Introduction: 'Outredgeous' Red Romaine Lettuce Growth Chamber

About: I am a college student at the University of Southern California studying Mechanical Engineering.

This Instuctable is a submission for the Collegiate Division of the Growing Beyond Earth Maker Contest.

As human endeavours in space become increasingly complex, it is no wonder that scientists and engineers have begun to develop systems for growing and harvesting edible food sources in outerspace. In the future it will be much more efficient for astronauts to produce the majority of their edible commodities among the stars instead of having them delivered from Earth--especially in the context of long-term space voyages.

My proposed design for the Growing Beyond Earth contest looks to improve upon the current Vegetable Production System aboard the International Space Station by providing more surface area for the growth of 'Outredgeous' red romaine lettuce. I also paid particular attention to the maintenance of the grow chamber and sought to make it easier for NASA scientists to operate and engage with the grow chamber.

Step 1: Design of Grow Arrays

In this design, ‘Outredgeous’ red romaine lettuce plants are grown in grow pillows fastened to growing arrays. The growth chamber contains four grow arrays with six holes each, allowing for a maximum of 24 mature lettuce plants to be grown at a time. Each grow array was designed to be concave and has the ability to fit seamlessly against other grow arrays within the grow chamber. The resulting configuration of the four grow arrays within the grow chamber creates a spacious bubble for the lettuce to grow in.

Grow pillows are fastened to the grow arrays using taunt silicon tubing. The flexibility of silicone tubing will ensure that the grow pillows remain in place while in the grow chamber, but also provides scientists ease of maintenance when replacing them. Furthermore, each of the grow pillows is watered via a watering tube that enters the grow array through a horizontal slit that interfaces with the system base. Each of the grow arrays are fastened to the system base with threaded screws.

Step 2: Design of System Base

The system base was designed with the intent of placing the watering system, air circulation system, and lighting system together in a single location so that the majority of the grow chamber’s maintenance could be performed easily. All electrical elements exist within the system base. The system base contains mounts for the LED lighting array and air circulating fans which project into the center of the grow chamber.

Step 3: Integration of Watering System, Air Circulation System, and Lighting Element Into the System Base

The watering system consists of four refillable water storage bags, each of which are attached to six peristaltic pumps (Shown in blue in the above photos). Peristaltic pumping is an effective method of water transport that does not rely on gravity for the water to flow. The pumps are connected to tubing which connects to each of the grow pillows. Each peristaltic pump can be controlled to ensure that the plant pillows are receiving the necessary amount of water daily. The refillable storage bags can be refilled through the system base.

The air circulation system consists of four fans attached to the system base (shown in black above). The four fans are small enough that they do not obstruct the growing volume. Each of the fans can be controlled to vary the speed of the air flow. Each of the fans positioning can be manually adjusted during maintenance by rotating the fan itself. The electrical components for the fans are stored within the system base.

The lighting system consists of a cylindrical LED array of red, blue, and green LEDs (shown in pink above). The array is attached to the center of the system base and occupies the centermost region of the grow chamber: this way, the lettuce plants growing on the four grow arrays surrounding the LED array can grow directly towards it. As plants grow towards the LED array the brightness can be adjusted to ensure the plants are receiving the appropriate amount of light energy.

***Electronic connections and water piping were not modelled. A black box has been included in the system base to represent electrical components stored within the system base.

Step 4: Enclosure of System Within 50cm X 50cm X 50cm Insulating Container

Attach each of the grow arrays to the system base with threaded screw fasteners. Then the system base is placed within the insulating container and secured to it with another set of threaded screw fasteners. The insulating container provides the grow chamber an added level of rigidity/structure, and makes the grow chamber a grow chamber by trapping heat and moisture. Each side of the insulating container can be accessed through a hatch door. Each of these doors are made out of clear acrylic, except for that on the system base which is made out of a darker ABS plastic.

Step 5: Installation of Plant Pillows and Continued Maintenance

Upon the complete assembly of the grow chamber the plant pillows can be installed. Plant pillows are first secured to the grow arrays, and then water lines from the system base are drawn up through the horizontal slit and attached to each of the grow pillows. From that point on, all systems are a go! With the appropriate amounts of water, light, and air circulation the ‘Outredgeous’ red romaine lettuce will thrive within the concave growing volume provided by my design for a re-designed growing chamber.

Thank you for taking the time to read through my design!

Growing Beyond Earth Maker Contest

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Growing Beyond Earth Maker Contest