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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 145 records · Page 8
All sourcesNASA NTRSDOE OSTI
NASA NTRS1982

July 29, 1977, magnetospheric studies - Impulsive waves, global dynamics and geomagnetic indices

Problems of magnetospheric physics addressed by the Coordinated Data Analysis Workshop are grouped into general areas. Immediate magnetospheric response to changes in the solar wind is considered in studies of impulsive waves traced through the magnetosphere to the ground, and interpreted in terms of fast-mode wave propagation. Magnetopause geometry and microstructure after the arrival of the interplanetary shock were analyzed with data from near-geostationary satellites. A model of particle convection during the first quarter of the day gave important evidence that the convection electric field penetrated to small radial distances for extended intervals, and another model is presented which relates the local time of substorm onset to the sector of the tail that was stressed immediately after the onset of daytime reconnection. The evidence for different reconnection patterns is assessed, and a pattern not previously considered is introduced.

Kivelson, M. G.↗
NASA NTRS1983

Night-time observations of snow using visible imagery

Consideration is given to the possibility of increasing the frequency of satellite snow cover observations in the visible range by using the light reflected off the moon as an illumination source for nighttime observations. Images obtained at night by DMSP satellites orbiting in the noon-midnight plane are presented which were obtained at various phases of the moon. It is concluded that DMSP visible imagery can be used to detect snow cover during those periods when the moon is over the local horizon and is between the first quarter phase and the last quarter phase, which amounts to around five additional days a month allowing for cloud cover. The high frequency of observation of a given area provided by a light-sensitivity imager would be an important feature of a dedicated water-resources satellite.

Foster, J. L.↗
NASA NTRS1985

USSR Space Life Sciences Digest, issue 1

The first issue of the bimonthly digest of USSR Space Life Sciences is presented. Abstracts are included for 49 Soviet periodical articles in 19 areas of aerospace medicine and space biology, published in Russian during the first quarter of 1985. Translated introductions and table of contents for nine Russian books on topics related to NASA's life science concerns are presented. Areas covered include: botany, cardiovascular and respiratory systems, cybernetics and biomedical data processing, endocrinology, gastrointestinal system, genetics, group dynamics, habitability and environmental effects, health and medicine, hematology, immunology, life support systems, man machine systems, metabolism, musculoskeletal system, neurophysiology, perception, personnel selection, psychology, radiobiology, reproductive system, and space biology. This issue concentrates on aerospace medicine and space biology.

Hooke, L. R.↗
NASA NTRS1987

Ka-band (32-GHz) downlink capability for deep space communications

The first quarter century of U.S. solar system exploration using unmanned spacecraft has involved progressively higher operating frequencies for deep space telemetry: L-band (960 MHz) in 1962 to S-band (2.3 GHz) in 1964 to X-band (8.4 GHZ) in 1977. The next logical frequency to develop for deep space is the Ka-band (32 GHz) for which a primary deep space allocation of 500 MHz between 31.8 to 32.3 GHz was established in 1979. The telecommunications capability was improved by a factor of 77 (18.9 dB) through the frequency changes from L-band to X-band. Another improvement factor of 14.5 (11.6 dB) can be achieved by going to Ka-band. Plans to develop and demonstrate Ka-band capability include the continued measurement of weather effects at Deep Space Network (DSN) sites, development of a prototype DSN ground antenna and supporting subsystems, augmentation of planned spacecraft with Ka-band beacons, and development of spacecraft prototype modules for future Ka-band transmitters. Plans for augmenting the DSN with Ka-band capability by 1995 were also developed. A companion set of articles describes the Ka-band performance and technology in greater detail.

Smith, J. G.↗
NASA NTRS1986

System concept for a moderate cost Large Deployable Reflector (LDR)

A study was carried out at JPL during the first quarter of 1985 to develop a system concept for NASA's LDR. Major features of the concept are a four-mirror, two-stage optical system; a lightweight structural composite segmented primary reflector; and a deployable truss backup structure with integral thermal shield. The two-stage optics uses active figure control at the quaternary reflector located at the primary reflector exit pupil, allowing the large primary to be passive. The lightweight composite reflector panels limit the short-wavelength operation to approximately 30 microns but reduce the total primary reflector weight by a factor of 3 to 4 over competing technologies. On-orbit thermal analysis indicates a primary reflector equilibrium temperature of less than 200 K with a maximum gradient of about 5 C across the 20-m aperture. Weight and volume estimates are consistent with a single Shuttle launch, and are based on Space Station assembly and checkout.

