John Glenn returned to space on October 29, 1998, as a payload specialist on Space Shuttle Discovery, nearly four decades after he became the first American to orbit the Earth.
In 1995, Glenn was reading Space Physiology and Medicine, a book written by NASA doctors. He realized that many changes that occur to physical attributes during space flight, such as loss of bone and muscle mass and blood plasma, are the same as changes that occur due to aging. Glenn thought NASA should send an older person on a shuttle mission, and thought that it should be him. Starting in 1995, he began lobbying NASA director Dan Goldin for the mission. Goldin said he would consider it if there was a scientific reason, and if Glenn could pass the same physical examination the younger astronauts took. Glenn performed research on the subject, and passed the physical examination. On January 16, 1998, NASA Administrator Dan Goldin announced that Glenn would be part of the STS-95 crew; this made him, at age 77, the oldest person to fly in space. (Wikipedia)
Colonel John Glenn was photographed by Karsh at the Manned Spacecraft Center in New York. See more.