The near-Earth asteroid Bennu comprises stardust that’s older than our photo voltaic system, in addition to natural supplies and ices from interstellar area, three contemporary research of the asteroid’s pattern supplies present.
Scientists all around the world have been poring over samples of Bennu ever since materials from the asteroid was delivered to Earth in 2023, courtesy of NASA’s OSIRIS-REx mission, which flew alongside the asteroid earlier than briefly touchdown on it and scooping up samples in 2020.
The findings present a glimpse on the situations within the cosmos earlier than our photo voltaic system arose 4.6 billion years in the past and reveal extra concerning the guardian physique that generated the 1,600-foot-wide (almost 500 meters) asteroid.
A violent previous
The primary of the three papers, printed Aug. 22 within the journal Nature Astronomy, suggests Bennu’s ancestor broke aside in a violent collision, after an advanced historical past. That older physique contained supplies from a variety of distinct environments: near the solar, removed from the solar however nonetheless inside our photo voltaic system, and past our photo voltaic system in interstellar area.
Scientists noticed these places by isotopes, or factor varieties, within the pattern of Bennu’s mud. Isotopes that originated within the photo voltaic system had a special make-up than those who got here from interstellar stardust, for instance.
“All of those constituents had been transported nice distances to the area that Bennu’s guardian asteroid fashioned,” Ann Nguyen, co-lead creator of the paper and a planetary scientist at NASA’s Johnson House Middle in Houston, mentioned in a NASA assertion.
Associated: James Webb telescope reveals that asteroids Bennu and Ryugu could also be elements of the identical gigantic area rock
Scientists counsel the guardian asteroid fashioned within the outer photo voltaic system, possible past Jupiter and Saturn. However then got here a cataclysmic occasion: “We predict this guardian physique was struck by an incoming asteroid and smashed aside,” co-lead creator Jessica Barnes, an affiliate professor on the College of Arizona’s Lunar and Planetary Laboratory, mentioned in an announcement from the College of Arizona.
After the preliminary affect, “the fragments re-assembled, and this might need repeated a number of occasions,” Barnes added. Ultimately, a few of the surviving supplies coalesced into Bennu.
Bennu vs. Ryugu
The second paper, printed Aug. 22 within the journal Nature Geoscience, in contrast Bennu with primitive meteorites, in addition to with asteroid Ryugu, from which samples had been collected by the Japan Aerospace Exploration Company’s Hayabusa2 mission.
The guardian asteroids for Ryugu, Bennu and the meteorites possible arose in a “related, distant area of the early photo voltaic system,” NASA officers wrote within the assertion from the area company. However Bennu differs from the opposite sampled our bodies in some methods, suggesting that “this area modified over time, or didn’t combine in addition to some scientists have thought,” they mentioned.
Particularly, Bennu’s supplies from the guardian asteroid modified dramatically as they got here into contact with water, the second research confirmed.
“Bennu’s guardian asteroid collected ice and mud,” Tom Zega, co-leader of the second paper and a professor of planetary sciences on the College of Arizona, mentioned within the NASA assertion. “Ultimately that ice melted, and the ensuing liquid reacted with the mud to type what we see in the present day: a pattern that’s 80% minerals that include water.”
“We predict the guardian asteroid collected quite a lot of icy materials from the outer photo voltaic system,” Zega added, “after which all it wanted was a little bit bit of warmth to soften the ice and trigger liquids to react with solids.”
Micrometeorites
The third paper, printed Aug. 22 within the journal Nature Geoscience, traced ample proof of micrometeorites placing Bennu. These tiny rocks left behind microscopic craters and “affect melts” — bits of rock that was once molten — on the surfaces of the pattern. Researchers additionally noticed traces of the photo voltaic wind — the fixed stream of particles coming from the solar — represented within the samples.
“The floor weathering at Bennu is occurring rather a lot sooner than standard knowledge would have it, and the affect soften mechanism seems to dominate, opposite to what we initially thought,” mentioned co-author Lindsay Keller, a planetary scientist at NASA’s Johnson House Middle.
Moreover, whereas Bennu itself doesn’t host life, the research might assist scientists learn the way life arose on our planet, mentioned Michelle Thompson, second lead creator of the paper and an affiliate professor at Purdue College who focuses on area weathering.
“Asteroids are relics of the early photo voltaic system. They’re like time capsules,” Thompson mentioned in a assertion from Purdue. “We are able to use them to look at the origin of our photo voltaic system, and to open a window to the origin of life on Earth.”
