Terraforming Mars with revolutionary materials

Silica aerogel could warm Mars in a similar way as greenhouse gas warms Earth.

The dream of reshaping Mars to make it habitable for humans moved out of science fiction to science fact in the 1970s, pioneered by the suggestions of the late, great, Carl Sagan.

A 1971 paper authored by the astronomer — who is perhaps best known for his ground-breaking science series ‘Cosmos’ — suggested that vaporizing the northern ice-caps of the red planet could yield around 10 s g/cm² of atmosphere over the planet.

Sagan continues, saying this would result in higher global temperatures as a result of the greenhouse effect and the increased chance of liquid water.

Polar ice caps on Mars are a combination of water ice and frozen CO2. Like its gaseous form, frozen CO2 allows sunlight to penetrate while trapping heat. In the summer, this solid-state greenhouse effect creates pockets of warming under the ice, seen here as black dots in the ice. (Havard SEAS)

Thus, the idea of terraforming Mars became a serious proposition to scientists and futurists. But a serious question remained, hovering over the proposition foiling many a hypothesis.

Would there be enough greenhouse gases and water on Mars to increase its atmospheric pressure to Earth-like levels?

Further to this conundrum, in 2018, researchers at the University of Colorado, Boulder and the University of Arizona found that even if all the available sources on Mars were processed, atmospheric pressure would only be raised to 7% that of Earth. Far short of the level that would make Mars habitable.

Without some revolutionary approach, the dream of terraforming Mars would remain just that; an unfulfilled dream.

That was until researchers from Havard, NASA’s Jet propulsion Lab and Edinburgh University suggested a novel approach. They say that rather than attempt to alter the whole planet to suit our needs, what if we change it regionally?

Laura Kerber, Research Scientist at NASA’s Jet Propulsion Laboratory, says of the idea: “Mars is the most habitable planet in our Solar System besides Earth.”

“But it remains a hostile world for many kinds of life. A system for creating small islands of habitability would allow us to transform Mars in a controlled and scalable way.”

Robin Wordsworth, Assistant Professor of Environmental Science and Engineering at the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) and the Department of Earth and Planetary Science, adds: “This regional approach to making Mars habitable is much more achievable than global atmospheric modification.

“Unlike the previous ideas to make Mars habitable, this is something that can be developed and tested systematically with materials and technology we already have.”

Enter Silica Aerogel and regional approach to terraforming

What makes this new research even more credible is the fact that it was inspired by a process that is already occurring on our solar system neighbour.

Unlike ice-caps on Earth, polar ice caps on Mars are a combination of water ice and frozen CO2. Just like in its gaseous form, frozen CO2 allows sunlight to penetrate while trapping heat. In the summer, this solid-state greenhouse effect creates pockets of warming under the ice.

Wordsworth says: “We started thinking about this solid-state greenhouse effect and how it could be invoked for creating habitable environments on Mars in the future.

“We started thinking about what kind of materials could minimize thermal conductivity but still transmit as much light as possible.”

Silica aerogel may make regional terraforming of Mars a reality

What they concluded was that regions of Mars could be made habitable with the use of a material known as silica aerogel — one of the most insulating materials ever created. The benefit of this remarkable material being it can mimic the effects of Earth’s greenhouse effect.

Silica aerogels are 97% porous, meaning light moves through the material but the interconnecting nanolayers of silicon dioxide infrared radiation and greatly slow the conduction of heat. These aerogels are used in several engineering applications today, including NASA’s Mars Exploration Rovers.

Kerber elaborates: “Silica aerogel is a promising material because its effect is passive.

“It wouldn’t require large amounts of energy or maintenance of moving parts to keep an area warm over long periods of time.”

The researchers' experiments — documented in a paper published in Nature Astronomy — mimicked the surface of Mars and demonstrated that even a thin layer of silica aerogel increases average temperature found at mid-latitudes on Mars to temperatures similar to those found on Earth.

The experiments also demonstrated that a two to three cm thick shield of silica aerogel could transmit enough light to allow photosynthesis to occur, whilst simultaneously blocking hazardous UV radiation. The shield would also raise the temperature underneath it to above the melting point of water permanently without the need for a heat source.

Wordsworth adds: “Spread across a large enough area, you wouldn’t need any other technology or physics, you would just need a layer of this stuff on the surface and underneath you would have permanent liquid water.”

The researchers suggest that the material could be used to build domes for habitation or self-contained biospheres on the surface of Mars.

Wordsworth concludes: “There’s a whole host of fascinating engineering questions that emerge from this.”

Of course, the team acknowledge that before attempting such lofty projects, much more testing is needed.

The next steps to put silica aerogel to the test

The team will now begin taking their tests to regions of Earth that resemble Mars’ surface climate. This means arid areas such as the dry-valleys of Antarctica or Chile.

Before attempting to fulfil Carl Sagan’s dream of terraforming Mars serious ethical questions must be answered (PBS)

Wordsworth is also insistent that before any attempt to terraform Mars are taken into serious consideration, ethical and philosophical questions must be raised.

He says: “If you’re going to enable life on the Martian surface, are you sure that there’s no life there already? If there is, how do we navigate that.

“The moment we decide to commit to having humans on Mars, these questions are inevitable.”