The GRAIL mission consists of two spacecraft, GRAIL-A and GRAIL-B, which have been placed into orbit around the Moon. As the two GRAILs circle the moon, changes in topography (mountains and valleys) will create fluctuations in gravitational pull resulting in slight movements to and away from each other. The change in velocity created by the movements will be measured and translated into maps which will help scientist gain a better understanding of the moon.
The the spacecraft are about the size of a washing machine. The measurements they take are very precise, down to a couple microns (fractions of a hair). Each craft is also fitted with two video cameras (MoonKAM's). The videos created (and the MoonKam cameras) are specifically designed for a public outreach program by NASA.
The videos created (and the MoonKam cameras) are specifically designed for a public outreach program by NASA. The missions two primary goals are to create lunar thermal imaging maps and to educate the public about the moon. The two GRAIL spacecraft were launched into orbit on September 10, 2011 at 9:08 am.
The spacecraft took about three and a half months to reach the moon after being launched and spent another 2 months getting synchronized for their gravitational measuring task. The project will take approximately 82 days to complete. NASA will continue to present video from the two GRAIL spacecraft as part of their public education program.