On December 5, 2023, I went to an in-person lecture experience titled "Small bodies: primitive witnesses to the birth of a habitable solar system" by Karen Meech, from the institute for Astronomy, University of Hawai 'i, who is an award winning scientist who worked on the deep impact comet probe mission. This speech was part of the Small bodies series of lectures she has been giving. The Lecture was 12/8/2023 in room 2400 of the Atlantic building at 4:00 PM.
The lecture was about astronomy, astrobiology, geology, astrophysics, and chemistry. Karen Meech has been studying small bodies in the solar system (comets, asteroids, etc.) and was using the data to help infer about the formation of the earth and the rise of life. First, she went over the basics of habitability. I learned that habitability is water + organic molecules + a rocky planet + the right temperature. Curiously, our solar system has less water when compared to other systems we have studied.
One of the main questions was is the solar system an unusual solar system compared to others. In order to study this, we need to turn to the remnants of planet formation that have remained almost unaltered for 4.5 billion years, in the form of comets. Firstly - How did the earth get its water? Multiple explanations have been proposed. One is that earth formed its own water from iron oxide in lava reacting with H2 gas in the atmosphere. Another is that asteroids and comets brought it to earth in impacts. A third is that Earth collected water gas from the space around the protoplanet. In fact, theories for the total amount of water on earth, included in the crust, mantle, and core, range from 1.5 oceans to 70 oceans.
To try and solve these questions, Karen turned to studying Comets. Different comets and asteroids, depending on their type, area of formation in the solar system, and orbit, contain different chemical markers. The main one discussed was the Deuterium to Hydrogen ratio. She found that many comets and asteroids have D/H ratios similar to or higher than Earth's D/H ratio. This lends credence to the water by impact theory.
The conclusion of the lecture was that the study of Earth's origins is interdisciplinary, and that much of the chemical story of Earth's origin will require in-situ exploration ie. a space mission.