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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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NASA NTRS2002

Low Power Transceiver

One of the FREESTAR experiments, the Low Power Transceiver (LPT) experiment is a low-power, lightweight software programmable transceiver prototype technology demonstration that is being developed by NASA as a low-cost S-band spacecraft navigation and communication device. The LPT prototype receives Global Positioning System (GPS) satellite signals for spacecraft navigation support and provides both forward and return, low-rate data communications links to the Merritt Island (MILA) and Dryden Flight Research Facility (DFRC) ground stations and to the Tracking and Data Relay Satellite System (TDRSS). The experiment is designed to demonstrate the system's ability to do simultaneous communications and navigation, as well as multi-mode communications and reconfiguration. LPT is managed by NASA's Goddard Space Flight Center and sponsored by NASA/HQ Code M. The LPT experiment consists of one thermally conductive box containing the electronics stack, three S-band antennas and one L-band antenna. The LPT payload uses general Orbiter services, including power control, command, and telemetry provided through the HHC avionics. On-orbit, the LPT payload will be primarily operated via direct communications between LPT and ground stations (MILA, WLPS, or DFRC) and/or TDRSS, with backup command and telemetry capability provided via the hitchhiker avionics and remote Payload Operations Control Center. During operations, LPT will utilize high Sband frequencies for communications. The LPT TDRSS (and GN) forward link (uplink) frequency is 2106.40625 MHz and their TDRSS (and GN) return link (downlink) frequency is 2287.5 MHz (utilizing Left-handed Circular Polarization to work with the TDRSS MA system). Two standard switch panel switches will be utilized to prohibit inadvertent operation of the antenna. An additional inhibit will be provided through the HH avionics power relay to the LPT.

Source record↗
NASA NTRS1991

Sub-milliarcsecond determination of pole position using Global Positioning System data

The determination of pole-position variations from the analysis of 23 days of Global Positioning System (GPS) data continuously collected with a globally distributed, 21-station network is discussed. The comparison of the estimated pole positions from these data with results from 11 very long baseline interferometry (VLBI) experiments conducted during this same interval yields weighted root-mean-square differences about the mean differences of 0.5 mas for both X- and Y-pole position estimates from an analysis using single-day arcs, and 1.0 and 0.8 mas from an analysis using three weekly multiday arcs. These results are of sufficient quality that GPS could provide an alternative technique to VLBI and satellite laser ranging for regular monitoring of high-time-resolution variations in the position of the earth's rotation axis.

Herring, Thomas A.↗
NASA NTRS1983

Intercontinental time and frequency transfer using a global positioning system timing receiver

The Deep Space Network (DSN) has a requirement to maintain knowledge of the frequency offset between DSN stations within 3 x 10 to the -13th power and time offset within 10 microseconds. It is further anticipated that in the 1987-1990 era the requirement for knowledge of time offset between DSN stations will be less than 10 nanoseconds. The Jet Propulsion Laboratory (JPL) is using the Global Positioning System (GPS) Space Vehicles, as a development project, to transfer time and frequency over intercontinental distances between stations of the DSN and between the DSN and other agencies. JPL has installed GPS timing receivers at its tracking station near Barstow, California and at its tracking station near Madrid, Spain. The details of the experiment and the data are reported. There is a discussion of the ultimate capabilities of these techniques for meeting the functional requirements of the DSN.

Clements, P. A.↗
NASA NTRS1983

Intercontinental time and frequency transfer using a global positioning system timing receiver

The DSN has a requirement to maintain knowledge of the frequency offset between DSN stations with 3 x 10 to the minus 13th power and time offset within 10 microseconds. It is further anticipated that in the 1987-1990 era the requirement for knowledge of time offset between DSN stations will be less than 10 nanoseconds. JPL is using the Global Positioning System (GPS) Space Vehicles, as a development project, to transfer time and frequency over intercontinental distances between stations of the DSN and between the DSN and other agencies. JPL has installed GPS timing receivers at its tracking station near Barstow, California, and at its tracking station near Madrid, Spain. The details of the experiment and the data are reported. There is a discussion of the ultimate capabilities of these techniques for meeting the functional requirements of the DSN.

