Humans Could Warm Up Mars for Space Travelers by Spraying Tiny Metal Rods Into Its Atmosphere

For humans to survive outdoors on Mars, the Martian climate would need to be much different from how it is today. For one thing, the planet gets far too cold to support astronauts—Mars’ median surface temperature is minus 85 degrees Fahrenheit.

In a study published Wednesday in the journal Science Advances, researchers propose an engineering technique for warming up Mars: designing tiny rods from Martian dust that could trap heat in its atmosphere. This strategy to terraform the planet—or alter it to more closely resemble Earth—could be a step toward making Mars more hospitable to humans.

“It’s not that often you get some really quite new, innovative idea for terraforming,” Colin McInnes, a space engineer at the University of Glasgow in Scotland who did not contribute to the findings, tells Science’s Hannah Richter. “The gap between where Mars is and where Mars could be for habitability is narrower than we might think.”

Billions of years ago, Mars was warmer and wetter, and it had a thicker atmosphere. But today, life found on Earth couldn’t survive there. Mars’ temperature ranges from 75 degrees Fahrenheit to minus 225 degrees Fahrenheit. The planet’s thin atmosphere, made mostly of carbon dioxide, can trap little of the sun’s warmth. It also only exerts a small fraction of the pressure of Earth’s atmosphere, so humans would need to wear spacesuits on the surface.

Additionally, water can’t last for long on the surface of Mars because of this thin atmosphere. Water ice exists underground in the planet’s polar regions.

Scientists have previously studied how humans might raise Mars’ temperature, making it more livable. Some theories involve bolstering the Martian atmosphere with heat-trapping compounds. “The general idea is artificially creating a greenhouse,” Samaneh Ansari, first author of the new study and an electric engineer at Northwestern University, says to Science.

One existing idea, akin to human-caused climate change on Earth, involves warming Mars with chlorofluorocarbons, a class of chemicals once widely used in aerosols and refrigerants that have been harmful to our home planet’s ozone. But while they might be effective at raising the temperature of Mars, the Red Planet’s surface doesn’t have many chlorofluorocarbons. So, to execute this plan, people would have to ship huge loads of the compounds from Earth.

In the new study, researchers instead suggest using a material that’s already common on Mars. They propose designing tiny rods—each smaller than a flake of commercial glitter—from aluminum and iron in the abundant dust on the Martian surface. The researchers calculated that in the atmosphere, these so-called nanorods would let sunlight through and trap rising heat, warming the planet. The nine-micrometer-long particles would persist for roughly a decade, settling out of the Martian atmosphere ten times as slowly as Martian dust does.

Computer modeling allowed the researchers to calculate how much warming the nanorods could stimulate and compare it to other strategies. Releasing the nanorods at a rate of 30 liters per second could warm Mars globally by 54 degrees Fahrenheit over the ten-year lifetime of the particles. This would be more than 5,000 times as effective as other proposed techniques, the authors write.

“When we did the calculation, we found a surprisingly small amount of engineered dust would be required, much less than if you wanted the same amount of warming with engineered greenhouse gases,” Edwin Kite, a co-author of the study and planetary scientist at the University of Chicago, tells New Scientist’s Alex Wilkins.

Atmospheric pressure would also increase as the warming thaws carbon dioxide ice and releases the gas into the atmosphere, creating a positive feedback loop.

Despite its relative efficiency, such an effort would still be a massive engineering undertaking—it would require material processing equivalent to 0.1 percent of Earth’s entire metal production each year. And it wouldn’t make Mars habitable on its own—the planet’s atmosphere would still contain little breathable oxygen, and its soil would remain unfarmable due to its high nitrate concentration.

And there’s still the ethical question of whether we should mess with Mars’ environment, even if we can.

“The deep surface of Mars is still barely explored; we don’t know anything about it,” Manoj Joshi, a climate dynamicist at the University of East Anglia in England who was not involved in the research, tells New Scientist. “Should we really be altering a planet in this manner?”

Will Sullivan | | READ MORE

Will Sullivan is a science writer based in Washington, D.C. His work has appeared in Inside Science and NOVA Next.