Swanson, P. N.↗
NASA NTRS1988

Space station mobile transporter

The first quarter of the next century will see an operational space station that will provide a permanently manned base for satellite servicing, multiple strategic scientific and commercial payload deployment, and Orbital Maneuvering Vehicle/Orbital Transfer Vehicle (OMV/OTV) retrieval replenishment and deployment. The space station, as conceived, is constructed in orbit and will be maintained in orbit. The construction, servicing, maintenance and deployment tasks, when coupled with the size of the station, dictate that some form of transportation and manipulation device be conceived. The Transporter described will work in conjunction with the Orbiter and an Assembly Work Platform (AWP) to construct the Work Station. The Transporter will also work in conjunction with the Mobile Remote Servicer to service and install payloads, retrieve, service and deploy satellites, and service and maintain the station itself. The Transporter involved in station construction when mounted on the AWP and later supporting a maintenance or inspection task with the Mobile Remote Servicer and the Flight Telerobotic Servicer is shown.

Renshall, James↗
NASA NTRS1988

Advanced Technology Space Station studies at Langley Research Center

The paper describes the Advanced Technology Space Station systems studies at Langley Research Center, which were initiated to identify the technologies required for the construction of a high-performance station in the first quarter of the 21st century. Technologies which would maximize the synergistic effects between the subsystems and structural configurations were selected. The ECLSS and propulsion systems show promising synergistic relationships in the areas of oxygen and hydrogen production and attitude control.

Ferebee, Melvin J., Jr.↗
NASA NTRS1990

Observations of potassium in the tenuous lunar atmosphere

Observations of neutral potassium (K) in the tenuous lunar atmosphere are described. An echelle spectrograph, CCD, and data acquisition system are used to obtain emission spectra of neutral K atoms in the lunar atmosphere as observed by the 1.54 telescope at the Catalina Observatory at first quarter the night of April 29, 1989. A table of relevant lunar atmosphere parameters summarizes the results of the investigation. It is found that the number density at the surface is 9.5 + or - 1 atoms per cu cm and that there is a large nonthermal component and a deficiency of atoms equilibrated to the surface temperature. The calculated thermalization rate of the nonthermal component through encounters with the lunar surface gives a source of strength for the thermal component factor of 7 greater than loss by photoionization. Possible explanations for the low thermalized population observed are considered.

Kozlowski, Richard W. H.↗
NASA NTRS1992

Earth-based analogs of lunar and planetary facilities

Antarctica contains areas where the environment and terrain are more similar to regions on the Moon and Mars than any other place on Earth. These features offer opportunities for simulations to determine performance capabilities of people and machines in harsh, isolated locales. The Sasakawa International Center for Space Architecture (SICSA) plans to create a facility on Antarctica for research, planning, and demonstrations in support of planetary exploration. The Antarctic Planetary Testbed (APT) will be financed and utilized by public and private organizations throughout the world. Established on a continent owned by no country, it can serve as a model for cooperation between spacefaring nations. APT science and technology programs will expand knowledge about the nature and origin of our solar system, and will support preparations for human settlements beyond Earth that may occur within the first quarter of the next century. The initial APT facility, conceived to be operational by the year 1992, will be constructed during the summer months by a crew of approximately 12. Six to eight of these people will remain through the winter. As in space, structures and equipment systems will be modular to facilitate efficient transport to the site, assembly, and evolutionary expansion. State-of-the-art waste recovery/recycling systems are also emphasized due to their importance in space.

Bell, Larry↗
NASA NTRS1992

Cold flow testing of the Space Shuttle Main Engine alternate turbopump development high pressure fuel turbine model

NASA's Marshall Space Flight Center has established a cold airflow turbine test program to experimentally determine the performance of liquid rocket engine turbopump drive turbines. Testing of the SSME alternate turbopump development (ATD) fuel turbine was conducted for back-to-back comparisons with the baseline SSME fuel turbine results obtained in the first quarter of 1991. Turbine performance, Reynolds number effects, and turbine diagnostics, such as stage reactions and exit swirl angles, were investigated at the turbine design point and at off-design conditions. The test data showed that the ATD fuel turbine test article was approximately 1.4 percent higher in efficiency and flowed 5.3 percent more than the baseline fuel turbine test article. This paper describes the method and results used to validate the ATD fuel turbine aerodynamic design. The results are being used to determine the ATD high pressure fuel turbopump (HPFTP) turbine performance over its operating range, anchor the SSME ATD steady-state performance model, and validate various prediction and design analyses.

