I'm interested in planetary materials, including their early evolution in the solar system, re-creating their exotic properties in the lab, and extracting them sustainably as space resources.
Dec 11, 2:28pm: Ancient Hydrated Silicates in the Martian Deep: Crustal Density, Water Budget, and Astrobiology. 2018 AGU Fall Meeting, Walter E. Washington Convention Center 206.
1. Carbonaceous muds (Recent abstract).
2. Martian clay formation and noble gas sequestration in the pre-Noachian (Recent publication).
3. High fidelity regolith simulants (Recent publication).
The planets and moons of our solar system formed and evolved according to two sets of principles: basic physical and chemical ground rules, and chance events. For example, giant impacts are a natural consequence of the leftover crud from star formation careening around in orbital dynamics space. However, the specific collision between Earth and a Mars-sized body to form the Moon was a random even that, given slightly perturbed initial conditions, may not have happened. But does this matter? If you shuffle a deck of 52 playing cards, there was a 1 in 8x1067 chance that you ended up with the specific order of cards that you did. On the other hand, that’s the order the cards are in, so does it make sense to dwell on the probability of arriving at that point in hindsight? Or to think about the other paths not taken? (The anthropic principle comes to mind here).
Perhaps though, this way of thinking provides a means to understand the variety and evolution of exoplanets and exomoons. Because the number of extrasolar systems is so large (1024 from one estimate by David Kornreich, assuming every star has planets), the universe is essentially a massive Monte Carlo experiment in how to make a solar system. Every possible system that obeys the laws of physics and chemistry should exist. What this allows us to do then, is to think about chance events that played out in our own planetary neighborhood and ask: what if X never happened? Or if Y happened…a little to the left? The answers may not shed light on our own planets, but these potentialities almost certainly played out on exoplanets light years away. Here’s a couple examples:
(1) It’s fairly well established that a nearby supernova spewed enhanced amounts of the short-lived heat source 26Al into our solar nebula early in its history, which had profound effects on the evolution of planesimals and eventually the planets themselves. But what if that never happened? Very few bodies would have heated up and melted early on, prohibiting differentiation…and on, and on. Perhaps many (most?) exoplanetary systems did not receive a similar injection of 26Al, and evolved quite differently than our own.
(2) It’s even more well established that a gigantic impact occurred on Mars sometime around 4.5 billion years ago, scouring out an elliptical basin to form the northern lowlands and covering the rest of the planet with kilometers of impact melt and ejecta. This event shaped the entire geologic history of Mars: its unique early climate system that resulted from the North-South topographic dichotomy, the pathways of outflow channels into a possible (frozen?) northern ocean, and the burial of Mars’ primitive crust, which may have been deeply altered by an early outgassed atmosphere to form a thick clay-rich layer. What if the impact missed? Out there in the universe are likely trillions of Mars-sized planets in roughly the same orbit where that scenario played out: how did they evolve?
We may be a ways away from Star Trek-like exoplanet designations, but I think it’s worthwhile to consider what “types” of planets (ocean planets, clay planets, desert planets, etc.) are likely to be most common in extrasolar systems, and just how unique (or rare) our own planets are in comparison.