By Paul Davies
Neil Armstrong's first small step for man was widely believed to be the start of a long and glorious road to the stars. Forty years after the first Moon landing, the dream has faded. Astronauts have been stuck in low-Earth orbit, boldly going nowhere. American attempts to kick-start a new phase of lunar exploration have stalled amid the realisation that Nasa's budget is too small for the job. And last week, a committee chaired by the aerospace engineer Norman Augustine concluded that "no plan compatible with the … 2010 budget profile permits human exploration to continue in any meaningful way".
Clearly, some creative thinking is badly needed if humans are to have a future beyond Earth. Returning to the Moon may be worthy and attainable, but it fails to capture the public's imagination. What does get people excited is the prospect of a mission to Mars. The lure of the red planet lies in its Earth-like conditions and the tantalising prospect of some form of life.
Unfortunately, existing plans are absurdly expensive and will remain unrealistic for decades. But there is a way to put humans on Mars with foreseeable technology, and at a fraction of the projected cost. Five years ago I made the radical proposal that a handful of astronauts be sent on a one-way journey to Mars. I am not talking about a suicide mission. With its protective atmosphere, accessible water and carbon dioxide, and significant amounts of methane, Mars is one of the few places in the solar system that could support a human colony.
By eliminating the need to transport heavy fuel and equipment for the return journey, costs could be slashed by 80% or more. Supplies and a power source would be sent on ahead, and only when everything is functional would astronauts be dispatched. The base would be re-supplied from Earth every two years. Of course the mission would still be highly risky, but so is round-the-world ballooning and mountaineering. The ideal astronauts would be scientists and engineers who could continue to do world-class science while serving as trailblazers for the colonisation of a new planet. Eventually, more people would join them. After a century or two, the colony could become self-sustaining.
The first Martians would have to accept reduced life expectancy due to radiation, lack of advanced medical resources and lower gravity, but a return journey entails similar hazards. Moreover, the most dangerous parts of space exploration are take-off and landing: cutting out the return halves the risk.
I have presented my idea at Nasa conferences, and discussed it with scientists in other countries. The response has nearly always been positive. There is a persistent myth that nobody would volunteer to go. In fact, I have found no shortage of eager scientists, young and old, who say they would accept a one-way ticket. So my proposal makes financial and scientific sense, but it leaves us with the key question: why?
A permanent base on Mars would have a number of advantages beyond being a bonanza for planetary science and geology. If, as some evidence suggests, exotic micro-organisms have arisen independently of terrestrial life, studying them could revolutionise biology, medicine and biotechnology.
Mars would also provide an excellent forward base for exploring and mining the asteroid belt, and developing whole new industries. A self-sustaining Mars colony would serve as a "lifeboat" in the event of a global catastrophe on Earth. In coming centuries, our civilisation faces small but persistent threats from comet and asteroid impacts, world wars, global pandemics and climatic upheavals, any of which could wipe out all humanity. An outpost on Mars would keep the flame of human culture alight even in the worst-case scenario.
Perhaps the best motivation for going to Mars is political. It is obvious that no single nation currently has either the will or the resources to do it alone, but a consortium of nations and space agencies could achieve it within 20 years. A worldwide project to create a second home for humankind elsewhere in the solar system would be the greatest adventure our species has embarked upon since walking out of Africa 100,000 years ago, and provide a unifying influence unparalleled in history. With Nasa's manned space programme back in the melting pot, now is the time to put a one-way mission to Mars at the top of the space exploration agenda.