing placement arm, the development of a new robotic manipulator arm, and the study of debris spin attenuation. These advances are discussed.

KSC-04PD-1812

NASA Technical Reports Server (NTRS)

2004-01-01

KENNEDY SPACE CENTER, FLA. In the Orbiter Processing Facility, United Space Alliance worker Craig Meyer fits an External Tank (ET) digital still camera in the right-hand liquid oxygen umbilical well on Space Shuttle Atlantis. NASA is pursuing use of the camera, beginning with the Shuttles Return To Flight, to obtain and downlink high-resolution images of the ET following separation of the ET from the orbiter after launch. The Kodak camera will record 24 images, at one frame per 1.5 seconds, on a flash memory card. After orbital insertion, the crew will transfer the images from the memory card to a laptop computer. The files will then be downloaded through the Ku-band system to the Mission Control Center in Houston for analysis.

KSC-04PD-1813

NASA Technical Reports Server (NTRS)

2004-01-01

KENNEDY SPACE CENTER, FLA. In the Orbiter Processing Facility, an External Tank (ET) digital still camera is positioned into the right-hand liquid oxygen umbilical well on Space Shuttle Atlantis to determine if it fits properly. NASA is pursuing use of the camera, beginning with the Shuttles Return To Flight, to obtain and downlink high-resolution images of the ET following separation of the ET from the orbiter after launch. The Kodak camera will record 24 images, at one frame per 1.5 seconds, on a flash memory card. After orbital insertion, the crew will transfer the images from the memory card to a laptop computer. The files will then be downloaded through the Ku-band system to the Mission Control Center in Houston for analysis.

KSC-04pd1813

NASA Image and Video Library

2004-09-17

KENNEDY SPACE CENTER, FLA. - In the Orbiter Processing Facility, an External Tank (ET) digital still camera is positioned into the right-hand liquid oxygen umbilical well on Space Shuttle Atlantis to determine if it fits properly. NASA is pursuing use of the camera, beginning with the Shuttle’s Return To Flight, to obtain and downlink high-resolution images of the ET following separation of the ET from the orbiter after launch. The Kodak camera will record 24 images, at one frame per 1.5 seconds, on a flash memory card. After orbital insertion, the crew will transfer the images from the memory card to a laptop computer. The files will then be downloaded through the Ku-band system to the Mission Control Center in Houston for analysis.

KSC-04pd1812

NASA Image and Video Library

2004-09-17

KENNEDY SPACE CENTER, FLA. - In the Orbiter Processing Facility, United Space Alliance worker Craig Meyer fits an External Tank (ET) digital still camera in the right-hand liquid oxygen umbilical well on Space Shuttle Atlantis. NASA is pursuing use of the camera, beginning with the Shuttle’s Return To Flight, to obtain and downlink high-resolution images of the ET following separation of the ET from the orbiter after launch. The Kodak camera will record 24 images, at one frame per 1.5 seconds, on a flash memory card. After orbital insertion, the crew will transfer the images from the memory card to a laptop computer. The files will then be downloaded through the Ku-band system to the Mission Control Center in Houston for analysis.

Analysis of space shuttle orbiter entry dynamics from Mach 10 to Mach 2.5 with the November 1976 flight control system

NASA Technical Reports Server (NTRS)

Powell, R. W.; Stone, H. W.

1980-01-01

A six-degree-of-freedom simulation analysis was performed for the space shuttle orbiter entry from Mach 10 to Mach 2.5 with realistic off-nominal conditions using the flight control system referred to as the November 1976 Integrated Digital Autopilot. The off-nominal conditions included: (1) aerodynamic uncertainties in extrapolating from wind tunnel of flight characteristics, (2) error in deriving angle of attack from onboard instrumentation, (3) failure of two of the four reaction control-system thrusters on each side (design specification), and (4) lateral center-of-gravity offset. Many combinations of these off-nominal conditions resulted in a loss of the orbiter. Control-system modifications were identified to prevent this possibility.

An Orbital Angular Momentum (OAM) Mode Reconfigurable Antenna for Channel Capacity Improvement and Digital Data Encoding.

PubMed

Liu, Baiyang; Lin, Guoying; Cui, Yuehui; Li, RongLin

2017-08-29

For purpose of utilizing orbital angular momentum (OAM) mode diversity, multiple OAM beams should be generated preferably by a single antenna. In this paper, an OAM mode reconfigurable antenna is proposed. Different from the existed OAM antennas with multiple ports for multiple OAM modes transmitting, the proposed antenna with only a single port, but it can be used to transmit mode 1 or mode -1 OAM beams arbitrary by controlling the PIN diodes on the feeding network through a programmable microcontroller which control by a remote controller. Simulation and measurement results such as return loss, near-field and far-field radiation patterns of two operating states for mode 1 and mode -1, and OAM mode orthogonality are given. The proposed antenna can serve as a candidate for utilizing OAM diversity, namely phase diversity to increase channel capacity at 2.4 GHz. Moreover, an OAM-mode based encoding method is experimentally carried out by the proposed OAM mode reconfigurable antenna, the digital data are encoded and decoded by different OAM modes. At the transmitter, the proposed OAM mode reconfigurable antenna is used to encode the digital data, data symbol 0 and 1 are mapped to OAM mode 1 and mode -1, respectively. At the receiver, the data symbols are decoded by phase gradient method.

How to Take 30 Years Off the Life of an Earth-Orbiter Network

NASA Technical Reports Server (NTRS)

Berner, C. D.; Perkins, R. C.; Baker, N.

1995-01-01

In the mid 1960's the NASA/JPL Deep Space Network installed a global 26-meter antenna network to support a large group of Low Earth Orbiters and Highly Elliptical Orbiters. Although this network was equipped with then state-of-the-art equipment, operations were labor- intensive. A study is discussed which takes a close look at re- engineering the 26-meter antenna network from all aspects.

Closeup view of the payload bay side of the aft ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Close-up view of the payload bay side of the aft crew compartment bulkhead of the Orbiter Discovery. Showing the airlock, the beam-truss attach structure supporting it and its attach points to the payload bay sill longerons. This photograph was taken in the Orbiter Processing Facility at Kennedy Space Center. - Space Transportation System, Orbiter Discovery (OV-103), Lyndon B. Johnson Space Center, 2101 NASA Parkway, Houston, Harris County, TX

General view looking aft from the starboard side of the ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

General view looking aft from the starboard side of the mid fuselage of the Orbiter Discovery. This view has a close-up view of the remote sensor boom and its retention mechanisms at its attach points to the starboard longeron. This photograph was taken in the Orbiter Processing Facility at the Kennedy Space Center. - Space Transportation System, Orbiter Discovery (OV-103), Lyndon B. Johnson Space Center, 2101 NASA Parkway, Houston, Harris County, TX

Closeup view of a Space Shuttle Main Engine (SSME) installed ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Close-up view of a Space Shuttle Main Engine (SSME) installed in position number one on the Orbiter Discovery. A ground-support mobile platform is in place below the engine to assist in technicians with the installation of the engine. This Photograph was taken in the Orbiter Processing Facility at the Kennedy Space Center. - Space Transportation System, Orbiter Discovery (OV-103), Lyndon B. Johnson Space Center, 2101 NASA Parkway, Houston, Harris County, TX

Use of a caudal auricular axial pattern flap in three cats and one dog following orbital exenteration.

PubMed

Stiles, Jean; Townsend, Wendy; Willis, Michelle; Moore, Phillip A; Smith, Eric

2003-06-01

Orbital exenteration accompanied by wide eyelid excision in the cat and dog may leave a defect that cannot be closed in a primary fashion. This report describes the use of a caudal auricular axial pattern flap to effect closure following orbital exenteration in three cats and one dog. The most common complication was distal flap necrosis, which necessitated a second surgery in two patients.

Digital Radiography Qualification of Tube Welding

NASA Technical Reports Server (NTRS)

Carl, Chad

2012-01-01

The Orion Project will be directing Lockheed Martin to perform orbital arc welding on commodities metallic tubing as part of the Multi Purpose Crew Vehicle assembly and integration process in the Operations and Checkout High bay at Kennedy Space Center. The current method of nondestructive evaluation is utilizing traditional film based x-rays. Due to the high number of welds that are necessary to join the commodities tubing (approx 470), a more efficient and expeditious method of nondestructive evaluation is desired. Digital radiography will be qualified as part of a broader NNWG project scope.

Mars Digital Image Mosaic Globe

NASA Technical Reports Server (NTRS)

2000-01-01

The photomosaic that forms the base for this globe was created by merging two global digital image models (DIM's) of Mars-a medium-resolution monochrome mosaic processed to emphasize topographic features and a lower resolution color mosaic emphasizing color and albedo variations.

The medium-resolution (1/256 or roughly 231 m/pixel) monochromatic image model was constructed from about 6,000 images having resolutions of 150-350 m/pixel and oblique illumination (Sun 20 o -45 o above the horizon). Radiometric processing was intended to suppress or remove the effects of albedo variations through the use of a high-pass divide filter, followed by photometric normalization so that the contrast of a given topographic slope would be approximately the same in all images.

The global color mosaic was assembled at 1/64 or roughly 864 m/pixel from about 1,000 red- and green-filter images having 500-1,000 m/pixel resolution. These images were first mosaiced in groups, each taken on a single orbit of the Viking spacecraft. The orbit mosaics were then processed to remove spatially and temporally varying atmospheric haze in the overlap regions. After haze removal, the per-orbit mosaics were photometrically normalized to equalize the contrast of albedo features and mosaiced together with cosmetic seam removal. The medium-resolution DIM was used for geometric control of this color mosaic. A green-filter image was synthesized by weighted averaging of the red- and violet-filter mosaics. Finally, the product seen here was obtained by multiplying each color image by the medium-resolution monochrome image. The color balance selected for images in this map series was designed to be close to natural color for brighter, redder regions, such as Arabia Terra and the Tharsis region, but the data have been stretched so that the relatively dark regions appear darker and less red than they actually are.

The images are presented in a projection that portrays the entire surface of Mars in a manner suitable for the production of a globe; the number, size, and placement of text annotations were chosen for a 12-inch globe. Prominent features are labeled with names approved by the International Astronomical Union. A specialized program was used to create the 'flower petal' appearance of the images; the area of each petal from 0 to 75 degrees latitude is in the Transverse Mercator projection, and the area from 75 to 90 degrees latitude is in the Lambert Azimuthal Equal-Area projection. The northern hemisphere of Mars is shown on the left, and the southern hemisphere on the right.

Evaluation of the effects of the seasonal variation of solar elevation angle and azimuth on the processes of digital filtering and thematic classification of relief units

NASA Technical Reports Server (NTRS)

Parada, N. D. J. (Principal Investigator); Novo, E. M. L. M.

1983-01-01

The effects of the seasonal variation of illumination over digital processing of LANDSAT images are evaluated. Two sets of LANDSAT data referring to the orbit 150 and row 28 were selected with illumination parameters varying from 43 deg to 64 deg for azimuth and from 30 deg to 36 deg for solar elevation respectively. IMAGE-100 system permitted the digital processing of LANDSAT data. Original images were transformed by means of digital filtering so as to enhance their spatial features. The resulting images were used to obtain an unsupervised classification of relief units. Topographic variables (declivity, altitude, relief range and slope length) were used to identify the true relief units existing on the ground. The LANDSAT over pass data show that digital processing is highly affected by illumination geometry, and there is no correspondence between relief units as defined by spectral features and those resulting from topographic features.

Tri-state delta modulation system for Space Shuttle digital TV downlink

NASA Technical Reports Server (NTRS)

Udalov, S.; Huth, G. K.; Roberts, D.; Batson, B. H.

1981-01-01

Future requirements for Shuttle Orbiter downlink communication may include transmission of digital video which, in addition to black and white, may also be either field-sequential or NTSC color format. The use of digitized video could provide for picture privacy at the expense of additional onboard hardware, together with an increased bandwidth due to the digitization process. A general objective for the Space Shuttle application is to develop a digitization technique that is compatible with data rates in the 20-30 Mbps range but still provides good quality pictures. This paper describes a tri-state delta modulation/demodulation (TSDM) technique which is a good compromise between implementation complexity and performance. The unique feature of TSDM is that it provides for efficient run-length encoding of constant-intensity segments of a TV picture. Axiomatix has developed a hardware implementation of a high-speed TSDM transmitter and receiver for black-and-white TV and field-sequential color. The hardware complexity of this TSDM implementation is summarized in the paper.

Valley Network Morphology and Topographic Gradients on Mars

NASA Technical Reports Server (NTRS)

Aharonson, Oded; Zuber, Maria T.; Rothman, Daniel H.; Schorghofer, Norbert; Phillips, Roger J.; Williams, Rebecca M. E.

2001-01-01

Data returned from the Mars Orbiter Laser Altimeter allows construction of a high precision digital elevation model. Quantitative investigations into the geomorphic properties of drainage features, similar to ones carried out on Earth, are now possible Additional information is contained in the original extended abstract.

Global Geometric Properties of Martian Impact Craters: An Assessment from Mars Orbiter Laser Altimeter (MOLA) Digital Elevation Models

NASA Technical Reports Server (NTRS)

Garvin, J. B.; Frawley, J. J.; Sakimoto, S. E. H.; Schnetzler, C.

2000-01-01

Global geometric characteristics of topographically fresh impact craters have been assessed, for the first time, from gridded MOLA topography. Global trends of properties such as depth/diameter differ from previous estimates. Regional differences are observed.

A digital beamforming processor for the joint DoD/NASA space based radar mission

NASA Technical Reports Server (NTRS)

Fischman, Mark A.; Le, Charles; Rosen, Paul A.

2004-01-01

The Space Based Radar (SBR) program includes a joint technology demonstration between NASA and the Air Force to design a low-earth orbiting, 2x50 m L-band radar system for both Earth science and intelligence related observations.

A Free-Return Earth-Moon Cycler Orbit for an Interplanetary Cruise Ship

NASA Technical Reports Server (NTRS)

Genova, Anthony L.; Aldrin, Buzz

2015-01-01

A periodic circumlunar orbit is presented that can be used by an interplanetary cruise ship for regular travel between Earth and the Moon. This Earth-Moon cycler orbit was revealed by introducing solar gravity and modest phasing maneuvers (average of 39 m/s per month) which yields close-Earth encounters every 7 or 10 days. Lunar encounters occur every 26 days and offer the chance for a smaller craft to depart the cycler and enter lunar orbit, or head for a Lagrange point (e.g., EM-L2 halo orbit), distant retrograde orbit (DRO), or interplanetary destination such as a near-Earth object (NEO) or Mars. Additionally, return-to-Earth abort options are available from many points along the cycling trajectory.

A simplified close range photogrammetry method for soil erosion assessment

USDA-ARS?s Scientific Manuscript database

With the increased affordability of consumer grade cameras and the development of powerful image processing software, digital photogrammetry offers a competitive advantage as a tool for soil erosion estimation compared to other technologies. One bottleneck of digital photogrammetry is its dependency...

STS-48 ESC image of the MODE-01 Fluid Test Article (FTA) on OV-103's middeck

NASA Technical Reports Server (NTRS)

1991-01-01

An electronic still camera (ESC) closeup shows the STS-48 Middeck Zero ('0') Gravity Dynamics Experiment 01 (MODE-01) Fluid Test Article (FTA) attached to an experimental support module (ESM) located in a forward middeck locker onboard the earth-orbiting Discovery, Orbiter Vehicle (OV) 103. The FTA is a 3.1-cm diameter cylindrical sealed Lexan tank. The FTA electromagnetic actuator has excited the test article sinusoidally, which causes the fluid inside the tank to slosh. These slosh forces, along with other data such as acceleration levels of the entire assembly, are measured by the force balance and recorded in digital form on an optical disk for later ground analysis. Crewmembers were testing the ESC as part of Development Test Objective (DTO) 648, Electronic Still Photography. The digital image was stored on a removable hard disk or small optical disk, and could be converted to a format suitable for downlink transmission. The ESC is making its initial appearance on this Space Shutt

Mars Digital Image Model 2.1 Control Network

NASA Technical Reports Server (NTRS)

Archinal, B. A.; Kirk, R. L.; Duxbury, T. C.; Lee, E. M.; Sucharski, R.; Cook, D.

2003-01-01

USGS is currently preparing a new version of its global Mars digital image mosaic, which will be known as MDIM 2.1. As part of this process we are completing a new photogrammetric solution of the global Mars control network. This is an improved version of the network established earlier by RAND and USGS personnel, as partially described previously. MDIM 2.1 will have many improvements over earlier Viking Orbiter (VO) global mosaics. Geometrically, it will be an orthoimage product, draped on Mars Orbiter Laser Altimeter (MOLA) derived topography, thus accounting properly for the commonly oblique VO imagery. Through the network being described here it will be tied to the newly defined IAU/IAG 2000 Mars coordinate system via ties to MOLA data. Thus, MDIM 2.1 will provide complete global orthorectified imagery coverage of Mars at the resolution of 1/256 deg of MDIM 2.0, and be compatible with MOLA and other products produced in the current coordinate system.

Closeup view of the reinforced carboncarbon nose on the forward ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Close-up view of the reinforced carbon-carbon nose on the forward section of the Orbiter Discovery's in the Vehicle Assembly Building at NASA's Kennedy Space Center. - Space Transportation System, Orbiter Discovery (OV-103), Lyndon B. Johnson Space Center, 2101 NASA Parkway, Houston, Harris County, TX

Mars Orbiters Duck and Cover for Comet Siding Spring Flyby Artist Concept

NASA Image and Video Library

2014-10-09

This artist concept shows NASA Mars orbiters lining up behind the Red Planet for their duck and cover maneuver to shield them from comet dust that may result from the close flyby of comet Siding Spring C/2013 A1 on Oct. 19, 2014.

GN/C translation and rotation control parameters for AR/C (category 2)

NASA Technical Reports Server (NTRS)

Henderson, David M.

1991-01-01

Detailed analysis of the Automatic Rendezvous and Capture problem indicate a need for three different regions of mathematical description for the GN&C algorithms: (1) multi-vehicle orbital mechanics to the rendezvous interface point, i.e., within 100 n.; (2) relative motion solutions (such as Clohessy-Wiltshire type) from the far-field to the near-field interface, i.e., within 1 nm; and (3) close proximity motion, the nearfield motion where the relative differences in the gravitational and orbit inertial accelerations can be neglected from the equations of motion. This paper defines the reference coordinate frames and control parameters necessary to model the relative motion and attitude of spacecraft in the close proximity of another space system (Region 2 and 3) during the Automatic Rendezvous and Capture phase of an orbit operation.

A simultaneous estimation of the mass of Mars and its natural satellites, Phobos and Deimos, from the orbital perturbations on the Mariner 9, Viking 1, and Viking 2 orbiters

NASA Technical Reports Server (NTRS)

Lemoine, F. G.; Smith, D. E.; Fricke, S. K.; Mccarthy, J. J.

1993-01-01

The natural satellites of Mars, Phobos and Deimos, caused perturbations on the orbits of the Mariner 9, and the Viking spacecraft that were used to estimate the satellite masses. The Viking spacecraft were specifically targeted to make close flybys (within a few hundred kilometers) of Phobos in February 1977 and of Deimos in October 1977. These close encounters were used to estimate the moon's gravitational constant, GM (the universal constant of gravitation multiplied by the satellite mass). However, the Viking and Mariner 9 spacecraft made numerous flybys of Phobos and Deimos at distances of a few thousand kilometers. The tracking data from these more 'distant' encounters were processed to estimate the masses of Mars, Phobos, and Deimos.

Dynamical effects of stellar companions

NASA Astrophysics Data System (ADS)

Naoz, Smadar

2015-08-01

The fraction of stellar binaries in the field is extremely high (about 40% - 70% for > 1 Msun stars), and thus, given this frequency, a large fraction of all exoplanetary systems may reside in binaries. While close-in giant planets tend to be found preferentially in binary stellar systems it seems that the frequency of giant planets in close binaries (<100 AU) is significantly lower than in the overall population. Stellar companions’ gravitational perturbations may significantly alter the planetary orbits around their partner on secular timescales. They can drive planets to large eccentric orbits which can either result in plunging these planets into the star or shrinking their orbits and forming short period planets. I will review the dynamical effects stellar binaries have on a planetary systems. I will also present new results on the influence that stellar evolution has on the dynamical processes in these systems.

