Project Mercury

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Project Mercury
Mercury-patch-info.png
Duration 1959–1963
Nationality US
Goal Orbital flight
Result Accomplished goal but no firsts
US flight firsts:
Astronauts
Crew size One
Rockets Atlas D, Redstone and Little Joe
Contractor McDonnell Aircraft (spacecraft)
Cost $1.71 billion (current prices)
Followers Gemini and Apollo
Rival Vostok program (Soviet)

Project Mercury was the first human spaceflight program of the United States led by its newly created space agency NASA. It ran from 1959 through 1963 with the goal of putting a human in orbit around the Earth, and doing it before the Soviet Union, as part of the early space race. It involved 7 astronauts flying a total of 6 solo trips. On 5 May 1961, Alan Shepard became the first American in space in a suborbital flight after the Soviet Union had put Yuri Gagarin into space and orbit one month earlier. John Glenn became the first American to reach orbit on 20 February 1962. He was the third person to do so, after Soviet Gherman Titov made a day-long flight in August 1961. When the project ended in May 1963, the Americans' NASA program was still behind the Soviet Space Program, but the gap was seen as closing. The race to the Moon began.

The space race started in 1957 by the launch of the Soviet satellite Sputnik I. This came as a shock to the American public and led to the creation of NASA to gather the efforts in space exploration already existing in the USA. After the launch of the first American satellite in 1958, manned space flight became the next goal. The spacecraft was produced by McDonnell Aircraft. It was cone shaped with room for one person together with supplies of water, food and oxygen for about one day in a pressurized cabin. It was launched from Cape Canaveral in Florida by modified military missiles, most importantly Atlas D, and had a rescue tower for protection from a failing rocket. The whole flight could be controlled from the ground through a network of tracking stations which also allowed communication with the astronaut. If necessary, the astronaut could override commands from the ground. For reentry into Earth's atmosphere, small rockets were used to bring the spacecraft out of its orbit. A heatshield would protect the spacecraft from the heat of reentry, and a parachute would slow the craft for a water landing. Here both astronaut and spacecraft were picked up by helicopter and brought to a ship.

From a slow start with humiliating mistakes, the Mercury Project became popular and the manned flights were followed by millions on radio and TV not only in United States, but around the world. Apart from the manned missions, Mercury had a total of 20 unmanned launches as a part of the development of the project. This also involved test animals, most famously the chimpanzees Ham and Enos. Mercury laid the groundwork for Project Gemini and the follow-on Apollo moon-landing program, which was announced a few weeks after the first manned flight. The astronauts went under the name Mercury Seven and they named their spacecraft with a "7" to the name. The project name was taken from Mercury, a Roman god. It is estimated to have cost $1.71 billion (current prices) and have involved the work of 2 million people.

Creation[edit]

Project Mercury was officially approved 7 October 1958 and publicly announced on 17 December.[1][2] Originally it was called Project Astronaut, but president Eisenhower thought that it gave too much attention to the pilot.[3] Instead the name Mercury was chosen from Greek-Roman mythology, which already lent name to rockets like Atlas and Jupiter[2] It absorbed military projects with the same aim such as the Air Force Man-in-Space-Soonest.[4][n 1]

Background[edit]

Following the end of World War II, a nuclear arms race evolved between the US and the Soviet Union to develop long-range missiles.[6] At the same time both sides also developed satellites for espionage.[7] Most of this took place in secret, therefore it came as a shock to the US public when the Soviet Union placed the first satellite into orbit in October 1957[8] and there was a growing fear in the US that it was falling behind.[7] A month later the Soviet launched a dog into orbit and though it was not retained it was obvious that they were striving at manned spaceflight.[9] Unable to tell the public about the progress of military space projects, president Eisenhower decided to create a civilian space agency NASA, based on NACA, a federal aeronautical research agency.[10] NASA should take care of civilian and scientific space exploration[11] and after having orbited an American satellite in 1958[12] the next goal became to put a man in space.

The limit of space was defined as an altitude of 62 mi (100 km)[13] and the only way to reach it was by rocket.[14] This created risks for the pilot, including explosion, subjection to high g-force and vibrations during lift off through the atmosphere.[15] In space, the pilot would experience zero gravity, a condition where he might suffer from disorientation.[16] In this altitude he had to be in a pressurized chamber or suit and supplied with fresh air.[17] Further possible risks were radiation from space[18] and micrometeoroids, from which the air would normally protect him.[19] At reentry to the denser part of the atmosphere, air friction would heat the spacecraft to more than 10,000 °F (5,540 °C).[20] All these obstacles, however, seemed possible to overcome. Experiences from satellites suggested that the risk from micrometeoroids was negligible.[21] As to the medical questions, experiments in the early 1950s with simulated weightlessness and high g-forces on humans together with experiments of sending animals to the limit of space gave the conclusion that problems could be overcome by known technology.[22] Finally, reentry was studied with the nuclear warhead of ballistic missiles.[23] From this, the best solution to the heating problem was found to be a blunt heatshield facing the direction of movement during reentry since it created a shock wave that let most of the heat flow around the spacecraft or warhead.[23]

Organization and facilities[edit]

Location of production and operational facilities of Project Mercury
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Wallops
Island
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Hampton
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Johnsville
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Cleveland
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Greenbelt
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C. Canaveral
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Huntsville
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St. Louis
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Alamogordo
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San Diego
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Los Angeles

T. Keith Glennan had been appointed administrator of NASA with Hugh L. Dryden (director of NACA) his deputy from the creation of the agency on 1 October 1958.[24] Glennan would report to the president through the National Aeronautics and Space Council.[11] The group responsible for project Mercury was NASA's Space Task Group[25] and the goals of the program were to orbit a manned spacecraft around Earth, investigate the pilot's ability to function in space and to recover both pilot and spacecraft safely.[26] Existing technology and off-the-shelf equipment should be used wherever practical, the simplest and most reliable approach to system design would be followed, an existing launch vehicle would be employed together with a progressive test program.[26] Spacecraft requirements included: a launch escape system to separate the spacecraft and its occupant from the launch vehicle in case of impending failure; attitude control for orientation of spacecraft in orbit; a retrorocket system to bring the spacecraft out of orbit; drag braking blunt body for atmospheric reentry; and landing on water.[26] To communicate with the spacecraft during an orbital mission a network had to be built.[27]

