“The surface was smooth and flowed like a fluid.”
The original mission for NASA’s OSIRIS-REx spacecraft was to fly to asteroid Bennu, where it was supposed to briefly land on the body’s presumably rocky surface, collect a small sample, and return home.
But while most of the mission miraculously went according to plan, there was one major surprise along the way.
When OSIRIS-REx attempted to land on Bennu in 2020, it surprisingly sank into the asteroid’s quicksand-like surface – compared to a children’s ‘plastic ball pit’ in a new update. NASA day – triggering a searing explosion of celestial matter.
Now mission researchers finally think they know why, as detailed in a pair of new papers published this week.
“We expected the surface to be quite stiff, a bit like landing on a pile of gravel: some dust flying off and some particles jumping out,” Dante Lauretta, lead author of one of the studies and principal investigator of the OSIRIS-RE mission, told Space.com. “But as we brought the footage back after the event, we were stunned.”
“There was clearly no resistance,” she added. “The surface was smooth and flowed like a fluid.”
The result was so surprising, in fact, that the researchers returned the craft to Bennu six months later. Images collected during the second mission showed that OSIRIS-REx had left a 65-foot-wide impact crater, dubbed “Nightingale”, in its wake.
According to a statement from NASA, researchers believe that the secret to Bennu’s unexpected fluff lies in his mass. The particles that form the planet’s surface are both loose and loosely bound, which means that although they appear solid, there is actually a lot of empty space.
As a result, NASA says walking the planet would apparently feel like “entering a pit of plastic bullets.” Yes, like those at your local Chuck E. Cheese.
The research is exciting, although frankly, it’s also a little scary. Since Bennu is held together by so little force, an impact with Earth would likely blast the asteroid into our Pale Blue Dot’s atmosphere, the researchers say – a very different kind of hazard than colliding with a hard celestial body.
READ MORE: Dramatic Sampling Shows Asteroid Bennu Is Nothing Like Scientists Expected [Space.org]
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