LCROSS
LCROSS deliberately impacted a permanently shadowed region near the lunar south pole and observed the resulting debris plume.
The mission in three questions
- Was water actually present in material excavated from a permanently shadowed cold trap?
- Which other volatile species were stored with it?
- Could a controlled impact expose otherwise inaccessible polar material for remote analysis?
Mission purpose and context
LCROSS was designed around a controlled impact experiment: strike a permanently shadowed lunar region and analyse material thrown into sunlight. This approach provided a way to sample otherwise inaccessible cold-trapped material remotely.
Spacecraft and mission architecture
LCROSS travelled with LRO and used the spent Centaur upper stage as the primary impactor. A shepherding spacecraft followed the Centaur, observing the plume with spectrometers and cameras before it too impacted the Moon.
Payload and measurement highlights
- Visible and near-infrared spectrometers searched the impact plume for water and other species.
- Cameras documented plume evolution and impact conditions.
- Photometric and mid-infrared measurements supplied complementary information about ejecta and thermal emission.
How this mission collected evidence
| Instrument | Measurement | Scientific connection |
|---|---|---|
| Spectrometers LCROSS spectrometer suite | Composition of the impact plume | Direct detection of water and other volatile species excavated from Cabeus |
Browse the lunar mission instrument reference.
Flight and surface operations
On 9 October 2009 the Centaur struck Cabeus crater near the south pole. The following spacecraft observed the ejecta plume for several minutes, transmitted data to Earth and then impacted nearby.
Mission sequence
- 18 June 2009: launched together with LRO.
- 9 October: the spent Centaur stage impacted Cabeus crater in a permanently shadowed south-polar region.
- The shepherding spacecraft flew through and observed the ejecta plume before impacting minutes later.
Science and measurements
Spectroscopic analysis detected water in the excavated material along with other volatile species. The result supplied direct evidence that at least some permanently shadowed polar material contains water rather than merely a remote-sensing signature of hydrogen.
What changed because of this mission
LCROSS changed the evidence base for lunar polar water. It did not show that every shadowed crater contains easily extractable ice, but it demonstrated that volatile-rich material exists in a specific polar cold trap.
Mission outcome
The experiment detected water and other volatile materials in material excavated from Cabeus crater.
The outcome should be read against the mission's actual objectives and architecture. Multi-element missions can have different results for an orbiter, lander, rover or sample-return stage, while a shortened mission can still return important science or demonstrate a critical technology.
Continue through the ecosystem
Primary reference
NASA Science - LCROSS. LCROSS impact experiment and direct detection of water-bearing material in Cabeus.