Twelve companies bid to build the Mercury spacecraft on a $20 million ($160 million) contract.[28] In January 1959, McDonnell Aircraft Corporation was chosen to be prime contractor for the spacecraft.[29] Two weeks earlier, North American Aviation, based in Los Angeles, was awarded a contract to Little Joe a small rocket for development of its launch escape system.[30] The World Wide Tracking Network for communication between ground and spacecraft during a flight was awarded Western Electric Company.[31] Redstone rockets for suborbital launches were manufactured at Huntsville, Alabama by Chrysler Corporation[32] and Atlas rockets at Convair San Diego, California.[33] For manned launches the Atlantic Missile Range at Cape Canaveral Air Force Station in Florida was made available by the USAF.[34] This was also the site of Mercury Control Center while the computing center of the communication network was in Goddard Space Center, Maryland.[35] Little Joe developing rockets were launched at Wallops Island, Virginia.[36] Astronaut training took place at Langley Research Center, Lewis Flight Propulsion Laboratory, Cleveland, and Naval Air Development Center in Johnsville.[37] Langley wind tunnels[38] together with a rocket sledge track at Holloman Air Force Base at Alamogordo were used for aerodynamic studies.[39] Both Navy and Air Force aircraft were made available for development of the landing system of the spacecraft,[40] and Navy ships and Navy and Marine Corps helicopters were made available for recovery.[n 2] South of Cape Canaveral the town of Cocoa Beach boomed.[42] From here, 75,000 people watched the first American orbital flight being launched in 1962.[42]

  • Wallops Island, 1961

  • Mercury Control Center, Cape Canaveral, 1963

Spacecraft[edit]

The principal designer of the Mercury spacecraft was Max Faget who started research for manned spaceflight during the time of NACA.[43] The spacecraft was 10.8 feet (3.3 m) long and 6.0 feet (1.8 m) wide; with the launch escape system added, the overall length was 25.9 feet (7.9 m).[44] With 100 cubic feet (2.8 m3) of habitable volume, the spacecraft was just large enough for the single crew member.[45] Inside were 120 controls: 55 electrical switches, 30 fuses and 35 mechanical levers.[46] The heaviest spacecraft, Mercury-Atlas 9, weighed fully loaded 3,000 pounds (1,400 kg).[47] Its outer skin was made of René 41 a nickel alloy able to withstand high temperatures.[48]

The spacecraft was shaped as a cone with a neck in the narrow end.[44] It had convex base, which was the heatshield (2).[49] It was composed of an aluminum honeycomb structure covered with multiple layers of fiberglass.[50] Strapped to it was the retropack (1)[51] which had its name from three rockets meant to brake the spacecraft for reentry.[52] Between these were three minor rockets for separating the spacecraft from the launch vehicle at insertion into orbit.[53] The straps that held the package could be severed when it was no longer needed.[54] Next to the heatshield came the pressurized crew compartment (3).[55] This contained the astronaut strapped to his couch with the instruments in front of him and his back to the heatshield.[56] Underneath the seat was the environmental control system, which supplied him with oxygen and heat.[57] The system also cleaned the air of CO2, vapor and odors, as well as (on orbital flights) collect urine.[58][n 3] The recovery compartment (4)[60] at the narrow end of the spacecraft contained three parachutes: one drogue to stabilize free fall and two main parachutes of which only one was used, the other was a reserve.[61] Between the heatshield and the inner wall of the crew compartment there was a landing skirt which was deployed by letting down the heat shield before landing.[62] On top of the recovery compartment was the antenna section (5)[63] containing antennas for communication with earth and scanners for guiding the orientation of the spacecraft.[64] Attached to it was a flap used to ensure the right heatshield-first direction during reentry.[65] A launch escape system (6) was mounted to the narrow end of the spacecraft.[66] In case of failure during the first minutes of launch it would fire a solid fuel rocket for a second to bring the spacecraft free of the launch vehicle so it could deploy its parachute and land at sea.[67]

  • 1. Retropack. 2. Heatshield. 3. Crew compartment. 4. Recovery compartment. 5. Antenna section. 6. Launch escape system.

  • Retropack: Retrorockets with red posigrade rockets

  • Landing skirt principles

Role of pilot[edit]

Mercury space suit

The astronaut sat with his back to the heat shield, in a seat which was molded from his body for maximum support. As a safety measure he wore a pressure suit with its own oxygen supply, which would also cool him.[68] An atmosphere of pure oxygen was easier to control than one with the same composition as air at ground level.[69] To put out fire the astronauts had to empty the compartment of oxygen.[58] Should air pressure of the compartment fail due to puncturing by micrometeoroids or other reasons, astronauts could still make an emergency return to Earth relying on their suit for survival.[70][58] The astronauts normally flew with the visor up which meant that the suit was not inflated.[58] With the visor down and the suit inflated, the astronaut could only reach the side and bottom panels where vital buttons and handles accordingly were placed.[71] Cabin pressure was equivalent to an altitude of 18,000–25,000 feet (5,500–7,600 m).[71] Across his chest electrodes were placed to record his heart rhythm, a cuff could take his blood pressure and a rectal thermometer his temperature (this would be replaced by a mouth thermometer on the last flight).[72] Data from these was sent to the ground during the flight.[68] For orientation, he could look through the window in front of him or from a screen connected to a periscope which could be turned 360°.[73] The astronaut normally drank water and ate food pellets.[74]

In orbit the spacecraft could be rotated in three directions: along the longitudinal axis of the spacecraft (roll), from left to right as seen from the astronaut (yaw) and up-down as seen from the astronaut (pitch).[75] Movement was created by thrusters (jets) using peroxide as a fuel.[76] The movements and other functions of the spacecraft could be controlled in three ways: remotely from the ground when passing a ground station, automatically guided by its own instruments, or manually by the astronaut, who could replace or override the two other methods.[77] In his left hand he held an abort handle that could activate the launch escape system if the automatic system failed.[78] The astronauts had taken part in the development of the spacecraft and they required the manual control by the astronaut together with the window in front of the astronaut.[79] John Glenn's manual attitude adjustments during the first orbital flight were an example of the value of such control.[80]

