Twin NASA spacecraft are set to blast into lunar orbit at the weekend on a mission to study the subterranean structure of the Moon in order to better understand the origins of planets.
The first Gravity Recovery and Interior Laboratory (GRAIL-A) will begin orbiting the Moon at 2121 GMT on December 31, followed by GRAIL-B on January 1 at around 2205 GMT, NASA said in a statement.

“This mission will rewrite the textbooks on the evolution of the Moon,” said GRAIL head researcher Maria Zuber, of the Massachusetts Institute of Technology, adding that the spacecraft were thus far performing well.

The $500 million pair of washing machine-sized satellites were launched on September 10 on a mission to map the Moon’s inner core for the first time.