Abstract
Sustainable cultivation of nutrient-rich vegetables is crucial for long-term space missions. Leafy greens such as red romaine lettuce and hybrid leafy Asian green are promising candidates due to their compact growth and high nutritional value. However, these crops can accumulate excessive nitrate and iron (Fe), potentially posing health risks in space. Nitrate (NO3−) may convert to carcinogenic nitrosamines when consumed with processed foods under acidic gastric conditions, while excess Fe contributes to oxidative stress and bone loss. Ideal crop characteristics prioritize high potassium, magnesium, and calcium (Ca) concentrations while minimizing Fe accumulation to support astronaut cardiovascular and skeletal health.
This study hypothesizes that elevated light intensity and CO2 enrichment could reduce NO3− accumulation while preserving favorable nutrient profiles. Using NASA's Growing Beyond Earth (GBE) 2023 research protocol, seeds were first exposed to neutron radiation via Californium-252 and then cultivated under controlled LED lighting and elevated CO2 conditions to simulate spaceflight growing environments. Neutron radiation had no statistically significant effect on edible biomass or morphology (p > 0.05). CO2 enrichment significantly reduced NO3− content, partially supporting the hypothesis, but led to nutrient trade-offs, including increased Fe levels and reduced magnesium and Ca. Contrary to expectations, higher light intensity increased nitrate accumulation. A NASA-aligned crop suitability ranking identified low light intensity (230 μmol·m−2·s−1 PPFD) and CO2 enrichment (~1000 ppm) as the optimal conditions for enhancing space crop quality while mitigating dietary risks. These findings may inform NASA's space agriculture strategies for sustainable food production on long-duration missions and offer insights for controlled environment agriculture in resource-limited settings on Earth.