The History and Legacy of Project Mercury

Mercury 7 monument
The monument to Project Mercury, which honors the original 7 Mercury astronauts. It's located at Launch Complex 14 at Cape Canaveral/Kennedy Space Center. NASA

For people who were living in the 1950s and 1960s, the Space Race was an exciting time when people were venturing out from Earth's surface and heading to the Moon, and hopefully beyond. It officially began when the Soviet Union beat the U.S. into space with the Sputnik mission in 1957 and with the first man into orbit in 1961. The U.S. scrambled to catch up, and the first human crews went to space as part of the Mercury program.

The program goals were fairly simple, although the missions were quite challenging. Mission aims were to orbit a person in a spacecraft around Earth, investigate a human's ability to function in space, and to recover both astronaut and spacecraft safely. It was a formidable challenge and it affected the scientific, technological, and educational establishments of both the U.S. and the Soviets.

The Origins of Space Travel and the Mercury Program

While the Space Race got started in 1957, it had roots much earlier in history. No one is exactly sure when humans first dreamed of space travel. Perhaps it began when Johannes Kepler wrote and published his book Somnium. However, it wasn't until the middle of the 20th century that technology developed to the point where people could actually transform ideas about flight and rockets into hardware to achieve space flight. Initiated in 1958, completed in 1963, Project Mercury became the United States's first man-in-space program.

Creating the Mercury Missions

After setting goals for the project, the newly formed NASA adopted guidelines for the technology that would be used in the space launch systems and crew capsules. The agency mandated that (wherever it was practical), existing technology and off-the-shelf equipment should be used.

Engineers were required to take the simplest and most reliable approaches to system design. This meant that existing rockets would be used to take the capsules into orbit. Those rockets were based on captured designs from the Germans, who had designed and deployed them during World War II. 

Finally, the agency set up a progressive and logical test program for the missions. The spacecraft had to be built tough enough to withstand a great deal of wear and tear during launch, flight, and return. It also had to have a reliable launch-escape system to separate the spacecraft and its crew from the launch vehicle in case of impending failure. This meant that the pilot had to have manual control of the craft, the spacecraft had to have a retrorocket system capable of reliably providing the necessary impulse to bring the spacecraft out of orbit, and its design would allow it to use drag braking for re-entry. The spacecraft also had to be able to withstand a water landing because, unlike the Russians, NASA planned to splash its capsules down in the ocean. 

Although most of this was accomplished with off-the-shelf equipment or through the direct application of existing technology, two new technologies had to be developed.

Those were an automatic blood-pressure measuring system for use in flight, and instruments to sense the partial pressures of oxygen and carbon dioxide in the oxygen atmosphere of the cabin and space suits.

Mercury's Astronauts

The Mercury program leaders decided that the military services would provide the pilots for this new endeavor. After screening more than 500 service records of test and fighter pilots in early 1959, 110 men were found that met the minimum standards. By the middle of April America's first seven astronauts were selected, and they became known as the Mercury 7. They were Scott Carpenter, L. Gordon Cooper, John H. Glenn Jr., Virgil I. "Gus" Grissom, Walter H. "Wally" Schirra Jr., Alan B. Shepard Jr., and Donald K. "Deke" Slayton

The Mercury Missions

The Mercury Project consisted of several unmanned test missions as well as a number of missions taking pilots into space.

The first one to fly was Freedom 7, carrying Alan B. Shepard into a suborbital flight,on May 5, 1961. He was followed by Virgil Grissom, who piloted the Liberty Bell 7 into a suborbital flight on July 21, 1961. The next Mercury mission flew on February 20, 1962, carrying John Glenn into a three-orbit flight aboard Friendship 7.  Following Glenn's historic flight, astronaut Scott Carpenter rode Aurora 7 into orbit on May 24, 1962, followed by Wally Schirra aboard Sigma 7 on October 3, 1962. Schirra's mission lasted six orbits. The final Mercury mission took Gordon Cooper into a 22-orbit track around Earth aboard Faith 7 on May 15-16, 1963.

At the end of the Mercury era, with its technology proven, NASA prepared to move forward with the Gemini missions. These were planned as preparation for the Apollo missions to the Moon. The astronauts and ground teams for the Mercury missions proved that people could fly safely to space and return, and laid the groundwork for much of the technology and mission practices followed by NASA to this day. 

Edited and updated by Carolyn Collins Petersen.