Development and production[edit]

Spacecraft production at McDonnell

Spacecraft design was modified three times by NACA/NASA in 1958–59 before the final shape was found.[81] At the time of bidding for spacecraft contractor in November 1958, it was the third approach named C which was suggested by NASA and which the winning bid was based on.[82] This was change to the final figuration called D after having failed a test flight in July 1959.[83] The shape of the heatshield had been found earlier in the 1950s by experiments with ballistic missiles, which had shown that a blunt heatshield would create a shock wave which would lead most of the heat around the spacecraft.[84] To further protect against heat, either a heat sink or an ablative material could be added to the shield.[85] The heat sink would remove heat by the flow of the air inside the shock wave, where as the ablative heatshield would remove heat by a controlled evaporation of the ablative material.[86] After unmanned tests the latter was chosen for the manned flights.[87] Apart from the capsule design a rocketplane similar to the existing X-15 was considered.[88] This approach was still too far from being able to make a spaceflight and consequently dropped.[89][n 4] The heatshield and the stability of the spacecraft were tested in wind tunnels[38] and later in flight.[92] The launch escape system was developed by unmanned flights.[93] An alternative concept for landing system involving the use of a glider instead of a parachute was considered but never got into use.[94]

The spacecraft were produced at McDonnell Aircraft, St. Louis, Missouri in clean rooms and tested the same place in vacuum chambers.[95] They had close to 600 subcontractors for instance Garrett AiResearch for the Environmental Control System.[29][57] Final quality control and preparations of the spacecraft were made at Hangar S at Cape Canaveral.[96][n 5] NASA ordered 20 production spacecraft, numbered 1 through 20.[29] Five of the 20, Nos. 10, 12, 15, 17, and 19, were not flown.[98] Spacecraft No. 3 and No. 4 were destroyed during unmanned test flights.[98] Spacecraft No. 11 sank[98] and was recovered from the bottom of the Atlantic Ocean after 38 years.[99] Some spacecraft were modified after initial production (refurbished after launch abort, modified for longer missions, etc.)[n 6] A number of Mercury boilerplate spacecraft (made from non-flight materials or lacking production spacecraft systems) were also made by NASA and McDonnell Aircraft.[102] They were designed and used to test spacecraft recovery systems and escape tower.[103] McDonnell also supplied the project's function trainers for the astronauts.[104]

  • Development in spacecraft design, 1958–59

  • Experiment with boilerplate spacecraft, 1959

Launch vehicles[edit]

1. Mercury-Atlas. 2. Mercury-Redstone. 3. Little Joe

The Mercury program used two launch vehicles for manned missions.[105][n 7] Most important was Atlas LV-3B or Atlas D, a 2-stage liquid fuel rocket for orbital flight.[106] It was developed by Convair for the Air Force in the mid-1950s[107] and was fuelled with liquid oxygen (LOX) and kerosene.[106] It was 67 feet (20 m) in itself and with the spacecraft and the launch escape system (including the adapter that held both to the launch vehicle) its total height was 95 feet (29 m).[108] The first stage was a booster skirt with two thrusters using liquid fuel from the sustainer stage.[106] This together with the bigger sustainer stage gave it sufficient power to launch an orbital mission.[106] Both stages fired from lift-off until staging of the booster; the sustainer through an opening in the booster.[106] After staging the sustainer stage continued alone. The sustainer also steered the rocket by a movable thruster guided by gyroscopes.[109] Smaller rockets were added on its side for precise control of maneuvers.[106] The hull was paper thin made of stainless steel and had to be kept under constant internal pressure by fuel or helium in order not to collapse.[110] This meant that the airframe of the launch vehicle could be reduced to 2% of the weight of the fuel.[110] The Atlas D rocket required extra strengthening in order to handle the increased weight of the Mercury spacecraft beyond that of the nuclear warheads they were designed for.[53] Its internal guidance system also had to be moved accordingly to its greater length.[53] The Titan missile was also considered for later Mercury missions but did not get ready in time.[111][n 8] The Atlas was flown to Cape Canaveral and transported to the launch pad on a dolly.[113] At the launch pad, rocket and dolly were lifted to a vertical position by the service tower and the Atlas was then held by clamps to the launch pad.[114][113]

The other launch vehicle was the Mercury-Redstone Launch Vehicle which was 83 feet (25 m) (spacecraft and escape system included) tall 1-stage launch vehicle used for suborbital (ballistic) flights.[115] It had a liquid-fueled engine that burned alcohol and liquid oxygen producing about 75,000 pounds of thrust which was not enough for orbital missions.[115] It was a descendant of the German V-2,[32] and developed for the army in the early 1950s and modified for Project Mercury by removing the war head and adding a collar for supporting the spacecraft together with material for dampening vibrations during launch.[116] Its rocket motor was produced by North American Aviation and its direction could be altered during flight through the atmosphere by its fins.[32] Both Atlas D and the Redstone launch vehicles contained an automatic abort sensing system which allowed them to abort a launch by firing the launch escape system if something went wrong.[117] The Jupiter rocket, a relative of the Redstone, was originally considered for the suborbital launch vehicle, but was replaced by the Redstone in July 1959 due to budget constraints.[118][119]

A smaller launch vehicle (55 feet (17 m) long) called Little Joe which carried a Mercury spacecrafts with an escape tower mounted on it was used for unmanned test of the launch escape system.[120][121] Especially it was to test the system at a point called max-q, at which air pressure against the spacecraft peaked making separation of launch vehicle and spacecraft the most difficult.[122] It was also the point at which the astronaut was subjected to the heaviest vibrations.[123] Little Joe had a solid-fuel propellant and was designed in 1958 by NACA for suborbital manned flight but redesigned for Mercury to simulate the flight of Atlas D.[93] It was produced by North American Aviation.[120] It was not able to change direction, instead its flight depended on the angle in which it was launched.[124] Its maximum altitude was 100 mi (160 km) fully loaded.[125] A Scout launch vehicle was used for a single flight intended to evaluate the tracking network; however, it failed and was destroyed from the ground shortly after start.[126]

  • Mounting of spacecraft on Little Joe airframe at Wallops Island

  • Unloading Atlas at Cape Canaveral

  • Erection of Redstone at Launch Complex 5

  • Atlas on launch pad at Launch Complex 14

  • Launch Complex 14 just before launch (service tower rolled aside). Preparations for launch were made at blockhouse.


