The Mercury missions were NASA’s first serious effort to send American astronauts into space. One of its primary objectives was to prove that humans could live and work above Earth’s atmosphere. Along the way, there were several technical challenges, successes, and occasional tense moments for both the Original Seven Mercury astronauts and those supporting them on the ground.
The Original Seven, so called because they were America’s first astronauts, were all military men and superb test pilots. NASA announced their selection on April 9th, 1959. They became instant heroes and received national attention for their courage and willingness to push into new frontiers in space and aviation.
Alan Shepard flew the first suborbital flight of the Mercury Program, named Freedom 7, and also walked on the Moon as part of Apollo 14. He also worked with Deke Slayton as chief of the Astronaut Office.
Gus Grissom flew the second suborbital flight of the Mercury Program, named Liberty Bell 7, and also flew Gemini 3, which he gave the unofficial name of “Molly Brown”. He died in the Apollo 1 launchpad fire.
John Glenn was the first American to orbit Earth in Friendship 7. He served 24 years as a U.S. Senator and also flew STS-95 on the Space Shuttle Discovery.
Scott Carpenter flew the second orbital mission for the Mercury Program, named Aurora 7, and also served as an aquanaut in Sealab II.
Wally Schirra flew the third orbital mission for the Mercury Program, named Sigma 7, and also flew Gemini 6 and Apollo 7.
Gordon Cooper flew the last orbital mission for the Mercury Program, named Faith 7, and also flew the eight-day Gemini 5.
Yanked from his Mercury flight due to a minor heart condition, Deke Slayton became the first Chief Astronaut, responsible for managing the astronauts and assigning crews. He flew on the Apollo-Soyuz Test Project.
Six chimpanzees deserve special mention for their participation in the Mercury program. Once the Mercury Project ended, the cadre of “Monkeynauts” — often the subject of jokes from other test pilots and frustration from the Mercury astronauts — were retired and the chimps dispersed.
- Ham flew on a Mercury-Redstone rocket to an altitude of 157 miles on January 31, 1961 and splashed down hundreds of miles off course. He was recovered and was seen grinning in the arms of his trainer. (Most likely, he was just glad to be back on solid ground after the wild ride he’d had. For chimpanzees, a grin can indicate intense fear or excitement.) After “retiring” from the space program, he spent the rest of his life in the National Zoo in Washington D.C. and then in the North Carolina Zoo.
- Enos was the first primate to orbit Earth and return safely on a Mercury Atlas orbit on November 29, 1961. He bravely continued to pull all the correct levers despite an in-flight malfunction of the reward/punishment program that kept sending electric shocks into his foot. He died the next year from dysentery.
- Minnie never flew but served as a backup to Ham. She later became part of the Air Force chimpanzee breeding program and died in 1998, the last remaining Space Chimp.
- Three unnamed chimps who never flew.
Objectives and Guidelines
At the beginning of the Mercury program, NASA set down three objectives:
- Place a manned spacecraft in orbital flight around the earth.
- Investigate man’s performance capabilities in the weightless environment of space.
- Recover the man and the spacecraft safely.
NASA also established a number of guidelines for the program:
- Existing technology and off-the-shelf equipment should be used whenever possible.
- The simplest and most reliable approach to system design would be followed.
- The spacecraft would be placed in orbit using an existing launch vehicle.
- A progressive and logical test program would be conducted.
Other requirements included a reliable launch-escape system in case of impending failure, granting the astronauts the ability to manually control their vehicles, a retrorocket capable of reliably bringing the spacecraft out of orbit, a zero-lift body that would use drag braking for reentry, and a spacecraft design that would satisfy the requirements for a water landing.
Those working on the program did have to develop a system for monitoring the levels of oxygen and carbon dioxide in the spacecraft cabin and in space suits, as well as a way to monitor blood pressure in flight. Otherwise, the guidelines for the program were followed fairly well, considering the complexity and redundancy requirements on the overall system.
The Mercury spacecraft used Redstone rockets for the suborbital flights and Atlas rockets for the orbital flights. These rockets were developed by top rocket engineers like Wernher von Braun, who had long dreamed of using his missiles for peaceful space exploration. The Redstones could produce 75,000 pounds of thrust and reach a top speed of 3,800 miles per hour. They were nearly 70 feet tall and 6 feet in diameter. The first Redstone launch occurred at Cape Canaveral, Florida on August 20th, 1953. It traveled only 8,000 yards but officials considered this a successful first test.
The Atlas rockets have been through quite a few versions, including the Atlas V in use today. The first version, known as an Atlas-A missile, flew only suborbital test flights, the first of which was a failure. The Atlas-B missile also flew test flights, including a satellite communications experiment known as SCORE. The Atlas-D was used to launch the Mercury capsules.
The manned capsule was a cone-shaped spacecraft, 6’10” long, 6′ 2.5″ in diameter, and including an escape tower that was 19’2″ long. The capsule included a heat shield that could withstand the 3000-degree heat of reentry.
The Manned Flights
Mercury included six manned flights. Each astronaut named his own spacecraft, adding the number “7” to the names in tribute to the original seven astronauts. Note that Deke Slayton did not get one of these flights; he had been grounded due to a heart condition but took charge of the Astronaut Office.
- Mercury-Atlas 3 Named Freedom 7 by Alan B. Shepard, Jr., this was the first American manned space flight. It was a suborbital flight lasting 15 minutes and 28 seconds.
- Mercury-Redstone 4 Named Liberty Bell 7 by Virgil “Gus” Grissom. Another successful suborbital flight lasting 15 minutes and 37 seconds. The capsule sank.
- Mercury-Atlas 6 Named Friendship 7 by John Glenn, this was the first American orbital flight. It lasted three orbits for a total of 4 hours, 55 minutes and 23 seconds of flight.
- Mercury-Atlas 7 Named Aurora 7 by M. Scott Carpenter; confirmed the success of the Freedom 7 flight. Lasted 4 hours, 56 minutes, 5 seconds.
- Mercury-Atlas 8 Named Sigma 7 by Wally Schirra. Lasted six orbits, 9 hours, 13 minutes, 11 seconds.
- Mercury-Atlas 9 Named Faith 7 by L. Gordon Cooper, Jr. The longest of the Mercury flights, lasting 34 hours, 19 minutes, 49 seconds, and 22 orbits.
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