By sending the laser pulses to the surface lots of times, the Clementine science team could produce a map of elevations for the entire Moon. It shows the extent of the South Pole-Aitken basin and shows that the basin is quite deep, at least 12 km deeper than its surroundings. P lanetary scientists love deep holes, especially those made by huge impacts. We want to know how they form, how the energy of a high-speed projectile is converted to explosive excavation of crushed and melted rock, how much of the target is melted, and how deep the rocks now on the surface came from. A hole the size of SPA is especially exciting as it might have dug well into the mantle of the Moon.
Mantles are important.
They are deeper and compositionally different from the crust which forms the surface of a planet. Mantles contain information about a planet's total composition, a key parameter in understanding planet formation and how the planets vary in composition with distance from the Sun. The data have been converted into information about the iron and titanium concentrations of the floor of SPA basin. Paul Lucey and his colleagues produced the maps. The basin contains more FeO and TiO 2 than typical of the lunar highlands.