Japan’s Hayabusa2 lands two rovers on asteroid Ryugu

The shadow of Japan’s Hayabusa2 spacecraft is cast on the surface of the C-type asteroid Ryugu during an initial close-range approach. The spacecraft deployed the first two of four small landers on 21 September. Image: JAXA

Japan’s Hayabusa2 asteroid sample return spacecraft descended to within about 180 feet of its target 21 September and dropped two small landers to the surface that promptly began hopping about, using on-board cameras and other sensors to make close-range observations.

Japanese flight controllers confirmed successful landings of the Hayabusa2’s MINERVA II-1 landers and posted initial photos from Rover-1A and 1B. The images, blurred because of the landers’ motion, revealed a dark rocky surface as the tiny robots descended and began hopping about their new home, 162173 Ryugu.

“Although I was disappointed with the blurred image that first came from the rover, it was good to be able to capture this shot as it was recorded by the rover,” Tetsuo Yoshimitsu, a Hayabusa2 program manager, said in an English version of comments posted on the project’s web page.

“Moreover, with the image taken during the hop on the asteroid surface, I was able to confirm the effectiveness of this movement mechanism on the small celestial body and see the result of many years of research.”

The carbonaceous near-Earth asteroid, discovered in 1999, is about 900 metres (3,000 feet) in diameter. Hayabusa2 reached the asteroid and began close-range observations in late June, nearly four years after launch in December 2014. Images from the spacecraft revealed an unusual-looking boulder-strewn body with rocky, roughly angular facets giving it a somewhat crystalline shape.

Hayabusa2’s Rover-1B capture this image of Ryugu as it began its slow fall to the surface shortly after release. The “misty” region at top left is due to reflected sunlight. Image: JAXA

The MINERVA II-1 landers were the first of four to be released by Hayabusa2. Both are drum-shaped spacecraft weighing 1.1 kilograms (2.4 pounds) each that are designed to hop short distances in Ryugu’s weak gravity using internal rotating masses. Each lander includes two cameras and temperature sensors. A third lander, known as Rover-2, will be deployed in October with a fourth known as MASCOT, following next year.

The Hayabusa2 mission has two major objectives: learning more about composition and evolution of primitive carbonaceous asteroids and testing novel technology for obtaining samples from deep space targets and returning them to Earth for detailed laboratory analysis.

The $271 million Hayabusa2 will do that by approaching to within a few feet of Ryugu, firing a projectile at the surface and then using a scoop-like device to collect a small sample of the ejecta.

If all goes well, the spacecraft will attempt to collect sub-surface material by releasing an explosive penetrator to blast out a small crater.Hayabusa2 then will drop down into the depression to collect pristine material unaffected by solar radiation and other “space weathering” factors. The samples will be returned to Earth at the end of 2020.

Rover-1A caught this chaotic image during a short hop on Ryugu’s surface. The bright area to the right is due to sunlight with blurring caused by the small spacecraft’s motion. Image: JAXA