Apollo 11 the CMP on the Apollo 8 crew, began experiencing trouble with his legs. Doctors diagnosed the problem as a bony growth between his fifth and sixth vertebrae, requiring surgery. Lovell took his place on the Apollo 8 crew, and, when Collins recovered, he joined Armstrong's crew as CMP. In the meantime, Fred Haise filled in as backup LMP, and Aldrin as backup CMP for Apollo 8. Apollo 11 was the second all-veteran crew on an American mission, the first being that of Apollo 10. The next was STS-26 in 1988. The backup crew consisted of Lovell as Commander, William Anders
NASA space-flown Gemini and Apollo medallions also struck, in very small numbers, in 14k gold. These medallions were generally ordered by the mission crew as a personal memento of their flight and were often taken to the lunar surface in the Landing Module. For the duration of the Apollo program, Robbins medallions (3–7 gold and 80–450 silver per mission) were flown into space. Despite the NASA prohibition on commercializing the medallions, since 1995 there have been over 500 internet or live auction appearances of Apollo mission Robbins medallions. Two auction companies account for a majority of the sales: Heritage Auctions (over 200 since 2007) and RR