NASA Tech Briefs, April 2011

NASA Technical Reports Server (NTRS)

2011-01-01

Topics covered include: Amperometric Solid Electrolyte Oxygen Microsensors with Easy Batch Fabrication; Two-Axis Direct Fluid Shear Stress Sensor for Aerodynamic Applications; Target Assembly to Check Boresight Alignment of Active Sensors; Virtual Sensor Test Instrumentation; Evaluation of the Reflection Coefficient of Microstrip Elements for Reflectarray Antennas; Miniaturized Ka-Band Dual-Channel Radar; Continuous-Integration Laser Energy Lidar Monitor; Miniaturized Airborne Imaging Central Server System; Radiation-Tolerant, SpaceWire-Compatible Switching Fabric; Small Microprocessor for ASIC or FPGA Implementation; Source-Coupled, N-Channel, JFET-Based Digital Logic Gate Structure Using Resistive Level Shifters; High-Voltage-Input Level Translator Using Standard CMOS; Monitoring Digital Closed-Loop Feedback Systems; MASCOT - MATLAB Stability and Control Toolbox; MIRO Continuum Calibration for Asteroid Mode; GOATS Image Projection Component; Coded Modulation in C and MATLAB; Low-Dead-Volume Inlet for Vacuum Chamber; Thermal Control Method for High-Current Wire Bundles by Injecting a Thermally Conductive Filler; Method for Selective Cleaning of Mold Release from Composite Honeycomb Surfaces; Infrared-Bolometer Arrays with Reflective Backshorts; Commercialization of LARC (trade mark) -SI Polyimide Technology; Novel Low-Density Ablators Containing Hyperbranched Poly(azomethine)s; Carbon Nanotubes on Titanium Substrates for Stray Light Suppression; Monolithic, High-Speed Fiber-Optic Switching Array for Lidar; Grid-Tied Photovoltaic Power System; Spectroelectrochemical Instrument Measures TOC; A Miniaturized Video System for Monitoring Drosophila Behavior; Hydrofocusing Bioreactor Produces Anti-Cancer Alkaloids; Creep Measurement Video Extensometer; Radius of Curvature Measurement of Large Optics Using Interferometry and Laser Tracker n-B-pi-p Superlattice Infrared Detector; Safe Onboard Guidance and Control Under Probabilistic Uncertainty; General Tool for Evaluating High-Contrast Coronagraphic Telescope Performance Error Budgets; Hidden Statistics of Schroedinger Equation; Optimal Padding for the Two-Dimensional Fast Fourier Transform; Spatial Query for Planetary Data; Higher Order Mode Coupling in Feed Waveguide of a Planar Slot Array Antenna; Evolutionary Computational Methods for Identifying Emergent Behavior in Autonomous Systems; Sampling Theorem in Terms of the Bandwidth and Sampling Interval; Meteoroid/Orbital Debris Shield Engineering Development Practice and Procedure; Self-Balancing, Optical-Center-Pivot, Fast-Steering Mirror; Wireless Orbiter Hang-Angle Inclinometer System; and Internal Electrostatic Discharge Monitor - IESDM.

Architectures of planetary systems and implications for their formation.

PubMed

Ford, Eric B

2014-09-02

Doppler planet searches revealed that many giant planets orbit close to their host star or in highly eccentric orbits. These and subsequent observations inspired new theories of planet formation that invoke gravitation interactions in multiple planet systems to explain the excitation of orbital eccentricities and even short-period giant planets. Recently, NASA's Kepler mission has identified over 300 systems with multiple transiting planet candidates, including many potentially rocky planets. Most of these systems include multiple planets with closely spaced orbits and sizes between that of Earth and Neptune. These systems represent yet another new and unexpected class of planetary systems and provide an opportunity to test the theories developed to explain the properties of giant exoplanets. Presently, we have limited knowledge about such planetary systems, mostly about their sizes and orbital periods. With the advent of long-term, nearly continuous monitoring by Kepler, the method of transit timing variations (TTVs) has blossomed as a new technique for characterizing the gravitational effects of mutual planetary perturbations for hundreds of planets. TTVs can provide precise, but complex, constraints on planetary masses, densities, and orbits, even for planetary systems with faint host stars. In the coming years, astronomers will translate TTV observations into increasingly powerful constraints on the formation and orbital evolution of planetary systems with low-mass planets. Between TTVs, improved Doppler surveys, high-contrast imaging campaigns, and microlensing surveys, astronomers can look forward to a much better understanding of planet formation in the coming decade.

Architectures of planetary systems and implications for their formation

PubMed Central

Ford, Eric B.

2014-01-01

Doppler planet searches revealed that many giant planets orbit close to their host star or in highly eccentric orbits. These and subsequent observations inspired new theories of planet formation that invoke gravitation interactions in multiple planet systems to explain the excitation of orbital eccentricities and even short-period giant planets. Recently, NASA’s Kepler mission has identified over 300 systems with multiple transiting planet candidates, including many potentially rocky planets. Most of these systems include multiple planets with closely spaced orbits and sizes between that of Earth and Neptune. These systems represent yet another new and unexpected class of planetary systems and provide an opportunity to test the theories developed to explain the properties of giant exoplanets. Presently, we have limited knowledge about such planetary systems, mostly about their sizes and orbital periods. With the advent of long-term, nearly continuous monitoring by Kepler, the method of transit timing variations (TTVs) has blossomed as a new technique for characterizing the gravitational effects of mutual planetary perturbations for hundreds of planets. TTVs can provide precise, but complex, constraints on planetary masses, densities, and orbits, even for planetary systems with faint host stars. In the coming years, astronomers will translate TTV observations into increasingly powerful constraints on the formation and orbital evolution of planetary systems with low-mass planets. Between TTVs, improved Doppler surveys, high-contrast imaging campaigns, and microlensing surveys, astronomers can look forward to a much better understanding of planet formation in the coming decade. PMID:24778212

ESA personal communications and digital audio broadcasting systems based on non-geostationary satellites

NASA Technical Reports Server (NTRS)

Logalbo, P.; Benedicto, J.; Viola, R.

1993-01-01

Personal Communications and Digital Audio Broadcasting are two new services that the European Space Agency (ESA) is investigating for future European and Global Mobile Satellite systems. ESA is active in promoting these services in their various mission options including non-geostationary and geostationary satellite systems. A Medium Altitude Global Satellite System (MAGSS) for global personal communications at L and S-band, and a Multiregional Highly inclined Elliptical Orbit (M-HEO) system for multiregional digital audio broadcasting at L-band are described. Both systems are being investigated by ESA in the context of future programs, such as Archimedes, which are intended to demonstrate the new services and to develop the technology for future non-geostationary mobile communication and broadcasting satellites.

A wideband-PCM recorder for the Space Shuttle orbiter

NASA Technical Reports Server (NTRS)

Petit, R. D.

1976-01-01

The Shuttle wideband-PCM recorder accomplishes recording on up to 14 data tracks with analog or digital data inputs. FM multiplexed analog frequencies of up to 2 MHz and digital rates of 1 Mb/s are accommodated at a tape speed of 120 in/s. Recording time in analog mode varies between 4 min for 2 MHz data to 80 min for 100 kHz data. The total digital data storage is 3.44 x 10 to the 9th bits with recording times from 1 hour for 1 Mb/s to 19 hours for 50 Kb/s data in the serial track switching mode. A versatile command decoder and control interface are used for eight primary modes of operation.

Teetering Stars: Resonant Excitation of Stellar Obliquities by Hot and Warm Jupiters with External Companions

NASA Astrophysics Data System (ADS)

Anderson, Kassandra; Lai, Dong

2018-04-01

Stellar spin-orbit misalignments (obliquities) in hot Jupiter systems have been extensively probed in recent years thanks to Rossiter-McLaughlin observations. Such obliquities may reveal clues about hot Jupiter dynamical and migration histories. Common explanations for generating stellar obliquities include high-eccentricity migration, or primordial disk misalignment. This talk investigates another mechanism for producing stellar spin-orbit misalignments in systems hosting a close-in giant planet with an external, inclined planetary companion. Spin-orbit misalignment may be excited due to a secular resonance, occurring when the precession rate of the stellar spin axis (due to the inner orbit) becomes comparable to the precession rate of the inner orbital axis (due to the outer companion). Due to the spin-down of the host star via magnetic braking, this resonance may be achieved at some point during the star's main sequence lifetime for a wide range of giant planet masses and orbital architectures. We focus on both hot Jupiters (with orbital periods less than ten days) and warm Jupiters (with orbital periods around tens of days), and identify the outer perburber properties needed to generate substantial obliquities via resonant excitation, in terms of mass, separation, and inclination. For hot Jupiters, the stellar spin axis is strongly coupled to the orbital axis, and resonant excitation of obliquity requires a close perturber, located within 1-2 AU. For warm Jupiters, the spin and orbital axes are more weakly coupled, and the resonance may be achieved for more distant perturbers (at several to tens of AU). Resonant excitation of the stellar obliquity is accompanied by a decrease in the planets' mutual orbital inclination, and can thus erase high mutual inclinations in two-planet systems. Since many warm Jupiters are known to have outer planetary companions at several AU or beyond, stellar obliquities in warm Jupiter systems may be common, regardless of the formation/migration mechanism. Future observations probing warm Jupiter obliquities may indicate the presence of a hitherto undetected outer companion.

Jupiter Analogs Orbit Stars with an Average Metallicity Close to That of the Sun

NASA Astrophysics Data System (ADS)

Buchhave, Lars A.; Bitsch, Bertram; Johansen, Anders; Latham, David W.; Bizzarro, Martin; Bieryla, Allyson; Kipping, David M.

2018-03-01

Jupiter played an important role in determining the structure and configuration of the Solar System. Whereas hot-Jupiter type exoplanets preferentially form around metal-rich stars, the conditions required for the formation of planets with masses, orbits, and eccentricities comparable to Jupiter (Jupiter analogs) are unknown. Using spectroscopic metallicities, we show that stars hosting Jupiter analogs have an average metallicity close to solar, in contrast to their hot-Jupiter and eccentric cool-Jupiter counterparts, which orbit stars with super-solar metallicities. Furthermore, the eccentricities of Jupiter analogs increase with host-star metallicity, suggesting that planet–planet scatterings producing highly eccentric cool Jupiters could be more common in metal-rich environments. To investigate a possible explanation for these metallicity trends, we compare the observations to numerical simulations, which indicate that metal-rich stars typically form multiple Jupiters, leading to planet–planet interactions and, hence, a prevalence of either eccentric cool Jupiters or hot Jupiters with circularized orbits. Although the samples are small and exhibit variations in their metallicities, suggesting that numerous processes other than metallicity affect the formation of planetary systems, the data in hand suggests that Jupiter analogs and terrestrial-sized planets form around stars with average metallicities close to solar, whereas high-metallicity systems preferentially host eccentric cool Jupiter or hot Jupiters, indicating that higher metallicity systems may not be favorable for the formation of planetary systems akin to the Solar System.

Close encounters with PHOBOS

NASA Astrophysics Data System (ADS)

Zakharov, A. V.

1988-07-01

Aspects of the Soviet mission to Phobos are examined, including the objectives of the mission, the spapcecraft, experiments, and landers. Past Mars research and unanswered questions concerning Mars and its satellites are discussed. The spacecraft is expected to reach Mars in early 1989 and to observe the planet from two orbits, coming as close as 500 km from the surface, before moving into a third path close to Phobos. After studying the Phobos terrain from above, the craft will jettison one or two small long-duration automated landers, which will perform surface experiments, including work on celestial mechanics, the history of the Phobos orbit, surface composition, and mechanical properties. In addition to studying Phobos and Mars, the craft will examine the interplanetary medium, make observations of the Sun, and possibly study Deimos.

Integrated dynamic analysis simulation of space stations with controllable solar array

NASA Technical Reports Server (NTRS)

Heinrichs, J. A.; Fee, J. J.

1972-01-01

A methodology is formulated and presented for the integrated structural dynamic analysis of space stations with controllable solar arrays and non-controllable appendages. The structural system flexibility characteristics are considered in the dynamic analysis by a synthesis technique whereby free-free space station modal coordinates and cantilever appendage coordinates are inertially coupled. A digital simulation of this analysis method is described and verified by comparison of interaction load solutions with other methods of solution. Motion equations are simulated for both the zero gravity and artificial gravity (spinning) orbital conditions. Closed loop controlling dynamics for both orientation control of the arrays and attitude control of the space station are provided in the simulation by various generic types of controlling systems. The capability of the simulation as a design tool is demonstrated by utilizing typical space station and solar array structural representations and a specific structural perturbing force. Response and interaction load solutions are presented for this structural configuration and indicate the importance of using an integrated type analysis for the predictions of structural interactions.

Photocopy of photograph (digital image located in LBNL Photo Lab ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Photocopy of photograph (digital image located in LBNL Photo Lab Collection, XBD200503-00117-034). March 2005. MOUSE AT EAST TANGENT WITH COVER CLOSED, LOOKING TOWARD CENTER IGLOO, BEVATRON - University of California Radiation Laboratory, Bevatron, 1 Cyclotron Road, Berkeley, Alameda County, CA

A simplified close range photogrammetric technique for soil erosion assessment

USDA-ARS?s Scientific Manuscript database

Surface reconstruction using digital photogrammetry offers a great advantage for soil erosion research. The technology can be cumbersome for field application as it relies on the accurate measurement of control points often using a survey grade instruments. Also, even though digital photogrammetry h...

Computer processing of Mars Odyssey THEMIS IR imaging, MGS MOLA altimetry and Mars Express stereo imaging to locate Airy-0, the Mars prime meridian reference

NASA Astrophysics Data System (ADS)

Duxbury, Thomas; Neukum, Gerhard; Smith, David E.; Christensen, Philip; Neumann, Gregory; Albee, Arden; Caplinger, Michael; Seregina, N. V.; Kirk, Randolph L.

The small crater Airy-0 was selected from Mariner 9 images to be the reference for the Mars prime meridian. Initial analyses were made in year 2000 to tie Viking Orbiter and Mars Orbiter Camera images of Airy-0 to the evolving Mars Orbiter Laser Altimeter global digital terrain model to improve the location accuracy of Airy-0. Based upon this tie and radiometric tracking of landers / rovers from earth, new expressions for the Mars spin axis direction, spin rate and prime meridian epoch value were produced to define the orientation of the Martian surface in inertial space over time. Now that the Mars Global Surveyor mission and the Mars Orbiter Laser Altimeter global digital terrain model are complete, a more exhaustive study has been performed to determine the location of Airy-0 relative to the global terrain grid. THEMIS IR image cubes of the Airy and Gale crater regions were tied to the global terrain grid using precision stereo photogrammetric image processing techniques. The Airy-0 location was determined to be within 50 meters of the currently defined IAU prime meridian, with this offset at the limiting absolute accuracy of the global terrain grid. Additional outputs of this study were a controlled multi-band photomosaic of Airy, precision alignment and geometric models of the ten THEMIS IR bands and a controlled multi-band photomosaic of Gale crater used to validate the Mars Surface Laboratory operational map products supporting their successful landing on Mars.

Floating-point system quantization errors in digital control systems

NASA Technical Reports Server (NTRS)

Phillips, C. L.

1973-01-01

The results are reported of research into the effects on system operation of signal quantization in a digital control system. The investigation considered digital controllers (filters) operating in floating-point arithmetic in either open-loop or closed-loop systems. An error analysis technique is developed, and is implemented by a digital computer program that is based on a digital simulation of the system. As an output the program gives the programing form required for minimum system quantization errors (either maximum of rms errors), and the maximum and rms errors that appear in the system output for a given bit configuration. The program can be integrated into existing digital simulations of a system.

Orbit classification in an equal-mass non-spinning binary black hole pseudo-Newtonian system

NASA Astrophysics Data System (ADS)

Zotos, Euaggelos E.; Dubeibe, Fredy L.; González, Guillermo A.

2018-07-01

The dynamics of a test particle in a non-spinning binary black hole system of equal masses is numerically investigated. The binary system is modelled in the context of the pseudo-Newtonian circular restricted three-body problem, such that the primaries are separated by a fixed distance and move in a circular orbit around each other. In particular, the Paczyński-Wiita potential is used for describing the gravitational field of the two non-Newtonian primaries. The orbital properties of the test particle are determined through the classification of the initial conditions of the orbits, using several values of the Jacobi constant, in the Hill's regions of possible motion. The initial conditions are classified into three main categories: (i) bounded, (ii) escaping, and (iii) displaying close encounters. Using the smaller alignment index chaos indicator, we further classify bounded orbits into regular, sticky, or chaotic. To gain a complete view of the dynamics of the system, we define grids of initial conditions on different types of two-dimensional planes. The orbital structure of the configuration plane, along with the corresponding distributions of the escape and collision/close encounter times, allow us to observe the transition from the classical Newtonian to the pseudo-Newtonian regime. Our numerical results reveal a strong dependence of the properties of the considered basins with the Jacobi constant as well as with the Schwarzschild radius of the black holes.

On the Pre-impact Orbital Evolution of 2018 LA, Parent Body of the Bright Fireball Observed Over Botswana on 2018 June 2

NASA Astrophysics Data System (ADS)

de la Fuente Marcos, Carlos; de la Fuente Marcos, Raúl

2018-06-01

On 2018 June 2, meteoroid 2018 LA became the third natural body ever to be observed before entering our atmosphere ---small asteroids 2014 AA and 2008 TC3 had stricken the Earth on 2014 January 2 and 2008 October 7, respectively. Here, we explore the pre-impact orbital evolution of 2018 LA and investigate the possible presence of known NEOs moving in similar orbits using N-body simulations and the D-criteria. We identify several objects moving in orbits similar to that of 2018 LA and focus on three of them: (454100) 2013 BO73, which is the largest of the group and a PHA, 2016 LR, and 2018 BA5, which follows a path very close to that of 2018 LA in terms of semimajor axis, eccentricity, and inclination. All these objects could be part of a dynamical grouping and their orbital evolution is rather chaotic, experiencing close encounters with Venus, the Earth-Moon system, and Mars. NEO encounters take place at the node and, on the short-term, the relative positions of our planet in its orbit around the Sun repeat every year. Besides the bright fireball observed over Botswana on 2018 June 2, three other bolides were observed early in June in recent years: Crete on 2002 June 6, Washington State on 2004 June 3, and Reisadalen on 2007 June 7.

Searching for co-orbital planets by combining transit and radial-velocity measurements

NASA Astrophysics Data System (ADS)

Robutel, p.; Leleu, A.; Correia, A.; Lillo-Box, J.

2017-09-01

Co-orbital planetary systems consist of two planets orbiting with the same period a central star. If co-orbital bodies are common in the solar system and are also a natural output of planetary formation models, so far none have been found in extrasolar systems. This lack may be due to observational biases, since the main detection methods are unable to spot co-orbital companions when they are small or near the Lagrangian equilibrium points. We propose a simple method, based on an idea from Ford & Gaudi (2006), that allows the detection of co-orbital companions, and relies on a single parameter proportional to the mass ratio of the two planets. This method is applied to archival radial velocity data of 46 close-in transiting planets among which a few are strong candidates to harbor a co-orbital companion.

JEM module

NASA Image and Video Library

2008-06-06

S124-E-006734 (6 June 2008) --- One of a series of digital still images documenting the Japanese Experiment Module, or JEM, also called Kibo, in its new home on the International Space Station, this view depicts Kibo's exterior, backdropped by solar array panels for the orbital outpost and one of its trusses.

JEM module

NASA Image and Video Library

2008-06-06

S124-E-006735 (6 June 2008) --- One of a series of digital still images documenting the Japanese Experiment Module, or JEM, also called Kibo, in its new home on the International Space Station, this view depicts Kibo's exterior, backdropped by solar array panels for the orbital outpost and one of its trusses.

Particle-Gas Temperature Differentials Resulting from Time-Dependent Radiative-Conductive Heat Flux Divergences in the Tenuous Dust-Laden Atmosphere of Mars.

DTIC Science & Technology

1987-01-01

The obliquity (inclination of the Martian equator to the Martian orbital plane) is 23059, very close to Earth’s value of 230271. The orbit of Mars...is inclined 1051’ to the ecliptic . The eccer.;ricity of the orbit (the ratio of the -iistanc, Detween the foci of the elliptical orbit 04.. I A m 1~0...and the major axis of the ellipse) is 0.0934, more .’ than five times the value for Earth (0.0167) (Pasachoff, 1979). The obliquity varies by 13

A Survey of Exoplanetary Spin-Orbit Angles

NASA Astrophysics Data System (ADS)

Winn, Josh

2010-02-01

Are the orbits of exoplanets aligned with the spin axes of their parent stars? One might expect a close alignment, but some of the proposed migration mechanisms predict otherwise. Indeed at least 4 planets with strongly tilted orbits are now known, including the first case of a retrograde or polar orbit. This raises the questions of how commonly misalignments occur, and which types of planets have them. We request 10 half-nights with Keck/HIRES spread over 2010A and 2010B, to measure spin-orbit angles for 9 exoplanets spanning a range of masses, periods, and eccentricities. Our measurement is based on the Rossiter-McLaughlin effect: the anomalous Doppler shift observed during planetary transits.

