Mercury

Overview

Project Mercury came into being on October 7, 1958, only a year and three days after the Soviet Union’s Sputnik I satellite opened the Space Age. The goal of sending people into orbit and back had been discussed for many years before that, but with the initiation of the Mercury project, theory became engineering reality.

Mercury engineers had to devise a vehicle that would protect a human being from the temperature extremes, vacuum and newly discovered radiation of space. Added to these demands was the need to keep an astronaut cool during the burning, high-speed reentry through the atmosphere. The vehicle that best fit these requirements was a wingless “capsule” designed for a ballistic reentry, with an ablative heat shield that burned off as Mercury returned to Earth.

Mercury capsules rode into space on two different kinds of booster. The first suborbital flights were launched on Redstone rockets designed by Wernher von Braun’s team in Huntsville, Alabama. For orbital flights, Mercury was placed on top of an Atlas-D, a modified ballistic missile whose steel skin was so thin (to save weight) it would have collapsed like a bag if not pressurized from within.

The first Americans to venture into space were drawn from a group of 110 military pilots chosen for their flight test experience and because they met certain physical requirements. Seven of those 110 became astronauts in April 1959. Six of the seven flew Mercury missions (Deke Slayton was removed from flight status due to a heart condition). Beginning with Alan Shepard’s Freedom 7 flight, the astronauts named their own spacecraft, and all added 7 to the name to acknowledge the teamwork of their fellow astronauts.

With only 12,133 cubic meters of volume, the Mercury capsule was barely big enough to include its pilot. Inside were 120 controls, 55 electrical switches, 30 fuses and 35 mechanical levers. Before Shepard’s flight, surrogate “passengers” tested the integrity of the spacecraft design: two rhesus monkeys, Ham the chimpanzee, and an electronic “crewman simulator” mannequin that could breathe in and out to test the cabin environment. Finally, in May 1961, Shepard became the first American in space. Nine months later, John Glenn became the first American to orbit the Earth.

The six Mercury flights (which totaled two days and six hours in space) taught the pioneers of space flight several important lessons. They learned not only that humans could function in space, but that they were critical to a mission’s success. Ground engineers learned the difficulty of launch preparations, and found that a worldwide communications network was essential for manned space flight.

By the time of the last Mercury flight in May 1963, the focus of the U.S. space program had already shifted. President John F. Kennedy had announced the goal of reaching the Moon only three weeks after Shepard’s relatively simple 15-minute suborbital flight, and by 1963, only 500 of the 2,500 people working at NASA’s Manned Spacecraft Center were still working on Mercury-the remainder were already busy on Gemini and Apollo.

But Mercury had taken the critical first step, and had given reassuring answers to a number of fundamental questions:

• Could humans survive in space?
• Could a spacecraft be designed to launch them into orbit?
• Could they return safely to Earth?

At the moment John Glenn’s Friendship 7 capsule was placed into its orbital trajectory, fulfilling the primary goal of Project Mercury, one member of the launch team on the ground made a notation in his log: “We are through the gates."

Mercury Statistics

Bibliography

NASA Sources

• Grimwood, James M. Project Mercury: A Chronology. (NASA SP-4001, 1963).
• Hansen, James R. Spaceflight Revolution: NASA Langley Research Center from Sputnik to Apollo. (NASA SP-4308, 1995).
• Link, Mae Mills. Space Medicine in Project Mercury. (NASA SP-4003, 1965).
• Pitts, John A. The Human Factor: Biomedicine in the Manned Space Program to 1980. (NASA SP-4213, 1985).
• Swenson, Loyd S., Jr., Grimwood, James M., and Alexander, Charles C. This New Ocean: A History of Project Mercury. (NASA SP-4201, 1966).
• Results of the Second U.S. Manned Orbital Space Flight. NASA SP-6, 1962.
• Results of the Third U.S. Manned Orbital Space Flight. NASA SP-12, 1962.
• Mercury Project Summary Including Results of the Fourth Manned Orbital Flight. NASA SP-45, 1963.

Non-NASA Sources

• Catchpole, John. Project Mercury: NASA’s First Manned Space Programme. Springer-Praxis, 2001.
• Wolfe, Tom. The Right Stuff. Farrar, Straus & Giroux, 1979.
• Mercury Astronauts. We Seven. Simon and Schuster, 1962.

