The Earth and Planetary Science Letters issue for September, vol. 641, links both Earth and P.S.:
Zhang, Y. Qin, L. Mo isotope evidence for evaporation loss of volatiles in CKs, and implications fo…
Art 118807
Van Meldeghem, F. Maeda, R. Soens, B. et al. Chrome-rich spinels in micrometeorites from mod… Art 118837
We know the Earth accreted from smaller pieces coming together; it’s a question of which pieces, and possibly some dependence on the order (the “late veneer”). Some of the pieces (basically, meteors) came from primordial, preserved asteroids, and some didn’t. The CK meteorites are samples we have of asteroids that didn’t- didn’t stay primordial, and didn’t preserve their initial composition since they formed, along with the rest of the Solar System. So, what happened? If we can deduce the geologic history of some of these processed meteorites (though clearly, less-processed and more-primitive than Earth, or even Earth’s satellite), then we’re one step closer. And regardless of the implications for Earth, knowing the history of the early, new-formed Solar System is knowledge we’d like to have.
As I mentioned last week, don’t just brush off dust. Dust is the alpha anapd omega, the progenitor and progeny of asteroids. Asteroids (thus, everything eventually) form from firsthand- or secondhand-products of dust accretion. On the flipside, the eventual fate of an asteroid is dust. Either they grind each other to bits, they crash into a planet (and turn to bits that way), or they are flung into the Sun, breaking up before literal contact and turning into a dust wisp. Antarctica, as a white, clean, featureless expanse, is arguably our best place for dust studies. Here, Van Meldeghem et al. note Cr-rich spinels in dust collected in Antarctica. Spinels in general, and chromium isotopes, both act as tracers. What do two(ish) tracers tell us regarding this cosmic trail, and its history?