Donald K. Slayton; Mercury Astronaut

Astronaut Donald K. (Deke) Slayton, who had enough of the right stuff to fly into space at age 51, more than a decade after a heart condition bumped him from a pioneering Mercury space capsule, died Sunday. He was 69.

One of the storied seven original astronauts who launched America’s manned space flight program, Slayton had been under treatment for a brain tumor that went into remission last year but reappeared in recent months, relatives said. Slayton died in his sleep at home in League City, Tex., near Houston.

“We’re all shook up about it,” fellow Mercury Seven astronaut M. Scott Carpenter told the Associated Press. “There’s not much else to say except to mourn the passing of a dear, dear comrade.”

A teen-age World War II combat pilot who went back into active service during the Korean conflict, Slayton was an Air Force test pilot when he was chosen in 1959 to be in the first class of astronauts.

He was set to be the fourth American in space, but doctors grounded him after discovering an irregular heartbeat. Carpenter flew on the May, 1962, Mercury-Atlas mission instead.

Despite the disappointment, which he later blamed on conflicting medical findings and a suspected thumbs-down call from then-Vice President Lyndon B. Johnson, Slayton went on to supervise astronaut activities at the Johnson Space Center, where he was chief astronaut and director of flight crew operations. He was responsible for selection and training of new astronauts.

Finally cleared for flight in 1972, he got his space ride three years later, when he was chosen as one of the three American fliers who circled the Earth with Soviet cosmonauts in the Apollo-Soyuz mission during a lull in the Cold War.

The laconic but straight-talking Slayton raised some eyebrows when he called the joint mission “more of a PR flight than a test flight” and said his Russian crew mates served “a lousy system.”

But he embraced the Soviet fliers after he docked the American craft with the orbiting Soviet space station.

“It’s worth waiting 16 years for,” he said then. The nine days in space went so smoothly, he said, “I haven’t done anything my 91-year-old aunt up in Wisconsin couldn’t have done as well.”

The landing was not so smooth, however, as Slayton and his crew mates scrambled to deal with a brownish-yellow gas that leaked into their capsule during descent. Slayton and commander Thomas P. Stafford put on gas masks and quickly revived astronaut Vance D. Brand, who had lost consciousness.

After several years devoted to managing the space shuttle program, Slayton retired from the National Aeronautics and Space Administration in 1982, the last of the original seven to leave the astronaut corps. He was the president of Space Services, a company that developed rockets for commercial flights and sent satellites into space. It is now a subsidiary of EER Systems. He also raced midget airplanes.

Slayton was born in the farm town of Sparta, Wis., where he boxed in high school because football interfered with the harvest. He joined the Army Air Corps in 1942, winning his wings a year later and flying 56 missions as a bomber pilot over Europe and seven over Japan. He was nicknamed “Deke” by a training officer who had three other Dons in his squadron.

After the war, he earned a bachelor’s degree in aeronautical engineering at the University of Minnesota and worked for Boeing Aircraft for two years before rejoining the service.

Survivors include his wife, Bobbie, and a son, Kent, 36.

Of the original Mercury astronauts celebrated in Tom Wolfe’s book “The Right Stuff,” five survive: Carpenter, Alan B. Shepard, John Glenn, H. Gordon Cooper and Walter M. Schirra.

Virgil (Gus) Grissom died with two other astronauts in a launch-pad fire in 1967.