Astronauts[edit]

Left to right: Grissom, Shepard, Carpenter, Schirra, Slayton, Glenn and Cooper, 1962

NASA announced the selected seven astronauts – known as the Mercury Seven – on 9 April 1959,[127] these were:[128]

Shepard became the first American in space by making a suborbital flight in May 1961.[129] He went on to fly in the Apollo program.[130] Gus Grissom, who became the second American in space, also participated in the Gemini and Apollo programs, but died in January 1967 during a pre-launch test for Apollo 1.[131] Glenn became the first American to orbit the Earth in February 1962, then quit NASA and went into politics.[132] Deke Slayton was grounded in 1962, but remained with NASA and flew on the Apollo-Soyuz Test Project in 1975.[133] Gordon Cooper became the last to fly in Mercury and made its longest flight, and also flew a Gemini mission. [134] Carpenter's Mercury flight was his only trip into space.

One of the astronauts' tasks was publicity; they gave interviews to the press and visited project manufacturing facilities to speak with those who worked on Project Mercury.[135] To make their travels easier they requested and got jet fighters for personal use.[136] The press was especially fond of John Glenn, who was considered the best speaker of the seven.[137] They sold their personal stories to Life Magazine which portrayed them as patriotic, God-fearing and good family fathers.[138] Life was also allowed to be at home with the families while the astronauts were in space.[138] During the project, Grissom, Carpenter, Cooper, Schirra and Slayton stayed with their families at or near Langley Air Force Base; Glenn lived at the base and visited his family in Washington DC on weekends. Shepard lived with his family at Naval Air Station Oceana in Virginia.[139]

Selection and training[edit]

It was envisaged that the pilot could be any man or woman willing to take a personal risk.[140] On President Eisenhower's insistence, however, the first Americans to venture into space were drawn from a group of 508 military test pilots.[141] This excluded women, since there were no female military test pilots.[3] It also excluded NACA's X-15 pilot and later astronaut Neil Armstrong, since he was a civilian.[3][n 9] It was further stipulated that candidates should be between 25 and 40 years old, not taller than 5 ft 11 in (1.80 m), and hold a college degree in science or engineering.[3] The college degree requirement excluded NACA's X-1 pilot Chuck Yeager, the first person to exceed the speed of sound.[143] He later became a critic of the project, ridiculing especially the use of monkeys.[143][n 10] Joseph Kittinger, a stratosphere balloonist, met all the requirements but preferred to stay in his contemporary project.[143] Some other potential candidates declined because they did not believe that manned spaceflight had a future beyond project Mercury.[143] From the original 508, 110 candidates were selected for interview, and from the interviews 32 were selected for further physical and mental testing.[145] Their health, vision, and hearing were examined, together with their tolerance to noise, vibrations, g-forces, personal isolation, and heat.[146] In a special chamber, they were tested to see if they could perform their tasks under confusing conditions.[146] The candidates had to answer more than 500 questions about themselves and describe what they saw in different images.[146] Jim Lovell, later astronaut in Gemini and Apollo, did not pass the physical tests.[143] After these tests it was intended to narrow the group down to six astronauts but in the end it was decided to keep seven.[147]

The astronauts went through a training program covering some of the same exercises that were used in selection.[37] They simulated the g-force profiles of launch and reentry in a centrifuge at the Naval Air Development Center, and were taught special breathing techniques necessary when subjected to more than 6 g.[136] Weightlessness training took place in aircraft, first on the rear seat of a two seated fighter and later inside converted and padded cargo aircrafts.[148] They practiced gaining control of a spinning spacecraft in a machine at the Lewis Flight Propulsion Laboratory called the Multi-Axis Spin-Test Inertia Facility (MASTIF), by using an attitude controller handle simulating the one in the spacecraft.[149] A further measure for finding the right attitude in orbit was star and Earth recognition training in planetaria and simulators.[150] Communication and flight procedures were practiced in flight simulators, first together with a single assistance and later together with Mission Control Center.[151] Recovery was practiced in pools at Langley, and later at sea with frogmen and helicopter crews.[152]

Mission profile[edit]

Suborbital mission profile; the dashed line indicates the region of zero gravity

Project Mercury had two kinds of missions: suborbital, and orbital.[25][153] In the suborbital mission, a Redstone rocket lifted the spacecraft for 2 min 30 seconds to an altitude of 32 nautical miles (59 km),[154] separated from it and let it continue on a ballistic curve.[155] Though not necessary for re-entry because orbtal speed had not been attained, retrorockets were fired, and the spacecraft landed in the Atlantic ocean.[156] Orbital missions also landed in the Atlantic, and a flotation collar, not ready for suborbital missions, was fastened around the spacecraft after landing.[157] The suborbital mission took 15 minutes, had an apogee altitude of 102–103 nautical miles (189–191 km), and a downrange distance of 262 nautical miles (485 km).[134][158]

Preparations for a mission started a month in advance with the selection of primary and back-up astronaut; they would practice together for the mission.[159] For three days prior to launch the astronaut had gone through a special diet to minimize his need for defecating during the flight.[160] on the morning of the trip he typically ate a steak breakfast.[160] After having sensors applied to his body and being dressed in the pressure suit, he started breathing pure oxygen to prepare him for the atmosphere of the spacecraft.[161] He arrived at the launch pad, took the elevator up the launch tower and entered the spacecraft two hours before launch.[162][n 11] Once the astronaut was secured inside, the hatch was bolted, the launch area evacuated and the mobile tower rolled back.[163] After this, the launch vehicle was filled with liquid oxygen.[163] The entire procedure of preparing for launch and launching spacecraft into orbit followed a time table called countdown. It started a day in advance with a pre-count in which all systems of the launch vehicle and spacecraft were checked. After that followed a 15 hours hold during which pyrotechnics were installed. Then came the main countdown which for orbital flights started 6½ hours before launch (T – 390 min), counted backwards to launch (T = 0) and then forward until insertion (T + 5 min).[162][n 12]

