Forty-eight years ago this month, Mercury Astronaut Walter M. Schirra, Jr. orbited the Earth six (6) times in his Mercury spacecraft code-named Sigma 7. The near-perfect 9-hour spaceflight was the United States’ third manned orbital mission flown within a period of eight (8) months.
Project Mercury was United States’ first manned spaceflight program. This historic pioneering space effort helped lay the foundation for America’s quest for the Moon. A total of six (6) missions (2 sub-orbital and 4 orbital) was flown between May of 1961 and May of 1963.
The Mercury Spacecraft measured 11.5 feet in length and had a diameter of 6.2 feet. Orbital weight was roughly 3,000 pounds. With a cockpit volume of only 60 cubic feet, an astronaut’s corporeal fit inside the spacecraft was exceedingly tight. Vehicle entry and egress was a real shoe-horning process. It is not complete hyperbole to say that, once inside, an astronaut wore, more than rode in, the Mercury space vehicle.
Despite its dimunitive size, the Mercury Spacecraft was an able spacefaring ship. Indeed, it was configured with a complete suite of life support, navigation, attitude control, communications, deboost, recovery and thermal protection systems. Aided by a vast national mission support team, recovery force, and world-wide tracking system, the Mercury spaceflight effort was entirely successful in establishing America in space.
America’s first astronauts were known as the Mercury Seven. History records their names; Shepard, Grissom, Glenn, Carpenter, Schirra, Cooper and Slayton. In the tense 1960’s Space Race with the Soviet Union, these men were indeed America’s Single-Combat Warriors immortalized by writer Tom Wolfe in his classic, The Right Stuff.
Mercury-Atlas No. 8 (MA-8) was the fifth Mercury mission. Whereas the two (2) previous flights had been three (3) orbit missions, MA-8 was scheduled to orbit the Earth six (6) times. The focus would be on spacecraft operations instead of space science. The intent was to verify that the Mercury spacecraft could be cleared for an orbital mission duration of at least 24 hours on the very next flight
As was the custom for a Mercury astronaut, Schirra personally named his orbital steed. As such, Schirra chose the name Sigma 7. The term Sigma, the Greek mathematical symbol for summation, signified a summation or culmination of flight experience and engineering development that led to a mature Mercury Spacecraft system. The numeral 7 represented the Mercury Seven.
The MA-8 mission began with lift-off from Cape Canaveral’s LC-14 at 12:15:12 UTC on Wednesday, 03 October 1962. The Atlas D launch vehicle placed Schirra into a 152.8-nm x 86.9-nm orbit. Once in orbit, Schirra quickly got down to business. This included tracking the Atlas booster, maneuvering the spacecraft, observing and photographing the Earth, and conducting various scientific experiments.
Schirra did a particularly good job at conserving the precious supply of Reaction Control System (RCS) fuel. One of the MA-8 objectives had been to do so. In fact, Schirra conserved fuel even more efficiently than planned. Other than an annoying and uncomfortable spacesuit heating problem that occurred several times, the entire MA-8 mission was what Schirra would ultimately call “textbook”.
MA-8 retro-fire occurred at 21:07:12 UTC. During the reentry, the automatic rate stabilization system damped spacecraft pitch and yaw oscillations. Drogue and main parachute deployment took place at 40,000 feet and 15,000 feet, respectively. Splashdown in the Pacific Ocean occurred 1,200 nm northwest of Hawaii at 21:28:22 UTC.
The success of MA-8 paved the way to Gordon Cooper’s historic 22-orbit, 34-hour MA-9 mission in May of 1963. The Gemini and Apollo Programs would soon follow. Wally Schirra would play a big part in both. He commanded the historic Gemini 6 orbital rendezvous mission in December of 1965. Schirra also went on to command the critical Apollo 7 mission in October of 1968.
Wally Schirra was the only member of the Mercury Seven to orbit the Earth in Mercury, Gemini and Apollo spacecraft.