Asteroid Ryugu “tanned” under the sunlight

Thanks to the data from the station “Hayabusa-2” the astronomers found that in the past the asteroid Ryugu was temporarily closer to the Sun than now, which led to the redness of the surface layer. The devices and images received by the station during the first operation of soil sampling from the asteroid. Article published in the journal Science.

Japanese space probe “Hayabusa-2” explored a 900-metre near-earth asteroid (162173) Ryugu, which refers to the S-type. The machine arrived to the asteroid June 27, 2018 and worked in orbit around him a year and a half, having at that time to bond with the surface of the Ryugu to take ground and landed on his four re-entry device. 13 November 2019, the station left the asteroid, it is expected that it will deliver a capsule containing soil samples into orbit at the end of 2020.

21 Feb 2019 hosted the first procedure of soil sampling with Ryuga. The station initially declined to 45 meters, then began to move along the surface to pre-planned point, and at the time of closest approach with the asteroid camera shot on it pathammavong tantalum bullet that was moving at a speed of about three hundred meters per second, and then took the dust and small debris sampling mechanism, and then returned to working 20-kilometer orbit.

A team of astronomers led by Tomokazu Morota (Tomokatsu Morota) analyzed the images obtained by the cameras onboard the station during the operation, as well as data collected by the spectrometer NIRS3. Scholars interested in the mechanical and chemical properties of the surface layer is fragmented Ryugu. It turned out that large boulders (up to one meter) were able to fly five meters, and a large part of the observed scatters the fragments were small pebbles and granules with a diameter of one to several millimeters. This high mobility of the regolith indicates that the adhesion force between boulders and pebbles can be very weak, it is consistent with the observed deficit of small (up to one hundred meters in diameter) craters on Ryugu and loss of substance on the slopes-preserved craters. Estimate the total mass raised clouds of small fragments formed by the action of the engines of the station and shot is approximately 12 kilograms.

Earlier data collected by the station showed that the surface of the Ryugu consists of two different types of substances, one of which appears reddish and the other bluish. Then the reason for such differences remains unknown. Image the asteroid’s surface obtained before and after first operation of the soil sampling, showed that her original color was more blue than the surrounding region, but became more red after sedimentation are raised from the surface of the dark thin grains. The comparison of images with spectral data allowed scientists to conclude that these small reddish grain initially focused on the surfaces of rocks or in cavities inside of them, and do not differ in composition from them.

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