Wild Type

“How can you terraform long-distance?”

“Robots and microbe bombs.” A gleam of enthusiasm lit Ash’s face. “It’s really cool. Our scientists engineer microorganisms that can build up the atmosphere and fix nitrogen in the soil—.”

“More gene hacking.” Skye sniffed. “Didn’t you learn anything from Spores?”

“Yes. That organisms can thrive even in harsh environments if they have the right adaptations.”

“That’s called evolution. Nature makes everything as it should be, over time.”

Ash grimaced. “We don’t have time.”

“That,” said Skye, “might be the first thing on which we agree.”

– Syzygy Part II: Opposition Effect

*

Last week astronomers announced the discovery of seven planets orbiting the dwarf star Trappist-1, a mere 40 light-years from us–relatively close on the scale of the cosmos. Roughly Earth-sized and placed to possibly harbor water or even life forms, the new planets ignited curiosity around the globe. (For inspiration, check out NASA’s awesome mock travel poster for Trappist 1-e, and a cool article from The Verge about multi-planet systems in science fiction). If the lanets are as Earthlike as we imagine, it’s only a matter of time before someone mentions terraforming: the process of making an alien world habitable for human beings.

From science fiction to just science

The concept of terraforming—literally “earth shaping”—originated in science fiction. Writer Jack Williamson coined the term in a 1942 science fiction story called “Collision Orbit”, and the concept goes back at least to H.G. Well’s 1898 classic “The War of the Worlds”. In my Syzygy series, human survivors on a struggling lunar colony invest their hopes and resources in terraforming Mars as a replacement for the now-uninhabitable Earth. I chose Mars for the story because of its proximity and because its geophysical similarities to Earth make it a popular candidate for such environmental alterations. But how might it occur off the page?

Can you breathe me now?

First we’d have to address the atmosphere. Humans require about a 70/30 mix of nitrogen and oxygen, but Mars’ atmosphere is almost entirely carbon dioxide. A process called microbe photosynthesis—bacteria generating energy from the sun and excreting nitrogen as waste—generated Earth’s atmosphere aeons ago, and could do the same on another world. A team of students from Germany proposed the introduction of cyanobacteria into Mars’ atmosphere, which would convert the CO² into oxygen and make it a more human-breathable mix.  Specially engineered microbes might even do double duty, enriching the soil while releasing essential gases. Genetic engineering is a central theme in Syzygy, so I imply this approach for their terraforming efforts.

A bolstered Martian atmosphere would still need continual replenishment. Since Mars lacks a magnetic field, solar wind sweeps atmospheric gases off into space. This means no air to breathe, no protection from dangerous solar radiation, and no means of climate insulation. Temperatures on Mars average -80 F: not exactly a human-friendly environment. Some would-be terraformers have suggested using the same greenhouse effect currently plaguing Earth to alter Mars’ climate. SpaceX founder Elon Musk famously suggested detonating thermonuclear weapons to melt Mars’ ice caps and stimulate global warming. Melting the poles would, in theory, also create liquid water for human use.

Martians? Maybe.

Even if we succeeded in thickening its atmosphere and adjusting its temperature, could Mars host the kind of carbon-based life needed to sustain human settlers and make the red planet feel like home? Although Martian soil contains most of the necessary elements, it lacks reactive nitrogen, an essential ingredient for plants growth. Dutch scientists found that with the introduction of nitrogen-fixing bacteria—or, ahem, organic fertilizers like castaway astronaut Watney used in Andy Weir’s hit sci-fi novel The Martian—some crops thrive in red dirt. Genetic engineering may also allow us to tailor species for the new environment, as scientists in Syzygy attempt to do.

The many possible methods for terraforming have one thing in common: they will probably take a long time to achieve the desired effects. As physicist Neil deGrasse Tyson quipped, “if you have the power of geoengineering to turn Mars into Earth, you have the power of geoengineering to turn Earth back into Earth.” Regardless of our aspirations to colonize the solar system, we should take care of the planet we’ve got, because preparing another will take a while.

Check out previous posts in the Science of Syzygy series for the real science behind space elevators and lunar colonization.