New Year at the Moon

Using a precision formation-flying technique, the twin GRAIL spacecraft will map the moon's gravity field, as depicted in this artist's rendering. Image credit: NASA/JPL-Caltech

The NASA GRAIL mission, which was launched last September, has arrived at the Moon. GRAIL-A arrived on New Years Eve, while GRAIL-B arrived a day later, in the new year. The mission is designed to map the interior of the Moon to gain knowledge of its origin and structure.