More than 100 missions targeted at Earth's moon have been launched by space explorers since the late-1950s. NASA landed a total of 12 men on the lunar surface, collecting more than 800 pounds of moon rocks and lunar soil samples. But still, the moon remains a mystery, especially its formation. NASA's new mission aims to find out exactly how the moon came to be with the Gravity Recovery and Interior Laboratory, or GRAIL, part of NASA's Discovery Program.
Two probes, GRAIL-A and GRAIL-B, have successfully entered the lunar orbit, and will begin measuring the moon's gravity to indicate what's below the surface. NASA scientists expect to get the most detailed maps of the moon's uneven gravitational field and insight into its interior down to the core. But the actual data collection won't begin until March, after the space probes refine their positions and are circling just 34 miles above the surface.
To find out more about the GRAIL mission, check out their website, or click on the link below for more information.