HYPERVELOCITY IMPACTS ON SOLAR ARRAYS : ANALYSIS OF SECONDARY PARTICLES EJECTION AND IMPLICATIONS FOR ENVIRONMENT

摘要

Analysis of impacts detected on the Hubble space telescope solar arrays provides us with a great deal of data on impact mechanism into thin, brittle and layered targets, such as solar cells. The bulk of ejected material produced by an impact on a brittle target is much more important than on a ductile metallic target, because of the formation of spall fragments in a conchoidal zone. The spall phenomenon is increased by the multilayered structure of solar cells : delaminations between the cover-glass and the silicon layer create large fragments ejected at low velocities. The high production rate of spall fragments is a preoccupying fact because they have long lifetimes in orbit and will increase the debris population in the long run. The smallest comminuted fragments are ejected at high velocity in a debris cone. These fragments are likely to produce secondary impacts on the components of complex and large space structures, such as space stations. Quantitative assessment of debris flux increase due to secondaries is proposed.