The mission team say goodbye to Ryugu ©ISAS/JAXA

It’s time to come home. Japan’s Hayabusa 2 spacecraft has begun its departure from the asteroid Ryugu, carrying two samples of the space rock back to Earth for analysis. “This is an emotional moment!” the team posted on the mission’s Twitter account.

The probe will take about five days to exit the sphere of Ryugu’s gravitational influence. During this time, it will make “farewell observations” as it slowly moves away from the small world that has been its home for the past 17 months. Then it will fire its main engines for the journey back to Earth, which will take about a year.

The original Hayabusa mission returned the first asteroid samples to Earth in 2010. This time, the probe has sampled the interior of and asteroid, first by firing a tantalum bullet into the rock, then dropping an explosive charge that disturbed an area about 20-metres wide on its surface.


Ryugu is a relic from the formation of our solar system. Its surface has been altered by millions or billions of years of exposure to cosmic radiation, but its pristine interior could tell us about the make-up of the early planets.

The mission will also act as a demonstration for the nascent space mining industry. The ability to obtain resources such as water, iron and silicon on asteroids may be essential for humanity to make a home on other worlds.

Another asteroid explorer is following close behind. NASA’s OSIRIS-Rex spacecraft is currently in orbit around the asteroid Bennu and is set to grab its first sample in the middle of 2020.