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Japanese mission becomes first to land rovers on asteroid

Twin probes from Hayabusa2 mission have sent back their first pictures from Ryugu’s surface.

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Blurred photo from Rover-1A taken during a hop showing asteroid Ryugu to the left. The bright white region is due to sunlight.

MINERVA-II rover 1A took this image during a hop on the asteroid Ryugu.Credit: JAXA

Japan’s asteroid mission Hayabusa2 has become the first to land moving rovers on the surface of an asteroid.

On 22 September, the Japan Aerospace Exploration Agency (JAXA) tweeted confirmation that the mission’s twin rovers, called MINERVA-II 1A and 1B, had landed safely on the space rock Ryugu, and that both were moving on the surface.

The Hayabusa2 mothership deployed the small probes late last week as it dropped to just 55 metres above the surface, later pulling up to a higher orbit.

Mission controllers lost communication with the MINERVA rovers in the hours after deployment. The team said that the silence was probably down to the landers being on the far side of the asteroid, as seen from the orbiter.

But the hexagonal rovers have now sent back their first, slightly blurry, colour images of the surface and made their initial ‘hop’ — their primary means of movement on the rock’s surface. The probes use rotating motors to make jumps, each lasting some 15 minutes owing to the body’s low gravity.

Hayabusa2’s shadow on the asteroid Ryugu during the MINERVA-II deployment operation

Hayabusa2’s shadow is seen on the asteroid Ryugu during the MINERVA-II deployment operation.Credit: JAXA

As well as taking images of the asteroid, the landers are designed to measure its temperature.

Before it leaves Ryugu next year, the Hayabusa2 mothership will release two more landers and, in late October, will touch down on the surface itself to collect a sample to bring back to Earth.

Scientists hope that studying the 1-kilometre-wide-asteroid, which is made up of primitive material from the early Solar System, will help them to understand the origins and evolution of Earth and other planets.

This is not the first time scientists have explored an asteroid. In 2005, the mission’s predecessor, Hayabusa, landed on the surface of a smaller asteroid, called Itokawa, and collected a sample that it later returned to Earth. But this is the first time a lander has moved on an asteroid’s surface.

JAXA scientists reported their joy at the rovers’ success. “I cannot find words to express how happy I am,” said Yuichi Tsuda, project manager for the Hayabusa2 mission, in a statement.

doi: 10.1038/d41586-018-06808-0
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Updates & Corrections

  • Update 24 September 2018: This story has been updated to note that the MINERVA II rovers have landed safely on the asteroid Ryugu.