Are there life supports on Mars

Cyanobacteria could thrive on Mars and produce oxygen

Cyanobacteria feel at home even under the most inhospitable conditions, which could give them a role in space travel in the future: A team led by Cyprien Verseux from the Center for Applied Space Technology and Microgravity (ZARM) at the University of Bremen has discovered evidence that Cyanobacteria reproduce excellently even under Mars conditions and could thus form the basis for biological life support systems.

An expedition to Mars would take years - the journey alone takes at least nine months, depending on the planetary constellation. Continuously supplying the astronauts with life-sustaining consumables for such a long time is only one of many problems to be solved. Actually, long-term exploration missions can only succeed if the most important resources on Mars are produced and recycled.

One solution for this would be bioregenerative life support systems (BLSS) based on cyanobacteria. Their full potential comes into play on Mars, as they can adapt well to many extreme conditions and produce oxygen through photosynthesis. This ability can be found in almost all plants, but cyanobacteria can also grow on the basis of the nutrients that are available on the red planet, according to the scientists

Atmospheric test laboratory

In order to make use of cyanobacteria on other planets, the first step is to research in the laboratory how they react to different environmental conditions: A compromise has to be found between Mars-like conditions and circumstances that best support the growth of cyanobacteria. With the help of an atmosphere-controlled negative pressure photobioreactor, the "Atmos", the research team has been working in the last few months to determine the optimal atmospheric conditions for the growth of the cyanobacteria of the genus Anabaena, while at the same time taking into account the technical feasibility on Mars.

The earth's atmosphere is made up of nitrogen (78 percent) and oxygen (21 percent) as well as a small amount of argon and carbon. The Martian atmosphere, on the other hand, consists of the same substances, but has almost the opposite composition, as it consists mainly of carbon (95 percent) and only small proportions of nitrogen and argon, and possibly contains traces of oxygen.

In the experiment, the proportions of the gases and the ambient pressure were changed in various runs and the corresponding development of the bacteria was observed. The aim of the investigations was to get as close as possible to the Martian atmosphere while at the same time a strong growth of the cyanobacteria is maintained.

Unexpectedly strong growth

The results published in the journal "Frontiers in Microbiology" turned out to be very promising: The scientists were mainly able to demonstrate that the cyanobacteria reproduced excellently when they are exposed to an atmosphere that is not dissimilar to the Martian atmosphere - both with regard to the Gases (4 percent carbon; 96 percent nitrogen) as well as atmospheric pressure (100 hPa). The growth achieved has even significantly exceeded expectations. This is promising insofar as it considerably facilitates the technical and logistical implementation of a BLSS based on cyanobacteria on the surface of Mars, a "CyBLiSS".

On the one hand, because then the pressure difference between the inside and outside of the photobioreactor is only small and therefore less high demands are placed on the statics of the construction. On the other hand, because it would be possible to generate the required gas phase from the local atmosphere with minimal processing. Other missing nutrients for the growth of the bacteria can also be obtained on site from Mars rubble (regolith): The team showed that the cyanobacteria could grow in the modified atmosphere in water on a simulated Martian soil without additional nutrients. As a further research result, the investigations of the resulting biomass have shown that it is suitable as a substrate for subsequent modules of life support systems in order to generate further resources on Mars. (red, February 21, 2021)