The Thermal Dissipation of Meteorites by Bumper Screens

Abstract

The method, proposed by Whipple, of protecting an interplanetary vehicle or artificial satellite from the effects of colliding meteorites by using a bumper screen, is investigated theoretically. It is assumed that when a meteorite hits a bumper screen, the whole of its kinetic energy is transformed into heat. This heat, which is generated at the point of collision, is considered to spread through a hemispherical volume of the screen, and if the resultant temperature rise is sufficient to melt the metal of the screen, it is said to have been thermally penetrated. The thicknesses of screens which will just be penetrated by various sizes of meteorites with a range of collision velocities are calculated. Results are given for both iron and stone meteorites, and general penetration equations derived which can be applied to screens of various metals. It is concluded that a bumper screen which would be practicable from the weight point of view would give reasonable protection, in fact a dural screen of thickness 0.1 cm would provide protection for meteorites up to about the 10th magnitude.