LCROSS Gets New Impact Site

Officials at the American space agency NASA announced yesterday that they had switched the target crater for the Lunar CRater Observation and Sensing Satellite (LCROSS) spacecraft, from Cabeus A to the larger, nearby Cabeus. Upon closer reviews of the proposed crash site, in photos provided by a number of lunar missions including Europe's SMART-1, mission planners decided that the larger Cabeus had a higher chance of holding water-ice. Additionally, it was reported that the new target crater had the largest hydrogen concentration on the Moon's South Pole, Space informs.

The impacts are now scheduled to take place on October 9. First, the spent Centaurus rocket stage that LCROSS has been carrying around since launch will be dropped into the crater. Telescopes, both in orbit and on the ground, as well as anything with a camera that can reach that far will image the impact site. Shortly after, the spacecraft will be purposefully crashed at the same location itself. Experts are looking to create a large-enough plume of dust after the impact, so that spectrometers can positively identify the existence of water-ice in the region.

“The general consensus of lunar experts led by the LCROSS science team is that Cabeus shows, with the greatest level of certainty, the highest hydrogen concentrations at the south pole. Further consideration of the most current terrain models provided by JAXA's Kaguya spacecraft and the LRO Lunar Orbiter Laser Altimeter (LOLA) was important in the decision process,” NASA said in a statement.

“The models show a small valley in an otherwise tall Cabeus perimeter ridge, which will allow for sunlight to illuminate the ejecta cloud on October 9, and much sooner than previously estimated for Cabeus. While the ejecta does have to fly to higher elevations to be observed by Earth assets, a shadow cast by a large hill along the Cabeus ridge, provides an excellent, high-contrast, back drop for ejecta and vapor measurements,” the press release continued.

Over the next week and a half, the team will focus on finding the best possible location within Cabeus to slam LCROSS and its Centaurus rocket stage in. They need to avoid hard spots, where the two impactors could be lost for nothing, but also to select a position where sunlight will fall directly on the ejection plume, and evidence its composition.