Independent review

The dilemma has been triggered by the decision of the European Space Agency to press ahead with its Aurora programme, developed to seek out life on other planets, and to work on missions that will lead to the landing of Europeans on the Red Planet by 2030.

These projects promise to galvanise public interest in space science, particularly after the excitement raised by last year's failed attempt to land the Beagle 2 probe on Mars.

Most people now believe the prospect of finding life of another world is the most important scientific question of our age. But the price-tag for Britain's involvement in Aurora - £25 million a year - is set to trigger an intense debate among the nation's science chiefs.

'There is no way we can go ahead with a full involvement in missions to Mars without, ultimately, having to make significant cuts elsewhere in our budget,' said Ian Halliday, head of the Particle Physics and Astronomy Research Council, the nation's main funder of space projects.

'We are going to have to think very hard and very carefully over the next few weeks whether we really want to do this. There is no point in joining up in a half-hearted way. We need to be really committed, but that means spending money.'

The Aurora programme is scheduled to begin in 2006 when work will start on the development of probes, robot vehicles and landers that will be launched every two years towards Mars, and which will culminate, around 2015, in a series of joint US-European missions intended to collect samples of Martian soil and rock and return them to Earth. Manned missions, first the Moon and then Mars, would follow in the wake over the next decade.

But the second phase of a feasibility study - costing £40m - still has to be funded, with Britain being expected to provide £7m. Officials at Esa are now pressing Britain to pay up by the end of September.

'The trouble is that there is no point in paying unless we join up to Aurora as full members. It would be a waste of money otherwise,' added Halliday. 'So we have to decide now if we are going to Mars or not over the next couple of decades. That is not going to be an easy decision to make so quickly.'

Earlier this month Chancellor Gordon Brown pledged extra cash for Britain's science. However, much of it was ringfenced for medical and biological projects. At most, astronomers, space scientists and physicists can expect to get an extra £20m a year. Not enough to fund Aurora, never mind all the other competing research that they want money for, projects that include giant telescopes and a new generation of atom smashers. 'We will have to cut existing work - mainly university research - if we want to go to Mars. It is as simple as that,' added Halliday.

It is this prospect that is about to set off an intense debate among academics and scientists. Is going to Mars worth the money? Opin ion is sharply divided.

'If you want inspiration - for young people, for the public - it's about as good a thing as you can spend it on,' said Professor Heinz Wolff, of Brunel University. 'You can defend Mars missions from the educational point of view alone. There is a tremendous dearth of young people wanting to get into science, because it isn't interesting enough.

'However, it would also be interesting to know if life is unique to Earth or if another heavenly body close to us, like Mars, could independently generate it. The latter discovery would suggest life in the Universe is commonplace. That is why Mars is so important.'

However, naturalist Sir David Attenborough disagreed. 'I think there are many other stronger competitors in scientific research,' he said. 'Astrophysicists might not welcome that, but it is a lot of money and I do think there is an awful lot of other research to be done.'

The dilemma was summed up by Astronomer Royal Sir Martin Rees. 'There is wide public interest in astronomy and space science, but I think interest is captured by many projects. The real question is: would this one be of greater interest than all the other marvellous things we are learning about deep space from our telescopes? I am really not sure myself.'

However, the prospect of Britain's heading to Mars was backed by the fertility expert, Lord Robert Winston. 'We may learn vital things about the solar system that we don't know at the moment,' he said. 'We have to make a judgment against a broad spectrum of science. It's like saying we can't spend money on infertility, we have patients dying of cancer.

'I think the general consensus is that this is a good way of spending their money. We should be looking to try and increase young people going into the physical sciences and this kind of initiative does do that to a very large extent.

	THE GUARDIAN