Medical News
By Abigail Beall
Japan’s Hayabusa 2 spacecraft arrived at the asteroid Ryugu in 2018Akihiro Ikeshita/JAXA The most detailed pictures yet of the asteroid Ryugu have revealed something curious: it is surprisingly free of dust. Japan’s Hayabusa 2 spacecraft arrived at the asteroid in June 2018, dropped three landers and took a sample of dust from Ryugu’s surface. Now, pictures from one of the landers have revealed details about what the asteroid is made up of. From previous observations, scientists knew Ryugu’s composition was similar to that of a group of meteorites called carbonaceous chondrites, which make up less than 5 per cent of all meteorites that fall to Earth.
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But they were surprised about the detail of rock texture they were able to observe on the surface, says Ralf Jaumann at the German Aerospace Center’s Institute of Planetary Science in Berlin, who led the study. “Being able to see differently coloured bright inclusions in the rock, crumbly surfaces and smooth textures is amazing,” he says. The images show there are two kinds of rock on Ryugu’s surface, dark and rough or bright and smooth, and they both take up an equal share in the surface. The pictures also show the surface of Ryugu does not have a layer of dust, like there is on the moon, for example. This is strange because dust is expected to accumulate through various bumps and scrapes in space. Why it isn’t there is a mystery. The surface of Ryugu isn’t quite what we expectedAkihiro Ikeshita/JAXA One explanation could be that fine dust particles become charged due to solar radiation and and are removed by electrical forces, says Jaumann. Another possibility is that the release of volatile gasses from the surface might have blown the dust away. Or maybe, if the asteroid shakes as it travels through space, the dust could have gradually trickled into the interior of the asteroid, meaning we can’t see it. “At this point it is unclear which mechanism, is most probable for Ryugu,” says Jaumann. Journal reference: Science, DOI: 10.1126/science.aaw8627