Window Meteoroid Detector

Description

The objective of this experiment was to use the Apollo 12 command module heat shield window surfaces (fused silica) to obtain information about the flux of meteoroids with masses of 1 nanogram or less. About 0.4 sq m of the window surfaces were used as meteoroid impact detectors. In addition, the residue and the morphology of the craters produced by these meteoroids were examined to obtain information concerning the dynamic and physical properties of the meteoroids. If the assumption were made that the velocity distribution of the smaller meteoroids was the same as that of much larger meteoroids, then this experiment could provide data on the mass density of the meteoroids. The composition of the meteoroid residue in the crater or in the fused glass was determined by use of a scanning electron microscope nondipersive X-ray detector. The window surface was an ideal detector because the surface spallation area was 25 to 100 times larger than the diam of the impacting meteoroid. Thus, a 0.5- to 2-micron meteoroid would make a 50-micron crater, which could be detected by a 20x optical scan with a stereozoom microscope. Similar experiments were flown on previous Apollo flights.