Aeroponics Science Report
There is a need to develop sustainable methods for providing oxygen to crews and the removal of carbon dioxide from the interior atmosphere. Since the space race began, space exploration has relied on life support system technologies from the 50’s and 60’s. The ISS still relies on oxygen from pressurized tanks launched up from Earth. We have not been able to sustain a closed loop life support system in space. For a long-duration mission, for example going to Mars, new breakthroughs must be achieved in life support systems, primarily environmental control. Oxygen production and carbon dioxide reduction is a crucial step in creating a livable atmosphere. On Earth, terrestrial plants and algae control the environment. The same can be done in space. The goal is to design and fabricate a bioregeneration system that uses a technique called aeroponics and then collect data on oxygen production, carbon dioxide reduction, and food production. Along with this the system should be automated with little interference by the researcher/astronaut.
The aeroponic system should be as flight ready as possible without geometry considerations. Seeing that launch vehicles and habitats have varying dimensions, a box shaped structure will suffice for now. The tank and lower structure is composed vacuum bagged carbon fiber. The tank has also been coated in a quick setting polyuria coating. This coating is Federal Drug Administration (FDA) approved for tanks with potable water and corrosive chemicals. Along the side of the lower structure are housed the electronics, fluid dispensers, and power supply. The upper structure (grow chamber) is composed of a clear polycarbonate box structure. On one side of the structure, a fan has been mounted for aeration. The top of the structure holds the LED grow lights.
In terms of sensors, the system must be able to automate the various fluids required for an aeroponic system. A pH sensor and dissolved oxygen sensor are used inside of the tank for water regulation. The research aspect of this requires sensors to monitor the respiration of the plants in the grow chamber. Oxygen and carbon dioxide sensors are also being used in this section.
With regard to hardware, to deliver the fluids, automated syringes will be used. However, automated syringes are expensive on the market, thus custom ones have been fabricated. The structure for this device was 3D printed and is controlled by a microcontroller. The LED grow lights were purchased with the specific spectrum of light for the plants being grown. The fan is a simple efficient computer fan with a calculated flow rate. Aeroponic systems rely on atomization of water particles in the tank for the roots to take up nutrients while also being in the air. A small high-pressure pump with a spray head is used in order to do this.
Finally, in terms of electronics, the system runs on an Arduino microcontroller based system. All of the sensors and fluid dispensers interact with one another to control the environment. Data from the gas sensors will be collected and saved on a SD card. Later on in the future, the grow lights will have the capability of being turned on and off by the microcontroller. Sensor data will also be read out to LCD screens in the lower section for easy data viewing.
When complete the system will be able to find the oxygen production and carbon dioxide reduction of the plants within the system and food production. For now the system has been designed around spinach and strawberries. This is because of their small growth footprint. Along with this, future research can be done with light fluctuation and plant growth.
Currently, this study incorporates Golden Pothos plants as they are more resilient, and more likely to survive the trip to the MDRS. The plant used in the aeroponic system will be compared to a control in soil, which will be located in the same environment (the Hab). Prior to the beginning of the study, the amount of roots and their lengths were measured. The roots will again be counted and measured at the end of our stay at the Hab. The purpose of collecting measurements prior to the beginning and at the end of the session is to maximize the plant’s survival (i.e. we do not want to consistently remove them from the pot and/ or the aeroponic device). During transit to the MDRS, the aeroponic system was slightly damaged, but was easily repaired onsite.