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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 253 records · Page 14
All sourcesNASA NTRSDOE OSTI
NASA NTRS1966

Aero-Astrodynamics Research Review no. 5

Research in fields of aerodynamics, orbit flight mechanics, atmospheric physics, electromagnetic theory, aerothermodynamics, control systems, instrumentation, selenography, and structures

INSTRUMENTATION↗
NASA NTRS1974

Six-degree-of-freedom program to optimize simulated trajectories (6D POST). Volume 1: Formulation manual

The basic equations and models used in a computer program (6D POST) to optimize simulated trajectories with six degrees of freedom were documented. The 6D POST program was conceived as a direct extension of the program POST, which dealt with point masses, and considers the general motion of a rigid body with six degrees of freedom. It may be used to solve a wide variety of atmospheric flight mechanics and orbital transfer problems for powered or unpowered vehicles operating near a rotating oblate planet. Its principal features are: an easy to use NAMELIST type input procedure, an integrated set of Flight Control System (FCS) modules, and a general-purpose discrete parameter targeting and optimization capability. It was written in FORTRAN 4 for the CDC 6000 series computers.

Brauer, G. L.↗
NASA NTRS1978

Optimizing simulated trajectories

General-purpose rigid-body six-degrees-of-freedom program is used to solve wide variety of atmospheric flight mechanics and orbital transfer problems. Written for analysis of powered or unpowered vehicles operation near rotating oblate planet, typical applications include: guidance and flight-control system simulation and analysis, loads and dispersion-type analysis.

Brauer, G. L.↗
NASA NTRS1977

Orbit-orbit resonances among natural satellites

A qualitative physical description of the orbital resonance mechanism based on a previously published (Greenberg et al. 1972; Greenberg, 1973) mathematical analysis is presented. The fundamental principles of the resonance mechanism are illustrated by an examination of the Titan-Hyperion case. More complex resonances, including Enceladus-Dione, Mimas-Tethys are considered. Resonance phenomena involving the rings of Saturn, the inner three satellites of Uranus, and the inner three Galilean satellites of Jupiter are also discussed. The role of analyses of resonance phenomena in developing theories of satellite formation and evolution is examined.

Greenberg, R.↗
NASA NTRS1977

Orbit-orbit resonances in the solar system - Varieties and similarities

Descriptions of various orbit-orbit resonance mechanisms in the solar system are brought together in such a manner that the physical processes underlying the traditional mathematical presentations are apparent. A simple qualitative model based on the resonance between Saturn's satellites Titan and Hyperion is presented, the same resonance is analyzed quantitatively, and the small-eccentricity mechanism is examined. The following resonances are investigated in detail: Enceladus-Dione, Mimas-Tethys, Neptune-Pluto, and Rhea-Titan (secular resonance). Coupled librations of several asteroids near mean motions commensurable with Jupiter's are modeled, the Laplace relation involving Io, Europa, and Ganymede is studied, and the 1:1 resonance between the Trojan asteroids and Jupiter is discussed. Some higher-order commensurabilities involving asteroids are considered, including the 3:1 resonance between Alinda and Jupiter, the 13:5 resonance of Toro with Venus, the 8:5 resonance of Toro with earth, and the 11:28 resonance of Ivar with earth.

Greenberg, R.↗
NASA NTRS1978

Rate constants for the deactivation of O/1D/ by Xe, Kr, and Ar over the range 110-330 K

The rate constants for the deactivation of O(1D) by Xe, Kr, and Ar were measured over the range 110-330 K. Only Xe had a significant temperature dependence. Its Arrhenius expression is (8.5 + or - 1.7) times 10 to the -11th power exp(-103 + or - 52)/RT cu cm/molecule-sec. The rate constants for Kr and Ar are (6.4 + or - 1.3) times 10 to the -12th power and (5.0 + or - 1.5) times 10 to the -13th power cu cm/molecule-sec, respectively. The observed trend in deactivation efficiency, Xe (greatest), Kr, Ar (least), and the observed temperature effects support the results and the spin-orbit interaction mechanism for deactivation given by Husain and co-workers.

Davidson, J. A.↗
NASA NTRS1982

Mechanical properties of the Shuttle Orbiter thermal protection system strain isolator pad

An experimental investigation conducted to determine the static and fatigue properties of the Strain Isolator Pad (SIP) used on the Shuttle Orbiter Thermal protection system is described. Static tension-compression and shear test results show that the SIP is highly nonlinear and that it possesses a large hysteresis, a large low modulus region for low stress levels, and stress-strain properties that are highly sensitive to strain rate and previous load history. In addition, the shear properties are also found to be sensitive to forces applied normal to the plane of the pad and to the orientation of the material. For the undensified tile/SIP system, static and fatigue failure takes place at the SIP/tile interface at low stress levels and for a small number of cycles.

