Meteoroid experiments by five Lunar Orbiters have provided a direct measurement in the near-lunar environment of the rate of meteoroid penetration of 0.025-mm-thick beryllium-copper. Each experiment used 20 pressurized-cell detectors having a total effective exposed area of 0.186 m2. The spacecraft carrying the cells were in both equatorial and polar orbits; altituded ranged between 30 and 6200 km. Data collected continuously for 17 months indicate that the rate of penetration in the lunar environment is approximately half the rate in the near-earth environment as measured by detectors of the same type aboard Explorers XVI and XXIII.

The only work to date to collect data gathered during the American and Soviet missions in an accessible and complete reference of current scientific and technical information about the Moon.

The twenty-two papers contained in this volume have been selected from the Proceedings of the 2nd COSPAR Colloquium. The exploration of planet Mars will be the focal point of the planetary missions in the coming years, so the investigation of the surface and the upper layers of the soil is of primary importance. The major space agencies are actively working to understand the environmental and technical requirements of the planned missions and experiments and it is predicted that the planet will be host to both ground based and atmospheric investigations in the near future.

A mathematical model is used to represent 8pik's 1958 physical theory of meteors in a form convenient for programming the computation of meteoroid photometric mass values. Sub-samples of 333 photographic meteors from McCrosky and Posen's sample are selected with respect to magnitude scaled for minimum velocity. A statistical comparison between the 1958 8pik resulst and the 1933 8pik provisional result, the Harvard-Meteor project basis for mass values, lative flux in absolute units for mass, momentum and energy are given separately for the terrestrial influx and for the lunar and interplanetary vehicle onfluxes.

Penetration flux calculation for multiwall structure on Lunar Orbiter spacecraft missions.