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Cour-Palais, B. G.

Publications and source records attributed to Cour-Palais, B. G..

At least 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1992

Evaluation of Whipple Bumper shields at 7 and 10 km/s

A series of experiments has been performed on the Sandia Hypervelocity Launcher to determine the performance limits of conventional Whipple shields against representative 0.8 g aluminum orbital debris plate-like fragments with velocities of 7 and 10 km/s. Supporting diagnostics include flash X-rays, high speed photography and transient digitizers for timing correlation. Two Whipple shield designs were tested with either a 0.030 cm or a 0.127 cm thick front sheet and a 0.407 cm thick backsheet separated by 30.5 cm. These two designs bracket the ballistic penetration limit curve for protection against these debris simulants for 7 km/s impacts.

Ang, J. A.↗
NASA NTRS1989

A hypervelocity launcher for simulated large fragment space debris impacts at 10 km/s

The background, design, and testing of two explosive launchers for simulating large fragment space debris impacts are presented. The objective was to develop a launcher capable of launching one gram aluminum fragments at velocities of 10 km/s. The two launchers developed are based on modified versions of an explosive shaped charge, common in many military weapons. One launcher design has yielded a stable fragment launch of approximately one gram of aluminum at 8.93 km/s velocity. The other design yielded velocities in excess of 10 km/s, but failed to produce a cohesive fragment launch. This work is ongoing, and future plans are given.

Tullos, R. J.↗
NASA NTRS1989

Hypervelocity impacts and upper-stage breakups

Preliminary analysis results have been obtained for tests conducted to ascertain whether a distinctive fragmentation 'signature' allows discrimination between launch vehicle upper stage destructions due to hypervelocity particle impacts and internal explosions. An account is presently given of factors controlling the damage pattern created by hypervelocity impacts, and an evaluation is made of the applicability of the simulation results obtained to actual upper stage destruction characterization.

Cour-Palais, B. G.↗
NASA NTRS1985

Hypervelocity impact investigations and meteoroid shielding experience related to Apollo and Skylab

Generic hypervelocity impact related topics and specific Apollo/Skylab related investigations are reviewed. Cratering and spallation mechanisms and the relationships between the effecting physical parameters are discussed. Design and material requirements for meteoroid shielding structures are also addressed. Penetration resistance and failure mode studies for Apollo/Skylab components are reviewed.

Cour-Palais, B. G.↗
NASA NTRS1985

STS 8 Orbiter mission window pitting and the possible association with the El Chichon eruption of March and April 1982

The possibility that the pitting that occurred in the STS-8 Orbiter windows was caused by dust from the El Chichon volcano eruption in March-April 1982 is considered. The pit density was more than 30/sq cm, most being 2.5-5 microns deep, and showed no evidence of impact melting. An 'alley' of higher incidence of pits in one window coincided with the line of a seam between TPS tiles. The particles causing the sandblasting were concluded to have arrived in parallel and could not be attributed to the ET, SRBs or a dust storm. The sulfuric gas-rich El Chichon plume injected sufficient material into the atmosphere so that the globe was soon encircled. Most of the resulting particulates (480-8400 tons) stayed in the Northern Hemisphere, and H2SO4 and ash concentrations were high during the STS-8 mission. The Orbiter cut through the debris layer at 19.8 km altitude at a 10 deg angle of attack, which matches the particle crater impact angle in the Orbiter windows. Since the passage was at night, larger H2SO4 droplets may have coalesced and formed larger particles on available solid nuclei, thus producing the 20-40 microns cratering observed in the windows.

Cour-Palais, B. G.↗
NASA NTRS1980

Some significant considerations in the planning of sortie missions

Opportunities and limitations to be considered in the planning of Space Shuttle/Spacelab sortie missions are discussed. As shown by a simple model of the flow of STS equipment through ground processing and flights under ideal conditions, mission duration is constrained by Orbiter availability, which is determined initially by the Orbiter production schedule and the turnaround time required between missions, and by the usage rate and quantity limitations of mission consumables. Additional considerations affecting mission duration include reductions in crew productivity upon increased mission duration and crew size, spacecraft and experiment degradation, equipment and processing facility cost effectiveness, and requirements for a power extension package, which considerations imply that increased allowable landing weight would make co-manifesting (the combination of Spacelab and deliverable payload missions) more attractive. Advantages related to payload recoverability, human presence, ease of access and the availability of different orbits are also pointed out.

Loftus, J. P., Jr.↗
NASA NTRS1980

Collision avoidance in space

Collisions in earth orbital space between operational payloads and various forms of space debris (nonoperational payloads, nonfunctional mission-related objects and fragments resulting from collisions and explosions) are discussed and possible means of avoiding them are considered. From 10,000 to 15,000 objects are estimated to be in earth orbital space, most of which represent spacecraft fragments and debris too small to be detected and tracked by earth-based sensors, and it is considered likely that some of them will be or have already been involved in direct collisions with the ever increasing number of operational satellites and space stations. Means of protecting proposed large space structures and smaller spacecraft from significant damage by larger space objects, particularly in the 400-4000 km altitude range where most debris occurs, include structural redundancy and the double shielding of sensitive components. Other means of collision avoidance are the collection or relocation of satellites, rocket bodies and other objects by the Space Shuttle, the prevention of explosions and the disposal of spent rocket parts by reentry. Finally, a management structure would be required to administer guidelines for the prevention and elimination of space debris.

