The first of two NASA robotic probe have began orbiting the moon in order to study the Moon’s inner core so as to better understand the origins of planets on Sunday.

The first Gravity Recovery and Interior Laboratory (GRAIL-A) began orbiting the Moon at about 0331 Indian Standard Time (IST), according to officials at NASA’s Jet Propulsion Laboratory in Pasadena, California.

As per sources, the next GRAIL-B was expected to follow suit on Monday at around 0335 GMT. Over the next two months, the two unmanned spacecraft will sent radio signals that allows the scientists to create a high resolution map of the Moon’s gravitational field, helping them to better understand its sub-surface features.