Almost missed this one… PNAS (Proc. Natl. Acad. Sci.) covers mostly biochem and molecular bio, like many science publications. Those are fields with a lot going on now, so astro is rare. Rare, but not zero- in the Feb. issue (vol. 123 #8):
Baczynski, A. A. Mcintosh, O. M. Simkus, D. N. et al. Multiple formation pathways for amino acids in the early Solar System based on carbon and nitrogen isotopes in asteroid Be… e2517723123 .2517723123
Yes, organic chemicals. We had previously found organic chemicals in meteorites- the carbonaceous chondrite ones, and even some in other types. But the question remained: are these really extraterrestrial molecules, or were the meteorites contaminated once the arrived on our (living) planet? That was part of the point of OSIRIS-REx (plus Hayabusa2). They did not merely recover samples of carbonaceous chondrite asteroids, but did so using known, sealed, sterile handling equipment.
Now comes the payoff: comparing the extraterrestrial(?) organics already seen in meteorites with the known asteroidal samples recovered by the spacecraft. As our meteoritic “control” specimen, the Murchison meteorite is a stand-in for other carbonaceous chondrites. “Murchison, like Bennu, is hydrated and organic-rich and used as the comparative baseline”. With a large sample, recovered from the Australian desert, the Murchison data is as reasonably statistically significant and less-contaminated as one could hope to expect from a meteorite. (Basically, we would have to catch a meteorite, of this type, in mid-air to get lower contamination levels.) And what do we see?
The Murchison data on organics, vs. Bennu, is similar, yet not a match. Using isotopes (13C and 15N) as chemical tracers, it appears that not only can organic molecules form in space, but they can form readily, using multiple sources and pathways. These samples- originally from the outer Solar System, by roundabout routes- are just lousy with the ingredients of life.
Carbonaceous-chondrite meteorites and now, carbonaceous-chondrite asteroids; is there any reason NOT to study them?