Near-Earth asteroid has a plastic ball pit surface

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According to NASA scientists, a near-Earth asteroid named Bennu is full of surprises—the latest of which is the fact that its surface resembles a crater of plastic balls.

The new disclosure comes after the space agency Successfully collected a sample from the asteroid in October 2020,

During the historic collection program, the sample head of the OSIRIS-REx spacecraft sank 1.6 feet (0.5 m) into the asteroid’s surface. Apparently, Bennu’s exterior is made up of loosely packed particles that aren’t very securely bound together, which is based on whether the spacecraft collected a sample. if the spacecraft Had it not thrown its thruster backwards after its quick collection of dust and rocks, it may have sunk directly into the asteroid.

“By the time we fired our thrusters to leave the surface, we were sinking into the asteroid,” Ron Ballouz, OSIRIS-REx scientist based at the Johns Hopkins Applied Physics Laboratory in Laurel, Maryland, said in a statement. Balluz is a co-author of a pair of July studies released in the journals science And science advance about search.

Bennu is a rubble pile-shaped asteroid shaped like a spinning top, composed of rocks bound together by gravity. It is about a third of a mile (500 m) wide.

Study co-author Kevin Walsh, a member of the OSIRIS-REx science team at the Southwest Research Institute in Boulder, Colorado, said, “If Bennu were completely packed, it would mean a nearly solid rock, but we don’t see a difference in the surface. Got too much free space.” , in a statement.

So what could happen if the spacecraft’s thrusters didn’t fire immediately?

“It may be that OSIRIS-REx went deep inside the asteroid, which is both fascinating and scary,” said study co-author Patrick Mitchell, an OSIRIS-REx scientist and researcher at the Center National de la Recherche Scientific in Cte d’Or. said the director. ‘Azur Observatory in Nice, France.

Fortunately, the spacecraft and its prized specimens are headed back to Earth. Bennu’s sample Due to land in September 2023,

When the spacecraft reached Bennu in December 2018, the OSIRIS-REx team was surprised to find that the asteroid’s surface was covered with boulders. Previous observations had drawn them to sandy, beach-like terrain.

Scientists also observed the release of asteroid particles into space.

This image shows asteroid Bennu ejecting rock particles from its surface on January 19, 2019.

“Our expectations about the asteroid’s surface were completely wrong,” said study author Dante Lauretta, OSIRIS-REx principal investigator at the University of Arizona, Tucson, in a statement.

The spacecraft captured images of the site where it collected a sample from Bennu, which further baffled the team. Although OSIRIS-REx tapped the asteroid very slowly, it kicked up a massive amount of rocky debris and left a crater 26 feet (8 m) wide.

“What we saw was a giant wall of debris emanating from the sampling site,” said Loretta, a Regents professor of planetary science and cosmochemistry at the University of Arizona’s Lunar and Planetary Laboratory. “We were like, ‘Holy cow!’ Every time we tested the sample taking process in the lab, we barely made a divot.”

Before and after photos of the touchdown site show the dramatic difference. The images show what looks like a depression in the surface, with several large boulders at the base. The sampling event itself caused this sunken landform. The asteroid’s dark surface also contains more reflective dust near the collection point, showing where the rocks were moved during the event. These changes are clearly visible in the slider below.


University of Arizona / Goddard / NASA

When analyzing the spacecraft’s acceleration data, the team determined that it encountered very little resistance, about the same amount that someone might feel pushing aboard a French press coffee maker.

Understanding more about Bennu’s composition could help scientists study other asteroids, whether the goal is to plan missions such as OSIRIS-REx or to protect Earth from potential collisions with space rocks.

An asteroid like Bennu, which is barely holding itself together, could break into Earth’s atmosphere, posing other risks, even if not a direct hit.

“We need to keep interacting with those bodies physically because this is the only way to really determine their mechanical properties and response to external actions,” Mitchell said. “Images are important but don’t tell us whether they are weak or strong.”

OSIRIS-REx – which stands for Origin, Spectral Interpretation, Resource Identification, Security – Regolith Explorer – was NASA’s first mission to a near-Earth asteroid, and once there the closest approach to a planetary body by a spacecraft. Class performance. , Bennu is the smallest object ever orbited by a spacecraft.

The spacecraft souvenir from Bennu is the largest specimen collected by a NASA mission since lunar rocks were brought back by Apollo astronauts.

Once OSIRIS-REx approaches Earth in 2023, it will lift off the sampling capsule, which will pass through Earth’s atmosphere and parachute down into the Utah desert.

If OSIRIS-REx is still in good health after dropping the sample, it will embark on a new campaign to study other asteroids.

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