LCROSS crashed into the Moon last month, although the lack of a visible plume in the real-time video feed made the impact less exciting than it could have been. But the lack of a visible plume is hardly a failure, since LCROSS was sent to do science, not make a flashy impact.
And it looks like LCROSS has managed to find exactly what it was sent to find on the Moon. Analysis of the near-infrared and ultraviolet spectra as LCROSS passed through the plume kicked up by the impact of the Centaur rocket upper stage indicates that the plume contained water. And not the piddling amount of water that seems ubiquitously present on the rest of the Moon: there must be significant reservoirs of water at Cabeus crater. Just how much water there might be remains to be seen, as well as the identity of other compounds that appear to have been detected in the impact plume.
LCROSS has just crashed into Cabeus crater on the Moon four minutes after the Centaur upper stage crashed, too. During the four minutes, LCROSS observed the plume that the upper stage kicked up and hopefully getting data that confirms the existence of water. The spacecraft had separated from the Centaur upper stage almost ten hours previously, after which they traveled almost 10,000 kilometers before reaching the Moon. NASA TV had just broadcast the impact live, and it's impressive how much media attention the LCROSS impact has grabbed. I had thought only space enthusiasts such as myself would have paid any attention to it.
LCROSS was going to crash into crater Cabeus A. But after analyzing data from spacecraft such as the LRO, the Lunar Prospector, Chandrayaan-1, and Kaguya, the impact site for LCROSS has been changed to Cabeus (proper), a bigger crater close to Cabeus A. This determination was made because the hydrogen content and terrain suggests that crashing into Cabeus rather than into its satellite crater would give the best chance of observing water in the resulting plume.
LCROSS, the Lunar Crater Observation and Sensing Satellite launched in June, will be crashing into the Moon next month. And now we know exactly where it will crash into the Moon. The upper rocket stage that launched LCROSS will be crashing into the permanently shadowed parts of the crater Cabeus A near the Moon's south pole, which will kick up a huge plume that LCROSS will observe. And it will be soon followed by the crash of LCROSS itself, which will kick up a smaller plume that telescopes on Earth could observe.
With any luck, there will be water in the permanent shadows around the Moon's south pole, and LCROSS will be able to definitely confirm its presence.
However, LCROSS will not crash into the Moon after the four days: instead, it will use the Moon as a gravitational assist to enter a very large orbit around the Earth. This is so that the impact can occur at a high angle rather than the shallow angle that it would crash with if it were to impact the Moon directly. Of course, LCROSS won't be crashing into the Moon by itself: it will first observe a much larger impact at the lunar south pole caused by the upper stage of the rocket that launched LRO and LCROSS, which will soon be followed by a much smaller impact from LCROSS itself. The impact will occur sometime in October, and with any luck, we might get definite confirmation of water deposits on the Moon.
Random musings in a variety of subjects, from science to religion.