" "

Asteroid Bennu nearly ate NASA’s sampling spacecraft

NASA’s asteroid sampling spacecraft had a near-death experience in Bennu, according to the mission team.

In October 2020, the agency’s OSIRIS-REx spacecraft almost sank into the surface of the shattered asteroid while picking up rocks for transport to Earth in 2023, team members said on Thursday (July 7). The starship only escaped by getting stuck in Bennu or falling into oblivion by firing its thrusters at the right moment.

“We expected the surface to be quite rigid,” lead researcher Dante Lauretta, a planetary scientist at the University of Arizona, told Space.com. “We saw a huge wall of debris flying away from the sample site. For spacecraft operators, that was really scary.”

Continue reading: Dramatic sampling shows asteroid Bennu is not meeting scientists’ expectations
: Ride NASA’s OSIRIS-REx Asteroid Probe While It Hums Bennu (Video)

Now that the spacecraft (formerly known as Origins, Spectral Interpretation, Resource Identification, Security-Regolith Explorer) is safely en route back to our planet to deliver its precious cargo, scientists are studying the scientific implications of the dramatic moment.

“It turns out that the particles that make up Bennu’s exterior are so loosely packed and lightly bound together that they appear more like a liquid than a solid,” Lauretta said in a statement from the University of Arizona (opens in new tab).

This structure is why the OSIRIS-REx sampling probe came so close, he and his colleagues found. The loose surface, made up of particles jostling against each other like plastic balls in a children’s play area, has implications for asteroid formation and also planetary defense techniques to protect against potential space villains approaching our planet, NASA added in a added second statement (opens in new tab).

Photos from the mission showed a giraffe-sized crater left by the short landing, scarring the surface up to 8 meters wide. This was nothing like the little divot investigators predicted by simulations.

The encounter was very close for the spacecraft, mission officials now say. Where scientists had expected to find a solid surface, the spacecraft experienced drag comparable to that required to filter a French coffee maker, they said.

“When we fired our thrusters to leave the surface, we still crashed into the asteroid,” said Ron Ballouz, an OSIRIS-REx scientist at the Johns Hopkins Applied Physics Laboratory in Maryland, in the University of Arizona statement.

“I think we’re just beginning to understand these bodies because they’re behaving very counterintuitively,” Patrick Michel, a member of the OSIRIS-REx team and an asteroid scientist at France’s Côte d’Azur Observatory, said in a NASA statement.

Space.com senior writer Tereza Pultarova contributed to this story. Follow Elizabeth Howell on Twitter @howellspace (opens in new tab). Follow us on Twitter @spacedotcom (opens in new tab) and further Facebook (opens in new tab).