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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 541 records · Page 30
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NASA NTRS1984

Shuttle/Centaur Upper Stage Capability

A joint project to design, develop, procure, and produce Centaur upper stages for use with the Space Shuttle is discussed. A common Centaur G stage 6 meters (19.5 feet) in length is being jointly developed. A longer version designated Centaur G Prime is being developed by NASA to accomplish the Galileo and International Solar-Polar Mission flights in 1986. The Centaur G and G Prime will have the capability to place, respectively, approximately 4540 kilograms (10,000 pounds) and 5910 kilograms (13,000 pounds) into geosynchronous orbit from a standard Shuttle parking orbit of 278 kilometers (150 nautical miles) and Shuttle performance (lift) capability 29,500 kilograms (65,000 pounds). The advent of high energy upper stage capability in 1986 will permit space users and spacecraft developers to utilize spacecraft growth, stage combination concepts with storage modules, teleoperator systems, and other mission peculiar devices to satisfy complex mission demands. These capabilities should greatly enhance the usefulness of the space environment and stimulate mission planners toward conception of innovative means to meet ever increasing mission requirements.

Clark, H. J.↗
NASA NTRS1985

Charging of DMSP/F6 spacecraft in aurora on 10 January 1983

Spacecraft charging has been widely observed in geosynchronous orbit on the ATS-5 and ATS-6 pair and on the SCATHA spacecraft. An adequate theory for explaining the observations exist. Neither the data or theory can be exported to low polar orbit and its drastically different environment. Evidence of charging on the DMSP F6 spacecraft is presented. A simple model is set up explaining the observations. Two independent instruments on the spacecraft showed charging to a moderate (44 volts) negative potential. The selection spectrometer showed a flux of 2 billion electrons per sq. cm. sec. ster. peaked at 9.5 keV. This was marginally sufficient to overcome the flux of cold ambient ions. Charging calculations are presented showing where simplications are justified and where serious uncertainties exist. More serious charging is predicted for the Shuttle in polar orbit.

Besse, A. L.↗
NASA NTRS1985

Development of a continuous broad-energy-spectrum electron source

The development of a practical prototype, large-area, continuous-spectrum, multienergy electron source to simulate the lower energy (approx = 1 to 30 keV) portion of the geosynchronous orbit electron environment was investigated. The results of future materials-charging tests using this multienergy source should significantly improve the understanding of actual in-orbit charging processes and should help to resolve some of the descrepancies between predicted and observed spacecraft materials performance.

Adamo, R. C.↗
NASA NTRS1984

Results of the SCATHA ion composition experiment during the IMS

Hot plasma composition measurements of the near equatorial SCATHA spacecraft at geocentric distances of 5.3 to 7.8 RE, provided pitch angle distributions of ion composition in the vicinity of geosynchronous orbit. Pronounced pitch angle and spectral differences between ion species, and temporal variations within each species, are indicative of many of the complex source, energization, transport, and loss mechanisms at play in the magnetosphere. Ion populations of interest include field aligned ions below several keV which are primarily ionospheric; more energetic ions peaked at 90 deg pitch angle; and intense equatorially trapped ions below a few hundred eV, primarily protons. Ionospheric plasma is observed to take part in the substorm injection process, and there is evidence of an enhanced ionospheric source at the inner edge of the injection region.

Quinn, J. M.↗
NASA NTRS1984

Simultaneous observation of the plasma sheet in the near earth and distant magnetotail - ISEE-1 and ISEE-3

Particle data have been acquired by the 1981-025 and 1982-019 spacecraft at geosynchronous orbit, as well as ISEE-1 in the near earth geomagnetic tail, and ISEE-3 in the distant geomagnetic tail. These observations are supplemented by ground-based magnetograms from near local midnight stations. Attention is given to a substorm recovery phase, and to observations of ion beams at the plasma sheet boundary in the near earth and distant tail, respectively, which are found to flow in opposite directions.

Scholer, M.↗
NASA NTRS1984

Ion propulsion for communications satellites

In a recent study of potential applications for electric propulsion, it was determined that ion propulsion can provide North-South stationkeeping (NSSK) for communication satellites in geosynchronous orbit with appreciably less mass than chemical propulsion. While this finding is not new, the margin of benefit over advanced chemical propulsion technology depends strongly on the ion propulsion system specifications. Full advantage must be taken of the under-utilized stored energy available from the communication satellite's batteries. This paper describes a methodology for evaluating the benefits obtained in using ion propulsion for NSSK, both in terms of the mass reduction and its economic value.

