Wright Aerospace Medical Laboratory. Carpenter was considered the most physically fit by his peers; he had the lowest body fat, scored highest on the treadmill and cycling tests, and was able to hold his breath the longest. This was despite the fact that he had smoked a pack of cigarettes a day since joining the Navy in 1943, and did not quit smoking until 1985. NASA's Charles J. Donlan called Carpenter's home on April 3, 1959, to inform him that he had been one of the seven men selected. Rene answered; Carpenter was on Hornet, but she could reach him. Carpenter called Donlan from a wharfside pay phone to accept the offer. Hornet skipper, Captain Marshall W. White, refused to release Carpenter until the Chief of Naval Operations, Admiral Arleigh Burke was able to persuade him. The identities of the seven were announced at a press conference at Dolley Madison House in Washington, D.C., on April 9, 1959: Carpenter, Gordon Cooper, John Glenn, Gus Grissom, Wally Schirra, Alan Shepard, and Deke Slayton. The magnitude of the challenge ahead of them was made clear a few weeks later, on the night of May 18, 1959, when the seven astronauts gathered at Cape Canaveral to watch their first rocket launch, of an SM-65D Atlas, which was similar to the one that was to carry them into orbit. A few minutes after liftoff, it spectacularly exploded, lighting up the night sky. The astronauts were stunned. Shepard turned to Glenn and said: "Well, I'm glad they got that out of the way." Mercury-Atlas 7 Carpenter, along with the other six Mercury astronauts, oversaw the development of the Mercury spacecraft. Each had a specialty; Carpenter's was the onboard navigational equipment. He served as backup pilot on Mercury-Atlas 6 for Glenn, who flew the first U.S. orbital mission aboard Friendship 7 in February 1962. Carpenter, serving as capsule communicator on this flight, can be heard saying "Godspeed, John Glenn" on the recording of Glenn's liftoff. The next mission was a second manned orbital flight to be flown by Slayton (in a capsule he would have named Delta 7), but he was suddenly grounded for an atrial fibrillation. Carpenter was assigned to replace him instead of Slayton's backup, Schirra, as Carpenter had more training time in the simulators. In contrast to Glenn's flight, Mercury-Atlas 7 was planned as a scientific mission rather than an engineering one. After