GRAIL Twin Spacecraft -- Crust to Core Artist Concept

The Gravity Recovery and Interior Laboratory GRAIL mission utilizes the technique of twin spacecraft flying in formation with a known altitude above the lunar surface and known separation distance to investigate the gravity field of the moon.

The Gravity Recovery and Interior Laboratory GRAIL mission utilizes the technique of twin spacecraft flying in formation with a known altitude above the lunar surface and known separation distance to investigate the gravity field of the moon.