REPRINTED FROM SPACENEWS
Originally posted: 19 February 2008
WASHINGTON — By the end of 1961 the space race between the United States and the Soviet Union had heated up.
In August of that year, the Soviets sent up their second orbital flight, with Cosmonaut Gherman Titov aboard, while the United States had completed just two suborbital flights. Feeling the pressure, NASA decided to advance its flight schedule by dropping a third planned suborbital flight and instead accelerating its upcoming orbital mission.
That was good news for John Glenn, who had been disappointed to be picked to be the third U.S. astronaut in space behind Alan Shepard and Virgil “Gus” Grissom. Glenn may not have been the first U.S. astronaut in space, but the affable pilot became the first U.S. astronaut to orbit the Earth after his Mercury capsule, dubbed Friendship 7, launched Feb. 20, 1962, from Cape Canaveral, Fla., aboard an Atlas rocket.
Glenn was a Marine fighter pilot who flew 59 combat missions during World War II and 63 combat missions during the Korean War. He also had served as a test pilot and as an advanced flight training instructor. In July 1957, Glenn achieved fame for setting a transcontinental flight time record by flying from Los Angeles to New York in three hours and 34 minutes.
In April 1959, Glenn was among the seven U.S. astronauts selected to launch into space for Project Mercury. The “Mercury Seven” also included Shepard, Grissom, Wally Schirra, Scott Carpenter, Donald “Deke” Slayton and Gordon Cooper.
NASA’s original plan was to have an open call to select astronauts for Project Mercury, but U.S. President Dwight D. Eisenhower made the decision to use military test pilots instead.
The Mercury Seven were assigned to the Space Task Group based in Hampton, Va.
Over the next few years the group received training in various simulations, parabolic flights, pressure suits, survival skills and communications. They also took academic courses including space science, engineering and physiology. The astronauts were assigned areas of specialty to help design the Mercury capsule.
Glenn was responsible for the layout of the cockpit.
“The astronauts’ specialty assignments had some direct affect on the redesign of the Mercury suit, cockpit layout and the capsule hatch and window systems,” the NASA History Web site said.
Glenn’s flight originally was scheduled for December 1961, but inclement weather and technical problems with the capsule resulted in a series of launch delays. Finally, his Friendship 7 capsule was launched into space the following February.
Aside from a minor error that kept the capsule out of its proper orbital attitude for 38 seconds, the launch and the early part of them flight were nominal.
Glenn noted a dust storm over Africa’s west coast, the electric lights of two cities – Perth and Rockingham, Australia – and the quick onset of sunrise and sunset.
But at the end of the first orbit, Glenn lost control of an attitude control jet, which meant the capsule became like a car with its wheel alignment out of balance, the NASA History Web site said.
Glenn was forced to override the automatic control system – the Mercury capsules were designed to be primarily automated spacecraft – for manual control. He was able to maintain control but could not complete some of his observational assignments, and piloting manually meant the rate of fuel consumption increased.
However, the next reported problem was more serious. A landing-system monitor signaled to the ground that the capsule’s heat shield was not locked into place, meaning it was only being held in place by the overlying retro-rocket package. Without Mercury’s heat shield, the capsule would disintegrate during re-entry – along with Glenn.
After weighing their options, officials at the control center decided that instead of ejecting the retro-rocket package after readying the landing gear as is typically done, they would keep it in place and thus maintain the heat shield, the NASA History Web site said.
Mercury chief designer Maxime Faget approved of that course of action, as long as the retro-rockets were exhausted; any leftover fuel probably would ignite upon re-entry, the NASA History Web site said.
Although not immediately informed of the perceived danger, Glenn became suspicious of a problem when tracking stations kept asking him if his landing-bay deploy switch was turned off, the NASA History Web site said.
“We are recommending that you leave the retro package on during the entire re-entry,” the control center said, according to the 1963 U.S. National Archives documentary film “The John Glenn Story.”
During re-entry Glenn saw the retro-pack breaking into pieces and thought it was the heat shield and that he would be next, according to the NASA History Web site.
Fortunately, he was wrong. Glenn splashed down in the Atlantic Ocean safely after the nearly five-hour flight.
The heat shield was later found to have been locked firmly into place – its sensor simply had malfunctioned.