Many astronauts feel homesick when going to space. The current problem that many researchers tried to resolve is the efficiency of growing plants in space. Plants bring a sense of normalcy to many because it reminds astronauts of their home and fresh ingredients used in their food. Astronauts do not have immediate access to fresh food because their food is packaged from Earth and brought into space. Researchers are trying to find ways of growing plants in space without much intervention and dependency. It is important to consider microgravity, light, temperature, and reservoir in these designs in order to maximize space and produce an abundance of plants with little maintenance.

We have sketched a design that will fill these requirements and be easy to maintain. This design compacts up to 16 plants with much-needed space and takes into consideration the plants’ needs through the use of a ventilation system, LED lights, a polyethylene inspired water tank, and coir (growth medium).

After thinking of a series of ways to devise a plan for our growth chamber it became increasingly clear that limiting our plan to a cube was restricting. Naturally, we thought of different shapes that we could use to optimize growth in the chamber and oddly enough, thought of an octagonal chandelier. Being that it could be a prism that could suit the 50x50cm3 criteria it seemed apparent that we go with it and add layers. So, our chamber is able to hold 16 plants oppose to the standard 6, used on the International Space Station today

Supplies

Mini polyethylene tank replica (plastic with pressure system)

Ventilation unit placed in the cube

Growth medium: coir

LED strip lights (about a 5:1 ratio of red to blue lights)

Octagonal frame; no faces, only sides creating an octagon shape (made of metal)

Temperature and humidity sensor (placed on the polyethylene tank)

Tubes running from the polyethylene tank to the plants

Outer layer stainless steel

Step 1: Framework

Our design is going to use a cube as the outer frame but inside the cube (where the octagonal prism is located) would be where the plants are placed. This helps optimize space and maximizes plant growth. By introducing two shapes helps concentrate the plant production in one area with a lot of room for the plants to grow. The materials used for aiding plant production will be placed inside the cube (but not inside the octagonal prism).

Step 2: Assembling the Inner Layer (octagonal Prism)

The inner layer of the octagonal prism contains 2 plant shelves, 1 shelf divided into 8 parts so 8 plants will be able to grow on this one shelf. The second shelf adds another 8 plants making a total of 16 red romaine lettuce. This design gives space for multiple plants to grow. However, the octagonal prism’s sides are made up of metal frames that do not have the faces. This helps the astronauts to take out the octagonal prism from the cube and take out the plants from the 2 shelves.

At the center of the prism is where the reservoir will be. The reservoir is a motorized polyethylene inspired tank replica. The tank can be opened at the top for it to be refilled and water is given to each plant through a pressurized water system connected to tubes. The reservoir also has a timer that can be set beforehand for the plants to be watered a certain amount of water at a specific time. The pressure system combats against the microgravity and is controlled by how much pressure is necessary to provide an adequate amount of water to each of the plants.
Because the second shelf would not be able to obtain the maximum amount of light since the first shelf is blocking it, we proposed to put another set of LED strip lights along the edges of the bottom of the first shelf. This will help the plants in the second shelf grow just like the first shelf, to their maximum height. The growth medium being used is coir which is the fiber from coconut. This growth medium has numerous benefits including improving air porosity of soils, even when wet, and helps in retaining moisture. It can also be re-wet when dried which can significantly increase the amount of nutrition in the red romaine lettuce.

The octagonal prism is only going to be in its skeletal layer. There are no faces on any sides of the prism except for the bottom/base. The frame of the octagon can be made out of either metal or plastic that aren’t the best conductors of heat so the astronauts don’t burn their hands when they take the garden out. The cube will have an opening at the top and the garden can be slid out from the top using some sort of rails. The idea of having rails was inspired by my dresser. The drawers on a dresser are pulled out using wheels and for our design, we plan to do something similar except the rails are vertical. The plants on the first shelf can be taken out simply by opening the top of the cube. To take the plants out from the second shelf, you would need to slide out the garden from the top. The astronauts can put their hands through since there are no faces on the sides and get the vegetation out. Since there is microgravity, pulling the garden up won’t be a problem.

Step 3: The Cube

The cube will be made out of stainless steel metal. With regards to our method of circulating oxygen throughout the growth chamber, we propose a ventilation unit installed inside of a bi-layer wall of the cube. The ventilation unit will replicate a central cooling and heating system, that will allow the astronauts to adjust the temperature in conjunction with the plant’s growth. It's commonly known that there are some issues with minor temperature adjustments on the International Space Station, so our system aims to assist in creating the perfect habitat for the plants.