The future of human exploration on the Moon depends largely on our ability to sustain astronauts with limited resources. A recent study published in Acta Astronautica has delved into one promising solution: the use of lunar photobioreactors (PBRs) to produce oxygen and food directly on the Moon. This approach seeks to reduce the need for costly supplies shipped from Earth. The research, led by a team from the Technical University of Munich, builds on earlier concepts that explored the potential of in-situ resource utilization (ISRU). They propose that algae-based PBRs could meet the essential needs of oxygen production and nutrition while significantly lowering mission costs. This study not only contributes to the growing body of knowledge on sustainable space exploration but also highlights the role of lunar resources in supporting future lunar colonies.
What Are Photobioreactors and How Could They Help on the Moon?
Photobioreactors are designed to harness the natural process of photosynthesis to generate useful products such as oxygen and biomass. In a PBR system, algae or other microorganisms absorb carbon dioxide (CO2) and water and, through photosynthesis, release oxygen while also producing organic material that can be used as food or converted into biofuel. This biological approach could play a crucial role in providing vital resources to astronauts on long-term lunar missions. The key challenge of using PBRs on the Moon, however, lies in the harsh lunar environment.
Unlike Earth, the Moon lacks an atmosphere, which means that any PBR system would need to be carefully enclosed to protect the organisms inside from extreme radiation and vacuum conditions. Direct sunlight would also pose a threat, as the intense solar radiation could quickly kill the algae and destroy the system. Researchers propose various design solutions to protect the PBRs from these elements, including specialized lunar-built shelters and transparent enclosures that could allow sunlight to reach the algae without exposing them to harmful radiation.
Harnessing Lunar Resources for Cost-Effective PBRs
One of the significant advantages of using PBRs on the Moon is the potential for cost savings. Transporting materials from Earth to the Moon is notoriously expensive, with launch costs estimated at $100,000 per kilogram. The Technical University of Munich team focused on utilizing local lunar resources to build the PBRs, which could result in significant savings, possibly in the range of millions of dollars per system. Specifically, the study compares two types of PBR designs: tubular airlift and flat panel airlift (FPA) systems.
The FPA design, while more efficient, requires more maintenance than the tubular counterpart. However, both designs offer a significant reduction in cost compared to transporting pre-built systems from Earth. The team estimates that the tubular design could save up to $50 million when constructed using materials derived from lunar regolith, which is rich in metals and minerals.
Although lunar regolith provides many of the materials required for the reactor’s structural components, challenges remain in producing essential items like clear glass for light transmission. To date, no one has successfully made clear glass from lunar resources, though research into this area is ongoing. The alternative—relying on Earth-based LEDs for internal lighting—is energy-intensive and would require advanced technology that might be difficult to produce locally. Despite these hurdles, the possibility of using lunar resources to create efficient PBR systems remains a promising avenue for future research.
The Role of Algae and Other Biological Considerations
The effectiveness of lunar PBRs largely depends on the health of the algae inside the system. Algae require nutrients such as phosphorus, nitrogen, and chlorine to thrive, but these elements are in short supply on the Moon. The researchers suggest that astronaut waste water could be recycled to provide these vital nutrients, helping to “close the loop” on resource use in a lunar environment. This recycling process would reduce waste while supporting the biological systems that are critical for food and oxygen production.
Another challenge in this biological system is the availability of carbon, which is essential not only for algae growth but also for plastic production. Carbon is relatively rare on the Moon, making it difficult to rely solely on lunar resources to produce the necessary materials for constructing and maintaining PBRs. This scarcity of essential elements means that some supplies, like plastics and certain chemicals, will still need to be brought from Earth. The research team emphasizes that a hybrid approach, combining PBRs with more traditional ISRU methods such as Molten Regolith Electrolysis for oxygen production, could be the most effective solution.
Source link