Orbital mission profile; A-D is launch; E-K is re-entry and landing

On an orbital mission, rocket engines were ignited 4 seconds before lift-off. The launch vehicle was held to the ground by clamps and then released when sufficient thrust was built up at lift-off (A).[165] After 30 seconds of flight, the point of maximum dynamic pressure against the vehicle was reached, at which point the astronaut felt heavy vibrations.[166] The booster engines were cut off and released after 2 min 10 sec[162] (B). At this point, the launch escape system was no longer needed, and was separated from the spacecraft by its jettison rocket (C).[52][n 13] The launch vehicle moved gradually to a horizontal attitude during launch until, at an altitude of 87 nautical miles (161 km), the spacecraft was inserted into orbit (D).[168] This happened after 5 min 10 sec[162] in a direction pointing east whereby the spacecraft would gain speed from the rotation of earth.[169][n 14] Here the spacecraft fired the three posigrade rockets for 1 second to separate it from the launch vehicle.[171][n 15] Just before orbital insertion g-load peaked at 8 g at cut-off of rocket engine (6 g for suborbital flight).[166][173] In orbit, the spacecraft automatically turned 180°, pointed the retropackage forward and its nose 14.5° downward (E) and kept this attitude for the rest of the orbit phase,[174][n 16] it was necessary for communication with ground.[175] Once in orbit it was not possible to change the trajectory except by initiating reentry.[176] Each orbit would typically take 88 minutes to complete.[177] The lowest point of the orbit called perigee was at the point where orbit entered and was about 87 nautical miles (161 km) the highest called apogee was on the opposite side of Earth and was about 150 nautical miles (280 km).[158] When leaving orbit, the spacecraft retrorockets fired for 10 seconds each (F).[171] in a sequence where one started 5 seconds after the other.[178] During reentry (G), the astronaut would experience about 8 g (11–12 g on a suborbital mission).[179] The temperature around the heatshield rose to 3,000 °F (1,650 °C)[180] and at the same time there was a 2 minute radio black out due to ionization of the air around the spacecraft.[54] After re-entry, a small, drogue parachute (H) was deployed at 21,000 ft (6,400 m) for stabilization of the fall.[64] The main parachute (I) was deployed at 10,000 ft (3,000 m) starting with a narrow opening that opened fully in a few seconds to lessen the strain on the lines.[181] Just before hitting the water, the landing bag inflated from behind the heat shield to reduce the force of impact (J).[181] Upon landing the parachutes were released.[61] An antenna (K) was raised and sent out signals that could be traced by ships and helicopters.[61] Further, a dye was spread around the spacecraft to make it easier seen from the air.[61][n 17] Frogmen brought in by helicopters inflated a collar around the craft to keep it upright in the water.[157] The recovery helicopter hooked onto the spacecraft and the astronaut blew the escape hatch to exit the capsule.[60] He was then hoisted aboard the helicopter that finally brought both him and the spacecraft to a ship.[n 18]

Personnel supporting a Mercury mission counted 18,000,[184] about 15,000 of these were associated with recovery.[185][n 19] Most of the others followed the spacecraft from the World Wide Tracking network a chain of 18 stations around equator based on a network for unmanned satellites and ready in 1960.[187] It collected data from the spacecraft and providing two way communication between astronaut and ground.[188] Each station had a range of 700 nautical miles (1,300 km) and a pass typically lasted 7 minutes.[189] Mercury astronauts on the ground would take part of the Capsule Communication or Cap Com who communicated with the astronaut in orbit.[190] Occasionally this communication was broadcast on live TV while the spacecraft was passing over USA[191] Data were sent to the ground, processed at Goddard Space Center and relayed to Mercury Control Center at Cape Canaveral.[192] In the Control Center the data were displayed on boards on each side of a map of the world,[175] which showed the position of the spacecraft,[175] its ground track and the place it could land in an emergency within the next 30 minutes.[175][n 20]

  • Mercury manned launches

  • Astronaut in orbit (Mercury-Atlas 6)

  • A look inside the Mercury Control Center, Cape Canaveral, Florida. Dominated by the control board showing the position of the spacecraft above ground

    Inside Control Center at Cape Canaveral (Mercury-Atlas 8)

  • Recovery seen from helicopter (Mercury-Redstone 3)

Flights[edit]

On 12 April 1961 the Soviet cosmonaut Yuri Gagarin became the first person in space on an orbital flight.[195] Alan Shepard became the first American in space on a suborbital flight three weeks later, 5 May 1961.[129] John Glenn, the third Mercury astronaut to fly, became the first American to reach orbit on February 20, 1962, but only after the Soviets had launched a second cosmonaut, Gherman Titov, into a day long flight in August 1961.[196] Three more Mercury orbital flights were made, ending on May 16, 1963 with a day-long, 22 orbit flight.[134] However, the Soviet Union ended its Vostok program the next month, with the human spaceflight endurance record for the 82-orbit, almost 5-day Vostok 5 flight.[197]

Manned[edit]

All manned Mercury flights were successful.[198] The main medical problems met were simple personal hygiene, and post-flight symptoms of low blood pressure.[184] The launch vehicles had been tested by unmanned flights, this is the reason why mission names do not start with 1.[199] Following a pilot tradition, the astronauts gave their spacecraft a name, all with a "7" to the end.[52][128] Times are UTC or local time + 5 hours.

