GRAIL:
Goals: GRAIL will fly twin spacecraft in tandem around the Moon to precisely measure and map variations in the Moon's gravitational field. This detailed information will reveal differences in density of the Moon's crust and mantle and will help answer fundamental questions about the Moon's internal structure, thermal evolution and history of collisions with asteroids.

The new knowledge about lunar gravity will significantly assist the planning of any future manned or unmanned missions to land on the Moon. The data can be used to help target desirable landing sites and to program precision lunar navigation and landings.

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2011:  Launch Status:  In Development Show All Dates for GRAIL		22 May 2008:  Lunar GRAIL 11 Dec 2007:  New NASA Mission to Reveal Moon's Internal Structure and Evolution
GRAIL is the lunar counterpart of the successful GRACE mission (right), twin satellites launched in 2002 to make detailed measurements of Earth's gravity field. GRAIL and GRACE is part of NASA's Discovery Program of lower-cost, highly focused planetary science investigations. Studying the Moon is key to understanding how terrestrial planets evolved because it is the most accessible body that preserves a surface record spanning most of our solar system's history.		Solar System Bodies: Earth's Moon GRAIL Multimedia Gallery NASA Discovery Program Disovery Program GRAIL Mission Homepage Science Feature: Lunar Grail