A Smashing End to LCROSS

NASA Spacecraft Impacts Lunar Crater in Search for Water Ice

LCROSS impact crater as seen with the visible light camera.
Credit: NASA

NASA’s Lunar Crater Observation and Sensing Satellite, or LCROSS, created twin impacts on the Moon’s surface early Friday in a search for water ice. Scientists will analyze data from the spacecraft’s instruments to assess whether water ice is present. Water ice could prove to be a valuable resource for future human explorers on the Moon’s surface.

The satellite traveled 5.6 million miles during a 113-day mission that ended in the Cabeus crater, a permanently shadowed region near the moon’s south pole. The spacecraft was launched June 18 as a companion mission to the Lunar Reconnaissance Orbiter from NASA’s Kennedy Space Center in Florida.

“The LCROSS science instruments worked exceedingly well and returned a wealth of data that will greatly improve our understanding of our closest celestial neighbor,” said Anthony Colaprete, LCROSS principal investigator and project scientist at NASA’s Ames Research Center in Moffett Field, Calif. “The team is excited to dive into data.”

In preparation for impact, LCROSS and its spent Centaur upper stage rocket separated about 54,000 miles above the surface of the Moon on Thursday at approximately 6:50 p.m. PDT.

Moving at a speed of more than 1.5 miles per second, the Centaur hit the lunar surface shortly after 4:31 a.m. PDT Oct. 9, creating an impact that instruments aboard LCROSS observed for approximately four minutes. LCROSS then impacted the surface at approximately 4:36 a.m. PDT.

NASA’s LCROSS mission.
Credit: NASA Ames

In addition to the nine LCROSS spacecraft instruments that gathered data, the Lunar Reconnaissance Orbiter now orbiting the Moon also observed the impact. The Hubble Space Telescope took observations of the spectra, and numerous ground-based telescopes all had their eyes on the Moon’s south pole at the time of impact. All this data will be shared with the LCROSS science team for analysis. The LCROSS team expects it will need several weeks of analysis before it can make a definitive assessment of the presence or absence of water ice.

Visual light images of the Moon did not show an observable plume of ejected material from the impact, but scientists will be studying the images more closely over the coming days and weeks. Infrared images did show a hot flash after impact, indicating that a crater was created. Scientists are especially interested in analyzing the spectral data of the impact, looking not only for evidence of water but for any other molecular signal as well. At a NASA press conference, scientists reported seeing evidence of sodium in the spectra, but they could not say what the sodium indicates other than something was "thermalized" at the point of impact.

The images and video collected by the amateur astronomer community and the public will be used to enhance our knowledge about the Moon.

"One of the early goals of the mission was to get as many people to look at the LCROSS impacts in as many ways possible, and we succeeded," said Jennifer Heldmann, Ames’ coordinator of the LCROSS observation campaign. "The amount of corroborated information that can be pulled out of this one event is fascinating."

"It has been an incredible journey since LCROSS was selected in April 2006," said Daniel Andrews, LCROSS project manager at Ames. "The LCROSS Project faced a very ambitious schedule and an uncommonly small budget for a mission of this size. LCROSS could be a model for how small robotic missions are executed. This is truly big science on a small budget."