Mission Call-sign Pilot Launch time Launch
site		 Duration Orbits Apogee
mi (km)		 Perigee
mi (km)		 Max. velocity
mph (km/h)		 Recovery Ship Miss
mi (km)		 Remarks[200]
Mercury-Redstone 3 Freedom 7 Shepard 14:34 on 5 May 1961 LC-5 15 m 28 s 0 117 (188) — 5,134 (8,262) USS Lake Champlain (carrier)[16] 3.5 (5.6) First American in space.[129]
Mercury-Redstone 4 Liberty Bell 7 Grissom 12:20 on 21 July 1961 LC-5 15 m 37 s 0 118 (190) — 5,168 (8,317) USS Randolph (carrier)[201] 5.8 (9.3) Spacecraft sank before recovery when hatch unexpectedly blew off[202][n 21]
Mercury-Atlas 6 Friendship 7 Glenn 14:47 on 20 February 1962 LC-14 4 h 55 m 23 s 3 162 (261) 100 (161) 17,544 (28,234) USS Noa (frigate)[203] 46 (74) First American in orbit.[204] Retropack retained during re-entry.[205][n 22]
Mercury-Atlas 7 Aurora 7 Carpenter 12:45 on 24 May 1962 LC-14 4 h 56 m 15 s 3 167 (269) 100 (161) 17,549 (28,242) USS Farragut (destroyer)[207] 248 (400) Carpenter replaced Deke Slayton.[208]
Mercury-Atlas 8 Sigma 7 Schirra 12:15 on 3 October 1962 LC-14 9 h 13 m 11 s 6 176 (283) 100 (161) 17,558 (28,257) USS Kearsarge (carrier)[209] 4.6 (7.4) The flight closest to plan.[210] Carried out maneuvering tests[211]
Mercury-Atlas 9 Faith 7 Cooper 13:04 on 15 May 1963 LC-14 1 d 10 h 19 m 49 s 22 166 (267) 100 (161) 17,547 (28,239) USS Kearsarge[80] 5.0 (8.1) First American in space for over a day.[212] Last American solo mission.[n 23]
President Kennedy, first lady Jacqueline, vice president Johnson and two more watching the flight of the first American manned mission, 1961

Mercury-splash-down.png

← Freedom 7 watched on TV in the White House
→ USS Kearsarge with crew spelling Mercury-9
/
Cape Canaveral
Hawaii
City locator 23.svg
Freedom 7
City locator 23.svg
Liberty Bell 7
City locator 23.svg
Friendship 7
City locator 23.svg
Aurora 7
City locator 23.svg
Sigma 7
City locator 23.svg
Faith 7
 USS Kearsarge with crew spelling Mercury-9

Unmanned[edit]

The unmanned flights belonged to four programs: Little Joe, Mercury-Atlas, Mercury-Redstone and Mercury-Scout.[128] They were used to develop launch vehicles, launch escape system, spacecraft and tracking network.[199] The Little Joe program used 7 airframes for 8 flights of which 3 were successful. Little Joe 6, the second flight of the program, got its name because it was inserted into the program after the first 5 airframes had been allocated.[214][160] The Soviet Vostok program had 9 test flights from January 1960 till March 1961 where successful orbital flights with dogs demonstrated their capability of launching a man.[197]

Mission Launch Duration Objective Result Remarks[215]
Little Joe 1 21 August 1959 20 s Test of launch escape system during flight. Failure Due to electrical malfunction the escape tower ignited ½ hour before launch and took the spacecraft with it leaving the rocket on the ground.[216]
Big Joe 1 9 September 1959 13 m 00 s Test of heat shield and Atlas / spacecraft interface Success/Failure Belonged to Mercury Atlas program.[128] Recovered byUSS Strong (DD-758) 2,407 km southeast of Cape Canaveral.[217] Altitude: 65 mi (105 km) Qualified ablative heatshield.[92]
Little Joe 6 4 October 1959 5 m 10 s Test of spacecraft aerodynamics and integrity Partial success No additional tests[218]
Little Joe 1A 4 November 1959 8 m 11 s Test of launch escape system during flight with boiler plate capsule Partial success The rescue tower rocket ignited 10 seconds too late.[219] Recovered by USS Opportune 11.5 mi (18.5 km) southeast of Wallops Island.[220]
Little Joe 2 4 December 1959 11 m 6 s Primate escape at high altitude Success Carried Sam, a rhesus macaque.[219] Recovered by USS Borie (DD-704) 194 miles (312 km) southeast of Wallops Island, Virginia; altitude: 53 mi (85 km).[221]
Little Joe 1B 21 January 1960 8 m 35 s Maximum-q abort and escape with primate with boiler plate capsule Success Carried Miss Sam[222] Altitude: 9 mi (15 km)
Beach Abort 9 May 1960 1 m 31 s Test of the off-the-pad abort system Success
Mercury-Atlas 1 29 July 1960 3 m 18 s Test of Mercury spacecraft / Atlas combination Failure Collapsed and exploded while passing through max-q[223] To save weight the airframe had been made thinner since Big Joe, which led to the collapse. Next Atlas was strengthened by a temporary solution while the rest were made from the same specifications as Big Joe[224]
Little Joe 5 8 November 1960 2 m 22 s First test escape system with a production Mercury spacecraft Failure Clamp holding the spacecraft was deflected by air pressure; due to this and an incorrect wiring, the escape tower ignited too early but failed to separate spacecraft from launch vehicle.[39] Clamp was subsequently tested by rocket sledge[39] Altitude: 10 miles (16 km)[225]
Mercury-Redstone 1 21 November 1960 2 s Qualify production spacecraft at max-q Failure Engine shutdown caused by improper separation of electrical cables;[226] vehicle rose 4 in (10 cm) and settled back on pad. Escape tower was jettisoned and parachutes deployed.[227]
Mercury-Redstone 1A 19 December 1960 15 m 45 s Qualify spacecraft / Redstone combination. Success First flight of Mercury / Redstone. Recovered by USS Valley Forge[228] Altitude: 130 mi (210 km)[97]
Mercury-Redstone 2 31 January 1961 16 m 39 s Carry the chimpanzee Ham on suborbital flight Success Recovered by USS Donner (LSD-20)[229] 422 miles (679 km) southeast of Cape Canaveral; altitude: 157 mi (253 km)[230]
Mercury-Atlas 2 21 February 1961 17 m 56 s Qualify Mercury/Atlas interface Success Recovered by USS Donner[231] 1,432 miles (2,305 km) southeast of Cape Canaveral.
Little Joe 5A 18 March 1961 23 m 48 s Second test of escape system with a production Mercury spacecraft Partial success Tower fired 14 seconds too soon; it failed to separate spacecraft from rocket.[232]
Mercury-Redstone BD 24 March 1961 8 m 23 s Redstone development test flight Success Last Redstone test flight. (BD: Booster Development)[233]
Mercury-Atlas 3 25 April 1961 7 m 19 s Orbital (upgraded from suborbital) flight with robot astronaut[234][235][n 24] Failure Was aborted when it did not go into orbit; boiler plate capsule recovered and reused in Mercury-Atlas 4[237]
Little Joe 5B 28 April 1961 5 m 25 s Third test of escape system with a production Mercury spacecraft Success Concluded Little Joe program
(May–July, 1961: manned suborbital flights)
Mercury-Atlas 4 13 September 1961 1 h 49 m 20 s Test of environmental control system with robot astronaut in orbit Success Completed one orbit and sent data to the ground; first orbital flight of the project.[238] Recovery by USS Decatur (DD-936) 176 miles (283 km) east of Bermuda.[239]
Mercury-Scout 1 1 November 1961 44 s Test of Mercury tracking network Failure Was aborted after malfunction of guidance system;[240] results of Mercury-Atlas 4 and Mercury-Atlas 5 were used instead[241]
Mercury-Atlas 5 29 November 1961 3 h 20 m 59 s Test of environmental control system in orbit with a primate Success Chimpanzee Enos completed a two-orbit flight performing tasks of pulling a lever on a given signal.[242][n 25] Last Mercury-Atlas test flight. Recovery by USS Stormes (DD-780)[244] 255 miles (410 km) southeast of Bermuda.[245]
(February 1962 – May 1963: manned orbital flights)

