According to Nasa’s scientists in Pasadena, Mars is the next best planet for human life besides earth. However, high ultraviolet radiation and low temperatures on the planet’s surface currently impede life’s survival anywhere except in controlled subsurface niches. Many scientists have suggested several ideas to make the Martian surface habitable, but they all involve huge environmental modifications. These suggestions are as interesting as most casino bonuses, but they are well beyond the human capability in the foreseeable future.
Earlier this month, a study published in the “Nature Astronomy” put forward a new approach to make the planet hospitable. The idea is to use an insulating material known as Silica aerogel to make widespread regions of the Martian surface habitable to photosynthetic life. This substance won’t make the entire planet support life, but it can be used in building biospheres or domes to control temperatures and block radiation. However, it will let in enough light for photosynthesis.
Silica aerogel is popular for its incredible insulating properties. The substance features nano-scale networks of interconnected silica clusters, with 97% of it being air by volume. It boasts of the lowest measured thermal conductivities compared to all known materials. Because of that, it has gained prominence in various engineering fields, including designing passively heated buildings on earth.
On Mars, it has demonstrated its effectiveness by protecting electronic equipment on the Mars Opportunity and Spirit rovers from extreme temperature shifts. This substance will also permanently raise the temperatures under the domes to maintain it above water’s melting point. As such, silica aerogel could be used on ice-rich regions on the Martian surface to sufficiently support photosynthetic life with minimal subsequent intervention.
Though blocking UV radiation and raising the surface temperatures are the most critical issues to support life, there are additional constraints. Nutrients availability, atmospheric pressure, and dust deposition need to be considered. However, brines can be useful as they can remain liquid below water’s freezing point, though habitability would be limited to halophilic organisms for high enough salinities.
For plant growth, the high amount of carbon dioxide on Mars is favorable. However, the atmosphere’s low atmospheric pressure means the greenhouse shields would need to be pressurized to minimize water loss. That could place light demands on the structural properties, which can be met by dispersing the silica aerogels with thin layers of an organic polymer or solid transparent material.
Most nutrients are readily available on the surface, with some like sulfur and iron being higher than earth. Nitrogen’s partial low pressure on Mars may be a challenge for unadapted terrestrial microorganisms, though nitrate deposits on the planet may be a plausible alternative source for N2.
For creating local-life in Mars, the most favorable locations are regions that have key resources like surface water and light while minimizing hazards like excessive dust. Luckily, there are lots of mid-latitude locations with near-surface ground ice. Scientists are also planning to test the technology in extreme conditions here on Earth before they can fully replicate it on Mars.
