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  • 11
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    Impact of Saturn ring particles on Pioneer 11 (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: The detection of particles near the rings of Saturn by the meteoroid detection instrument on board Pioneer 11 is discussed. The instrument consists of 234 penetration detectors, distributed between two independent data channels each of which is designed to become inhibited for a period of 77 min after the registration of a penetration event in that channel. At least four particles penetrated the detectors in the 4.5 h period around Saturn periapsis at radial distances between 1.36 and 3.1 Saturn radii, a radial distribution inconsistent with the gravitational focusing of meteoroids. The detection of particles which may have been part of the E ring before the crossing of the ring plane suggests that this ring may be 1800 km thick, with an optical thickness greater than 10 to the -8th.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Science; 207; Jan. 25
    Format: text
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    NASA TECHNICAL REPORTS
  • 12
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    Results of Pioneer 10 and 11 meteoroid experiments - Interplanetary and near-Saturn (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: The meteoroid penetration detectors on Pioneer 10 (channel 0) recorded 95 penetrations through the 25-micron stainless steel test material while the spacecraft was between 1 and 18 AU. The spatial density of 10 to the -9 g meteoroids is found to be essentially constant between 1 and 18 AU. The meteoroid penetration detectors on Pioneer 11 recorded 87 penetrations (55 on channel 0 and 32 on channel 1) through the 50-micron stainless steel test material while the spacecraft was between 1 and 9 AU. It is found that the meteoroids between 4 and 5 AU are not in direct circular or near-circular orbits near the ecliptic plane. The Pioneer 11 data obtained between 4 and 5 AU are best explained by the meteoroids being in randomly inclined orbits of high eccentricity. If meteoroids are in these cometlike orbits, the great increase in penetration flux previously measured near Jupiter with the Pioneer 10 experiment cannot be attributed to gravitational focusing unless the size distribution of meteoroids changes substantially between 1 and 5 AU. At Saturn encounter, the penetration flux increased by about three orders of magnitude, probably as the result of impacts from ring particles. Saturn's ring E is estimated to be 1800 km thick with an optical thickness greater than 10 to the -8.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research; 85; Nov. 1
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    NASA TECHNICAL REPORTS
  • 13
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    Hypervelocity impact tests on Space Shuttle Orbiter RCC thermal protection material (1978)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: It is noted that the Shuttle Orbiter will be more subject to meteoroid impact than previous spacecraft, due to its greater surface area and longer cumulative time in space. The Orbiter structural material, RCC, a reinforced carbon-carbon laminate with a diffused silicon carbide coating, is evaluated in terms of its resistance to hypervelocity impact. It was found that the specimens (disks with a mass of 34 g and a thickness of 5.0 mm) were cratered only on the front surface when the impact energy was 3 J or less. At 3 J, a trace of the black carbon interior was exposed. The specimens were completely penetrated when the energy was 34 J or greater.
    Keywords: COMPOSITE MATERIALS
    Type: Journal of Spacecraft and Rockets; 15; July-Aug
    Format: text
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    NASA TECHNICAL REPORTS
  • 14
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    Diode laser satellite systems for beamed power transmission (1990)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A power system composed of an orbiting laser satellite and a surface-based receiver/converter is described. Power is transmitted from the satellite to the receiver/converter by laser beam. The satellite components are: (1) solar collector; (2) blackbody; (3) photovoltaic cells; (4) heat radiators; (5) laser system; and (6) transmission optics. The receiver/converter components are: receiver dish; lenticular lens; photocells; and heat radiator. Although the system can be adapted to missions at many locations in the solar system, only two are examined here: powering a lunar habitat; and powering a lunar rover. Power system components are described and their masses, dimensions, operating powers, and temperatures, are estimated using known or feasible component capabilities. The critical technologies involved are discussed and other potential missions are mentioned.
