NASA’s Gravity Recovery and Interior Laboratory (GRAIL) mission launched yesterday to map the Moon’s gravity field in exquisite detail.

The two solar-powered spacecraft, GRAIL-A and GRAIL-B, will reach their destination at the end of this year and then fly in tandem around the Moon, collecting data for almost three months.

“Since the earliest humans looked skyward, they have been fascinated by the moon,” said GRAIL principal investigator Maria Zuber from the Massachusetts Institute of Technology, Cambridge, in a statement provided by NASA. “GRAIL will take lunar exploration to a new level, providing an unprecedented characterization of the moon’s interior that will advance understanding of how the moon formed and evolved.”

For more about the GRAIL mission, see our curtain-raiser news story from a couple of weeks ago.