Growing Beyond Earth Submission

The following is the detailed description of the Growing Beyond Earth submission by Kaylon Paterson. It is being submitted as a professional entry.

The design was created using AutoDesk Inventor 2020 and conceptualized using a combination of systems engineering and aerospace engineering concepts. Red and blue LEDs cover the left and right inner walls, while the areas highlighted in green indicate places where plants will be grown. As instructed:

• The box has dimensions within the 50cm x 50cm x 50cm constraint
• It contains all components needed for successful plant growth including lights, water cycling and ventilation
• It is designed to optimize the number of plants which can be grown within the given parameters

Step 1: Baseplate

The baseplate is made up of three long indentations in which plants can be grown (shown in green with blue plant pillows). These spaces are ideal for plants which need the full 50cm height of the grow box for vertical growth but can also host other plants such as those requiring more horizontal space i.e. lettuce. The six small holes running laterally from one indentation to the next, will allow the passage of tubes between all three chambers. These tubes will be used for irrigation throughout the system. Likewise, the larger vertical holes will allow passage of watering tubes to the vertical pillars discussed in the next step.

Step 2: Vertical Pillars

These vertical planting pillars were selected to optimize the use of space within the box. They allow the user to grow a wider variety of plants in the space as height is no longer restricted compared to designs which use multiple horizontal trays. The plant cups are oriented at a 45 degree angle to avoid overcrowding. With a total of six pillars, each with six planting cups, it is possible to grow 36 plants of varying heights. Coupled with those grown in the baseplate, an estimated 42-45 plants can be grown in one unit simultaneously.

Please note that the size of plant pillows may need to be slightly modified to fit the plant cups.

Step 3: Housing

The housing is comprised of several components and has thus been deconstructed in the following four steps for clarity.

Step 4: Light Grid

Both the left and right inner walls are lined with a grid of red and blue LEDs which produce the optimal wavelengths needed for plant growth. This style of grow light was selected as it has not only been tested thoroughly in the current growth chamber aboard the ISS but is also currently being used terrestrially for optimizing plant growth in indoor farms. This LED grid shall produce 300-400 µmol/M^2/s within PAR (400-700nm) as defined in Plant Growth Optimization by Vegetable Production System in HI-SEAS Analog Habitat (Ehrlich et al.). Additionally, other colors of LED can be added, such as green which has also been proven to have benefits to plant growth, as the grid will be made up of standard 1cm thick LED strips.

Step 5: Lid

The lid of the grow box contains the majority of its technological sophistication. Firstly, the two holes will house ventilation fans for the circulation of air in the box as shown.

The green squares indicate the location of some of the sensory components of the box. These consist of temperature, humidity and CO2 sensors. Understanding that gasses flow differently in free fall, we will place additional sensors along the vertical pillars and baseplate as well. These can include additional thermal, humidity and CO2 sensors, as well as soil moisture sensors within the plant pillows.

Once complete, the ventilation, lights and watering systems will all be automated using a microcontroller platform such as Arduino. The box will thus require very little human interaction as sensors will dictate the response of the system to various changes such as temperature, humidity, soil moisture and gas concentration.

Step 6: Front Panel

The front “doggy door” design was selected to optimize viewing space for astronauts. Based on statements by Dr. Gioia Massa in the article Veggie Plant Growth System Activated on International Space Station, it was determined that making the plants visible could have positive psychological effects on ISS denizens (Herridge). Thus, a sliding glass door will be placed here to allow users to take samples and remove crops without disrupting the system in its entirety, while still being able to view the plants at their convenience.

For larger work such as harvesting and replanting, the entire housing can be detached from the baseplate.

Step 7: Controls

As previously stated, the control of the system will be mediated by a microcontroller such as Arduino. Basic controls such as light cycling, watering schedule and ventilation cycles shall be set via on-board display but can also be made to interface remotely if necessary. Similarly, water and ventilation shall respond to data generated by the various sensors within the box. Additionally, the system shall collect sensory and usage data for future analysis.

Step 8: Irrigation

The grow box will depend on tubing for irrigation as stated previously. Using a series of on-board pumps, as well as capillarity, water will be distributed throughout the various plant growth media (plant pillows). Pumps will be used to maintain water pressure and ensure that water can be distributed on command through the microcontroller interface. These methods of circulation were selected as they are two ideal means of ensuring the flow of fluids in microgravity as stated in Fluid studies on the International Space Station (Motil).

Step 9: Next Steps

Continuing from here, I will begin assembling the microcontroller circuit for the box and upon acceptance into the second round, the box will be assembled and tested using the materials provided.