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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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At least 325 records · Page 18
All sourcesNASA NTRSDOE OSTI
NASA NTRS1990

Long duration exposure facility solar illumination data package

A post flight solar illumination data package was created by the LDEF thermal analysis data group in support of the LDEF science office data group. The data presented was prepared with the Thermal Radiation Analysis System (TRASYS) program. Ground tracking data was used to calculate daily orbital beta angles for the calculation of resultant fluxes. This data package will be useful in calculation of solar illumination fluent for a variety of beta angle orbital conditions encountered during the LDEF mission.

Berrios, William M.↗
NASA NTRS1992

A summary of XB-70 sonic boom signature data

A compilation is provided of measured sonic boom signature data derived from 39 supersonic flights (43 passes) of the XB-70 airplane over the Mach number range of 1.11 to 2.92 and an altitude range of 30500 to 70300 ft. These tables represent a convenient hard copy version of available electronic files which include over 300 digitized sonic boom signatures with their corresponding spectra. Also included in the electronic files is information regarding ground track position, aircraft operating conditions, and surface and upper air weather observations for each of the 43 supersonic passes. In addition to the sonic boom signature data, a description is also provided of the XB-70 data base that was placed on electronic files along with a description of the method used to scan and digitize the analog/oscillograph sonic boom signature time histories. Such information is intended to enhance the value and utilization of the electronic files.

Maglieri, Domenic J.↗
NASA NTRS1991

The role of clocks in operating deep space missions

Operation of deep space missions requires stable frequency references and clocks to perform several mission critical functions. These references are used in generating the telecommunication links to maintain communications between earth and spacecraft, in generating accurate doppler, range, and very long baseline interferometry (VLBI) observables for determining the spacecraft's time varying position, and to generate on-board timing information for clocking out timed commands and time tagging instrument data. In addition, science applications exist, particularly those utilizing radio instrumentation, which can require additional functions and levels of performance. The design necessary to support these functions affects both the spacecraft and the ground tracking stations. This paper provides a brief description of these functions and some of the key requirements needed to support them.

S. W. Asmar↗
NASA NTRS1991

Mars Observer trajectory and orbit design

The Mars Observer launch, interplanetary, Mars orbit insertion, and mapping orbit designs are described. The design objective is to enable a near-maximum spacecraft mass to be placed in orbit about Mars. This is accomplished by keeping spacecraft propellant requirements to a minimum, selecting a minimum acceptable launch period, equalizing the spacecraft velocity change requirement at the beginning and end of the launch period, and constraining the orbit insertion maneuvers to be coplanar. The mapping orbit design objective is to provide the opportunity for global observation of the planet by the science instruments while facilitating the spacecraft design. This is realized with a sun-synchronous near-polar orbit whose ground-track pattern covers the planet at progressively finer resolution.

Beerer, Joseph G.↗
NASA NTRS1991

Mars Observer trajectory and orbit control

The Mars Observer mission will study Mars from a low-altitude orbit. During interplanetary cruise, propulsive maneuvers are required to ensure capture, with a secondary constraint to satisfy limits on the probability of impact with Mars. After capture, the spacecraft will be brought to a near-circular mapping orbit through a series of maneuvers. Mapping orbit maneuvers will be performed in order to follow a predetermined set of ground tracks and to maintain orbit altitude. This will allow accurate spacecraft command sequence generation and aid science planning throughout the mapping phase. Specific orbit control plans for the open and close of the launch period have been developed to meet these needs. This paper describes the control capabilities and the associated expected velocity changes for the mission.

Halsell, C. A.↗
NASA NTRS1991

Global environmental monitoring with the EOS multi-angle imaging spectroradiometer (MISR)

The MISR provides a unique opportunity for studying the ecology and climate of the earth through the acquisition of systematic, global multiangle imagery in reflected sunlight. MISR uses nine cameras: a nadir camera and two banks of four cameras each pointed forward and aftward along the spacecraft ground track to image the earth at +/-30.7, +/-45.6, +/-60.0, and +/-72.5 deg. Radiometrically calibrated images at each angle will be obtained in four spectral bands centered at 440, 550, 670, and 860 nm. MISR will take image data in two different spatial resolution modes: local mode, in which selected targets are observed with 240-m spatial sampling, and global mode, where the entire sunlit eEarth is observed continuously with 1.92-km sampling. The instrument is capable of acquiring global coverage every nine days.