A Survey of Exoplanetary Spin-Orbit Angles

NASA Astrophysics Data System (ADS)

Winn, Josh

2010-08-01

Are the orbits of exoplanets aligned with the spin axes of their parent stars? One might expect a close alignment, but some of the proposed migration mechanisms predict otherwise. Indeed at least 4 planets with strongly tilted orbits are now known, including the first case of a retrograde or polar orbit. This raises the questions of how commonly misalignments occur, and which types of planets have them. We request 4 half-nights with Keck/HIRES spread over the 2010B semester, to measure spin-orbit angles for 4 exoplanets spanning a range of masses, periods, and eccentricities. Our measurement is based on the Rossiter-McLaughlin effect: the anomalous Doppler shift observed during planetary transits.

Closeup oblique view of the aft fuselage of the Orbiter ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Close-up oblique view of the aft fuselage of the Orbiter Discovery looking forward and port as the last Space Shuttle Main Engine is being removed, it can be seen on the left side of the image frame. Note that one of the Orbiter Maneuvering System/ Reaction Control System has been removed while one of them remains. Also note that the body flap, below the engine positions has a protective covering to prevent damage to the High-temperature Reusable Surface Insulation tiles. This image was taken inside the Orbiter Processing Facility at Kennedy Space Center. - Space Transportation System, Orbiter Discovery (OV-103), Lyndon B. Johnson Space Center, 2101 NASA Parkway, Houston, Harris County, TX

Closeup oblique view of the aft fuselage of the Orbiter ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Close-up oblique view of the aft fuselage of the Orbiter Discovery looking forward and starboard as the last Space Shuttle Main Engine is being removed, it can be seen on the right side of the image frame. Note that one of the Orbiter Maneuvering System/ Reaction Control System has been removed while one of them remains. Also note that the body flap, below the engine positions has a protective covering to prevent damage to the High-temperature Reusable Surface Insulation tiles. This image was taken inside the Orbiter Processing Facility at Kennedy Space Center. - Space Transportation System, Orbiter Discovery (OV-103), Lyndon B. Johnson Space Center, 2101 NASA Parkway, Houston, Harris County, TX

Lissajous Orbit Control for the Deep Space Climate Observatory Sun-Earth L1 Libration Point Mission

NASA Technical Reports Server (NTRS)

Roberts, Craig; Case, Sarah; Reagoso, John

2015-01-01

DSCOVR Lissajous Orbit sized such that orbit track never extends beyond 15 degrees from Earth-Sun line (as seen from Earth). Requiring delta-V maneuvers, control orbit to obey a Solar Exclusion Zone (SEZ) cone of half-angle 4 degrees about the Earth-Sun line. Spacecraft should never be less than 4 degrees from solar center as seen from Earth. Following Lissajous Orbit Insertion (LOI), DSCOVR should be in an opening phase that just skirts the 4-degree SEZ. Maximizes time to the point where a closing Lissajous will require avoidance maneuvers to keep it out of the SEZ. Station keeping maneuvers should take no more than 15 minutes.

Orbital tuberculosis in childhood with intracranial extension: a case report.

PubMed

Tuli, Navneet

2010-01-28

The common causes of orbital masses in pediatric age group include pseudotumour, lymphomas, hemangioma and dermoid cyst. Orbital tuberculosis is rare especially in children. We report a case of 5 year old child who presented with proptosis and gross diminution of vision due to orbital tuberculoma. Ocular examination of the left eye revealed proptosis with the eyeball displaced downwards and forwards. Vision was counting finger close to face. CT Scan showed an extraconal soft tissue mass along posteromedial side of left orbit with lateral displacement of medial rectus muscle. On antitubercular treatment, proptosis regressed and visual recovery was observed over a period of six month vision, in the left eye at the last followup was 20/30.

Effect of the stellar spin history on the tidal evolution of close-in planets

NASA Astrophysics Data System (ADS)

Bolmont, E.; Raymond, S. N.; Leconte, J.; Matt, S. P.

2012-08-01

Context. The spin rate of stars evolves substantially during their lifetime, owing to the evolution of their internal structure and to external torques arising from the interaction of stars with their environments and stellar winds. Aims: We investigate how the evolution of the stellar spin rate affects, and is affected by, planets in close orbits via star-planet tidal interactions. Methods: We used a standard equilibrium tidal model to compute the orbital evolution of single planets orbiting both Sun-like stars and very low-mass stars (0.1 M⊙). We tested two stellar spin evolution profiles, one with fast initial rotation (1.2 day rotation period) and one with slow initial rotation (8 day period). We tested the effect of varying the stellar and planetary dissipations, and the planet's mass and initial orbital radius. Results: For Sun-like stars, the different tidal evolution between initially rapidly and slowly rotating stars is only evident for extremely close-in gas giants orbiting highly dissipative stars. However, for very low-mass stars the effect of the initial rotation of the star on the planet's evolution is apparent for less massive (1 M⊕) planets and typical dissipation values. We also find that planetary evolution can have significant effects on the stellar spin history. In particular, when a planet falls onto the star, it can cause the star to spin up. Conclusions: Tidal evolution allows us to differentiate between the early behaviors of extremely close-in planets orbiting either a rapidly rotating star or a slowly rotating star. The early spin-up of the star allows the close-in planets around fast rotators to survive the early evolution. For planets around M-dwarfs, surviving the early evolution means surviving on Gyr timescales, whereas for Sun-like stars the spin-down brings about late mergers of Jupiter planets. In the light of this study, we can say that differentiating one type of spin evolution from another given the present position of planets can be very tricky. Unless we can observe some markers of former evolution, it is nearly impossible to distinguish the two very different spin profiles, let alone intermediate spin-profiles. Nevertheless, some conclusions can still be drawn about statistical distributions of planets around fully convective M-dwarfs. If tidal evolution brings about a merger late in the stellar history, it can also entail a noticeable acceleration of the star at late ages, so that it is possible to have old stars that spin rapidly. This raises the question of how the age of stars can be more tightly constrained.

PROPERTIES OF THE CLOSE-IN TERTIARY IN THE QUADRUPLE SYSTEM V401 CYG

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

Zhu, L.-Y.; Qian, S.-B.; Zhou, X.

2013-08-01

V401 Cyg is a quadruple system in which the spectroscopic signature of a close-in tertiary and a distant visual companion star were reported. Orbital properties of the close-in companion should provide valuable information on the formation of close binaries and stellar dynamical interaction. By analyzing new times of minimum light together with those collected from the literature, we discovered that the observed-calculated (O - C) curve of V401 Cyg shows a cyclic change with a short period of 3.5 yr and a semi-amplitude of 0.00436 days while it undergoes an upward parabolic variation. Those photoelectric and CCD data covered moremore » than two cycles and were analyzed for the light-travel time effect via the presence of the tertiary companion. The mass of the third body was determined to be M{sub 3}sin i' = 0.65({+-} 0.08) M{sub Sun }, which is close to the value estimated from the spectroscopic data (M{sub 3} {approx} 0.64 M{sub Sun }). This reveals that the orbital inclination of the tertiary was about i' {approx} 90 Degree-Sign , indicating that the contact components of V401 Cyg have the possibility of being eclipsed by the tertiary at an orbital distance of about 3.0 AU, and it may be a triply eclipsing hierarchical triple system. The upward parabolic change indicates a period increase at a rate of (P-dot{sub 2} = 1.5 x 10{sup -7} revealing a mass transfer from the secondary to the primary (M-dot{sub 2} = 5.9 x 10{sup -8} M{sub Sun} yr{sup -1}). This is consistent with the predictions of the theory of thermal relaxation oscillation (TRO) suggesting that V401 Cyg is undergoing an expanding-orbit stage in the TRO cycles.« less

Digital evaluation of orbital development in chinese children with congenital microphthalmia.

PubMed

Yang, Guang; Wang, Jing; Chang, Qinglin; Wang, Zhenchang; Geng, Yulei; Li, Dongmei

2012-09-01

To evaluate the asymmetry of bilateral orbital development in Chinese children with congenital microphthalmia and to provide a criterion for tailoring treatment timing and therapy. Retrospective cohort study. By combining multisection helical computerized tomography imaging with a computer-aided design system, we measured 38 children between 0 and 6 years of age with congenital microphthalmia and 70 normal children of the same age group. Variables were measured, including orbital volume, depth, width, and height and eyeball volume. Displacement of the orbital rims was calculated by mirroring the unaffected orbit across the midsagittal plane of body. Significant differences were observed between the orbital volume, eyeball volume, orbital width, and orbital height of the affected and unaffected sides of children with congenital microphthalmia (P < .001). The difference between the orbital depth of the affected and unaffected sides was not significant (P = .055). Growth of the inferior and lateral rims retarded by an average of 3 mm, whereas that of the medial and superior rims retarded by less than 1 mm. The amount of decrease in orbital volume of children with congenital microphthalmia is related to the severity of the disease (decrease in size of the eye), rather than to age. Retarded orbital development is evident primarily in the inferior and lateral rims, correlating mostly with zygomatic and then maxilla and frontal bone. The growth of the affected orbit slows down or even stagnates by 3 years of age. Intervention therapy before 3 years of age was critical. Copyright © 2012 Elsevier Inc. All rights reserved.

Lazy orbits: An optimization problem on the sphere

NASA Astrophysics Data System (ADS)

Vincze, Csaba

2018-01-01

Non-transitive subgroups of the orthogonal group play an important role in the non-Euclidean geometry. If G is a closed subgroup in the orthogonal group such that the orbit of a single Euclidean unit vector does not cover the (Euclidean) unit sphere centered at the origin then there always exists a non-Euclidean Minkowski functional such that the elements of G preserve the Minkowskian length of vectors. In other words the Minkowski geometry is an alternative of the Euclidean geometry for the subgroup G. It is rich of isometries if G is "close enough" to the orthogonal group or at least to one of its transitive subgroups. The measure of non-transitivity is related to the Hausdorff distances of the orbits under the elements of G to the Euclidean sphere. Its maximum/minimum belongs to the so-called lazy/busy orbits, i.e. they are the solutions of an optimization problem on the Euclidean sphere. The extremal distances allow us to characterize the reducible/irreducible subgroups. We also formulate an upper and a lower bound for the ratio of the extremal distances. As another application of the analytic tools we introduce the rank of a closed non-transitive group G. We shall see that if G is of maximal rank then it is finite or reducible. Since the reducible and the finite subgroups form two natural prototypes of non-transitive subgroups, the rank seems to be a fundamental notion in their characterization. Closed, non-transitive groups of rank n - 1 will be also characterized. Using the general results we classify all their possible types in lower dimensional cases n = 2 , 3 and 4. Finally we present some applications of the results to the holonomy group of a metric linear connection on a connected Riemannian manifold.

Quantifying uncertainty of measuring gully morphological evolution with close-range digital photogrammetry

USDA-ARS?s Scientific Manuscript database

Measurement of geomorphic change may be of interest to researchers and practitioners in a variety of fields including geology, geomorphology, hydrology, engineering, and soil science. Landscapes are often represented by digital elevation models. Surface models generated of the same landscape over a ...

Families of periodic orbits in Hill's problem with solar radiation pressure: application to Hayabusa 2

NASA Astrophysics Data System (ADS)

Giancotti, Marco; Campagnola, Stefano; Tsuda, Yuichi; Kawaguchi, Jun'ichiro

2014-11-01

This work studies periodic solutions applicable, as an extended phase, to the JAXA asteroid rendezvous mission Hayabusa 2 when it is close to target asteroid 1999 JU3. The motion of a spacecraft close to a small asteroid can be approximated with the equations of Hill's problem modified to account for the strong solar radiation pressure. The identification of families of periodic solutions in such systems is just starting and the field is largely unexplored. We find several periodic orbits using a grid search, then apply numerical continuation and bifurcation theory to a subset of these to explore the changes in the orbit families when the orbital energy is varied. This analysis gives information on their stability and bifurcations. We then compare the various families on the basis of the restrictions and requirements of the specific mission considered, such as the pointing of the solar panels and instruments. We also use information about their resilience against parameter errors and their ground tracks to identify one particularly promising type of solution.

A high capacity data recording device based on a digital audio processor and a video cassette recorder.

PubMed

Bezanilla, F

1985-03-01

A modified digital audio processor, a video cassette recorder, and some simple added circuitry are assembled into a recording device of high capacity. The unit converts two analog channels into digital form at 44-kHz sampling rate and stores the information in digital form in a common video cassette. Bandwidth of each channel is from direct current to approximately 20 kHz and the dynamic range is close to 90 dB. The total storage capacity in a 3-h video cassette is 2 Gbytes. The information can be retrieved in analog or digital form.

A high capacity data recording device based on a digital audio processor and a video cassette recorder.

PubMed Central

Bezanilla, F

1985-01-01

A modified digital audio processor, a video cassette recorder, and some simple added circuitry are assembled into a recording device of high capacity. The unit converts two analog channels into digital form at 44-kHz sampling rate and stores the information in digital form in a common video cassette. Bandwidth of each channel is from direct current to approximately 20 kHz and the dynamic range is close to 90 dB. The total storage capacity in a 3-h video cassette is 2 Gbytes. The information can be retrieved in analog or digital form. PMID:3978213

The Precession Index, A Nonlinear Energy Balance Model, And Seversmith Psychroterms

NASA Technical Reports Server (NTRS)

Rubincam, David Parry

2004-01-01

An important component of Milankovitch's astronomical theory of climate change is the precession index. The precession index, along with the Earth's tilt and orbital eccentricity, are believed to be the major controlling factors of climate change in the last few million years. The precession index is e sin omega(sub s) where e is the Earth's orbital eccentricity and omega(sub s) measures how close the Sun is to the Earth at midsummer. When omega(sub s) = 90deg the Sun is close to the Earth during northern summer, and at 270deg it is far from the Earth during northern summer. The precession index varies with time, because both the eccentricity e and the parameter omega(sub s) are constantly changing due to disturbances in the Earth's orbit by other planets, and due to the precession of the Earth, The change is largely periodic, with a period of about 23,000 years.

Spacecraft exploration of Phobos and Deimos

NASA Astrophysics Data System (ADS)

Duxbury, Thomas C.; Zakharov, Alexander V.; Hoffmann, Harald; Guinness, Edward A.

2014-11-01

We review the previous exploration of Phobos and Deimos by spacecraft. The first close-up images of Phobos and Deimos were obtained by the Mariner 9 spacecraft in 1971, followed by much image data from the two Viking orbiters at the end of the 70s, which formed the basis for early Phobos and Deimos shape and dynamic models. The Soviet Phobos 2 spacecraft came within 100 km of landing on Phobos in 1988. Mars Global Surveyor (1996-2006) and Mars Reconnaissance Orbiter (since 2005) made close-up observations of Phobos on several occasions. Mars Express (since 2003) in its highly elliptical orbit is currently the only spacecraft to make regular Phobos encounters and has returned large volumes of science data for this satellite. Landers and rovers on the ground (Viking Landers, Mars Pathfinder, MER rovers, MSL rover) frequently made observations of Phobos, Deimos and their transits across the solar disk.

Baggie: A unique solution to an orbiter icing problem

NASA Technical Reports Server (NTRS)

Walkover, L. J.

1982-01-01

The orbiter icing problem, located in two lower surface mold line cavities, was solved. These two cavities are open during Shuttle ground operations and ascent, and are then closed after orbit insertion. If not protected, these cavities may be coated with ice, which may be detrimental to the adjacent thermal protection system (TPS) tiles if the ice breaks up during ascent, and may hinder the closing of the cavity doors if the ice does not break up. The problem of ice in these cavities was solved by the use of a passive mechanism called baggie, which is purge curtain used to enclose the cavity and is used in conjunction with gaseous nitrogen as the local purge gas. The baggie, the final solution, is unique in its simplicity, but its design and development were not. The final baggie design and its development testing are discussed. Also discussed are the baggie concepts and other solutions not used.

Closed-channel contribution in the BCS-BEC crossover regime of an ultracold Fermi gas with an orbital Feshbach resonance

NASA Astrophysics Data System (ADS)

Mondal, S.; Inotani, D.; Ohashi, Y.

2018-03-01

We theoretically investigate strong-coupling properties of an ultracold Fermi gas with an orbital Feshbach resonance (OFR). Including tunable pairing interaction associated with an OFR within the framework of the strong-coupling theory developed by Nozières and Schmitt-Rink (NSR), we examine the occupation of the closed channel. We show that, although the importance of the closed channel is characteristic of the system with an OFR, the occupation number of the closed channel is found to actually be very small at the superfluid phase transition temperature T c, in the whole BCS (Bardeen-Cooper-Schrieffer)-BEC (Bose-Einstein condensation) crossover region, when we use the scattering parameters for an ultracold 173Yb Fermi gas. The occupation of the closed channel increases with increasing the temperature above T c, which is more remarkable for a stronger pairing interaction. We also present a prescription to remove effects of an experimentally inaccessible deep bound state from the NSR formalism, which we meet when we theoretically deal with a 173Yb Fermi gas with an OFR.

KSC-04PD-1810

NASA Technical Reports Server (NTRS)

2004-01-01

KENNEDY SPACE CENTER, FLA. In the Orbiter Processing Facility, from left, United Space Alliance workers Loyd Turner, Craig Meyer and Erik Visser prepare to conduct a fit check of an External Tank (ET) digital still camera in the right-hand liquid oxygen umbilical well on Space Shuttle Atlantis. NASA is pursuing use of the camera, beginning with the Shuttles Return To Flight, to obtain and downlink high-resolution images of the ET following separation of the ET from the orbiter after launch. The Kodak camera will record 24 images, at one frame per 1.5 seconds, on a flash memory card. After orbital insertion, the crew will transfer the images from the memory card to a laptop computer. The files will then be downloaded through the Ku-band system to the Mission Control Center in Houston for analysis.

KSC-04PD-1811

NASA Technical Reports Server (NTRS)

2004-01-01

KENNEDY SPACE CENTER, FLA. In the Orbiter Processing Facility, from left, United Space Alliance workers Loyd Turner, Craig Meyer and Erik Visser conduct a fit check of an External Tank (ET) digital still camera in the right-hand liquid oxygen umbilical well on Space Shuttle Atlantis. NASA is pursuing use of the camera, beginning with the Shuttles Return To Flight, to obtain and downlink high-resolution images of the ET following separation of the ET from the orbiter after launch. The Kodak camera will record 24 images, at one frame per 1.5 seconds, on a flash memory card. After orbital insertion, the crew will transfer the images from the memory card to a laptop computer. The files will then be downloaded through the Ku-band system to the Mission Control Center in Houston for analysis.

KSC-04pd1811

NASA Image and Video Library

2004-09-17

KENNEDY SPACE CENTER, FLA. - In the Orbiter Processing Facility, from left, United Space Alliance workers Loyd Turner, Craig Meyer and Erik Visser conduct a fit check of an External Tank (ET) digital still camera in the right-hand liquid oxygen umbilical well on Space Shuttle Atlantis. NASA is pursuing use of the camera, beginning with the Shuttle’s Return To Flight, to obtain and downlink high-resolution images of the ET following separation of the ET from the orbiter after launch. The Kodak camera will record 24 images, at one frame per 1.5 seconds, on a flash memory card. After orbital insertion, the crew will transfer the images from the memory card to a laptop computer. The files will then be downloaded through the Ku-band system to the Mission Control Center in Houston for analysis.

KSC-04pd1810

NASA Image and Video Library

2004-09-17

KENNEDY SPACE CENTER, FLA. - In the Orbiter Processing Facility, from left, United Space Alliance workers Loyd Turner, Craig Meyer and Erik Visser prepare to conduct a fit check of an External Tank (ET) digital still camera in the right-hand liquid oxygen umbilical well on Space Shuttle Atlantis. NASA is pursuing use of the camera, beginning with the Shuttle’s Return To Flight, to obtain and downlink high-resolution images of the ET following separation of the ET from the orbiter after launch. The Kodak camera will record 24 images, at one frame per 1.5 seconds, on a flash memory card. After orbital insertion, the crew will transfer the images from the memory card to a laptop computer. The files will then be downloaded through the Ku-band system to the Mission Control Center in Houston for analysis.

Autonomous space processor for orbital debris

NASA Technical Reports Server (NTRS)

1990-01-01

This work continues to develop advanced designs toward the ultimate goal of a Get Away Special to demonstrate economical removal of orbital debris using local resources in orbit. The fundamental technical feasibility was demonstrated in 1988 through theoretical calculations, quantitative computer animation, a solar focal point cutter, a robotic arm design, and a subscale model. Last year improvements were made to the solar cutter and the robotic arm. Also performed last year was a mission analysis that showed the feasibility of retrieving at least four large (greater than 1500-kg) pieces of debris. Advances made during this reporting period are the incorporation of digital control with the existing placement arm, the development of a new robotic manipulator arm, and the study of debris spin attenuation. These advances are discussed here.

