Irwin was one of three astronauts who participated in Apollo 15—the all-UM mission in 1971. Along with David Scott, 1949-50, HDAS’71, he logged more than 18 hours of excursions on the moon’s surface and collected about 175 pounds of lunar materials. They also left behind a certificate establishing the U-M Club of the Moon, which the Alumni Association recognizes to this day. Alfred Worden, MSE’63, HDAS’71—the third alumnus on the mission—piloted the command module, spending three days alone.