Clements, P. A.↗
NASA NTRS2007

Proceedings of the 20th International Symposium on Space Flight Dynamics

Topics include: Measuring Image Navigation and Registration Performance at the 3-Sigma Level Using Platinum Quality Landmarks; Flight Dynamics Performances of the MetOp A Satellite during the First Months of Operations; Visual Navigation - SARE Mission; Determining a Method of Enabling and Disabling the Integral Torque in the SDO Science and Inertial Mode Controllers; Guaranteeing Pointing Performance of the SDO Sun-Pointing Controllers in Light of Nonlinear Effects; SDO Delta H Mode Design and Analysis; Observing Mode Attitude Controller for the Lunar Reconnaissance Orbiter; Broken-Plane Maneuver Applications for Earth to Mars Trajectories; ExoMars Mission Analysis and Design - Launch, Cruise and Arrival Analyses; Mars Reconnaissance Orbiter Aerobraking Daily Operations and Collision Avoidance; Mars Reconnaissance Orbiter Interplanetary Cruise Navigation; Motion Parameters Determination of the SC and Phobos in the Project Phobos-Grunt; GRAS NRT Precise Orbit Determination: Operational Experience; Orbit Determination of LEO Satellites for a Single Pass through a Radar: Comparison of Methods; Orbit Determination System for Low Earth Orbit Satellites; Precise Orbit Determination for ALOS; Anti-Collision Function Design and Performances of the CNES Formation Flying Experiment on the PRISMA Mission; CNES Approaching Guidance Experiment within FFIORD; Maneuver Recovery Analysis for the Magnetospheric Multiscale Mission; SIMBOL-X: A Formation Flying Mission on HEO for Exploring the Universe; Spaceborne Autonomous and Ground Based Relative Orbit Control for the TerraSAR-X/TanDEM-X Formation; First In-Orbit Experience of TerraSAR-X Flight Dynamics Operations; Automated Target Planning for FUSE Using the SOVA Algorithm; Space Technology 5 Post-Launch Ground Attitude Estimation Experience; Standardizing Navigation Data: A Status Update; and A Study into the Method of Precise Orbit Determination of a HEO Orbiter by GPS and Accelerometer.

Woodard, Mark↗
NASA NTRS1984

Performance of the GPS package on Landsat-5

The Landsat-5 spacecraft, launched in March 1984, carries an experimental Global Positioning System Package (GPSPAC) as did Landsat-4 in 1982. The primary objective of this experiment was to characterize and improve the performance of GPSPAC as an onboard navigation tool. In order to validate the accuracy of GPSPAC orbit solutions, definitive Landsat-5 ephemerides, derived from ground based tracking data, were generated and compared with GPSPAC estimates. This paper presents the results of such analysis as well as a summary of GPSPAC operation on Landsat-5. A description of the Landsat-5 spacecraft, GPSPAC and its navigation algorithms are also included.

Heuberger, H.↗
NASA NTRS1999

The Ionosphere and Ocean Altimetry

The accuracy of satellite-based single-frequency radar ocean altimeters benefits from calibration of the total electron content (TEC) of the ionosphere below the satellite. Data from the global network of Global Positioning System (GPS) receivers provides timely, continuous, and globally well-distributed measurements of ionospheric electron content. We have created a daily automated process called Daily Global Ionospheric Map (Daily-GIM) whose primary purpose is to use global GPS data to provide ionospheric calibration data for the Geosat Follow-On (GFO) ocean altimeter. This process also produces an hourly time-series of global maps of the electron content of the ionosphere. This system is designed to deliver "quick-look" ionospheric calibrations within 24 hours with 90+% reliability and with a root-mean-square accuracy of 2 cm at 13.6 GHz. In addition we produce a second product within 72 hours which takes advantage of additional GPS data which were not available in time for the first process. The diagram shows an example of a comparison between TEC data from the Topographic Experiment (TOPEX) ocean altimeter and Daily-GIM. TEC are displayed in TEC units, TECU, where 5 TECU is 1 cm at 13.6 GHz. Data from a single TOPEX track is shown. Also shown is the Bent climatological model TEC for the track. Although the GFO satellite is not yet in its operational mode, we have been running Daily-GIM reliably (much better than 90%) with better than 2-cm accuracy (based on comparisons against TOPEX) for several months. When timely ephemeris files for the European Remote Sensing Satellite 2 (ERS-2) are available, daily ERS-2 altimeter ionospheric calibration files are produced. When GFO ephemeris files are made available to us, we produce GFO ionosphere calibration files. Users of these GFO ionosphere calibration files find they are a great improvement over the alternative International Reference Ionosphere 1995 (IRI-95) climatological model. In addition, the TOPEX orbit determination team at JPL has been using the global ionospheric maps to calibrate the single frequency GPS data from the TOPEX receiver, and report highly significant improvements in the ephemeris. The global ionospheric maps are delivered daily to the International GPS Service (IGS), making them available to the scientific community. Additional information is contained in the original.

