NASA’s OSIRIS-REx spacecraft spotted strange colored rocks on the surface of the asteroid Bennu. After some investigation, the scientists found out where they most likely came from: a completely different asteroid from what we knew until now.
Since December 2018, the small spacecraft has been taking a close look at Bennu, an asteroid near Earth, only 500 meters wide. In October, Osiris-Rex will try to reach the asteroid’s surface to collect a sample.
“We found six boulders ranging in size from about 1.5 to 4.3 meters, scattered over the southern hemisphere of Bennu and near the equator,” he said in a statement. communique NASA Daniella DellaGiustina of Lunar & Planetary Laboratory, University of Arizona, Tucson and lead author of work recently published in Nature Astronomy.
“These boulders are much brighter than the rest of the asteroid Bennu and match the material from the asteroid Vesta,” said DellaGiustina. In fact, according to scans by the OSIRIS-REx suite of cameras, the rocks appeared to be ten times brighter than their surroundings.
During their investigations, analyzing a lot of surface scans, the OSIRIS-REx team woke up puzzled by the strange rocks they observed.
The vest, first discovered over two hundred years ago by German astronomer Heinrich Wilhelm Matthias Olbers, is one of the largest objects in the asteroid belt, measuring over five hundred kilometers from one end to the other. Scientists predict that it will represent about nine percent of the mass of the entire asteroid belt.
Thus, analyzing the readings of the OSIRIS spectrometer, the team found that the light rocks were probably made of mineral pyroxene, exactly the kind of material that had been spotted on Vesta and its smaller fragments – known as “vestoids” – that were agitated The vest was bombarded by smaller asteroids.
The team concluded that bright rocks are unlikely to form on Bennu itself because pyroxene is formed at extremely high temperatures. Bennu’s rocks, which contain mostly water-containing minerals, would not have experienced such temperatures. No strong impact could have led to these temperatures. In fact, such an impact would have broken Bennu.
If all goes according to plan, OSIRIS-REx will make its first attempt at sampling in October and bring it back to Earth in 2023.
It would not be the first time astronomers have observed bits of one asteroid on the surface of another. For example, the Japanese spacecraft’s Hayabusa 2 spacecraft saw darker material from a “type S” asteroid on the much darker Ryugu asteroid in 2018.
Due to the discovery, scientists could gather details about Bennu’s trajectory – how the rock’s orbit is affected by certain factors, including gravitational forces on nearby planets and small asteroid impacts. “Future studies of asteroid families, as well as the origin of Bennu, must reconcile the presence of Vesta-like material and the apparent lack of other asteroids,” said Dante Lauretta, OSIRIS-REx principal investigator at the University of Arizona in Tucson. .
“We look forward to the returned sample, which hopefully contains pieces of these interesting types of rocks,” Lauretta added.