Scott Carpenter was the second American to orbit the Earth and the fourth American in space, following Alan Shepard, Gus Grissom, and John Glenn. Carpenter and Glenn are the last living members of the Mercury Seven as of September 2008.
On the eve of the Korean War, Carpenter was recruited by the USN's Direct Procurement Program (DPP), and reported to NAS Pensacola in the fall of 1949 for pre-flight and primary flight training. He earned his wings on April 19, 1951, in Corpus Christi, Texas. During his first tour of duty, on his first deployment, Carpenter flew Lockheed P2V Neptunes for Patrol Squadron Six on reconnaissance and ASW (anti-submarine warfare) missions during the Korean War. Forward-based in Adak, Carpenter then flew surveillance missions along the Soviet and Chinese coasts during his second deployment; designated as PPC (patrol plane commander) for his third deployment, Lt. (j.g.) Carpenter was based with his squadron in Guam.
Scott Carpenter was then appointed to the United States Naval Test Pilot School, class 13, at NAS Patuxent River in 1954. He continued at Patuxent until 1957, working as a test pilot in the Electronics Test Division; his next tour of duty was spent in Monterey, California, at the Navy Line School. In 1958, Carpenter was named Air Intelligence Officer for the USS Hornet.
After being chosen for Project Mercury in 1959, Carpenter served as backup pilot for John Glenn, who flew the first U.S. orbital mission aboard Friendship 7 in February 1962. When Deke Slayton was withdrawn on medical grounds from Project Mercury's second manned orbital flight, Carpenter was assigned to replace him. He flew into space on May 24, 1962, atop the Mercury-Atlas 7 rocket for a three-orbit science mission that lasted nearly five hours. His Aurora 7 spacecraft attained a maximum altitude of 164 miles and an orbital velocity of 17,532 miles per hour.
Working through five onboard experiments dictated by the flight plan, Carpenter helped among other things to identify the mysterious 'fireflies' (which he renamed 'frostflies,' as they were in reality particles of frozen liquid around the craft), first observed by John Glenn during MA-6. Carpenter was the first American astronaut to eat solid food in space.
Chris Kraft, directing the flight from Florida considered Carpenter's "mission the most successful to date; everything had gone perfectly except for some overexpenditure of fuel"
Unnoticed by ground control or pilot, however, this "overexpenditure of fuel" was caused by an intermittently malfunctioning pitch horizon scanner that would later malfunction at reentry. Still, NASA later reported that Carpenter had:
"exercised his manual controls with ease in a number of [required] spacecraft maneuvers and had made numerous and valuable observations in the interest of space science. . . . By the time he drifted near Hawaii on the third pass, Carpenter had successfully maintained more than 40 percent of his fuel in both the automatic and the manual tanks. According to mission rules, this ought to be quite enough hydrogen peroxide, reckoned Kraft, to thrust the capsule into the retrofire attitude, hold it, and then to reenter the atmosphere using either the automatic or the manual control system."
At the retrofire event, however, the pitch horizon scanner malfunctioned once more, forcing Carpenter to manually control his reentry ("The malfunction of the pitch horizon scanner circuit [a component of the automatic control system] dictated that the pilot manually control the spacecraft attitudes during this event. The PHS malfunction jerked the spacecraft off in yaw by 25 degrees to the right, accounting for 170 miles of the overshoot; the delay caused by the automatic sequencer required Carpenter to fire the retrorockets manually. This effort took two pushes of the override button and accounted for another 15 to 20 miles of the overshoot. The loss of thrust in the ripple pattern of the retros added another 60 miles, producing a 250-mile overshoot.
Forty minutes after splashdown, Carpenter was located in his life raft, safe and in good health, by Major Fred Brown, under the command of the Puerto Rico Air National Guard,, and recovered three hours later by the USS Intrepid.
Postflight analysis described the PHS malfunction as "mission critical" but noted that the pilot "adequately compensated" for "this anomaly . . . in subsequent inflight procedures., confirming that that backup systems—human pilots—could succeed when automatic systems fail.
Some 21st-century memoirs revived the simmering controversy over who or what, exactly, was to blame for the overshoot, suggesting, for example, that Carpenter was distracted by the science and engineering experiments dictated by the flight plan and by the well-reported fireflies phenomenon. Yet fuel consumption and other aspects of the vehicle operation were, during Project Mercury, as much, if not more, the responsibility of the ground controllers. Moreover, hardware malfunctions went unidentified, while organizational tensions between the astronaut office and the flight controller office — tensions that NASA did not resolve until the later Gemini and Apollo programs — may account for much of the latter-day criticism of Carpenter's performance during his flight.
Carpenter never flew another mission in space. After taking a leave of absence from the astronaut corps in the fall of 1963 to train for and participate in the Navy's Sealab program, Carpenter sustained a medically grounding injury to his left arm in a motorbike accident. After failing to regain mobility in his arm after two surgical interventions (in 1964 and 1967), Carpenter was ruled ineligible for spaceflight. He resigned from NASA in August 1967.
In 1962, Boulder community leaders dedicated Scott Carpenter Park in honor of native son turned Mercury astronaut. The Aurora 7 Elementary School, also in Boulder (at 3995 Aurora Ave.), was named for Carpenter's capsule.
In the 1983 film, The Right Stuff, Carpenter was played by Charles Frank. Although his appearance was relatively minor, the film played up Carpenter's friendship with John Glenn, as played by Ed Harris.