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Hayabusa2 thermal imaging shows asteroid Ryugu is porous inside: research

Thermal imaging of the asteroid Ryugu is seen in this image taken by the space probe Hayabusa2. The blue hued sections indicate lower temperatures, and the red hued sections indicate higher temperatures. (C) Okada et al., Nature 2020
An image of the asteroid Ryugu taken by the space probe Hayabusa2 is seen in this image provided by the Japan Aerospace Exploration Agency, the University of Tokyo and others.

TOKYO -- The asteroid Ryugu is reportedly porous in structure, according to observations made by the Japan Aerospace Exploration Agency's (JAXA) Hayabusa2 probe which were published in the online edition of the U.K. science journal "Nature" on March 17.

Tatsuaki Okada, an associate professor at JAXA, described it as "like instant coffee that crushes into fine pieces when picked up."

The team behind the research observed the surface temperature of Ryugu between June and October 2018 using an infrared camera built into Hayabusa2. In the day, it reached as high as 60 degrees Celsius, and at night its temperature fell to around minus 50 C.

Taking into consideration the shape of the asteroid's face, the team analyzed how it accumulates and emits the sun's heat from its surface. They found that it contains properties which make it very easy for the celestial body to heat up and cool down. This suggests that boulders and other material covering its surface are of low density and with many holes, according to the team.

Research up to now has revealed that Ryugu was apparently formed after rocks and other material generated from destroyed small celestial bodies came together. Because the surface of the asteroid is almost all covered in porous rocks and other material, the team now hypothesizes that the prior celestial body it formed from was also porous.

The team also said there was a possibility that the solar system began forming some 4.6 billion years ago as gas and dust came together, and that the structure of asteroids like Ryugu is indicative that they were in a process of evolving into more solid objects, like our own planet.

(Japanese original by Tomohiro Ikeda, Science & Environment News Department)

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