Geronimo L. Villanueva (born April 9, 1978) is a planetary astronomer at NASA Goddard Space Flight Center. Some of his contributions include the identification of an ancient ocean on Mars, sensitive searches of primordial water in comets, and the search and possible discovery of organics on Mars.His work on high-resolution molecular spectroscopy of planetary and cometary atmospheres led the International Astronomical Union to name minor planet 9724 after Villanueva, while the American Astronomical Society awarded him the Urey Prize (young planetary scientist of the year) in 2015.