Farming on Mars: A future for synthetic biology off Earth

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November 27, 2018

Climate change is rapidly altering the stability of our delicate ecosystem. We face the pressing challenge of providing food for almost 8 billion people even as arable land diminishes. Many scientists look to our home planet to solve this problem. But it might be our quest for the stars which enables us to provide enough food for our growing population.The dream of living on other worlds strips us down to our most basic human needs: breathable air, water, shelter, and of course, food. We already have solutions to the first three problems from the early days of space travel. But, as we turn our ambitions to our nearest neighbor, Mars, the question becomes: how will we sustain ourselves on a planet where nothing grows?Farming on Mars entered the pop culture imagination with Matt Damon’s Oscar-nominated turn as astronaut Mark Watney in “The Martian.” In the film—based on the more-or-less scientifically accurate Andy Weir novel of the same name—Watney survives for 560 days by growing vacuum-sealed potatoes in a combination of Martian soil and human manure. While this solution works in theory as it does as a plot device, it’s hardly practical for long-term human settlement.Researchers have been tackling the big Martian food question long before inspired artists added on a few touches of Hollywood flair. Unsurprisingly, any potential solutions are far more complicated than Watney’s one-man potato farm.Briardo Llorente, a scientist working with Macquarie University, Sydney and Commonwealth Scientific and Industrial Research (CSIRO) spoke at the annual SynBioBeta conference about the complexities of Martian farming.

The challenges of growing crops on Mars

The most obvious obstacle Earth crops face on Mars is that, well, it’s Mars. Our crops have evolved for our gravity, atmospheric pressures, and levels of UV radiation. Earth plants need well-hydrated, bacteria-rich soil, regular sunshine, and generally balmy temperatures.Meanwhile, Mars is an arid, frigid, lifeless, desert with only about half our level of sunlight. It is also bombarded daily by higher levels of UV radiation, although how much radiation is not yet clear.Given these detrimental factors, at first glance, it may seem easier to send food from Earth. But the inter-planetary shipping costs alone are laughably prohibitive. It costs about $10,000 just to send a can of Coke. Even if costs dropped dramatically, any re-supply issues or delays could leave Martian settlers stranded and starving, not unlike the fictional Mark Watney.Fortunately Mars is not completely without resources. Water is stored in the form of polar ice caps and at least one recently discovered underground saline reservoir. Studies also show that plants are able to grow in Mars’ thin topsoil. But, because this is Mars and nothing is easy, any future crops will need a lot more than water and dirt.Crops need habitats with breathable air, radiation protection and steady temperatures and pressure to survive. But, of course, humans need all of these things as well. Creating Earth-like conditions for both plants and humans would strain limited water and energy reserves. It would be a poor settlement plan if we competed for resources with our own food supply.

Using synthetic biology to create Martian-adapted crops

So, reasoned Llorente, why not use synthetic biology to create crops better adapted to Martian conditions? Plants could be engineered to use less water, produce greater yields and have a higher tolerance to cold. The very architecture of the plants could be altered.

Synthetic biology

Synthetic biology applied for enhancing plant performance. Different traits that can be engineered simultaneously to take full advantage of plants on Mars (and Earth). Credit: The Multiplanetary Future of Plant Synthetic Biology

According to Llorente, the best way to test these ideas is in a bio-foundry that mimics Martian conditions. (Happily, the one thing we can’t simulate on Earth—Mars’ lower gravity—doesn’t seem to be an issue for plants. Research shows that plants are happy in little or even no gravity.) Llorente, along with Thomas C. Williams and Hugh D. Goold, detailed their bio-foundry proposal as well as potential crop alterations in an article for Genes, published earlier this year.One of the most innovative ideas Llorente shared at SynBioBeta 2018 was re-engineering how plants harvest energy. Earth plants have adapted to only use visible light. This presents an issue, given the low intensity of Martian sunlight. But with synthetic biology, plants could be altered to harvest UV photons for photosynthesis.This would be a major boon on multiple levels. Improved photosynthesis typically translates to higher crop yields. Even more importantly, plants would require less artificial lighting, giving human settlers a larger energy allowance.

Synthetic Biology

Schematic roadmap for research on adapting life to Mars. The Mars Biofoundry integrates the design of synthetic biology approaches (A) with an automated platform for implementing bioengineering designs in plants and microbes (B) and a facility for high-throughput phenotyping under simulated Martian conditions (C). The process iterates as a design-build-test cycle. Eventually, engineered organisms could be periodically transported to Mars (D) to perform experiments within miniature growth facilities (E). Remote monitoring of performance on Mars (F) would provide critical knowledge to adjust the work carried out at the biofoundry on Earth. Credit: The Multiplanetary Future of Plant Synthetic Biology

To be clear, the crops Llorente and his fellow co-authors envision are not acres of Mark Watney-style potatoes. Nor are they any other traditional type of Earth produce. Waving fields of Martian wheat is currently well outside the realm of possibility. The more reasonable, feasible path to sustenance on Mars is to use good old hardy microbes.

Microbial crops: The future of life off (and on) Earth

The ideal microorganism candidates are yeast and algae. Both can readily withstand harsh conditions on Earth and are relatively easy to engineer. They are nutritious, reproduce rapidly, and take up far less space than traditional crops.

Plant Synthetic Biology

Engineering microorganisms to facilitate plant life on Mars. This conceptual microbe scavenges atmospheric hydrogen (H2) and carbon dioxide (CO2), and it is customized to condition Martian soil for plant growth by reducing soil perchlorate salts (MgClO4 and CaClO4) and increasing soil moisture. H2O: water; Cl−: chlorine; Ca2+: calcium; and Mg2+: magnesium. Credit: The Multiplanetary Future of Plant Synthetic Biology

Large-scale microorganism farms, on Earth or Mars, are still being studied and developed. Products containing algae protein powders are already available in grocery stores. It may not be long before we see algae garden burgers and other algae-based meat substitutes. But the threats of climate change coupled with our other-worldly aspirations may one day lead us to a relaxing algae bacon with eggs breakfast, watching the Martian sunrise.

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