Observations of the lunar impact plume from the LCROSS event

Abstract

We observed emission from sodium (Na) ejected from the Lunar Crater Observing and Sensing Satellite (LCROSS) impact into Cabeus Crater on October 9, 2009, using the McMath-Pierce telescope. In our 88 km 2 field of view, we saw on the order of 2 g of Na in the first 9 minutes after the LCROSS impact. A comparison of our observed Na above the limb with simulations that assume a gas temperature of 1000 K indicates that 0.5 - 2.6 (1.5±1) kg of Na were released during the LCROSS impact. Lower temperatures would result in a lower total sodium release. The model of an isotropic expanding cloud best reproduces the observations. © 2010 by the American Geophysical Union.