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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 181 records · Page 10
All sourcesNASA NTRSDOE OSTI
NASA NTRS1993

Satellite situation report, volume 33, number 2

This report consists of data computed at United States Space Command, GFSC, or provided by satellite owners. A space objects box score table is presented with data under the following headings: source/organization, objects in orbit, and decayed objects. The objects in orbit and decayed objects' headings have payload, debris, and total as subheadings. The bulk of the document is objects in orbit tables with data under the following headings: international designation, name, catalog number, source, launch date, period minutes, inclination, apogee (km), perigee (km) and notes.

Source record↗
NASA NTRS1992

Satellite situation report, volume 32, no. 4

This report consists of data computed at the U.S. Space Command, GSFC, or provided by satellite owners. A space objects box score table is presented with data under the following headings: source/organization, objects in orbit, and decayed objects. The objects in orbit and decayed objects headings have payload, debris, and total as subheadings. The bulk of the document is objects-in-orbit tables with data under the following headings: international designation, name, catalog number, source, launch date, period minutes, inclination, apogee (km), perigee (km), and notes.

Source record↗
NASA NTRS1992

Satellite situation report, volume 32, no. 1

This report consists of data computed at the U.S. Space Command, GSFC, or provided by satellite owners. A space objects box score table is presented with data under the following headings: source/organization, objects in orbit, and decayed objects. The objects in orbit and decayed objects headings have payload, debris, and total as subheadings. The bulk of the document is objects-in-orbit tables with data under the following headings: international designation, name, catalog number, source, launch date, period minutes, inclination, apogee (km), perigee (km), and notes.

Source record↗
NASA NTRS1992

Satellite situation report, volume 32, no. 2

This report consists of data computed at the U.S. Space Command, GSFC, or provided by satellite owners. A space objects box score table is presented with data under the following headings: source/organization, objects in orbit, and decayed objects. The objects in orbit and decayed objects headings have payload, debris, and total as subheadings. The bulk of the document is objects-in-orbit tables with data under the following headings: international designation, name, catalog number, source, launch date, period minutes, inclination, apogee (km), perigee (km), and notes.

Source record↗
NASA NTRS1991

Satellite situation report, volume 31, no. 4

This report consists of data computed at the U.S. Space Command, GSFC, or provided by satellite owners. A space objects box score table is presented with data under the following headings: source/organization, objects in orbit, and decayed objects. The objects in orbit and decayed objects headings have payload, debris, and total as subheadings. The bulk of the document is objects-in-orbit tables with data under the following headings: international designation, name, catalog number, source, launch date, period minutes, inclination, apogee (km), perigee (km), and notes.

Source record↗
NASA NTRS1993

Satellite situation report, volume 33, no. 3

This report consists of data computed at the U.S. Space Command, GSFC, or provided by satellite owners. A space objects box score table is presented with data under the following headings: source/organization, objects in orbit, and decayed objects. The objects in orbit and decayed objects headings have payload, debris, and total as subheadings. The bulk of the document is objects-in-orbit tables with data under the following headings: international designation, name, catalog number, source, launch date, period minutes, inclination, apogee (km), perigee (km), and notes.

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NASA NTRS1989

Space station contamination modeling

Current plans for the operation of Space Station Freedom allow the orbit to decay to approximately an altitude of 200 km before reboosting to approximately 450 km. The Space Station will encounter dramatically increasing ambient and induced environmental effects as the orbit decays. Unfortunately, Shuttle docking, which has been of concern as a high contamination period, will likely occur during the time when the station is in the lowest orbit. The combination of ambient and induced environments along with the presence of the docked Shuttle could cause very severe contamination conditions at the lower orbital altitudes prior to Space Station reboost. The purpose here is to determine the effects on the induced external environment of Space Station Freedom with regard to the proposed changes in altitude. The change in the induced environment will be manifest in several parameters. The ambient density buildup in front of ram facing surfaces will change. The source of such contaminants can be outgassing/offgassing surfaces, leakage from the pressurized modules or experiments, purposeful venting, and thruster firings. The third induced environment parameter with altitude dependence is the glow. In order to determine the altitude dependence of the induced environment parameters, researchers used the integrated Spacecraft Environment Model (ISEM) which was developed for Marshall Space Flight Center. The analysis required numerous ISEM runs. The assumptions and limitations for the ISEM runs are described.

Gordon, T. D.↗
NASA NTRS1976

Study of the decay and recovery of orbiting artificial space objects

The reentry of earth-orbiting space objects unconsumed in the atmosphere represents a potential hazard to populated areas of the earth. The Smithsonian Astrophysical Observatory has conducted a program called Moonwatch, whose purposes were to observe orbiting artificial satellites and reentries of space objects and, if possible, to recover and analyze reentered pieces. In addition, through observations of low-perigee objects, data obtained by Moonwatchers have been instrumental in defining some of the factors affecting satellite decay. The objectives of the program are presented, and the problems that enter into satellite-orbit and decay predictions are addressed. Moonwatchers contributed substantially to increasing an overall prediction capability, and some of the specific achievements over the 6-year period are cited.

Source record↗
NASA NTRS1980

Skylab orbital lifetime prediction and decay analysis

A record (from preflight planning to earth impact) of skylab's orbital lifetime predictions, its actual decay and analysis are presented. Skylab provided a unique opportunity to develop, confirm and check out procedures and computer programs used for predicting lifetime and reentry. It provided verification of aerodynamic environment which was predicted for several aerodynamic configurations. It also provided data on the density model's reaction to rapidly changing solar flux over relatively short time periods. The effects of solar flux (and the uncertainty in the solar flux predictions) on orbital lifetime are discussed.

