Lunar Ejecta and Meteorites

Description

The Apollo 17 lunar ejecta and meteorite experiment measured the frequency with which the moon was impacted by primary cosmic dust particles and the effect of the lunar ejecta emanating from the sites of meteorite impacts on the lunar surface. The experiment had the following specific objectives -- (1) to determine the background and long-term variations of cosmic dust influx rates in cislunar space, (2) to determine the extent and nature of lunar ejecta produced by meteorite impacts on the lunar surface, (3) to determine the relative contribution of comets and asteroids to the earth's meteoroid ensemble, (4) to study possible correlations between the associated ejecta events and the times of the earth's crossing of cometary orbital planes and meteor streams, (5) to determine the extent of the contribution of interstellar particles toward the maintenance of the zodiacal cloud as the solar system passes through galactic space, and (6) to investigate the existence of an effect called 'earth focusing of dust particles.' The equipment for this experiment, which was part of the Apollo 17 ALSEP, included one deployable unit with detector plates, ALSEP central station electronics, and the cable and astromate connector for mating the external unit with the central station. The external unit components or sensors consisted of suppressor and collector plates, impact plates, film frames, and microphones. The sensor had a field of view of plus or minus 60 deg and an angular resolution of plus or minus 26 deg. It measured particle impacts in an energy range of 1 to 1000 ergs with a primary frequency of measurement of 1.E-4 impacts/sq m/s. The external unit was erected and deployed on the lunar surface about 8 m south of the ALSEP central station. The unit was aligned to plus or minus 5 deg of the scan-shadow line and leveled to plus or minus 5 deg. A cover provided to shield the detector plates from dirt particles produced during lunar module ascent liftoff was jettisoned by earth command at a suitable time after liftoff.