LCROSS will Impact the Moon Tomorrow
On October 9, 2009 at 13:31 CEDT (11:31 GMT) the upper stage of the Atlas rocket used to launch the NASA lunar probe LCROSS will crash into crater Cabeus near the Moon's South Pole. Four minutes later, around 13:35 CEDT (11:35 GMT), the spacecraft proper will follow.
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LCROSS (Lunar Crater Observation and Sensing Satellite) was launched together with LRO (Lunar Reconnaissance Orbiter) on 18 June 2009. While LRO has been inserted into a low polar orbit around the Moon, LCROSS still is orbiting the Earth on a highly eccentric trajectory.
The probe's first encounter with the moon, days after launch, was used to perform a targeted swingby that strongly increased the inclination of the orbit. LCROSS still regularly crosses the lunar orbit. Thanks to the high inclination, an impact in the polar regions becomes possible at such an encounter.
When LCROSS was launched, the presence of water ice was suspected, if at all, at the bottom of deep craters near the lunar poles. These locations are cloaked in eternal darkness and therefore always remain extremely cold. Some of this water is hoped to be dislodged by the impact blasts. Its chemical signature, as well as that of other soil constituents, is to be detected by the approaching probe and Earth-based telescopes.
We now know that significant amounts of water are present on the lunar surface, and not just at the poles. However, the LCROSS experiment still is important. Confirming or disproving the presence of abundant water ice in points of eternal darkness will confirm or disprove theories on how water is transported on atmosphere-less rocky bodies.
Though we know that there is abundant water on the moon (albeit apparently in low concentrations and distributed over wide areas) we do not know how the water got there or whether it can accumulate in given places. Knowing this would be of immense scientific and also practical interest.
As of tomorrow, we will know more on this, and of course, as the analysis of the obtained data continues, more and more information will be gleaned.
LCROSS will have to transmit its data in real time because there will be no chance for a re-transmit. News of the unfolding drama will be shown on NASA-TV.
I'm very much looking forward to this. There have been some impacts of lunar probes lately. The most recent one was that of the Japanese orbiter SELENE/Kaguya. But the LCROSS crash will pack more punch than that of preceding impacts, and what's more, it will be a double whammy!
Further Information
LCROSS Mission Web Site on nasa.gov
LCROSS Project Web Site of NASA's Ames-Research-Centre (ARC)
Press Release of NASA/ARC on the final selection of the target crater (Cabeus rather than Cabeus A)
"Where and How to Observe the LCROSS Impact": NASA web site listing events and observation opportunities related to the LCROSS impact
Launch Press Kit for LRO and LCROSS
Related Articles:
- The Low Down on Methane on Mars
- Close Asteroid Encounter Tomorrow
- How to Orbit a Lagrangian Point
- Tomorrow: Japanese Asteroid Probe Hayabusa Limps Home
- Tunguska 101
The press conference at NASA HQ on the day of the impact at 16:00 CEDT (2.5 hours after the event) was distinctly underwhelming, unless you are interested in hearing how tremendous and awesome everyone found each other.
However, the mission was a success, albeit not a visually spectacular one, and the rest is data evaluation, which is notoriously lengthy and time consuming.
Stay tuned!
Here is some preliminary information on well-informed Emily Lakdawalla's Planetary Society blog:
http://www.planetary.org/blog/article/00002161/
http://www.planetary.org/blog/article/00002160/
http://www.planetary.org/blog/article/00002159/