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Thursday, August 22, 2019
New images from asteroid probe offer clues on planet formation
The image shows the first image acquired by the DLR-developed MASCAM camera system during Hayabusa2's descent, shortly after separation from the landing module at a height of 41 meters with a viewing direction towards the south pole. Particularly striking is a huge block near the South Pole, which stands out clearly above the horizon line and which is named 'Otohime Saxum'. It is up to 100 meters tall. Credit: Jaumann et al., Science (2019) More
Photographs snapped by a shoebox-sized probe that explored the near-Earth asteroid Ryugu have offered new clues about its composition, insights that will help scientists understand the formation of our solar system.
The German-French Mobile Asteroid Surface Scout (MASCOT) hitched a ride on Japan's Hayabusa2 spaceship, touching down on the 900-meter (3,000 feet) wide asteroid, whose orbit lies mostly between Earth and Mars, on October 3, 2018.
Ryugu's gravity is 66,500 times weaker than Earth's, and the forward motion of wheels would have launched MASCOT back into space.
So it instead hopped around the surface using the tiny amount of momentum generated by a metal swing arm attached to its boxy body, which weighed 10 kilograms (22 pounds).
In addition to taking temperature readings and other measurements, MASCOT reeled off a series of pictures showing the asteroid is covered with rocks and boulders that fall into one of two categories: dark and rough with crumbly surfaces that resemble cauliflowers, or bright and smooth.
"The interesting thing there is it really shows that Ryugu is the product of some kind of violent process," Ralf Jaumann of the German Aerospace Center and the lead author of a paper describing the findings in the journal Science on Thursday, told AFP.
Ryugu may be the "child" of two parent bodies that collided, broke up, and then came back together through gravity, the researchers say.
Another theory is that it could have been struck by another body that created different interior temperature and pressure conditions, resulting in the two types of material.
Many of the rocks also contained small blue and red "inclusions"—material that was trapped in the rock during its formation—making them extremely similar to a type of rare, primitive meteorites found on Earth called carbonaceous chondrites.
"This material is primitive material—it's the very first material of the solar nebula," or the cloud of interstellar dust and gas that formed the planets of our system, said Jaumann.
The second image of the DLR-developed MASCAM camera is directed obliquely downward on the asteroid Ryugu and covers areas east of the descent route. Compared with the first image, it is clear that MASCOT moved turbulently towards Ryugu, as expected, thus performing turns and rollovers. The images show a huge boulder, which occupies the eastern (right) edge of the image and is several tens of meters in length. On the bottom left is MASCOT's shadow, which the Sun behind the landing probe is projecting onto the asteroid surface: MASCOT is 30 centimeters long. Ryugu is a body with no atmosphere, so the outlines of MASCOT are sharp in the shadows projected onto the asteroid surface. Credit: Jaumann et al., Science (2019) More
Before the first contact with a large rock on Ryugu, DLR's MASCAM camera photographed the area of the descent route with a backward-looking view. Credit: Jaumann et al., Science (2019) More
The fifth image acquired by the DLR-developed MASCAM camera system was taken shortly after the first contact with the ground, just a few meters above the surface of Ryugu. Just as in the images from higher altitudes, no fine material, known as regolith, can be seen, even in the immediate vicinity of the surface. Regolith is formed on atmosphere-less bodies due to their permanent exposure to high-energy particles from space or micrometeorites due to the weathering of coarser material into dust. Instead, the area is extremely rugged and full of sharp blocks. Credit: Jaumann et al., Science (2019) More
Image acquired by the DLR-developed MASCAM camera system, taken at night. Credit: Jaumann et al., Science (2019) More
Hayabusa2 will eventually return to Earth carrying samples, but MASCOT's observations provide information on the material's original geologic context: how it is exposed to temperature changes, how it gets weathered, and so on.
Why is this important?
"We don't know how planets formed in the beginning," said Jaumann.
"And in order to understand this, (we must) go to the small bodies, these primitive bodies, primordial in their history in their evolution, in order to understand the first 10 to 100 million years of planetary formation."
Citation: New images from asteroid probe offer clues on planet formation (2019, August 22) retrieved 22 August 2019 from https://phys.org/news/2019-08-images-asteroid-probe-clues-planet.html
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