A novel process to grow edible microalgae on Mars by exploiting in situ-available resources: Experimental investigation. (December 2022) - Fais, Giacomo
Abstract: The achievement of manned missions on Mars is one of the main challenges the humanity is going to face in the next future. In this context, the possibility of growing Spirulina ( Arthrospira Platensis ) intended to produce food for crew members on Mars has been investigated in this work. The experiments have been carried out in a novel device capable to simulate microgravity and an inner atmosphere very similar to the Martian one in terms of chemical composition. This device simulates the conditions taking place within a Martian dome hosting the relevant photobioreactors according to a novel technology recently proposed in the patent literature. The growth medium has been obtained using a mixture, called Martian Medium, consisting of a mixture of Mars regolith leachate and astronauts' urine simulants to verify the possibility of exploiting in-situ available resources and reducing the payload associated to the mission. The obtained results have shown that A. platensis was capable to grow with a good productivity in a medium containing up to 40 %vol of Martian Medium. Moreover, when using this mixture in the developed device the obtained biomass productivity (∼0.048 g L −1 day −1 ) was higher than the one correspondingly gained using optimal growth medium and Earth conditions (∼11 g L −1 day −1 ). Ultimately, the use of Martian Medium in the developed device led to a growth rate much higher than the one achievable on Earth with classical media likely because the CO2 rich atmosphere was capable to avoid carbon starvation phenomena while microgravity conditions reduced settling and aggregation of cells, thus leading to a better diffusion transport of dissolved nutrients to algae. Considered the obtained productivity and astronauts needs it was estimated that by taking advantage of this technology, a culture of about 15 m 3 available within pressurized domes would be sufficient to meet the protein needs of a crew of six members. Highlights: A new technology based on microalgae for food production on Mars was successfully tested. Spirulina grew well in media obtained by mixing leachate of Mars regolith simulants and urine. Spirulina grew well in pure CO2 obtainable by purifying and pressurizing Mars atmosphere. Simulated microgravity had a promoting effect on the growth of Spirulina. Productivity might meet the protein's needs of a crew of six members using only 15 m 3 of culture.