1. Radio meteor rates for a calculated mass range 10−6 gm to 10−4 gm have been recorded semi-continuously at Havana, Ill., since July 1965. Automatic equipment samples the rate at four different levels of sensitivity each half hour. A flux vs. mass power law has been derived from these data for each of a number of different weeks of observation. Between September 1965 and December 1966 the mean cumulative influx I of meteors/m2/sec/2π ster can best be described by the equation: where m is the lower mass limit in grams.

2. A micrometeoroid detection system, which hopefully was to have measured particle velocities and directions of arrival for masses greater than 10−12 gm, has been flown on the OGO-II satellite. A comprehensive in-flight calibration system has confirmed the correct operation of the experiment for more than one year in space. 700 hours of data have been analyzed and no micrometeoroid events have been observed. This excludes several hundred spurious events from the microphone sensors. The effective detection area of the instrument is 0·8 cm2 ster. Thus, to a probability of 0·86, the average flux of particles of mass greater than 10−12 gm must be less than 6 × 10−2 particles/m2/sec/2π ster.