A space tragedy that reminds us of the limits to human endeavour

The death toll in the Columbia shuttle disaster was smaller than that counted every day on Britain's roads, and yet the world stopped to mourn and wonder. As with the explosion of the shuttle Challenger shortly after take-off 17 years ago, it is a moment that reaches far beyond the grief of the families of those involved.

The death toll in the Columbia shuttle disaster was smaller than that counted every day on Britain's roads, and yet the world stopped to mourn and wonder. As with the explosion of the shuttle Challenger shortly after take-off 17 years ago, it is a moment that reaches far beyond the grief of the families of those involved.

In part, there is an element of the arena in this. Space flights are one of the few remaining human activities watched in the knowledge that the participants are risking their lives. Even in motor racing, fatalities are now rare. But the dangers of rocket propulsion, airless space and unimaginable velocities – the shuttle was travelling at 12,500mph when it broke up – are so tangible that the mere fact of space travel is rightly regarded with awe.

The bravery of shuttle crews was saluted around the world over the weekend, and we salute them now. Yet there is something more behind the extraordinary response to this accident. The conquest of space is a symbol, not just of American national pride but, vicariously, of human pride in technological achievement. This is less strong now than when John F Kennedy first identified the space programme with the nation's prestige. But it has remained an inspirational declaration of intent: if America, and by extension humanity, puts its full resources behind something, it can be done.

The problem for Nasa has been: since the moon landings, what is it that the manned space programme is intended to achieve? There are three purposes for being in space, and they are, in order of importance: military, commercial and pure science. For a long time the mobilisation of the huge resources of the American government has only been justified by the explicitly military side of the programme, primarily the missile defence shield. But the truth is that it does not require manned space flight. Nor do communications satellites, which are the main commercial use of space; and the need for humans to carry out scientific research in space, in person as it were, has long been controversial. Certainly, the expense has been difficult for any taxpayer-funded enterprise to justify.

Thus the manned space programme was in danger of being reduced to an underfunded, politicised and multinational public relations exercise. Hence the recent lift-off for the first "space tourist", paying his own way, and hence the presence on Saturday of an Indian and an Israeli astronaut.

The remaining shuttles may continue to fly, of course, not least because there are three astronauts on the International Space Station at the moment (although these could be serviced by Russian spacecraft). But it may well be that there will be a scaling down of the programme. Statisticians will point out that this would be an irrational response, and that the US record in space is still remarkably safe. But the programme is not rational; it is symbolic.

An event of this kind is bound to give pause for thought about the costs and benefits of space exploration. It is likely to mark a further stage in coming to terms with the limits of human endeavour. Much of that has happened, of course, in the scaling back since the excitements of moon landings – no one seriously imagines now that they were the prelude, in anything but the longest term, to human colonisation of space. The romance is fading.

If that contributes to a subtle adjustment to the American psyche, it is likely to be for the better. There can be no harm, in the present world situation, in the US coming to terms with the idea of limits to its power.