A thin layer of silica aerogel could be used to insulate the surface of Mars, thereby helping to sustain liquid water year-round and protect from harmful ultraviolet (UV) radiation, reports a Nature Astronomy paper. This approach could potentially allow photosynthetic life to develop on Mars without extensive planetary-scale modifications.

The conditions of the Martian surface are hostile to terrestrial life. It is too cold to maintain liquid water and there is no ozone layer to protect from UV radiation. Several proposals to make Mars more habitable have been suggested, but such ‘terraforming’ projects would be expensive and impossible with current technologies.

Robin Wordsworth and colleagues replicated the surface conditions of Mars in laboratory experiments. They showed that a 2 - 3 cm layer of silica aerogel can increase the temperature of the underlying surface by 50 °C. The authors then used a climate model of Mars to confirm that silica aerogel in ice-rich temperate regions could keep the water liquid up to a depth of several metres throughout the Martian year. In addition, silica aerogels transmit visible light while absorbing it at UV wavelengths, protecting the planet’s environment below, while still allowing enough light for photosynthesis.

The authors note that since silica aerogel is already being manufactured, it is ready to be further tested in extreme environments on Earth. However, they stress that the astrobiological risks of using the material on Mars will need to be understood.