A trip to Mars takes about nine months with current spacecraft. That means astronauts would have to spend a long time on the Red Planet after landing. Supplying them there with life-sustaining consumables is not easy, however, because in addition to the long travel time, safety aspects and transportation costs also figure into the equation. In other words, resources must be both created and recycled on Mars. Biological systems, or bioregenerative life support systems (BLSS), would be the best solution. More specifically, cyanobacteria could be the solution. Humboldt Fellow Cyprien Verseux from ZARM at the University of Bremen, Germany, has now published initial research results in the scientific publication frontiers which indicate that cyanobacteria reproduce excellently under Martian conditions. Thus, they could form the basis for biological life support systems.
We know cyanobacteria primarily as blue-green algae found in lakes during the summer. These bacteria are among the oldest living organisms on our planet and adapt well to many extreme conditions. They grow by absorbing nitrogen and carbon from the air and removing nutrients from the water supplied by agriculture, among other things. While the bacteria can be unhealthy for humans here on Earth in high concentrations, their full potential comes into play on Mars: Through photosynthesis, they produce oxygen, vital for humans and not sufficiently available on Mars. Moreover, unlike other plants, cyanobacteria can grow based on the nutrients present on Mars. Fed by Martian rocks and atmosphere, they would be suitable as the basis for a cyanobacteria-based life support system (CyBLiSS), allowing the crew to draw on local resources, thereby greatly reducing their dependence on Earth, according to Verseux.
A test lab for different atmospheres
But before cyanobacteria can be used on other planets, they must first demonstrate in the lab how they respond to different environmental conditions. A compromise must be found between Mars-like conditions and those that best support cyanobacterial growth. These conditions were created in “Atmos” (Atmosphere Tester for Mars-bound Organic Systems), an atmosphere-controlled negative pressure photobioreactor developed in the “Laboratory for Applied Microbiology” (LASM) at ZARM. Over the past several months, researchers worked to “determine the optimal atmospheric conditions for the growth of cyanobacteria of the genus Anabaena sp while considering technical feasibility on Mars.”
Earth’s atmosphere is 78% nitrogen, 21% oxygen, and a small amount each of argon and carbon. The atmosphere on Mars consists of the same substances, but the composition is completely different: 95% carbon and only small amounts of nitrogen and argon. Oxygen is hardly present at all. In Atmos, the scientists repeatedly changed the proportions of the gases and the ambient pressure and observed the corresponding development of the bacteria. In doing so, they wanted to approximate the Martian atmosphere as closely as possible while at the same time maintaining strong growth in the cyanobacteria. In the end, the cyanobacteria were found to grow excellently in an atmosphere similar to Mars – both in terms of gases (4% carbon; 96% nitrogen) and atmospheric pressure (100 hPa).
In the end, the growth achieved not only met but significantly exceeded expectations, say the researchers. This is promising, they say, in that it greatly facilitates the technical-logistical implementation of a CyBLiSS located on the surface of Mars. “Firstly, because the pressure difference between the inside and outside of the photobioreactor would then be only slight and thus less stringent demands would be placed on the statics of the construction. Second, because it would be possible to generate the required gas from the local atmosphere with minimal processing.” Other missing nutrients for bacterial growth could also be obtained locally from Martian debris (regolith). For example, the team showed that cyanobacteria could grow in the modified atmosphere in water on simulated Martian soil without additional nutrients.
In addition, studies of the resulting biomass showed “that it is suitable as a substrate for subsequent modules of life support systems to generate additional resources on Mars.”
Based on the results of the research, the team is pleased to say that the implementation of a CyBLiSS is moving further into the center of potential Martian life support systems on future Mars missions. However, with these results, work at LASM is just beginning. Over the next few months, Cyprien Verseux and his team plan to refine the CyBLiSS design to the point where they can improve its ability to grow cyanobacteria on Mars. Similarly, they want to improve their use to produce nutrients for biological organisms in subsequent BLSS modules.
Cover photo: Cyprien Verseux makes adjustments to Atmos. © ZARM/University of Bremen