Project Mercury

FAS Astronomers Blog, Volume 30, Number 2.

Sixty years ago this month (February 20, 1962), Astronaut John Glenn became the first American to orbit the Earth. He did so as part of NASA’s Project Mercury. This is the story.

On October 4, 1957, a small round ball called Sputnik was launched into orbit by the Soviet Union. The impact of Sputnik, the first artificial satellite, resonated around the world. The United States tried to follow in December 1957 with Vanguard TV-3. It failed and became known by various names including “Flopnik” and my favorite “Stayputnik.” In late January 1958, the United States successfully sent Explorer 1 into orbit and the space race began.

After successfully launching its first few satellites, the United States decided it needed to move to the next stage and place humans (men) in space. Therefore, in 1958, along came Project Mercury. Astronauts would ride a small capsule (about the size of a small closet), be launched from the top of an ICBM ballistic missile, and, for the first time, fly above the Earth’s atmosphere.

After some deliberation it was decided that military test pilots would become the first astronauts. The candidates had to be shorter than 5’ 11”, less than 40 years of age, and have a college degree. Initially 110 men met the criteria. After a rigorous selection process, the number was reduced to seven and the first astronauts were introduced to the nation at a press conference on April 9, 1959. They were Scott Carpenter, Gordon Cooper, John Glenn, Gus Grissom, Wally Schirra, Deke Slayton, and Alan Shepard. The U.S. was ready for the new frontier.

Mercury Astronauts
Image Credit: NASA

Getting the Mercury capsule into space wasn’t an easy task. Initially, it would be flung into space on a Redstone booster. The Redstone didn’t have enough thrust to place the spacecraft into orbit, so later flights would use an Atlas rocket. The Redstone and Atlas were both less than 100 feet high (compared to the Saturn V at over 360 feet). The Redstone produced a thrust of 78,000 lbs., and the Atlas around 400,000 lbs. (compared with the Saturn V’s overall thrust in excess of 8,500,000 lbs.). The various Mercury flights were designated MR for Mercury Redstone and MA for Mercury Atlas.

Redstone
Image Credit: NASA
Atlas
Image Credit: NASA

The first few unmanned test missions were launched from Wallops Island off the coast of Virginia using a booster called Little Joe.

  • Little Joe 1 was scheduled to launch on August 21, 1959. As the countdown proceeded, people were slowly moving to safe locations for the launch. Then around a ½ hour before launch, the escape tower ignited pulling the capsule away and sending spectators scrambling. Although, the escape tower worked as planned, it was supposed to fire after the spacecraft launched, not before.
  • Little Joe 1A was a little more successful. The spacecraft took off and was recovered, although they were unable to test the escape tower.
  • Little Joe 2 lifted off on December 2, 1959 and flew to a height of 53 miles and a distance downrange of 194 miles. The passenger, rhesus monkey Sam, was weightless for over 3 minutes.
  • Little Joe 1B followed a few weeks later on January 21, 1960 reaching a height of 9 miles. The passenger was another rhesus monkey, Miss Sam.
  • Little Joe 5, 5B and 6 flew with varying degrees of success.

There was also a Big Joe test of the Mercury Capsule heat shield on September 9, 1959. The capsule took off on an Atlas rocket that failed to push it to the desired height. However, the heat shield worked, and the test was considered a success.

The next flights involved a Mercury capsule with a Redstone booster.

  • MR-1 was scheduled to take off on November 21, 1960. The Redstone engine ignited. The vehicle rose a few inches and settled back down on the pad. The escape tower fired and landed 400 yards away, which is what it’s supposed to do. However, it did so without taking the spacecraft with it. With the escape tower gone, the capsule’s drogue, main, and backup parachutes all deployed, and the green die marker was released. All this is occurred while the capsule was still attached to the launch vehicle and sitting on the pad.
  • MR-1A was a little more successful. It lifted off on December 19, 1960 and reached a height of 130 miles and was weightless for over 5 minutes.
  • MR-2 was next with Ham, a chimpanzee as the “pilot”. The flight had a few problems. It flew higher and landed farther down range than expected. But the pilot was in satisfactory condition after landing.
  • MR-BD (“Booster Development”) flew on March 24, 1961 and reached an altitude of 113 miles.