Diner, D. J.↗
NASA NTRS1992

TOPEX/Poseidon orbit acquisition maneuver design

The current baseline injection orbit for the jointly sponsored NASA/CNES TOPEX/Poseidon mission is near-circular, approximately 30 km below the desired operational orbit altitude and at the operational orbit inclination. A baseline maneuver sequence to retarget from this injection orbit to the desired operational orbit has been designed based upon the expected worst-case 3-sigma injection and maneuver execution errors. The sequence requires seven maneuvers, including an initial calibration burn, and achieves the operational orbit with the desired ground track pattern in 30 days. A delay sensitivity analysis has been conducted to estimate the allowable operational delay for each maneuver without increasing the total orbit acquisition period. The baseline sequence provides back-ups for a one-revolution delay for each maneuver and one-day delay for most maneuvers. It is also shown that a higher injection orbit allows the maneuver sequence to achieve the operational orbit in 26 days under a worst-case scenario.

Bhat, Ramachandra S.↗
NASA NTRS1992

Errors In Synthetic-Aperture Interferometric Radiometry

Report presents analysis of errors in image of scene reconstructed from output of synthetic-aperture interferometric radiometer (SAIR). Receiving at typical frequency of 1.4 GHz, SAIR is airborne or spaceborne instrument including several antennas aimed at nadir and arrayed along line perpendicular to trajectory, such that antennas scan swath along ground track in "pushbroom" fashion. Streaks in reconstructed scene partly removed by image-enhancement techniques.

Ruf, Christopher S.↗
NASA NTRS1993

More About The PHIMAP

Report discusses some engineering problems arising in implementing system described in "Programmable Hyperspectral Imaging Mapper" (NPO-17794), a conceptual generic advanced spectral imaging system scanning in "pushbroom" fashion along ground track of airplane or orbiting spacecraft.

Cutts, James A.↗
NASA NTRS1992

Earth observation photography: Looking back 20 years after Skylab

A committee of trained classroom teachers, backed by a volunteer team of technical experts and academic advisors has developed a program for earth science based on photographs obtained from low earth orbit. In selecting targeting objectives, immediate note was made of the fact nearly one generation (20 years) has passed since the United States' ambitious SKYLAB program was conducted. A critical part of those missions was the acquisition of earth photography using a six camera, multi-spectral camera system. This objective was systematically furthered through the term of three separate crew visits to the Space Station. Not merely an exercise in randomly photographing the Earth below, the purpose of the Earth Resource Experiment Package (EREP) was to determine what kind, and how much, photographic data could be acquired of the broad variety of Earth features witnessed on the mission's ground track. The collection of 35,000 photos produced by EREP represents the most complete coverage of Earth. However, it remains under used. GAS 324 intends to revisit, and to add a tier of relevancy to this inventory. The photography of GAS 324 should allow a direct examination and comparison of the changes in the globe in the last 20 years. format in both coverage and quality. The photogra phy acquired by CAN DO should allow a direct examination and comparison of the changes that have occured to the Globe in the last twenty years.

Nicholson, James H.↗
NASA NTRS1990

Reusable Reentry Satellite (RRS): Recovery tradeoff study

The main objectives of the Recovery Tradeoff Study were as follows: (1) to determine whether a land or water recovery best suits RRS system requirements; (2) what type of terminal recovery system is best suited for the RRS; and (3) what are the recovery access timelines after system landing. Based on the trade parameters and evaluation criteria used in this study, the land-landing configuration has an advantage over the water-landing configuration. It is recommended that a land-landing configuration be developed assuming WSMR as the landing site. It is also recommended that natural orbits be used for low inclination missions and any orbit adjustments for landing site targeting be performed at the end of the mission. Near-integer orbits should be used for high inclination missions and allow orbital decay to precess the ground track over the landing site range.