Virtual Libraries: Interactive Support Software and an Application in Chaotic Models.

ERIC Educational Resources Information Center

Katsirikou, Anthi; Skiadas, Christos; Apostolou, Apostolos; Rompogiannakis, Giannis

This paper begins with a discussion of the characteristics and the singularity of chaotic systems, including dynamic systems theory, chaotic orbit, fractals, chaotic attractors, and characteristics of chaotic systems. The second section addresses the digital libraries (DL) concept and the appropriateness of chaotic models, including definition and…

Characterization of Transiting Exoplanets by Way of Differential Photometry

ERIC Educational Resources Information Center

Cowley, Michael; Hughes, Stephen

2014-01-01

This paper describes a simple activity for plotting and characterizing the light curve from an exoplanet transit event by way of differential photometry analysis. Using free digital imaging software, participants analyse a series of telescope images with the goal of calculating various exoplanet parameters, including size, orbital radius and…

MS Lonchakov waves while standing in the interdeck hatch of Endeavour

NASA Image and Video Library

2001-04-21

S100-E-5073 (21 April 2001) --- Cosmonaut Yuri V. Lonchakov, mission specialist representing Rosaviakosmos, waves to a crew mate while translating through the passageway between the middeck and flight deck onboard the Earth-orbiting Space Shuttle Endeavour. The image was recorded with a digital still camera.

Forrester types on laptop computer in the orbiter middeck

NASA Image and Video Library

2001-08-13

STS105-E-5158 (13 August 2001) --- Astronaut Patrick G. Forrester, STS-105 mission specialist, inputs data on a laptop computer on the mid deck of the Space Shuttle Discovery, which is currently docked to the International Space Station (ISS). The image was recorded with a digital still camera.

47 CFR 11.47 - Optional use of other communications methods and systems.

Code of Federal Regulations, 2014 CFR

2014-10-01

...) Analog and digital broadcast stations may additionally transmit EAS messages through other communications... providers, such as low earth orbiting satellites, that wish to participate in the EAS may contact the FCC's... 47 Telecommunication 1 2014-10-01 2014-10-01 false Optional use of other communications methods...

47 CFR 11.47 - Optional use of other communications methods and systems.

Code of Federal Regulations, 2012 CFR

2012-10-01

...) Analog and digital broadcast stations may additionally transmit EAS messages through other communications... providers, such as low earth orbiting satellites, that wish to participate in the EAS may contact the FCC's... 47 Telecommunication 1 2012-10-01 2012-10-01 false Optional use of other communications methods...

47 CFR 11.47 - Optional use of other communications methods and systems.

Code of Federal Regulations, 2010 CFR

2010-10-01

...) Analog and digital broadcast stations may additionally transmit EAS messages through other communications... providers, such as low earth orbiting satellites, that wish to participate in the EAS may contact the FCC's... 47 Telecommunication 1 2010-10-01 2010-10-01 false Optional use of other communications methods...

47 CFR 11.47 - Optional use of other communications methods and systems.

Code of Federal Regulations, 2011 CFR

2011-10-01

...) Analog and digital broadcast stations may additionally transmit EAS messages through other communications... providers, such as low earth orbiting satellites, that wish to participate in the EAS may contact the FCC's... 47 Telecommunication 1 2011-10-01 2011-10-01 false Optional use of other communications methods...

47 CFR 11.47 - Optional use of other communications methods and systems.

Code of Federal Regulations, 2013 CFR

2013-10-01

...) Analog and digital broadcast stations may additionally transmit EAS messages through other communications... providers, such as low earth orbiting satellites, that wish to participate in the EAS may contact the FCC's... 47 Telecommunication 1 2013-10-01 2013-10-01 false Optional use of other communications methods...

Preliminary Planning for NEAR's Low-Altitude Operations at 433 Eros

NASA Technical Reports Server (NTRS)

Antreasian, P. G.; Helfrich, C. L.; Miller, J. K.; Owen, W. M.; Williams, B. G.; Yeomans, D. K.; Scheeres, D. J.; Dunham, D. W.; Farquhar, R. W.; McAdams, J. V.

1999-01-01

On February 14, 2000, an orbit insertion burn will place NASA's Near Earth Asteroid Rendezvous (NEAR) spacecraft (S/C) into orbit around asteroid 433 Eros. NEAR will initially orbit Eros with distances ranging from 500 to 100 km in order to characterize the shape, gravity and spin of Eros. Once the physical parameters of Eros are determined reasonably well, the plan is to establish an orbit of the NEAR S/C with increasingly lower altitudes as the one year orbital mission progresses while further characterizing the gravity and shape of Eros. Towards the end of the NEAR mission, after the shape, gravity and spin of Eros have been well characterized, the scientific interest of obtaining very close observations (< 5 km) can be realized. The navigation during this phase relies on a combination of NASA's Deep Space Network (DSN) radio metric tracking, laser ranging (LIDAR) data from the S/C to the surface of Eros, and onboard optical imaging of landmarks on Eros. This paper will provide preliminary plans for mission design and navigation during the last two months of the orbit phase, where several close passes to the surface will be incorporated to enhance the science return. The culmination of these close passes will result in the eventual landing of the S/C on the surface of Eros. Several considerations for these plans are given by Antreasian, et at. [1998]. The objective for the end of the mission will be to land the S/C autonomously using the surface relative information obtained from the onboard LIDAR instrument. The goal will be to soft land the S/C in such a way as to keep it operational. With the use of an onboard LIDAR landing algorithm as discussed by Antreasian et at. [1998], it is believed that the S/C impact velocity can be kept well under 7 m/s which is a requirement for allowing the S/C to remain operational.

NEA impactors: what direction to they come from?

NASA Astrophysics Data System (ADS)

Harris, Alan

2018-04-01

One might expect, if Earth-crossing NEAs are "thermalized" by prior close scattering encounters with the Earth, that final impact trajectories would be isotropic in direction. But orbital perturbations and other sources of entry and exit to the Earth-crossing zone are faster acting that thermalization, so the actual distribution of impacting orbits is quite anisotropic. I have studied impactor directions by adjusting the orbits of known Earth-crossing PHAs slightly to put them on intersecting orbits and then computed the direction of approach to the Earth. This arguably suffers from "looking under the lamp post", since NEAs are mostly discovered close to the opposition direction, so I also took the distribution of NEA orbits recently derived by Granvik and others and extracted, from a set of 100,000 synthetic orbits they provided, a subset of Earth-crossing PHAs and similarly adjusted them to be intersecting orbits. This should represent an unbiased set of orbits. I then weighted the impact directions by the individual Opik impact probability to obtain a distribution of impact directions weighted by actual impact probabilities. The result was that more than 40% of incoming trajectories clustered within 60 degrees of the opposition direction, and a similar fraction come from within 60 degrees of the solar direction. Thus ~80% of impactors come from only about 1/3 of the sky area, with almost none coming from 60-120 degrees solar elongation. The message is that existing ground-based surveys can hardly be improved upon by greater sky coverage with respect to detecting "death plunge" objects, and even space-based instruments offer very little improvement due to the very low solar elongation of most objects approaching from the solar direction.

Proceedings of the Space Surveillance Workshop (11th) Held in Lexington, Massachusetts on 30 March-1 April 1993. Volume 1

DTIC Science & Technology

1993-04-01

are so close together, there is a great deal of mistagged metric data from the SPACETRACK sensors on these objects. The resulting orbital element sets ...including an attempt to combine U.S. Space Command element sets for each Lageos-2 related object in orbit with DSN angle data to determine the actual...Predict error at next observation -Maintain track to minimize reacquistion load -Estimate orbital element sets -Update time for next observation

Possibility of exchange of a rectilinear three-body system with zero energy

NASA Astrophysics Data System (ADS)

Koda, Eiji

The possibility of exchange for a rectilinear three-body system with zero energy is examined by introducing regularized coordinates which are closely related to McGehee's (1974) coordinates. It is shown that all of the HE(-)-HE(+) orbits are of exchange type in a critical system whose orbits of parabolic-parabolic escape type experience odd times of binary collision. No exchange occurs in critical systems whose orbits of parabolic-parabolic escape type experience even times of binary collision.

Closeup oblique view of the forward and starboard sides of ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Close-up oblique view of the forward and starboard sides of the Orbiter Discovery in the Vehicle Assembly Building at NASA's Kennedy Space Center. The view shows the void created by the removal of the Forward Reaction Control System Module. The void has a clear flexible covering to maintain positive pressure in the void to minimize foreign object contamination possibilities in the orbiter. - Space Transportation System, Orbiter Discovery (OV-103), Lyndon B. Johnson Space Center, 2101 NASA Parkway, Houston, Harris County, TX

Closeup view of the forward and starboard sides of the ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Close-up view of the forward and starboard sides of the Orbiter Discovery in the Vehicle Assembly Building at NASA's Kennedy Space Center. The view shows the void created by the removal of the Forward Reaction Control System Module. The void has a clear flexible covering to maintain positive pressure in the void to minimize foreign object contamination possibilities in the orbiter. - Space Transportation System, Orbiter Discovery (OV-103), Lyndon B. Johnson Space Center, 2101 NASA Parkway, Houston, Harris County, TX

Sentry: An Automated Close Approach Monitoring System for Near-Earth Objects

NASA Astrophysics Data System (ADS)

Chamberlin, A. B.; Chesley, S. R.; Chodas, P. W.; Giorgini, J. D.; Keesey, M. S.; Wimberly, R. N.; Yeomans, D. K.

2001-11-01

In response to international concern about potential asteroid impacts on Earth, NASA's Near-Earth Object (NEO) Program Office has implemented a new system called ``Sentry'' to automatically update the orbits of all NEOs on a daily basis and compute Earth close approaches up to 100 years into the future. Results are published on our web site (http://neo.jpl.nasa.gov/) and updated orbits and ephemerides made available via the JPL Horizons ephemeris service (http://ssd.jpl.nasa.gov/horizons.html). Sentry collects new and revised astrometric observations from the Minor Planet Center (MPC) via their electronic circulars (MPECs) in near real time as well as radar and optical astrometry sent directly from observers. NEO discoveries and identifications are detected in MPECs and processed appropriately. In addition to these daily updates, Sentry synchronizes with each monthly batch of MPC astrometry and automatically updates all NEO observation files. Daily and monthly processing of NEO astrometry is managed using a queuing system which allows for manual intervention of selected NEOs without interfering with the automatic system. At the heart of Sentry is a fully automatic orbit determination program which handles outlier rejection and ensures convergence in the new solution. Updated orbital elements and their covariances are published via Horizons and our NEO web site, typically within 24 hours. A new version of Horizons, in development, will allow computation of ephemeris uncertainties using covariance data. The positions of NEOs with updated orbits are numerically integrated up to 100 years into the future and each close approach to any perturbing body in our dynamic model (all planets, Moon, Ceres, Pallas, Vesta) is recorded. Significant approaches are flagged for extended analysis including Monte Carlo studies. Results, such as minimum encounter distances and future Earth impact probabilities, are published on our NEO web site.

Tidal Dissipation In Rotating Low Mass Stars: Implications For The Orbital Evolution Of Close In Planets

NASA Astrophysics Data System (ADS)

Gallet, Florian; Bolmont, Emeline; Mathis, Stéphane; Charbonnel, Corinne; Amard, Louis; Alibert, Yann

2017-10-01

Close-in planets represent a large fraction of the population of confirmed exoplanets. To understand the dynamical evolution of these planets, star-planet interactions must be taken into account. In particular, the dependence of the tidal interactions on the structural parameters of the star, its rotation, and its metallicity should be treated in the models. We quantify how the tidal dissipation in the convective envelope of rotating low-mass stars evolves in time. We also investigate the possible consequences of this evolution on planetary orbital evolution. In Gallet et al. (2017) and Bolmont et al. (2017) we generalized the work of Bolmont & Mathis (2016) by following the orbital evolution of close-in planets using the new tidal dissipation predictions for advanced phases of stellar evolution and non-solar metallicity. We find that during the pre-main sequence the evolution of tidal dissipation is controlled by the evolution of the internal structure of the star through the stellar contraction. On the main-sequence tidal dissipation is strongly driven by the evolution of the surface rotation that is impacted by magnetized stellar winds braking. Finally, during the more evolved phases, the tidal dissipation sharply decreases as radiative core retreats in mass and radius towards the red-giant branch. Using an orbital evolution model, we also show that changing the metallicity leads to diUerent orbital evolutions (e.g., planets migrate farther out from an initially fast rotating metal rich star). By using this model, we qualitatively reproduced the observational trends of the population of hot Jupiters with the metallicity of their host stars. However, more work still remain to be do so as to be able to quantitatively fit our results to the observations.

First Results of the Juno Magnetometer Investigation in Jupiter's Magnetosphere

NASA Astrophysics Data System (ADS)

Connerney, Jack; Oliversen, Ronald; Espley, Jared; Kotsiaros, Stavros; Joergensen, John; Joergensen, Peter; Merano, Jose; Denver, Troelz; Benn, Mathias; Bloxham, Jeremy; Bolton, Scott; Levin, Steve

2017-04-01

The Juno spacecraft entered polar orbit about Jupiter on July 4, 2016, after a Jupiter Orbit Insertion (JOI) main engine burn lasting 35 minutes. Juno's science instruments were not powered during the critical maneuver sequence ( 5 days) but were fully operational shortly afterward. The 53.5-day capture orbit provides Juno's science instruments with the opportunity to sample the Jovian environment close up (to 1.06 Jovian radii, Rj) and in polar orbit extending to the outer reaches of the Jovian magnetosphere. Jupiter's gravity and magnetic fields will be globally mapped with unprecedented accuracy as Juno conducts a study of Jupiter's interior structure and composition, as well as the first comprehensive exploration of the polar magnetosphere. The magnetic field investigation onboard Juno is equipped with two magnetometer sensor suites, located at 10 and 12 m from the spacecraft body at the end of one of the three solar panel wings. Each contains a vector fluxgate magnetometer (FGM) sensor and a pair of co-located non-magnetic star tracker camera heads which provide accurate attitude determination for the FGM sensors. The first few periapsis passes available to date revealed an extraordinary spatial variation of the magnetic field close to the planet's surface, suggesting that Juno may be sampling the field closer to the dynamo region than widely anticipated, i.e., portending a dynamo surface extending to relatively large radial distance ( 0.9Rj?). We present the first observations of Jupiter's magnetic field obtained in close proximity to the planet, and speculate on what wonders await as more longitudes are drawn across the global map (32 polar orbits separated by <12° longitude) that the Juno mission was designed to acquire.

Space shuttle engineering and operations support. Avionics system engineering

NASA Technical Reports Server (NTRS)

Broome, P. A.; Neubaur, R. J.; Welsh, R. T.

1976-01-01

The shuttle avionics integration laboratory (SAIL) requirements for supporting the Spacelab/orbiter avionics verification process are defined. The principal topics are a Spacelab avionics hardware assessment, test operations center/electronic systems test laboratory (TOC/ESL) data processing requirements definition, SAIL (Building 16) payload accommodations study, and projected funding and test scheduling. Because of the complex nature of the Spacelab/orbiter computer systems, the PCM data link, and the high rate digital data system hardware/software relationships, early avionics interface verification is required. The SAIL is a prime candidate test location to accomplish this early avionics verification.

Communications terminal breadboard

NASA Technical Reports Server (NTRS)

1972-01-01

A baseline design is presented of a digital communications link between an advanced manned spacecraft (AMS) and an earth terminal via an Intelsat 4 type communications satellite used as a geosynchronous orbiting relay station. The fabrication, integration, and testing of terminal elements at each end of the link are discussed. In the baseline link design, the information carrying capacity of the link was estimated for both the forward direction (earth terminal to AMS) and the return direction, based upon orbital geometry, relay satellite characteristics, terminal characteristics, and the improvement that can be achieved by the use of convolutional coding/Viterbi decoding techniques.

Detail view of the interior of the flight deck looking ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Detail view of the interior of the flight deck looking forward showing the overhead control panels. Note that the flight deck windows have protective covers over them in this view. This images can be digitally stitched with image HAER No. TX-116-A-19 to expand the view to include the Commander and Pilot positions during ascent and reentry and landing. This view was taken in the Orbiter Processing Facility at the Kennedy Space Center. - Space Transportation System, Orbiter Discovery (OV-103), Lyndon B. Johnson Space Center, 2101 NASA Parkway, Houston, Harris County, TX

Advanced Communications Technology Satellite (ACTS): Design and on-orbit performance measurements

NASA Technical Reports Server (NTRS)

Gargione, F.; Acosta, R.; Coney, T.; Krawczyk, R.

1995-01-01

The Advanced Communications Technology Satellite (ACTS), developed and built by Lockheed Martin Astro space for the NASA Lewis Research Center, was launched in September 1993 on the shuttle STS 51 mission. ACTS is a digital experimental communications test bed that incorporates gigahertz bandwidth transponders operating at Ka band, hopping spot beams, on-board storage and switching, and dynamic rain fade compensation. This paper describes the ACTS enabling technologies, the design of the communications payload, the constraints imposed on the spacecraft bus, and the measurements conducted to verify the performance of the system in orbit.

STS-48 MS Buchli, eating crackers on OV-103's middeck, is captured by ESC

NASA Technical Reports Server (NTRS)

1991-01-01

STS-48 Mission Specialist (MS) James F. Buchli 'catches' goldfish snack crackers as they float in the weightless environment of the earth-orbiting Discovery, Orbiter Vehicle (OV) 103. Buchli's eating activity on the middeck was documented using the Electronic Still Camera (ESC). Crewmembers were testing the ESC as part of Development Test Objective (DTO) 648, Electronic Still Photography. The digital image was stored on a removable hard disk or small optical disk, and could be converted to a format suitable for downlink transmission. The ESC is making its initial appearance on this Space Shuttle mission.

A Radiation Hard Multi-Channel Digitizer ASIC for Operation in the Harsh Jovian Environment

NASA Technical Reports Server (NTRS)

Aslam, Shahid; Aslam, S.; Akturk, A.; Quilligan, G.

2011-01-01

In 1995, the Galileo spacecraft arrived at Jupiter to conduct follow-up experiments on pathfinder Pioneer and key Voyager discoveries especially at Io, Europa, Ganymede and Callisto. These new observations helped expand our scientific knowledge of the prominent Galilean satellites; studies revealed diversity with respect to their geology, internal structure, evolution and degree of past and present activity. Jupiter's diverse Galilean satellites, of which three are believed to harbor internal oceans, are central to understanding the habitability of icy worlds. Galileo provided for the first time compelling evidence of a near-surface global ocean on Europa. Furthermore, by understanding the Jupiter system and unraveling the history of its evolution from initial formation to the emergence of possible habitats and life, gives insight into how giant planets and their satellite systems form and evolve. Most important, new light is shed on the potential for the emergence and existence of life in icy satellite oceans. In 2009, NASA released a detailed Jupiter Europa Mission Study (EJSM) that proposed an ambitious Flagship Mission to understand more fully the satellites Europa and Ganymede within the context of the Jovian system. Key to EJSM is the NASA led Jupiter Europa Orbiter (JEO) and the ESA led Jupiter Ganymede Orbiter (JGO). JEO and JGO would execute a choreographed exploration of the Jovian system before settling into orbit around Europa and Ganymede, respectively. The National Academies Planetary Decadal Survey, 2011 has listed the NASA-led JEO as the second highest priority mission for the decade 2013-2022, and if chosen it would be launched in 2020 with arrival at Jupiter in 2025. If the JEO mission is not chosen it is anticipated that there will be opportunities in future decadal cycles. Jupiter Orbit Insertion (JOI) begins a 30-month Jovian system tour followed by nine months of science mapping after Europa Orbit Insertion (EOI) in July 2028. The orbiter will ultimately impact the surface of Europa after the mission is completed. The current JEO mission concept includes a range of instruments on the payload, to monitor dynamic phenomena (such as Io's volcanoes and Jupiters atmosphere), map the Jovian magnetosphere and its interactions with the Galilean satellites, and characterize water oceans beneath the ice shells of Europa and Ganymede. The payload includes a low mass (3.7 Kg) and low power (< 5 W) Thermal Instrument (TI) concept for measuring possible warm thermal anomalies on Europa s cold surface caused by recent (< 10,000 years) eruptive activity. Regions of anomalously high heat flow will be identified by thermal mapping using a nadir pointing, push-broom filter radiometer that provides far-IR imagery in two broad band spectral wavelength regions, 8-20 m and 20-100 m, for surface temperature measurements with better than a 2 K accuracy and a spatial resolution of 250 m/pixel obtained from a 100 Km orbit. The temperature accuracy permits a search for elevated temperatures when combined with albedo information. The spatial resolution is sufficient to resolve Europa's larger cracks and ridge axial valleys. In order to accomplish the thermal mapping, the TI uses sensitive thermopile arrays that are readout by a custom designed low-noise Multi-Channel Digitizer (MCD) ASIC that resides very close to the thermopile linear array outputs. Both the thermopile array and the MCD ASIC will need to show full functionality within the harsh Jovian radiation environment, operating at cryogenic temperatures, typically 150 K to 170 K. In the following, a radiation mitigation strategy together with a low risk Radiation-Hardened-By-Design (RHBD) methodology using commercial foundry processes is given for the design and manufacture of a MCD ASIC that will meet this challenge.

