Human Martians: the people who settle the Red Planet may not look like us.

• Author: Cavanaugh, Tim

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To UNDERSTAND why genetic engineering is the only way humanity can conquer Mars and the rest of the solar system, consider what the current version of Homo sapiens will have to endure on a trip to the Red Planet. Any crew dispatched on the 18-to-30-month mission to Mars will face highly elevated risks of cancer, tissue degradation, bone density loss, brain damage, pharmaceutical spoilage, and other health threats. The journey outside Earth's magnetic field will expose astronauts to solar flares and cosmic radiation at levels that have not been surveyed since the end of the Apollo missions (the longest of which lasted just 12 days). Arrival on Mars, a geologically inert body with one one-hundredth of Earth's atmosphere and no shielding from solar radiation, will provide little relief and will probably introduce some secondary radiation risk from solar rays reflected off the Martian surface.

While the worst radiation exposure and microgravity risks can be reduced through bulky shields and equipment, the expense of outfitting such a spaceship does not appear to be within the means of private industry. It is hard to justify spending all that money to investors, given Mars' unattractiveness as a resource or destination. Our second-closest planetary neighbor features no life, no mineral value (the surface of the planet is basically rust), no organic chemistry, no temperate regions, no energy sources, and no canals.

On the plus side, the Jet Propulsion Laboratory's Mars Phoenix robot in 2008 did detect the presence of water molecules. Phoenix also took photos that hinted at the presence of ice below the surface of a planet so forbidding that liquid water evaporates immediately on the rare occasions when the temperature rises above freezing.

That's about as attractive as Mars gets. So why would anybody want to go there?

They might not. Gregory Stock, CEO of My Mercury Risk, a firm that researches the role of genetics in vulnerability to environmental toxins, and an advocate of ambitious genetic experimentation, says rapid improvements in science and communication right here on Earth have made the "inner journey" a more interesting avenue of exploration while making travel to other places less compelling. "You can see what's happened in terms of funding of space programs," Stock says. "Moving out is not at the center of our sense of exploration, of excitement about the future."

As for the possibility of designing humans for...