Renyu Hu

Renyu Hu is a Research Scientist at the Jet Propulsion Laboratory and a Visiting Associate in Planetary Science at the California Institute of Technology. He received his B.S. from Tsinghua University in 2007, a Diplome d'Ingenieur from Ecole Centrale Paris in 2009, an M.Sc. from Tsinghua University in 2009, and a Ph.D. from MIT in 2013. Dr. Hu was a Hubble Fellow at JPL from 2013-2015 and has been affiliated with Caltech since 2015.

Dr. Hu's research focuses on the chemical and physical processes of exoplanet atmospheres and their evolution, methods to detect rocky exoplanet surfaces, and Mars atmospheric evolution. His work aims to identify and characterize habitable environments in the solar system and beyond through advanced numerical models and various observational techniques. He has developed frameworks for characterizing surfaces of rocky exoplanets that have motivated over 15 ongoing JWST observation programs, and demonstrated rich chemistry in temperate sub-Neptune atmospheres that informs how to distinguish potentially habitable worlds.

His most notable recent work includes the discovery of a secondary atmosphere on the rocky exoplanet 55 Cancri e using JWST, which is sustained by a magma ocean and likely rich in CO and CO₂. This work, published in Nature in 2024, represents a critical breakthrough in identifying habitable environments beyond our solar system. His research group has also characterized LHS 1140 b as a potentially habitable water world and explained JWST spectra of K2-18 b and TOI-270 d through chemical signatures of temperate sub-Neptunes.

• Hubble Fellow, JPL, 2013-2015
• Best poster award at JPL Research Day (awarded to postdoc Armen Tokadjian, May 2024)

Dr. Hu leads significant research initiatives including NASA's Study Analysis Group on exoplanet reflectance spectroscopy for the Habitable Worlds Observatory and chairs the 'Characterizing Exoplanets' working group for this flagship mission. His group has secured over 100 hours of JWST observation time for programs characterizing TOI-4336 b (a temperate water world candidate) and TOI-199 b (an exo-Saturn). He has developed multiple software tools including EPACRIS (ExoPlanet Atmospheric Chemistry & Radiative Interaction Simulator), ExoREL (Exoplanet REflected Light), ExoTR (Exoplanetary Transmission Retrieval), and CANARY for modeling planetary atmospheres.