A Low Earth Orbit CubeSat for tomato ideotype cultivation

The autonomous production of nutrients and oxygen in space is a challenge for future human space exploration. In every mission scenario, a significant cost- and mass-saving issue is represented by recycling resources, plants could easily take charge of this process. By photosynthesis, plants can absorb carbon dioxide and consume crew waste to generate oxygen, fresh nutrients and clean water. However, no plants were adapted to space environment and no specific ideotype exists. Stresses induced by microgravity, magnetic fields, radiations, artificial illumination and altered atmosphere can affect plants performances. Moreover, an ideal plant for space missions must also produce useful molecules other than common nutrients (antioxidants, antibacterial etc…). MicroTom is a tomato cultivar that could be a good choice for space missions because of its characteristics: small size (~0.0156 m3), short life cycle (70-90 days), high photosynthetic efficiency and productivity (20-30 fruits/plant; 2-5 gr/fruit), continuous flowering, high density cultivation, good performances in soilless cultivation. This cultivar has been engineered to enhance anthocyanin content in whole plant, through the ectopic expression of a transcription factor. In fact, it is generally assumed that anthocyanins are a powerful antioxidant molecule able to protect plants from Reactive Oxygen Species induced by abiotic stresses such as those induced by LEO (Low Earth Orbit) conditions. A 12-Unit CubeSat mission has been conceived by a research team from both Sapienza - University of Rome and ENEA (Italian National Agency for New Technologies, Energy and Sustainable Economic Development) for supporting the MicroTom cultivation in space, attempting a complete seed-to-seed life cycle. The spacecraft will consist of an autonomous biological unit, with a dedicated Environmental Control and Life Support System. During the mission, life parameters will be controlled and fine-tuned to improve yield and quality of production. To verify plant health status during the mission, the on-board instrumentation will be devised to control temperature, relative humidity, air pressure and gas composition, pH and electric conductivity of nutrient solution, Photosynthetically Active Radiation, Normalized difference vegetation index and radiation dose. Finally, plant growth and health will be monitored by on-board cameras. The mission could represent the first example of plant growing in an unmanned spacecraft. In the present paper Micro-Tom characteristics, design of the 12-U CubeSat and expected plant performances, as well as possible benefits for human health during future interplanetary missions, will be discussed.