LCROSS was designed to collect and relay data from the impact and debris plume resulting from the launch vehicle's spent Centaur upper stage (and data-collecting Shepherding Spacecraft) striking the crater Cabeus near the south pole of the Moon.

[6] LCROSS launched with the LRO aboard an Atlas V rocket from Cape Canaveral, Florida, on June 18, 2009, at 21:32 UTC (17:32 EDT).

"[8] Lunar impacts, after approximately three orbits, occurred on October 9, 2009, with the Centaur crashing into the Moon at 11:31 UTC and the Shepherding Spacecraft following a few minutes later.

[16] The Centaur upper stage acted as a heavy impactor to create a debris plume that rose above the lunar surface.

[1] It was hoped that spectral analysis of the resulting impact plume would help to confirm preliminary findings by the Clementine and Lunar Prospector missions which hinted that there may be water ice in the permanently shadowed regions.

Mission scientists expected that the Centaur impact plume would be visible through amateur-class telescopes with apertures as small as 25 to 30 cm (10 to 12 inches).

[5] The LCROSS mission took advantage of the structural capabilities of the Evolved Expendable Launch Vehicle (EELV) Secondary Payload Adapter (ESPA) ring[19] used to attach LRO to the Centaur upper-stage rocket to form the Shepherding Spacecraft.

The mission's strict schedule, mass, and budget constraints posed difficult challenges to engineering teams from NASA Ames Research Center (ARC) and Northrop Grumman.

[22] After assembly and testing at Ames, the instrument payload, provided by Ecliptic Enterprises Corporation,[23] was shipped to Northrop Grumman on January 14, 2008, for integration with the spacecraft.

A data handling unit (DHU) collected the information from each instrument for transmission back to LCROSS Mission Control.

[citation needed] Because of data bandwidth issues, the exposures were kept short, which made the plume difficult to see in the images in the visible spectra.

[25] On November 13, 2009, NASA reported that multiple lines of evidence show water was present in both the high-angle vapor plume and the ejecta curtain created by the LCROSS Centaur impact.

[5] Additional confirmation came from an emission in the ultraviolet spectrum that was attributed to hydroxyl fragments, a product from the break-up of water by sunlight.