Lindqwister, Ulf J.↗
NASA NTRS2023

Sea Ice Drift Tracks From Autonomous Buoys in the MOSAiC Distributed Network

A network of autonomous, ice-tethered buoys was deployed around the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) experiment in late September 2019 for a year-long drift in the Arctic Transpolar Drift Stream. The buoys were deployed as part of the MOSAiC distributed network (DN) which included 12 multi-instrumented ice stations and an additional 116 GPS buoys distributed primarily within a 40 km radius of the MOSAiC Central Observatory. Buoy coverage within the DN was maintained with additional deployments throughout the year-long drift allowing for collection of data over a full sea ice growth and melt cycle. All GPS position data from buoys deployed within the DN have been assembled and processed into the collection of 216 quality-controlled buoy drift tracks presented in this dataset covering the period 26 September 2019 – 23 May 2021. The drift tracks in this collection are ideal for studies of dynamic sea ice motion around the MOSAiC experiment at cascading spatial scales ranging from 100s of meters to 100s of km.

Angela C. Bliss↗
NASA NTRS1996

In search of cybernautics

This is a talk about the future of aviation in the information age. Ages come and go. Certainly the atomic age came and went, but the information age looks different. This talk reviews some recent experiments on navigation and control with the Global Positioning System. Vertical position accuracies within 1 foot have been demonstrated in the most recent experiments, and research emphases have shifted to issues of integrity, continuity, and availability. Inertial navigation systems (INS) contribute much to the reliability of GPS-based autoland systems. The GPS data stream can cease, and INS can still complete a precision landing from an altitude of 200 feet. The future of aviation looks like automatic airplanes communicating among each other to schedule ground assets and to avoid collisions and wake hazards. The business of the FAA will be to assure integrity of global navigation systems, to develop and maintain the software rules of the air, and to provide expert pilots to handle emergencies from the ground via radio control. The future of aviation is democratic and lends itself to personal airplanes. Some data analyses reveal that personal airplanes are just as efficient as large turbofan transports and just as fast over distances up to 1,000 miles, thanks to the decelerative influence of the hub and spoke system. Maybe by the year 2020, the airplane will rank with the automobile and computer as an agent of personal freedom.

Crow, Steven↗
NASA NTRS1999

Wind Speed Measurement from Bistatically Scattered GPS Signals

Instrumentation and retrieval algorithms are described which use the forward, or bistatically scattered range-coded signals from the Global Positioning System (GPS) radio navigation system for the measurement of sea surface roughness. This roughness is known to be related directly to the surface wind speed. Experiments were conducted from aircraft along the TOPEX ground track, and over experimental surface truth buoys. These flights used a receiver capable of recording the cross correlation power in the reflected signal. The shape of this power distribution was then compared against analytical models derived from geometric optics. Two techniques for matching these functions were studied. The first recognized the most significant information content in the reflected signal is contained in the trailing edge slope of the waveform. The second attempted to match the complete shape of the waveform by approximating it as a series expansion and obtaining the nonlinear least squares estimate. Discussion is also presented on anomalies in the receiver operation and their identification and correction.

Garrison, James L.↗
NASA NTRS2002

Global Positioning Svstem (GPS) on International Space Station (ISS) and Crew Return Vehicle (CRV)

Both the International Space Station and Crew Return Vehicle desired to have GPS on their vehicles due to improve state determination over traditional ground tracking techniques used in the past for space vehicles. Both also opted to use GPS for attitude determination to save the expense of a star tracker. Both vehicles have stringent pointing requirements for roll, pitch, and heading, making a sun or earth sensor not a viable option since the heading is undetermined. This paper discusses the technical challenges associated with the implementation of GPS on both of these vehicles. ISS and CRY use the same GPS receiver, but have faced different challenges since the mission of each is di fferent. ISS will be discussed first, then CRY. The flight experiments flown on the Space Shuttle in support of these efforts is also discussed.

