NASA’s Astrobiology Institute (NAI) was a cross-divisional research institute established in 1998 as a research institute without walls. Managed by NASA Ames, it brought together geographically distributed interdisciplinary teams in astronomy, biology, geology, and planetary science, funded astrobiology research through five-year Cooperative Agreement Notices, and was sunset at the end of 2019 as NASA shifted community coordination to Research Coordination Networks.