In the next decade, NASA intends to send astronauts to Mars for the first time. To succeed, crew members will have to overcome unprecedented life-threatening challenges. And while many of these hazards are physical, the most elusive are psychological. Throughout their three-year absence, crew members won’t be able to communicate with Earth in real time due to the immense distance. The psychological impact of this level of disconnectedness and isolation—both from mission control and loved ones—is impossible to predict and endangers the mission itself. Directed to mitigate this threat is Dr. Al Holland, a NASA psychologist whose job is to keep astronauts mentally stable in space. The Longest Goodbye follows Holland, rookie astronauts Kayla Barron and Matthias Maurer, and former astronaut Cady Coleman, among others, as they grapple with the tension between their dream of reaching new frontiers and their basic human need to stay connected to home. This conflict transcends space travel: how do we balance our quest for progress with the deep connection to our history and each other?