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Experiment Title: Study of Meteoroid Impact Craters on Various Materials

Original Principal Investigator(s): Mandeville, Dr. Jean-Claude - Invest. Role: Original, Mandeville, Dr. Jean-Claude - Invest. Role: Present, Mandeville, Dr. Jean-Claude - Invest. Role: Present, Mandeville, Dr. Jean-Claude - Invest. Role: Original,

Interplanetary space contains solid objects whose size distribution continuously covers the interval from submicron-sized particles to km-sized asteroids or comets. Some meteoroids originate from comets (mainly dust ejected at perihelion), some originate from collisions within the asteroid belt. A majority of particles are likely to come from comets but data from the Infrared Astronomy Satellite (IRAS) indicates that asteroids could be a source larger than expected. In addition to natural particles, a significant and growing number of particles has been added by human activity in near Earth space. In the vicinity of Earth, gravitational perturbations and the influence of the atmosphere greatly affect the distribution of the particles. Present knowledge of the occurrence and physical properties is based primarily on Earthbound observation of meteors, comets, zodiacal light, data from infrared satellites (IRAS) as well as on board measured flux by instrumented spacecraft (Pegasus, Vega, Giotto, Space Shuttle and the MIR Soviet Space Station ), study of lunar samples and dust collection in the upper atmosphere.

The spatial density (number per unit volume) of meteoroids varies as a function of distance from the sun, distance from a planet, ecliptic latitude and longitude. The lifetime of interplanetary dust is dynamically limited, gravitational and solar radiation pressure (Poynting Roberston effect) gradually reducing the size of the orbit after typically 10,000 years; the lifetime of particles is also controlled by collision processes. Submicron particles will be blown out of the planetary system by solar radiation pressure (beta meteoroids). In the vicinity of Earth, gravitational perturbations and the influence of the atmosphere greatly affect the distribution of the particles. In-situ detection and collection of dust by experiments flown on LDEF are expected to improve our current understanding of this aspect of the space environment.

Interplanetary dust particles (micrometeoroids) were expected to form well-defined craters upon impacting exposed material in space. Studying the frequency and features of these craters will provide data on the mass-flux distribution of micrometeoroids and, to a lesser extent, on the velocity, magnitude and direction. Limited crater studies have been done in the past with materials retrieved after exposure in space on Surveyor 3, Apollo 4 and 11, Gemini 10 and 11, and Skylab. However, little had been learned regarding the composition of impacting particles. This experiment focused on the determination of the composition of meteoroid material residues inside craters.

The determination of the chemical composition of the impacting particles is a critical issue. In general they are physically destroyed and mixed with target material in the process of crater formation. Even though little or no pristine material may be left for chemical analysis, particularly in metals such as tungsten or gold, it is possible to collect quite sufficient projectile residue material for analysis. Based on laboratory experiments, such residues may be reduced to a probable initial composition.

Photograph Classification: None

Associated Photograph(s):
LaRC - None
KSC - None
JSC - None

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