Providing photons for food in regenerative life support: A comparative analysis of solar fiber optic and electric light systems

Providing photons for food production in a plant-based bioregenerative life support system (BLSS) is a significant component of total system cost. The energy to drive photosynthesis is the dominant factor in system net mass, power, and cooling requirements. These requirements have been historically converted to an Equivalent System Mass (ESM) to facilitate a trade studies among technology options. Previous trade studies were conducted more than 10 years ago and did not include advances in solar photovoltaics and light emitting diode technologies.
We evaluated electric, solar fiber optic (SFO), and hybrid-based lighting systems for Lunar and Martian missions. The Electric to SFO ESM ratio is 1.09 for the Lunar base and 0.68 for the Martian base. This indicates that providing lighting from SFO has a slightly lower system mass on the Moon, and a 47% greater mass on Mars. A sensitivity analysis indicated that ESM ratios are sensitive to 1) the LED electric lighting efficiency and 2) length of the fiber optic cables. Other assumptions had smaller effects on the ESM ratios. Qualitative parameters important to system design are discussed for each mission and lighting system. Although the focus of this work is lighting supplied to plants, this can be applied to multi-purpose lighting in a spacecraft or habitat.