By most accounts, Mars is an inhospitable place: a world frozen solid, blanketed by a mere wisp of atmosphere -- a dry, stark, seemingly lifeless planet. A group of audacious scientists and engineers would like to change that. They have begun to investigate seriously the possibility of transforming Mars into a more Earthlike planet and then seeding life there.
"It was once thought to be so far in the future as to be irrelevant. But all of a sudden, it's starting to look practical," said Christopher McKay, a research scientist at the National Aeronautics and Space Administration's Ames Research Center in California. "We could do it in our lifetime. This is real."
The idea of "terraforming" Mars, as enthusiasts call it, has its roots in science fiction. But as researchers develop a more profound understanding of what makes Earth conducive to life, they have begun to see that it may be possible to create similar conditions on Mars.
But McKay and others have already begun to ask, "Just because we could do it, should we?" To open the debate to a wider audience, McKay and his colleague, biologist Robert Haynes of Toronto's York University, wrote an essay in this month's issue of Scientific American entitled "Should we implant life on Mars?"
"Does Mars have rights?" McKay asked. "It is an interesting question. Is a lifeless planet better than a planet with life?"
"My view is that as far as dropping little packages on Mars to see if it will start something -- I think we would probably create a big mess," said Eugene Hargrove, a philosopher at the University of North Texas in Denton and editor of the book, "Beyond Spaceship Earth: Environmental Ethics in the Solar System."
Hargrove and others find the idea of planetary engineering arrogant. They argue that we don't even know enough about our own planet, let alone Mars. "It really seems weird to me to undertake projects that exceed the life of the people who started them," Hargrove said.
Yet McKay and Haynes argue that implanting life on Mars may not only be possible, but that humans may not be able to resist, given our Promethean tendencies and pioneer spirit.Improving the Atmosphere
There are, however, a few small obstacles to overcome.
By Earth standards, Mars is nippy. Surface temperatures can dip to minus 130 degrees Fahrenheit. Water exists, but it is locked up as permafrost. However, there is evidence that in its distant past, Mars had running water. Probes to the planet have sent back images of what appear to be ancient river beds.
The biggest problem is the Martian atmosphere. Compared to the thick soup of Earth's air, the Martian sky is thin gruel. What little atmosphere there is consists of carbon dioxide, with traces of nitrogen, argon and oxygen. As it is now, this mixture cannot trap enough heat to keep the planet warm.
According to proponents, schemes to terraform Mars would have three parts. First, it must be ensured that life does not already exist there, even in some microscopic form deep in the Martian soil. Second, if there is no life, the atmosphere must be thickened and warmed, which would allow water to melt and release other frozen gases. Third, life would be seeded, perhaps in the form of genetically engineered bacteria or other hardy microorganisms, which would feed on the atmosphere's carbon dioxide and give off oxygen.
In a science fiction novella written several years ago, entitled "The Greening of Mars," British scientist James Lovelock envisioned a time when the Soviets and Americans would end the nuclear arms race and the entire world would end the use of ozone-destroying chlorofluorocarbons, or CFCs.
In addition to destroying Earth's ozone layer, CFCs act as a powerful greenhouse gas, capable of trapping tremendous amounts of heat close to a planet's surface. Molecule for molecule, CFCs trap more heat than carbon dioxide, the most threatening greenhouse gas on Earth. In his novella, Lovelock envisioned humans using their obsolete intercontinental missiles to shuttle millions of tons of CFCs to Mars.
Lovelock wasn't far off. Robert Zubrin, a senior engineer at Martin Marietta Civil Space Systems in Denver, has calculated that it could take as little as 40 years to create enough of a greenhouse effect on Mars to melt the water at the Martian equator and to release the frozen carbon dioxide trapped at the south pole and locked in the Martian soil. He believes about a million tons of CFCs a year could do the trick.
"The interesting thing about the proposal is that the amount of CFCs is within reason," Zubrin said. The Earth currently produces about 650,000 tons of CFCs each year, about 65 percent of the CFCs that would be needed. Zubrin calculates that a network of CFC factories built on Mars could operate on 5,000 megawatts of power, about the same amount used by Chicago.
Of course, hauling all this equipment to Mars would require a colossal effort. But Zubrin thinks his CFC-induced greenhouse effect could produce on Mars an atmosphere about one-third as thick as Earth's, composed mostly of carbon dioxide. In such an environment, humans would not need to wear pressurized suits. "They could walk around in street clothes," Zubrin said. But pioneers from Earth would still need to lug bottles of oxygen, as there would not be enough in the atmosphere.
How quickly could life be established? "If we're talking about tundra, I would say within a century of when the project is begun," Zubrin said. Advanced agriculture would take considerably longer.Just Add Simple Organisms
McKay and Haynes suggest employing simple organisms as a kind of planetary starter kit. "Rough calculations indicate that a microbial ecosystem could be implanted in about 200 years," McKay said.
"If you want to develop an oxygen atmosphere on Mars, you've got to have biology," said Joel Levine, a senior research scientist at NASA's Langley Research Center in Virginia. "The simplest way to do it would be to seed Mars with organisms that take carbon dioxide and water vapor out of the atmosphere and form oxygen as a waste product."
Such a starter kit of microorganisms could take millions of years to produce even the semblance of a simple, primitive Earth. But many scientists believe just such a system was responsible for making the Earth what it is today.
The investigators point out that the studies are in their infancy. Most scientists view the terraformation of Mars more as a "thought experiment" on a computer than a concrete proposal.
"I'm not suggesting that we do it," Levine said, "but we can use the concept to understand the Earth better."
SURFACE TEMPERATURE Earth
Highs usually well above freezing in most places. Lows seldom colder than -10 degrees F except toward poles Mars
Highs usually well below freezing. LOws typically as cold as -130 degrees F
78 percent nitrogen, 20 percent oxygen, 0.9 percent argon, 0.03 percent carbon dioxide Mars
Pressure 1/150th that on Earth; 95 percent carbon dioxide, 2.7 percent nitrogen, 1.6 percent argon, 0.15 percent oxygen
Usually gentle to moderate. 170-mph storms rare and brief Mars
Usually gentle to moderate, but 170-mph storms may sweep planets for weeks
GRAVITATIONAL PULL Earth
1 G Mars
DAY LENGTH Earth
24 hours Mars
24 hours, 37 minutes
YEAR LENGTH Earth
365 days Mars
687 Earth days
TILT OF AXIS* Earth
23.59 degrees Mars
*determines amount of seasonal change during year
"Greenhouse" chemicals sent from Earth could melt water on Mars's frigid surface.