Let’s take a little trip, a trip back to the young Solar System. In the 15 Nov Icarus (vol. 423):
Serra, C. Vinogradoff, V. Danger, G. et al. Unexpected mineral impact on organic evolution durin…
Art 116273 .2024.116273
Jenniskens, P. Estrada, P. R. Pilorz, S. et al. Properties of outer solar system pebbles during plane… Art 116229 .2024.116229
Asteroids contain organic chemicals. We know this, because the interstellar medium contains organic chemicals, and many meteorites contain organic chemicals. A reasonable person would assume- even before we had Ryugu/Bennu samples- that interstellar organics landed on, and condensed into, new-formed small bodies (as did ice crystals, also drifting through space). And yes, our samples of Ryugu (from Hayabusa2) and Bennu (from OSIRIS-REx) confirm that assumption. But then what? Various small bodies experienced various heating levels, from accretion (impacts, and the general condensation/compaction process- the “Kelvin-Helmholtz mechanism”.) Some organics will be heat-tolerant, some will not… and the presence of water (from melting, fluidized ices) doesn’t help things. Then, to water, we can add the mineral background. Some minerals will participate in a reaction, or simply act as a bed for reactions. Serra et al. ran tests on such rock-water-organic mixtures. A reasonable person would not expect their results.
Stellar systems contain pebbles. We know this, because the interstellar medium contains dust particles, we can see the signatures of dust and pebbles in the light from the debris disks around new-formed stars, and we can see pebbly textures (sometimes, intact pebbles themselves) in certain types of meteorites. When a meteor phenomenon happens (the entry of particles into our atmosphere), we are seeing the pebbles firsthand (a space pebble) or secondhand (a piece shed from a comet or active asteroid). Certain types of pebbles- size, density, etc.- will have certain properties in the meteor phenomena. Denser, stronger meteorites produce longer, brighter meteors, etc. We can even use spectrographs to say something about the composition of the pebble, from its light signature. Jenniskens et al. studied numerous meteor records (and Jenniskens would know- his career would make him ‘Dr. Meteor’) to see what we might deduce of the initial pebbles. One of those records is the prior orbit of the pebble before it stopped. Imaging the meteor streak, from a known observation site, gives a vector; two observing sites let us triangulate the 3-D path. Extending that path well ahead of its Earth intercept gives the orbit of the free pebble, or pebble parent. What does a meteor trail tell us of the composition and (prior) orbit of these space bodies? The two questions are related: bodies from the outer Solar System should be different in density and strength than ones that formed in the inner Solar System… and what of the middle Solar System?
There’s some stuff we don’t know about the early Solar System… and there’s a lot we’ve figured out. Here are two groups, at minimum, on the trail.