Dreher, P. E.↗
NASA NTRS1986

Orbital period changes in massive X-ray binaries

Data from long-term pulse-timing observations of Cen X-3 are compiled and analyzed to determine the evolution of the orbital period, and the implications of the results for other massive X-ray binaries are discussed. Third-body effects, tidal effects, and mass-loss/transfer effects are considered as possible causes for the orbital-period decay observed in Cen X-3, and it is concluded that strong tidal coupling between the companion star and the orbital causes the period decay via orbital instability and/or mass loss. Applying these results to the Roche-lobe-overflow models of Savonije (1983), the evolutionary expansion rate of the Cen X-3 companion and the Roche-lobe shrinking rate are estimated as about 2 x 10 to the -7th/yr and about 1 x 10 to the -6th/yr, respectively, implying an X-ray lifetime of about 5000 yr. Estimates of the companion mass-change rate and period decay for Cen X-3 and four other objects are presented in a table.

Kelley, Richard L.↗
NASA NTRS1991

Satellite situation report, volume 31, number 1

Data computed at GSFC, NORAD, or provided by satellite owners is reported. A space objects box score is presented of objects in orbit and decayed objects. Data of objects in orbit is presented in tabular form and the table headings include name of the object, catalog number, source, launch date, period minutes, inclination, apogee KM., perigee KM., and transmitting frequency.

Source record↗
NASA NTRS1973

The tidal loss of satellite-orbiting objects and its implications for the lunar surface

The solar system is composed of numerous bodies orbiting the sun, and numerous satellites orbiting planets. However, no objects greater than a kilometer in diameter are known to orbit satellites. Theoretical arguments are used to show that most objects orbiting satellites ultimately would be destroyed by tidal interactions. This may explain why such objects have not been observed. These arguments are applied to objects orbiting the moon. The ages and sizes of most of the circular mare basins are compatible with the lifetimes and crater sizes expected for impacts by objects caught in decaying lunar orbits. The morphology of a few circular mare basins (Crisium, Serenitatis, and possibly Imbrium) indicates that they could have been formed by such impacts. Thus, the lunar surface may provide a record of impacts due to objects caught in tidally decaying lunar orbits.

Reid, M. J.↗
NASA NTRS1989

Lifetime predictions for the Solar Maximum Mission (SMM) and San Marco spacecraft

Lifetime prediction techniques developed by the Goddard Space Flight Center (GSFC) Flight Dynamics Division (FDD) are described. These techniques were developed to predict the Solar Maximum Mission (SMM) spacecraft orbit, which is decaying due to atmospheric drag, with reentry predicted to occur before the end of 1989. Lifetime predictions were also performed for the Long Duration Exposure Facility (LDEF), which was deployed on the 1984 SMM repair mission and is scheduled for retrieval on another Space Transportation System (STS) mission later this year. Concepts used in the lifetime predictions were tested on the San Marco spacecraft, which reentered the Earth's atmosphere on December 6, 1988. Ephemerides predicting the orbit evolution of the San Marco spacecraft until reentry were generated over the final 90 days of the mission when the altitude was less than 380 kilometers. The errors in the predicted ephemerides are due to errors in the prediction of atmospheric density variations over the lifetime of the satellite. To model the time dependence of the atmospheric densities, predictions of the solar flux at the 10.7-centimeter wavelength were used in conjunction with Harris-Priester (HP) atmospheric density tables. Orbital state vectors, together with the spacecraft mass and area, are used as input to the Goddard Trajectory Determination System (GTDS). Propagations proceed in monthly segments, with the nominal atmospheric drag model scaled for each month according to the predicted monthly average value of F10.7. Calibration propagations are performed over a period of known orbital decay to obtain the effective ballistic coefficient. Progagations using plus or minus 2 sigma solar flux predictions are also generated to estimate the despersion in expected reentry dates. Definitive orbits are compared with these predictions as time expases. As updated vectors are received, these are also propagated to reentryto continually update the lifetime predictions.

Smith, E. A.↗
NASA NTRS2000

Natural Hazards of the Space Environment

Spacecraft in Low Earth Orbit (LEO) are subject to numerous environmental hazards. Here I'll briefly discuss three environment factors that pose acute threats to the survival of spacecraft systems and crew: atmospheric drag, impacts by meteoroids and orbital debris, and ionizing radiation. Atmospheric drag continuously opposes the orbital motion of a satellite, causing the orbit to decay. This decay will lead to reentry if not countered by reboost maneuvers. Orbital debris is a by-product of man's activities in space, and consists of objects ranging in size from miniscule paint chips to spent rocket stages and dead satellites. Ionizing radiation experienced in LEO has several components: geomagnetically trapped protons and electrons (Van Allen belts); energetic solar particles; galactic cosmic rays; and albedo neutrons. These particles can have several types of prompt harmful effects on equipment and crew, from single-event upsets, latchup, and burnout of electronics, to lethal doses to crew.All three types of prompt threat show some dependence on the solar activity cycle. Atmospheric drag mitigation and large debris avoidance require propulsive maneuvers. M/OD and ionizing radiation require some form of shielding for crew and sensitive equipment. Limiting exposure time is a mitigation technique for ionizing radiation and meteor streams.

Evans, Steven W.↗
NASA NTRS1992

Practical aspects of on-orbit modal identification using free-decay data

This paper discusses practical aspects of performing on-orbit modal identification using time domain analysis of free-decay data. The effects of environmental constraints, structural characteristics, excitation, and sensing are reviewed. In a recent laboratory application, an on-orbit experiment is simulated using a limited number of excitation and measurement points. The identified modal parameters correlate well, though not uniquely, with those obtained in a complete modal survey. Practical difficulties in performing the correlation are illustrated.

Schenk, Axel↗