Gomez, Susan F.↗
NASA NTRS1989

Contamination effects of GPS Navstar solar array performance

The solar arrays on Navstars 1 to 6 have been limiting the electrical power capabilities in the extended life (beyond the 5 year design life). The departure from predicted performance consists of an extra 2.5 percent per year degradation beyond the radiation model estimates. This degradation is unusual in showing a linear rather than exponential decay with time. The performance of the arrays on these satellites has been examined in order to predict future behavior and to make refined projections on the Navstar 7 to 11 solar arrays. Evidence obtained from flight experiments on Navstar 5 and 6, and from laboratory experiments, suggests that contamination of the solar arrays while on orbit may be responsible. The evidence for photo-induced contamination of spacecraft surfaces is presented, and the effect on solar array output in the case of the GPS satellites is shown to be consistent with the observed anomalies.

Marvin, Dean C.↗
NASA NTRS2008

Best Practices for Researching and Documenting Lessons Learned

Identification, resolution, and avoidance of technical and programmatic issues are important for ensuring safe and successful space missions. Although the importance of applying lessons learned to reduce risk is frequently stressed, there is little material available to help technical and management personnel research and document lessons learned. Collecting, researching, identifying, and documenting lessons learned that will be useful to current and future management and engineering personnel is not always a straightforward task. This white paper presents lessons learned and best practices concerning the research and documentation of technical and organizational lessons learned. It is intended to enable organizations to initiate or improve lessons learned research and documentation efforts. The content of this white paper is based on four technical lessons learned projects conducted by the United Space Alliance (USA) Flight Design and Dynamics Department, in support of the NASA/Johnson Space Center (JSC) Flight Design and Dynamics Division. Each project published a report, titled as follows: (1) GPS Lessons Learned From the ISS, Space Shuttle and X-38; (2) Lessons Learned From Seven Space Shuttle Missions; (3) Space Shuttle Rendezvous and Proximity Operations Experience Report; and (4) Navigation Technical History with Lessons Learned. The four projects were different in availability of subject matter experts and primary source material, subject scope, and the level of effort required to produce the final report. However, generic lessons can be drawn from all of them. The best practices will be discussed by the phases of report research and development: (1) Defining Report Requirements, Project Organization, and Schedule; (2) Collection and Analysis of Source Material; (3) Writing and Integrating the Report; and (4) Review and Revision of the Report.

Goodman, John L.↗
NASA NTRS2020

Comparison of Vertical Surface Deformation Estimates Derived From Space-Based Gravimetry, Ground-Based GPS, and Model-Based Hydrologic Loading Over Snow-Dominated Watersheds in the United States

Spatiotemporal variability in Earth's terrestrial water storage (TWS) causes changes in surface deformation. The potential for using ground-based Global Positioning System (GPS) vertical displacement observations for estimating TWS is explored through a comparison of vertical displacements derived from space-based gravimetric retrievals, ground-based GPS, and model-based hydrologic estimates. The study presented here focuses on two snow-dominated basins in the Western United States for the years 2003–2016. Seasonal variations are observed in the vertical displacements derived from all three data sets, and the variation is coherent with the changes in hydrologic loading. Good consistency is observed between any two of the three data sets with gravimetric retrievals and hydrologic model estimates providing the highest level of agreement (i.e., all examined stations with correlation coefficient R > 0.70). Vertical displacements derived from gravimetric retrievals and ground-based GPS yielded R > 0.70 for more than 89% of the stations. In addition, it is found that both GPS-derived and space-based, gravimetry-derived vertical displacements clearly reflected the impact of climate variation (i.e., heavy precipitation during 2010–2011 winter followed by prolonged drought). Vertical displacements derived from the hydrologic model highlighted the relatively large precipitation convergence phase during late 2010 to early 2011 at some stations but not the prolonged drought that followed. The results indicate that ground-based GPS observations of vertical displacement have the capability to capture variations in TWS changes, which can be systematically merged in conjunction with Gravity Recovery and Climate Experiment (GRACE) into a land surface model to improve TWS estimates in a follow-up study.

