Life (and Death) on Mars
By PAUL DAVIES
SYDNEY, Australia - President Bush's announcement yesterday that the United States will soon be pointing its rockets toward Mars will doubtless be greeted with delight by space scientists.
After all, there are plenty of good reasons to mount such a trip. For a start, Mars is one of the few accessible places beyond Earth that could have sustained life. Though a freeze-dried desert today, it was once warm and wet, with lakes, rivers, active volcanoes and a thick atmosphere - all conditions conducive to life. Microbes might even remain alive there, lurking in liquid aquifers deep beneath the permafrost.
If life began from scratch on both Mars and Earth separately, then evidence for a second genesis would await us, providing a heaven-sent opportunity to compare two bio-systems and learn how life emerges from non-life. And if life were found to have started twice within the solar system, it would signal that the laws of nature are inherently bio-friendly, implying a universe teeming with life.
An alternative possibility is that life started on Mars and spread to Earth inside material blasted into space by the impact of comets crashing into the Martian surface. Mars and Earth trade rocks, and hardy bacteria could have hitched a ride to seed our planet with microbial Martians. Just possibly the journey was reversed, with life starting on Earth and hopping to Mars. Though such cross-contamination would compromise hopes of identifying a genuine second sample of life, it would still represent a biological bonanza, enabling scientists to study two versions of evolution. The economic and practical benefits would be incalculable.
Mars is alluring in another respect. Alone among our sister planets, it is able to support a permanent human presence. As Robert Zubrin of the Mars Society has remarked, it is the second safest place in the solar system. Its thin atmosphere provides a measure of protection against meteorites and radiation. Crucially, there is probably the water, carbon dioxide and minerals needed to sustain a colony.
And yet the scientific community's enthusiasm will surely be tempered by skepticism. Scientists, it's worth remembering, rejoiced when President George H. W. Bush unveiled a Mars project in 1989. The same scientists then despaired when the plan quickly evaporated amid spiraling projected costs and shifting priorities. Of course, the project's demise should not have surprised anyone. Back then, a manned expedition to Mars came with a price tag of of more than $400 billion, a sum that makes the cost of the Apollo Moon landings seem like small change.
Why is going to Mars so expensive? Mainly it's the distance from Earth. At its closest point in orbit, Mars lies 35 million miles away from us, necessitating a journey of many months, whereas reaching the Moon requires just a few days' flight. On top of this, Mars has a surface gravity that, though only 38 percent of Earth's, is much greater than the Moon's. It takes a lot of fuel to blast off Mars and get back home. If the propellant has to be transported there from Earth, costs of a launching soar.
Without some radical improvements in technology, the prospects for sending astronauts on a round-trip to Mars any time soon are slim, whatever the presidential rhetoric. What's more, the president's suggestion of using the Moon as a base - a place to assemble equipment and produce fuel for a Mars mission less expensively - has the potential to turn into a costly sideshow. There is, however, an obvious way to slash the costs and bring Mars within reach of early manned exploration. The answer lies with a one-way mission.
Most people react with instinctive horror at the suggestion. I recall my own sense of discomfort when I met an aging American scientist who claimed to have trained for a one-way mission to the Moon in the pre-Apollo days. And in the case of the barren Moon, that reaction is largely justified. There is little on the Moon to sustain human life. Mars, however, is a different story. Because of the planet's relatively benign environment, it is theoretically able to support a permanent human presence. If provided with the right equipment, astronauts would have a chance of living there for years. A one-way trip to Mars need not mean a quick demise.
Every two years the orbit of Mars creates a window of opportunity to send fresh supplies at a reasonable cost. An initial colony of four astronauts, equipped with a small nuclear reactor and a couple of rover vehicles, could make their own oxygen, grow some food and even initiate building projects using local raw materials. Supplemented by food shipments, medical supplies and replacement gadgets from home, the colony could be sustained indefinitely. To be sure, the living conditions would be uncomfortable, but the colonists would have the opportunity to do ground-breaking scientific work and blaze a trail that would ensure them a permanent place in the annals of discovery.
Obviously this strategy carries significant risks in addition to those faced by a conventional Mars mission. Major equipment failure could leave the colony without enough power, oxygen or food. An accident might kill or disable an astronaut who provided some vital expertise. A supply drop might fail, condemning the colonists to starve in a very public way.
Even if nothing went wrong, the astronauts' lives would certainly be shortened by the harsh conditions. The lower gravity would create long-term medical problems and the cosmic radiation that penetrates the thin atmosphere is bound to increase the risk of cancer. Add in the debilitating effects of general privation, and the lack of sophisticated medical equipment, and the prospects for longevity look slim.
Would it be right to ask people to accept such conditions for the sake of science, or even humanity? The answer has to be yes. We already expect certain people to take significant risks on our behalf, such as special forces operatives or test pilots. Some people gleefully dice with death in the name of sport or adventure. Dangerous occupations that reduce life expectancy through exposure to hazardous conditions or substances are commonplace.
A century ago, explorers set out to trek across Antarctica in the full knowledge that they could die in the process, and that even if they succeeded their health might be irreversibly harmed. Yet governments and scientific societies were willing sponsors of these enterprises. Why should it be different today?
Who would put their hand up for a one-way ticket to Mars? I work among people who study astrobiology and planetary science, and there is no lack of eager young scientists who would sign up right now, given half a chance. But it would make more sense to pick mature, older scientists with reduced life expectancy. Other considerations, like weight, emotional stability and scientific credentials, would of course have to be factored in.
The early outpost wouldn't be left to wither and die. Rather, it would form the basis for a much more ambitious colonization program. Over the years new equipment and additional astronauts would be sent to join the original crew. In time, the colony would grow to the point of being self-sustaining.
When this stage was reached, humanity would have a precious insurance policy against catastrophe at home. During the next millennium there is a significant chance that civilization on Earth will be destroyed by an asteroid, a killer plague or a global war. A Martian colony could keep the flame of civilization and culture alive until Earth could be reverse-colonized from Mars.
Would NASA entertain a one-way policy for human Mars exploration? Probably not. But other, more adventurous space agencies in Europe or Asia might. The next giant leap for mankind won't come without risk.
Paul Davies, professor of natural philosophy at the Australian Center for Astrobiology, is author of "The Fifth Miracle: The Search for the Origin and Meaning of Life."