The last space shuttle mission is preparing to leave the Earth; the fleet is being mothballed after nearly three decades of service. We will likely not see their kind again: complicated, deadly machines with engineering more advanced than their epoch should have allowed. Long after the Cold War had been won and the flames of the space race had begun to die down, they remained - a reminder of the lengths to which superpowers were prepared to go in an effort to demonstrate technological superiority over their rivals.
The shuttle programme has served as a convenient hook on which we have hung a course in space medicine and physiology; allowing us to bring the physiology of extreme environments to life while reminding undergraduates of the political and historical context within which this science and technology was forged.
Over the years, we've come to take the space shuttle fleet for granted, its succession of launches becoming at best a footnote at the end of the evening news. What was once a marvel became part of the everyday backdrop to our supper-times.
In part, this is what the shuttle programme was supposed to achieve. It was hoped that humans might access the frontier of space as routinely as they do the polar regions, the ocean depths or the mountain tops of the Earth. And at the advent of the programme, the hope that vehicles blasting into space might one day become as unremarkable as the flight of a jet airliner must have appeared well within reach. Programme managers spoke of expected failure rates of no more than 1 in 100,000, suggesting, as Richard Feynman later pointed out during the Challenger accident investigation, that the shuttle might fly every day for 300 years without mishap. Hard experience would teach us a different lesson, with catastrophic accidents occurring at more than a thousand times that rate.
In retrospect, perhaps we should not have been so naive as to believe that human space exploration might so quickly become routine. A space shuttle is the most complicated vehicle in the history of rocket science. It goes from nought to 25 times the speed of sound in eight minutes, borne aloft on a system of solid and liquid fuels with the explosive capacity of a small nuclear weapon. Having survived the violence of that launch, it is designed to orbit the Earth at 17,000 miles per hour, for days on end, supporting and protecting its human crew while they go about their business. Then, when it's time to come home, it bleeds off that huge burden of kinetic energy, generating temperatures so high during re-entry that a trail of plasma heralds its return. And finally, the landing: gliding home to the Cape, unpowered, falling out of the sky seven times as fast as a commercial airliner, flying, if you ask the shuttle pilots, like a safe with its door open.
But it took catastrophes to re-inject the shuttle programme into the public consciousness. The Challenger and Columbia accidents reminded us that human space flight is an endeavour fraught with risk and made us question precisely what prize was worth that price.
The shuttle served to enable an ambitious programme of science and exploration, to extend human frontiers and to prepare us for greater adventures. Through it, we gained a much clearer understanding of the effect of space flight on the human body and launched space-borne telescopes that literally changed the way we saw the Universe. But as a way of doing science, it proved less than efficient; and as a vehicle for inspiration, its star eventually began to wane.
The full extent of what humankind gained from 30 years of space shuttle missions will likely not be known for some time. It is a tapestry that can't be easily unpicked, transcending science and engineering and spilling over into geopolitics, society and culture. The programme followed on from Project Apollo, a sort of unexpected grandchild of the Cold War. It flew on while the Berlin Wall fell and the Soviet Union collapsed. When the Cold War came to an end, it saw US marines fly in space alongside Russian pilots they had been trained to kill. The space shuttle programme allowed the International Space Station to be built, and it bore witness to the horrors of 9/11 from orbit.
All this it did at great expense, costing many billions of dollars and 14 astronauts' lives.
But asking what the space programme ever did for us is kind of like asking the same of the Romans. It has a place in history that is bigger than the science and the technology, greater than the spin-offs and the peer-reviewed papers.
Our course at University College London, in space medicine and physiology, is about ideas: ideas that are big enough to make students stop and think for a while, big enough to propel them on to the next challenge - whatever that might be. That, I would hope, is worth at least something.
It is unclear what the space shuttle era will finally come to represent. Whether this time will be remembered as the epoch during which our first stuttering human steps into the frontier of space were made or as a glorious aberration after which we fell for ever back to Earth, remains to be seen.
But for now we wait while the last mission prepares to leave. I, for one, will miss it when it's gone.