After a journey of nearly five months, taking it far beyond the Moon and back, the little CAPSTONE spacecraft has successfully entered into lunar orbit.

“We received confirmation that CAPSTONE arrived in near-rectilinear halo orbit, and that is a huge, huge step for the agency,” said NASA’s chief of exploration systems development, Jim Free, on Sunday evening. “It just completed its first insertion burn a few minutes ago. And over the next few days they’ll continue to refine its orbit, and be the first cubesat to fly and operate at the Moon.”

This is an important orbit for NASA, and a special one, because it is really stable, requiring just a tiny amount of propellant to hold position. At its closest point to the Moon, this roughly week-long orbit passes within 3,000 km of the lunar surface, and at other points it is 70,000 km away. NASA plans to build a small space station, called the Lunar Gateway, here later this decade.