Source record↗
NASA NTRS1993

Use of particle beams for lunar prospecting

A key issue in choosing the appropriate site for a manned lunar base is the availability of resources, particularly oxygen and hydrogen for the production of water, and ores for the production of fuels and building materials. NASA has proposed two Lunar Scout missions that would orbit the Moon and use, among other instruments, a hard X-ray spectrometer, a neutron spectrometer, and a Ge gamma ray spectrometer to map the lunar surface. This passive instrumentation will have low resolution (tens of kilometers) due to the low signal levels produced by natural radioactivity and the interaction of cosmic rays and the solar wind with the lunar surface. This paper presents the results of a concept definition effort for a neutral particle beam lunar mapper probe. The idea of using particle beam probes to survey asteroids was first proposed by Sagdeev et al., and an ion beam device was fielded on the 1988 Soviet probe to the Mars moon Phobos. During the past five years, significant advances in the technology of neutral particle beams (NPB) have led to a suborbital flight of a neutral hydrogen beam device in the SDIO-sponsored BEAR experiment. An orbital experiment, the Neutral Particle Beam Far Field Optics Experiment (NPB-FOX) is presently in the preliminary design phase. The development of NPB accelerators that are space-operable leads one to consider the utility of these devices for probing the surface of the Moon using gamma ray, X-ray, and optical/UV spectroscopy to locate various elements and compounds. We consider the utility of the NPB-FOX satellite containing a 5-MeV particle beam accelerator as a probe in lunar orbit. Irradiation of the lunar surface by the particle beam will induce secondary and back scattered radiation from the lunar surface to be detected by a sensor that may be co-orbital with or on the particle beam satellite platform, or may be in a separate orbit. The secondary radiation is characteristic of the make-up of the lunar surface. The size of the spot irradiated by the beam is less than 1 km wide along the ground track of the satellite, resulting in the potential for high resolution. The fact that the probe could be placed in polar orbit would result in global coverage of the lunar surface. The orbital particle beam probe could provide the basis for selection of sites for more detailed prospecting by surface rovers.

Toepfer, A. J.↗
NASA NTRS1992

HUD Guidance for the ASKA Experimental STOL Aircraft using Radar Position Information

The paper describes a high performance HUD guidance system installed on the experimental powered-lift STOL aircraft Aska. Since the maiden flight in October 1985, the HUD system has been used in all the flight tests. The HUD has an accurate flight path symbol generated by inertial velocity from the IRS which is updated by up-linked precision radar position data. The flight path symbol is very useful for precise approach and flare control for Aska which has large ground effects. A synthetic runway is also presented, which is conformal with the real runway, using the position data from the ground tracking radar system. Under instrument meteorological conditions, the pilot can approach and land using the HUD synthetic runway as well as in visual meteorological conditions. The HUD system proved to be a valuable aid to the pilot for all the Aska flight tests. A NASA Ames Research Center test pilot demonstrated touch down accuracy of less than 8 meters (peak to peak) for a series of three landings.

Yazawa, Kenji↗
NASA NTRS1993

Spectral characteristics of time-dependent orbit errors in altimeter height measurements

A mean reference surface and time-dependent orbit errors are estimated simultaneously for each exact-repeat ground track from the first two years of Geosat sea level estimates based on the Goddard Earth model (GEM)-T2 orbits. Motivated by orbit theory and empirical analysis of Geosat data, the time-dependent orbit errors are modeled as 1 cycle per revolution (cpr) sinusoids with slowly varying amplitude and phase. The method recovers the known 'bow tie effect' introduced by the existence of force model errors within the precision orbit determination (POD) procedure used to generate the GEM-T2 orbits. The bow tie pattern of 1-cpr orbit errors is characterized by small amplitudes near the middle and larger amplitudes (up to 160 cm in the 2 yr of data considered here) near the ends of each 5- to 6-day orbit arc over which the POD force model is integrated. A detailed examination of these bow tie patterns reveals the existence of daily modulations of the amplitudes of the 1-cpr sinusoid orbit errors with typical and maximum peak-to-peak ranges of about 14 cm and 30 cm, respectively. The method also identifies a daily variation in the mean orbit error with typical and maximum peak-to-peak ranges of about 6 and 30 cm, respectively, that is unrelated to the predominant 1-cpr orbit error. Application of the simultaneous solution method to the much less accurate Geosat height estimates based on the Naval Astronautics Group orbits concludes that the accuracy of POD is not important for collinear altimetric studies of time-dependent mesoscale variability (wavelengths shorter than 1000 km), as long as the time-dependent orbit errors are dominated by 1-cpr variability and a long-arc (several orbital periods) orbit error estimation scheme such as that presented here is used.