Sawyer, J. W.↗
NASA NTRS1985

In situ orbital debris experiment concepts

Implementation of the radar, lidar and passive optical remote sensing concepts for measuring space debris from an Earth orbiting platform was investigated. Each system was compared for their requirements on the host platform, their performance relative to the space debris measurement program and the estimated cost of developing each concept into a flight instrument. It is found that the radar and lidar systems offer the greatest versatility and accuracy since they control the direction, intensity and duration of the energy incident on the target object. The performance of the passive optical system is determined by the capability of the detector and by the baseline separation of the telescopes, which requires the use of an on-orbit deployment mechanism. The passive optical concept provides the largest total event rae, and includes significant detections of particle sizes greater than 10 cm to allow correlation with ground based observations of the larger particles. The event rate for the radar system is relatively constant with particle while the lidar system is slightly biased toward the smaller sizes. These event rate differences result from a combination of the debris flux size distribution and the variation of sensitive detection area with particle size for the three concepts.

Neste, S. L.↗
NASA NTRS1987

Microwave Properties of Quiet Seas

Microwave fluxes from three quiet seas documented for five microwave frequencies. Measurements taken by satellite in Earth orbit with mechanically scanned antenna. 10-channel receiver used to record simultaneously signal intensities in both horizontal and vertical polarizations at each frequency. Comparisons of flux measurements of three quiet seas drawn, and results discussed and analyzed.

Stacey, J. M.↗
NASA NTRS1989

Orbital evolution of circumplanetary dust by resonant charge variations

Vast ethereal rings composed of micron-sized particles have been detected about the three giant planets so far visited by Voyager. An orbital evolution mechanism for gravitationally dominated circumplanetary dust is identified here that may temporarily overwhelm other processes. Evolution rates that agree with numerical integrations are derived, and it is suggested how this process could affect the location of the faint rings evident today.

Burns, Joseph A.↗
NASA NTRS2000

Evaluation of Non-Ozone-Depleting-Chemical Cleaning Methods for Space Mechanisms Using a Vacuum Spiral Orbit Rolling Contact Tribometer

Because CFC 113, an ozone depleting chemical (ODC), can no longer be produced, alternative bearing cleaning methods must be studied. The objective of this work was to study the effect of the new cleaning methods on lubricant lifetime using a vacuum bearing simulator (spiral orbit rolling contact tribometer). Four alternative cleaning methods were studied: ultra-violet (UV) ozone, aqueous levigated alumina slurry (ALAS), super critical fluid (SCF) CO2 and aqueous Brulin 815GD. Baseline tests were done using CFC 113. Test conditions were the following: a vacuum of at least 1.3 x 10(exp -6) Pa, 440C steel components, a rotational speed of 10 RPM, a lubricant charge of between 60-75 micrograms, a perfluoropolyalkylether lubricant (Z-25), and a load of 200N (44.6 lbs., a mean Hertzian stress of 1.5 GPa). Normalized lubricant lifetime was determined by dividing the total number of ball orbits by the amount of lubricant. The failure condition was a friction coefficient of 0.38. Post-test XPS analysis was also performed, showing slight variations in post-cleaning surface chemistry. Statistical analysis of the resultant data was conducted and it was determined that the data sets were most directly comparable when subjected to a natural log transformation. The natural log life (NL-Life) data for each cleaning method were reasonably normally (statistically) distributed and yielded standard deviations that were not significantly different among the five cleaning methods investigated. This made comparison of their NL-Life means very straightforward using a Bonferroni multiple comparison of means procedure. This procedure showed that the ALAS, UV-ozone and CFC 113 methods were not statistically significantly different from one another with respect to mean NL-Life. It also found that the SCF CO2 method yielded a significantly higher mean NL-Life than the mean NL-Lives of the ALAS, UV-ozone and CFC 113 methods. It also determined that the aqueous Brulin 815GD method yielded a mean NL-Life that was statistically significantly higher than the mean NL-Lives of each of the other four methods. Baseline tests using CFC 113 cleaned parts yielded a mean NL-Life 3.62 orbits/micro-g. ALAS and UV-ozone yielded similar mean NL-Life (3.31 orbits/mg and 3.33 orbits/micro-g, respectively). SCF CO2, gave a mean NL-Life of 4.08 orbits/mg and aqueous Brulin 8l5GD data yielded the longest mean NL-Life (4.66 orbits/micro-g).

Jansen, Mark J.↗
NASA NTRS2003

STS-112 Mission Highlights Resource Tape, Part 1 of 3

This video, Part 1 of 3, shows the activities of the STS-112 crew on flight days 1 - 3. The crew included Commander Jeff Ashby, Pilot Pam Melroy, and Mission Specialists Sandy Magnus, David Wolf, Piers Sellers, and Fyodor Yurchikhin. Flight day 1 begins with an introduction of the astronauts, seen during their pre-flight banquet, and suit-up. The ingress of some of the crew into the Space Shuttle Atlantis is shown. The launch footage includes the view from a camera mounted on the shuttle's external fuel tank, as well as replays. The separation of the shuttle's booster rockets is also shown. On flight day 2 a view of the payload bay and orbiter docking mechanism on Atlantis is shown from a camera on the shuttle's robotic arm. The footage of flight day 3 includes the docking of Atlantis and the International Space Station (ISS), and the exchange of greetings between the two spacecrews. Views of Earth include a pass over the western United States on flight day 2, and a night view of China on flight day 3.

Source record↗