Bad Astronomy

Image of future LCROSS lunar impact site

The spot where NASA’s LCROSS spacecraft will impact the Moon on October 9 has been released by astronomers with the European Space Agency:

The impact site is the crater Cabeus-A, the largish crater to the left of center. The resolution of the image is about 50 meters/pixel, and the field of view is about 50 km (30 miles) across. The crater is near the Moon’s south pole, and the bottom is permanently in shadow. See the shadow across the crater? As the Moon spins and orbits the Earth, that shadow never lifts, but instead moves around the crater floor like the hand of a celestial clock.

We know there is water all over the Moon in small quantities, but is there a lake of frozen water under the crater’s dusty floor? When LCROSS impacts, we may find out.

This image was taken by SMART-1, an ambitious ESA spacecraft that orbited the Moon for nearly two years. Its ultimate fate? It too impacted the lunar surface in September 2006. While that impact wasn’t meant to hunt for water, it did kick up some dust, and made a flash bright enough to be detected from Earth. Its mission was a big success, and its demise was a harbinger for things to come on October 9.

Image credit: B.Grieger, B.H. Foing & ESA/SMART-1/ AMIE team