Dragon Palace ÿ Decide They are dark carbonaceous asteroids with brightness or albedo not exceeding 4 or 5%.Both are the main goals of the mission ab bird 2 From the Japan Space Agency JAXA and OSIRIS-REx NASA’s purpose is to collect material from its surface and bring it to Earth.
By obtaining the high-resolution images necessary to select the ideal material collection area, in contrast to the surrounding dark terrain, both spacecraft found very bright rocks on the surfaces of the two objects.
Each task force analyzed these bright rocks and presented the results in two articles published simultaneously in the journal. Natural astronomy.
Researchers Julia deLeón, Juan Luis Rizos Garcia, Javier Licandro and Eri Tatsumi from the Institute of Astronomy of Canaria (IAC) and members of the image processing team (Image Processing Working Group, OSIRIS-REx IPWG) are the authors of these two articles.
He explained: “When the Hayabusa2 team was conducting an approach maneuver and using an optical navigation camera to take images, they found many glowing rocks in Ryugu.” Chen mi The lead author of this article introduced Ryugu’s results.
“We used multi-band images to analyze the colors in a total of 21 bright rocks larger than 10 cm in visible light, and divided them into two spectral groups: carbonaceous and rocky. The researchers added that the six pieces belonging to the second group The rock is very bright and exhibits a spectrum similar to ordinary chondrites, which has been confirmed by the data obtained with the NIRS3 spectrometer.
Carbonaceous chondrites are mainly composed of anhydrous and shiny silicates, such as pyroxene and olivine.
“In the area closest to the sun in the main asteroid belt, there is an asteroid asteroid, the Nysa-Polana-Eulalia complex, which consists of a mixture of carbonaceous (or primitive) and rocky asteroids. We believe that Ryugu originated from Polana (primitive ) Family, so in the region, there may be an impact between these two types of asteroids. Tatsumi clarified that this could explain the presence of shiny materials on the surface of Ryugu.
Matter of the Bennu asteroid Vesta
Similarly, the abnormal rock on the surface of Bennu first caught the attention of the OSIRIS-REx team in the image of the OCAMS instrument. They found six very bright rocks ranging in size from 1.5 to 4.3 meters.
They analyzed the light emitted by these rocks with visible light and infrared spectrometers (OSIRIS-REx Visible infrared spectrometer, OVIRS) for more information about its composition. The spectrum of the rock is similar to that of pyroxene, and it is also similar to the spectrum observed on the surface of Vesta (one of the largest objects in the asteroid belt), while steroids are small fragments of Vesta that are caused by collisions with its surface. produced.
Daniella DellaGiustina, a co-author of the Lunar and Planetary Laboratory at the University of Arizona, said: “We found six rocks in Bennu’s southern hemisphere and near the equator, ranging in size from 1.5 to 4.3 meters.” “These rocks are brighter than the rest of Bennu. It’s much more, and it matches Vesta’s material.”
Although various possibilities have been evaluated, “Our main hypothesis is that Bennu inherited this material from its parent asteroid after the steroid (fragment of Vesta) hit the parent,” Hannah Kaplan of NASA Goddard Space Flight Center explain. “Then, when the parent asteroid was devastated, some of its fragments piled up on Bennu under its own gravity, including Vesta’s pyroxene.”
These are the first discoveries of foreign matter from asteroids such as Ryugu or Bennu, which are considered “debris piles” or Pile of rubble.
“Asteroid type Pile of rubble He explained that they are the result of the catastrophic collision of the larger parent object and the subsequent regrouping of these smaller fragments due to gravity. Julia De Leon.
This means that in the process of creating the asteroid type, the parent body and the material that hit the asteroid can be mixed together. Pile of rubble.
The OSIRIS-REx team discovered exogenous basalt in Bennu, and the Hayabusa2 team discovered chondrite-like material in Ryugu. He said: “Although both asteroids originated in the innermost region of the asteroid belt, these two materials are almost never produced in the same asteroid, which indicates that the collision objects and collisions of Longgu and Bennu History is different,”.
The Hayabusa2 mission successfully conducted two contact maneuvers from February 21 to July 11, 2019 to collect material from the surface of Ryugu. The spacecraft is currently returning to Earth and will arrive with the samples in December this year.
For its part, the OSIRIS-REx mission will conduct its first sample collection attempt in Bennu in October this year, and is scheduled to return to Earth in 2023.
Chenmi said: “The collected samples may include a small amount of foreign matter found in these luminous rocks, and their analysis will reveal the story of these two amazing asteroids in detail.”
In contrast to dark terrain, images of different types of shiny rocks on the surfaces of Ryugu (left) and Bennu (right). / Hayabusa2 (JAXA) / OSIRIS-REx (NASA)