Gordon Cooper, one of the nation's first astronauts, died on Monday. He was 77. In his post-NASA career, Cooper became known as an outspoken believer in UFOs and charged that the government was covering up its knowledge of extraterrestrial activity.
(CNN) -- Leroy Gordon Cooper, one of the nation's first astronauts who once set a space endurance record by traveling more than 3.3 million miles aboard Gemini 5 in 1965, died on Monday, NASA said. He was 77.
Cooper died at his home in Ventura, California.
"As one of the original seven Mercury astronauts, Gordon Cooper was one of the faces of America's fledgling space program. 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 on the space agency's Web site.
Cooper, an Oklahoma native who entered the Marine Corps after graduating from high school in 1945, later became an elite Air Force test pilot at Edwards Air Force Base in California, where he became fascinated with the space program.
By April 1959, Cooper was named as one of the Project Mercury astronauts, following grueling physical and mental tests each candidate had to endure.
At the news conference naming the future of America's space program, Cooper was joined by Alan Shepard, Gus Grissom, John Glenn, M. Scott Carpenter, Walter Schirra Jr. and Deke Slayton.
On May 15 and 16, 1963, Cooper piloted the Faith 7 spacecraft on a 22-orbit mission that concluded the operational phase of Project Mercury.
A little more than two years later, he would set a new space endurance record, serving as command pilot of the eight-day, 120-revolution Gemini 5 mission, which began August 21, 1965.
It was on this flight that he and Charles Conrad traveled a distance of 3,312,993 miles in 190 hours and 56 minutes. Cooper also became the first man to make a second orbital flight.
During his two space flights, Cooper logged 225 hours, 15 minutes and 3 seconds. He served as backup command pilot for Gemini 12 and as backup commander for Apollo X.
In an interview with CNN in 2000, Cooper said in-house politics kept him off the moon flights.
"I would have liked to have gone to the moon. I would have liked to have been one of the crew that landed on the moon but it just didn't work out that way. And I don't, I certainly don't harbor any bitterness or anger"
In addition to his space flights, Cooper logged more than 7,000 hours flying time in jets and commercial aircraft. He retired from the Air Force and NASA in 1970 with the rank of colonel.
After leaving NASA, Cooper served on the boards of directors as a technical consultant to a number of companies in the aerospace, electronics and energy fields. He also was the vice president for research and development for Walter E. Disney Enterprises Inc., from 1974-1980.
In his post-NASA career, Cooper became known as an outspoken believer in UFOs and charged that the government was covering up its knowledge of extraterrestrial activity.
"I believe that these extraterrestrial vehicles and their crews are visiting this planet from other planets, which obviously are a little more technically advanced than we are here on Earth" he told a United Nations panel in 1985.
"I feel that we need to have a top-level, coordinated program to scientifically collect and analyze data from all over the Earth concerning any type of encounter, and to determine how best to interface with these visitors in a friendly fashion"
He added, "For many years I have lived with a secret, in a secrecy imposed on all specialists and astronauts. I can now reveal that every day, in the USA, our radar instruments capture objects of form and composition unknown to us"