The latest issue of Science Advances (1 Aug, vol. 11 #31) has something other than microbio, chem, or field bio… yes, an actual astronomy paper:
Kruttasch, P. M. Mezger, K. Time of proto-Earth reservoir formation and volatile element depletion from 53Mn-53Cr chronometry eadw1280
There’s one thing we’re sure of: Earth (and the other planets) formed by swallowing meteors. The planets grew til the early Solar System was largely cleared, and no material was drifting around to swallow up. But the farther and farther we get from this concept, the fuzzier and fuzzier things look.
Where did those meteors come from- the early Solar System was not one continuous, well-mixed reservoir. Different meteors have different element and isotope budgets, and would leave signs of themselves in the resulting planets they formed. To an extent, we see the signatures of enstatite chondrite meteorites in the bulk Earth: our isotope budget looks, mostly, like the enstatite chondrite isotopes. But not exactly: other meteorite groups had mixed to produce the final Earth.
Kruttasch Mezger 2025 are on the trail: they use the tracer isotopes of Manganese and Chromium to gauge meteorites as potential building blocks of planet Earth. These elements form oxides under earthlike conditions, and the two oxides are then pretty stable- hence, their use as tracers.
The result is, broadly, in line with other results. Earth formed from a lot of enstatite chondrites, got hit by a giant impact, and kept swallowing a few more meteorites- the “late veneer”. Some of the stragglers were carbonaceous chondrites, from the outer Solar System. But which carbonaceous chondrite groups? When?