Terrestrial hot springs are natural laboratories for studying the limits of life and testing strategies for detecting biosignatures on Mars and other planetary bodies. I have conducted research in Yellowstone National Park, the El Tatio geyser field in Chile, in collaboration with colleagues from Dartmouth College, Montana State University, and international partners. My work focuses on archaeal lipid biomarkers and the environmental controls on microbial communities in these extreme settings. These studies provide insight into how microbial signatures are generated, preserved, and recognized across planetary environments.