Project Mercury

Project Mercury was the United States' first manned spaceflight program. It ran from 1959 through 1963 with the goal of putting a man in orbit around the Earth. Early planning and research was carried out by NACA, while the program was officially carried out by the newly created NASA. The name comes from Mercury, a Roman mythological god who is often seen as a symbol of speed. Mercury is also the name of the innermost planet of the solar system, which revolves around the sun faster than any other, hence the image of speed, although Project Mercury had no other connection to that planet.

The Mercury program cost $1.5 billion. See NASA Budget.

Spacecraft

It was said that the Mercury spacecraft were not ridden, they were worn, because of their extremely small size - at 1.7 cubic metres in volume, the capsule was just large enough for the single crew member. Inside were 120 controls: 55 electrical switches, 30 fuses and 35 mechanical levers. The spacecraft was designed by Max Faget and NASA's Space Task Group.

During the launch phase of the mission, the Mercury spacecraft and astronaut were protected from launch vehicle failures by the Launch Escape System. The LES consisted of a solid fuel, 52,000 lbf (231 kN) thrust rocket mounted on a tower above the spacecraft. In the event of a launch abort, the LES fired for 1 second, pulling the Mercury spacecraft away from a defective launch vehicle. The spacecraft would then descend on its parachute recovery system. After booster engine cutoff (BECO), the LES was no longer needed and was separated from the spacecraft by a solid fuel, 800 lbf (3.6 kN) thrust jettison rocket that fired for 1.5 seconds.

To separate the Mercury spacecraft from the launch vehicle, the spacecraft fired three small solid-fuel, 400 lbf (1.8 kN) thrust rockets for 1 second. These rockets are called the Posigrade rockets.

The spacecraft was only equipped with attitude control thrusters - after orbit insertion and before retrofire they could not change their orbit. There were three sets of high and low powered automatic control jets and separate manual jets - one for each axis (yaw, pitch, and roll), supplied from two separate fuel tanks - one automatic and one manual. The pilot could use any one of the three thruster systems and fuel them from either of the two fuel tanks to provide spacecraft attitude control.

The Mercury spacecraft were designed to be totally controllable from the ground in the event that the space environment impaired the pilot's ability to function.

The spacecraft had three solid-fuel, 1000 lbf (4.5 kN) thrust retrorockets that fired for 10 seconds each. One was sufficient to return the spacecraft to earth if the other two failed. The firing sequence (known as ripple firing) required firing the first retro, followed by the second retro five seconds later (while the first was still firing). Five seconds after that, the third retro fired (while the second retro was still firing).

There was a small metal flap at the nose of the spacecraft called the "spoiler". If the spacecraft started to reenter nose first (another stable reentry attitude for the capsule), airflow over the "spoiler" would flip the spacecraft around to the proper, heatshield-first reentry attitude. During reentry, the astronaut would experience about 4 g-forces.

Initial designs for the spacecraft suggested the use of either beryllium heat-sink heat shields or an ablative shield. Extensive testing settled the issue - ablative shields proved to be reliable (so much so that the initial shield thickness was safely reduced, allowing a lower total spacecraft weight), easier to produce (at that time, beryllium was only produced in sufficient quantities by a single company in the US) and cheaper.

NASA ordered 20 production spacecraft, numbered 1 through 20, from McDonnell Aircraft Company, St. Louis, Missouri. Five of the twenty spacecraft, #10, 12, 15, 17, and 19, were not flown. Spacecraft #3 and #4 were destroyed during unmanned test flights. Spacecraft #11 sank and was recovered from the bottom of the Atlantic Ocean after 38 years. Some spacecraft were modified after initial production (refurbished after launch abort, modified for longer missions, etc) and received a letter designation after their number, examples 2B, 15B. Some spacecraft were modified twice; for example, spacecraft 15 became 15A and then 15B.

A number of boilerplate spacecraft (mockup/prototype/replica spacecraft, made from non-flight materials or lacking production spacecraft systems and/or hardware) were also made by NASA and McDonnell Aircraft and used in numerous tests, including launch.

Boosters

The Mercury program used three boosters:

• Little Joe - 8 suborbital robotic flights, 2 carrying monkeys. Launch escape system tests.
• Redstone - 4 suborbital robotic flights, 1 carrying a chimpanzee; 2 piloted suborbital flights.
• Atlas - 4 suborbital robotic flights; 2 orbital robotic flights, 1 carrying a chimpanzee; 5 piloted orbital flights.

Little Joe was used to test the escape tower and abort procedures. Redstone was used for suborbital flights, and Atlas for orbital ones. Starting in October, 1958, Jupiter missiles were also considered as suborbital launch vehicles for the Mercury program, but were cut from the program in July, 1959 due to budget constraints. The Atlas boosters required extra strengthening in order to handle the increased weight of the Mercury capsules beyond that of the nuclear warheads they were designed to carry. Little Joe was a solid-propellant booster designed specially for the Mercury program. The Titan missile was also considered for use for later Mercury missions, however the Mercury program was terminated before these missions were flown. The Titan was used for the Gemini program which followed Mercury.

