Mars is a pretty inhospitable place, and NASA recently ruined the fun by showing that it's just not feasible to terraform the entire planet. But what about just certain parts of it? Now, researchers from Harvard have shown that thin layers of silica aerogel could warm the surface and block UV radiation while still letting visible light through. That could be enough to keep water liquid and let plants photosynthesize within a given region.
While Mars was once a lush, watery world that could have supported life, that's definitely not the Red Planet we know today. Modern Mars is a dried-up husk, with the only water still there locked away in either the polar ice caps or salty lakes deep underground. The thin atmosphere means that there's very little oxygen, it's extremely cold and there's no protection from UV radiation from the Sun.
The new Harvard study could solve at least a few of those problems, thanks to silica aerogel. It's one of the lightest materials ever created, transparent, and an excellent thermal insulator. All of this means that, at least in theory, a thin layer of silica aerogel in the Martian sky could effectively terraform a small patch of ground below it. This would make the surface warmer, and reflect UV radiation away without blocking visible light.
The researchers tested the idea by recreating the surface conditions of Mars in the lab, and placing a silica aerogel layer over the top to see what changes it could trigger. Incredibly, they found that a very thin layer – just 2 to 3 cm (0.8 to 1.2 in) thick – could be enough to warm the underlying surface by as much as 50° C (90° F).
If done in the right place, that could bring the surface temperature of Mars up to -10° C (14° F) – still on the chilly side, but potentially liveable. And it might be even toastier than that: in the paper the team says "the peak obtainable warming is likely even higher, because heat is lost in our experimental set-up via sidewall and base thermal losses and convection."
The team then tested the idea using a climate model of Mars. That showed that putting silica aerogel in the air above an icy, temperate region of the Red Planet could keep water in a liquid form at the surface, and a few meters below, all year long. Plants and other life could survive under that shelter, which still gives them plenty of light for photosynthesis while protecting them from UV damage.
As intriguing as the idea is, the team acknowledges that there are still astrobiological risks to be considered before silica aerogel can be used on Mars. In the meantime, the researchers suggest testing it out here on Earth, in extreme environments like deserts.
The research was published in the journal Nature Astronomy.
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