Topical (or would that be subdural?) work in the May (v. 372) Geochimica et Cosmochimica Acta:
Fowler, S. J. Sherman, D. M. Brodholt, J. P. et al. Mineral-water reactions in Earth’s mantle: Predictions from Born theory and … p. 111 .03.012
Where’s the ‘cosmo’ in this cosmochimica, you ask? Here’s the cosmo-, the astero-:
Bland, P. A. Travis, B. J. Giant convecting mud balls of the early solar system , Science Advances v. 3 #7 e1602514 .160251
The old assumption was that “comet == watery, asteroid == dry”. Then people had to backpedal to “comet == watery now, asteroid == dry now” or “comet == watery and leaky now”. Then people had to keep backpedaling to “comet == solid water” (no aqueous alterations from unbound, pooling water). At this point, we might as well have backpedaled to “comet* (but note discovery circumstances… subject to revision)”.
The authors follow up with “More mudballs: simulating primordial planetesimals as unconsolidated mixtures of mud and chondrules” (Bland, P. Travis, B. 2014 77th MetSoc p. A44).
Asteroids, if large enough, had geologic processes like- and unlike- here on Earth. Bland and Travis found that ‘large enough’ could be as low as tens of kilometers, which would be… thousands and thousands of asteroids in the early Solar System. These bodies displayed processes resembling plate tectonics as on Earth (except aqueous and thinner, not magmatic). Such bodies left traces, now called CM (and likely CI) chondrite meteorites.
The old assumptions were old assumptions, and we’re well past them. Too bad too many people aren’t past them, and imply revision.