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NASA Project Mercury: John Glenn and Friendship 7

This page is part of a series on America's first manned space program, Project Mercury. Links to all the articles in this series can be found at the NASA Project Mercury Overview.

Mercury astronaut John H. Glenn Jr., suited up before launch. Photo courtesy of NASA.

Mercury astronaut John H. Glenn Jr., suited up before launch. Photo courtesy of NASA.

At the start of 1962, America was far behind in the space race. The previous year, the Soviet Union had flown two manned orbital missions. Yuri Gagarin first orbited the earth in April, 1961, and in August cosmonaut Gherman Titov spent more than a day in space, orbiting the earth 17 times. By comparison, the United States had flown only two short, suborbital flights in 1961, for a combined total of just over 30 minutes of manned space flight experience.

America needed to launch something more than another suborbital flight, and soon. In the short-term, they needed to close the gap with the Soviets, but there was an equally important long-term goal. In 1961 American President Kennedy committed his nation to landing a man on the moon by the end of the decade. That goal would not seem even remotely realistic until an American astronaut orbited the earth.


To avoid confusion, NASA decided that all communication from the ground to an astronaut in space would go through one person, who would be known as the Capsule Communicator or CAPCOM. The Capsule Communicator would also be an astronaut, as it was felt that an astronaut could best convey critical information to another astronaut.

Friendship 7 is launched into orbit by a modified Atlas-D rocket.Photo courtesy of NASA.

Friendship 7 is launched into orbit by a modified Atlas-D rocket.Photo courtesy of NASA.

"Godspeed, John Glenn"

Originally scheduled for January 16, 1962, America's first manned orbital flight was repeatedly delayed by bad weather and technical issues. Finally, on February 20,1962, astronaut John H. Glenn, Jr. became the first American to orbit the earth. Liftoff was at 9:47 am EST, from Launch Complex 14 at Cape Canaveral, Florida. As the rocket ascended, fellow Mercury astronaut Scott Carpenter, acting as Capsule Communicator, or CAPCOM, conveyed the wishes of an entire nation with his send-off, "Godspeed, John Glenn."

Glenn named his spacecraft Friendship 7, but the mission was known officially as Mercury-Atlas 6, because it was the sixth Mercury launch to use a modified Atlas-D rocket. Prior to Glenn's flight there had been four Atlas launches with unmanned Mercury spacecraft, and a final test flight in which a chimpanzee named Enos orbited the earth twice.

To learn more about the different rockets used in Project Mercury, see: NASA Project Mercury - Launch Vehicles

Glenn orbited the earth three times, in an elliptical orbit with a maximum altitude (apogee) of 162 miles and minimum altitude (perigee) of 100 miles. Each orbit lasted 88 minutes and 29 seconds. The mission lasted 4 hours, 55 minutes, and 23 seconds, during which Glenn travelled a total of 75,679 miles.

Mission Control tracks the flight of Freedom 7. Photo courtesy of NASA.

Mission Control tracks the flight of Freedom 7. Photo courtesy of NASA.

Communications and Tracking

To track and communicate with Friendship 7 as it circled the globe, the Mercury Tracking Network was established. It was made up of sixteen land-based stations and two US Air Force vessels, one in the Atlantic Ocean and one in the Indian Ocean. These stations had equipment for tracking the spacecraft, receiving telemetry data, and establishing voice communications with the astronaut. In addition, they had the capability to assume control of the spacecraft from the ground, if necessary.

The Effects of Weightlessness

Because this was NASA's first long-duration space flight, there were still many unknowns regarding the effects of weightlessness on the human body. Would it be possible to swallow food? Would fluids in the inner ear float freely, causing motion sickness and nausea? Would eyeballs lose their shape, distorting vision? After an extended period of weightlessness, would an astronaut be able to withstand the increased g-forces of reentry? Glenn's mission would attempt to answer these questions.

