APOD: Tagging Bennu (2023 Sep 21)

[APOD Robot]

Tagging Bennu

Explanation: The OSIRIS-REx spacecraft's arm reached out and touched asteroid 101955 Bennu on October 20, 2020, after a careful approach to the small, near-Earth asteroid's boulder-strewn surface. Dubbed a Touch-And-Go (TAG) sampling event, the 30 centimeter wide sampling head (TAGSAM) appears to crush some of the rocks in this close-up recorded by the spacecraft's SamCam. The image was snapped just after surface contact some 321 million kilometers from planet Earth. One second later, the spacecraft fired nitrogen gas from a bottle intended to blow a substantial amount of Bennu's regolith into the sampling head, collecting the loose surface material. And now, nearly three years later, on Sunday, September 24, that sample of asteroid Bennu is scheduled to arrive on planet Earth. The sample return capsule will be dropped off by the OSIRIS-Rex spacecraft as it makes a close flyby of Earth. Twenty minutes after the drop-off, the spacecraft will fire its thrusters to divert past Earth and continue on to orbit near-Earth asteroid 99942 Apophis.

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[RocketRon]

Its going to be fascinating to see what this stuff consists of ?

Was this the raw material that the solar system was made of.
Or, stuff from a shattered planet, the cause(s) of which we can only guess at.

Answers on the back of a postage stamp. ?
Or in a long drawn out series of articles on the analysis of it all.
Much research to be done, we are guessing ...

[alex555]

It looks like a shortbread cookie.

[Chris Peterson]

Its going to be fascinating to see what this stuff consists of ?

Was this the raw material that the solar system was made of.
Or, stuff from a shattered planet, the cause(s) of which we can only guess at.

Answers on the back of a postage stamp. ?
Or in a long drawn out series of articles on the analysis of it all.
Much research to be done, we are guessing ...

This is a C-type asteroid, so we know that it is made up of the primitive earliest material forming the Solar System. The selection of a carbonaceous asteroid was based on obtaining good samples of such material unaltered by passage through the atmosphere in the form of meteorites.

FWIW, there is no evidence that any planets were ever shattered and formed debris in the Solar System. The largest bodies that collided and created asteroids were at most a few hundred kilometers in diameter.

[Roy]

I wish Tom Van Flandern were still alive to see these pictures! His “exploded planet” hypothesis for the asteroids looks better and better, with shattered rock and gravel. When they get the samples back we’ll know for sure.

[Chris Peterson]

I wish Tom Van Flandern were still alive to see these pictures! His “exploded planet” hypothesis for the asteroids looks better and better, with shattered rock and gravel. When they get the samples back we’ll know for sure.

We already know. There are no "exploded planets". It is a ridiculous idea. We actually have a pretty good model for the formation of the different classes of asteroids, and it doesn't involve the breakdown (or breakup) of planet-sized bodies.

[johnnydeep]

I wish Tom Van Flandern were still alive to see these pictures! His “exploded planet” hypothesis for the asteroids looks better and better, with shattered rock and gravel. When they get the samples back we’ll know for sure.

We already know. There are no "exploded planets". It is a ridiculous idea. We actually have a pretty good model for the formation of the different classes of asteroids, and it doesn't involve the breakdown (or breakup) of planet-sized bodies.

What about the collision event 4.5 By ago that is hypothesized to have occurred between the nascent Earth and the now defunct planet Theia? In addition to creating the Earth's Moon, could any of the other debris have escaped to the asteroid belt?

[Chris Peterson]

I wish Tom Van Flandern were still alive to see these pictures! His “exploded planet” hypothesis for the asteroids looks better and better, with shattered rock and gravel. When they get the samples back we’ll know for sure.

We already know. There are no "exploded planets". It is a ridiculous idea. We actually have a pretty good model for the formation of the different classes of asteroids, and it doesn't involve the breakdown (or breakup) of planet-sized bodies.

What about the collision event 4.5 By ago that is hypothesized to have occurred between the nascent Earth and the now defunct planet Theia? In addition to creating the Earth's Moon, could any of the other debris have escaped to the asteroid belt?

No. Any debris that failed to re-aggregate from very early collisions would have long since fallen into the Sun, or been ejected from the Solar System entirely. The asteroid belt is formed from material in the protoplanetary disk that failed to aggregate into a planet due to orbital resonances created by Jupiter. We have many samples of material from there that inform us about the different formation histories of different asteroid classes.

[johnnydeep]

We already know. There are no "exploded planets". It is a ridiculous idea. We actually have a pretty good model for the formation of the different classes of asteroids, and it doesn't involve the breakdown (or breakup) of planet-sized bodies.