Fugitives from the Hungaria region: Close encounters and impacts with terrestrial planets

NASA Astrophysics Data System (ADS)

Galiazzo, M. A.; Bazsó, Á.; Dvorak, R.

2013-08-01

Hungaria asteroids, whose orbits occupy the region in element space between 1.78

Digital Badges in Education

ERIC Educational Resources Information Center

Gibson, David; Ostashewski, Nathaniel; Flintoff, Kim; Grant, Sheryl; Knight, Erin

2015-01-01

Digital badges provide new affordances for online educational activities and experiences. When used with points and leaderboards, a badge can become a gamification element allowing learners to compete with themselves or others, and to know how close they are to accomplishing a goal and acquiring its accompanying reputation. In this role, badges…

State-selective charge exchange in slow collisions of Si3+ ions with H atoms: A molecular state close coupling treatment*)

NASA Astrophysics Data System (ADS)

Joseph, Dwayne C.; Saha, Bidhan C.

2012-11-01

Charge transfer cross sections are calculated by employing both the quantal and semiclassical ɛ(R) molecular orbital close coupling (MOCC) approximations in the adiabatic representation and compared with other theoretical and experimental results

Formation of Close-in Super-Earths in an Evolving Disk Due to Disk Winds

NASA Astrophysics Data System (ADS)

Ogihara, Masahiro; Kokubo, Eiichiro; Suzuki, Takeru; Morbidelli, Alessandro

2018-04-01

Planets with masses larger than Mars mass undergo rapid inward migration (type I migration) in a standard protoplanetary disk. Recent magnetohydrodynamical simulations revealed the presence of magnetically-driven disk winds, which would alter the disk profile and the type I migration in the close-in region (r<1 au). We investigate orbital evolution of planetary embryos in a disk that viscously evolves under effects of magnetically-driven disk winds. The aim is to examine whether observed distributions of close-in super-Earths can be reproduced by simulations. We find that the type I migration is significantly suppressed in a disk with flat surface density profile. After planetary embryos undergo slow inward migration, they are captured in a resonant chain. The resonant chain undergoes late orbital instability during the gas depletion, leading to a non-resonant configuration. We also find that observed distributions of close-in super-Earths (e.g., period ratio, mass ratio) can be reproduced by results of simulations.

An Exoplanet Spinning Up Its Star

NASA Astrophysics Data System (ADS)

Kohler, Susanna

2016-11-01

We know that the large masses of stars govern the orbits of the planets that circle them but a large, close-in planet can also influence the rotation of its host star. A recently discovered, unusual hot Jupiter may be causing its star to spin faster than it should.Exotic PlanetsHot Jupiters are gas giants of roughly Jupiters size that orbit close in to their host stars. Though these planets are easy to detect their large sizes and frequent transits mean surveys have a good chance of catching them we havent found many of them, suggesting that planetary systems containing hot Jupiters are fairly unusual.The period-folded light curve of HATS-18, revealing the transit of the hot Jupiter HATS-18b. The period is P=0.8378 days. [Penev et al. 2016]Studying this exotic population of planets, however, can help us to better understand how gas giants form and evolve in planetary systems. New observations of hot Jupiters may also reveal how stars and close-in planets interact through radiation, gravity, and magnetic fields.The recent discovery of a transiting hot Jupiter a little over 2000 light-years away therefore presents an exciting opportunity!A Speeding GiantThe discovery of HATS-18b, a planet of roughly 2 times Jupiters mass and 1.3 times its radius, was announced in a study led by Kaloyan Penev (Princeton University). The planet was discovered using the HATSouth transit survey network, which includes instruments in Chile, Namibia, and Australia, and follow-up photometry and spectroscopy was conducted at a variety of ground-based observatories.HATS-18bs properties are particularly unusual: this hot Jupiter is zipping around its host star which is very similar to the Sun at the incredible pace of one orbit every 0.84 days. HATS-18bs orbit is more than 20 times closer to its host star than Mercurys is to the Sun, bringing it so close it nearly grazes the stars surface!Size of the planetary orbit relative to the stellar radius as a function of the stellar rotation period, for transiting planets with orbital periods shorter than 2 days and masses greater than 0.1 Jupiter masses. HATS-18b is denoted by the red star. [Penev et al. 2016]Tidal InteractionsWhat happens when a massive planet orbits this close to its star? Tidal interactions between the star and the planet cause tidal dissipation in the star, resulting in decay of the planets orbit. But there may be an additional effect of this interaction in the case of HATS-18b, the authors claim: the planet may be transferring some of its angular momentum to the star.As stars age, they should gradually spin slower as they lose angular momentum viastellar winds. But Penev and collaborators note that this exoplanets host star, HATS-18, spins roughly three times as fast asits inferred age suggests it should. The authors conclude that the angular momentum lost by the planet as its orbit shrinks is deposited in the star, causing the star to spin up.HATS-18 is an excellent laboratory for studying how very short-period planets interact with their stars in fact, Penev and collaborators have already used their observations of the system to constrain models of tidal dissipation from Sun-like stars. Additional observations of HATS-18 and other short-period systems should allow us to further test models of how planetary systems form and evolve.CitationK. Penev et al 2016 AJ 152 127. doi:10.3847/0004-6256/152/5/127

Orbital alignment of circumbinary planets that form in misaligned circumbinary discs: the case of Kepler-413b

NASA Astrophysics Data System (ADS)

Pierens, A.; Nelson, R. P.

2018-06-01

Although most of the circumbinary planets detected by the Kepler spacecraft are on orbits that are closely aligned with the binary orbital plane, the systems Kepler-413 and Kepler-453 exhibit small misalignments of ˜2.5°. One possibility is that these planets formed in a circumbinary disc whose midplane was inclined relative to the binary orbital plane. Such a configuration is expected to lead to a warped and twisted disc, and our aim is to examine the inclination evolution of planets embedded in these discs. We employed 3D hydrodynamical simulations that examine the disc response to the presence of a modestly inclined binary with parameters that match the Kepler-413 system, as a function of disc parameters and binary inclinations. The discs all develop slowly varying warps, and generally display very small amounts of twist. Very slow solid body precession occurs because a large outer disc radius is adopted. Simulations of planets embedded in these discs resulted in the planet aligning with the binary orbit plane for disc masses close to the minimum mass solar nebular, such that nodal precession of the planet was controlled by the binary. For higher disc masses, the planet maintains near coplanarity with the local disc midplane. Our results suggest that circumbinary planets born in tilted circumbinary discs should align with the binary orbit plane as the disc ages and loses mass, even if the circumbinary disc remains misaligned from the binary orbit. This result has important implications for understanding the origins of the known circumbinary planets.

Design and Technical Study of Neutrino Detector Spacecraft

NASA Technical Reports Server (NTRS)

Solomey, Niclolas

2017-01-01

A neutrino detector is proposed to be developed for use on a space probe in close orbit of the Sun. The detector will also be protected from radiation by a tungsten shield Sun shade, active veto array and passive cosmic shielding. With the intensity of solar neutrinos substantially greater in a close solar orbit than on the Earth only a small 250 kg detector is needed. It is expected that this detector and space probe studying the core of the Sun, its nuclear furnace and particle physics basic properties will bring new knowledge beyond what is currently possible for Earth bound solar neutrino detectors.

KSC-2012-5549

NASA Image and Video Library

2012-09-20

CAPE CANAVERAL, Fla. – Inside Orbiter Processing Facility-2 at NASA’s Kennedy Space Center in Florida, workers watch as the left payload bay door begins to close on space shuttle Atlantis. Both payload bay doors will be closed for the final time. The orbiter is undergoing final preparations for its transfer to the Kennedy Space Center Visitor complex targeted for November. The work is part of Transition and Retirement of the remaining shuttle. Atlantis is being prepared for public display at the visitor complex. Over the course of its 26-year career, Atlantis spent 293 days in space during 33 missions. For more information, visit http://www.nasa.gov/transition. Photo credit: NASA/Jim Grossmann

KSC-2012-5550

NASA Image and Video Library

2012-09-20

CAPE CANAVERAL, Fla. – Inside Orbiter Processing Facility-2 at NASA’s Kennedy Space Center in Florida, space shuttle Atlantis’ left payload bay door has been closed. Both payload bay doors will be closed for the final time. The orbiter is undergoing final preparations for its transfer to the Kennedy Space Center Visitor complex targeted for November. The work is part of Transition and Retirement of the remaining shuttle. Atlantis is being prepared for public display at the visitor complex. Over the course of its 26-year career, Atlantis spent 293 days in space during 33 missions. For more information, visit http://www.nasa.gov/transition. Photo credit: NASA/Jim Grossmann

Recurrence spectra of a helium atom in parallel electric and magnetic fields

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

Wang, Dehua; Department of Mathematics and Physics, Shandong Architecture and Engineering Institute, Jinan 250014, People's Republic of China; Ding, Shiliang

2003-08-01

A model potential for the general Rydberg atom is put forward, which includes not only the Coulomb interaction potential and the core-attractive potential, but also the exchange potential between the excited electron and other electrons. Using the region-splitting consistent and iterative method, we calculated the scaled recurrence spectra of the helium atom in parallel electric and magnetic fields and the closed orbits in the corresponding classical system have also been obtained. In order to remove the Coulomb singularity of the classical motion of Hamiltonian, we implement the Kustaanheimo-Stiefel transformation, which transforms the system from a three-dimensional to a four-dimensional one.more » The Fourier-transformed spectra of the helium atom has allowed direct comparison between peaks in such a plot and the scaled action values of closed orbits. Considering the exchange potential, the number of the closed orbits increased, which led to more peaks in the recurrence spectra. The results are compared with those of the hydrogen case, which shows that the core-scattered effects and the electron exchange potential play an important role in the multielectron Rydberg atom.« less

WD1145+017

NASA Astrophysics Data System (ADS)

Motta, Mario

2017-06-01

WD1145 is a 17th magnitude white dwarf star 570 light years away in Virgo, that was discovered to have a disintegrating planetoid in close orbit by Andrew Vanderburg a graduate student at Harvard CFA, while data mining the Kepler 2 mission. He contacted me to obtain transit data to elucidate the nature of its rather bizarre transit light curves. I obtained multiple observations of WD1145 over the course of a year, and found a series of complex transit light curves that could only be interpreted as a ring complex or torus in close orbit around WD1145. Combined with data from other amateur astronomers, professional observations, and satellite data it became clear that WD1145 has a small planetoid in close orbit at the Roche limit and is breaking apart forming a ring of debris material that is then raining down on the white dwarf. The surface of the star is "polluted" by heavy metals by spectroscopic data. Given that in the intense gravitational field of a white dwarf any heavy metals could not for long last on the surface, this confirms that we are tracking in real time the destruction of a small planet by its host star.

Techniques for digital enhancement of Landsat MSS data using an Apple II+ microcomputer

NASA Technical Reports Server (NTRS)

Harrington, J. A., Jr.; Cartin, K. F.

1984-01-01

The information provided by remotely sensed data collected from orbiting platforms has been useful in many research fields. Particularly convenient for evaluation are generally digital data stored on computer compatible tapes (CCT's). The major advantages of CCT's are the quality of the data and the accessibility to computer manipulation. Minicomputer systems are widely used for the required computer processing operations. However, microprocessor-related technological advances make it now possible to process CCT data with computing systems which can be obtained at a much lower price than minicomputer systems. A detailed description is provided of the design considerations of a microcomputer-based Digital Image Analysis System (DIAS). Particular attention is given to the algorithms which are incorporated for eighter edge enhancement or smoothing Landsat multispectral scanner data.

Broadcast satellite service: The international dimension

NASA Technical Reports Server (NTRS)

Samara, Noah

1991-01-01

The dawn of the 1990's has witnessed the birth of a new satellite service - satellite sound broadcasting. This new service is characterized by digital transmission at data rates up to 256 kb/s from satellites in geostationary orbit to small, low-cost, mobile and portable receivers. The satellite sound broadcasting service is a logical step beyond navigation satellite service, such as that provided by the GPS Navstar system. The mass market appeal of satellite sound broadcasting in the area of lightsat technology and low-cost digital radios has greatly facilitated the financing of this type of space service.

Computer image processing - The Viking experience. [digital enhancement techniques

NASA Technical Reports Server (NTRS)

Green, W. B.

1977-01-01

Computer processing of digital imagery from the Viking mission to Mars is discussed, with attention given to subjective enhancement and quantitative processing. Contrast stretching and high-pass filtering techniques of subjective enhancement are described; algorithms developed to determine optimal stretch and filtering parameters are also mentioned. In addition, geometric transformations to rectify the distortion of shapes in the field of view and to alter the apparent viewpoint of the image are considered. Perhaps the most difficult problem in quantitative processing of Viking imagery was the production of accurate color representations of Orbiter and Lander camera images.

Broadcast satellite service: The international dimension

NASA Astrophysics Data System (ADS)

Samara, Noah

1991-09-01

The dawn of the 1990's has witnessed the birth of a new satellite service - satellite sound broadcasting. This new service is characterized by digital transmission at data rates up to 256 kb/s from satellites in geostationary orbit to small, low-cost, mobile and portable receivers. The satellite sound broadcasting service is a logical step beyond navigation satellite service, such as that provided by the GPS Navstar system. The mass market appeal of satellite sound broadcasting in the area of lightsat technology and low-cost digital radios has greatly facilitated the financing of this type of space service.

Digital processing of orbital radar data to enhance geologic structure - Examples from the Canadian Shield

NASA Technical Reports Server (NTRS)

Masuoka, Penny M.; Harris, Jeff; Lowman, Paul D., Jr.; Blodget, Herbert W.

1988-01-01

Various digital enhancement techniques for SAR are compared using SIR-B and Seasat images of the Canadian Shield. The three best methods for enhancing geological structure were found to be: (1) a simple linear contrast stretch; (2) a mean or median low-pass filter to reduce speckle prior to edge enhancement or a K nearest-neighbor average to cosmetically reduce speckle; and (3) a modification of the Moore-Waltz (1983) technique. Three look directions were coregistered and several means of data display were investigated as means of compensating for radar azimuth biasing.

Sex determination by three-dimensional geometric morphometrics of craniofacial form.

PubMed

Chovalopoulou, Maria-Eleni; Valakos, Efstratios D; Manolis, Sotiris K

The purpose of the present study is to define which regions of the cranium, the upper-face, the orbits and the nasal are the most sexually dimorphic, by using three-dimensional geometric morphometric methods, and investigate the effectiveness of this method in determining sex from the shape of these regions. The study sample consisted of 176 crania of known sex (94 males, 82 females) belonging to individuals who lived in Greece during the 20(th) century. The three-dimensional co-ordinates of 31 ecto-cranial landmarks were digitized using a MicroScribe 3DX contact digitizer. Goodall's F-test was performed in order to compare statistical differences in shape between males and females. Generalized Procrustes Analysis (GPA) was used to obtain size and shape variables for statistical analysis. Shape, Size and Form analyses were carried out by logistic regression and discriminant function analysis. The results indicate that there are shape differences between the sexes in the upper-face and the orbits. The highest shape classification rate was obtained from the upper-face region. The centroid size of the caraniofacial and the orbital regions was smaller in females than males. Moreover, it was found that size is significant for sexual dimorphism in the upper-face region. As anticipated, the classification accuracy improves when both size and shape are combined. The findings presented here constitute a firm basis upon which further research can be conducted.

Regional Stratigraphy from Stereo Imaging near the Hypanis Fan Deposit: Marking the Extent of the Largest Delta on Mars?

NASA Astrophysics Data System (ADS)

Adler, J.; Harrison, T. N.; Bell, J. F., III; Mayer, D. P.

2017-12-01

The layered fan-shaped sedimentary deposit at the terminus of Hypanis Valles has been classified by some as an ancient delta marking the presence of a sea in Chryse Planitia, Mars. The deposit's age is estimated to be 3.6 Ga based on crater counts in the upstream catchment. We further our research on the Hypanis deposit and its relative age by analyzing digital terrain models and high-resolution orbital images of two key study areas: Lederberg crater rim and the distal island deposits. We constructed a 2 m/pix digital terrain model from our requested HiRISE stereo images (0.5 m/pix) of the Lederberg rim northwest of Hypanis, as well as a 24 m/pix digital terrain model from CTX stereo images (6 m/pix) of the island structures northeast of Hypanis. Both terrain models were controlled to MOLA shot data. We added these elevation models to a regional elevation mosaic in order to assess stratigraphy. We found that the Lederberg crater rim has polygonally fractured units, consistent with those in the plains near Hypanis, as well as an example of a distinct mildly sinuous ridge with smooth cones along its profile. We hypothesize that the formation of rounded cones in this region of Xanthe Terra near Hypanis is related to the presence of wrinkle ridges and degraded crater rims. Furthermore, we investigate whether these cones are the youngest geologic formations in the region, postdating the aqueous periods in which the delta and hydrovolcanic cones were formed. We also analyzed the elevation profiles of potential deltaic distal island deposits, and found that some islands are likely part of the main lobe of Hypanis, while others more closely match the chaos units to the east. From our analysis, it is unlikely that the large northern island was once part of the Hypanis deposit. Rather, a larger laterally continuous unit likely once draped the region post-Hypanis formation and has subsequently been eroded.

Effect of the rotation and tidal dissipation history of stars on the evolution of close-in planets

NASA Astrophysics Data System (ADS)

Bolmont, Emeline; Mathis, Stéphane

2016-11-01

Since 20 years, a large population of close-in planets orbiting various classes of low-mass stars (from M-type to A-type stars) has been discovered. In such systems, the dissipation of the kinetic energy of tidal flows in the host star may modify its rotational evolution and shape the orbital architecture of the surrounding planetary system. In this context, recent observational and theoretical works demonstrated that the amplitude of this dissipation can vary over several orders of magnitude as a function of stellar mass, age and rotation. In addition, stellar spin-up occurring during the Pre-Main-Sequence (PMS) phase because of the contraction of stars and their spin-down because of the torque applied by magnetized stellar winds strongly impact angular momentum exchanges within star-planet systems. Therefore, it is now necessary to take into account the structural and rotational evolution of stars when studying the orbital evolution of close-in planets. At the same time, the presence of planets may modify the rotational dynamics of the host stars and as a consequence their evolution, magnetic activity and mixing. In this work, we present the first study of the dynamics of close-in planets of various masses orbiting low-mass stars (from 0.6~M_⊙ to 1.2~M_⊙) where we compute the simultaneous evolution of the star's structure, rotation and tidal dissipation in its external convective envelope. We demonstrate that tidal friction due to the stellar dynamical tide, i.e. tidal inertial waves excited in the convection zone, can be larger by several orders of magnitude than the one of the equilibrium tide currently used in Celestial Mechanics, especially during the PMS phase. Moreover, because of this stronger tidal friction in the star, the orbital migration of the planet is now more pronounced and depends more on the stellar mass, rotation and age. This would very weakly affect the planets in the habitable zone because they are located at orbital distances such that stellar tide-induced migration happens on very long timescales. We also demonstrate that the rotational evolution of host stars is only weakly affected by the presence of planets except for massive companions.

Satellite tour design for the Cassini mission. [Saturn

NASA Technical Reports Server (NTRS)

Diehl, R. E.

1985-01-01

The mission design for the Cassini satellite tour of Saturn is described. The use of Titan encounters for gravity-assisted trajectory shaping to satisfy atmosphere, magnetosphere, and satellite science requirements is discussed. Three candidate satellite tours that illustrate the tradeoffs between different strategies to satisfy the science objectives are presented. Tour characteristics for a 4yr mission include at least 30 Titan encounters to provide a minimum of 90 deg orbit rotation for either a magnetotail petal orbit or noon petal orbit; evenly distributed Titan ground tracks for radar mapping coverage; at least 2 Iapetus and 1 Enceladus close flybys; inclined orbits during the first 3 yr to provide Earth and Sun occultations by Saturn and its rings; and Polar orbits during the fourth year.

