Nasa spacecraft orbits moon on New Year's Eve as part of $500m mission to scan Earth¿s nearest neighbour from crust to core | Mail Online

New Year's Mission: One of the two twin Grail probes entered orbit on New Year's Eve

Grail is expected to help researchers better understand why the moon is asymmetrical and how it formed by mapping the uneven lunar gravity field. The mission will cost nearly $500million. Previous lunar missions have attempted to study the moon's gravity -which is about one-sixth Earth's pull - with mixed results. Grail is the first mission devoted to this goal.
http://www.dailymail.co.uk/news/article-2080881/Nasa-spacecraft-orbits-moon-New-Years-Eve-500m-mission-scan-Earth-s-nearest-neighbour-crust-core.html