Published online by Cambridge University Press: 14 August 2015
18 years have elapsed since the first data on meteoritic dust were obtained by means of the instruments installed on a rocket under the guidance of Professor Bohn. Since then these investigations, by means of different instrumentation, have been carried on in the vicinity of the Earth and in interplanetary space. By now rocket and satellite data have been obtained on the spatial density of meteoritic particles with masses of 10−7–10−16 grams and on their energy; a concept of the mass spectrum of these particles has been obtained as well as the first data on their velocities. Over recent years very difficult experiments have been initiated for obtaining samples of meteoritic particles directly from high altitudes with a view to determining their physical properties, chemical composition, and the destroying effect.