Sarah Joiret is a NOMIS–ETH Fellow at the Centre for Origin and Prevalence of Life at ETH Zurich (Switzerland). She will conduct her research under the mentorship of Caroline Dorn beginning in September 2026.
Joiret is a planetary scientist from Liège, Belgium. She is particularly interested in the dynamical evolution of planetary systems and its role in the transport and delivery of volatiles. Prior to her PhD, she spent a year at the European Space Agency, where she developed her interest in solar system dynamics. She then completed her PhD at the University of Bordeaux, France, in collaboration with the Institut de Physique du Globe de Paris and the University of Bristol, UK. Her project was highly interdisciplinary, combining dynamical modeling and experimental geochemistry to constrain the role of comets in delivering volatiles to the early Earth. Joiret’s current postdoctoral research at the Collège de France extends this approach to Mars, providing new constraints on its early evolution.
Research Focus
A central question in understanding planetary habitability is whether the volatile inventory that sustains life, and particularly water, originates primarily from accretion during planetary formation or from later delivery by small volatile-rich bodies. As a NOMIS–ETH Fellow, Joiret will investigate the latter hypothesis. In particular, she will explore how the architecture and dynamical evolution of planetary systems influence the probability of cometary impacts, and how these processes may affect the C/O ratio and volatile content of planetary atmospheres under different end-member scenarios. On Earth, comets likely contributed only minor amounts of water, carbon and nitrogen-bearing species. However, different planetary system architectures may lead to significantly different cometary contributions. The ultimate goal of Joiret’s project is to quantify the role of cometary delivery in shaping atmospheric composition across planetary systems.
Feature image: Sarah Joiret portrait by Patrick Imbert. Right: What is the role of cometary delivery in shaping atmospheric composition across planetary systems? (Image: Pixabay and Pexels, via Canva)