Two separate studies of the Moon have identified ideal places for a lunar colony. In 2011, NASA's Gravity Recovery and Interior Laboratory, also known as GRAIL, consisting of two spacecraft, Ebb and Flow, mapped the gravitational field of the Moon in great detail. In 2007, the Japanese space agency, JAXA, used the spacecraft Kaguya, to map the Moon from orbit using a magnetometer, radar, and imaging instruments.
volcanism that create lava tubes and
pit craters or sinkholes.