As part of its latest science campaign, NASA sent two spacecraft in September last year to obtain accurate data about lunar gravity; codenamed the Gravity Recovery And Interior Laboratory (Grail), both probes are now in full swing, informs mission head Maria Zuber at the Massachusetts Institute of Technology.

One of the main purposes of the $496m mission is to get a clear picture, literally, of the dark side of the moon – the one which never faces the earth. Based on the feedback provided by the probes, scientists hope to untangle the mystery as to why the visible lunar surface seems plainer than the other side.

NASA officials are hopeful that the spacecraft will be able to provide accurate information about lunar gravity that appears to be inconsistent. For the next three months the probes will orbit the moon at an altitude of 35 miles from the surface of the satellite, sending data that would allow the mission controllers to closely track the miniscule variations in distance between the two bodies.

Since the probes will be within the gravitational field of the moon, they might help calculate the exact lunar gravity, NASA hopes. It may also help scrap the earlier speculation that our planet once had two moons that subsequently slammed into each other to form the mountainous terrain on the far side.

According to Zuber, experts involved in the Grail mission are happy so far about the way everything has unveiled and are waiting eagerly for more data so they can start assessing in-depth.