The effects of heavy ion radiation on digital micromirror device performance

NASA Astrophysics Data System (ADS)

Travinsky, Anton; Vorobiev, Dmitry; Ninkov, Zoran; Raisanen, Alan D.; Pellish, Jonathan A.; Robberto, Massimo; Heap, Sara

2016-07-01

There is a pressing need in the astronomical community for space-suitable multi-object spectrometers (MOSs). Several digital micromirror device (DMD)-based prototype MOSs have been developed for ground-based observatories; however, their main use will come with deployment on a space based mission. Therefore, performance of DMDs under exoatmospheric radiation needs to be evaluated. In our previous work we demonstrated that DMDs are tolerant to heavy ion irradiation in general and calculated upset rate of 4.3 micromirrors in 24 hours in orbit for 1-megapixel device. The goal of this additional experiment was to acquire more data and therefore increase the accuracy of the predicted in-orbit micromirror upset rate. Similar to the previous experiment, for this testing 0.7 XGA DMDs were re-windowed with 2 μm thick pellicle and tested under accelerated heavy-ion radiation (with control electronics shielded from radiation) with a focus on detection of single-event upsets (SEUs). We concentrated on ions with low levels of linear energy transfer (LET) 1.8 - 13 MeV•cm2•mg-1 to cover the most critical range of the Weibull curve for those devices. As during the previous experiment, we observed and documented non-destructive heavy ion-induced micromirror state changes. All SEUs were always cleared with a soft reset (that is, sending a new pattern to the device). The DMDs we tested did not experience single-event induced permanent damage or functional changes that required a hard reset (power cycle), even at high ion fluences. Based on the data obtained in the experiments we predict micromirror in-orbit upset rate of 5.6 micromirrors in 24 hours in-orbit for the tested devices. This suggests that the heavy-ion induced SEU rate burden for a DMD-based instrument will be manageable when exposed to solar particle fluxes and cosmic rays in orbit.

Formation of S-type planets in close binaries: scattering induced tidal capture of circumbinary planets

NASA Astrophysics Data System (ADS)

Gong, Yan-Xiang; Ji, Jianghui

2018-05-01

Although several S-type and P-type planets in binary systems were discovered in past years, S-type planets have not yet been found in close binaries with an orbital separation not more than 5 au. Recent studies suggest that S-type planets in close binaries may be detected through high-accuracy observations. However, nowadays planet formation theories imply that it is difficult for S-type planets in close binaries systems to form in situ. In this work, we extensively perform numerical simulations to explore scenarios of planet-planet scattering among circumbinary planets and subsequent tidal capture in various binary configurations, to examine whether the mechanism can play a part in producing such kind of planets. Our results show that this mechanism is robust. The maximum capture probability is ˜10%, which can be comparable to the tidal capture probability of hot Jupiters in single star systems. The capture probability is related to binary configurations, where a smaller eccentricity or a low mass ratio of the binary will lead to a larger probability of capture, and vice versa. Furthermore, we find that S-type planets with retrograde orbits can be naturally produced via capture process. These planets on retrograde orbits can help us distinguish in situ formation and post-capture origin for S-type planet in close binaries systems. The forthcoming missions (PLATO) will provide the opportunity and feasibility to detect such planets. Our work provides several suggestions for selecting target binaries in search for S-type planets in the near future.

Very Low-mass Stellar and Substellar Companions to Solar-like Stars from MARVELS. VI. A Giant Planet and a Brown Dwarf Candidate in a Close Binary System HD 87646

NASA Astrophysics Data System (ADS)

Ma, Bo; Ge, Jian; Wolszczan, Alex; Muterspaugh, Matthew W.; Lee, Brian; Henry, Gregory W.; Schneider, Donald P.; Martín, Eduardo L.; Niedzielski, Andrzej; Xie, Jiwei; Fleming, Scott W.; Thomas, Neil; Williamson, Michael; Zhu, Zhaohuan; Agol, Eric; Bizyaev, Dmitry; Nicolaci da Costa, Luiz; Jiang, Peng; Martinez Fiorenzano, A. F.; González Hernández, Jonay I.; Guo, Pengcheng; Grieves, Nolan; Li, Rui; Liu, Jane; Mahadevan, Suvrath; Mazeh, Tsevi; Nguyen, Duy Cuong; Paegert, Martin; Sithajan, Sirinrat; Stassun, Keivan; Thirupathi, Sivarani; van Eyken, Julian C.; Wan, Xiaoke; Wang, Ji; Wisniewski, John P.; Zhao, Bo; Zucker, Shay

2016-11-01

We report the detections of a giant planet (MARVELS-7b) and a brown dwarf (BD) candidate (MARVELS-7c) around the primary star in the close binary system, HD 87646. To the best of our knowledge, it is the first close binary system with more than one substellar circumprimary companion that has been discovered. The detection of this giant planet was accomplished using the first multi-object Doppler instrument (KeckET) at the Sloan Digital Sky Survey (SDSS) telescope. Subsequent radial velocity observations using the Exoplanet Tracker at the Kitt Peak National Observatory, the High Resolution Spectrograph at the Hobby Eberley telescope, the “Classic” spectrograph at the Automatic Spectroscopic Telescope at the Fairborn Observatory, and MARVELS from SDSS-III confirmed this giant planet discovery and revealed the existence of a long-period BD in this binary. HD 87646 is a close binary with a separation of ˜22 au between the two stars, estimated using the Hipparcos catalog and our newly acquired AO image from PALAO on the 200 inch Hale Telescope at Palomar. The primary star in the binary, HD 87646A, has {T}{eff} = 5770 ± 80 K, log g = 4.1 ± 0.1, and [Fe/H] = -0.17 ± 0.08. The derived minimum masses of the two substellar companions of HD 87646A are 12.4 ± 0.7 {M}{Jup} and 57.0 ± 3.7 {M}{Jup}. The periods are 13.481 ± 0.001 days and 674 ± 4 days and the measured eccentricities are 0.05 ± 0.02 and 0.50 ± 0.02 respectively. Our dynamical simulations show that the system is stable if the binary orbit has a large semimajor axis and a low eccentricity, which can be verified with future astrometry observations.

Satellite services system analysis study. Volume 1: Executive summary

NASA Technical Reports Server (NTRS)

1981-01-01

Service requirements are considered. Topics include development of on-orbit operations scenarios, service equipment summary, crew interaction, and satellite features facilitating servicing. Service equipment concepts are considered. Topics include payload deployment, close proximity retrieval, on-orbit servicing, backup/contingency, delivery/retrieval of high energy payloads, Earth return, optional service, and advanced capabilities. Program requirements are assessed.

Closeup view of the mid deck aft wall of the ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Close-up view of the mid deck aft wall of the Orbiter Discovery showing a mission specific configuration of stowage lockers within the modular system designed for maximum flexibility. This photograph was taken at Kennedy Space Center. - Space Transportation System, Orbiter Discovery (OV-103), Lyndon B. Johnson Space Center, 2101 NASA Parkway, Houston, Harris County, TX

Review of investigations performed in the USSR on close approaches of comets to Jupiter and the evolution of cometary orbits

NASA Technical Reports Server (NTRS)

Kazimirchak-Polonskaya, E. I.

1976-01-01

Methods are reviewed for calculating the evolution of cometary orbits with emphasis on the orbital changes that take place when comets pass within the spheres of action of giant planets. Topics discussed include: differences and difficulties in methods used for the calculation of large perturbations by Jupiter; the construction of numerical theories of motion covering the whole period of observations of each comet, allowing for planetary perturbations and the effects of nongravitational forces; and investigations of the evolution of cometary orbits over the 400 year interval 1660-2060. The classical theory of cometary capture is briefly discussed.

Early Mission Maneuver Operations for the Deep Space Climate Observatory

NASA Technical Reports Server (NTRS)

Roberts, Craig; Case, Sara; Reagoso, John

2015-01-01

DSCOVR Lissajous Orbit sized such that orbit track never extends beyond 15 degrees from Earth-Sun line (as seen from Earth). Requiring delta-V maneuvers, control orbit to obey a Solar Exclusion Zone (SEZ) cone of half-angle 4 degrees about the Earth-Sun line. Spacecraft should never be less than 4 degrees from solar center as seen from Earth. Following Lissajous Orbit Insertion (LOI), DSCOVR should be in an opening phase that just skirts the 4-degree SEZ. Maximizes time to the point where a closing Lissajous will require avoidance maneuvers to keep it out of the SEZ. Station keeping maneuvers should take no more than 15 minutes

Digital Cellular Solid Pressure Vessels: A Novel Approach for Human Habitation in Space

NASA Technical Reports Server (NTRS)

Cellucci, Daniel; Jenett, Benjamin; Cheung, Kenneth C.

2017-01-01

It is widely assumed that human exploration beyond Earth's orbit will require vehicles capable of providing long duration habitats that simulate an Earth-like environment - consistent artificial gravity, breathable atmosphere, and sufficient living space- while requiring the minimum possible launch mass. This paper examines how the qualities of digital cellular solids - high-performance, repairability, reconfigurability, tunable mechanical response - allow the accomplishment of long-duration habitat objectives at a fraction of the mass required for traditional structural technologies. To illustrate the impact digital cellular solids could make as a replacement to conventional habitat subsystems, we compare recent proposed deep space habitat structural systems with a digital cellular solids pressure vessel design that consists of a carbon fiber reinforced polymer (CFRP) digital cellular solid cylindrical framework that is lined with an ultra-high molecular weight polyethylene (UHMWPE) skin. We use the analytical treatment of a linear specific modulus scaling cellular solid to find the minimum mass pressure vessel for a structure and find that, for equivalent habitable volume and appropriate safety factors, the use of digital cellular solids provides clear methods for producing structures that are not only repairable and reconfigurable, but also higher performance than their conventionally manufactured counterparts.

Geocam Space: Enhancing Handheld Digital Camera Imagery from the International Space Station for Research and Applications

NASA Technical Reports Server (NTRS)

Stefanov, William L.; Lee, Yeon Jin; Dille, Michael

2016-01-01

Handheld astronaut photography of the Earth has been collected from the International Space Station (ISS) since 2000, making it the most temporally extensive remotely sensed dataset from this unique Low Earth orbital platform. Exclusive use of digital handheld cameras to perform Earth observations from the ISS began in 2004. Nadir viewing imagery is constrained by the inclined equatorial orbit of the ISS to between 51.6 degrees North and South latitude, however numerous oblique images of land surfaces above these latitudes are included in the dataset. While unmodified commercial off-the-shelf digital cameras provide only visible wavelength, three-band spectral information of limited quality current cameras used with long (400+ mm) lenses can obtain high quality spatial information approaching 2 meters/ground pixel resolution. The dataset is freely available online at the Gateway to Astronaut Photography of Earth site (http://eol.jsc.nasa.gov), and now comprises over 2 million images. Despite this extensive image catalog, use of the data for scientific research, disaster response, commercial applications and visualizations is minimal in comparison to other data collected from free-flying satellite platforms such as Landsat, Worldview, etc. This is due primarily to the lack of fully-georeferenced data products - while current digital cameras typically have integrated GPS, this does not function in the Low Earth Orbit environment. The Earth Science and Remote Sensing (ESRS) Unit at NASA Johnson Space Center provides training in Earth Science topics to ISS crews, performs daily operations and Earth observation target delivery to crews through the Crew Earth Observations (CEO) Facility on board ISS, and also catalogs digital handheld imagery acquired from orbit by manually adding descriptive metadata and determining an image geographic centerpoint using visual feature matching with other georeferenced data, e.g. Landsat, Google Earth, etc. The lack of full geolocation information native to the data makes it difficult to integrate astronaut photographs with other georeferenced data to facilitate quantitative analysis such as urban land cover/land use classification, change detection, or geologic mapping. The manual determination of image centerpoints is both time and labor-intensive, leading to delays in releasing geolocated and cataloged data to the public, such as the timely use of data for disaster response. The GeoCam Space project was funded by the ISS Program in 2015 to develop an on-orbit hardware and ground-based software system for increasing the efficiency of geolocating astronaut photographs from the ISS (Fig. 1). The Intelligent Robotics Group at NASA Ames Research Center leads the development of both the ground and on-orbit systems in collaboration with the ESRS Unit. The hardware component consists of modified smartphone elements including cameras, central processing unit, wireless Ethernet, and an inertial measurement unit (gyroscopes/accelerometers/magnetometers) reconfigured into a compact unit that attaches to the base of the current Nikon D4 camera - and its replacement, the Nikon D5 - and connects using the standard Nikon peripheral connector or USB port. This provides secondary, side and downward facing cameras perpendicular to the primary camera pointing direction. The secondary cameras observe calibration targets with known internal X, Y, and Z position affixed to the interior of the ISS to determine the camera pose corresponding to each image frame. This information is recorded by the GeoCam Space unit and indexed for correlation to the camera time recorded for each image frame. Data - image, EXIF header, and camera pose information - is transmitted to the ground software system (GeoRef) using the established Ku-band USOS downlink system. Following integration on the ground, the camera pose information provides an initial geolocation estimate for the individual film frame. This new capability represents a significant advance in geolocation from the manual feature-matching approach for both nadir and off-nadir viewing imagery. With the initial geolocation estimate, full georeferencing of an image is completed using the rapid tie-pointing interface in GeoRef, and the resulting data is added to the Gateway to Astronaut Photography of Earth online database in both Geotiff and Keyhole Markup Language (kml) formats. The integration of the GeoRef software component of Geocam Space into the CEO image cataloging workflow is complete, and disaster response imagery acquired by the ISS crew is now fully georeferenced as a standard data product. The on-orbit hardware component (GeoSens) is in final prototyping phase, and is on-schedule for launch to the ISS in late 2016. Installation and routine use of the Geocam Space system for handheld digital camera photography from the ISS is expected to significantly improve the usefulness of this unique dataset for a variety of public- and private-sector applications.

Precise multi-instrument data on exceptional fireballs recorded over Central Europe in the period 2012-2014

NASA Astrophysics Data System (ADS)

Spurny, P.; Borovicka, J.

2014-07-01

Introduction: Instrumental recordings of fireballs provide an excellent means of examining the physical and structural properties of larger meteoroids, as well as their temporal and spatial distribution in the Solar System. Except direct information about this component of interplanetary bodies this study also yields very valuable knowledge about their parent bodies, asteroids and comets. In some special and very rare cases, when such instrumentally observed fireball terminates by a meteorite fall, we have even direct information about the composition, structure and mineralogy not only of this particular meteorite but also of its parent body. The most efficient systems for systematic fireball observations are so-called fireball networks. In this work we present precise and complex data on several exceptional fireballs based on photographic and photoelectric records taken by the Czech Fireball Network, which is the longest continuously operated and the most developed part of the European Fireball Network (EN). Instruments and data processing: The Czech part of the EN has been entirely modernized in the last decade and its operation was in the large extent automatized [1]. This change significantly increased not only efficiency but also quality and complexity of our observations. However, this observing system, which provides us with photographic and photoelectric data about fireballs brighter than -4 magnitude, still uses photographic films, which brings some limitations for the data processing. Primarily it implies a non-negligible delay between data acquisition and their analysis as we had to transport photographic films physically from remote stations and only then to develop and digitize them. There is also much lower efficiency of observations during the full Moon period than during moonless nights. Taking the advantage of fast progress of digital photography, we have constructed a new generation of the Digital Autonomous Fireball Observatory (DAFO), which provides us with high-resolution digital images available immediately after their recording. This observatory, developed during the last 2 years, sorted out all the above-mentioned disadvantages. These sophisticated digital cameras are currently being deployed on the stations of the Czech Fireball Network. In this work, we present the first data from this new observing system and the comparison with the previous one. Along with this significant modernization we also improved our software for positional and photometric measurement of photographic records, which partly automatizes this time consuming work and make it much more efficient, easier, and even more precise. This observing system based on the DAFO's, provides us not only with the similarly precise dataset of fireballs as the previous large format film system but thanks to the different observing strategy and higher sensitivity limit, significantly increased effective observing time and number of recorded fireballs. Average absolute positional accuracy for the recorded fireballs stayed similar for both systems and it is about 15 m for each point on a fireball luminous trajectory. Results: To demonstrate this fact, we present complete and precise data on atmospheric trajectories, orbits, lightcurves and dynamics for several fireballs, which are in some sense exceptional and which were recorded by both systems in the last two years. This sample contains, among others the cases which very probably terminate by the fall of a small meteorite, the cases with interesting internal structure and orbital characteristics and also the cases with interesting orbits with respect to their structural properties (i.e. cometary material on a typical asteroidal orbit and vice versa). As the examples of uniqueness of our data we can mention recording of the deep penetrating Geminid fireball (EN141212) which certainly terminated by the fall of a small, only tens of grams meteorite. This unique case with very precise trajectory, dynamic and orbital data (one of the most precise Geminid ever observed) proved that in some special cases even meteoroids with a high initial velocity of 36 km/s can produce a meteorite and that there is real possibility that we could find a piece of Phaethon, the parent of Geminids. Another example is the fireball designated EN130114 which was recorded only by our new digital cameras (it was during the full Moon period). The main exceptionality of this case consists in its lowest ever observed initial velocity which we recorded for natural interplanetary body. Its initial speed of only 11.090 km/s means among others that this meteoroid orbited Sun on a very Earth-like orbit. All presented fireballs well document the high standard of our observations and their usefulness for better knowledge of properties of meteoroids and their parents as well as their distribution in the Solar System.

[Understanding chair-side digital technology for stomatology from an engineering viewpoint].

PubMed

Zhao, Y J; Wang, Y

2018-04-09

In recent years with the rapid development of digital technology for stomatology, the application field, application model, technical features and technical connotation of the chair-side digital technology has got development and change. The open modular system has gradually replaced the traditional closed system, and the application field of digital technology is no longer limited to chair-side dental restoration, it also has been extend to various kinds of chair-side digital treatment-assisted technology. In this paper, from the engineering point of view, the up to date general connotation of chair-side digital technology was explained, the characteristics and the development of each unit in chair-side digital technology were analyzed, and the application pattern and the localization status were also discussed in this paper. The aim of this paper was to introduce the trend of chair-side digital technological to readers and to better guide clinical application.

The Orbital Design of Alpha Centauri Exoplanet Satellite (ACESat)

NASA Technical Reports Server (NTRS)

Weston, Sasha; Belikov, Rus; Bendek, Eduardo

2015-01-01

Exoplanet candidates discovered by Kepler are too distant for biomarkers to be detected with foreseeable technology. Alpha Centauri has high separation from other stars and is of close proximity to Earth, which makes the binary star system 'low hanging fruit' for scientists. Alpha Centauri Exoplanet Satellite (ACESat) is a mission proposed to Small Explorer Program (SMEX) that will use a coronagraph to search for an orbiting planet around one of the stars of Alpha Centauri. The trajectory design for this mission is presented here where three different trajectories are considered: Low Earth Orbit (LEO), Geosynchronous Orbit (GEO) and a Heliocentric Orbit. Uninterrupted stare time to Alpha Centauri is desirable for meeting science requirements, or an orbit that provides 90% stare time to the science target. The instrument thermal stability also has stringent requirements for proper function, influencing trajectory design.

Digital evaluation of orbital development after self-inflating hydrogel expansion in Chinese children with congenital microphthalmia.

PubMed

Hou, Zhijia; Xian, Junfang; Chang, Qinglin; Wei, Wenbin; Li, Dongmei

2016-05-01

Assessment of the growth of bony orbit in children with blind microphthalmia is essential to its management. In this study, variables were measured to evaluate the development of the bony microphthalmic orbits after treatment with self-inflating hydrogel expanders. This is a retrospective study with an interventional case series. Thirteen pediatric patients with congenital unilateral blind microphthalmia who had undergone tissue expansion with hydrogel expanders and computed tomography (CT) scanning before and after operation were included in the study. The orbital volume, depth, width, and height and retardation of the orbital rims before and after treatment were measured and analyzed using the iPlan Cranial Software. The mean age at the time of first implantation was 44 months (range, 3-113 months). Of the 13 patients, eleven received orbital expansion, while two received socket expansion. In the orbital expansion group, the mean microphthalmic/contralateral ratio (MCR) of orbital volume was 79.3% before surgery, which increased to 89.8% 3 years post operation (P < 0.001). The mean MCR of orbital width also increased from 88.8% to 91.8% (P = 0.003). The development of inferior and lateral rims showed the greatest retardation before treatment; the retardation of these two rims decreased significantly at the final measurement (P = 0.004). It is also noted that the development of the microphthalmic orbits was limited in the two patients who only underwent socket expansion. The affected orbit enlarged in children with congenital blind microphthalmia following treatment with hydrogel expanders; this suggested that microphthalmia-associated orbital asymmetry can be treated with self-inflating hydrogel expanders. Copyright © 2016 British Association of Plastic, Reconstructive and Aesthetic Surgeons. Published by Elsevier Ltd. All rights reserved.

The Daytime Craterids, a radar-detected meteor shower outburst from hyperbolic comet C/2007 W1 (Boattini)

NASA Astrophysics Data System (ADS)

Wiegert, P. A.; Brown, P. G.; Weryk, R. J.; Wong, D. K.

