DLS - Karen Meech (University of HI)
Department Lecture Wed October 28 at 4pm:
Zoom link: https://mit.zoom.us/j/94718264224
email firstname.lastname@example.org for the password if you are not on the department mailing list
Using Small Bodies to Understand the Formation of Habitable Worlds
No one knows if our solar system, with a planet possessing the necessary ingredients for life within the habitable zone, is a cosmic rarity. We also don’t understand the contribution that the gas giants played in delivering essential materials necessary for life to the habitable zone. The answers to these questions are contained in volatiles that have been least unaltered since the formation of the giant planets. To access this record, we need: (1) a population of icy bodies that faithfully records the history of volatile migration in the early solar system; (2) a source of volatiles that we can access affordably; (3) knowledge that the volatiles were not altered by aqueous interaction with their parent body; and (4) measurements from multiple chemical markers with sufficient precision to distinguish between original volatile reservoirs. Comets were long thought to be the most likely “delivery service” of Earth’s water. But new models and new data, including Rosetta’s survey of comet 67P, have cast doubt on this. The only way to learn where Earth’s water came from is to match the chemical fingerprints of inner solar system volatiles to a location in the protoplanetary disk. Such data can distinguish between competing models of solar system formation to specify where the water came from and how it was delivered. Main belt comets (MBCs) are the perfect targets for this investigation because they satisfy the criteria outlined above. MBCs are part of a large population of icy asteroids residing in the outer asteroid belt that have emerged as significant reservoirs of primordial water and potentially other volatiles. These icy asteroids may have formed in-situ or been dynamically implanted as the giant planets grew. Unlike true comets, they have remained on stable orbits since the era of planet formation or migration and preserve a record of their accretional environment, frozen in time. Occasionally an MBC gets hit by a meter-scale impactor that strips away part of its insulating dust. The newly exposed volatiles escape into space over an extended period. Detailed isotopic and chemical measurements can distinguish between solar system formation models and thus address the question of forming habitable worlds. Modern all-sky surveys are now discovering new types of small bodies that can help provide additional clues that will allow us to distinguish between dynamical models. In this talk I will talk about what small bodies are telling us about the early solar system along with ideas of missions that can contribute to this understanding.