In October 2020, a small spacecraft briefly touched down on an asteroid to snag a chunk of it to convey to Earth. Almost two years later, scientists have realized that if the OSIRIS-REx spacecraft had prolonged its keep even a tiny bit longer, it might have sunk proper into the asteroid.

That’s as a result of asteroid Bennu is nothing like scientists had predicted. Rather than being a strong, flying rock, Bennu is definitely made up of small, pebble-like particles that aren’t strongly sure collectively, creating numerous house on its floor. It’s most corresponding to a plastic ball pit, NASA writes in a brand new release. “Our expectations about the asteroid’s surface were completely wrong” Dante Lauretta, principal investigator of OSIRIS-REx and lead writer of a latest paper detailing the findings, mentioned within the launch.

OSIRIS-REx arrived on the asteroid in December 2018 with a mission to retrieve a pattern from Bennu and carry it to Earth for evaluation. The spacecraft touched down on Bennu in October 2020, extending its robotic arm to scoop up a chunk of the asteroid. OSIRIS-REx then instantly fired up its thrusters to again away from Bennu. The spacecraft’s sampling head touched Bennu’s floor for about 6 seconds earlier than retreating. By stirring up among the mud and pebbles on the asteroid, OSIRIS-REx was capable of seize a pair ounces of fabric.

The temporary rendezvous left fairly an impression on Bennu, leading to a chaotic explosion of pebbles and a crater 26 ft (8 meters) extensive. “Every time we tested the sample pickup procedure in the lab, we barely made a divot,” Lauretta mentioned. But after reviewing the footage from the actual pattern pick-up, the scientists have been left confused. “What we saw was a huge wall of debris radiating out from the sample site,” Lauretta mentioned. “We were like, ‘Holy cow!’”

After analyzing the quantity of particles seen in before-and-after photos of the touchdown website, the scientists realized that OSIRIS-REx confronted as a lot resistance from touching down on the asteroid as “a person would feel while squeezing the plunger on a French press coffee carafe,” NASA wrote in a statement. That is to say, the spacecraft met little or no resistance, actually not the kind of resistance one would anticipate from touchdown on a rocky physique. As the spacecraft fired its thrusters to depart, it was sinking into the asteroid.

“If Bennu was completely packed, that would imply nearly solid rock, but we found a lot of void space in the surface,” Kevin Walsh, a member of the OSIRIS-REx science workforce and lead writer of a second paper on Bennu’s composition, mentioned in an announcement.

When OSIRIS-REx first arrived on the asteroid, closeup photos of Bennu revealed that its floor was crammed with boulders, fairly than the sleek sandy floor that had been predicted. The photos additionally confirmed that Bennu was spitting out pebbles into house. “I think we’re still at the beginning of understanding what these bodies are, because they behave in very counterintuitive ways,” Patrick Michel, an OSIRIS-REx scientist, mentioned within the NASA launch.

Bennu has been stuffed with surprises. One of the primary was its odd form, just like a child’s spinning top.