By Morgan Mcallister, NASA
The Advanced Plant Habitat (APH), a recent addition to the International Space Station, is the largest growth chamber aboard the orbiting laboratory. Roughly the size of a mini-fridge, the habitat is designed to test which growth conditions plants prefer in space and provides specimens a larger root and shoot area. This space in turn will allow a wider variety of crops to grow aboard the station. Thus far, the habitat has been used to grow and study Arabidopsis, small flowering plants related to cabbage and mustard, and Dwarf Wheat.
Its monitoring and environmental control systems regulate temperature, oxygen, and carbon dioxide levels, and the system settings can be adjusted for growing different types of plants. Although the system is largely autonomous, the crew adds water to the chamber and changes atmospheric elements such as an ethylene scrubber, carbon dioxide scrubber & bottles, and filters. All systems can be monitored and controlled from a computer on the ground that interfaces directly with the habitat to relay instructions and detailed adjustments to ensure investigation integrity.
Because gravity is a constant downward force on Earth, researchers take advantage of the microgravity environment of the space station to achieve a clearer perspective of plant growth habits. Gravity is one of the major cues plants use to guide their growth, but microgravity can act as a kind of mute button that suppresses the role of gravity, enabling researchers to see what other cues take charge.