What about the collision event 4.5 By ago that is hypothesized to have occurred between the nascent Earth and the now defunct planet Theia? In addition to creating the Earth's Moon, could any of the other debris have escaped to the asteroid belt?

No. Any debris that failed to re-aggregate from very early collisions would have long since fallen into the Sun, or been ejected from the Solar System entirely. The asteroid belt is formed from material in the protoplanetary disk that failed to aggregate into a planet due to orbital resonances created by Jupiter. We have many samples of material from there that inform us about the different formation histories of different asteroid classes.

[Pastorian]

The wow factor for me is the precision with which OSIRIS-REx is operating, namely tagging an asteroid as opposed to crashing into it (crashing = less precise), then dropping off of payload and redeploying to another asteroid. It would seem space missions have squarely moved from the one-and-done model to multipurpose and reuse.

[johnnydeep]

The wow factor for me is the precision with which OSIRIS-REx is operating, namely tagging an asteroid as opposed to crashing into it (crashing = less precise), then dropping off of payload and redeploying to another asteroid. It would seem space missions have squarely moved from the one-and-done model to multipurpose and reuse.

Yes, NASA accomplishes some pretty amazing feats of precision flying and engineering. And not only are the mission craft being repurposed for further missions - some not even intended at the outset - but so too are the launch vehicles being reused rather than discarded. I'm looking at you SpaceX!

[orin stepanek]

Amazing what Science can do!

[RocketRon]

A Space.com article on this reports that the rubble on Bennu is so loosely packed that the probe was almost "swallowed up'
and it was only the use of thrusters that prevented this. !!
And, the probes visit left a rather large gash in the surface of Bennu.

The wow factor for me is the precision with which OSIRIS-REx is operating, namely tagging an asteroid as opposed to crashing into it (crashing = less precise),

Which begs the question about where did all this rubble come from then ?
A previous Solar System for a previous Sun, that has gone to that great heaven in the sky. ???
Hmmm, even that epithet needs work ....

Much research ahead, we think

[Chris Peterson]

A Space.com article on this reports that the rubble on Bennu is so loosely packed that the probe was almost "swallowed up'
and it was only the use of thrusters that prevented this. !!
And, the probes visit left a rather large gash in the surface of Bennu.

The wow factor for me is the precision with which OSIRIS-REx is operating, namely tagging an asteroid as opposed to crashing into it (crashing = less precise),

Which begs the question about where did all this rubble come from then ?
A previous Solar System for a previous Sun, that has gone to that great heaven in the sky. ???
Hmmm, even that epithet needs work ....

Much research ahead, we think

This is the earliest material that accreted out of the molecular cloud that condensed into the Sun and our planetary system. Its development is traced by looking at the form of a number of different constituents, particularly olivine. Almost everything formed in place around the Sun, but we do find tiny particles that are extrasolar... material that originated in the supernova or supernovas that created the raw materials of our system, and which has survived largely unaltered. From this material we can learn a lot about the origin of that material.

[RocketRon]

This is the earliest material that accreted out of the molecular cloud that condensed into the Sun and our planetary system. Its development is traced by looking at the form of a number of different constituents, particularly olivine. Almost everything formed in place around the Sun, but we do find tiny particles that are extrasolar... material that originated in the supernova or supernovas that created the raw materials of our system, and which has survived largely unaltered. From this material we can learn a lot about the origin of that material.

There is more to it than that though ?

One of the carbonaceous chondrite meteorites that was recovered contained something like 15 amino acids
- "and smelled like/of alcohols" !. And contained varieties of silicon carbides, older than the Solar System.
These didn't form in the sun, but MUST be part of some previous planet-like system ?
So the picture is way more complex. ???

https://en.wikipedia.org/wiki/Murchison_meteorite

[RocketRon]

What NASA are hunting here, unsaid, is that there was life here BEFORE the present Solar System.
That will set the cat among the pigeons ...

[Chris Peterson]

This is the earliest material that accreted out of the molecular cloud that condensed into the Sun and our planetary system. Its development is traced by looking at the form of a number of different constituents, particularly olivine. Almost everything formed in place around the Sun, but we do find tiny particles that are extrasolar... material that originated in the supernova or supernovas that created the raw materials of our system, and which has survived largely unaltered. From this material we can learn a lot about the origin of that material.

There is more to it than that though ?

