NASA’s asteroid-sampling spacecraft had a near-death experience at Bennu, according to the mission team.
In October 2020, the agency’s OSIRIS-REx spacecraft nearly sank into the asteroid’s surface in rubble while picking up rocks to ship to Earth in 2023, team members revealed Thursday, July 7. . The spaceship only escaped being stuck or oblivion within Bennu by firing its thrusters at the right time.
“We expected the surface to be quite stiff,” lead researcher Dante Lauretta, a planetary scientist at the University of Arizona, told Space.com. “We saw a giant wall of debris moving away from the sample site. For spacecraft operators, that was really scary.”
Read more: Dramatic Sampling Shows Asteroid Bennu Has Nothing To Do With Scientists’ Expectations
Related: Mount a shotgun with NASA’s OSIRIS-REx asteroid probe as it buzzes Bennu (video)
Now that the spacecraft (more formally known as origins, spectral interpretation, resource identification, safety-regolith explorer) is on its way back safely to our planet to deliver its precious cargo, scientists are studying the scientific implications of this dramatic moment.
“It turns out that the particles that make up Bennu’s exterior are so loose and loosely bound together that they act more like a fluid than a solid,” Lauretta said in a statement from the University of arizona. (opens in a new tab).
This structure is why the OSIRIS-REx sampling probe had such a close call, he and his colleagues determined. The loose surface, made up of particles jostling like plastic balls in a children’s playground, has implications for how asteroids formed and also for planetary defense techniques to protect against rogue space rocks potential approaching our planet, NASA added in a second statement (opens in a new tab).
Photographs from the mission showed a giraffe-sized crater left by the brief touchdown, scarring the surface up to 26 feet (8 meters) wide. It had nothing to do with the little divot investigators predicted from simulations.
The encounter was a very close call for the spacecraft, mission personnel now say. Where the scientists expected to find a firm surface, the spacecraft experienced resistance comparable to that needed to strain a French press, they said.
“At the time we fired our thrusters to leave the surface, we were still plunging into the asteroid,” said Ron Ballouz, an OSIRIS-REx scientist based at Johns Hopkins Applied Physics Laboratory in Maryland, in the statement from the University of Arizona.
“I think we’re still at the beginning of understanding what these bodies are, because they behave in very counter-intuitive ways,” said OSIRIS-REx team member and asteroid scientist Patrick Michel. the Côte d’Azur Observatory in France. Statement from NASA.
Space.com Senior Writer Tereza Pultarova contributed reporting for this story. Follow Elizabeth Howell on Twitter @howellspace (opens in a new tab). Follow us on twitter @Spacedotcom (opens in a new tab) and on Facebook (opens in a new tab).