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Museum Pieces: NASA's Project Mercury [1]
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Date: 2025-03-04
Project Mercury was America’s entry into the Space Race and was intended to put a human into space before the Soviet Union did.
"Museum Pieces" is a diary series that explores the history behind some of the most interesting museum exhibits and historical places.
Mercury Spaceship 15B, on display at the Smithsonian Udvar-Hazy Center. It was never flown.
The Soviet launch of the Sputnik satellite in October 1957 caused a near-panic in the United States and led to desperate calls to “catch up”. President Eisenhower responded by establishing the National Aeronautics and Space Administration (NASA) in 1958, and just a few months later the agency announced “Project Mercury”, an all-out effort to put a human into space. (The original proposed name was a prosaic “Project Astronaut”, but this was changed to make it sound more mythological.)
It was, for the time, an ambitious goal. The Army had already briefly put living test subjects such as fruit flies and rats above the atmosphere with short suborbital flights on modified V-2 rockets, but a human passenger presented designers with a long list of technical challenges that had to be met and questions whose answers were completely unknown.
This was complicated by the fact that, for reasons of economy and expediency, it was decided to make the Mercury design as simple and reliable as possible using existing off-the-shelf technology. The spaceship would be launched using already-existing nuclear missiles as boosters, and the pilot’s spacesuit would be a modified version of existing Air Force high-altitude pressure suits. The pilots themselves would be fully-qualified military test pilots, who were, it was assumed, best-suited for making rapid decisions under stress and who could best tolerate the physical and mental rigors of space flight. Seven Mercury astronauts—Alan Shepard, Gus Grissom, John Glenn, Scott Carpenter, Wally Schirra, Gordon Cooper and Deke Slayton—were presented at a press conference in April 1959.
Almost immediately the press and the public were captivated by the space program, and the “Mercury Seven” were adored as conquering heroes in the race against the Russians, even though they had not yet even seen a spaceship.
The task of designing the Mercury spacecraft fell to NASA engineer Maxime Faget and his team.
By the summer of 1959 NASA’s predecessor, the National Advisory Committee on Aeronautics (NACA), was already flying the experimental X-15 rocket plane, which was able to reach altitudes of 50 miles—almost to space. (Officially, the borderline to “space” is the Karman Line, set at 100 kilometers, or 62 miles.) Initial ideas for the Mercury vehicle envisioned improvements to the existing X-15 to enable it to reach higher altitudes. This raised a set of issues, however: the X-15 was designed to operate in atmosphere and was not capable of reaching orbit, it had no retro-rocket re-entry system or heat shield, and it had to be carried aloft by a heavy bomber and was too bulky for any of the existing missile launch vehicles. Faget therefore decided to design a smaller lighter spacecraft from scratch.
Much of what was then known about spaceflight came from testing with nuclear missiles. During their trajectory, nuclear warheads were carried aloft into space, and they had to re-enter the atmosphere at high velocity to reach their targets. To prevent them from burning up from friction with the air, warheads were carefully shaped into a blunt-ended cone which slowed it down and helped to dissipate the heat.
The planned sub-orbital space flights would also experience high temperatures, so to simplify the design Faget adopted a similar cone-shape for the Mercury craft and fitted the base of the spaceship with a heat sink made from beryllium, which would absorb most of the heat. For the higher-speed orbital flights, however, he replaced the beryllium with an ablative heat shield, made from layers of fiberglass laminated onto an aluminum honeycomb, which carried off more heat by boiling away. Since this would destroy the heat shield, it was intended that each Mercury craft would be used only once. The outside of the craft’s skin was made from small nickel-alloy plates.
Another design requirement revolved around the pilot. Most of NASA’s engineers viewed the Mercury’s occupant as more or less a mere passenger, not much different than the lab rats who had flown in the V-2 tests. Since the finished spaceship would have to be test-flown without a human before it could be “man-rated”, all of the systems would have to be automated and operated from the ground. Others, however, (especially the astronauts) argued that in the event of an emergency or hardware issue, the pilot had to be capable of assuming manual flight control when necessary. Further, for safety reasons, the vital systems had to be redundant so that the backup could take over if the primary system had a failure. All of this greatly complicated things and added significant weight to the spaceship, and cramming all of this into the tiny confines of the Mercury was a major headache for the designers.
They ended up with a blunt cone shape with an elongated nose, measuring a little under 11 feet long and 6 feet wide at the base and weighing almost 1.5 tons. Inside was a contoured couch (specially made to fit the individual astronaut) and panels containing dials, switches and warning lights. Three retro-rockets were strapped over the outside of the heat shield, which would be fired in orbit to slow the craft enough for re-entry. There was no on-board computer: any necessary mathematical calculations would be done on the ground.
The ship would be carried into space by a modified nuclear missile. Originally, plans called for three different boosters to be used. The first Mercury flights would use the Redstone intermediate-range missile, and since this did not have enough power to reach orbit these flights would follow an “up-and-down” ballistic trajectory. Sub-orbital flights would begin with chimp tests and conclude with human pilots. Next, a series of chimp flights would be made using the Jupiter rocket, in order to test the suitability of the Mercury’s systems for orbital flights. After that, orbital chimp tests would be made with the Atlas booster to man-rate it before a series of manned Mercury-Atlas missions. In the end, the Mercury-Jupiter series was cancelled as not being necessary.
The design team also needed a way to rescue the pilot if the booster failed to launch or if it exploded on the pad. Faget’s solution was to attach a small solid-fueled “launch escape rocket” which, in the event of an emergency, would pull the Mercury craft up and away from the rocket booster and carry it a safe distance away before landing it by parachute. The Launch Escape System and the associated Automatic Abort System were live-tested using a small booster rocket known as “Little Joe”.
A number of “boilerplate” Mercury models were produced, which lacked the internal systems, to be used in engineering tests. The flight-ready production models began to become available in the summer of 1960.
Today, all of the existing space-flown Mercury craft are on exhibit at various air and space museums. Of particular interest is the Mercury 15B, on display at the Smithsonian’s Udvar-Hazy Center in Washington DC. This craft was originally scheduled to fly on the three-day Mercury-Atlas 10 mission in the summer of 1963, with Alan Shepard as the pilot. Shepard had already named it “Freedom 7 II” and had undergone all the mission training. After Gordon Cooper’s Mercury-Atlas 9 flight in May 1963, however, it was decided that, after various issues had been encountered during the four manned Mercury-Atlas missions, there were too many questions about the durability of the spaceship for long-duration flights, and Shepard’s mission was canceled.
Because the Mercury-Atlas 10 mission was not flown, the spaceship is still in its pre-flight condition, with intact retro-rocket package, parachute, landing bag, and heat shield.
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