One of NASA’s astronaut candidates is stepping down “for personal reasons,” a NASA spokeswoman said Monday. Robb Kulin was one of 12 people selected last year for training, with the possibility of eventually going to outer space. Before joining NASA, Kulin was a senior manager for flight reliability at SpaceX. “Hopefully, I will one day fly on a vehicle that has components that I got to design,” Kulin said at a June 2017 press conference announcing the new class of potential astronauts. It is very rare for candidates to leave NASA. “The last time that a NASA astronaut candidate resigned before being qualified for a potential spaceflight assignment was 50 years ago, in 1968,” space historian Robert Pearlman told Ars Technica, referring to astronaut John Llewellyn.