space. Young thereafter commanded Gemini 10 (1966), flying with Michael Collins. Eugene Cernan, the lunar module pilot, was a 35-year-old commander in the Navy at the time of Apollo 10. A 1952 graduate of Purdue University, he entered the Navy after graduation. Selected as one of the third group of astronauts in 1963, Cernan flew with Stafford on Gemini 9A before his assignment to Apollo 10. With five prior flights among them, Apollo 10 had the most experienced American crew to reach space prior to the Space Shuttle era, and the first American space mission to have a crew consisting entirely of spaceflight veterans. As Apollo flights were planned in 1966, Stafford was announced as backup CMP for the second crewed Apollo flight, planned as an extended test of the command module, and dubbed Apollo 2, with Frank Borman as backup commander and Collins as backup LMP. After the prime crew of Apollo 2, led by Wally Schirra, went to NASA management with a list of demands concerning their mission, Apollo 2 was cancelled in November 1966, and Stafford was assigned as backup commander for the second Apollo mission under a new schedule, planned to involve the first crewed flight of the lunar module, to be commanded by James McDivitt, with Young as backup CMP and Cernan as backup LMP. The Apollo 1 fire in January 1967 led to a rescheduling of Apollo flights, and Stafford's crew was assigned as backups for the first crewed fight. which became Apollo 7, flown by Schirra's crew. The backup crew for Apollo 10 was L. Gordon Cooper Jr as commander, Donn F. Eisele as command module pilot and Edgar D. Mitchell as lunar module pilot. By the normal crew rotation in place during Apollo, Cooper, Eisele and Mitchell would have flown on Apollo 13, but Cooper and Eisele never flew again: Deke Slayton, Director of Flight Crew Operations, felt that Cooper did not train as hard as he could have, while taking risks such as auto racing. Eisele was blackballed because of incidents during Apollo 7, which he had flown as CMP and which had seen conflict between the crew and ground controllers; he had also been involved in a messy divorce. Slayton only assigned the two as backups because he had few veteran astronauts available. Cooper and Eisele were replaced by Alan Shepard and Stuart Roosa respectively. George Mueller rejected the Apollo