Gaohong Yin↗
NASA NTRS1991

JPL 1990-3: A 5-nrad extragalactic source catalog based on combined radio interferometric observations

A combined analysis merges 17,000 Deep Space Network (DSN) Very Long Baseline Interferometric (VLBI) observations with 303,000 observations from the Crustal Dynamics Project (CDP) and the International Radio Interferometric Surveying (IRIS) project. Observations from the Radio Reference Frame Development (RRFD) and Time and Earth Motion Precision Observations (TEMPO) programs through late 1990 form the DSN VLBI data set. The combined analysis yields angular coordinates of extragalactic radio sources with a precision of a few nanoradians, as compared with 5 to 10 nrad precision for coordinates derived in the past solely from DSN data. The improvement in the combined analysis is due to the new Mark III DSN data, as well as to increased statistical strength from the large volume of observations from non-DSN experiments. Such a unified analysis is made possible by recent improvements in parameter estimation software efficiency. The terrestrial reference frame is based on joint VLBI experiments using both DSN and CDP antennas, and on specifying the coordinates of VLBI antennas in a proper geocentric coordinate system by means of Global Positioning System (GPS) collocation of VLBI, LLR, and SLR (Laser Ranging) sites.

Sovers, O. J.↗
NASA NTRS2000

Propulsive Small Expendable Deployer System (ProSEDS)

The Propulsive Small Expendable Deployer System (ProSEDS) space experiment will demonstrate the use of an electrodynamic tether propulsion system to generate thrust in space by decreasing the orbital altitude of a Delta II Expendable Launch Vehicle (ELV) second stage. ProSEDS, which is planned to fly in 2001, will use the flight proven Small Expendable Deployer System (SEDS) to deploy a tether (5km bare wire plus 10 km spectra or dyneema) from a Delta II second stage to achieve approximately 0.4N drag thrust. ProSEDS will utilize the tether-generated current to provide limited spacecraft power. The ProSEDs instrumentation includes a Langmuir probe and Differential Ion Flux Probe, which will determine the characteristics of the ambient ionospheric plasma. Two Global Positioning System (GPS) receivers will be used (one on the Delta and one on the endmass) to help determine tether dynamics and to limit transmitter operations to occasions when the spacecraft is over selected ground stations, The flight experiment is a precursor to the more ambitious electrodynamic tether upper stage demonstration mission, which will be capable of orbit raising, lowering and inclination changes-all using electrodynamic thrust. An immediate application of ProSEDS technology is for the deorbit of spent satellites for orbital debris mitigation. In addition to the use of this technology to provide orbit transfer and debris mitigation it may also be an attractive option for future missions to Jupiter and any other planetary body with a magnetosphere.

Ballance, Judy↗
NASA NTRS2007

GRAS NRT Precise Orbit Determination: Operational Experience

EUMETSAT launched the meteorological satellite MetOp-A in October 2006; it is the first of the three satellites that constitute the EUMETSAT Polar System (EPS) space segment. This satellite carries a challenging and innovative instrument, the GNSS Receiver for Atmospheric Sounding (GRAS). The goal of the GRAS instrument is to support the production of atmospheric profiles of temperature and humidity with high accuracy, in an operational context, based on the bending of the GPS signals traversing the atmosphere during the so-called occultation periods. One of the key aspects associated to the data processing of the GRAS instrument is the necessity to describe the satellite motion and GPS receiver clock behaviour with high accuracy and within very strict timeliness limitations. In addition to these severe requirements, the GRAS Product Processing Facility (PPF) must be integrated in the EPS core ground segment, which introduces additional complexity from the data integration and operational procedure points of view. This paper sets out the rationale for algorithm selection and the conclusions from operational experience. It describes in detail the rationale and conclusions derived from the selection and implementation of the algorithms leading to the final orbit determination requirements (0.1 mm/s in velocity and 1 ns in receiver clock error at 1 Hz). Then it describes the operational approach and extracts the ideas and conclusions derived from the operational experience.

MartinezFadrique, Francisco M.↗
NASA NTRS2000

Parts Engineering Experiences, Philosophies and Trends

This document is the presentation viewgraphs of the NASA presentations to NASDA, outlining the philosophy and trends of the experiences with engineering parts. Included in the presentations: are (1) the assurance of COTS boards for Space flight, and (2) Peer Review for Ice, Cloud and land Elevation Satellite (ICESat) GPS flight receivers EEE parts. The emphasis is on the methods for qualification of available parts for space flight.

Shaw, Harry↗