The last test flight caused some controversy. Some people, including the astronauts, were ready to go, but Wernher Von Braun, the head of the Marshall Space Flight Center, felt that one more test flight (MR-MD) was needed. This delay proved to be costly. Before the U.S. could get a man into space, something happened! On April 12, 1961, folks in the western hemisphere woke up to disconcerting news. The Soviet Union had done it again. They put the first man into space. Vostok 1, with Cosmonaut Yuri Gagarin, orbited the Earth and returned safely.

Three weeks later, on May 5, 1961, Freedom 7 took off with astronaut Alan Shepard. Unlike Gagarin, who orbited the Earth, Shepard flew a short suborbital flight. He reached an altitude of 116.5 miles and landed 303 miles down range from Cape Canaveral. The flight lasted only 15 minutes and 28 seconds, but the U.S. had placed a man into space.

The United States was still not ready for an orbital flight, so another suborbital flight was next. Gus Grissom and Liberty Bell 7 lifted off on July 21, 1961. The flight went smoothly until after the landing. Grissom disconnected his oxygen hose and removed his helmet while waiting for the rescue crew to pick him up. He also removed the pin from the hatch cover detonator. He then heard a dull thud. The hatch had blown, and water was rushing into the capsule. Grissom pulled himself through the hatch and into the ocean. He was rescued, but Liberty Bell 7 sank to the bottom of the ocean.

Getting into orbit was the true goal of project Mercury. This required the Atlas booster. From mid-1960 to the fall of 1961, NASA launched several un-crewed MA missions.

  • Two (MA-1 and MA-3) exploded shortly after takeoff.
  • One (MA-2) was only a suborbital flight.
  • MA-4 finally made it to orbit in September 1961. NASA decided one more test would be needed.
  • MA-5 launched on November 29, 1961. It reached orbit and an altitude of 147 miles. After two orbits, the spacecraft reentered the atmosphere and splashed down 30 miles from the recover ship. The “pilot” was Enos, the first chimpanzee to orbit the Earth.

Before the United States could get an astronaut into orbit, the Soviets put cosmonaut Gherman Titov into orbit for an entire day on August 6, 1961.

After several delays, Friendship 7 (MA-6) made it into orbit on February 20, 1962, with John Glenn on board. The flight was going well, until Mercury Control received a warning indicator that the spacecraft’s heat shield was loose. The decision was made to keep the retrorocket package attached to the spacecraft during reentry to hold the heat shield in place. As a result, fiery chunks of the retro package flew by his window as Glenn was re-entering the atmosphere. Friendship 7 landed safely, and it was later determined that there was a faulty switch and nothing wrong with heat shield itself. Glenn also noticed mysterious “fireflies” outside his window that he was unable to identify. Although Alan Shepard flew first, it was Glenn who quickly became a national hero, and he is the one the public most remembers.

John Glenn
Credit: NASA

A second orbital flight (MA-7) was scheduled for May 1962. The pilot would be Deke Slayton in Delta 7. Slayton had been diagnosed with an irregular heartbeat back in August 1959. However, it was decided to keep him on active status and to eventually assign him a flight. As his flight was approaching, Slayton’s condition was reevaluated, and over the objections of several folks in NASA, Slayton was grounded on March 15, 1962. Slayton was soon promoted to head the astronaut office and quickly took over the duties of making crew assignments for future flights, including the Gemini and Apollo missions.

Wally Schirra was the backup for MA-7. However, NASA felt that Scott Carpenter was more prepared because of his role as Glenn’s backup, so Carpenter was chosen for MA-7. Aurora 7 took off on May 24, 1962. During his three orbits Carpenter had several difficulties. He used an excessive amount of fuel, he got behind on his retro rocket check list, and he had trouble holding the capsule at the correct angle for reentry. Aurora 7 ended up well downrange from his designated landing site. It took a few hours for the rescue teams to find the astronaut and get him safely on board an aircraft carrier. Despite the problems, Carpenter did discover that Glenn’s fireflies were just frost flaking off the side of the capsule.

Sigma 7 (MA-8) was next with Wally Schirra. Schirra was the practical joker of the Mercury 7 astronauts, but when it came to the mission, he was an extremely focused pilot. After Aurora 7, he was determined to make sure the checklist was completed, and fuel would be conserved. Sigma 7 took off on October 3, 1962, beginning a six-orbit flight, which would double the time in space for a U.S. astronaut. As he approached the end of his last orbit, he had plenty of fuel remaining. After the retro rockets fired, the fuel level stood at around 50%. Schirra landed in the Pacific Ocean and waited until the spacecraft was on the deck of an aircraft carrier to exit. He triggered the explosive bolts to blow the hatch. In doing so, he demonstrated that blowing the hatch took a significant effort and he bruised his hand casting doubt on the theory that Gus Grissom had blown the hatch on his flight.

