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Geoengineering Mars's surface with nanorods
Neil Baugh
August 21, 2024
TLDR: Using nanorods to geoengineer Mars’s atmosphere and melt its frozen ice (in theory).
Big Takeaways
Mars has water, but it’s frozen solid.
Warming Mars’s surface would make it more habitable and melt the ice.
Artificial greenhouse gasses would be inefficient due to the large amount required and lack of appropriate starting materials on Mars.
High aspect ratio nanorods could block exiting thermal radiation, keeping the heat locked in on Mars’s surface.
Over time, these nanorods could heat Mars’s surface enough to begin melting ice.
The Problem
Mars has water. It’s just frozen solid. To access it and make Mars habitable, people have suggested using artificial greenhouse gasses to heat Mars’s surface, but there’s a limited amount of the required materials on Mars itself.
To get around this issue, this week’s authors suggest using aerosolized nanorods that block heat from leaving Mars’s surface. These nanorods would be derived from materials abundant on Mars (aluminum and iron), alleviating the need to ship them from Earth.
They modeled the possible effect of these nanorods on Mars’s surface temperature over time.
What better opportunity to practice some theoretical geoengineering?
The Solution
One reason Mars is so cold is that it loses heat through thermal infrared radiation (IR) going off into space. The proposed nanorods are designed to block this thermal IR radiation, keeping the heat trapped on Mars.
They proposed using nanorods that are 60 times longer than they are wide and a similar size to glitter (~9 micrometers long). In theory, this shape and size would make the particles scatter the leaving thermal IR radiation. It would also let the nanorods stay in the air longer than natural Mars dust, helping out even more. They found that the nanorods were much more efficient on a per-mass basis than other proposed systems.
The graph above shows the effect of adding these nanorods to Mars’s atmosphere over time. As intended, the surface temperature would increase as the amount of nanorods in the atmosphere increases. As the temp goes up, more and more ice would melt. For reference, the melting point of ice is around 273 K (the temperature units on the graph).
The authors also note that this initial nanorod-driven warming would lead to an increase in atmosphere by releasing ice-trapped gasses. For example, as the ice melts more and more CO2 would be released, causing further warming. This positive feedback loop would help increase Mars’s temperature to a habitable point.
Overall, I thought this paper was a cool example of geoengineering using an alternative approach to the typical pump-greenhouse-gasses-in.
See you next week for more science,
Neil
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