LCROSS: A "morning after" wrapup
Posted by Emily Lakdawalla
09-10-2009 12:17 CDT
So the big drama on LCROSS is over. There's every indication that the mission was successful: the Centaur spacecraft crashed where it was directed to, and the LCROSS shepherd spacecraft captured what appears to be a beautiful mutlivariate data set on the crash and its post-impact flash, and its spectrometers gathered data pointing in the correct direction for gathering the right kind of data that they need to determine whether or not there was water in the spot where the Centaur crashed. At the same time, numerous ground-based observatories had excellent weather for observation and gathered both visible and infrared data.
An early report from Lunar Reconnaissance Orbiter indicates that at least two of its instruments, the LAMP ultraviolet spectrometer and the Diviner radiometer, have successfully detected the ejecta plume and the impact crater, respectively. There were numerous other spacecraft watching, including Hubble, so I'm sure there is more wonderful data yet to come.
So congratulations to the LCROSS team on a job well done, on a low budget! It will be fun to see the science results trickle out over the coming days and weeks. Project Scientist Tony Colaprete indicated that they planned to have some results to present to the scientific community in time for the December American Geophysical Union meeting.
However, the night was also disappointing, because no matter how big a telescope you used to look at the Moon last night, you didn't see an impact flash. Considering that the mission thought you might be able to see it in scopes as small as 30 centimeters, it's really surprising. Scientists will definitely learn something very interesting from the lack of a visible plume -- it's always interesting and thought-provoking when expectations are not met. But even though it's interesting, it's still very disappointing; there were thousands of people tuned in all over the world to watch for that flash, and there was no flash to see. It would not be wrong to turn to those people and say, "sorry to disappoint you -- we really didn't expect what we saw (or rather, what we didn't see) last night. We hope that despite the disappointment, you'll tune in again next time there's a dramatic event in space to follow in real time."
I think maybe we were watching for the wrong thing. How exciting and thrilling it was to see the Moon looming in LCROSS' forward view! At first it didn't fill the frame, but quickly it grew to spread out across the field of view of LCROSS' camera, growing very slowly at first, then faster and faster until suddenly there was a white screen, indicating no more transmission from that camera. It was as exciting as the Deep Impact crash sequence shot by the impactor spacecraft, only it had much better resolution. In hindsight, I think that the drama of those approach images should have been hyped more; we didn't get a flash, but we got to ride along to the crash, all the way down to the surface of the Moon.
It's tempting to stay glued to my computer to wait for some more stuff to trickle out. But I only got four hours' sleep last night, and I think I'd better go get a little bit more. So I'm going to sign off for a few hours, and come back later to see what's appeared while I've been gone.