How Project Mercury Worked

In 1958, the early days of Project Mercury, it was not clear what type of person could be an astronaut. Several types were considered, including stunt men, circus performers, swimmers and race-car drivers. President Eisenhower decided that the astronauts should be military pilots, particularly test pilots. Furthermore, they should be college-educated, family-oriented, of average height and build, in excellent health and dedicated to flying advanced aircraft.

NASA officials began screening the service records of military flyers. They narrowed the field of 508 down to 110 pilots from the Marines, Navy and Air Force (no Army pilots were invited because none had graduated from a test-pilot school). Of these 110 men, 69 reported to Washington, D.C. in February 1959 for the screening tests, which included interviews (technical and psychological), written tests and medical examinations. Of these 69 men, 32 were selected and agreed to undergo further testing in Ohio and New Mexico. These tests included extensive medical and psychological evaluations, as well as stress tests in conditions such as high G-forces, vibration and isolation.

On April 9, 1959, at a press conference in Washington, D.C., NASA introduced the Project Mercury astronauts:

Most of the Mercury astronauts were veterans of World War II and/or the Korean War. They had extensive flight experience and were in excellent health.

After selection, the crew underwent several years of training in the Mercury-spacecraft systems, as well as flight training, continuous medical evaluations and survival training in many environments (such as desert, jungle and ocean). They worked hard, played hard and endured many hours of separation from their families, each crew member vying to become the first American in outer space.

The astronauts became celebrities as the press and public focused on them. They made public appearances for NASA to promote the fledgling space program, and they used the public attention to increase their influence in the program.

In addition to training and public relations, they consulted on the development of the Mercury spacecraft. Despite objections from the engineers who designed the spacecraft, the astronauts insisted on having a window, manual re-entry thruster controls and an escape hatch with explosive bolts -- they wanted the ability to actively fly the spacecraft and, if necessary, escape from it. They were pilots, and the thought of merely riding in a totally automated spacecraft went against their nature.

After years of preparation, the initial flight assignments were made: Shepard would be the first American in space, followed by Grissom and then Glenn.

The Mercury spacecraft was designed to carry one man alone into outer space and return him safely. It was cone-shaped -- 6.8 feet (2 m) long, 6.2 feet (1.9 m) in diameter at the base -- with a small cylinder on top. The spacecraft weighed between 2,300 and 3,000 pounds (1,043 to 1,360 kg), depending on the mission, and sat on top of a boosterrocket. Atop the spacecraft, there was anemergency escape towerthat could lift the capsule off the booster, raising it to an altitude where the parachutes could open and return the capsule and astronaut to the ground at a safe distance from the launch pad. On the blunt end of the spacecraft there was aheat shield, which protected the capsule from the heat of re-entry, and aretro-pack, which were small rocket thrusters that slowed the spacecraft down for re-entry.

Like any spacecraft, Mercury had to provide the following systems:

The Mercury spacecraft had two boosters, the Redstone and Atlas rockets. Both rockets were ballistic missiles that were modified to carry spacecraft payloads instead of warheads.

NASA encountered several failures of the early Redstone and Atlas launches, with the launch vehicles exploding at various stages. When the problems were fixed, unmanned and animal launch tests were conducted. The Redstone was used on the first two manned suborbital flights, but it was not as powerful as the Atlas. The Atlas was used to place men into orbit on the remaining Mercury flights.

The goals of the Mercury space program were to orbit a manned spacecraft around the Earth, investigate man's ability to function in space and recover the man and spacecraft safely. By 1961, the race to accomplish these goals was in high gear because of the Cold War. The astronauts had been selected and trained, and the spacecraft built and tested. NASA officials, particularly the lead rocket scientistWernher Von Braun, insisted that the booster/spacecraft be tested by flying chimpanzees into outer space. Two such flights occurred before it was certified as ready for a manned mission. While these tests were being conducted, the Soviets launched CosmonautYuri Gagarininto Earth orbit. In April 1961, Gagarin became the first man to reach outer space. NASA was criticized by the press and public, who felt that the United States could have put a man in outer space before the Soviets. The Soviet achievement placed the United States far behind in the space race. NASA relied on astronaut Alan Shepard to put America back in the game.

On May 5, 1961, Alan Shepard climbed aboard his Mercury spacecraft, called Freedom 7. His mission was to fly into outer space and return safely in a sub-orbital flight that would last about 15 minutes. There were numerous delays in the countdown, and Shepard was on the pad for hours. Finally, at 9:43 AM, Alan Shepard was launched into outer space. Shepard reached an altitude of 116 miles (187 km) and landed 303 miles (488 km) down-range from Cape Canaveral, where he was recovered by the aircraft carrier Lake Champlain. He reached a peak velocity of 5,134 miles per hour (8,260 kph) and experienced a force as high as 11 Gs (11 times the acceleration due to gravity) upon re-entry. The flight lasted 15 minutes and 28 seconds. Unlike Gagarin, Shepard was able to maneuver the craft during flight. Shepard's historic flight launched the U.S. space program, ultimately, to the moon.

Alan Shepard was later grounded due to an inner-ear disorder. He worked in the Astronaut Office for many years before having surgery to correct his ear problem. He moved on to command the Apollo-14 mission and walk on the moon. He was the only Mercury astronaut to go to the moon, as well as the only man (to this day) to golf on the moon. Alan Shepard died in 1998.

Shepard's groundbreaking flight was followed by another sub-orbital flight by Gus Grissom and four orbital flights by Glenn, Carpenter, Schirra and Cooper (to learn about these subsequent Mercury missions, seeHow Project Mercury Missions Worked). The men and missions of Project Mercury established that America could place a person in orbit, that he could survive in space and that he could return successfully. Project Mercury established a foothold for America in the space race and paved the way for Projects Gemini and Apollo. As of 2001, Mercury astronauts Glenn, Carpenter, Schirra, and Cooper are still alive, although retired from space endeavors. The pioneering contributions of these men to aviation and space exploration will always be remembered.