2011-06-01

We report a new daytime meteor shower detected with the Canadian Meteor Orbit Radar (CMOR). This shower has a radiant in the southern constellation Crater. The Daytime Craterid shower was observed in 2003 and 2008 but not in any of the other years in the 2002-09 interval. The strength of this shower in the years observed is equivalent to a daily averaged zenithal hourly rate (ZHR) over 30, with a peak ZHR likely much higher at the time of the outburst. The orbital elements of the shower closely match those of Comet C/2007 W1 (Boattini), which passed perihelion in 2007. The orbit of C/2007 W1 is nominally hyperbolic orbit making this the first meteor shower detected from a clearly unbound comet. The 2003 outburst of the Daytime Craterid shower indicates that this comet must have recently been transferred to an unbound orbit from a bound one, likely through a close encounter with a giant planet. As a result we conclude that this shower provides us with one of the few examples of showers originating from the population of nearly isotropic comets. The stream is difficult to model owing to its proximity to the orbits of Jupiter, Saturn and the Earth. However, the intermittent nature of the shower can be largely understood from numerical simulations. No outbursts of similar strength are expected in the next decade, with the possible exception of 2015.

Orbit classification in an equal-mass non-spinning binary black hole pseudo-Newtonian system

NASA Astrophysics Data System (ADS)

Zotos, Euaggelos E.; Dubeibe, F. L.; González, Guillermo A.

2018-04-01

The dynamics of a test particle in a non-spinning binary black hole system of equal masses is numerically investigated. The binary system is modeled in the context of the pseudo-Newtonian circular restricted three-body problem, such that the primaries are separated by a fixed distance and move in a circular orbit around each other. In particular, the Paczyński-Wiita potential is used for describing the gravitational field of the two non-Newtonian primaries. The orbital properties of the test particle are determined through the classification of the initial conditions of the orbits, using several values of the Jacobi constant, in the Hill's regions of possible motion. The initial conditions are classified into three main categories: (i) bounded, (ii) escaping and (iii) displaying close encounters. Using the smaller alignment index (SALI) chaos indicator, we further classify bounded orbits into regular, sticky or chaotic. To gain a complete view of the dynamics of the system, we define grids of initial conditions on different types of two-dimensional planes. The orbital structure of the configuration plane, along with the corresponding distributions of the escape and collision/close encounter times, allow us to observe the transition from the classical Newtonian to the pseudo-Newtonian regime. Our numerical results reveal a strong dependence of the properties of the considered basins with the Jacobi constant as well as with the Schwarzschild radius of the black holes.

The Influence of the Orbital Evolution of Main Belt Asteroids on Their Spin Vectors

NASA Astrophysics Data System (ADS)

Skoglöv, E.; Erikson, A.

2002-11-01

It was found that certain features in the observed spin vector distribution of main belt asteroids can be explained by the differences in the dynamical spin vector evolution between objects with high and low orbital inclinations. In particular, the deficiency of high-inclination objects whose spin vectors are close to the ecliptic plane can be accounted for. The present spin vector distribution of main belt asteroids is due to several factors connected with their collisional and dynamical evolution. In this paper, the influence of the orbital evolution on the spin axis of asteroids is examined in the case of 25 objects with typical main belt orbital evolution and 125 synthetic objects, during an integration over a time period of 1 Myr. This investigation produced the following general results: • The difference between maximum and minimum obliquity increases in an approximately linear fashion with increasing orbital inclination of the studied objects. • The inclination is the major factor influencing the magnitude of the obliquity variation. This variation is generally larger for asteroids with their initial spin vectors located close to the orbital plane. • In general, the regular obliquity differences are relatively insensitive to differences in the shape, composition, and spin rate of the asteroids. The result is compared with the properties of the observed spin vectors for 73 main belt asteroids and good agreement is found between the above results and the existing spin vector distribution.

Comprehensive analysis of airborne contaminants from recent Spacelab missions

NASA Technical Reports Server (NTRS)

Matney, M. L.; Boyd, J. F.; Covington, P. A.; Leano, H. J.; Pierson, D. L.; Limero, T. F.; James, J. T.

1993-01-01

The Shuttle experiences unique air contamination problems because of microgravity and the closed environment. Contaminant build-up in the closed atmosphere and the lack of a gravitational settling mechanism have produced some concern in previous missions about the amount of solid and volatile airborne contaminants in the Orbiter and Spacelab. Degradation of air quality in the Orbiter/Spacelab environment, through processes such as chemical contamination, high solid-particulate levels, and high microbial levels, may affect crew performance and health. A comprehensive assessment of the Shuttle air quality was undertaken during STS-40 and STS-42 missions, in which a variety of air sampling and monitoring techniques were employed to determine the contaminant load by characterizing and quantitating airborne contaminants. Data were collected on the airborne concentrations of volatile organic compounds, microorganisms, and particulate matter collected on Orbiter/Spacelab air filters. The results showed that STS-40/42 Orbiter/Spacelab air was toxicologically safe to breathe, except during STS-40 when the Orbiter Refrigerator/Freezer unit was releasing noxious gases in the middeck. On STS-40, the levels of airborne bacteria appeared to increase as the mission progressed; however, this trend was not observed for the STS-42 mission. Particulate matter in the Orbiter/Spacelab air filters was chemically analyzed in order to determine the source of particles. Only small amounts of rat hair and food bar (STS-40) and traces of soiless medium (STS-42) were detected in the Spacelab air filters, indicating that containment for Spacelab experiments was effective.

Identification of New Orbits to Enable Future Missions for the Exploration of the Martian Moon Phobos

NASA Astrophysics Data System (ADS)

Zamaro, Mattia; Biggs, James D.

One of the paramount stepping stones towards NASA's long-term goal of undertaking human missions to Mars is the exploration of the Martian moons. In this paper, a showcase of various classes of non-Keplerian orbits are identified and a number of potential mission applications in the Mars-Phobos system are proposed. These applications include: low-thrust hovering around Phobos for close-range observations; Libration Point Orbits in enhanced three-body dynamics to enable unique low-cost operations for space missions in the proximity of Phobos; their manifold structure for high-performance landing/take-off maneuvers to and from Phobos' surface; Quasi-Satellite Orbits for long-period station-keeping and maintenance. In particular, these orbits could exploit Phobos' occulting bulk as a passive radiation shield during future manned flights to Mars to reduce human exposure to radiation. Moreover, the latter orbits can be used as an orbital garage, requiring no orbital maintenance, where a spacecraft could make planned pit-stops during a round-trip mission to Mars.

Analytical method for the effects of the asteroid belt on planetary orbits

NASA Technical Reports Server (NTRS)

Mayo, A. P.

1979-01-01

Analytic expressions are derived for the perturbation of planetary orbits due to a thick constant-density asteroid belt. The derivations include extensions and adaptations of Plakhov's (1968) analytic expressions for the perturbations in five of the orbital elements for closed orbits around Saturn's rings. The equations of Plakhov are modified to include the effect of ring thickness, and additional equations are derived for the perturbations in the sixth orbital element, the mean anomaly. The gravitational potential and orbital perturbations are derived for the asteroid belt with and without thickness, and for a hoop approximation to the belt. The procedures are also applicable to Saturn's rings and the newly discovered rings of Uranus. The effects of the asteroid belt thickness on the gravitational potential coefficients and the orbital motions are demonstrated. Comparisons between the Mars orbital perturbations obtained by using the analytic expressions and those obtained by numerical integration are discussed. The effects of the asteroid belt on earth-based ranging to Mars are also demonstrated.

Simple control laws for low-thrust orbit transfers

NASA Technical Reports Server (NTRS)

Petropoulos, Anastassios E.

2003-01-01

Two methods are presented by which to determine both a thrust direction and when to apply thrust to effect specified changes in any of the orbit elements except for true anomaly, which is assumed free. The central body is assumed to be a point mass, and the initial and final orbits are assumed closed. Thrust, when on, is of a constant value, and specific impulse is constant. The thrust profiles derived from the two methods are not propellant-optimal, but are based firstly on the optimal thrust directions and location on the osculating orbit for changing each of the orbit elements and secondly on the desired changes in the orbit elements. Two examples of transfers are presented, one in semimajor axis and inclination, and one in semimajor axis and eccentricity. The latter compares favourably with a propellant-optimized transfer between the same orbits. The control laws have few input parameters, but can still capture the complexity of a wide variety of orbit transfers.

Interference elimination in digital controllers of automation systems of oil and gas complex

NASA Astrophysics Data System (ADS)

Solomentsev, K. Yu; Fugarov, D. D.; Purchina, O. A.; Poluyan, A. Y.; Nesterchuk, V. V.; Petrenkova, S. B.

2018-05-01

The given article considers the problems arising in the process of digital governors development for the systems of automatic control. In the case of interference, and also in case of high frequency of digitization, digital differentiation gives a big error. The problem is that the derivative is calculated as the difference of two close variables. The method of differentiation is offered to reduce this error, when there is a case of averaging the difference quotient of the series of meanings. The structure chart for the implementation of this differentiation method is offered in the case of governors construction.

Spirit's Course

NASA Technical Reports Server (NTRS)

2004-01-01

[figure removed for brevity, see original site] [figure removed for brevity, see original site] Figure 1Figure 2

This digital elevation map shows the topography of the 'Columbia Hills,' just in front of the Mars Exploration Rover Spirit's current position. Rover planners have plotted the safest route for Spirit to climb to the front hill, called 'West Spur.' The black line in the middle of the image represents the rover's traverse path, which starts at 'Hank's Hollow' and ends at the top of 'West Spur.' Scientists are sending Spirit up the hill to investigate the interesting rock outcrops visible in images taken by the rover. Data from the Mars Orbital Camera on the orbiting Mars Global Surveyor were used to create this 3-D map.

In figure 1, the digital map shows the slopes of the 'Columbia Hills,' just in front of the Mars Exploration Rover Spirit's current position. Colors indicate the slopes of the hills, with red areas being the gentlest and blue the steepest. Rover planners have plotted the safest route for Spirit to climb the front hill, called 'West Spur.' The path is indicated here with a curved black line. Stereo images from the Mars Orbital Camera on the orbiting Mars Global Surveyor were used to create this 3-D map.

In figure 2, the map shows the north-facing slopes of the 'Columbia Hills,' just in front of the Mars Exploration Rover Spirit's current position. Bright areas indicate surfaces sloping more toward the north than dark areas. To reach the rock outcrop at the top of the hill, engineers will aim to drive the rover around the dark areas, which would yield less solar power. The curved black line in the middle represents the rover's planned traverse path.

Developed lower-positioned transverse ligament restricts eyelid opening and folding and determines Japanese as being with or without visible superior palpebral crease.

PubMed

Ban, Midori; Matsuo, Kiyoshi; Ban, Ryokuya; Yuzuriha, Shunsuke; Kaneko, Ai

2013-01-01

We have reported that a developed lower-positioned transverse ligament between the superior-medial orbital rim and the lateral orbital rim on the lateral horn in the lower orbital fat space antagonizes eyelid opening and folding in certain Japanese to produce narrow eye, no visible superior palpebral crease, and full eyelid. In this study, we confirmed relationship between development of the lower-positioned transverse ligament and presence of the superior palpebral crease. We evaluated whether (1) digital immobilization of eyebrow movement during eyelid opening and (2) a developed lower-positioned transverse ligament could classify Japanese subjects as being with or without visible superior palpebral crease. Digital immobilization of eyebrow movement restricted eyelid opening in all subjects without visible superior palpebral crease but did not restrict in any subject with visible superior palpebral crease. Macroscopic and microscopic evidence revealed that the lower-positioned transverse ligament behind the lower orbital septum in subjects without visible superior palpebral crease was significantly more developed than that in subjects with visible superior palpebral crease. Since a developed lower-positioned transverse ligament antagonizes opening and folding of the anterior lamella of the upper eyelid in subjects without visible superior palpebral crease, these individuals open their eyelids by lifting the eyebrow with the anterior lamella and the lower-positioned transverse ligament owing to increased tonic contraction of the frontalis muscle, in addition to the retractile force of the levator aponeurotic expansions. In subjects with visible superior palpebral crease, the undeveloped lower-positioned transverse ligament does not antagonize opening and folding of the anterior lamella, and so they open their eyelids by folding the anterior lamella on the superior palpebral crease via the retractile force of the levator aponeurotic expansions.

Developed Lower-Positioned Transverse Ligament Restricts Eyelid Opening and Folding and Determines Japanese as Being With or Without Visible Superior Palpebral Crease

PubMed Central

Ban, Midori; Matsuo, Kiyoshi; Ban, Ryokuya; Yuzuriha, Shunsuke; Kaneko, Ai

2013-01-01

Introduction: We have reported that a developed lower-positioned transverse ligament between the superior-medial orbital rim and the lateral orbital rim on the lateral horn in the lower orbital fat space antagonizes eyelid opening and folding in certain Japanese to produce narrow eye, no visible superior palpebral crease, and full eyelid. In this study, we confirmed relationship between development of the lower-positioned transverse ligament and presence of the superior palpebral crease. Methods: We evaluated whether (1) digital immobilization of eyebrow movement during eyelid opening and (2) a developed lower-positioned transverse ligament could classify Japanese subjects as being with or without visible superior palpebral crease. Results: Digital immobilization of eyebrow movement restricted eyelid opening in all subjects without visible superior palpebral crease but did not restrict in any subject with visible superior palpebral crease. Macroscopic and microscopic evidence revealed that the lower-positioned transverse ligament behind the lower orbital septum in subjects without visible superior palpebral crease was significantly more developed than that in subjects with visible superior palpebral crease. Conclusions: Since a developed lower-positioned transverse ligament antagonizes opening and folding of the anterior lamella of the upper eyelid in subjects without visible superior palpebral crease, these individuals open their eyelids by lifting the eyebrow with the anterior lamella and the lower-positioned transverse ligament owing to increased tonic contraction of the frontalis muscle, in addition to the retractile force of the levator aponeurotic expansions. In subjects with visible superior palpebral crease, the undeveloped lower-positioned transverse ligament does not antagonize opening and folding of the anterior lamella, and so they open their eyelids by folding the anterior lamella on the superior palpebral crease via the retractile force of the levator aponeurotic expansions. PMID:23943676

Co-registration of Laser Altimeter Tracks with Digital Terrain Models and Applications in Planetary Science

NASA Technical Reports Server (NTRS)

Glaeser, P.; Haase, I.; Oberst, J.; Neumann, G. A.

2013-01-01

We have derived algorithms and techniques to precisely co-register laser altimeter profiles with gridded Digital Terrain Models (DTMs), typically derived from stereo images. The algorithm consists of an initial grid search followed by a least-squares matching and yields the translation parameters at sub-pixel level needed to align the DTM and the laser profiles in 3D space. This software tool was primarily developed and tested for co-registration of laser profiles from the Lunar Orbiter Laser Altimeter (LOLA) with DTMs derived from the Lunar Reconnaissance Orbiter (LRO) Narrow Angle Camera (NAC) stereo images. Data sets can be co-registered with positional accuracy between 0.13 m and several meters depending on the pixel resolution and amount of laser shots, where rough surfaces typically result in more accurate co-registrations. Residual heights of the data sets are as small as 0.18 m. The software can be used to identify instrument misalignment, orbit errors, pointing jitter, or problems associated with reference frames being used. Also, assessments of DTM effective resolutions can be obtained. From the correct position between the two data sets, comparisons of surface morphology and roughness can be made at laser footprint- or DTM pixel-level. The precise co-registration allows us to carry out joint analysis of the data sets and ultimately to derive merged high-quality data products. Examples of matching other planetary data sets, like LOLA with LRO Wide Angle Camera (WAC) DTMs or Mars Orbiter Laser Altimeter (MOLA) with stereo models from the High Resolution Stereo Camera (HRSC) as well as Mercury Laser Altimeter (MLA) with Mercury Dual Imaging System (MDIS) are shown to demonstrate the broad science applications of the software tool.

A Topographic Image Map of The Mc-18 Quadrangle "coprates" At 1: 2,000,000 Using Data Obtained From The Mars Orbiter Camera and The Mars Orbiter Laser Altimeter of Mars Global Surveyor

NASA Astrophysics Data System (ADS)

Niedermaier, G.; Wählisch, M.; van Gasselt, S.; Scholten, F.; Wewel, F.; Roatsch, T.; Matz, K.-D.; Jaumann, R.

We present a new topographic image map of Mars using 8 bit data obtained from the Mars Orbiter Camera (MOC) of the Mars Global Surveyor (MGS) [1]. The new map covers the Mars surface from 270 E (90 W) to 315 E (45 W) and from 0 North to 30 South with a resolution of 231.529 m/pixel (256 pixel/degree). For map creation, digital image processing methods have been applied. Furthermore, we managed to de- velop a general processing method for creating image mosaics based on MOC data. From a total amount of 66,081 images, 4,835 images (4,339 Context and 496 Geodesy images [3]) were finally used for the creation of the mosaic. After radiometric and brightness corrections, the images were Mars referenced [5], geometrically [6] cor- rected and sinusoidal map projected [4] using a global Martian Digital Terrain Model (DTM), developed by the DLR and based on MGS Mars Orbiter Laser Altimeter (MOLA) topographic datasets [2]. Three layers of MOC mosaics were created, which were stacked afterwards. The upper layer contains the context images with a resolution < 250 m/pixel. The middle layer contains the images of the Geodesy Campaign with a resolution < 250 m/pixel. The bottom layer consists of the Geodesy Campaign im- ages with a resolution > 250 m/pixel and < 435 m/pixel. The contour lines have been extracted from the global Martian DTM, developed at DLR. The contour data were imported as vector data into Macromedia Freehand as separate layer and corrected interactively. The map format of 1,15 m × 1,39 m represents the western part of the MDIM2 j quadrangle. The map is used for geological and morphological interpreta- tions in order to review and improve our current Viking-based knowledge about the Martian surface. References: [1] www.msss.com [2] wufs.wustl.edu [3] Caplinger, M. and M. Malin, The Mars Orbiter Camera Geodesy Campaign, JGR, in press. [4] Scholten, F., Vol XXXI, Part B2, Wien, 1996, p.351-356 [5] naif.jpl.nasa.gov [6] Kirk, R.L. et al., Geometric Calibration of the Mars Orbiter Cameras and Coalignment with Mars Orbiter Laser Altimeter, (abstract #1863), LPSC XXXII, 2001

N-Body Simulations of Planetary Accretion Around M Dwarf Stars

NASA Astrophysics Data System (ADS)

Ogihara, Masahiro; Ida, Shigeru

2009-07-01

We have investigated planetary accretion from planetesimals in terrestrial planet regions inside the ice line around M dwarf stars through N-body simulations including tidal interactions with disk gas. Because of low luminosity of M dwarfs, habitable zones (HZs) are located in inner regions (~0.1 AU). In the close-in HZ, type-I migration and the orbital decay induced by eccentricity damping are efficient according to the high disk gas density in the small orbital radii. Since the orbital decay is terminated around the disk inner edge and the disk edge is close to the HZ, the protoplanets accumulated near the disk edge affect formation of planets in the HZ. Ice lines are also in relatively inner regions at ~0.3 AU. Due to the small orbital radii, icy protoplanets accrete rapidly and undergo type-I migration before disk depletion. The rapid orbital decay, the proximity of the disk inner edge, and large amount of inflow of icy protoplanets are characteristic in planetary accretion in terrestrial planet regions around M dwarfs. In the case of full efficiency of type-I migration predicted by the linear theory, we found that protoplanets that migrate to the vicinity of the host star undergo close scatterings and collisions, and four to six planets eventually remain in mutual mean-motion resonances and their orbits have small eccentricities (lsim0.01) and they are stable both before and after disk gas decays. In the case of slow migration, the resonant capture is so efficient that densely packed ~40 small protoplanets remain in mutual mean-motion resonances. In this case, they start orbit crossing, after the disk gas decays and eccentricity damping due to tidal interaction with gas is no more effective. Through merging of the protoplanets, several planets in widely separated non-resonant orbits with relatively large eccentricities (~0.05) are formed. Thus, the final orbital configurations (separations, resonant or non-resonant, eccentricity, and distribution) of the terrestrial planets around M dwarfs sensitively depend on strength of type-I migration. We also found that large amount of water-ice is delivered by type-I migration from outer regions and final planets near the inner disk edge around M dwarfs are generally abundant in water-ice except for the innermost one that is shielded by the outer planets, unless type-I migration speed is reduced by a factor of more than 100 from that predicted by the linear theory.

