National Aeronautics and Space Administration + NASA Quest
+ Search Quest
 Find it at NASA
 Home mission About the Moon impact
 LCROSS - Lunar CRater Observation and Sensing Spacecraft
 Tech Info observation education news


Lunar CRater Observation and Sensing Satellite (LCROSS)


The Lunar CRater Observation and Sensing Spacecraft (LCROSS) traveled to the Moon as a co-manifested payload aboard the launch vehicle for the Lunar Reconnaissance Orbiter (LRO). The Mission Objectives of the LCROSS were to advance the Vision for Space Exploration (VSE) by confirming the presence or absence of water ice in permanently shadowed craters at the Moon’s Polar regions. LCROSS also provided technologies and modular, reconfigurable subsystems that can be used to support future mission architectures.

The LCROSS mission delivered a 2000 kg impactor, to a lunar crater with a 10 km footprint accuracy, creating a 1000 metric ton plume of lunar ejecta—more than 200 times the energy of Lunar Prospector (LP). This ejecta plume was visible from a number of Lunar-orbital and Earth-based assets. Water signatures have been measured with an in-situ Shepherding Spacecraft that followed the Centaur upper stage to the lunar surface. Designed to sense sub-surface regolith water concentrations to < 0.5%, LCROSS could leverage observations from Earth-based platforms and other lunar orbiting assets, such as LRO, Chandra, and the Hubble Space Telescope. Once observations were made by the Shepherding Spacecraft, it became a 700 kg impactor as well.

LCROSS used the LRO launch vehicle’s spent Centaur upper stage as a kinetic impactor. The Centaur was maneuvered by a small “adapter” Shepherding Spacecraft (S-S/C) between the Centaur and LRO payload. After the LRO separated to head off to the moon for its own mission, the S-S/C guided the Centaur into a lunar impact trajectory, separated from the Centaur about 7 hours before impact, and followed the Centaur about 10 minutes behind. After Centaur impact, the S-S/C flew through the Centaur impact plume, while telemetering high resolution spatial and temporal measurements of the impact, plume and fresh Centaur crater. A campaign of ground-based observations was conducted to support and complement the S-S/C observations. The S-S/C itself became an impactor, impacting the Moon several km from the Centaur impact, observed from Earth to provide important information about possible non-uniformity of hydrogen trapped in the shadowed craters.

The S-S/C approach to the mission leveraged an existing high value asset, the Centaur, efficiently using existing space systems to obtain a high confidence measurement of lunar polar water ice concentration. The Lunar Gravity Assist, Lunar Return Orbit (LGALRO) 86 day orbit provided the necessary time to track, control and achieve a precision impact, while also achieving a high impact velocity and angle of incidence. The high incident impact provides an ideal plume to be observed by the S-S/C and ground and space-based instruments.

NASA's Ames Research Center oversaw the development of the LCROSS mission with its spacecraft development and integration partner, Northrop Grumman.

Technical Information
Overview | Mission Rationale | Spacecraft and System Description | Instrumentation | Water Detection | Targeting

Visit the NASA Mission Site @

 FirstGov  NASA

Editor: Brian Day
NASA Official: Daniel Andrews
Last Updated: October 2010