The Mercury program used a Scout booster for a single flight, Mercury-Scout 1, which launched a small satellite intended to evaluate the worldwide Mercury Tracking Network. The rocket was destroyed by the Range Safety Officer after 44 seconds of flight.

Unpiloted flights

The program included 20 robotic launches. Not all of these were intended to reach space and not all were successful in completing their objectives. Four of these flights included non-human primates, starting with the fifth flight (1959) which launched a Rhesus macaque named Sam (after the Air Force's School of Aviation Medicine). The Mercury program's complete roster of non-human space-farers is given below:

• Sam, a Rhesus macaque, launched December 4, 1959 on Little Joe 2 to 85 km altitude.

• Miss Sam, a Rhesus macaque, launched January 21, 1960 on Little Joe 1B to 15 km altitude.

• Ham, a chimpanzee, launched January 31, 1961 on Mercury-Redstone 2 for a suborbital flight.

• Enos, a chimpanzee, launched November 29, 1961 on Mercury-Atlas 5 for a 2-orbit flight.

Piloted Flights

Astronauts

The first Americans to venture into space were drawn from a group of 110 military pilots chosen for their flight test experience and because they met certain physical requirements. Seven of those 110 became astronauts in April 1959. Six of the seven flew Mercury missions (Deke Slayton was removed from flight status due to a heart condition). Beginning with Alan Shepard's Freedom 7 flight, the astronauts named their own spacecraft, and all added "7" to the name to acknowledge the teamwork of their fellow astronauts

Mercury had seven prime astronauts, all former military test pilots, known as the Mercury Seven. NASA announced the selection of these astronauts on April 9, 1959.

• Malcolm Scott Carpenter, USN (1925-)
• Leroy Gordon "Gordo" Cooper, Jr., USAF (1927-2004)
• John Herschel Glenn. Jr., USMC (1921-) First American to orbit the earth.
• Virgil Ivan "Gus" Grissom, USAF (1926-1967)
• Walter Marty Schirra, Jr., USN (1923-)
• Alan Bartlett Shepard, Jr., USN (1923-1998) First American in space.
• Donald Kent "Deke" Slayton, USAF (1924-1993) Grounded in 1962 due to irregular heartbeat, reinstated in 1972 and later flew on the Apollo-Soyuz Test Project in 1975.

Piloted Mercury launches

Mercury Flight insignias

Flight patches that purport to be patches from various Mercury missions are available to the public. In reality, these patches were designed by private entrepreneurs long after the Mercury program ended. When genuine flight patches were created by crews in the Gemini program, this caused a public demand for Mercury flight patches, which was filled by these private entrepreneurs. The only patches the Mercury astronauts wore were the NASA logo and a name tag. Each manned Mercury spacecraft, however, was decorated with a flight insignia. These are the genuine Mercury flight insignias.

Miscellaneous

The Mercury astronauts trained, in part, at NASA Langley Research Center in Hampton, Virginia, under Flight Surgeon William K. Douglas and Keith G. Lindell (COL, USAF). Several bridges throughout the city bear the name of the Mercury astronauts, and U.S. Route 258, a major north-south route in the cities of Hampton and Newport News is named Mercury Boulevard, honoring the Mercury program.

The names of five of the Mercury astronauts are also commemorated in the popular 1960s TV show Thunderbirds. In the series, Jeff Tracy, the founder of the fictional International Rescue organisation, is a millionaire ex-astronaut who has named his five sons -- Scott, Virgil, Alan, John and Gordon -- after the real-life Mercury astronauts.

Further reading

• Chris Kraft, Flight: My Life in Mission Control. Factual, written by one of the pivotal figures in America's space programme, whose involvement ran from the early days of NACA through the formation of NASA, Mercury, Gemini, Apollo, ASTP, Skylab and the early days of Shuttle operations. ISBN 0-452-28304-3
• Gene Kranz, Failure is Not an Option. Factual, from the standpoint of a chief flight controller during the Mercury, Gemini, and Apollo space programs. ISBN 0-7432-0079-9
• Tom Wolfe, The Right Stuff. Sentimental, from the test pilot, and later the astronaut viewpoint, more journalistic than a literal history (Wolfe interviewed many of those involved).
• Schirra, Grissom, Glenn, Slayton, Shepherd, Carpenter, Cooper, We Seven. (ISBN B00005X54G); Simon & Schuster - 1962. Factual; a collection of articles written by the seven Mercury astronauts describing events from their points of view.
• James M. Grimwood, This New Ocean: A History of Project Mercury
• James M. Grimwood, Project Mercury - A Chronology
• Mae Mills Link, Space Medicine In Project Mercury
• Results of the first US manned orbital space flight - Feb 20, 1962 (Friendship 7) NASA report - (PDF format)
• Results of the second u.s. manned orbital space flight, May 24, 1962 (Aurora 7) NASA report - (PDF format)
• This New Ocean: A History of Project Mercury - NASA report (PDF format)
• Chronology of Project Mercury - NASA report (PDF format)

See also

• Man In Space Soonest
• Vostok program
• Splashdown
• Mercury 13
• Mercury 7

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