Gaddis, Stephen W.↗
NASA NTRS1993

PTTI-aided ephemeris calculation and rapid data link acquisition for manned space flight

Complexity of future manned space flight mission control can be significantly reduced by integrating GPS, the PTTI source, into telemetry, tracking, and command (TT&C). Future telecommunications, space tracking electronic intelligence, metrology, navigation, and data acquisition will thereby be served, including: on-board ephemeris determination, reduced synchronization time for time division multiple access (TDMA) links, and in-flight clock calibration, increasing on-board autonomy and reducing ground support costs. Manned space transportation through the first quarter of the 21st century will probably depend on a mix of vehicles, including the Advanced Manned Launch System (AMLS), the Personnel Launch System (PLS), and continued use of the Shuttle Fleet. Precise Ephemeris is important on-board for mission success, status monitoring, also for rendezvous and docking. Use of GPS can eliminate ground based tracking/processing, enhancing autonomy and reducing communications bandwidth. GPS time can simplify complicated functions used in bandwidth efficient time division multiple access (TDMA) communications, such as: precise and realtime synchronization of receive reference timing, transmit-timing and acquisition control, unique synchronization word (UW) detection, and elastic buffering. High clock accuracy provides increased signal-to-noise (S/N) ratio during acquisition, permitting narrower acquisition frequency and time windows. Spaceborne systems requirements to provide capabilities such as: refinement of the GEM-72 gravity model based on satellite tracking observations from ATS-6 to GEOS-3, relativistic clock experiments, NASA crustal dynamics program for developing space geodetic techniques to study the earth's crust, its gravity field, and earthquake mechanisms, and multi-disciplinary space geodetic tracking for studying global climatic changes are also reviewed.

Anderman, Alfred↗
NASA NTRS1992

Surfactant studies for bench-scale operation

A phase 2 study was initiated to investigate surfactant-assisted coal liquefaction, with the objective of quantifying the enhancement in liquid yields and product quality. This publication covers the first quarter of work. The major accomplishments were: the refurbishment of the high-pressure, high-temperature reactor autoclave, the completion of four coal liquefaction runs with Pittsburgh #8 coal, two each with and without sodium lignosulfonate surfactant, and the development of an analysis scheme for the product liquid filtrate and filter cake. Initial results at low reactor temperatures show that the addition of the surfactant produces an improvement in conversion yields and an increase in lighter boiling point fractions for the filtrate.

Hickey, Gregory S.↗
NASA NTRS1992

Executive summary

The Astrotech 21 Optical Systems Technology Workshop was held in Pasadena, California on March 6-8, 1991. The purpose of the workshop was to examine the state of Optical Systems Technology at the National Aeronautics Space Administration (NASA), and in industry and academia, in view of the potential Astrophysics mission set currently being considered for the late 1990's through the first quarter of the 21st century. The principal result of the workshop is this publication, which contains an assessment of the current state of the technology, and specific technology advances in six critical areas of optics, all necessary for the mission set. The workshop was divided into six panels, each of about a dozen experts in specific fields, representing NASA, industry, and academia. In addition, each panel contained expertise that spanned the spectrum from x-ray to submillimeter wavelengths. This executive summary contains the principal recommendations of each panel. The six technology panels and their chairs were: (1) Wavefront Sensing, Control, and Pointing, Thomas Pitts, Itek Optical Systems, A Division of Litton; (2) Fabrication, Roger Angel, Steward Observatory, University of Arizona; (3) Materials and Structures, Theodore Saito, Lawrence Livermore National Laboratory; (4) Optical Testing, James Wyant, WYKO Corporation; (5) Optical Systems Integrated Modeling, Robert R. Shannon, Optical Sciences Center, University of Arizona; and (6) Advanced Optical Instruments Technology, Michael Shao, Jet Propulsion Laboratory, California Institute of Technology. This Executive Summary contains the principal recommendations of each panel.

Ayon, Juan A.↗
NASA NTRS1994

RINGSAT

Radio frequency interference (RFI) presents a serious problem to naval communications. Unauthorized transmissions on the same frequencies that FLTSAT or LEASAT use cause a loss of one or more transponders on a satellite. The problem is not correctable until the emitter is located and turned off, or until it runs off on its own. The present geolocation system cannot deal with the RFI problem adequately. This causes the Navy to lose operational capability and money. The proposed Radio Frequency Interference Navy Geolocation Satellite (RINGSAT) would locate the source of the interference within 3 hours, an outstanding improvement over current equipment. Furthermore, RINGSAT can be built quickly, at minimal cost, and can be used concurrently for other military missions. Currently, geolocation to identify the RFI is done at Naval Space Command. Using single satellite doppler, time delay of arrival, and frequency delay of arrival techniques, it is possible to locate the interfering emitter. However, for the first quarter of fiscal year 1993, about 50 different channels used by the Navy were nonoperational for over 500 hours. Almost 30 percent of the interference occurrences lasted for over 12 hours. In only one quarter of the cases was the interference turned off in less than two_hours either by our detection or on its own.

