From Farm to Microgravity: a Design for Growing Lettuce in Space

This entry is submitted for the high school category.

This model was primarily based on the four webinars hosted throughout the challenge. In said webinars, the topic of limited and fun astronaut interaction was repeatedly mentioned and encouraged. As well as that, there was also encouragement for the use of a water recycling system built into the enclosed system. Finally, there was the idea that astronauts would not want all of their fresh produce at once. With these thoughts in mind, I had a very interesting time coming up with an efficient solution.

The main structure accommodates two main growing racks (highlighted in green), a space below the growing racks for electronics, water storage, and water recycling, and extra space behind the racks (highlighted in orange) for water and electricity to be hooked up to the lights and racks. The structure is fitted with a clear plastic exterior for enclosing the system and to let astronauts peek in on the plants at will. Airflow will be controlled using 50mm fans at variable speeds to ensure that plants will not dry out or suffocate. These fans will take air from the ISS through the front and pull it through the extra plumbing and wiring space down towards the water recovery system after the air has thoroughly passed through the plants themselves.

The growing racks can provide a medium for nine plants each with a three by three configuration. They can also be easily removed by first detaching water and electricity before sliding the rack out. This is for ease of harvest and offers the ability to test two different growth mediums on a larger scale than the system onboard the ISS. The top rack will have light shone on it from white LEDs connected to the ceiling of the structure. The bottom rack will receive light from white LEDs attached to the bottom of the top rack. Astronauts could also allow only one rack to grow for about fourteen days before letting the other rack start growing. This would ensure astronauts would not have to worry about preserving all of the produce.

For water storage currently, no direct volume is set. This is because I have not prototyped a small scale water recovery solution to see its efficiency. The current water recovery design I had in mind works very much like the current ISS WRS. Air is blown into a centrifugal chamber that is cooled. This chamber moves the water towards the edge where water detectors sense the water and open an electronic valve that allows the water to be pumped back into storage. Based on the end efficiency of the design, astronauts would very rarely have to fill the water tank back up. This allows for even smaller amounts of astronaut interaction.