Japan’s Hayabusa2 asteroid probe has already accomplished a lot. The spacecraft successfully traveled to its target, a space rock known as Ryugu, where it entered orbit and completed some daring sample-gathering maneuvers. Earlier this month, the probe departed from the asteroid and today it begins its journey back to Earth.

As Space.com reports, Hayabusa2 recently fired up its ion propulsion system in a brief test to ensure it’s ready to push the spacecraft back home. The test went smoothly, and today the Japanese space program JAXA will hit the throttle.

One of the mission’s primary goals is to not only retrieve samples of asteroid material from Ryugu — a task the probe pulled off despite the tricky nature of snatching bits of dust and debris from an object flying through space — but also return that material to Earth. To truly pull off this historic mission, JAXA needs the probe to fly all the way back to Earth and deliver the samples.

It’s a long trip. Hayabusa2 spent well over three years traveling to Ryugu, chasing it down as it orbits the Sun. The trip back will be a bit quicker, only taking roughly a year to get into a position to release a capsule that holds the asteroid material samples. When that happens in December 2020, the sample capsule will come cruising down to Earth in Australia.

There’s still a lot of work to be done, and nothing is guaranteed. JAXA will be keeping a close eye on the spacecraft as it speeds home over the next year, and the eventual release and capture of the sample capsule will ultimately determine whether the mission can be considered a total success. Hayabusa2 has delivered in every way up to this point, so there’s no reason to think that will change.