Starship Asterisk*

by **Chris Peterson** » Tue Sep 26, 2023 4:42 am

Galaxian wrote: ↑Tue Sep 26, 2023 3:05 am
Chris Peterson wrote: ↑Thu Sep 21, 2023 1:28 pm 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.
Yeah, but now we have a pure, uncontaminated blob of Original Stuff that hasn't been cooked by passage through our air nor slimed by all of the bugs our air and ground are full of.

That is an amazing achievement.

Chris Peterson wrote: ↑Thu Sep 21, 2023 1:28 pm 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.
I find that problematic.

Earth is supposed to have been smacked by A Giant Impactor a while back and the result is supposed to be our lovely little Moon. One Moon. No others. Not even tiny, littly bits. The odds of absolutely everything falling back to the Earth or merging into Luna don't seem very high.

But that's only intuition. I don't have a supercomputer to model this on so maybe I'm being simplistic and wrong?

However: yet another Giant Impactor is sometimes blamed for "tipping" Uranus and her satellites. This one, too, left nothing behind. That, too, seems unlikely.

Venus rotating "backwards"? Oh, yes, yet another Giant Impactor. Why Venus has nothing even resembling a Phobos as a moon after the Giant Impact is a mild mystery.

My tea getting cold? That, too, must be a Giant Impactor.

Still, at least we now have good Science telling us that only Little Impactors such as Bennu are likely to hit us any time soon and even Bennu isn't very likely.

Unless Osiris tapped it hard enough to alter its orbit a bit?

After DART, that would be rather ironic. :)

To the extent that giant impacts occurred, they were very, very early in the formation of the Solar System. And giant impacts are most likely to produce gravitationally bound debris (as with the Earth/Moon), meaning that material doesn't escape to other parts of the Solar System. And residual material would not be in stable orbits, so it would have long since vanished into the Sun.

So no... we have no reason to think that any significant amount of debris in the Solar System is the product of planet-scale collisions.

by **Galaxian** » Tue Sep 26, 2023 3:13 am

Ann wrote: ↑Mon Sep 25, 2023 3:55 am I didn't comment on this picture before because, well, it's not my kind of picture. But the mission itself is certainly impressive.

Now the sample return capsule carrying rocks and gravel from Bennu has returned to the Earth! And the rest of the spacecraft is on its way to another asteroid to continue its mission to find out more about asteroids in the Earth's vicinity. I must applaud NASA!

Ann

Definitely!

It's an achievement the entire species should be proud of!

And something I never thought would ever happen. But then, I never expected to get close-ups of Pluto and Charon, nor images of planets not in our Solar System, nor evidence of thousands of exoworlds.

Astro-stuff certainly has progressed a bit since I was reading Hugh Walters oh so many years ago.

Those people are amazing!

by **Galaxian** » Tue Sep 26, 2023 3:05 am

Chris Peterson wrote: ↑Thu Sep 21, 2023 1:28 pm 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.

Yeah, but now we have a pure, uncontaminated blob of Original Stuff that hasn't been cooked by passage through our air nor slimed by all of the bugs our air and ground are full of.

That is an amazing achievement.

Chris Peterson wrote: ↑Thu Sep 21, 2023 1:28 pm 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.

I find that problematic.

Earth is supposed to have been smacked by A Giant Impactor a while back and the result is supposed to be our lovely little Moon. One Moon. No others. Not even tiny, littly bits. The odds of absolutely everything falling back to the Earth or merging into Luna don't seem very high.

But that's only intuition. I don't have a supercomputer to model this on so maybe I'm being simplistic and wrong?

However: yet another Giant Impactor is sometimes blamed for "tipping" Uranus and her satellites. This one, too, left nothing behind. That, too, seems unlikely.

Venus rotating "backwards"? Oh, yes, yet another Giant Impactor. Why Venus has nothing even resembling a Phobos as a moon after the Giant Impact is a mild mystery.

My tea getting cold? That, too, must be a Giant Impactor.

Still, at least we now have good Science telling us that only Little Impactors such as Bennu are likely to hit us any time soon and even Bennu isn't very likely.

Unless Osiris tapped it hard enough to alter its orbit a bit?

After DART, that would be rather ironic.

by **Ann** » Mon Sep 25, 2023 3:55 am

I didn't comment on this picture before because, well, it's not my kind of picture. But the mission itself is certainly impressive.

Now the sample return capsule carrying rocks and gravel from Bennu has returned to the Earth! And the rest of the spacecraft is on its way to another asteroid to continue its mission to find out more about asteroids in the Earth's vicinity. I must applaud NASA!

