Born and raised in the state of Kentucky, Sarah Stewart Johnson is now a PhD student at the Massachusetts Institute of Technology. During her time at Washington University in St. Louis, Sarah studied mathematics, environmental studies and planetary science. She lived for six months in the rainforests of Costa Rica and spent two years at Magdalen College, Oxford as a Rhodes Scholar. During 2002, Sarah joined a five week British expedition to complete biodiversity surveys in remote gallery forests along the banks of the Fiherenana River in Madagascar. She was a student delegate to the United Nations Climate Summit at The Hague in 2000 and currently serves on the Editorial Board for the Journal of Astrobiology. Sarah's planetary science research revolves around modeling the history of water on Mars and exploring the prospects for subsurface life.