After visiting his father and stepmother in New York, Carpenter returned to Boulder in November 1945 to study aeronautical engineering at the University of Colorado at Boulder. He was given credit for his previous study, and entered as a junior. While there he joined Delta Tau Delta International Fraternity. He was severely injured in a car accident on September 14, 1946, after he fell asleep at the wheel of his 1934 Ford. The car went over a cliff and overturned. At the end of his senior year, he missed his final examination in heat transfer; a washed-out bridge prevented him from getting to class. This left him one requirement short of a degree. On May 29, 1962, after his Mercury flight, the university granted him his Bachelor of Science degree because "his subsequent training as an astronaut more than made up for the deficiency in the subject of heat transfer."