As protagonist Mark Watney quite rightly states in The Martian, our ambitions to establish a human base on the Red Planet will depend entirely on our ability to “science the sh*t out of it.” Taking up that very challenge, researchers have successfully grown algae in Mars-like conditions, potentially paving the way for a life-support system on Mars.
The likes of NASA and SpaceX have made it abundantly clear that they plan to send people to Mars in the near future, yet the logistical challenges of sustaining human life on our neighboring planet are huge. Transporting oxygen and food all the way from Earth would be impractical, so establishing a means of producing these locally is imperative.
A class of microorganisms called cyanobacteria have long been considered excellent candidates for this purpose, as they generate oxygen via photosynthesis while also turning gases like nitrogen and carbon dioxide into nutrients that can sustain plant life. Mars’s atmosphere contains both of these gases, so scientists believe that cyanobacteria could be used to prop up living ecosystems on the Martian surface.
However, because the atmospheric pressure on Mars is just a fraction of that on Earth, liquid water cannot exist and cyanobacteria are unable to grow. Building bioreactors that mimic Earth’s atmospheric conditions could potentially solve this problem, yet would rely on gases transported from our home planet.
The study authors, therefore, sought to investigate if cyanobacteria can be grown using only resources that are available on Mars, thereby eliminating the need to transport materials from Earth.
Writing in the journal Frontiers in Microbiology, they describe the cultivation of a type of algae called Anabaena cyanobacteria in a specially designed bioreactor, which they have labeled Atmos.
Consisting of nine pressure-controlled chambers, Atmos allowed the researchers to grow the cyanobacteria under Mars-like conditions. Importantly, the species was found to grow “vigorously” when cultivated in an atmosphere consisting of 96 percent nitrogen and four percent carbon dioxide, at a pressure of 100 hPa – about one-tenth of the Earth’s atmospheric pressure.
Water was also included in the bioreactor, but this could be obtained on Mars from the abundant ice that covers parts of the planet.
In a statement, study author Cyprien Verseux explained that “cyanobacteria can use gases available in the Martian atmosphere, at a low total pressure, as their source of carbon and nitrogen,” adding that “this could help make long-term missions to Mars sustainable.”
As a next step, the researchers recreated Martian regolith – which is a layer of dust found on the planet’s surface – and used this as their substrate for growing cyanobacteria.
Once again, the algae was found to grow relatively successfully, though not quite as well as it did in more conventional growing mediums. After 28 days, samples grown in a Mars-like atmosphere and regolith produced about half as much chlorophyll as those cultivated under the same conditions but in regular soils.
Finally, the researchers used the resultant Anabaena cyanobacteria as a substrate for growing E. coli bacteria. Such organisms are easily bioengineered and can be used to create certain foods and medicines, but can’t grow on Mars.
Results indicated that E.coli can be grown on dried Anabaena cyanobacteria that has been produced under Martian conditions, indicating that the species could be used to support the growth of other cultures on Mars.
While all of this is pretty exciting, Verseux insists that “our bioreactor, Atmos, is not the cultivation system we would use on Mars: it is meant to test, on Earth, the conditions we would provide there.”
“But our results will help guide the design of a Martian cultivation system.”