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Asteroid Bennu continues to get more and more bizarre.
When NASA decided to send a probe to land on a space rock and bring back samples, it chose Bennu for its seemingly smooth surface: a perfect landing ground. But once the Osiris-Rex probe made the 200 million-mile journey to Bennu, the images it broadcast revealed a landscape covered with boulders and rocky fields.
NASA ultimately chose the flattest spot it could find to land, and the touch-and-go operation to gather material went well last month. But then the next surprise came: Bennu’s rock turned out to be incredibly soft, crumbling under the spacecraft when it hit the surface.
The spacecraft fired a nitrogen blast to send swirling rock and dust, that way it could catch some in its sample collection tool. But once again, the scientists were taken by surprise when it was discovered that the maneuver had produced so much material that dust and rock were opening the sample collection tool, allowing the precious alien dust to escape into space.
They managed to put the sample away before losing too much, but it wasn’t the least of the shocks. Recently, researchers from the University of Colorado concluded based on the data Osiris-Rex collected in the two years it has been circling Bennu that the asteroid is likely hollow.
“It’s like there’s a void in its center that could fit a couple of soccer fields,” Daniel Scheeres, professor in the university’s Department of Aerospace Engineering Sciences who led the way, said in a press release. research.
Also, Bennu could fall apart.
‘The whole thing is flying away’
While Osiris-Rex is in orbit around Bennu, the spacecraft measured how much the asteroid’s gravity attracted him. At the same time, Bennu was also hurling pieces of rock the size of a marble from its surface. Those crumbs went into orbit around the asteroid, then some fell to its surface. By following their movements, the mission leaders were able to make calculations about Bennu’s strength of gravity.
Since gravity comes from mass, these two data sets allowed Scheeres’ team to calculate how the material is distributed within the asteroid.
Their results, published in the journal Science Advances on October 8 (before the brief Osiris-Rex landing), show that it is far from equal. The force of the rotation of the Bennu appears to push its material outward towards the surface. Some of the thinnest parts of the asteroid lie in its protruding equator.
Bennu completes one rotation every four hours and is getting faster and faster.
“You could imagine that maybe in a million years or less, the whole thing will fly away,” Scheeres said.
Bennu could keep secrets about the origins of life
An illustration of OSIRIS-REx orbiting the asteroid Bennu.
NASA’s Goddard Space Flight Center / Conceptual Image Lab
Bennu is one of the most potentially dangerous asteroids in our solar system, according to Osiris-Rex principal investigator Dante Lauretta, as it has a “non-negligible chance” of crashing into Earth during the 22nd century. Its frailty might be good news, though.
Studying Bennu could help future scientists come up with a plan to deflect the asteroid if it ever threatens to impact Earth. The research could also reveal new details about asteroid life: primordial piles of rock that coalesced from the remaining chunks that did not become planets. Such objects could hold secrets about how our solar system was formed and how life on Earth was born.
“We were hoping to find out what happened to this asteroid over time, which can give us a better insight into how all of these small asteroids are changing over millions, hundreds of millions, or even billions of years,” Scheeres said. “Our results have exceeded our expectations.”
Osiris-Rex has collected a lot of data that scientists have yet to review. The collected sample is expected to return to Earth in 2023.
An animation shows OSIRIS-REx releasing its sample return capsule for landing in the Utah desert on September 24, 2023.
NASA / Goddard / CI Lab
Assuming that the capsule containing the sample parachutes safely into the Utah desert as planned in a few years, NASA said it will retain some of the alien rock for future studies with as yet undeveloped technologies. The agency will ship the rest to labs around the world.
“It’s about understanding our origins, addressing some of the fundamental questions we ask ourselves as human beings,” Lauretta said before Osiris-Rex landed on the asteroid. “Where do we come from? And are we alone in the universe?”
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