A Japanese spacecraft that will return a sample of an asteroid to Earth has arrived at its target – the diamond-shaped Ryugu, 280 million kilometers (175 million miles) from Earth.
The spacecraft, Hayabusa 2, is now just 20 kilometers (12 miles) away from Ryugu, where it will hover in place to study the object. According to the Japanese Aerospace Exploration Agency (JAXA), scientific observations and surveying of the asteroid will now begin.
“JAXA confirmed Hayabusa2, JAXA's asteroid explorer, rendezvoused with Ryugu,” they said in a statement. “On June 27, 2018, JAXA operated Hayabusa 2 [sic] chemical propulsion thrusters for the spacecraft's orbit control.”
The spacecraft is now maintaining a constant distance from Ryugu, which appears to have a pretty unique shape. The huge bulge at its equator suggests it once spun quite rapidly, about once every three or four hours. Today it spins at 7.5 hours, but it’s not clear why it has slowed down.
“The project team is fascinated by the appearance of Ryugu and morale is rising at the prospect of this challenge,” the mission’s project manager, Yuichi Tsuda, said in a statement. “Together with all of you, we have become the first eyewitnesses to see asteroid Ryugu. I feel this amazing honor as we proceed with the mission operations.”
Now that the spacecraft has arrived, the exciting mission can begin. Onboard Hayabusa 2 are five separate landers, which will be deployed to the asteroid over the next year.
In September at the earliest this year, it will deploy three rovers to the surface and an additional German-built lander, to study it up close. Then, in spring next year, it will release an impactor and attempt to create an artificial crater on the asteroid.
If successful, the spacecraft will then lower itself into the crater, and fire a projectile on the end of an arm to kick up material from the crater and collect it. This material, from under the surface, will be relatively fresh and should give scientists an insight into the interior of an asteroid.
The rotation and shape of the asteroid will make the landings somewhat tricky. The shape means that its gravitational force does not point directly down, while an abundance of craters will mean care will need to be taken selecting a landing site.
Hayabusa 2 is scheduled to depart the asteroid in December 2019, delivering a capsule containing samples from the asteroid to Earth in 2020. This timetable is subject to change, though, depending on how operations at the asteroid progress.
The mission is the successor to the Hayabusa mission in the 2000s, which returned minimal samples from the asteroid Itokawa. This time around scientists will be hoping from a bigger haul – and so far, everything appears to be on track.