Direct Measurement of Interplanetary Dust Particles in the Vicinity of Earth

ADDITIONAL knowledge about interplanetary dust particles has been obtained from the direct measurements made with rockets, satellites, and space probes. The results obtained with the microphone type of dust particle sensor carried by the U.S. satellites, Explorer I (1958 Alpha) and Vanguard III (1959 Eta); the U.S. space probe, Pioneer I; and the Soviet vehicles, Sputnik III (1958 Delta 2), Space Rockets I and II, and the Interplanetary Station (1959 Theta), have already been reported. In addition, a definitive set of data has recently been obtained with the U.S. satellite, Explorer VIII (1960 Xi). A series of corrections has been completed which allows our results from a series of seven successful high-altitude rockets instrumented at Oklahoma State University to be used in quantitative discussions of interplanetary dust particles. We would like to present the preliminary results (including a new and very interesting curve for the mass distribution and spatial density) from an analysis of the available direct measurements of interplanetary dust particles.