Glenn had no difficulty swallowing foods squeezed from tubes, or chewing and swallowing malted milk tablets. He felt no nausea or motion sickness, even when deliberately moving and turning his head in an attempt to induce these sensations. Every 30 minutes, he read from a small eye chart placed on his instrument panel, and experienced no distortion in vision throughout his flight. He found weightlessness to be comfortable, and had no difficulty with g-forces at the end of the flight.

Fireflies In Space?

As Friendship 7 encountered sunrise for the first time, Glenn saw thousands of luminous particles, which he described as looking like fireflies, floating outside the spacecraft. They did not appear to Glenn to be coming from the spacecraft, but rather seemed to be streaming slowly past the spacecraft from ahead. The source of these particles would be discovered by Scott Carpenter on the next Mercury flight, but remained a mystery during Glenn's mission. Before his flight ended, however, Glenn would be confronted with a much larger issue than fireflies.


The retropack was a collection of small rockets, called retrorockets, that would fire at the end of a mission to slow the spacecraft, allowing it to re-enter the atmosphere. The pack, which would normally be jettisoned after firing, was attached with straps that stretched across the heatshield.

To learn more about the Mercury spacecraft, see: NASA Project Mercury - Spacecraft

Telemetry Indicates A Problem

As Glenn began his second orbit, telemetry data from Friendship 7 suggested a problem with the spacecraft. A reading from the sensor monitoring the spacecraft's heat shield and landing impact bag indicated that the impact bag had deployed. This could only happen if the heat shield had come loose. If this were the case, Glenn might be incinerated during reentry.

Mission Control felt that the reading was most likely caused by a faulty sensor on the spacecraft, and that Glenn's heatshield was fine, but they couldn't be sure. After discussing the issue, they advised Glenn not to jettison his retropack before reentry. If the heatshield were loose, keeping the pack attached might hold it in place.

This strategy had risks, however. As the retropack itself burned up, pieces could fly off and damage the spacecraft. The heat of reentry might also cause any fuel remaining in the rockets to explode. As with all space flights, there would be a temporary radio blackout during reentry, caused by ionization of the atmosphere. Mission Control would not know if Glenn had survived until this period of radio blackout was over.

A National Hero

The Mercury astronauts had all been national heroes since they were introduced to the public in 1959, but this mission catapulted John Glenn to even greater glory. He retired from NASA in 1964 and found great success in business and politics. From 1974 to 1999, Glenn served as United States Senator from the state of Ohio.

To learn more about the original Mercury astronauts, see: NASA Project Mercury - The Mercury 7 Astronauts

John Glenn meets with President Kennedy following his mission. Photo courtesy of NASA.

John Glenn meets with President Kennedy following his mission. Photo courtesy of NASA.

New Recovery Procedures

The telemetry data had been wrong. Glenn's heatshield was firmly attached, and Friendship 7 safely splashed down in the Atlantic Ocean, 800 miles southeast of Bermuda.

Following the loss of Liberty Bell 7 on the previous Mercury flight, new procedures for spacecraft recovery were devised. First, frogmen placed a flotation collar around the spacecraft, to help keep it afloat if it filled with water. Then, instead of using a helicopter to lift the capsule from the water and carry it to a nearby vessel, the recovery vessel would come alongside the spacecraft and lift it by crane to the ship's deck. All future Mercury, Gemini and Apollo capsules would be recovered this way.

Back In The Race

With the success of John Glenn's mission, Project Mercury met its original goals of putting a man in orbit and safely returning him to earth, and observing the effects of extended weightlessness on humans.

The United States still lagged behind the Soviet Union, who had larger spacecraft, more powerful rockets, and had flown longer missions, but by successfully putting a man in orbit, America had put itself back in the space race.


In addition to the sources listed on the Project Mercury - Overview page, information for this article came from the following original source documents:

  • NASA, Mercury-Atlas 6 Press Kit, NASA, 1962
  • Manned Spacecraft Center, Results of the First U.S. Manned Orbital Space Flight - February 20, 1962, NASA, 1962

Video: Mercury-Atlas 6


person on March 29, 2012:

heat sheild

bailey on March 26, 2012:

what was the problems