Japanese Probe Drops Off Robots on Asteroid’s Surface

One of Japan’s most ambitious space missions just reached an important milestone. The Hayabusa2 probe has successfully deployed a pair of tiny robots destined to explore the surface of the asteroid Ryugu. These robots are just the first of many instruments Hayabusa2 will drop off on the surface, but the ultimate goal of the mission is to return samples of Ryugu to Earth.

Hayabusa2 dropped the robots off after descending to an altitude of just 180 feet (55 meters). It ejected a “drum” called MINERVA-II1 that contained both robots known as MINERVA-II1A and MINERVA-II1B. The Japanese Space Agency (JAXA) confirmed the landing pod separated successfully last week, but the fate of the robots is was unknown. The asteroid’s rotation took the landing site out of range before the Hayabusa2 probe could get images from the rovers. JAXA confirmed over the weekend that both robots were operational and on the surface. 

The robots could be called rovers, but they don’t work like the rovers we send to other planets. Ryugu is only about half a mile across, so it doesn’t have enough gravity for a robot to roll around on wheels. Instead, MINERVA-II1A and MINERVA-II1B are essentially tiny wheels. The drum-shaped robots contain motors that let them shift their weight to hop along the surface. A regular wheeled robot would just float away, but the 1A and 1B robots should be able to remain on the surface indefinitely. JAXA says each of these hops will send the robot hurtling through the air for about 15 minutes. MINERVA-II1A sent back that image below, captured as it hopped across the surface.

Both rovers contain multiple cameras and temperature sensors to map Ryugu. JAXA will provide an update on the robots when they are next in range of Hayabusa2. MINERVA-II1A and MINERVA-II1B are safe and sound on the surface of Ryugu, but they won’t be alone for long. The Hayabusa2 mission includes several rounds of robot landings. Next month, JAXA plans to release a German lander called MASCOT. It has a similar hopping mechanism, but its instruments are focused on the geology of the asteroid. Later, Hayabusa2 will drop another drum container with additional Minerva bots.

Next year, JAXA will begin collecting samples with the spacecraft. The first two consist of floating down to the surface, and then firing off projectiles to launch dust toward the probe. The third requires Hayabusa2 to collect material that’s currently buried beneath the surface. It will use a small explosive slug to make a crater before diving in to scoop up material. In total, JAXA hopes to send 100 milligrams of dust back to Earth.

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