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Concept and design of algae photobioreactor for EMCS

Researchers at University of Stuttgart have completed an algae photobioreactor concept and design for future algae research in Space.

As higher plants, algae can produce oxygen and food based on light and carbon dioxide, and can be used as a basis for future regenerative life support systems for long-term missions in space. The modularity of the European Modular Cultivation System (EMCS), currently being used for life science research onboard the International Space Station, offers the possibility of upgrading and exchanging different units. As part of the TIME SCALE project, the Insitute of Space Systems of the University of Stuttgart has been working on concepts and designs of an Algae Cultivation Chamber that can exchange the currently installed Plant Cultivation Chamber of the EMCS.

Two algae photobioreactor designs

To offer the possibility of versatile algae research in Space, Jens Bretschneider, Gisela Detrell and Stefan Belz have designed two different photobioreactors concepts. The designs are both based on the initial, joint work by the TIME SCALE partners discussing EMCS modularity and the physical and biological constraints and requirements. The first design allows for algae research related to applications in life support systems under Space conditions. The other design emphasizes on more fundamental biological research on algae cells and colonies.

The first design of an algae photobioreactor for the EMCS allows for algae research related to applications in life support systems under Space conditions. Illustration: University of Stuttgart.

The concept for research on algae-based life support systems is based on each Algae Cultivation Chamber having four algae photobioreactors that are based on recirculating water and nutrient liquid in which the algae grow. The reactors support long-term cultivation of algae with the possibility of monitoring how much carbon dioxide is consumed and how much oxygen is produced by the algae. Initial simulations illustrate the foreseen algae growth and gas exchange. For more fundamental biological science experiments, an alternative design is based on small cassettes in which the algae is grown on agar.

Both concepts exploit the possibility offered by the EMCS rotors of providing a desired gravity, spanning from microgravity when not rotating and up to 2.0 g. In a typical experiment, one rotor can be standing still to provide microgravity conditions, while the other can rotate at 59.5 rpm providing gravitational conditions as experienced on Earth (1.0 g). Gravitational levels can be set to meet the scientific requirement of the selected experiment, for example to simulate plant growth at Martian gravity of 0.376 g.