backup crew of Apollo 14 would be Gene Cernan, Ronald Evans, and former X-15 pilot Joe Engle. This put them in line to be the prime crew of Apollo 17, because the Apollo program's crew rotation generally meant that a backup crew would fly as prime crew three missions later. Harrison Schmitt, who was a professional geologist as well as an astronaut, had served on the backup crew of Apollo 15, and thus, because of the rotation, would have been due to fly as lunar module pilot on Apollo 18. In September 1970, the plan to launch Apollo 18 was cancelled. The scientific community pressed NASA to assign a geologist, rather than a pilot with non-professional geological training, to an Apollo landing. NASA subsequently assigned Schmitt to Apollo 17 as the lunar module pilot. After that, NASA’s director of flight crew operations, Deke Slayton, was left with the question of who would fill the two other Apollo 17 slots: the rest of the Apollo 15 backup crew (Dick Gordon and Vance Brand), or Cernan and Evans from the Apollo 14 backup crew. Slayton ultimately chose Cernan and Evans. Support at NASA for assigning Cernan was not unanimous. Cernan had crashed a Bell 47G helicopter into the Indian River near Cape Kennedy during a training exercise in January 1971; the accident was later attributed to pilot error, as Cernan had misjudged his altitude before crashing into the water. Jim McDivitt, who was manager of the Apollo Spacecraft Program Office at the time, objected to Cernan's selection because of this accident, but Slayton dismissed the concern. After Cernan was offered command of the mission, he advocated for Engle to fly with him on the mission, but it was made clear to him that Schmitt would be assigned instead, with or without Cernan, so he acquiesced. The prime crew of Apollo 17 was publicly announced on August 13, 1971. When assigned to Apollo 17, Cernan was a 38-year-old captain in the United States Navy; he had been selected in the third group of astronauts in 1963, and flown as pilot of Gemini 9A in 1966 and as lunar module pilot of Apollo 10 in 1969 before he served on Apollo 14's backup crew. Evans, 39 years old when assigned to Apollo 17, had been selected as part of the fifth group of astronauts in 1966, and had been a lieutenant commander in the