Mercury Missions

Mercury-Redstone 3 (Freedom 7)

5 May 1961

Crew: Alan B. Shepard, Jr.

Alan Shepard’s suborbital flight lasted only 15 minutes, but it proved that an astronaut could survive and work comfortably in space and demonstrated to the 45 million Americans watching onTV that the United States was now in the spaceflight business. Freedom 7 was a ballistic “cannon shot”—Shepard reached no higher than 187.45 kilometers (116.5 statute miles) and traveled only 486.022 kilometers (302 statute miles) downrange from Cape Canaveral.During his short time in space, he maneuvered his spacecraft using hand controllers that pitched, yawed, and rolled the tiny Mercury capsule with small thrusters. He found the ride smoother than expected and reported no discomfort during 5 minutes of weightlessness. Although this first Mercury capsule lacked a window, Shepard was able to look down at the Atlantic coastline through a periscope. His view,though, was in black and white—the astronaut had inadvertently left a gray filter in place while waiting on the pad for liftoff.

Mercury-Redstone 4 (Liberty Bell 7)

21 July 1961

Crew: Virgil I. “Gus” Grissom

Gus Grissom’s suborbital mission was essentially a repeat of Shepard’s, again using the Redstone launcher instead of the more powerful Atlas. Grissom’s Mercury capsule had a few minor improvements, including new, easier-to-use hand controllers; a window; and an explosive side hatch, which the astronauts had requested for easier escape in case of an emergency. Since Shepard’s flight had been overly busy, Grissom’s duties were deliberately reduced, and he spent more time observing Earth. The only significant failure came at the end of the 15-minute flight, after Liberty Bell 7 had parachuted into the Atlantic Ocean near the Bahamas. While Grissom waited inside the floating capsule to be picked up by helicopter rescue teams, the side hatch opened, filling the tiny spacecraft with seawater. Liberty Bell 7 sank, but a wet Grissom was safely recovered and the Mercury program was able to move on to orbital flights.

Mercury-Atlas 6 (Friendship 7)

20 February 1962

Crew: John H. Glenn, Jr.

John Glenn’s orbital flight—an American first—lasted 4 hours and 55 minutes, during which he circled Earth three times and observed everything from a dust storm in Africa to Australian cities from an altitude of 260.71 kilometers (162 statute miles). Glenn was the first American to see a sunrise and sunset from space and was the first photographer in orbit, having taken along a 35-millimeter Minolta camera purchased from a Cocoa Beach, Florida, drugstore. The most nerve-wracking moments of the flight came before and during reentry, when a signal received on the ground (erroneously, as it turned out) indicated that the capsule’s heatshield had come loose. At one point, Glenn thought his shield was burning up and breaking away. He ran out of fuel trying to stop the capsule’s bucking motion as it descended through the atmosphere, but it splashed down safely, 64.37 kilometers (40 statute miles) short of his target (preflight calculations of the spacecraft’s weight had not considered the loss of on-board “consumables”). Glenn returned to Earth a national hero, having achieved Project Mercury’s primary goal of sending an astronaut into orbit.

Mercury-Atlas 9 (Faith 7)

15–16 May 1963

Crew: L. Gordon Cooper, Jr.

If Schirra’s mission was an endurance test,the final Mercury flight was a marathon. Gordon Cooper circled Earth 22.5 times and released the first satellite from a spacecraft, a 152.4-millimeter (6-inch) sphere with a beacon for testing the astronaut’s ability to track objects visually in space. Although a balloon for measuring atmospheric drag failed to deploy properly, Cooper finally completed another Mercury experiment when he was able to spot a powerful, 44,000-watt xenon lamp shining up from the ground. (He also claimed to be able to see individual houses from orbit and even to see smoke from chimneys in the Tibetan highands.) During his 34 hours in space, Cooper slept, spoke a prayer into his tape recorder, and took the best photographs of the Mercury program, including pictures of Earth’s limb and infrared weather photographs. His mission was deemed a “great success.” It was so successful, in fact, that it allowed Mercury officials to cancel a planned seventh flight and move on to the two-man Gemini program.