Chelton, Dudley B.↗
NASA NTRS1992

Gravity field estimation from future space missions - TOPEX/POSEIDON, Gravity Probe B, and ARISTOTELES

Accurate knowledge of the gravity field is a firm requirement in any study of Planet Earth. Space techniques have so far demonstrated their superiority in the global mapping of the gravity field based on ground tracking and altimeter data mostly. Numerical and analytical simulation studies of the upcoming geophysically relevant missions that will most likely carry GPS receivers, indicate significant improvements in the accuracy as well as the resolution of the gravity field. TOPEX will improve by some two orders of magnitude the long wavelength part (to degree about 20), while GP-B will contribute in the long as well as medium wavelength part of the spectrum (up to degree about 60). The gradiometer measurements on ARISTOTELES will contribute in the medium and short wavelength regions (from degree 30 up); GPS tracking of the spacecraft though will provide additional information for the long wavelength gravity and will help resolve it to accuracies comparable to those obtained from GP-B. With the mean rms coefficient error per degree kept below 10 exp -10, geophysical signals such as the post-glacial rebound, tidal variations, and secular and periodic variations of the zonal field rise above the noise level and become readily observable processes.

Pavlis, Erricos C.↗
NASA NTRS1993

Visual Earth observation performance in the space environment. Human performance measurement 4: Flight experiments

A wide variety of secondary payloads have flown on the Space Transportation System (STS) since its first flight in the 1980's. These experiments have typically addressed specific issues unique to the zero-gravity environment. Additionally, the experiments use the experience and skills of the mission and payload specialist crew members to facilitate data collection and ensure successful completion. This paper presents the results of the Terra Scout experiment, which flew aboard STS-44 in November 1991. This unique Earth Observation experiment specifically required a career imagery analyst to operate the Spaceborne Direct-View Optical System (SpaDVOS), a folded optical path telescope system designed to mount inside the shuttle on the overhead aft flight deck windows. Binoculars and a small telescope were used as backup optics. Using his imagery background, coupled with extensive target and equipment training, the payload specialist was tasked with documenting the following: (1) the utility of the equipment; (2) his ability to acquire and track ground targets; (3) the level of detail he could discern; (4) the atmospheric conditions; and (5) other in-situ elements which contributed to or detracted from his ability to analyze targets. Special emphasis was placed on the utility of a manned platform for research and development of future spaceborne sensors. The results and lessons learned from Terra Scout will be addressed including human performance and equipment design issues.

Huth, John F.↗
NASA NTRS1993

Corvid meteoroids and a Giordano Bruno ray are genetically related

Both Corvid meteoroids and the Giordano Bruno (GB) crater are products of recent events. On June 25, or 26, 1178, Corvid meteoroids and a portion of GB ejecta were at the same place in the Solar System and moved in the same direction (right ascension = 12 degrees and declination = +19 degrees). The ground track of this direction is the same as that of the most prominant GB ray (azimuth = 237 degrees). These 'coincidences' could not have occurred by change and, therefore, support the conclusions that the GB impact occurred on June 26, 1178, and that Corvid meteoroids are high-velocity ejecta fragments from that impact. Finally, those fragments ejected with somewhat lower velocities failed to escape from the Earth-Moon system and produced the prominant ray extending southwest from the GB crater. Between June 25 and July 2, 1937, a Corvid meteor shower was observed. The apparent lack of Corvid showers in other years suggests that Corvids are the product of a recent break-up event. The right ascension and declination, corrected for zenith attraction, of 192 degrees and -19 degrees were reported for the radiant of this shower. This corresponds to a right ascension and declination of the direction of motion of Corvid meteoroids of 12 degrees and +19 degrees. In ecliptic coordinates the celestial longitude and latitude of this direction are 18 degrees and +13 degrees.

Hartung, Jack B.↗
NASA NTRS1993

Thermogeologic mapping of the Moon from lunar orbit

The Infrared Scanning Radiometer (ISR) onboard the Apollo 17 Command-Service Module (CSM) mapped thermal emission of the lunar surface from orbit. Measured temperature values span the diurnal range of lunar temperatures (85 K to 400 K) and have an accuracy of approximately plus or minus 2 K. Surface spatial resolution at nadir is 2.2 km. This Apollo data is being revisited using data presentation software for the Macintosh computer, which was not available 20 years ago, even on mainframes. The new thermal images exhibit subtleties in the delineation of geophysical surface units that were unappreciated in the original survey of the data. Looking first at nighttime thermal emission from the ground tracks over Oceanus Procellarum to Mare Orientale, we have confirmed and expanded on earlier observations of regolith differences between mare and highlands and of a scheme for relative age-dating of larger impact craters of the Copernican age. We see an impact crater near Lenz, just north of Orientale, which exhibits an extraordinarily fresh ejecta blanket. Photography of this area is extremely poor, but we can see the feature in the Galileo data. We plan to derive geophysical surface properties of the overflown region using thermal models of regolith structures.

Mendell, W. W.↗