Japan's asteroid-hunter, Hayabusa2, recently. But what good is blowing a hole in an asteroid if you can't go down and grab some of the debris?
Hayabusa2 has already, but the material it nabbed was resting on the surface of the asteroid. To gain a better understanding of the material deeper below, they need to grab another.
In mid-May, Hayabusa2 attempted to drop a target marker on the surface of Ryugu, in a location where much of the debris settled. However, during the attempt, the spacecraft ran into some trouble and terminated its descent. The Japanese Space Agency (JAXA) confirmed that the target marker had not been placed -- and so Hayabusa2 couldn't ready itself to lean in and collect a new sample.
The target marker is incredibly important for Hayabusa2 to succeed in its touchdown, high-five and rock theft. Without the reflective ball to guide it, the spacecraft risks colliding with the asteroid or snagging itself on a rock.
Not content with the first failure, JAXA decided to try again. On May 29, they set the spacecraft to descend toward Ryugu at a pace of 40 centimeters per second for a second time.
The key to dropping the target marker is getting up close and personal with Ryugu. Hayabusa2 needed to reach a distance of around 10 meters before it would drop the target marker. It uses a special on board radar to determine exactly where it is in relation to the space rock. During a previously aborted attempt, the radar had experienced difficulty detecting this distance, and so the spacecraft ascended to save itself any drama.
During their second attempt on May 29, things went a lot more smoothly. At 7:38 p.m. PT, JAXA tweeted "the spacecraft turned to rise near an altitude of 10m. There is applause in the control room!"
Though JAXA is yet to confirm the separation of the target marker onto Ryugu's surface, Hayabusa2 was programmed to offload the reflective ball before it reached its lowest altitude of 10 meters. Thus, provided it carried out those commands, Hayabusa2 will be ready to return to the asteroid and collect a second sample in the coming weeks.
Japan's Hayabusa2 spacecraft has been. It's and to collect debris -- so it has already achieved big things. However, it's chief mission is to study and sample Ryugu, and then return to Earth with samples from the asteroid in late 2020. That makes the second sample collection a high stakes gambit, but with the target marker successfully deployed, JAXA will be hopeful of success.
The spacecraft is also looking to drop a second exploration rover, known as Minerva-II-2, on the asteroid at some point "after July."