Luminous efficiency measurements for silicon and aluminum simulated micrometeors

Laboratory measurements on simulated silicon and aluminum micrometeors in an air atmosphere have produced values for the elemental photographic luminous efficiencies of silicon over a velocity range 13-48 km/sec and of aluminum over a range 12-42 km/sec. The photographic luminous efficiency of both elements first increases with increasing velocity, then reaches a peak and declines. Supplementary measurements on Si and Al in atmospheres of O2 and N2 support the air results.