Development and evaluation of a conceptual design for cultivating chlorella vulgaris in microgravity within a CubeSat payload

Abstract

In recent years, platforms in Low Earth Orbit have become increasingly valuable for scientific research, as the microgravity environment enables studies that cannot be performed under terrestrial conditions. Despite this potential, the design of payloads remains challenging due to high costs, stringent safety requirements, limited power and volume, and complex integration procedures. This thesis, carried out in collaboration with Tumbleweed Microgravity, explores the adaptation of the company’s sealed, fault-isolated payload container, Pod, to support experiments with living organisms during a one-month Sun-Synchronous Orbit mission.

A conceptual design was developed to cultivate Chlorella vulgaris and assess its capacity for hydrogen production in microgravity. The study highlights several key limitations resulting from the compact payload design and restricted resources. The small culture volume (two 10 mL vials) limits both nutrient availability and experiment duration, while the tight power budget constrains the simultaneous operation of the heating pads and the LED emitting essential wavelengths for photosynthesis in plants.

Moreover, thermal simulations indicate that, even with an active heating system, the culture temperature may not exceed 20°C, below the optimal 25-30°C range for algal growth. To address this issue, an alternating operation scheme between illumination and heating is proposed to maintain acceptable thermal and lighting conditions without exceeding power limits. Finally, an assessment of the orbital radiation environment shows that, while occasional bit-flip events cannot be fully ruled out, the expected exposure is not a major risk to hardware functionality and remains within biologically tolerated levels, confirming that any observed variations in algal activity can be attributed to the experimental conditions rather than radiation-induced effects.

While no prototype or biological validation was performed, the work demonstrates feasibility of hosting biological experiments in Pod and provides clear guidelines for further development. Future work should focus on expanding internal capacity, integrating non-invasive diagnostic tools, and optimizing energy management to support longer and more complex missions. Overall, the results contribute to developing compact, low-power biotech systems capable of sustaining and investigating life in space, a key step toward future extraterrestrial research and resource utilization.