CO2–Recycling for Future Exploration Missions



Journal Title

Journal ISSN

Volume Title


49th International Conference on Environmental Systems


For future long-duration human exploration missions to far distant destinations, e.g. extensive surface missions to Moon, journeys to Mars and beyond, efficient recycling technologies to handle consumables and waste are required. A pronounced potential for closing the material loops in life support systems (LSS) lies in the processing of the metabolic waste product carbon dioxide (CO2). After concentration by adsorption, either the Sabatier-, the Bosch-process or Solid Oxide Electrolysis (SOEC) can reduce CO2 in a physico-chemical (p/c) way to regenerate oxygen (O2), however leaving the carbon portion unused. The next logical technological step to recycle CO2 are therefore biological systems. Based on photosynthesis, plants or algae may generate edible biomass from CO2 and release O2. Especially systems based on microalgae are favorable for space missions due to their faster growth rates, higher harvesting index and advanced light exploitation compared to higher plants. Hybrid systems combining p/c and biological technologies could be an intermediate step and increase system redundancy. This paper explains the importance of CO2 recycling for future exploration mission and presents relevant bio-technological approaches. The results of various system studies on different LSS configurations (p/c, hybrid, biological) in terms of air revitalization are presented. The seizing of the biological components uses experimental data gained from the cultivation experience of the microalgae species Chlorella vulgaris in microgravity (µg) adapted photobioreactors during ground testing at the University of Stuttgart over the last 10 years.


Jochen Keppler, University of Stuttgart, Germany
Stefanos Fasoulas, University of Stuttgart, Germany
ICES501: Life Support Systems Engineering and Analysis
The 49th International Conference on Environmental Systems as held in Boston, Massachusetts, USA on 07 July 2019 through 11 July 2019.


CO2, Life Support System, Air Revitalization, Microalgae, Photobioreactor