Ann

by **johnnydeep** » Fri Sep 22, 2023 2:22 pm

Chris Peterson wrote: ↑Fri Sep 22, 2023 2:17 pm
johnnydeep wrote: ↑Fri Sep 22, 2023 2:09 pm
Chris Peterson wrote: ↑Fri Sep 22, 2023 1:38 pm
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).
Thanks. And just to stick a pin in this point, those particular minerals are such that they couldn't possibly have been formed by any of the known processes going on in the still-forming solar system (high speed collisions, heating/cooling, etc.) ?
It's not that there might not be processes that could create them, but these are objectively observed to have isotope ratios that would require a different elemental soup than found in the bulk molecular cloud. They are older than the Solar System and must have originated in a different environment (in a supernova).

Ah, right - thanks. You did mention the usefulness of isotopes before.

by **Chris Peterson** » Fri Sep 22, 2023 2:17 pm

johnnydeep wrote: ↑Fri Sep 22, 2023 2:09 pm
Chris Peterson wrote: ↑Fri Sep 22, 2023 1:38 pm
johnnydeep wrote: ↑Fri Sep 22, 2023 1:28 pm

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).
Thanks. And just to stick a pin in this point, those particular minerals are such that they couldn't possibly have been formed by any of the known processes going on in the still-forming solar system (high speed collisions, heating/cooling, etc.) ?

It's not that there might not be processes that could create them, but these are objectively observed to have isotope ratios that would require a different elemental soup than found in the bulk molecular cloud. They are older than the Solar System and must have originated in a different environment (in a supernova).

by **johnnydeep** » Fri Sep 22, 2023 2:09 pm

Chris Peterson wrote: ↑Fri Sep 22, 2023 1:38 pm
johnnydeep wrote: ↑Fri Sep 22, 2023 1:28 pm
Chris Peterson wrote: ↑Fri Sep 22, 2023 7:48 am

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).

Thanks. And just to stick a pin in this point, those particular minerals are such that they couldn't possibly have been formed by any of the known processes going on in the still-forming solar system (high speed collisions, heating/cooling, etc.) ?

by **Chris Peterson** » Fri Sep 22, 2023 1:38 pm

johnnydeep wrote: ↑Fri Sep 22, 2023 1:28 pm
Chris Peterson wrote: ↑Fri Sep 22, 2023 7:48 am
RocketRon wrote: ↑Fri Sep 22, 2023 6:18 am 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).

by **johnnydeep** » Fri Sep 22, 2023 1:28 pm

Chris Peterson wrote: ↑Fri Sep 22, 2023 7:48 am
RocketRon wrote: ↑Fri Sep 22, 2023 6:18 am 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?

by **Ann** » Fri Sep 22, 2023 9:29 am

Chris Peterson wrote: ↑Fri Sep 22, 2023 7:48 am
RocketRon wrote: ↑Fri Sep 22, 2023 6:18 am 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

by **Chris Peterson** » Fri Sep 22, 2023 7:48 am

RocketRon wrote: ↑Fri Sep 22, 2023 6:18 am 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.

by **RocketRon** » Fri Sep 22, 2023 6:18 am

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 ...

by **RocketRon** » Fri Sep 22, 2023 5:31 am

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

by **Chris Peterson** » Fri Sep 22, 2023 3:35 am

RocketRon wrote: ↑Fri Sep 22, 2023 3:33 am 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.

by **RocketRon** » Fri Sep 22, 2023 3:33 am

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 ?)

by **Chris Peterson** » Fri Sep 22, 2023 1:01 am

RocketRon wrote: ↑Thu Sep 21, 2023 10:41 pm
wrote: 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.

by **RocketRon** » Thu Sep 21, 2023 10:43 pm

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 ...

by **RocketRon** » Thu Sep 21, 2023 10:41 pm

wrote: 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

by **Chris Peterson** » Thu Sep 21, 2023 9:01 pm

RocketRon wrote: ↑Thu Sep 21, 2023 8:48 pm 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.

Pastorian wrote: ↑Thu Sep 21, 2023 2:56 pm 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.

by **RocketRon** » Thu Sep 21, 2023 8:48 pm

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.

Pastorian wrote: ↑Thu Sep 21, 2023 2:56 pm 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

by **orin stepanek** » Thu Sep 21, 2023 4:53 pm

Amazing what Science can do!

by **johnnydeep** » Thu Sep 21, 2023 3:06 pm

Pastorian wrote: ↑Thu Sep 21, 2023 2:56 pm 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!

by **Pastorian** » Thu Sep 21, 2023 2:56 pm

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.

by **johnnydeep** » Thu Sep 21, 2023 2:05 pm

Chris Peterson wrote: ↑Thu Sep 21, 2023 2:02 pm
johnnydeep wrote: ↑Thu Sep 21, 2023 1:56 pm
Chris Peterson wrote: ↑Thu Sep 21, 2023 1:47 pm

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.

by **Chris Peterson** » Thu Sep 21, 2023 2:02 pm

johnnydeep wrote: ↑Thu Sep 21, 2023 1:56 pm
Chris Peterson wrote: ↑Thu Sep 21, 2023 1:47 pm
Roy wrote: ↑Thu Sep 21, 2023 1:32 pm 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.

Starship Asterisk*

APOD: Tagging Bennu (2023 Sep 21)

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