Japan’s asteroid probe set to land

Japan’s Hayabusa2 probe began descending yesterday for its final touchdown on an asteroid.

A photo of asteroid Ryugu taken by a rover from the Japanese Aerospace Exploration Agency's Hayabusa2 spacecraft last September.

Japan’s Hayabusa2 probe began descending yesterday for its final touchdown on an asteroid, hoping to collect ­samples that could shed light on the evolution of the solar system.

After giving the go-ahead at 9.58am (10.58am AEST), the Japan Aerospace Exploration Agency said the probe had ­descended about 5km and was on track to touchdown today on the Ryugu asteroid, 300 million kilometres from Earth.

If successful, it will be the second­ time it has landed on the desolate asteroid as part of a complex mission that involved sending rovers and robots.

The mission hopes to collect pristine materials from beneath the surface of the asteroid that could provide insights into what the solar system was like at its birth 4.6 billion years ago.

To get at those crucial mater­ials, an “impactor” was fired from Hayabusa2 towards Ryugu in April in a risky process that creat­ed a crater on the asteroid’s surface and stirred up material that had not previously been ­exposed to the atmosphere.

“This is the second touchdown, but doing a touchdown is a challenge whether it’s the first or the second,” Hayabusa2 project manager Yuichi Tsuda said ­before the mission.

Hayabusa2 landed briefly on Ryugu in February and fired a bullet into the surface to puff up dust for collection, before blasting back to its holding position. The second touchdown requires special preparations because any problems could mean the probe loses the precious materials gathered during its first landing.

A photo of the crater taken by Hayabusa2’s camera shows that parts of the asteroid’s surface are covered with materials that are “obviously different” from the rest of the surface, mission manager Makoto Yoshikawa said.

The probe is expected to make a brief touchdown on an area 20m from the centre of the crater to collect the unidentified materials believed to be “ejecta” from the blast.

The touchdown will be the last major part of Hayabusa2’s mission, which will end when the probe returns to Earth next year.

The size of a large refrigerator, and equipped with solar panels to keep it powered, Hayabusa2 is the successor to JAXA’s first asteroid explorer, Hayabusa — Japanese for falcon.

That probe returned with dust samples from a smaller, ­potato-shaped asteroid in 2010, despite various setbacks during its seven-year odyssey.

AFP