The Effects of Early Collisional Evolution on Amorphous Water Ice Bodies

Abstract Conditions in the outer protoplanetary disk during solar system formation were thought to be favorable for of amorphous water ice (AWI), a glassy phase ice. However, subsequent collisional processing could have shock-crystallized any AWI present. Here we use iSALE shock physics hydrocode simulate impacts between large icy bodies at impact velocities relevant these environments, and then feed results into custom-built crystallization script, compute how much crystallizes/survives events. We find that speeds after planet migration (i.e., trans-Neptunian objects) are too slow crystallize meaningful fraction AWI. During migration, however, amount crystallizes is highly stochastic: relatively little lower (less than ∼2 km s −1 ), yet most present (if equally sized) or impactor site different sizes) higher (greater ∼4 ). Given suspected ∼2–4 , this suggests primordial AWI’s ability survive stochastic. if proto-Edgeworth–Kuiper Belt (proto-EKB) objects their fragments experienced multiple events, nearly all crystallized; such proto-EKB consistent with lack unambiguous direct detection on body. Ultimately, survival day depends sensitively proto-EKB’s size–frequency distribution, which currently poorly understood.