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A near-Earth asteroid called Bennu turns out to be full of surprises — most recently the fact that its surface resembles a crater of plastic balls, according to NASA scientists.
The new discovery comes after the space agency successfully collected a sample of the asteroid in October 2020.
During the historic assembly event, the sampling head of the OSIRIS-REx spacecraft sank 1.6 feet (0.5 meters) into the asteroid’s surface. Apparently, the exterior of Bennu is made up of loosely bound particles that are not bound together very securely, judging by what happened when the spacecraft collected a sample. If the spacecraft He didn’t fire his rocket back down after his quick gathering of dust and rocks, he may have sunk directly into the asteroid.
“By the time we launched our thrusters to leave the surface, we were still sinking into the asteroid,” Ron Blose, an OSIRIS-Rex scientist at the Johns Hopkins Applied Physics Laboratory in Laurel, Maryland, said in a statement. Blues is a co-author of a pair of July studies published in the journals Science and Science Advances about the discovery.
Bennu is an asteroid that resembles a pile of rubble in the shape of a rotating top, and is made up of rocks bound together by gravity. It is about a third of a mile (500 metres) wide.
“If Bennu is completely full, that would imply almost solid rock, but we found a lot of vacuum at the surface,” said study co-author Kevin Walsh, a member of the OSIRIS-REx science team from the Southwest Research Institute in Boulder, Colorado. . , in the current situation.
So what would have happened if the spacecraft’s thrusters hadn’t fired right away?
Study co-author Patrick Michel, a scientist at OSIRIS-REx and director of research at the National Center for Scientific Research at the Côte d’Azur Observatory in Nice, France, said.
Fortunately, the spacecraft and its precious sample are headed back to Earth. The Bennu sample is scheduled to land in September 2023.
When the spacecraft arrived at Bennu in December 2018, the OSIRIS-REx team was surprised to discover that the asteroid’s surface was covered in rock. Previous observations had prepared them for sandy, beach-like terrain.
Scientists also witnessed particles from the asteroid being launched into space.
“Our predictions about the asteroid’s surface were completely wrong,” study author Dante Loretta, OSIRIS-Rex principal investigator at the University of Arizona, Tucson, said in a statement.
The spacecraft took pictures of the site where it collected a sample from Bennu, further baffling the team. Although Osiris Rex gently bugged the asteroid, it dumped a massive amount of rock debris and left a 26-foot (8 m) wide crater.
“What we saw was a huge wall of debris radiating from the sample site,” said Loretta, a professor of planetary science and cosmic chemistry at the University of Arizona’s Lunar and Planetary Laboratory. We were like, ‘Holy cow! “Every time we tested the sample capture procedure in the lab, we hardly made an opening.”
Photos before and after the landing site show the exciting difference. The images reveal what appears to be a depression in the surface, with several large boulders at its base. The sampling event itself likely caused this sunken landform. The asteroid’s dark surface also contains reflective dust near the collection point, showing where rocks were transported during the event. These changes are visible in the slider below.
Analyzing the spacecraft’s acceleration data, the team determined that it encountered very little resistance, the same amount that someone might feel pressing the piston in a French coffee machine.
Understanding more about Bennu’s formation could help scientists study other asteroids, whether the goal is planning missions like OSIRIS-REx or protecting Earth from potential collisions with space rocks.
An asteroid like Bennu, barely tying itself together, could break through the Earth’s atmosphere, which could pose other risks even if it wasn’t a direct hit.
“We need to continue to have physical interaction with those bodies because that’s really the only way to determine their mechanical properties and their response to external actions,” Michel said. “The images are important but they don’t give us an answer as to whether they are weak or strong.”
OSIRIS-REx — which stands for Origins, Spectral Interpretation, Resource Identification, and Security-Regolith Explorer — was the first NASA mission to be sent to a near-Earth asteroid, and once there it performed the closest orbit of a planetary object by spacecraft to date. Bennu is the smallest object a spacecraft has ever orbited.
The Bennu spacecraft memorial is the largest sample collected by a NASA mission since Apollo astronauts returned the lunar rocks.
Once Osiris Rex approaches Earth in 2023, it will dump the capsule containing the sample, which will shoot through Earth’s atmosphere and parachute into the Utah desert.
If OSIRIS-REx is still healthy after it falls from the sample, it will then start a new expedition to study other asteroids.
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