  • Little Joe 1B with Miss Sam, 1960

  • Mercury-Redstone 1: launch escape tower lift-off after 4'' launch, 1960

  • Mercury-Redstone 2: Ham, 1961

  • Mercury-Atlas 5: Enos, 1961

Canceled[edit]

Suborbital flights were planned for all of the original intended 6 astronauts making Mercury-Redstone 8 the last.[246]

Mission Call—sign Pilot Planned Launch Cancellation Remarks
Mercury-Jupiter 1 July 1, 1959[247]
Mercury-Jupiter 2 Chimpanzee First Quarter, 1960 July 1, 1959[247] Proposed maximum dynamic pressure qualifying test for a capsule.[248]
Mercury-Redstone 5 Glenn (likely) March 1960[246] August 1961[249]
Mercury-Redstone 6 April 1960[246] July 1961[250]
Mercury-Redstone 7 May 1960[246]
Mercury-Redstone 8 June 1960[246]
Mercury-Atlas 10 Freedom 7-II Shepard October 1963 June 13, 1963 In November 1962 intended to be a three-day mission with extra supplies attached to the heatshield. By January 1963 changed to a one day back up mission for Mercury-Atlas 9. Was cancelled after the success of the latter.[251]
Mercury-Atlas 11 Grissom Fourth Quarter, 1963 October 1962 Intended to be a one-day mission[252]
Mercury-Atlas 12 Schirra Fourth Quarter, 1963 October 1962 Intended to be a one-day mission[253]

Impact and legacy[edit]

Ticker tape parade for Gordon Cooper, 1963

The project was 22 months delayed counting from the start until the first orbital mission.[184] It had a dozen prime contractors, 75 major subcontractors, and about 7200 third-tier subcontractors, whom together employed two million persons.[184] An estimate of its cost made by NASA in 1969 gave $392.6 million ($1.71 billion adjusted for inflation[254]), broken down as follows: Spacecraft: $135.3 million, launch vehicles: $82.9 million, operations: $49.3 million, tracking operations and equipment: $71.9 million and facilities: $53.2 million.[255][256]

Today the Mercury Project is commemorated as the first manned American space program.[257] It did not win the race against the Soviet but gave back prestige and was scientifically a successful precursor of later programs such as Gemini, Apollo and Skylab.[258][n 26] Back in the 1950s even experts doubted that manned spaceflight was possible.[n 27] Still when John F. Kennedy was elected president, many including him had doubts about the project.[261] As president he chose to support Mercury few months before Freedom 7,[262] which became a great public success.[263][n 28] Afterwards, a majority supported manned spaceflight and within few weeks Kennedy announced the Apollo program for a manned mission to the moon before the end the 1960s.[267] The six astronauts, who flew, were awarded medals,[268] drove in parade and two of them were invited to address a joint session of the US Congress.[269] As a response to the selection criteria, which ruled out women, a private project was founded in which 13 women pilots successfully underwent the same tests as the men in Project Mercury.[270] It was named Mercury 13 by the media[271][n 29] Despite this effort, NASA did not select female astronauts until 1978 for the Space Shuttle.[272]

In 1964, Project Mercury got a monument near Launch Complex 14 at Cape Canaveral featuring a metal logo combining the symbol of mercury with the number 7.[273] In 1962, the US Post Office honored the Mercury-Atlas 6 flight with the Project Mercury commemorative stamp, the first US postal issue to depict a manned spacecraft.[274] The stamp first went on sale in Cape Canaveral, Florida on 20 February 1962, the same day as the Project Mercury launch was putting the first US astronaut into orbit.[274] On 4 May 2011, the US Postal Service released a stamp commemorating the 50th anniversary of Freedom 7, the first manned flight of the project.[275] On film the project have been portrayed in The Right Stuff a 1983 American award nominated adaptation of Tom Wolfe's 1979 book by the same name.[276] On 25 February 2011, the Institute of Electrical and Electronic Engineers, the world's largest technical professional society, awarded Boeing Company as successor to McDonnell Aircraft a Milestone Award for important inventions which debuted on the Mercury spacecraft.[277][n 30]

Displays[edit]

Patches[edit]

Commemorating patches were designed by entrepreneurs after the Mercury program to satisfy collectors.[278][n 32]

  • Freedom 7 insignia.gif
  • Mercury 4 - Patch.jpg
  • Mercury 6 - Patch.jpg
  • Aurora 7 patch.png
  • Mercury-8-patch.png
  • Mercury 9 - Patch.jpg

Graphics[edit]

Astronauts assignments[edit]

  • Mercury 7-astronauts assignments. Schirra had most flights: 3; Glenn, though being the first to leave NASA, had the last: a Space Shuttle in 1998.[279] Shepard was the only to walk on the Moon.

