AFTER BEING CHOSEN FOR PROJECT MERCURY IN 1959, CARPENTER, ALONG WITH THE OTHER SIX ASTRONAUTS, OVERSAW THE DEVELOPMENT OF THE MERCURY CAPSULE. HE SERVED AS BACKUP PILOT FOR JOHN 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.
WHEN DEKE SLAYTON WAS WITHDRAWN ON MEDICAL GROUNDS FROM PROJECT MERCURY'S SECOND MANNED ORBITAL FLIGHT (WHICH SLAYTON WOULD HAVE NAMEDDELTA 7), CARPENTER WAS ASSIGNED TO REPLACE HIM. HE FLEW INTO SPACE ON MAY 24, 1962, ATOP THE MMERCURY ATLAS 7 ROCKET FOR A THREE-ORBIT SCIENCE MISSION THAT LASTED NEARLY FIVE HOURS. HISAURORA 7SPACECRAFT ATTAINED A MAXIMUM ALTITUDE OF 164 MILES (264 KM) AND AN ORBITAL VELOCITY OF 17,532 MILES PER HOUR