Growing Algae On Mars
It’s a long way to Mars, and explorers headed there will either have to take enough food and supplies to last the whole trip or use in-situ resources to make what they need. A recent ESA Discovery project led by the Universitat de València explored whether microalgae extracted from lichen could survive on Mars and be used to produce oxygen, food and other useful substances.
Although lichens look like single organisms, they contain two or more species living cooperatively together. Each lichen contains a fungus (the mycobiont) in a symbiotic relationship with at least one organism that can photosynthesise (a photobiont) – a green microalga or a cyanobacterium.
Some lichens can survive extremely challenging conditions, including exposure to the space environment. The same applies to the microalgae they contain, which can be extracted and cultivated independently, in a liquid or solid medium. It’s possible, therefore, that they could survive and thrive under Mars conditions and be used to produce resources to support a human presence.
Many species of microalgae found in lichens belong to the Trebouxiaceae family. The ‘Trebouxiaceae as novel candidates to survive in Mars: assessment of their resistance and ability to produce biomass, and derived interest compounds at small-medium scale using in situ resources’ project examined the ability of these lichen microalgae to survive and produce biomass on Mars.
“We don’t really know much about microalgae, even though they are present in environments all over our planet,” says Principal Investigator Marta Pérez-Rodrigo, a PhD candidate at the Universitat de València. “Knowing that they can resist Martian conditions helps us to explore theories of whether organisms could travel from one planet to another. And if we can culture these microalgae in autonomous systems on Mars, or during space missions, then it opens up many possibilities, from providing astronauts with food and oxygen, to protecting them from harmful radiation.”
The results showed that these lichen microalgae can completely withstand individual stresses, including exposure to UV radiation, freezing temperatures (-80°C), simulated Martian soil with high levels of iron oxide and a simulated Martian atmosphere. The microalgae recover rapidly after exposure and return to healthy growth. Some species also tolerate the cellular (osmotic) stress associated with drought or extremely salty water.
The lichen microalgae have molecular mechanisms that allow them to respond to these challenging conditions, including the production of high levels of sugar alcohols. It would be possible to transport them to Mars and maintain them there, and their high nutritional value makes them a good choice for producing food in space.
One step closer to space farming
“This research addresses one of the key challenges for us becoming an interplanetary species,” says Moritz Fontaine, Discovery & Preparation Officer and ESA’s lead for the project. “Even just going to the Moon, we need to understand how living organisms can provide nutritional elements for astronauts or help maintain a closed-loop environmental system.”
The next stage of the research will investigate whether it is possible to use synthetic biology techniques to create new strains of these lichen microalgae that can produce a variety of useful substances.
The project came about as an idea submitted through ESA’s Open Space Innovation Platform, seeking out promising new ideas for space research, and was funded by the Discovery element of ESA’s Basic Activities.
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