Asteroid Bennu Nearly Swallowed Up NASA's Sampling Spacecraft

In October 2020, the agency's OSIRIS-REx spacecraft nearly sank into the surface of the rubbly asteroid while picking up rocks for shipment to Earth in 2023, team members revealed Thursday (July 7). The spacecraft only escaped getting stuck or sinking into oblivion within Bennu by firing its thrusters at the right moment. Space.com reports: "We expected the surface to be pretty rigid," principal investigator Dante Lauretta, a planetary scientist at the University of Arizona, told Space.com. "We saw a giant wall of debris flying away from the sample site. For spacecraft operators, it was really frightening." Now that the spacecraft (more formally known as Origins, Spectral Interpretation, Resource Identification, Security-Regolith Explorer) is safely on its way back to our planet to deliver its precious cargo, scientists are digging into the science implications of the dramatic moment.

"It turns out that the particles making up Bennu's exterior are so loosely packed and lightly bound to each other that they act more like a fluid than a solid," Lauretta said in a University of Arizona statement. That 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 against each other like plastic balls in a children's play area, has implications for how asteroids were formed and also for planetary defense techniques to protect against potential rogue space rocks coming near our planet, NASA added in a second statement.

Meteorite

[phantomfive]

I was asking myself why we haven't seen any meteorites that landed with this type of composition, but then I realized any astroid that hits earth with this type of composition would probably disintegrate before landing.

Re:Meteorite

[ShanghaiBill]

any astroid that hits earth with this type of composition would probably disintegrate before landing.

Most asteroids that hit Earth disintegrate in the atmosphere. They are either BPORs or held together by ice that vaporizes.

BPOR = Big Pile of Rubble

Re:Meteorite

[NoWayNoShapeNoForm]

any astroid that hits earth with this type of composition would probably disintegrate before landing.

Most asteroids that hit Earth disintegrate in the atmosphere. They are either BPORs or held together by ice that vaporizes.

BPOR = Big Pile of Rubble

So even way back when...the primordial Universe suffered from shoddy building standards? /sarcasm

Re:

[GoTeam]

I blame antimatter for not doing its job...

Re:

[phantomfive]

I would mod you up if I had points

At the right moment? Yeah, right.

[mveloso]

They make it sound so Hollywood.

In reality, if it required "the right moment" the spacecraft would still be stuck on the asteroid.

Easier to mine?

[RitchCraft]

Knowing that the composition of asteroids like Bennu are so loosely packed should make mining them easier perhaps? Maybe a giant net that surrounds them and then hoover up the debris. Of course there would be the risk of creating tens of thousands of little asteroids flying off in all directions if the netting operation was not successful. Asteroid mining is going to happen eventually so these first missions to asteroids are a crucial step in understanding them.

Re:

[ChatHuant]

Maybe a giant net that surrounds them and then hoover up the debris.

Well, if the whole exercise ends up with the invention of a hoover that works in a vacuum, I'll be very happy - whether it can be used for mining or not...

Re:

[RitchCraft]

LOL, yeah, poor choice of words there. A vacuum in a vacuum. Doh!

But

[drinkypoo]

They know the surface of the asteroid was like that.

But they don't know how much of it was.

So it's of interest but ultimately not all that useful in "planetary defense techniques to protect against potential rogue space rocks coming near our planet" — which is in fact not how anything works.

Rubble piles are the most dangerous.

[Eunomion]

Something very solid and cohesive, you can deflect it with reasonable confidence. And something with a lot of porous, volatile material like a comet nucleus, that might be even easier since you could theoretically use its own surface material as propellant in the deflection. But it would be much more complicated to do anything with a pile of rocky rubble. Most of the energy from deflection could just be absorbed in vibration and rotation, while blowing it up turns it into a shotgun blast. You'd have to

Re:

[OrangeTide]

if the particles are fine enough you may be able to give them a static charge so they repel each other. The sun's radiation might already do some of the work charging surface particles for you. Perhaps with the right powerful field set up on the surface you could disperse a significant portion of dust from an asteroid. But maybe eventually you'd end up just having a cloud around your field generator and it wouldn't work quite as efficiently.

Strategy

[DriveDog]

"...implications for how asteroids were formed and also for planetary defense techniques to protect against potential rogue space rocks coming near our planet"
Giant pressure washer. Blast it apart while pushing it.