Researchers at the University of Bremen, Germany, cultured cyanobacteria at low pressure using only Martian materials. Eventually, this type of technology could allow the creation of oxygen to support the first Martian explorers.
Several agencies and companies such as NASA or SpaceX aim to establish themselves on Mars over the next few years. Given the means of propulsion available and the celestial mechanics bringing the Earth and Mars closer every twenty-six months approximately, we must bear in mind that the first humans who will land on the red planet will remain there for many months before hoping for a return to Earth.
This is obviously a major hurdle as just carrying enough supplies for a mission that could last more than two years would be prohibitively expensive. Indeed, the more weight there is to lift, the more available fuel is needed.
So future Mars explorers will have to rely on local resources as much as possible. This is why mission planners must already develop ways to grow food on Mars to supplement cargo rations or obtain oxygen.
With this in mind, researchers from the Center for Applied Space Technology (ZARM) at the University of Bremen, Germany, looked into cyanobacteria. On Earth, trees generally get all the credit for producing oxygen (a by-product of photosynthesis). However, in reality, it is these bacteria that do the "most of the work".
On Mars, these organisms could also produce oxygen, but also fix atmospheric nitrogen into sugars, amino acids and other nutrients capable of supporting the cultivation of food.
Naturally, the Martian environment is a bit peculiar. The atmospheric pressure of the red planet is indeed only 1% of that found on Earth . However, this is too low to allow the presence of liquid water on the surface in which these algae could develop.
To overcome this, the team produced a bioreactor named ATMOS (Atmosphere Tester for Mars-bound Organic Systems) consisting of nine sterile one-liter glass and steel vessels , heated and controlled to create a pressure equivalent to 10% of that of the Earth. Inside, cyanobacteria (Anabaena) were introduced into a mixture of 4% carbon dioxide and 96% nitrogen with an artificial Martian regolith containing nutrients including phosphorus, sulfur and calcium.
The team tested the reactor with a specific species of nitrogen-fixing cyanobacteria likely to thrive in these conditions. And the results have been positive. The cyanobacteria did indeed thrive less than in a standard terrestrial environment, naturally, but they responded well to this simulated environment. In other words, it could therefore be possible to grow them on Mars relying on local and not imported resources.
Of course, this is just a proof of concept. Further research will therefore be needed to refine the technology. “Our bioreactor is not the culture system we would use on Mars “, notes Cyprien Verseux, who directs this work. “In contrast, our results will help guide the design of a Martian culture system “.
Study details are published in Frontiers in Microbiology.
