Introduction: The Most Awesome Space Botany Instructables Ever Issue 01: Amazing Misters
Astronauts on the ISS eat a varied diet, but miss the crunch of fresh vegetables. Lettuce is the crop chosen to fill this need, but it's a challenge to grow lettuce in a space-efficient way on the station. This Instructable endeavors to use aeroponics to create a modular growth environment that maximizes a tiny footprint. We are entering our design in the professional category of the Growing Beyond Earth Maker Challenge.
This design highlights 3 concepts: aeroponic growing conditions, flexible positioning of the cup shelves, and maximal customization of the growing conditions for each plant.
In addition to needing more efficient space usage, one of the current challenges to growing vegetables on the ISS is the transport of heavy growing media, which has to be discarded after use. Aeroponic growing has the potential to alleviate this problem as the container and misters can be reused. In our design, water and nutrients are delivered to the roots of each plant using a piezoelectric mister.
The design holds a maximum of 36 plants, each in its own set of two cups. Thirty-six opaque cups (silver, in the photo) are placed in holes in the three shelves, 12 cups to a shelf. One individual transparent mister cup is then placed inside each of the 36 opaque holders. This design shields the roots from light, but also allows them to be monitored, if needed, by simply removing the inner mister cup unit. The distance between the shelves can be varied, which could be useful if staggering planting dates.
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Step 1: Preparing to Build the Grow Cube Frame
Since we had two design options we wanted to explore, we wanted a frame for our grow cube that would allow for easy reconfiguration. Our design was inspired in part by erector sets and in part by the threaded rods that allowed for adjustments on one of the maker-space 3D printers. The frame can be easily taken apart or folded up when not in use. The steel bars have lots of pre-formed holes for attaching various components, and the wing nut shelf brackets can be adjusted to change the height of interior shelves as plants grow.
We tentatively plan to cover the frame with white woven polypropylene on the sides and aluminum foil on the top and bottom. We chose foil for the top because we thought having a non-flammable material next to our homemade lights was the wisest course of action. On the bottom, foil serves to both reflect light and protect our counter from any leaks. The woven poly on the sides provides water and humidity containment while still allowing for air infiltration and is a light-reflecting white (on the interior).
- Two (1 ⅜”) x (48”) Zinc-Plated Punched Steel Bars
- Two (1 ½”) x 14-Gauge x 36” Zinc-Plated Slotted Angle
- Four (3/8”) x (24”) Zinc-Plated Threaded Rod
- Sixteen ⅜” nuts
- Twelve ⅜” wing nuts
- Twelve ⅜ inch washers
- Hot glue (or epoxy)
- Powered cut-off saw, rotary cutter, or manual hack saw
- Bench grinder or file
- Measuring tape
- Two 9/16” box wrenches, or adjustable wrenches
1. Cut two 50 cm (19.7”) long pieces from each flat steel bar (4 total) and L steel bar (4 total). Cut one 50 cm (19.7”) long piece from each threaded rod (4 total). We used a powered cut-off saw for this, but many cutting options would work.
2. Grind or file all cut edges to remove metal burrs and rough spots. This step is especially important for the threaded rods, to ensure that the nuts will screw smoothly onto them.
3. Secure washers to wing nuts with hot glue. For longer term durability, you could glue with epoxy instead. We will likely do that if our design is accepted. Make sure you glue them so that the hole on the wing nut is unobstructed. These will be the adjustable supports for the shelves.
4. Screw three wing-nut supports onto each threaded rod. Exact spacing is not important at this time, but they need to be far enough away from the ends of the rods to attach the rest of the hardware. They can be adjusted as needed to support the cup shelves later.
Step 2: Assembling the Grow Cube Frame
1. Form a square with two flat bars forming two parallel sides and, perpendicular to those, the two L-brackets forming the other two parallel sides. The flat bars should be installed outside of the L-brackets for simplicity of construction. See upper left picture.
2. Build the frame corners. Screw a nut down a few cm on the end of each threaded rod then put the rod through each corner where the bars and brackets overlap. Put another nut on top of the threaded rod to hold the bars in place. Tighten both nuts against the flat bars until secure, snugging the nuts so that the frame is square and the outer nut is within a few mm of the end of the rod. See upper center picture.
3. Repeat, forming a square and securing it to the threaded-rods for the other side of the cube.
Step 3: Covering the Frame
- Woven polypropylene - We scavenged ours from three 50 lb chicken feed bags. Each bag provides a piece of material that is roughly 81 x 74 cm (32 x 29”). You could also use a white woven poly tarp.
