LOS ANGELES (AP) _ Gordon Cooper was the last astronaut to take flight during NASA's pioneering Mercury program, but he achieved many key firsts as he piloted Faith 7 capsule in May of 1963.
As he circled the globe 22 times in 34 hours and 20 minutes, Cooper, an Oklahoma native, became the first astronaut in a space flight of more than 24 hours. He was also the first astronaut to sleep in space, and he successfully carried out a beacon experiment that made him the first man to launch a satellite in space.
Cooper, who was the youngest and perhaps cockiest member of the original seven Mercury astronauts, died Monday at his Ventura home of natural causes. He was 77.
Cooper, known as ``Gordo'' to his friends and colleagues, had been suffering from heart problems and showed symptoms of heart failure over the weekend, former Mercury astronaut Wally Schirra said.
``We were probably the most bonded seven men in the history of aviation and space and mankind, and to lose another one is pretty tough for us,'' Schirra told Associated Press Radio.
As one of the nation's first astronauts, Cooper became a hero to a generation of Americans in the early 1960s as the country tried to catch the Soviet Union in the space race.
``He truly portrayed the right stuff, and he helped gain the backing and enthusiasm of the American public, so critical for the spirit of exploration,'' NASA Administrator Sean O'Keefe said.
Cooper, who took a nap in the capsule while waiting for Faith 7 to launch, was the last astronaut to orbit Earth alone.
A serious glitch materialized in Faith 7's final orbits when a short-circuit left its automatic stabilization and control system without electric power. With carbon dioxide levels rising in both Cooper's suit and the cabin, he issued the classic understatement, ``Things are beginning to stack up a little.'' He then radioed that he would pursue a manual re-entry.
Fellow Mercury program astronaut John Glenn, who was the first American to orbit the Earth, recalled that Cooper's onboard clock also was not working properly. Cooper relied on Glenn's voice for a manual countdown for the timing of firing rockets that would ensure landing in the right spot.
``He followed my count and hit the button on 'zero.' It worked; he got back,'' said Glenn, a former U.S. Senator.
Cooper became the first man to make a second orbital flight two years later during the Gemini 5 mission, when he and Charles Conrad established a space endurance record by traveling more than 3.3 million miles in 190 hours, 56 minutes.
The flight proved humans could survive in a weightless state for the length of a trip to the moon and tested a new power source for future flights _ fuel cells. It also let the United States take the lead in the space race by surpassing the Soviet Union in man-hours in orbit.
Cooper's rambunctious attitude was immortalized in Tom Wolfe's book ``The Right Stuff'' and the 1983 movie of the same name.
Cooper gave his signature line during a 1995 reunion of surviving Mercury astronauts. When asked who was the greatest fighter pilot he ever saw, Cooper enthusiastically answered, ``You're looking at him!''
But Schirra said Cooper was not as rowdy as actor Dennis Quaid portrayed him in the movie.
``He's much less emotional and much less flyboy stuff,'' Schirra said. ``He was a nice, steady engineer. He was more of an engineer than a test pilot, actually.''
The death of Cooper came the day that privately built SpaceShipOne broke through the Earth's atmosphere for the second time in five days, capturing a $10 million prize aimed at opening the final frontier to tourists.
Three of the original Mercury astronauts are still alive _ Scott Carpenter, Glenn and Schirra.
Virgil ``Gus'' Grissom died in the 1967 Apollo 1 fire; Donald K. ``Deke'' Slayton died of brain cancer in 1993; and Alan Shepard Jr., died of leukemia in 1998.
Cooper, born March 6, 1927, in Shawnee, Okla., joined the Marines during World War II and transferred to the Air Force in 1949. He earned a bachelor of science degree in aeronautical engineering from the Air Force Institute of Technology in 1956.
He then flew numerous flights as a test pilot in the Flight Test Division at Edwards Air Force Base near Los Angeles. Cooper was selected as a Mercury astronaut in April 1959.
In a May 1963 ceremony at the White House, President John F. Kennedy presented Cooper with the NASA Distinguished Service Medal.
Cooper also authored the 2000 book ``Leap of Faith,'' in which he discussed NASA's early days, his experiences on the Mercury and Gemini missions and his belief in extraterrestrial intelligence. Cooper in the book said that as an Air Force pilot in 1951 that he chased UFOs while based in Germany.
Cooper is survived by his wife, Suzan, and their children.