After a 17-month rendezvous with an asteroid hurtling through space some 200 million miles from Earth, Japan’s Hayabusa2 spacecraft is on its way home.
In a tweet, Japan’s space agency (JAXA) described the spacecraft’s departure from the Ryugu asteroid on Wednesday as “an emotional moment.”
But Hayabusa2 isn’t coming back empty-handed. Assuming its homecoming is as successful as the rest of its mission up to now, the spacecraft will bring with it rock samples collected directly from the 900-meter-wide space rock. It’s hoped the samples will give scientists new insight into the origins and evolution of the solar system and the building blocks of life, and also lead to the further development of deep-space exploration technologies.
Hayabusa2 reached Ryugu in June 2018 after a journey of three-and-a-half years. In February 2019 the spacecraft made a successful landing on the asteroid, a feat that was greeted with rapturous applause by engineers and scientists at the Tsukuba Space Center near Tokyo. The spacecraft also put several small landers onto the asteroid to collect a variety of data from the rock that it could transmit back to Earth.
Shortly before the historic descent onto Ryugu, Hayabusa2 fired what was can be loosely described as a 2-kilogram bullet into the asteroid to throw up rock particles that it later collected, making it the first-ever mission to successfully gather subsurface samples from an asteroid.
The spacecraft is expected to come close to Earth in about 12 months from now. When it does so, it’ll fire a 40-cm-wide capsule containing the rock samples toward Earth, allowing Hayabusa2 to remain in space for a possible future mission.
The final part of the current mission will involve locating the all-important capsule, which is expected to come down somewhere in the Australian outback.
The good news is that JAXA has form when it comes to the final stages of a mission like this. In 2010, Hayabusa2’s predecessor returned with a capsule containing tiny particles taken from the surface (not the subsurface as with Hayabusa2) of another asteroid. The capsule, which also came down in the Australian outback, transmitted a beacon signal that enabled scientists to locate it the following day.