In Space 101: The Space Race and Wernher Von Braun, we’ve talked about how on May 5, 1961, Alan Shepard became the first American in space. But how did he get there? The answer – Project Mercury.

Project Mercury insignia
Project Mercury insignia (from NASA)

Project Mercury was the first American human space flight program, and it ran from 1958 to 1963. Its objectives were seemingly simple: orbit an astronaut around the Earth, determine how humans function in space, and then recover both the astronaut and the spacecraft successfully on Earth. From 1961 to 1963, Project Mercury achieved these objectives 6 times by sending 6 astronauts to space: Alan Shepard, Virgil (Gus) Grissom, John Glenn, Scott Carpenter, Walter Schirra, and Gordon Cooper. Each mission became increasingly longer, with Shepard’s lasting 4 minutes and Cooper’s lasting 34 hours. Cooper successfully orbited the Earth 22 times, or one full day in space.

Mercury capsule
Mercury capsule (from The Smithsonian Institute)

The Technology

The Mercury capsules were launched on top of Mercury-Redstone rockets for the first two manned missions, and Mercury-Atlas rockets for the final four. Thankfully, the US had acquired an incredibly valuable asset – the German rocket scientist Wernher von Braun. Without von Braun and the Mercury-Redstone rocket he developed, the Mercury missions would not have been possible in the early 1960s.

Mercury-Redstone rocket launching into space
Mercury-Redstone rocket (from NASA)

The Mercury capsules safely housed one astronaut in 100 cubic feet of habitable volume, and carried food, water, and oxygen for a one day trip around the Earth. Space flight has never been a comfortable endeavor for astronauts as its more important to minimize the weight of the spacecraft, but this small volume was sufficient for the mission requirements. The capsules were also equipped with the first launch abort system ever used, which was designed to safely carry the astronaut away from the launch vehicle in the event of an explosion or any other type of failure. This technology is still being used today in the new Artemis missions designed to send humans back to the Moon in the early 2020s, and as such was an incredibly important technological advancement in the field of human space flight.

Mercury capsule with astronaut depiction
Mercury capsule representation (from

NASA has always operated with the mindset of “if it isn’t broken, don’t fix it.” That is why the Mercury capsule looks extremely similar to the Apollo missions – using similar design concepts saves money and time, which was especially important during the Space Race. We are still using this capsule-type spacecraft today in the Artemis missions, though the design has improved significantly.

The Importance

Not only did the Mercury technology pave the way for the timely success of the Apollo missions later in that decade, but the ever-increasing time the astronauts spent in space during these missions allowed NASA to successfully study the effects on the human body during short-term space flight. Before the Mercury missions, we had only ever been able to guess what happened to the human body while flying in space. It was imperative that NASA understood how our bodies react in space short-term before sending humans to the Moon under JFK’s directive. Though common knowledge to us today, we learned from the Mercury studies that bodily functions including seeing, hearing, touching, tasting, smelling, eating, urinating, and respirating behaved as they do on Earth. Essentially, our bodies during short-term space flight behave very similarly to how they behave on Earth, and it was deemed acceptably safe to send humans on the longer trip to the Moon.

You can read more about the studies on the human body during the Mercury mission here.

Cool Facts

  • The first two flights were suborbital flights. Essentially this means they reached space, but not high enough to orbit the Earth, so they came right back to Earth. This was on purpose – simply to prove we had the capability of putting a man in space. Shepard’s flight flew to 116 miles above the surface of the Earth, and John Glenn’s flight in 1962 flew to 143 miles above the surface of the Earth, making him the first man to orbit Earth.
Graphic of Shepard’s and Glenn’s flight altitudes (from
  • Seven astronauts were originally selected for Project Mercury: the six listed above and Deke Slayton. Slayton unfortunately could not fly a Mercury mission due to a medical complication, but he was able to fly later in 1975. These 7 astronauts were called the Mercury Seven, and each astronaut got to name his capsule. After Shepard added a “7” to his capsule, calling it the Freedom 7 because it was the 7th Mercury capsule made, all subsequent astronauts added a 7 to theirs as well in tribute to the 7 astronauts selected for the program.
The Mercury Seven Astronauts (from NASA)
  • The name Mercury came from Roman mythology. The Roman God, Mercury, is commonly identified with the Greek Hermes, who is the “fleet-footed messenger of the Gods.”