Poeschel, R. L.↗
NASA NTRS1985

Correlated observations of substorm effects in the near-earth region and the deep magnetotail

Simultaneous observations of energetic particle measurements from the geosynchronous satellite 1982-019 and magnetic field, electron plasma, and energetic proton and electron measurements obtained with ISEE 3 in the deep tail are presented. The data are supplemented by ground magnetograms. A substorm occurred on March 22, 1983, close to 0300 UT as identified in the ground magnetograms and by a particle injection at geosynchronous orbit. About 10 min later, ISEE 3 observed (at a distance of approximately 130 RE in the deep tail) magnetic field, plasma, and energetic particle signatures consistent with the passage of a plasmoid. After the passage of the plasmoid the satellite enters shortly into a lobelike environment, in which an energetic proton beam is observed. High-resolution magnetic field data are indicative of small-scale structures in the postplasmoid plasma sheet. From the plasma sheet flow speed during the plasmoid's passage it is concluded that the 0300 UT substorm is responsible for its origin. This allows an approximate timing of the plasmoid release at a near-earth neutral line and of the plasma sheet recovery after substorm onset, and it indicates a close relationship between processes in the near-earth plasma sheet and the deep tail during substorms.

Scholer, M.↗
NASA NTRS1984

Progress in developing ultrathin solar cell blanket technology

A program was conducted to develop technologies for welding interconnects to three types of 50-micron-thick, 2 by 2-cm solar cells. Parallel-gap resistance welding was used for interconnect attachment. Weld schedules were independently developed for each of the three cell types and were coincidentally identical. Six 48-cell modules were assembled with 50-micron (nominal) thick cells, frosted fused-silica covers, silver-plated Invar interconnectors, and four different substrate designs. Three modules (one for each cell type) have single-layer Kapton (50-micron-thick) substrates. The other three modules each have a different substrate (Kapton-Kevlar-Kapton, Kapton-graphite-Kapton, and Kapton-graphite-aluminum honeycomb-graphite). All six modules were subjected to 4112 thermal cycles from -175 to 65 C (corresponding to over 40 years of simulated geosynchronous orbit thermal cycling) and experienced only negligible electrical degradation (1.1 percent average of six 48-cell modules).

Patterson, R. E.↗
NASA NTRS1984

Simulation of external and internal electrostatic discharges at the spacecraft system test level

Environmental test activities concerned with space plasma-caused charging and discharing phenomena are discussed. It is pointed out that the origin of such an electrostatic discharge (ESD) is charging of spacecraft dielectrics by an energetic plasma in geosynchronous orbit, Jupiter's magnetosphere, or other similar space environments. In dealing with environmental testing problems, it is necessary to define the location and magnitude of any ESD's in preparation for a subsequent simulation of the given conditions. Questions of external and internal charging are discussed separately. The environmental hazard from an external discharge can be assessed by viewing the dielectric surface as one side of a parallel plate capacitor. In the case of internal charging, the level of environmental concern depends on the higher energy spectrum of the ambient electrons.

Whittlesey, A.↗
NASA NTRS1984

The NASA Lithium Technology Program

NASA is sponsoring research to develop advanced primary and secondary lithium cells. Lithium cells are conducive to aerospace use because they have high specific energy, volumetric energy density, and long storage capability. The primary cell research is centered on the Li/SOCl2 system. It is in the late development stage and all effort is being placed on resolving safety problems. The secondary cell, which is in the development stage, is the Li/TiS2 system. The objective is to produce a 100 wh/kg cell capable of operating in a geosynchronous orbit for 10 years. The development of improved conductivity polymeric films for electrochemical use is also being investigated. The lightweight batteries will have many applications in space and are already being prepared for the 1986 Galileo mission to Jupiter.

Halpert, G.↗
NASA NTRS1984

A spacecraft in trouble - The rescue of the tracking and data relay satellite

A detailed mission history is presented for the rescue of the Tracking and Data Relay Satellite (TDRS) in 1983, in the wake of a faulty rocket stage burn after reaching apogee. The 2.5-ton spacecraft began to spin out of control at 180 deg/s, still attached to its booster stage. An anomaly analysis was conducted, together with an attitude control subsystem simulation, as a result of which maneuvers were conducted that succeeded in boosting TDRS to geosynchronous orbit, using despin from the sun mode, three-axis stabilization during booster burn, and finally return to the sun mode.

Staich, S.↗
NASA NTRS1985

JPL emergency support of TDRSS and compatible satellites

The Tracking and Data Relay Satellite System (TDRSS) will consist of three identical satellites in geosynchronous orbits and a dedicated ground receiving station. The first two satellites (TDRS East and TDRS West) will form the operational TDRS service network providing near-global real-time user satellite coverage. The third TDRS satellite will act as an in-orbit spare. Since the TDRSS satellite are supported by a single ground station, a method of providing emergency support for TDRS and user satellites is needed. The support to be provided by JPL's Deep Space Network is described.