DOWDY↗
NASA NTRS1994

Variation of lunar sodium emission intensity with phase angle

We report new measurements of the sodium emission intensity seen in a line of sight just above the surface of the Moon. These data show a strong dependence on lunar phase. The emission intensity decreases from a maximum around first quarter (phase angle 90 deg) to very small values near full Moon (phase angle 0 deg). This suggests that the rate of sodium vapor production from the lunar surface is largest at the subsolar point and becomes small near the terminator. However, the sodium emission near full Moon falls below that which would be expected for solar photon-driven processes. Since the solar wind flux decreases substantially when the Moon enters the Earth's magnetotail near full Moon, while the global solar photon flux is undiminished, we suggest that solar wind sputtering is the dominant process for sodium production.

Potter, A. E.↗
NASA NTRS1995

Magnetic observations during the recent declining phase of solar activity

Changes in the heliospheric magnetic field during the recent declining phase in solar activity are reviewed and compared with observations during past sunspot cycles. The study is based principally on data obtained by IMP-8 and Ulysses. The field magnitude is found to have increased during the declining phase until it reached a maximum value of 11.5nT in approximately 1991.5, approximately two years after sunspot maximum. The field of the sun's south pole became negative after a reversal in early 1990. The sector structure disappeared at Ulysses in April 1993 when the latitude of the spacecraft was -30 deg revealing a low inclination of the heliospheric current sheet. A large outburst of solar activity in March 1991 caused four Coronal Mass Ejections (CMEs) and numerious shocks at the location of Ulysses. Following a delay of more than a year, a series of recurrent high speed streams and Corotating Interaction Regions commenced in July 1992 which were observed by IMP-8, Ulysses and Voyager 2. In all these respects, the behavior of the magnetic field mimics that seen in the two earlier sunspot cycles. The comprehensive data set suggests a correlation between the absolute value of B and sunspot number. The major solar cycle variations in the radial component (and magnitude) of the field have been successfully reproduced by a recent model consisting of a tilted solar dipole, whose strength and tilt undergo characteristic changes over the sunspot cycle, and the heliospheric current sheet. The large outbursts of activity in mid-1972, mid-1982 and the first quarter of 1991 may represent a characteristic last 'gasp' of solar activity before the sun evolves to a different state. The recurrent high speed streams in 1973, 1984 and 1992 accompany the developemnt of large asymetrical polar coronal holes and the growth in intensity of the polar cap fields. After they endure for about one year, the polar coronal holes recede and the high speed streams are replaced by weaker streams more characteristic of solar minimum.

Smith, E. J.↗
NASA NTRS1993

COMET: First mission progress

The COMmercial Experiment Transporter (COMET) is a set of hardware and related infrastructure used to support orbital experiments of the Commerical Centers for the Development of Space (CCDS's) and their industrial partners. During the three years since the program started, contracts have been signed, design reviews conducted on all components, experiments selected for the first mission, all hardware has been manufactured, the first phase of integrated testing of the satellite, the experiments, and the Launch Facility have all been completed. The program experienced several delays in 1993. A component failure in the Service Module during preparation for environmental testing in January resulted in an eight-week delay for the Service Module part of the FreeFlyer. Discovery of large overruns of the mass budget required a major revision of the mission profile for COMET 1. In the spring of 1993, Space Industries Incorporated (SII) and Westinghouse stopped work because of a lack of funds. EER continued to work toward completion of their launch systems. SII and Westinghouse resumed work in September 1993. Since resumption of work, a technical review of all systems to ascertain their state of readiness has been completed. No major problems were discovered. All systems are proceeding toward a launch date in the first quarter of 1994.

Pawlick, Joseph F., Jr.↗
NASA NTRS1998

Long-Term Global Morphology of Gravity Wave Activity Using UARS Data

This is the first quarter's report on research to extract global gravity-wave data from satellite data and to model those observations synoptically. Preliminary analysis of global maps of extracted middle atmospheric temperature variance from the CRISTA instrument is presented, which appear to contain gravity-wave information. Corresponding simulations of global gravity-wave and mountain-wave activity during this mission period are described using global ray-tracing and mountain-wave models, and interesting similarities among simulated data and CRISTA data are noted. Climatological simulations of mesospheric gravity-wave activity using the HWM-03 wind-temperature climatology are also reported, for comparison with UARS MLS data. Preparatory work on modeling of gravity wave observations from space-based platforms and subsequent interpretation of the MLS gravity-wave product are also described. Preliminary interpretation and relation to the research objectives are provided, and further action for the next quarter's research is recommended.

Eckermann, Stephen D.↗