For decades we have thought about how to modify the Martian climate so that it makes the red planet habitable for humans. Carl Sagan was the first outside the field of science fiction to propose terraformation. In a 1971 article, Sagan suggested that the vaporization of the ice sheets of the North Pole “would produce higher global temperatures through the greenhouse effect and a much higher probability of liquid water.”
Sagan’s work inspired others, but the key question is: are there enough greenhouse gases and water on Mars to increase its atmospheric pressure to levels similar to those on Earth? A team of scientists from Harvard University, NASA and the University of Edinburgh have a new idea. Instead of trying to change the entire planet, what would happen if we adopted a more… regional approach?
Experts suggest that the Martian surface regions could be made habitable with a material, the silica airgel, which mimics the Earth’s atmospheric greenhouse effect. According to the study, published in Nature Astronomy, a shield two to three centimeters thick could transmit enough visible light for photosynthesis, block dangerous ultraviolet radiation and raise temperatures below the melting point of water permanently, all without the need for an internal heat source.
To develop this idea, scientists were inspired by a phenomenon that already occurs on Mars.
Unlike the polar ice sheets on Earth, which are made of frozen water, the polar ice caps on Mars are a combination of ice water and frozen CO2. Like its gaseous form, frozen CO2 allows sunlight to penetrate while trapping heat. In the summer, this solid-state greenhouse creates hot spots under the ice.
“The silica airgel is a promising material because its effect is passive,” explains the co-author of the study Laura Kerber. “It does not require large amounts of energy or the maintenance of moving parts to conserve a hot area for long periods of time. Mars is the most livable planet in our Solar System, after Earth. But it is still a hostile world for many types of life. A system to create small islands of habitability would allow us to transform Mars in a controlled and scalable way.”
“This regional approach to making Mars habitable is much more feasible than global atmospheric modification,” explains Robin Wordsworth, co-author of the study. “Unlike previous ideas to make Mars habitable, this is something that can be systematically developed and tested with the materials and technology we already have. Distributed in an area large enough, we would not need any other technology, just a layer of airgel and we would have liquid water permanently. ”
The next step is to test the material in climates similar to those of Mars on Earth, such as the dry valleys of Antarctica or Chile.