August 29, 2025

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Speaker: Ralph Milliken, Professor, Brown University

Host: Sean Gulick

Title: Red Light, Blue Light: Returned Samples from Near-Earth Asteroids and Implications in the Search for Key Ingredients for Life

Abstract:

Water and organic-bearing asteroids have played a fundamental role in the delivery of these materials to Earth throughout its history, yet many questions remain about the inventory of these objects and their geologic histories.

Recent missions such as Japan’s Hayabusa2 and NASA’s OSIRIS-REx spacecraft have observed and sampled two of these objects in near-Earth space, allowing for detailed understanding of the origin, evolution, and composition of primitive, carbon-bearing asteroids. Laboratory analyses of the returned samples reveal a diverse array of hydrated minerals and organic compounds, and spectral reflectance measurements of these materials provide a means to better understand how to identify similar objects throughout the Solar System. Ground- and space-based reflectance measurements remain the primary means for identifying and classifying asteroids, and the returned samples have provided unprecedented insight into how these data may be better interpreted and an opportunity to reevaluate long-held assumptions.

Biography: Dr. Ralph Milliken, Professor in the Department of Earth, Environmental, and Planetary Sciences at Brown University, received his B.S. in Geology from Indiana University (2001) and M.S. and Ph.D. in Geology from Brown University (2006). After receiving his doctorate he spent four years at NASA’s Jet Propulsion Lab/California Institute of Technology. Prof. Milliken joined the faculty at Brown in 2012 after two years on the faculty at the University of Notre Dame. His research interests include understanding the origin and role of water in the formation and evolution of the Solar System, the use of remote sensing techniques to determine the composition and geologic history of planetary bodies, and unraveling the sedimentary rock record of Mars. He is the science manager of the NASA-funded Reflectance Experiment Laboratory (RELAB) at Brown University and has participated on a number of U.S. and international planetary missions, including ESA’s Mars Express, JAXA’s Hayabusa2, and NASA’s Mars Reconnaissance Orbiter, Curiosity rover, and OSIRIS-REx missions. Prof. Milliken is also deeply interested in increasing access to high quality STEM education in underserved communities, engaging the public about what we are learning from NASA missions, and promoting the benefits of space exploration, activities that he promotes through his role as Director of the NASA Rhode Island Space Grant Consortium and Director of the NASA Rhode Island Established Program to Stimulate Competitive Research (EPSCoR).