- Aluminum foil - wide roll, heavy duty recommended
- Masking tape (optional)
- Adhesive hook-and-loop (Velcro)
Cover the frame with your selected materials using the below illustration as a guideline. Blue boxes indicate where holes should be cut. Fan holes should just fit the size of the fans and be sealed to the fans with tape or hook-and-loop. Intake holes should be slightly larger than the fans. The aluminum foil can be secured in place with tape, and the woven poly can be secured with strips of hook-and-loop (Velcro) attaching the seams to allow for easy removal.
Step 4: Preparing to Build the Mister Cups
Our modular nested cup design allows individual plants to be added or removed as needed (e.g. disease, poor growth, replanting). The clear internal grow cup described in this section would be placed inside an opaque outer cup to provide dark conditions for root growth. Water is delivered to the plants by aeroponic misting, which should result in a very efficient use of water. Nutrients will also be delivered in the mist, so a physical growing medium is not needed. Note: for proof of concept, we have successfully grown lettuce aeroponically, using a large 5-gal bucket design. The plants continued to grow well 2-3 weeks past the 28 day experimental period. However, these plants were started in a conventional medium, then transferred to the aeroponic setup in a few weeks. More recently, we sprouted seeds using the mister cups, and are continuing to monitor their growth.
Since we have unanswered questions about how ultrasonic misting would work in space, we propose 2 options below, each of which could work with the grow cups described here.
- Two 9 oz plastic cups (use flexible disposable cups (usually #6 polystyrene), such as those pictured, rather than brittle cups )
- One lid for the 9 oz cup
- One 2” (5 cm) net pot + foam insert (any hydroponics supplier should sell these)
- One kitchen sponge (scrubber side will be removed, so fine to use sponge without it)
- Two pieces of wool felt, approx 2.5 cm x 5 cm (1” x 2”), the bottom half tapered (only needed if the cup is to be used for growing from seed)
- One 113kHz ultrasonic mister with a control board (a search for “113kHz ultrasonic mister” will give you several suppliers. A few notes: misters operate at frequencies other than 113kHz. Other frequencies may work here, but we’ve only tried 113kHz. Purchase the mister with control board. You will not need a control board for each mister cup you make, but we are still working to determine how many misters you can operate with one control board.)
- One ½ ” Schedule-40 D-2466 pvc elbow fitting (for alternate Vertical Mister arrangement)
Step 5: Horizontal Mister System: Cutting the Net Pot
Cut out the center disk in the bottom net pot.
Step 6: Horizontal Mister System: Assembling the Inner Pot
1. The foam net pot inserts usually come with 2 pre-cut slits which intersect at the center of the insert. (If not, cut a 3.75 cm (1.5”) slit through the center of the foam, then a second 2.5cm (1”) slit at 90 degrees to the first.) The point where the 2 slits intersect at the center of the foam disk should then be notched away to create a space for the plant stem to pass through. Roots will eventually grow below the foam disk, while the leafy portion of the plant will grow above it.
2. Cut a 2.5 cm x 5 cm (1” x 2”) piece of wool felt. Then, about halfway down the longer side, taper the felt as above. The exact dimensions are not critical. Repeat for the second piece of felt.
3. Insert the 2 pieces of wool felt into the long slit of the foam, tapered end facing down, with approx 1 cm (0.4”) of wool extending up above the top of the foam.
4. Then, insert the foam disk into the top of the net pot (which has had the center disk removed, as shown in step 1, above). The wool felt should be at least 1 cm (0.4”) ( from the bottom of the net pot, so it will not block the mister. [Your felt might not extend down as far into the pot as in the image. This is fine.]
5. Sprinkle a few seeds between the two pieces of wool felt.
Step 7: Horizontal Mister System: Making the Water Reservoir
1. Cut a circular piece of sponge to fit in the bottom of the plastic cup.
2. If your sponge has a scrubber side, remove it. (Tugging at it + scissor snips should do the job.) Place the sponge circle in the cup, with the now more-or-less removed scrubber side facing down.
3. Add water to the cup. Sponge should be saturated, but not submerged.
Step 8: Horizontal Mister System: Modifying the Mister
1. Remove the rubbery ring from the piezoelectric mister disk. It’s not glued on, so it should come off very easily. It should also go back on very easily, which will be important if you decide to use the Vertical Mister method.
2. Place the disk in the approximate center of the sponge, as shown. This step may be easier if you first remove the mister from its control board at the white JST connector, as was done for the above photo. The mister operates best when the bottom of the disk is fully in contact with water, but the top is above water. Placing it on a saturated sponge is a good way to achieve these conditions. [See the Vertical Mister section for another method.]
