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The solar system is an overcrowded place. The Earth is perhaps the only planet populated by humans, but many worlds harbor robots – rovers and landers and orbiters, collecting data for astronomers. The asteroid (162173) Ryugu joined them last summer and is hosting the Japanese spacecraft Hayabusa2. The mission has already gathered a lot of interesting data.
Now, according to a report Thursday in Science, we have some additional information about the diamond shaped Ryugu. The MASTER-Mobile Asteroid Surface Scout (MASCOT) lander from Hayabusa2, which landed last October, took several photos along the way. An international team of scientists analyzed them to get new information about the ancient world, helping them understand its violent past and even learn a little about the ancient solar system.
Rocky Landing
The descent of MASCOT on Ryugu was surprisingly low: Hayabusa2,
already in orbit, simply "let go" the undercarriage and let it fall to the surface.
The robust device, packed with a camera (named MASCam) and other instruments,
fell slowly, falling freely at about 134 feet for about 6 minutes before
land with a thud. He bounced another 56 feet before finally reaching a
rest.
Everything was done on purpose. The German Aerospace Center designed MASCOT for the hard journey, and took pictures throughout the course. The landing gear also carried a rotating mass that could reorient and even move the small boat, allowing it to collect data from various locations. And thanks to the proven methods of flash photography, the machine can even take pictures in the dark. After more than 17 hours and some extra jumps, the piles of MASCOT went out and this part of the mission was over.
Now, the researchers have combined and analyzed the photos – as well as the Hayabusa2 data – to carefully reconstruct the MASCOT course above and at the surface of Ryugu, allowing them to contextualize the close-up photos of the surface of the asteroid.
«MASCam images acquired during the descent and rebound
reveal a surface covered with rocks and blocks of different lithologies "or
characteristics, write the authors. "The rocks appear bright, with
faces and sharp edges, or dark, with a friable and friable surface like a cauliflower.
the distribution of both was approximately equal across all areas captured by MASCam.
The images also show a marked lack of finer rocks, such as dust or sand. Ryugu is pretty much just a collection of rocks and rocks, with nothing smaller now on the surface.
Search Ryugu
These results are revealing. The rock dichotomy confirms earlier ideas that Ryugu had a violent birth. The authors suggest that the asteroid is perhaps the result of the collision of two parent bodies that explain the two types of rocky materials scattered throughout. Or perhaps it is formed of a single body with radically different internal temperature and pressure conditions, which resulted in a "catastrophic disruption and redistribution, also resulting in the creation of two types of material ".
The study of the compositions of these rocks also revealed small
Luminous "inclusions", common in meteorites supposed to come from asteroids. Because
aquatic environments tend to destroy inclusions, their presence on Ryugu suggests
that the past of this asteroid was probably drier.
Finally, there is this lack of finer materials. Simple friction and other forces in space should produce such smaller particles. Their absence suggests that a process is taking them off – but the authors do not really know what that might be. "The absence of dust is not easy to explain," they write.
Ryugu is an asteroid close to Earth, which means that its orbit takes it close to our planet. The better we understand its composition and what is happening on its surface, the better we prepare ourselves in case one of the thousands of other NEA approaches dangerously. Asteroids are also remarkably preserved, because there is not much that erodes them in space. By studying them, astronomers are also studying the conditions that prevailed in the early days of the solar system, when most asteroids were formed.
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