Renyu Hu’s Homepage

Renyu Hu, PhD

Research Scientist, Jet Propulsion Laboratory

Starshade Scientist, NASA Exoplanet Exploration Program

B.S., Tsinghua University, 2007; M.S., Tsinghua Univerisity, 2009; Diplome d’Ingenieur, Ecole Centrale Paris, 2009; Ph.D., Massachusetts Institute of Technology, 2013.

I am a planetary scientist with expertise in modeling the physical and chemical processes that shape the atmospheres on planets and exoplanets. My research strives to identify and characterize habitable environments in the Solar System and beyond, using telescopic, satellite, and in-situ measurements.                                                                                                                                                                                                                                                                                                 

Astronomers are on the cusp of observing the atmospheres of the first groups of Earth-temperature exoplanets and finding out whether they could host habitable environments. My recent research demonstrated that these temperate worlds will have rich chemistry in the atmosphere, and I have developed a novel method to use JWST to tell whether temperate sub-Neptune planets have massive atmospheres (i.e., uninhabitable) or thin atmospheres (i.e., potentially habitable). Moreover, we have obtained >100 hours in Cycle 1 of JWST to carry out the first such observations!

Other significant findings on exoplanets:

• The “O₂-CO Runaway” state as the most likely habitable state on rocky exoplanets of late M dwarf stars, such as TRAPPIST-1
• Evidence for an atmosphere on a super-Earth exoplanet (55 Cnc e)
  
• Helium atmospheres on some exoplanets as the outcome of extensive atmospheric evolution

Recent significant findings on Solar System planets:

• A nitrogen-rich early atmosphere on Mars consistent with isotopic evolution models
• Long-term drying of Mars by sequestration of ocean-scale volumes of water in the crust
• Strong diurnal variation in D/H of surface water on Mars

I also provide science cases, analyses, and leadership to enable future space missions to better observe and characterize potentially habitable exoplanets. I am Starshade Scientist of the NASA Exoplanet Exploration Program. In this role, I provide science leadership to the Starshade Technology Development to TRL-5 (S5) activity and manage NASA’s Starshade Science and Industry Partnership program, including the Starshade Exoplanet Data Challenge. My atmosphere models are used to determine what we can learn about exoplanets from direct-imaging observations:

• ExoREL-R (Exoplanet REflected Light - Retrieval): a novel, fully Bayesian atmospheric retrieval tool for exoplanet reflected light spectra
• The near-infrared band is essential to characterize terrestrial exoplanets beyond modern Earth analogs in the reflected light

I have created several model tools to simulate important atmospheric processes and to analyze observations:

• A general atmosphere chemistry and radiation transfer model for atmospheres of any oxidation states
  • Compositional diversity of thick atmospheres on warm and hot super-Earths and sub-Neptunes
• The first model for simulating spectral features of surface minerals on bare-rock exoplanets
  • The first bare-rock exoplanet (LHS 3844b) detected!
• A general retrieval method to extract cloud information from visible-wavelength phase curves of exoplanet
  • Inhomogeneous clouds are common in hot Jupiters!

My curriculum vitae can be found here.