Tracking network[edit]

  • Ground track and tracking stations for Mercury-Atlas 8. Spacecraft starts from Cape Canaveral in Florida and moves east; each new orbit-track is displaced to the left due to the rotation of the Earth. It moves between latitudes 32.5° north and 32.5° south.[280] Key: 1–6: orbit number. Yellow: launch. Black dot: tracking station. Red: range of station; Blue: landing.

Spacecraft cutaway[edit]

  • Interior of spacecraft

  • The three axes of rotation for the spacecraft: yaw, pitch and roll

Control panels[edit]

  • Control panels from Friendship 7.[281] The panels changed between flights, among others the periscope screen that dominates the center of these panels was dropped later.

Notes[edit]

  1. ^ Man in Space Soonest was first part of a four phase Moon landing program to finish in 1965, cost a total of $1.5 billion ($12 billion) and being boosted by a "Super Titan".[5]
  2. ^ NASA's planning for recovery operations in the summer of 1960 was, according to the Navy, asking for the deployment of the whole Atlantic Fleet and might have cost more than the entire Mercury program.[41]
  3. ^ On the first suborbital flight there was no urine collection where as on the other the astronaut had a reservoir added to the space suit[59]
  4. ^ The rocket plane approach to manned space flight was pursuit in the Air Force Dyna-Soar project, cancelled in 1963[90] At the end of the 60s NASA resumed the concept in what would become the Space Shuttle.[91]
  5. ^ Test and rework of Mercury-Redstone 2 at the Hangar required 110 days.[97]
  6. ^ They received a letter designation after their number, examples 2B, 15B.[100] Some were modified twice; for example, spacecraft 15 became 15A and then 15B.[101]
  7. ^ The word booster is sometimes used for launch vehicle like in Mercury-Redstone Booster Development. With the latter as an exception, the word booster is only used for the first stage of the Mercury-Atlas in this article.
  8. ^ Instead, it was used for the Gemini program which followed.[112]
  9. ^ Armstrong left the Navy in 1952, and became a Lieutenant, Junior Grade, in the US Naval Reserve. He remained in the reserve for eight years until he resigned his commission in 1960.[142]
  10. ^ John Glenn did not have a college degree either, but used influential friends to make the selection committee accept him.[144]
  11. ^ Inside the spacecraft the other astronauts had usually prepared a practical joke, such as a sign saying "No handball playing".[163]
  12. ^ Countdown was controlled from the blockhouse at the Launch Complex until 2 min. before launch then it was transferred to Mission Control Center. The countdown of the last 10 sec. before launch would be given to the astronaut by one of the others and included on TV transmissions which had already started.[164]
  13. ^ In the event of a launch abort before this point, the launch escape system would fire its main rocket for one second, pulling the spacecraft and astronaut away from the launch vehicle and a possible explosion.[67] At this point, the spacecraft could be separated from the launch vehicle and land using its parachute.[167]
  14. ^ The direction of insertion was east and slightly to the north, this meant that on at three orbit flight the tracking network was utilized best possible and a landing could take place in the North Atlantic Ocean.[170]
  15. ^ The sustainer would disintegrate and fall down; after the launch of Friendship 7 a part of the sustainer was found in South Africa.[172]
  16. ^ The 34° angle on the illustration is the angle at retrofire.[174]
  17. ^ Radar chaff and a sofar bomb which could be detected by the ship's hydrophone were eliminated as unnecessary after the first orbital flight.[182]
  18. ^ It was also possible to exit the capsule through the nose cylinder;[27] only Carpenter did this.[64] In the two last missions the spacecraft with the astronaut inside was dragged by a boat to the ship, hoisted aboard and where upon the astronauts left through the hatch.[183]
  19. ^ T.J. O'Malley pushed the button to launch Glenn while site Manager and Launch Conductor at Complex 14, Calvin D. Fowler, pushed the button to launch Carpenter, Schirra and Cooper.[186][full citation needed]
  20. ^ The World Wide Tracking Network went on to serve the following space programs until it was replaced by a satellite relay system in the 1980s[193] Mission Control Center was moved from Cape Canaveral to Houston in 1965.[194]
  21. ^ It was recovered in 1999.[99]
  22. ^ Launch of Friendship 7 was postponed repeatedly during two months; a frustrated politician compared the spacecraft-Atlas combination to "a Rube Goldberg device on top of a plumber's nightmare".[206]
  23. ^ Likely to be so according to Alexander & al.[213]
  24. ^ A machine that produced the same heat, vapor and CO2 as an astronaut[236]
  25. ^ Was given a reward in the form a banana pellet or a punishment in the form of mild electrical shocks depending on whether or not he gave the right response to a given signal; by mistake he was sometimes given shocks on right answers.[243]
  26. ^ International rules required that a pilot must land safely with the spacecraft; in reality, Gagarin landed separately by parachute; however, the Soviet Union did not admit this until 1971 when their claim was no longer in danger of being challenged.[259]
  27. ^ In May 1957, five months before Sputnik I, the president of McDonnell, the later prime contractor, predicted that manned spaceflight would not take place before 1990.[260]
  28. ^ Along the roads in USA, drivers stopped to follow Freedom 7 on the radio. Later, 100 millions saw or listened to Friendship 7, the first orbital flight, on TV or radio.[264] The launch of Sigma 7 and Faith 7 were relayed live via communication satellite to television audiences in Western Europe.[265] Two of the three major US networks covered Sigma 7 minute-by-minute, the rest were showing the opening of the World Series.[266]
  29. ^ It gave Soviet leader Khrushchev the idea of launching the first women cosmonaut Valentina Tereshkova on 16 June 1963.[213]
  30. ^ Boeing received the award in recognition of Project Mercury's pioneering "navigation and control instruments, autopilot, rate stabilization and control, and fly-by-wire systems."[277]
  31. ^ The stamp was issued February 20, 1962, the day of John Glenn's flight in Friendship 7. This one has a First Day of Issue postmark from Cape Canaveral post office.
  32. ^ The only patches the Mercury astronauts wore, were the NASA logo and a name tag.[278] Each manned Mercury spacecraft was painted black and decorated with a flight insignia, its call-sign an American flag and the words United States.[52]

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