One of the carbonaceous chondrite meteorites that was recovered contained something like 15 amino acids
- "and smelled like/of alcohols" !. And contained varieties of silicon carbides, older than the Solar System.
These didn't form in the sun, but MUST be part of some previous planet-like system ?
So the picture is way more complex. ???

https://en.wikipedia.org/wiki/Murchison_meteorite

There is no more to it than that. These bodies have gone through a long formation process, involving accretion, shocks, existence in magma oceans (early bodies had molten surfaces from impacts and/or molten interiors from the decay of Al-26. They subsequently went through aqueous mineral formation processes. All of this history is preserved in various mineral structures. There was plenty of opportunity in all of this for complex organic chemical reactions like those which create amino acids. There is no reason to think that the amino acids which have been observed originated anywhere but in our own system in the first few million years of its formation, and possibly long after on some surfaces.

The only thing older than our solar system are the presolar particles I already mentioned, which are a very, very tiny fraction of carbonaceous material.

[RocketRon]

If silicon carbides have been tentatively dated at ~7.5 billion years (??), that is difficult to reconcile with 'our' solar System ??
(And still quite some time post the formation of the Universe, so must have had a life/lives before that ?)

[Chris Peterson]

If silicon carbides have been tentatively dated at ~7.5 billion years (??), that is difficult to reconcile with 'our' solar System ??
(And still quite some time post the formation of the Universe, so must have had a life/lives before that ?)

Read what I wrote.

[RocketRon]

Remind us again precisely what you said about silicon carbide - & PRECEDING the age of our Solar System ???

[RocketRon]

It goes without saying of course that ALL the matter in our solar system is recycled 'star dust'.

Perhaps we are merely discussing to what extent it has truly been recycled ?
And whether that can actually be distinguished ...

[Chris Peterson]

It goes without saying of course that ALL the matter in our solar system is recycled 'star dust'.

Perhaps we are merely discussing to what extent it has truly been recycled ?
And whether that can actually be distinguished ...

It is easily distinguished. Presolar grains, which make up a fraction of a percent of carbonaceous material, are largely unaltered grains of the molecular dust cloud from which the Solar System formed. They are very refractory dust particles. Everything else is highly altered- melted, shocked, subjected to aqueous reactions. Material that formed here and no longer resembles the original dust except in gross elemental percentages. These things are readily determined by looking at isotope ratios.

[Ann]

It goes without saying of course that ALL the matter in our solar system is recycled 'star dust'.

Perhaps we are merely discussing to what extent it has truly been recycled ?
And whether that can actually be distinguished ...

It is easily distinguished. Presolar grains, which make up a fraction of a percent of carbonaceous material, are largely unaltered grains of the molecular dust cloud from which the Solar System formed. They are very refractory dust particles. Everything else is highly altered- melted, shocked, subjected to aqueous reactions. Material that formed here and no longer resembles the original dust except in gross elemental percentages. These things are readily determined by looking at isotope ratios.

Thanks, Chris. That's illuminating.

Ann

[johnnydeep]

It goes without saying of course that ALL the matter in our solar system is recycled 'star dust'.

Perhaps we are merely discussing to what extent it has truly been recycled ?
And whether that can actually be distinguished ...

It is easily distinguished. Presolar grains, which make up a fraction of a percent of carbonaceous material, are largely unaltered grains of the molecular dust cloud from which the Solar System formed. They are very refractory dust particles. Everything else is highly altered- melted, shocked, subjected to aqueous reactions. Material that formed here and no longer resembles the original dust except in gross elemental percentages. These things are readily determined by looking at isotope ratios.

Are those "unaltered grains" composed of a small number of types of molecules/minerals/etc., or is there wide variation?

[Chris Peterson]

It goes without saying of course that ALL the matter in our solar system is recycled 'star dust'.

Perhaps we are merely discussing to what extent it has truly been recycled ?
And whether that can actually be distinguished ...

It is easily distinguished. Presolar grains, which make up a fraction of a percent of carbonaceous material, are largely unaltered grains of the molecular dust cloud from which the Solar System formed. They are very refractory dust particles. Everything else is highly altered- melted, shocked, subjected to aqueous reactions. Material that formed here and no longer resembles the original dust except in gross elemental percentages. These things are readily determined by looking at isotope ratios.

Are those "unaltered grains" composed of a small number of types of molecules/minerals/etc., or is there wide variation?

Quite a few mineral species have been identified- diamond, silicon carbide (and a number of others that you might recognize from applications like drill bits and sandpaper), olivine. They range in size from a few thousand atoms to micron scale. They are found embedded in the matrix of altered material that makes up many asteroids (primarily observed from carbonaceous meteorites).