Fanelli, N. A.↗
NASA NTRS1986

Radiation effects on high performance polymers

Polymer matrix materials are candidates for use in large space antennas and space platforms that may be deployed in geosynchronous orbit 22,500 miles above the Earth. A principal concern is the long term effects of an environment that is hostile to organic polymers, including high energy electromagnetic radiation, bombardment by charged particles, and large abrupt changes in temperature. Two polyarylene ethers which might be utilized as models for polymers in space applications were subjected to dosages of 70 keV electrons up to 3.4 x 10 to the 10th power rad. The irradiated films were then examined to determine the effects of the high-energy electrons.

Orwoll, R. A.↗
NASA NTRS1985

Earth to space dc to dc power transmission system utilizing a microwave beam as source of energy for electric propelled interorbital vehicles

The paper contributes to the credibility of an electric propelled interorbital transportation system by introducing a new low-mass source of continuous dc power for electric propulsion and illustrating how the source can be economically tied to an electric utility on earth by an electronically steered microwave beam. The new thin-film rectenna, which functions as the receiving end of an earth-to-space microwave power transmission system is described. It is easily fabricated, is over 80 percent efficient, has a specific mass of no more than 2 kilograms per kilowatt of continuous dc power output, and is well adapted for deployment in space. The paper then describes a complete system consisting of the interorbital vehicle and the microwave power transmission system that supplies it with power. A design scenario is used to obtain performance data from the system in terms of vehicle transfer times, payload fractions, and costs. Electric energy costs are found to be less than $1000 per kilogram of payload delivered to geosynchronous orbit from low-earth orbit.

Brown, W. C.↗
NASA NTRS1985

Space radiation effects on an elastomer-toughened epoxy-graphite composite

An elastomer-toughened epoxy-graphite composite system (CE339/T300) was evaluated for its potential durability in the space radiation environment. The physical and chemical response of this system was characterized following exposure to radiation doses equivalent to 20 to 30 years in geosynchronous orbit using 1 MeV electrons. The results show that electrons generate extensive crosslinking and embrittlement of the matrix. This embrittlement results in chemical and mechanical property changes that would limit the service life of this epoxy system in some space structure applications.

Sykes, G. F.↗
NASA NTRS1985

Introduction - Space Station and platform roles in supporting future space endeavors

The function of the Space Station and a platform is studied. The development of an earth observing instrument platform in a near-polar geosynchronous orbit to provide data about the earth is examined. The establishment of a permanently manned Space Station will allow development of commercial laboratories. Architectural requirements for servicing, transportation, and assembly on the Space Station are analyzed. The study of physiological and psychological effects due to weightlessness can be conducted on the Space Station. Developments in space knowledge and technology that are possible with the Space Station are discussed.

Herman, D. H.↗
NASA NTRS1986

SCATHA survey of high-level spacecraft charging in sunlight

The statistical occurrence of spacecraft charging at near-geosynchronous orbit in daylight is studied with reference to results of an experiment conducted on the SCATHA satellite. In particular, it is found that: (1) the external current that creates high negative satellite frame potentials is the high-energy electron current from the electron population with energies greater than about 30 keV; (2) the electron current to the satellite from particles with energies less than about 30 keV neither drives the frame potential nor provides the current to balance the high-energy populations; and (3) the ion current provided from the entire range of measured ions is also not the primary source of the balancing current.

Mullen, E. G.↗
NASA NTRS1986

Hard ACTS to follow

The Advanced Communications Technology Satellite (ACTS), the third phase of NASA's 30/20 GHz satellite communications program, is praised for its frugal usage of both the geosynchronous orbital arch and the frequency spectrum resources necessary for communications satellites. Its objective is to verify Ka-band satellite communications concepts and to develop a flight and ground system for validation of the multibeam communications proof-of-concept technologies. The ACTS ground segment (comprised of four types of terminals) is designed to compliment the spacecraft for the SS launch in 1989. Precise coordination between the ground and spacecraft segments is performed by the baseband processor (BBP), which is an in-orbit switchboard, and the tracking error word, which enables the ground terminals to remain synchronized with onboard timing. Fixed spot beams and scan beams, comprising the two types of spot beams used, both operate at the same frequency and hence, conserve frequency resources. In addition, the time division multiple access serves to enhance system efficiency. It is concluded that Ka-band satellites are a practical approach to the better usage of those resources potentially threatened by communications satellites. Comprehensive graphs and block diagrams of the system are included.

Moy, L.↗