Oct. 29, 1998 It took a scant 36 years, but John Glenn, who flew into orbit only once, returned there aboard the space shuttle Discovery, becoming, at 77, the oldest man to fly in space. NASA had a good, solid scientific reason to send so old an astronaut up: since the side effects of long-term space flight so closely mirror the symptoms of aging disorientation, loss of muscle mass, decalcification of bones there would be a lot to learn by studying the effects of weightlessness on an aged body. Believe that reason? Neither did a lot of other people and you know what? No one cared. Glenn back in orbit was a little like Paul McCartney's having a new baby in his 60s: it made boomers feel as though they were never going to die, and it made a lot of other Americans feel just plain good. For his part, Glenn, the old warhorse, just wanted to do a good job. He did.