As the lunar module pilot for Apollo 11, Buzz Aldrin remains the most well-known figure in the aerospace industry today and a consistent advocate for human exploration of Mars. He has long pushed for the concept of a “cycler,” a semi-permanent spacecraft in orbit around the Sun that would carry cargo and crew between Earth and Mars periodically.

But in recent years Aldrin has begun to embrace the world that made him famous—the Moon—as a critical waypoint on the road to Mars. This involves the collection of lunar ice, believed to be accessible at the poles, for use as propellant to send astronauts deeper into space.