Kessler, D. J.↗
NASA NTRS1979

Space vehicle meteoroid shielding design

Design principles of spaced, multiwall meteoroid protection are investigated in the light of experimental data generated during the Apollo Program. The outer wall or shield is shown to be the most important element in the meteoroid-spacecraft interaction. The condition of the debris is primarily a function of the shock pressure, the melting points of the meteoroid and the shield, and the length of the meteoroid and thickness of the shield. Spacing between the walls is effective up to approximately 100 times the length of the meteoroid. The required thickness of the second wall is shown to be proportional to the meteoroid mass, velocity, and density, and to the spacing between the walls, taken with exponents dependent upon the condition of the debris. The effects of placing additional elements (insulation or honeycomb cells) between the two walls are discussed, and the efficiency of various protective configurations is presented. An analysis of the meteoroid protection proposed for the Comet Halley probe is included as an appendix.

Cour-Palais, B. G.↗
NASA NTRS1979

Results of the examination of the Skylab/Apollo windows for micrometeroid impacts

Examination of the Command Module windows of the Skylab/Apollo 3 and 4 spacecraft at 5x magnification resulted in the detection of 18 micrometeroid craters 80 microns and larger in diameter for an accumulated exposure time of 144 days. A 20x magnification examination of the windows of the Skylab/Apollo 4 spacecraft identified 6 such craters between 20 and 70 microns in diameter for 84 days exposure. As the Skylab was oriented such that its solar panels faced the sun continuously, the three windows examined had a fixed orientation also. The six small craters were all found on the window that faced in the solar direction. A cumulative flux per square centimeter per year is given for pit and spall diameters.

Cour-Palais, B. G.↗
NASA NTRS1973

Apollo window meteoroid experiment

Apollo command module heat shield windows were examined for meteoroid impacts to obtain information about (1) the flux of meteoroids with masses of 10 to the -7th g and less, (2) dynamic and physical properties of meteoroids, and (3) correlations with lunar-rock-crater studies. The results of examining Apollo 17, and nine prior Apollo windows are tabulated. The window exposure time, number of impacts, crater diameter, flux, energy, and mass are shown.

Cour-Palais, B. G.↗
NASA NTRS1972

Apollo window meteoroid experiment

Apollo window meteoroid experiment for obtaining data from crater counts and analysis of meteoroid residue combined with fused glass in described. A preliminary estimate of the flux resulting from seven Apollo spacecraft is found to be in agreement with the Surveyor 3 data, but is lower than the model environment.

Cour-Palais, B. G.↗
NASA NTRS1972

Results of examination of the returned Surveyor 3 samples for particulate impacts

The television housing and a section of the strut of the radar altimeter and Doppler velocity sensor were examined optically and with a scanning electron microscope for particulate impacts. The white surface of the camera was discolored during the months the Surveyor 3 was on the moon; however, most of the craters must have occurred as a result of lunar dust sandblasted by the LM exhaust. The polished section of the strut exhibits contamination which appears brown and seems to be partially composed of crystals. Electron microscopic analysis of the strut section indicated no craters of hypervelocity impact origin, confirmed pitting density results of the optical scans, and indicated that material in the craters is of lunar origin. No meteorite impacts larger than 25 microns were detected on the tubing section.

Cour-Palais, B. G.↗
NASA NTRS1972

Apollo window meteoroid experiment

The Apollo window meteoroid experiment is described which uses the Apollo command module heat shield window surfaces to obtain information about the flux of meteoroids with masses of 10 to the minus 7th power g and less; to examine the residue and the morphology of the craters produced by these meteoroid; to obtain information regarding the dynamic and physical properties of the meteoroids; and to discover possible correlations with the lunar-rock-crater studies. Photographs are included.

Cour-Palais, B. G.↗
NASA NTRS1972

Meteoroid activity on the lunar surface from the Surveyor 3 sample examination.

The Surveyor 3 television camera shroud and polished aluminum tube, retrieved as a result of the Apollo 12 mission after 2.5 years on the lunar surface, were examined for evidence of meteoroid impact. Resulting estimates of the meteoroid flux in the lunar vicinity are shown to be in good agreement with the Lunar Orbiter penetration rates. In addition, the relationship between a derived lunar-surface meteoroid cumulative-flux model and the comparable near-earth model is discussed in the light of theoretical predictions. It is shown that the effect of the gravitational field of the earth on the near-earth environment was greater than previously predicted.

Cour-Palais, B. G.↗
NASA NTRS1971

Meteoroid activity on the lunar surface from the Surveyor 3 sample examination

The Surveyor 3 television camera shroud and polished aluminum tube, retrieved as a result of the Apollo 12 mission after 2-1/2 years on the lunar surface, were examined at the NASA Manned Spacecraft Center for evidence of meteoroid impact. The results of this examination were compared with other estimates of the meteoroid flux in the lunar vicinity and are shown to be in good agreement with the Lunar Orbiter penetration rates. In addition, the relationship between a derived lunar surface meteoroid cumulative-flux model and the comparable near-earth model is discussed in the light of theoretical predictions. It is shown that the effect of the gravitational field of the earth on the near-earth environment was greater than previously predicted. The implication is that the average meteoroid velocity relative to the earth is probably 17 km/s. The many low velocity impacts on the Surveyor 3 camera and tube are shown to be of lunar surface origin and to be primarily the result of rocket exhaust interaction.

Cour-Palais, B. G.↗