LExEN is an acronym for Life in Extreme Environments. It was originally developed by G. Michael Purdy in 1997 as an area of research in which scientists could seek funding for activities in the polar regions, and overseen by the National Science Foundation as a highly interdisciplinary, integrated research program. Participating were the Directorates for Biological Sciences, Mathematical and Physical Sciences, Engineering, Geosciences, and the Office of Polar Programs of the National Science Foundation. The program sought to place a strong emphasis upon those life-supporting environments that exist near the extremes of planetary conditions. The study of extreme habitats, both planetary and extra-planetary, was underpinned by the idea that "deep understanding of certain earth-bound microbial systems would provide important insights into life-sustaining processes and the origin of life on our own planet, while illuminating the search for life in other planetary environments."
In 1999 it was announced that the future of LExEN was still under consideration but despite the lack of research in the topic, the program no longer appears on the NSF A-Z Index of Funding Opportunities.