"GOD speed you John Glenn" was the wish of the anxious NASA technician who helped blast America's first astronaut into space on February 10th, 1962. With black humour the 40-year-old Marine pilot strapped into the cramped capsule was called "Spam in the can".
Tomorrow, if all goes according to plan, it will be a septuagenarian US senator and six crewmates who will be wished God speed as the 10 times roomier space shuttle Discovery lifts off at Cape Canaveral for a nine-day scientific mission.
Glenn's first and only space flight lasted just under five hours before he splashed down in the Caribbean. His achievement thrilled an America which had grown fearful of the Soviet Union's lead in the space race at the height of the Cold War. Glenn became a national hero.
But he was never allowed to go into space again. Some say this was on the orders of President Kennedy, who regarded him as too valuable a national icon to be risked as NASA prepared for the Apollo mission which would put two of Glenn's fellow astronauts on the moon in 1969. President Clinton will be the first US President to be present for a space launch which has caught the American imagination in a way not felt since the moon mission and Glenn's own solo flight in 1962. Some 250,000 sightseers at the Cape will be watching Discovery lift off at 9 a.m. Irish time. This is five times more people than gathered for Glenn's first flight.
While there has been some criticism that Glenn, as a Democratic senator, used his political friendship with President Clinton to badger NASA into allowing him to return to space at 77, the begrudgers have been swept aside in a growing wave of excitement mixed with nostalgia. The veteran TV newscaster Walter Cronkite, who covered the 1962 launch, is coming out of retirement to report this one for CNN.
Glenn's presence on this mission has led to huge media interest worldwide at a time when space shuttle flights have become almost routine. Glenn, who is retiring from politics this year, has been embarrassed at the publicity and has insisted that this is not an ego trip but a genuine scientific experiment.
The effects of weightlessness on his 77-year-old body will furnish valuable data to medical science on the ageing process, Glenn points out. Weightlessness in space causes all astronauts to "age" temporarily as their bones and muscles diminish, their hearts shrink, balance is disturbed and their sleep is disrupted. The monitoring of Glenn's reactions over nine days will help experts to determine what space does to an already old body.
Glenn's training has been arduous over the past nine months as he has had to go through the same tests and exercises as his crewmates, some half his age. On the mission he will be a human guinea pig for a dozen experiments as he wears a harness plastered with electrodes, gives 12 blood samples, swallows a tiny transmitter and works constantly at a computer to test his reactions.
As some of the critics grumbled that these scientific experiments had been cobbled together to justify bringing along the elder senator, another astronaut, Eugene Cernan - the last man to walk on the moon - commented: "I don't care if John just stares out the window for 10 days. He's earned it." There will be little time, however, for staring out the window as Glenn carries out all his duties as a lowly "payload specialist". This will be an international mission, with a Spaniard, Pedro Duque, from the European Space Agency and a Japanese woman heart surgeon, Chiakai Mukai.