Let the Martians come to us

Even if there is intelligent life out there, let's not take the dangerous and expensive step of trying to reach it, argues Charles Arthur

Daniel Goldin, the head of the US space agency Nasa, is not a man to let the occasion for a few grandiloquent words slip easily by. So he opened Wednesday's press conference in Washington, called to announce some plausible evidence that there was once life on Mars, with a few well- chosen high-octane phrases.

"I have been speaking to world leaders of space," he said. "Some of them were almost childlike in their excitement... I invited them to join us... In the next decade our objective is to send an armada of spacecraft to the other planets in our solar system, and detect planets around other stars."

Following the two-hour exposition - which amounted to a crash course in planetary evolution theory and techniques of scanning electron microscopy - the media were sold on the idea of getting to Mars. So were some of the scientists lined up to speak about their paper.

"We are talking about exploration," one intoned gravely, clearly also stricken with the grandiloquency virus. "It is important that this country keeps its aims of exploration, and the pioneer spirit. There are new worlds to explore in space, but we have to be prepared to invest in them. When we lose that will, such nations perish."

Meanwhile, Bill Clinton, supping the zeitgeist and no doubt with one eye on the feel-good factor in this election year, made a Kennedy-like pronouncement. "I am determined the American space programme will put its full intellectual power and technological prowess behind the search for further evidence of life on Mars," he told an eager group of reporters.

And just for good measure, Mr Goldin wrapped it all up with the declaration: "At the emotional level, we are a very bold nation. Nasa will be ready to take the next step. If we have to take sample missions earlier than expected, we will do it. If we have to dig into the surface of Mars, we will. If we have to do that digging with humans, we will - safely."

Phew. While I had been aware that the US was on a high after its coverage of the Olympics, I hadn't thought they really wanted to enter the interplanetary high jump. My first reaction, listening to those stirring words a safe 6,000 miles away, was that the participants ought to be tested for excess testosterone.

For although Mr Goldin might make it sound as though heading off to Mars would just be a question of getting NBC to do the coverage and inviting a few countries round to help in the competition, the fact is that nobody who matters is in any hurry to get people on Mars - even if this new research is confirmed as correct (which it still hasn't been).

Why the lack of urgency? Because sending people to Mars would be dangerous, enormously expensive, and most unlikely to tell us anything that we cannot find out already, either with robot-driven spacecraft or here on Earth. Don't forget, after all, that this news didn't need any rockets to slip the surly bonds of Earth. We let the Martians do the hard work, travelling through space encased in a chunk of rock that thumped into Antarctica 13,000 years ago, and was discovered only 12 years ago.

Going to Mars sounds so enormously attractive. It's not as obvious as the Moon (I would doubt that many people could point it out in the night sky), but it has the cultural resonance born of hundreds of science fiction films and books. The facts are otherwise. The Moon is 250,000 miles away; it's a few days' journey by any spacecraft. Mars is 46 million miles away, 180 times further. It would take a year to get there and a year to get back. As scientists overwintering in Antarctica have found out, even a few months in enforced close confinement with somebody else can drive you mad, or murderous. "The way someone scratches their beard... it can all add up," said one at a conference in Cambridge this week. Certainly, any childlike excitement that you might start out with would evaporate very quickly.

And besides the psychological problems, there is the difficulty of what they would live on. Carrying enough food and water for a two-year trip would make the spacecraft horrendously heavy: just imagine how much space your own food for a week takes up. Every extra gram must be compensated for with rocket fuel to lift it out of our atmosphere. That's always assuming that no error (as with the Challenger and, more recently, Ariane 5) turned triumph into disaster. Meanwhile, plans to build self-sustaining "farms" that could feed our brave, pioneering, spirited astronauts on their mission are only in the early testing stages. All Bill Clinton's wishes for re- election and Dan Goldin's desire for a willing Congress that will fund him more readily won't change those scientific facts. It will be many decades before we are able to send people to Mars. The cost will also be horrendous, running into tens of billions of dollars.

Beside those points, it's worth asking what we will find even if we do send an armada of highly equipped spacecraft there. Nasa intends to launch two spacecraft this year, costing pounds 265m: one will overfly the red planet, and the other will land and examine the rocks and soil. A mission in 2004 is due to return a sample to Earth, though last week - before this latest announcement - Goldin "challenged" engineers to design systems which could return a sample by 2003.

Quite why we need to bring back the samples in such a hurry is not clear, unless they contain credit cards. It is worth remembering that the US is struggling with a mammoth fiscal deficit that has forced it to cut back public spending on a huge scale - on welfare and health care, most notably. Nasa has not escaped those cuts. Is it really sensible to allow signs of life (which, remember, are not proof positive) to stampede us into spending money that might be better spent on science at home - or even on other humans at home?

It could be that the wisest move would be to keep examining the samples that we have, and to stay with the approach that served us well in this case: let the aliens come to us. But if they do, it might be sensible to be wary.

With 100 billion or so Sun-like stars in the Milky Way, the odds of life having emerged around one, or many, of them is very high. In that case, the odds of other intelligent life having emerged must also be very high. We are presently beaming out signals to space proclaiming our existence: TV programmes from the 1950s have by now passed several thousand stars.

As Malcolm Young, professor in psychology at the University of Newcastle, remarked to me yesterday: "We are presently tweeting loudly like nestlings in a wood in which there may be hungry cats." Biologists, he said, call this a failure of crypticity. Nestlings that survive only make noises when their parents are about to protect them; otherwise they shut up (or get eaten). "Even if the transmissions can't be decoded by our audience, the fact of their existence means there are resources in this system that could be of significant interest."

It starts to sound rather worrying. Some people argue that any aliens that could reach us would already have the capability to destroy themselves - but would have evolved far enough not to use it. Evolution doesn't work that way, Young retorts. "You could say the same about us, but would you like to be a tiger, white rhino, or mountain gorilla?"

It's all reminiscent of the science fiction short story which tells of a race of aliens that comes in peace, ends war, cures disease, and makes humanity stronger, fitter, better. A few lucky people are invited to visit the home planet - a veritable Eden, they are told. The fact that they don't return seems to prove it. One cynic finds an alien book; by enormous effort he manages to translate the title: "To Serve Man". Impressed that altruism really has arrived, he volunteers for the next trip out.

Unfortunately, by the time his number comes up he has translated the first few words. It's a cookery book.