GLOW: Exploring effects of rocky exoplanet composition on habitability and target selection

The composition of rocky planets orbiting other stars (exoplanets) can differ according to silicon, magnesium, calcium, and aluminum content. These differences relative to Earth may impact their planetary evolution and habitability. In previous lab experiments on materials like those expected for rocky exoplanets, the project team found small changes in composition could suppress the cycling of elements necessary for life and cause a long-lived lava ocean. In this project, high pressure and temperature experiments are carried out on materials with a wider variety of element ratios to cover the potential spread of exoplanet properties. As a result, astronomers will be able to target stars whose planets are most likely to have Earth-like geochemical conditions. A graduate student and several undergraduate students will be trained in laboratory methods. Training in science communication for the project’s students will culminate in disseminating the project via public outreach events and an episode of “Strange New Worlds: A Science and Star Trek Podcast.” Petrologic experiments on hypothetical bulk silicate exoplanet compositions different from Earth or other solar system bodies will be performed to acquire fundamental data about how planet compositions influence long-term habitability, as well as planetary cooling and structure. This project consists of five tasks: (1) conduct initial set of experiments on four hypothetical exoplanet compositions to determine shallow mantle melting curves, melt compositions, and melting reactions; (2) use results from Task 1 to guide selection of compositions for a second set of experiments; (3) conduct a second set of experiments on four hypothetical exoplanet compositions selected in Task 2; (4) package data for incorporation into the geochemical modeling code exoMELTS; and (5) prepare a prescriptive filter of FGK-type stars that are likely to host geochemically habitable exoplanets on the Hypatia Catalog website. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.