Project Mercury

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This article is about Project Mercury. For other uses of the term Mercury, please see Mercury (disambiguation).
McDonnell Mercury capsule
Mercury Capsule2.png
The Mercury capsule
Role: Suborbital and orbital spaceflight
Crew: one, pilot
Height: 11.5 ft 3.51 m
Diameter: 6.2 ft 1.89 m
Volume: 60 ft3 1.7 m3
Weights (MA-6)
Launch: 4,265 lb 1,935 kg
Orbit: 2,986 lb 1,354 kg
Post Retro: 2,815 lb 1,277 kg
Reentry: 2,698 lb 1,224 kg
Landing: 2,421 lb 1,098 kg
Rocket engines
Retros (solid fuel) x 3: 1,000 lbf ea 4.5 kN
Posigrade (solid fuel) x 3: 400 lbf ea 1.8 kN
RCS high (H2O2) x 6: 25 lbf ea 108 N
RCS low (H2O2) x 6: 12 lbf ea 49 N
Endurance: 34 hours 22 orbits
Apogee: 175 miles 282 km
Perigee: 100 miles 160 km
Retro delta v: 300 mph 483 km/h

Project Mercury was the United States of America' 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.


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.


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:

Mission Rocket Call Sign Launch Date Launch Time Duration Remarks
Mercury-Jupiter Jupiter (missile) N/A N/A N/A N/A Cancelled in July, 1959 - Proposed suborbital launch vehicle for Mercury. Not flown.
Little Joe 1 Little Joe LJ-1 Aug 21, 1959 N/A 00d 00h 00 m 20s Test of launch escape system during flight.
Big Joe 1 Atlas 10-D Big Joe 1 Sep 9, 1959 N/A 00d 00h 13 m Test of heat shield and Atlas / spacecraft interface.
Little Joe 6 Little Joe LJ-6 Oct 4, 1959 N/A 00d 00h 05 m 10s Test of capsule aerodynamics and integrity.
Little Joe 1A Little Joe LJ-1A Nov 4, 1959 N/A 00d 00h 08 m 11s Test of launch escape system during flight.
Little Joe 2 Little Joe LJ-2 Dec 4, 1959 N/A 00d 00h 11 m 06s Carried Sam the monkey to 85 kilometres in altitude.
Little Joe 1B Little Joe LJ-1B Jan 21, 1960 N/A 00d 00h 08 m 35s Carried Miss Sam the monkey to 9.3 statute miles (15 kilometres) in altitude.
Beach Abort Launch escape system Beach Abort May 9, 1960 N/A 00d 00h 01 m 31s Test of the Off-The-Pad abort system.
Mercury-Atlas 1 Atlas MA-1 Jul 29, 1960 13:13 UTC 00d 00h 03 m 18s First flight of Mercury spacecraft and Atlas Booster.
Little Joe 5 Little Joe LJ-5 Nov 8, 1960 N/A 00d 00h 02 m 22s First flight of a production Mercury spacecraft.
Mercury-Redstone 1 Redstone MR-1 Nov 21,1960 N/A 00d 00h 00 m 02s Launched 4 inches (100 mm). Settled back on pad due to electrical malfunction.
Mercury-Redstone 1A Redstone MR-1A Dec 19, 1960 N/A 00d 00h 15 m 45s First flight of Mercury spacecraft and Redstone booster.
Mercury-Redstone 2 Redstone MR-2 Jan 31, 1961 16:55 UTC 00d 00h 16 m 39s Carried Ham the Chimpanzee on suborbital flight.
Mercury-Atlas 2 Atlas MA-2 Feb 21, 1961 14:10 UTC 00d 00h 17 m 56s Test of Mercury spacecraft and Atlas Booster.
Little Joe 5A Little Joe LJ-5A Mar 18, 1961 N/A 00d 00h 23 m 48s Test of the launch escape system during the most severe conditions of a launch.
Mercury-Redstone BD Redstone MR-BD Mar 24, 1961 17:30 UTC 00d 00h 8 m 23s Redstone Booster Development - test flight.
Mercury-Atlas 3 Atlas MA-3 Apr 25, 1961 16:15 UTC 00d 00h 07 m 19s Test of Mercury spacecraft and Atlas Booster.
Little Joe 5B Little Joe AB-1 Apr 28, 1961 N/A 00d 00h 05 m 25s Test of the launch escape system during the most severe conditions of a launch.
Mercury-Atlas 4 Atlas MA-4 Sep 13, 1961 14:09 UTC 00d 01h 49 m 20s Test of Mercury spacecraft and Atlas Booster. Completed 1 orbit.
Mercury-Scout 1 Scout MS-1 Nov 1, 1961 15:32 UTC 00d 00h 00 m 44s Test of Mercury tracking network.
Mercury-Atlas 5 Atlas MA-5 Nov 29, 1961 15:08 UTC 00d 03h 20 m 59s Carried Enos the Chimpanzee on a two orbit flight.

Piloted flights


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.

Mission Callsign Rocket Designation Pilot Launch Date Launch Time Duration Remarks
Mercury-Redstone 3 Freedom 7 Redstone MR-3 Shepard May 5, 1961 14:34 UTC 00d 00h
15 m 28s
First American to make a suborbital flight into space.
Mercury-Redstone 4 Liberty Bell 7 Redstone MR-4 Grissom July 21, 1961 12:20 UTC 00d 00h
15 m 37s
Second suborbital flight. Capsule sank before recovery when hatch unexpectedly blew off.
Mercury-Atlas 6 Friendship 7 Atlas MA-6 Glenn February 20, 1962 14:47 UTC 00d 04h
55 m 23s
First American to orbit the Earth (for a total of 3 orbits). Capsule's retropack retained during re-entry due to concerns about heatshield.
Mercury-Atlas 7 Aurora 7 Atlas MA-7 Carpenter May 24, 1962 12:45 UTC 00d 04h
56 m 15s
3 orbits. Reentered off-target by 402 km. Pilot Carpenter replaced Deke Slayton.
Mercury-Atlas 8 Sigma 7 Atlas MA-8 Schirra October 3, 1962 12:15 UTC 00d 09h
13 m 11s
Carried out engineering tests. 6 orbits.
Mercury-Atlas 9 Faith 7 Atlas MA-9 Cooper May 15, 1963 13:04 UTC 01d 10h
19 m 49s
First American in space for over a day. Last American to fly into space solo and orbit (since then many American X-15 pilots and the pilots of SpaceShipOne have flown past the 100km "space" plateau and returned to earth without orbiting...). 22 orbits.
Mercury 10 Freedom 7-II Atlas MA-10 Shepard N/A N/A N/A Intended to be a 3-day mission in October, 1963. Cancelled June 13, 1963.

Mercury flight insignias

Flight patches really 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.


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.

See also