Education, Digitization and Literacy Training: A Historical and Cross-Cultural Perspective

ERIC Educational Resources Information Center

Vlieghe, Joris

2016-01-01

In this article, I deal with the transition from traditional "school" forms of instruction to educational processes that are fully mediated by digital technologies. Against the background of the idea the very institution "school" is closely linked to the invention of the alphabetic writing system and to the need of initiating…

Closing the Digital Gap in Cameroonian Secondary Schools through the CIAC Project

ERIC Educational Resources Information Center

Nganji,, Julius; Kwemain, Roland; Taku, Calisus

2010-01-01

Although with the overwhelming impact of new technologies globally, numerous factors still account for the setbacks in bridging the digital divide in developing nations. Cameroon has for several years been trailing in the employment of Information and Communication Technologies (ICTs) to facilitate learning and teaching in schools. Nevertheless, a…

Semi-automated extraction of longitudinal subglacial bedforms from digital terrain models - Two new methods

NASA Astrophysics Data System (ADS)

Jorge, Marco G.; Brennand, Tracy A.

2017-07-01

Relict drumlin and mega-scale glacial lineation (positive relief, longitudinal subglacial bedforms - LSBs) morphometry has been used as a proxy for paleo ice-sheet dynamics. LSB morphometric inventories have relied on manual mapping, which is slow and subjective and thus potentially difficult to reproduce. Automated methods are faster and reproducible, but previous methods for LSB semi-automated mapping have not been highly successful. Here, two new object-based methods for the semi-automated extraction of LSBs (footprints) from digital terrain models are compared in a test area in the Puget Lowland, Washington, USA. As segmentation procedures to create LSB-candidate objects, the normalized closed contour method relies on the contouring of a normalized local relief model addressing LSBs on slopes, and the landform elements mask method relies on the classification of landform elements derived from the digital terrain model. For identifying which LSB-candidate objects correspond to LSBs, both methods use the same LSB operational definition: a ruleset encapsulating expert knowledge, published morphometric data, and the morphometric range of LSBs in the study area. The normalized closed contour method was separately applied to four different local relief models, two computed in moving windows and two hydrology-based. Overall, the normalized closed contour method outperformed the landform elements mask method. The normalized closed contour method performed on a hydrological relief model from a multiple direction flow routing algorithm performed best. For an assessment of its transferability, the normalized closed contour method was evaluated on a second area, the Chautauqua drumlin field, Pennsylvania and New York, USA where it performed better than in the Puget Lowland. A broad comparison to previous methods suggests that the normalized relief closed contour method may be the most capable method to date, but more development is required.

A Comprehensive Orbit Reconstruction for the Galileo Prime Mission in the J2000 System

NASA Technical Reports Server (NTRS)

Jacobson, Robert A.; Haw, Robert J.; McElrath, Tim P.; Antreasian, Peter G.

1999-01-01

The Galileo spacecraft arrived at Jupiter in December of 1995 to begin an orbital tour of the Jovian system. The objective of the tour was up close study of the planet, its satellites, and its magnetosphere. The spacecraft completed its 11 orbit prime mission in November of 1997 having had 16 successful close encounters with the Galilean satellites (including two prior to Jupiter orbit insertion). Galileo continues to operate and will have made an additional 10 orbits of Jupiter by the date of this Conference. Earlier papers discuss the determination of the spacecraft orbit in support of mission operations from arrival at Jupiter through the first 9 orbits. In this paper we re-examine those earlier orbits and extend the analysis through orbit 12, the first orbit of the Galileo Europa Mission (GEM). The objective of our work is the reconstruction of the spacecraft trajectory together with the development of a consistent set of ephemerides for the Galilean satellites. As a necessary byproduct of the reconstruction we determine improved values for the Jovian system gravitational parameters and for the Jupiter pole orientation angles. Our preliminary analyses have already led to many of the results reported in the scientific literature. Unlike the Galileo Navigation Team which operates in the EME-1950 coordinate system, we elected to work in the (J2000) International Celestial Reference Frame (ICRF), the reference frame of the current JPL planetary and satellite ephemerides as well as the standard frame of the international astronomical and planetary science community. Use of this frame permits more precise modelling of the spacecraft and satellite observations. Moreover, it is the frame of choice for all other operational JPL missions and will probably be the frame for future missions for some time. Consequently, our adoption of the ICRF will facilitate the combination of our results with any obtained from future missions (e.g. the proposed Europa Orbiter mission). In addition, our results may be used by the science community, without need of a reference frame conversion.

Lunar Reconnaissance Orbiter Camera

Science.gov Websites

them out » Traverse featurette Traverse the Apollo Landing Sites & More. By combining LROC imagery , data, and historical data, we've created detailed, interactive maps of the Apollo Landing Sites and taken by the original Apollo crews. ASU maintains the Apollo Digital Image Archive and the March to the

Monitoring forests from space: quantifying forest change by using satellite data.

Treesearch

Jonathan Thompson

2006-01-01

Change is the only constant in forest ecosystems. Quantifying regional-scale forest change is increasingly done with remote sensing, which relies on data sent from digital camera-like sensors mounted to Earth-orbiting satellites. Through remote sensing, changes in forests can be studied comprehensively and uniformly across time and space.

MS Kavandi with camera in Service Module

NASA Image and Video Library

2001-07-16

STS104-E-5125 (16 July 2001) --- Astronaut Janet L. Kavandi, STS-104 mission specialist, uses a camera as she floats through the Zvezda service module aboard the International Space Station (ISS). The five STS-104 crew members were visiting the orbital outpost to perform various tasks. The image was recorded with a digital still camera.

Formation Flying Control Implementation in Highly Elliptical Orbits

NASA Technical Reports Server (NTRS)

Capo-Lugo, Pedro A.; Bainum, Peter M.

2009-01-01

The Tschauner-Hempel equations are widely used to correct the separation distance drifts between a pair of satellites within a constellation in highly elliptical orbits [1]. This set of equations was discretized in the true anomaly angle [1] to be used in a digital steady-state hierarchical controller [2]. This controller [2] performed the drift correction between a pair of satellites within the constellation. The objective of a discretized system is to develop a simple algorithm to be implemented in the computer onboard the satellite. The main advantage of the discrete systems is that the computational time can be reduced by selecting a suitable sampling interval. For this digital system, the amount of data will depend on the sampling interval in the true anomaly angle [3]. The purpose of this paper is to implement the discrete Tschauner-Hempel equations and the steady-state hierarchical controller in the computer onboard the satellite. This set of equations is expressed in the true anomaly angle in which a relation will be formulated between the time and the true anomaly angle domains.

A web system of virtual morphometric globes for Mars and the Moon

NASA Astrophysics Data System (ADS)

Florinsky, I. V.; Garov, A. S.; Karachevtseva, I. P.

2018-09-01

We developed a web system of virtual morphometric globes for Mars and the Moon. As the initial data, we used 15-arc-minutes gridded global digital elevation models (DEMs) extracted from the Mars Orbiter Laser Altimeter (MOLA) and the Lunar Orbiter Laser Altimeter (LOLA) gridded archives. We derived global digital models of sixteen morphometric variables including horizontal, vertical, minimal, and maximal curvatures, as well as catchment area and topographic index. The morphometric models were integrated into the web system developed as a distributed application consisting of a client front-end and a server back-end. The following main functions are implemented in the system: (1) selection of a morphometric variable; (2) two-dimensional visualization of a calculated global morphometric model; (3) 3D visualization of a calculated global morphometric model on the sphere surface; (4) change of a globe scale; and (5) globe rotation by an arbitrary angle. Free, real-time web access to the system is provided. The web system of virtual morphometric globes can be used for geological and geomorphological studies of Mars and the Moon at the global, continental, and regional scales.

Spin orbit torque based electronic neuron

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

Sengupta, Abhronil, E-mail: asengup@purdue.edu; Choday, Sri Harsha; Kim, Yusung

2015-04-06

A device based on current-induced spin-orbit torque (SOT) that functions as an electronic neuron is proposed in this work. The SOT device implements an artificial neuron's thresholding (transfer) function. In the first step of a two-step switching scheme, a charge current places the magnetization of a nano-magnet along the hard-axis, i.e., an unstable point for the magnet. In the second step, the SOT device (neuron) receives a current (from the synapses) which moves the magnetization from the unstable point to one of the two stable states. The polarity of the synaptic current encodes the excitatory and inhibitory nature of themore » neuron input and determines the final orientation of the magnetization. A resistive crossbar array, functioning as synapses, generates a bipolar current that is a weighted sum of the inputs. The simulation of a two layer feed-forward artificial neural network based on the SOT electronic neuron shows that it consumes ∼3× lower power than a 45 nm digital CMOS implementation, while reaching ∼80% accuracy in the classification of 100 images of handwritten digits from the MNIST dataset.« less

The Lunar Mapping and Modeling Portal: Capabilities and Lunar Data Products to support Return to the Moon

NASA Astrophysics Data System (ADS)

Law, E.; Bui, B.; Chang, G.; Goodale, C. E.; Kim, R.; Malhotra, S.; Ramirez, P.; Rodriguez, L.; Sadaqathulla, S.; Nall, M.; Muery, K.

2012-12-01

The Lunar Mapping and Modeling Portal (LMMP), is a multi-center project led by NASA's Marshall Space Flight Center. The LMMP is a web-based Portal and a suite of interactive visualization and analysis tools to enable lunar scientists, engineers, and mission planners to access mapped lunar data products from past and current lunar missions, e.g., Lunar Reconnaissance Orbiter, Apollo, Lunar Orbiter, Lunar Prospector, and Clementine. The Portal allows users to search, view and download a vast number of the most recent lunar digital products including image mosaics, digital elevation models, and in situ lunar resource maps such as iron and hydrogen abundance. The Portal also provides a number of visualization and analysis tools that perform lighting analysis and local hazard assessments, such as, slope, surface roughness and crater/boulder distribution. In this talk, we will give a brief overview of the project. After that, we will highlight various key features and Lunar data products. We will further demonstrate image viewing and layering of lunar map images via our web portal as well as mobile devices.

The effects of heavy ion radiation on digital micromirror device performance

NASA Astrophysics Data System (ADS)

Travinsky, Anton; Vorobiev, Dmitry; Raisanen, Alan D.; Pellish, Jonathan; Ninkov, Zoran; Robberto, Massimo; Heap, Sara

2016-02-01

There is a need for a space-suitable solution to the selection of targets to be observed in astronomical multiobject spectrometers (MOS). A few digital micromirror device (DMD) - based prototype MOS have been developed for use at ground observatories, However their main use will come in deploying a space based mission. The question of DMD performance under in-orbit radiation remains unanswered. DMDs were tested under accelerated heavy-ion radiation (with the control electronics shielded from radiation), with a focus on detection of single-event effects (SEEs) including latch-up events. Testing showed that DMDs are sensitive to non-destructive ion-induced state changes; however, all SEEs were cleared with a soft reset (that is, sending a new pattern to the device). The DMDs did not experience single-event induced permanent damage or functional changes that required a hard reset (power cycle), even at high ion fluences. This suggests that the SSE rate burden will be manageable for a DMD-based instrument when exposed to solar particle fluxes and cosmic rays on orbit.

Data Concentrator

NASA Technical Reports Server (NTRS)

Willett, Mike

2015-01-01

Orbital Research, Inc., developed, built, and tested three high-temperature components for use in the design of a data concentrator module in distributed turbine engine control. The concentrator receives analog and digital signals related to turbine engine control and communicates with a full authority digital engine control (FADEC) or high-level command processor. This data concentrator follows the Distributed Engine Controls Working Group (DECWG) roadmap for turbine engine distributed controls communication development that operates at temperatures at least up to 225 C. In Phase I, Orbital Research developed detailed specifications for each component needed for the system and defined the total system specifications. This entailed a combination of system design, compiling existing component specifications, laboratory testing, and simulation. The results showed the feasibility of the data concentrator. Phase II of this project focused on three key objectives. The first objective was to update the data concentrator design modifications from DECWG and prime contractors. Secondly, the project defined requirements for the three new high-temperature, application-specific integrated circuits (ASICs): one-time programmable (OTP), transient voltage suppression (TVS), and 3.3V. Finally, the project validated each design by testing over temperature and under load.

Development And Test of A Digitally Steered Antenna Array for The Navigator GPS Receiver

NASA Technical Reports Server (NTRS)

Pinto, Heitor David; Valdez, Jennifer E.; Winternitz, Luke M. B.; Hassouneh, Munther A.; Price, Samuel R.

2012-01-01

Global Positioning System (GPS)-based navigation has become common for low-Earth orbit spacecraft as the signal environment is similar to that on the Earth s surface. The situation changes abruptly, however, for spacecraft whose orbital altitudes exceed that of the GPS constellation. Visibility is dramatically reduced and signals that are present may be very weak and more susceptible to interference. GPS receivers effective at these altitudes require increased sensitivity, which often requires a high-gain antenna. Pointing such an antenna can pose a challenge. One efficient approach to mitigate these problems is the use of a digitally steered antenna array. Such an antenna can optimally allocate gain toward desired signal sources and away from interferers. This paper presents preliminary results in the development and test of a digitally steered antenna array for the Navigator GPS research program at NASA s Goddard Space Flight Center. In particular, this paper highlights the development of an array and front-end electronics, the development and test of a real-time software GPS receiver, and implementation of three beamforming methods for combining the signals from the array. Additionally, this paper discusses the development of a GPS signal simulator which produces digital samples of the GPS L1C/A signals as they would be received by an arbitrary antenna array configuration. The simulator models transmitter and receiver dynamics, near-far and multipath interference, and has been a critical component in both the development and test of the GPS receiver. The GPS receiver system was tested with real and simulated GPS signals. Preliminary results show that performance improvement was achieved in both the weak signal and interference environments, matching analytical predictions. This paper summarizes our initial findings and discusses the advantages and limitations of the antenna array and the various beamforming methods.

Singular perturbations and time scales in the design of digital flight control systems

NASA Technical Reports Server (NTRS)

Naidu, Desineni S.; Price, Douglas B.

1988-01-01

The results are presented of application of the methodology of Singular Perturbations and Time Scales (SPATS) to the control of digital flight systems. A block diagonalization method is described to decouple a full order, two time (slow and fast) scale, discrete control system into reduced order slow and fast subsystems. Basic properties and numerical aspects of the method are discussed. A composite, closed-loop, suboptimal control system is constructed as the sum of the slow and fast optimal feedback controls. The application of this technique to an aircraft model shows close agreement between the exact solutions and the decoupled (or composite) solutions. The main advantage of the method is the considerable reduction in the overall computational requirements for the evaluation of optimal guidance and control laws. The significance of the results is that it can be used for real time, onboard simulation. A brief survey is also presented of digital flight systems.

Integrated source and channel encoded digital communication system design study

NASA Technical Reports Server (NTRS)

Alem, W. K.; Huth, G. K.; Simon, M. K.

1978-01-01

The particular Ku-band carrier, PN despreading, and symbol synchronization strategies, which were selected for implementation in the Ku-band transponder aboard the orbiter, were assessed and evaluated from a systems performance viewpoint, verifying that system specifications were met. A study was performed of the design and implementation of tracking techniques which are suitable for incorporation into the Orbiter Ku-band communication system. Emphasis was placed on maximizing tracking accuracy and communication system flexibility while minimizing cost, weight, and system complexity of Orbiter and ground systems hardware. The payload communication study assessed the design and performance of the forward link and return link bent-pipe relay modes for attached and detached payloads. As part of this study, a design for a forward link bent-pipe was proposed which employs a residual carrier but which is tracked by the existing Costas loop.

A study of digital gyro compensation loops. [data conversion routines and breadboard models

NASA Technical Reports Server (NTRS)

1975-01-01

The feasibility is discussed of replacing existing state-of-the-art analog gyro compensation loops with digital computations. This was accomplished by designing appropriate compensation loops for the dry turned TDF gyro, selecting appropriate data conversion and processing techniques and algorithms, and breadboarding the design for laboratory evaluation. A breadboard design was established in which one axis of a Teledyne turned-gimbal TDF gyro was caged digitally while the other was caged using conventional analog electronics. The digital loop was designed analytically to closely resemble the analog loop in performance. The breadboard was subjected to various static and dynamic tests in order to establish the relative stability characteristics and frequency responses of the digital and analog loops. Several variations of the digital loop configuration were evaluated. The results were favorable.

International Ultraviolet Explorer observations of the peculiar variable spectrum of the eclipsing binary R Arae

NASA Technical Reports Server (NTRS)

Mccluskey, G. E.; Kondo, Y.

1983-01-01

The eclipsing binary system R Arae = HD 149730 is a relatively bright southern system with an orbital period of about 4.4 days. It is a single-lined spectroscopic binary. The spectral class of the primary component is B9 Vp. The system was included in a study of mass flow and evolution in close binary systems using the International Ultraviolet Explorer satellite (IUE). Four spectra in the wavelength range from 1150 to 1900 A were obtained with the far-ultraviolet SWP camera, and six spectra in the range from 1900 to 3200 range were obtained with the mid-ultraviolet LWR camera. The close binary R Arae exhibits very unusual ultraviolet spectra. It appears that no other close binary system, observed with any of the orbiting satellites, shows outside-eclipse ultraviolet continuum flux variations of this nature.

Fiber-optic projected-fringe digital interferometry

NASA Technical Reports Server (NTRS)

Mercer, Carolyn R.; Beheim, Glenn

1990-01-01

A phase-stepped projected-fringe interferometer was developed which uses a closed-loop fiber-optic phase-control system to make very accurate surface profile measurements. The closed-loop phase-control system greatly reduces phase-stepping error, which is frequently the dominant source of error in digital interferometers. Two beams emitted from a fiber-optic coupler are combined to form an interference fringe pattern on a diffusely reflecting object. Reflections off of the fibers' output faces are used to create a phase-indicating signal for the closed-loop optical phase controller. The controller steps the phase difference between the two beams by pi/2 radians in order to determine the object's surface profile using a solid-state camera and a computer. The system combines the ease of alignment and automated data reduction of phase-stepping projected-fringe interferometry with the greatly improved phase-stepping accuracy of our closed-loop phase-controller. The system is demonstrated by measuring the profile of a plate containing several convex surfaces whose heights range from 15 to 25 micron high.

New Astrometric Reduction of the USNO Photographic Plates of Planetary Satellites

NASA Astrophysics Data System (ADS)

de Cuyper, J.-P.; Winter, L.; de Decker, G.; Zacharias, N.; Pascu, D.; Arlot, J.-E.; Robert, V.; Lainey, V.

2009-09-01

An international collaboration has been set up between the US Naval Observatory (USNO) in Washington DC, the IMCCE of Paris Observatory (OBSPM) and the Royal Observatory of Belgium (ROB) to make a new astrometric reduction of the USNO archival photographic plates of planetary satellites. In order to obtain a better knowledge of their orbital motions these photographic plates are digitized with the new generation DAMIAN digitizer at the ROB, providing a geometric stability of better than 0.1 μm on the plates. We focus here on a subset of a few hundred photographic plates of the Galilean satellites, taken with the McCormick and the USNO 26-inch refractors between 1967 and 1998. Specific procedures and algorithms are used to obtain highly accurate positions using the Tycho2, UCAC2 (20 - 30 mas) and later the UCAC3 (10 - 20 mas) catalogues. A comparison with the MAMA digitizer of the Paris Observatory is made through the results obtained from digital mosaic images of the plates.

Analytical modeling of soliton interactions in a nonlocal nonlinear medium analogous to gravitational force

NASA Astrophysics Data System (ADS)

Zeng, Shihao; Chen, Manna; Zhang, Ting; Hu, Wei; Guo, Qi; Lu, Daquan

2018-01-01

We illuminate an analytical model of soliton interactions in lead glass by analogizing to a gravitational force system. The orbits of spiraling solitons under a long-range interaction are given explicitly and demonstrated to follow Newton's second law of motion and the Binet equation by numerical simulations. The condition for circular orbits is obtained and the oscillating orbits are proved not to be closed. We prove the analogy between the nonlocal nonlinear optical system and gravitational system and specify the quantitative relation of the quantity between the two models.

Closeup detail of the jackstand head and the attach mechanism ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Close-up detail of the jack-stand head and the attach mechanism connection to the hoist attach point on the starboard forward fuselage of the Orbiter Discovery. Note the profile of the wing intersection with the fuselage and the payload bay door in an open position with the strongback support structure attached. This view was taken from a service platform in the Orbiter Processing Facility at Kennedy Space Center. - Space Transportation System, Orbiter Discovery (OV-103), Lyndon B. Johnson Space Center, 2101 NASA Parkway, Houston, Harris County, TX

Closeup view of the underside of the forward fuselage of ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Close-up view of the underside of the forward fuselage of the Orbiter Discovery looking at the nose landing-gear and into the landing-gear well. The vehicle is elevated and supported by jack stands attached to the hoist attach points and the rear External Tank attach points on the propellant disconnect plate assemblies. This photo was taken inside the Orbiter Processing Facility at Kennedy Space Center. - Space Transportation System, Orbiter Discovery (OV-103), Lyndon B. Johnson Space Center, 2101 NASA Parkway, Houston, Harris County, TX