Plant Growth Chamber

Improvements and new models are needed for the current system for plant growth on the ISS, called Veggie [1][2][3]. Our design utilizes many features that the Veggie system already uses: the air circulation system which uses carbon dioxide from the cabin and fans to circulate the air in microgravity, the LED’s that are spread throughout the plant growth chamber, and the water reservoir which holds and distributes water from the space craft [4]. Our design features a cylindrical tube placed in the middle of the cube where plants will be able to grow radially outward towards the LED’s. Wicks held in the central tube will provide water to the plants from the reservoir. This supplies the plants with all the necessary conditions for growth: water, carbon dioxide and light.

Frame: A lightweight material such as aluminum

Lighting: RGB LEDs

Water: Plastic box for reservoir, wicks

Air Circulation: Small fan

Central Tube: A lightweight material such as aluminum

The frame is able to connect all the different parts. It allows for stability with openings for easy usability. Maintenance on other components, viewing, and plant harvesting are possible due to the frame design.

The frame is a 50 cm cube with openings on four sides The frame has a thickness of 1 cm and the openings are 30 cm squares.

When made from aluminum, the frame weighs around 30.5 kg [5][6].

The LED’s are focused on the four vertical corners of the frame (perpendicular to the sides of the frame with no opening). Given that the plants will grow towards the light, placement is crucial. The LEDs will be placed in line with the plant openings. Using this design, the plans will have the maximum distance to grow since they will extend towards the diagonals.

The four LED panels are approximately 12 cm wide at the base and 48 cm tall. They are also 1 cm thick.

Each LED panel weighs approximately .5 kg, with all four panels weighing 2 kg [7].

The water will be held in two reservoirs, one on the top of the frame and one on the bottom of the frame. This ensures that water will be delivered evenly to all the seeds/plants within the inner tube. Two sources of water will also put less stress on the wicks as they will not have to deliver water to the full length of the cylindrical tube.

The wicks will transport nutrient rich water to the dirt that is held within the cylindrical tube. Due to the presence of microgravity, capillary action will be solely responsible for the movement of water. The roots of the plants will grow towards the water source so the wicks need to be sufficient in length to ensure that water reaches the roots.

The water reservoirs are 20 cm squares with thickness of 1 cm and are made of polycarbonate.

The wicks are wick cord.

Each reservoir weighs approximately .04 kg when empty and .44 kg when full. Together, the two reservoirs weigh .8 kg when empty and .88 kg when full [8].

Together, the wicks weigh approximately .1 kg.

Under the conditions of microgravity, there is no air circulation. Fans are needed in order to create movement of carbon dioxide and oxygen. Two fans will be place on opposite sides of the frame (mirroring each other) in order to allow for optimal air circulation. This will ensure that there are no air pockets within the larger design, meaning the plants will remain healthy.

The fans are 2 TriPole Mini Handheld Fans.

Each fan weight .1 kg, together the fans weigh .2 kg.

The central tube is centered in the cube and reaches from the lower reservoir to the top reservoir. It is filled with nutrient rich dirt and contains the wicks from the water reservoir. It holds the seeds and plants, acting as a large plant pillow. It is able to be disconnected if repairs are needed or if the dirt needs to be changed. The outer shell for the cylindrical tube will have small openings that can be removed at the source for each plant. These will be able to be removed to initially place the seed and finally to remove the roots and head of the plant. This resolves the issue of constantly needing to empty and refill the tube in order to plant the seeds and remove the roots.

The central tube has an outer radius of 5 cm (diameter of 10 cm) with a thickness of approximately 1 cm. The tube is 46 cm tall, allowing for 4 holes on each side (16 holes total) for plants to grow out of. The holes are separated vertically by approximately 8 cm from each other (center to center). The 16 holes have radii of 1 cm (diameter of 2 cm).

The soil will be traditional dirt with arcillite added in for nutrients and aid in growth. The seeds are outredgeous red romaine lettuce and grow upwards of 15 cm long with a full growth in 28 days.

When made from aluminum, the central tube weighs approximately 3.5 kg [5][6].

The soil held within the tube weighs approximately 2 kg.

The process taught us about plant growth and how the conditions of space affect their growth. We also learned about the importance of efficient use of space due to the confines of space within the cube. It is also very important to consider all necessary equipment needed for successful plant growth. Simply through the rearrangement of materials and tools, one can create a more efficient overall system.

This design and others similar to it are important in furthering humanity. If we seek to explore outside of our world, we will need to figure out how to keep ourselves alive outside of our world. An extremely important aspect of this is food, which this plant growth chamber is focused around [9]. Not only do we need to learn how to grow food in space, but how to do so in an efficient manner.

[1] P. Blau, “Veggie,” Spaceflight101 International Space Station. [Online]. Available: http://spaceflight101.com/iss/veggie/. [Accessed: 02-Dec-2019].

[2] “Experiment Details,” NASA. [Online]. Available: https://www.nasa.gov/mission_pages/station/resear... [Accessed: 02-Dec-2019].

[3] L. Herridge, “Veggie Activated to Grow Fresh Plants on Space Station,” NASA, 02-Mar-2015. [Online]. Available: https://www.nasa.gov/content/veggie-plant-growth-... [Accessed: 02-Dec-2019].

[4] “Experiment Details,” NASA. [Online]. Available: https://www.nasa.gov/content/veggie-plant-growth-... [Accessed: 02-Dec-2019].

[5] “Aluminum volume to weight conversion,” Aluminum volume to weight conversion. [Online]. Available: https://www.nasa.gov/content/veggie-plant-growth-... [Accessed: 02-Dec-2019].

[6] Mass, Weight, Density or Specific Gravity of Different Metals. [Online]. Available: https://www.nasa.gov/content/veggie-plant-growth-... [Accessed: 02-Dec-2019].

[7] “Led panel light 30 x 120 cm - 40 w, neutral white,” Velleman Spotlight. [Online]. Available: https://www.nasa.gov/content/veggie-plant-growth-... [Accessed: 02-Dec-2019].

[8] “Guide to Plastic Weights,” Find Out How Much Each Type of Plastic Weighs. [Online]. Available: https://www.nasa.gov/content/veggie-plant-growth-... [Accessed: 02-Dec-2019].

[9] “Growing Beyond Earth Maker Contest,” Fairchild Tropical Botanic Garden. [Online]. Available: https://www.nasa.gov/content/veggie-plant-growth-... [Accessed: 02-Dec-2019].