@Mark Ollig
In late September 1962, astronaut Walter “Wally” Schirra Jr. conducted a 6.5-hour Mercury-Atlas 8 (MA-8) simulation with NASA’s worldwide tracking network, serving as the dress rehearsal for the actual flight.
Sixty-three years ago today, Oct. 3, 1962, the MA-8 spacecraft Sigma 7 launched from Cape Canaveral, FL.
At 39 years old, Schirra piloted the Sigma 7 spacecraft attached atop an Atlas LV-3B booster that generated about 368,000 pounds of thrust at liftoff.
The Atlas LV-3B was adapted from the Atlas D missile, America’s first intercontinental ballistic missile (ICBM).
It stood nearly 95 feet tall, measured 10 feet in diameter, and weighed about 260,000 pounds at liftoff when fueled with kerosene and liquid oxygen.
About two minutes after liftoff, the rocket dropped its two booster engines, and the sustainer engine carried Sigma 7 into Earth orbit.
Schirra maintained radio contact with mission controllers at the Mercury Control Center (MCC), led by Flight Director Christopher C. Kraft and supported by ground teams.
The MCC was at Cape Canaveral Air Force Station (now Cape Canaveral Space Force Station), FL, where all Project Mercury flights were coordinated.
NASA’s Mission Control began operations from Houston, TX, in 1965.
From orbit, Schirra spoke with astronaut capsule communicators (CapComs) at the MCC, which included astronaut Donald K. “Deke” Slayton.
The original Mercury Seven astronauts were John H. Glenn Jr., Alan B. Shepard Jr., Virgil I. “Gus” Grissom, Malcolm Scott Carpenter, Leroy Gordon Cooper Jr., Donald K. “Deke” Slayton, and Walter M. “Wally” Schirra Jr.
At liftoff, Schirra reported, “Okay, Deke, the clock has started. Roll program started. Smooth. Real smooth.”
Slayton replied, “Roger, Sigma 7. Read you loud and clear. That was a mighty fine lift-off.”
The Sigma 7 mission tested how well Schirra and his spacecraft worked together during a lengthier flight than previous Mercury missions.
It also checked NASA’s worldwide tracking system for future missions.
The Mercury spacecraft was a small, cone-shaped vehicle designed for one astronaut.
It measured six feet, 10 inches in length and six feet, two-and-a-half inches in diameter, and with the launch escape tower attached, the stack stood approximately 26 feet tall.
Built by McDonnell Aircraft Corporation and weighing about 3,200 pounds, the MA-8 spacecraft featured the Attitude Stabilization and Control System (ASCS) for attitude control.
During the flight, the Attitude Stabilization and Control System (ASCS) automatically maintained the spacecraft’s steady state and held its position for most of the mission.
Spacecraft attitude and stability during flight could also be controlled manually through a fly-by-wire system, where a hand controller sent electrical signals to the control electronics, which pulsed small reaction-control thrusters.
The ASCS was built by Minneapolis-Honeywell Regulator Company (now Honeywell) in Minneapolis.
The spacecraft used both alternating and direct current power sources, with backups, and cockpit indicators alerted the astronaut to any electrical faults.
The cabin panel layout consisted of 120 controls, including 55 electrical switches and 30 fuses.
NASA’s Goddard Space Flight Center in Greenbelt, MD, operated the worldwide tracking network and used two IBM 7090 computers running in real time to compute Sigma 7’s trajectory and predictions. An IBM 709 at the Bermuda station provided additional support.
Results were routed to the Mercury Control Center and tracking stations worldwide to support voice and telemetry links with the spacecraft.
NASA’s Project Mercury network for MA-8 connected 21 ground stations and tracking ships located around the world.
Sigma 7 used line-of-sight very high frequency (VHF) and ultra-high frequency (UHF) voice communications, including a 296.8 megahertz (MHz) VHF channel.
It also carried a high-frequency (HF) voice backup for long-range contact and a recovery beacon for post-landing operations.
Sigma 7 flew at altitudes between 100 and 176 miles, averaging 17,558 miles per hour.
After completing the sixth orbit and covering nearly 144,000 miles in just more than nine hours, a US record at the time, Schirra prepared the spacecraft for reentry back to Earth.
Sigma 7 landed in the central Pacific Ocean about 275 miles northeast of Midway Island and about 5.1 miles from the recovery ship, the aircraft carrier USS Kearsarge.
Schirra called it a “textbook flight” and said he chose the name Sigma 7, with sigma (the Greek letter Σ) meaning “sum,” to highlight the engineering sum behind the mission, with “7” acknowledging the original Mercury Seven astronauts.
Wally Schirra Jr. is the only astronaut to have flown all three NASA mission programs, Mercury (Sigma 7, Oct. 3, 1962), Gemini (Gemini 6A, Dec. 15, 1965), and Apollo (Apollo 7, Oct. 11, 1968).
During a NASA oral-history interview Dec. 1, 1998, Wally Schirra recalled meeting then-Vice President Hubert H. Humphrey, who chaired the National Space Council, during Gemini 6 training in 1965.
Schirra related how Humphrey asked whether they could be heard outside the soundproofed Gemini simulator and was told they could not.
Humphrey then climbed into the right-hand seat of the Gemini docking simulator, asked to be awakened in five minutes, and fell asleep.
When awakened, Humphrey asked, “What were we doing?”
Schirra said he was a fan of Humphrey’s from that day forward and called it “a fun story about a nice man.”
Walter Marty “Wally” Schirra Jr. died May 3, 2007, at age 84.
