By Peter Weiss
Earth-orbiting space junk zips along so fast that even small pieces striking the International Space Station and other satellites could cause serious damage. Based on laboratory experiments, a Japanese team now reports that these hypervelocity impacts emit microwaves. The finding suggests a new way to remotely detect space-junk hits, say engineers who study such impacts.
Researchers have long known that hypervelocity impacts give off bursts of heat and visible light. Those occur because the kinetic energies of the colliding objects convert rapidly to heat, setting aglow the materials involved.