4. Map fresh craters to assess the abundance of small impacts in the recent past.
Much like someone standing out in the sun for too long, the lunar surface darkens with time. Able to sense the different tones of the soil, M3 will enable scientists to identify craters formed during the past 1 billion years, and to calculate the approximate frequency with which the Earth-Moon system has been impacted during that period. Earth's oceans and turbulent landscape haven't preserved our planet's craters nearly as well as the comparatively unchanging Moon. Thus, lunar craters provide the best available record of our own recent impact history -- information that can give us some idea of the rate at which the surface of our own planet is struck by asteroids and comets.
