To investigate techniques that can be scaled for crop production in microgravity, a NASA-sponsored Sierra Space team is developing soilless nutrient delivery and recovery technologies that will be demonstrated via plant tests aboard the International Space Station.
In the future, plants may play a significant role in long-duration life support in space by providing food, producing oxygen, removing carbon dioxide, and purifying water. In the near term, plants will provide a means to supplement crew diet through the production of salad crops as a source of fresh food. For example, Sierra Space is developing the Astro Garden large-scale vegetable production system as a concept to produce sufficient garden vegetables for a crew of four. The eXposed Root On-Orbit Test System (XROOTS) investigation is designed to test critical aspects of the Astro Garden system by using hydroponic and aeroponic techniques to grow crop plants without soil, making large scale plant production in space feasible.
The objective of the XROOTS Technology Demonstration is to evaluate soilless nutrient delivery and recovery techniques over the course of plant growth in the microgravity environment of the space station. XROOTS will be integrated with one of the Veggie plant growth units currently being used aboard the space station. Following launch, the base plate and bellows will be removed from the Veggie Facility and the XROOTS module will be mounted below Veggie, and data and power connections established. Veggie will provide lighting and air exchange between the Veggie growing volume containing XROOTS and the space station cabin. After a thorough checkout of the XROOTS system, seed cartridges will be placed in the XROOTS chambers, the nutrient solution will be mixed and placed in the XROOTS reservoir, and the XROOTS module will be powered up and initiated to begin testing.
Operations are planned to occur over the course of six months, with individual tests lasting between 14 and 60 days. XROOTS is designed to observe variables such as nutrient solution spray, flow, and ebb behavior in different capillary configurations and with different operating protocols. XROOTS uses still images and video to observe root development and the interaction of fluid with roots at different growth stages. Data will also be collected using sensors and short periods of crew observation. The XROOTS payload will support testing of two root module configurations, three root/shoot interface designs, and multiple operating protocols (for fluid delivery and recovery). Tests will be conducted with multiple crop species, some through the germination stage and others to full harvest stage.
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