Skip to Content
Space

We might grow plants on Mars by warming the ice caps with “frozen smoke”

Using silica aerogel to trap heat and create liquid water sounds far-fetched, but it could one day be used to help us grow food on the planet’s surface.
A photo of the mars surface
A photo of the mars surface
A photo of the mars surfaceNASA/JPL-Caltech

The idea of Mars as a kind of “Plan B” for humankind has firmly lodged itself into our cultural consciousness. As imagined in Kim Stanley Robinson’s epic Mars trilogy chronicling humanity’s settlement and terraforming of the planet, we’d need to make Mars’s surface a lot warmer to stand any chance of moving in permanently.

It would be a huge challenge. Mars’s atmosphere is mostly carbon dioxide, but it’s too thin and cold to support liquid water, a crucial ingredient for life. It’s also exposed to dangerous levels of ultraviolet radiation. 

NASA has concluded that warming up the whole planet is unrealistic, as the technologies needed to do so (like the space mirrors imagined in Robinson’s Green Mars novel) don’t exist yet, and Mars doesn’t have enough carbon dioxide trapped in its surface to thicken its atmosphere sufficiently anyway.

However, a new study in Nature Astronomy suggests that applying silica aerogel—a synthetic, porous, ultralight solid material derived from a gel—to certain areas of Mars’s ice-rich poles could replicate this effect on a much smaller scale. A layer of the material two to three centimeters thick could simultaneously block UV radiation, raise temperatures below so that the ice melts, and allow enough visible light through for photosynthesis to occur.

dark spots on Mars that are believed to form due to the solid-state greenhouse effect
The dark spots on Mars are believed to form due to the solid-state greenhouse effect.
Harvard University's John A. Paulson School Of Engineering And Applied Sciences

“Instead of trying to change Mars’s whole atmosphere, we’re suggesting replicating an Earth-like environment in a few centimeters, which would be far more achievable,” says Robin Wordsworth, a planetary scientist at the Harvard School of Engineering and Applied Sciences and coauthor of the paper. Rather than terraforming the whole planet, their proposal would effectively do so regionally, although it would take several years to work.

Why silica aerogel? It’s an extremely good thermal insulator, it’s very light (it is 99.8% air), and it can also transmit plenty of light if it’s thin enough. “There’s no other material like it out there,” says Wordsworth. The material—nicknamed “frozen smoke” because of its ethereal appearance—is already on Mars now, being used to insulate NASA’s Curiosity rover. 

The research team did a series of experiments to test their theory, creating a layer of silica aerogel particles and another of silica aerogel tiles. These were then exposed to light from a lamp (to simulate the sun’s rays), with the temperature change recorded by tiny sensors. The team tweaked the thickness of the aerogel layer until at 2.5 cm (around one inch) it was able to warm the ground beneath by around 50 °C (120 °F). This would be enough insulation to melt the polar ice and allow liquid water to exist throughout the Martian year.

Silica aerogel in particle and tile form
Silica aerogel in particle and tile form

Silica aerogel in particle and tile form.

Eventually, if it works, this system could be used to create the soil conditions needed to grow plants. “If that’s their plan, it could be hugely useful to future missions,” says Zach Dickeson, a Mars researcher at the UK Natural History Museum’s Department of Earth Sciences.

In the long term, the plan would be to manufacture silica aerogel on Mars rather than transporting it. That’s not as outlandish as it seems, as both silica and water ice exist in certain regions of the planet, according to Germán Martinez, a staff scientist at the Lunar and Planetary Institute in Houston, who was not involved in the study.

However, this  regional terraforming plan is still deep in the realms of theory. Although we can test it on Mars-like areas of Earth like the Atacama Desert in Chile, there’s no substitute for the real thing. For that, we would have to be patient. NASA plans the first human mission to Mars in 2030.

Deep Dive

Space

supermassive black hole at center of Milky Way
supermassive black hole at center of Milky Way

This is the first image of the black hole at the center of our galaxy

The stunning image was made possible by linking eight existing radio observatories across the globe.

Mapping the atmosphere on Mars can help advance science on our own planet

The Emirates Mars Mission is monitoring and measuring the climate and atmosphere of the red planet, but this effort also helps promote and advance science at a national level.

SpaceX Starship
SpaceX Starship

How SpaceX’s massive Starship rocket might unlock the solar system—and beyond

With the first orbital test launch of Starship on the horizon, scientists are dreaming about what it might make possible— from trips to Neptune to planetary defense.

space tourism concept
space tourism concept

Space is all yours—for a hefty price

Commercial spaceflight is now officially a thing. But is it a transcendent opportunity for the masses, or just another way for rich people to show off?

Stay connected

Illustration by Rose WongIllustration by Rose Wong

Get the latest updates from
MIT Technology Review

Discover special offers, top stories, upcoming events, and more.

Thank you for submitting your email!

Explore more newsletters

It looks like something went wrong.

We’re having trouble saving your preferences. Try refreshing this page and updating them one more time. If you continue to get this message, reach out to us at customer-service@technologyreview.com with a list of newsletters you’d like to receive.