Re: APOD: Tagging Bennu (2023 Sep 21)
Posted: Fri Sep 22, 2023 2:09 pm
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.) ?Chris Peterson wrote: ↑Fri Sep 22, 2023 1:38 pmQuite 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).johnnydeep wrote: ↑Fri Sep 22, 2023 1:28 pmAre those "unaltered grains" composed of a small number of types of molecules/minerals/etc., or is there wide variation?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.