With the success of Sigma 7, it was decided to push the last mercury flight to a full day. The last of the active original 7 astronauts was Gordon Cooper and he would fly in Faith 7 (MA-9). Cooper was known as a bit of a “hot dog.” Two days before his launch, he flew a NASA jet at a high rate of speed near the second-floor window of the NASA administration building interrupting a meeting between operations director Walt Williams and flight director Chris Kraft. After some discussion with Deke Slayton and threats to remove Cooper from the flight, it was decided that he would still fly the mission.

Faith 7 lifted off on May 15, 1963, and everything went well until the end of the flight. Around the nineteenth orbit, Cooper received a false indicator that the capsule was decelerating. Then there was a loss of almost all electrical power. This took out the attitude control system, the gyroscopes, and the clock. The carbon dioxide readings were also getting a bit high. On the 22nd orbit, despite all the problems, Cooper performed a manual reentry by lining up the spacecraft with the horizon and manually firing the retro rockets. He landed on target in the Pacific Ocean.

A three-day Mercury orbital flight had been planned with Alan Shepard on board. The Mercury capsule was built, and Shepard named it Freedom 7-II. However, it was eventually decided to forgo another Mercury flight and move on to project Gemini.

The Mercury program ended up being very successful and led the way for the Gemini program with which NASA developed the techniques required to get to the Moon.

Despite the success, the Soviet Union continued to lead the space race with several multi-day flights. Andriyan Nikolayev (Vostok 3) and Pavel Popovich (Vostok 4) flew simultaneous missions in August 1962. Valery Bykovsky (Vostok 5) and Valentina Tereshkova (Vostok 6), the first woman to fly in space, followed with similar missions in June 1963.

Portions of this article overlap with and were adapted from an earlier article, First Humans in Space. Much of this history of Project Mercury can be found in This New Ocean: A History of Project Mercury.

Selected Sources and Further Reading

“Project Mercury.” NASA. (Accessed January 30, 2022). https://www.nasa.gov/mission_pages/mercury/index.html

“What Was Project Mercury?” NASA. December 16, 2008. Updated August 7, 2017. https://www.nasa.gov/audience/forstudents/5-8/features/nasa-knows/what-was-project-mercury-58.html

Jim Dumoulin. “Project Mercury.” NASA/KSC. Mercury Archives. Updated August 25, 2000. https://science.ksc.nasa.gov/history/mercury/mercury.html

“Mercury Crewed Flights Summary.” November 30, 2006. Updated November 2, 2018. (Accessed January 30, 2022). https://www.nasa.gov/mission_pages/mercury/missions/manned_flights.html

Loyd S. Swenson Jr., James M. Grimwood, and Charles C. Alexander. This New Ocean: A History of Project Mercury. NASA Special Publication-4201 in the NASA History Series. 1989. https://history.nasa.gov/SP-4201/toc.htm & https://history.nasa.gov/SP-4201.pdf

James M. Grimwood. Project Mercury A Chronology. NASA SP-4001. https://history.nasa.gov/SP-4001/cover.htm

“Project Mercury Overview – Astronaut Selection.” NASA, Project Mercury. November 30, 2006. https://www.nasa.gov/mission_pages/mercury/missions/astronaut.html

“Mercury: 1958-1963.” NASA/JSC. https://historycollection.jsc.nasa.gov/JSCHistoryPortal/history/mercury.htm

Christopher Kraft with James L. Schefter. Flight, My Life in Mission Control. Penguin Books. New York. 2001. https://www.goodreads.com/book/show/141498.Flight

Alan Shepard and Deke Slayton with Jay Barbree and Howard Benedict. Moon Shot, The Inside Story of America’s Race to the Moon. Turner Publishing, Inc. Atlanta. 1994. https://www.goodreads.com/book/show/1142063.Moon_Shot

Tom Wolf. The Right Stuff. Farrar, Straus & Giroux. September 1979. https://us.macmillan.com/books/9780312427566/therightstuff

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