Shortly after beginning his training Komarov was hospitalised for a minor operation in May 1960, which left him medically unfit for physical training for approximately six months. At the time, the selection criteria placed a heavy emphasis on the physical condition of cosmonauts and any imperfection led to instant disqualification. Since Komarov already held engineering qualifications, he was allowed to remain in the program after assuring the administration he would be able to catch up. He continued with the required academic studies while recovering. He returned to training in October, because his recovery was more rapid than medical staff had expected. During that time he assisted his younger peers with their academic studies; earning him the casual nickname of "The Professor," which he shared with Belyayev, who was two years his senior. In 1961 the first space flights began. By 1962, Komarov was the third-highest-paid cosmonaut, due to his qualifications, rank and experience. He earned 528 rubles a month, with only cosmonauts 1 and 2, Yuri Gagarin and Gherman Titov, being more highly paid.