The Japanese probe Hayabusa2 has successfully collected material from below the surface of asteroid Ryugu, after completing its second successful touchdown on the small near-Earth object today at 1.30am UTC. The spacecraft shot a projectile into the surface of the asteroid earlier this year.
This is the first time we have collected subsurface material from an object beyond the Moon, and the sample, along with the previously collected surface ones, will be brought back to Earth next year. As asteroids have remained unchanged for billions of years, studying this material will hopefully provide a window into the past.
"We've collected a part of the Solar System's history," Hayabusa2 project manager Yuichi Tsuda said at a press conference a few hours after the landing's success was announced.
In April, the probe released the Small Carry-on Impactor (SCI), a free-flying gun, and then moved to a safe distance on the other side of the asteroid. While it might seem like an over-the-top precaution, researchers were concerned that the projectile might quickly release enough debris to damage the probe.
The SCI shot a 2.5-kilogram (5.5-pound) copper projectile using 4.5 kilograms (9.9 pounds) of explosive propellant charge from a distance of 500 meters (1,640 feet). It created a crater roughly 2 meters (6 feet) in diameter. The probe didn’t land in this crater but in an area roughly 20 meters (65 feet) from its center, where the debris released by the impact landed.
This is a very important step in Hayabusa2's mission around Ryugu, but there are a few more to come before the craft leaves the asteroid. Later this month, the spacecraft will deploy a rover on the asteroid's surface. This will be the fourth one after the three successful deployments last year. It will then continue to study the asteroid until the final month of this year.
At that point, it will move into its homing orbit, which will take it near Earth in December 2020. It will release the sample, which will travel down through the atmosphere, and is expected to land in Australia. The probe is expected to return to Earth with plenty of fuel so there’s a possibility that it will be sent back into deep space to study another near-Earth object in future.