    Keywords: LASERS AND MASERS
    Type: NASA-TP-2992 , L-16669 , NAS 1.60:2992
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 15
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    Influence on the bumper and main wall material on the effectiveness of single meteoroid bumpers (1965)
    In:  CASI
    Details
    Publication Date: 2019-05-29
    Description: Relative effectiveness of several bumper and main wall materials in reducing impact damage of spherical aluminum projectiles
    Keywords: STRUCTURAL MECHANICS
    Type: NASA-TN-D-3104
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 16
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    Solar-pumped photodissociation iodine laser (1986)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: The scientific feasibility of a solar-pumped iodine photodissociation laser for space applications is under investigation. Recently, a 2-W CW output for more than one hour was achieved using n-C3F7I vapor as the laser material and a vortex-stabilized argon arc as the light source.
    Keywords: LASERS AND MASERS
    Type: ; : Conference on the
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  • 17
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    Threshold kinetics of a solar-simulator-pumped iodine laser (1984)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A model of the chemical kinetics of the n-C3F7I solar-simulator-pumped iodine laser is utilized to study the major kinetic processes associated with the threshold behavior of this experimental system. Excited-state diffusion to the cell wall is the dominant limiting factor below 5 torr. Excited-state diffusion to the cell wall is the dominant limiting factor below 5 torr. Excited-state recombination with the alkyl radical and quenching by the parent gas control threshold at higher pressures. Treatment of the hyperfine splitting and uncertainty in the pressure broadening are important factors in fixing the threshold level. In spite of scatter in the experimental data caused by instabilities in the simulator high-pressure high-pressure arc, reasonable agreement is achieved between the model and experiment. Model parameters arrived at are within the uncertainty range of values found in the literature.
    Keywords: LASERS AND MASERS
    Type: NASA-TP-2241 , L-15684 , NAS 1.60:2241
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 18
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    Meteoroid bumper experiment on Explorer 46 (1981)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The effectiveness of a meteoroid bumper in reducing meteoroid penetrations is discussed. The bumper reduced the penetration flux by a factor of 30 and demonstrated a weight savings of a factor of 6.9 in the material needed to resist meteoroid penetration. The method of calculating the penetration flux recommended in the NASA space vehicle design criteria for meteoroid damage assessment was found to be very conservative, and changes are suggested. The optimum distribution of material between a bumper and the main wall is discussed.
    Keywords: SPACECRAFT DESIGN, TESTING AND PERFORMANCE
    Type: AD-A277032 , NASA-TP-1879 , L-14329
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 19
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    Threshold kinetic processes for t-C4F9I (1985)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: To determine the relative threshold of the lasant gas t-C4F9I in comparison to n-C3F7I, the pump energy to reach threshold for photodissociation iodine lasing is measured in a common aparatus. The comparison is made for the threshold energies in the iodide pressure range up to 50 Torr when 64-J electric input into a flashlamp is used for pumping. It is shown from the results that qualitative differences between the thresholds of the two gases result from the degree to which steady state is achieved by the time threshold is reached. The estimated recombination rate for t-C4F9I is found to be much larger than the value given by Ershov et al (1978).
    Keywords: LASERS AND MASERS
    Type: Optics Communications (ISSN 0030-4018); 53; 367-370
    Format: text
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    NASA TECHNICAL REPORTS
  • 20
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    Meteoroid impacts on Mars and the secondary particle environment (1972)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The degree to which the thin Martian atmosphere filters out meteoroids approaching the Martian surface was calculated by using a model of the meteoroid environment, a model of the Martian atmosphere, and equations of meteor physics. The secondary particle environment on the surface of Mars caused by the material ejected from meteoroid craters was modeled. The model consists of the mass distribution and the speed distribution of the secondary particles. Calculations were made of the penetration flux for aluminum structures on the Martian surface. The penetration hazard on the Martian surface was compared with the penetration hazard in space near Mars and on the lunar surface.
    Keywords: SPACE SCIENCES
    Type: NASA-TN-D-6951 , L-8479
    Format: application/pdf
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