Step 9: Horizontal Mister System: Placing the Inner Cup
1. Place your net pot on top of the piezoelectric disk. The empty net pot (left) shows the ideal placement of the pot, centered on the piezo disk. However, the mister should work fine even if it’s not exactly centered, as long as most of the disk is underneath the net pot.
2. Finally, cut an opening in the lid for both the wires and the felt. Place the lid on the cup. The lid should push the net pot firmly against the mister (and sponge). If it looks like the top of the sponge is now submerged, you can just pour a little water off through the slit in the lid.
Your mister grow cup is now ready to use.
3. Water can be added manually through the slit in the lid. For an automated design or to water easily via syringe, cut an additional notch on the lid, and insert tubing down to the sponge. Your goal is to maintain a visible water line, while not submerging the top of the sponge. Try not to get to the point where you don’t see any water when looking through the side of the cup.
4. The seeds should sprout a few days after misting begins. After the seeds germinate, switch to water with dilute hydroponic fertilizer solution.
Safety Note: We're pretty certain that it's not healthy to breath fertilizer-water. Don't breath the mist. Once you start using the fertilizer-water, seal the top as much as possible to avoid mist wafting, and turn off the misters before you open the cups to fix anything.
Step 10: Horizontal Mister System in Operation
Here's a video of our mister in action:
Step 11: Automating the Mister
For manual operation, reconnect the white JST connector to the control board. Connect a 5V power supply to the control board. To start the mister, press the button switch on the board. Each button press toggles the mister between the ON and OFF states. For our initial testing conditions, the mister was ON for 1 minute, then OFF for 59 minutes. These times are easily varied. The mister specifications indicate they are capable of delivering 100ml/hr when run continuously, so they should be able to easily deliver 100ml/day.
Since this is tedious to do manually, we connected the mister board to an ESP8266, then uploaded data to Thingspeak to verify operation (see GitHub link for details.) We also attached a DHT22 temperature and humidity sensor. Initially, the humidity reading was useful to verify that the mister was actually misting.
In future iterations, this setup can be used to remotely control and monitor misters, fans, lighting, and water flow. Once optimized, the electronics will be enclosed in a waterproof container, such as a swimmer’s phone pouch with jack.
Step 12: Vertical Mister System: Initial Testing
We wanted to design a system that may work in different orientations and have a potentially larger water reservoir. We detail below some initial testing of the vertical mister system and a drawing of a possible water reservoir design.
Insert the mister, silicone ring still in place, into one end of the PVC fitting. Be gentle. This step may require a bit of fiddling. The goal is to insert the mister far enough into the pipe so that it will stay in place when the pipe behind the mister is filled with water. You’d also like the mister to fit snugly, so there isn’t much leakage around the mister. However, the mister itself is porous, so you should expect a small amount of water to leak through if it sits for a while without running.
Fill the portion of the PVC fitting that is behind the mister with water, keeping the open end of the fitting more or less upright.
Operate the mister as described above in the Horizontal Mister System Steps.
Step 13: Vertical Mister System Reservoir
We envision the vertical mister system connecting to a reservoir similar to the one above.
A hole for the mister could be placed in the side of the cup if it is to be used in the upright orientation, or in the bottom of the cup if it is to be used in a sideways orientation. With a little reconfiguration, it should also be possible to have the mister enter through the top of the grow cup.
In the near term, such the reservoir could be filled manually with a syringe daily. Eventually, we would like to design a fully automated system.
Step 14: Cup Shelf Design and Materials
As mentioned in the introduction, we wanted to space the grow cups in a manner that allowed ample room between cups, for the placement of LEDs. The overarching idea here is that plants are arranged 12 plants (cups) per shelf (layer), on each of three layers, and that each shelf, on its underside, contains LEDs that would provide lighting to plants on a shelf or layer underneath.
At planting, a “shelf” could be positioned slightly below a panel designated as the “ceiling”. A maximum of twelve new plants could be planted at this point in time. As time progressed and plants grew larger, the shelf would move downward. (This could be accomplished manually or digitally with a timing program). As time would continue to progress, a second shelf would be introduced at an appropriate height that it would be both far enough away from the cube’s “ceiling” such that seeds could germinate, and also far enough away from developing plants, that light would be provided to those growing plants by the LEDs on the underside of the new shelf. While two shelves like this allow for plenty of room for plant growth, three shelves would be the maximum number of small plants that could be sustained at a time. For this design, the cups and LEDs are spaced as shown above.
- Three pieces of foam board, ~0.32 cm (⅛”) thick, each cut into 50cm x50cm squares
- 3 ½ ” hole saw blade
- Rubber mallet
- Cutting Tool (Xacto knife/scalpel/laser cutter of your choice)
- 9 oz. Solo cups, as described above LED assembly, see next section
- Spray paint (chrome, to reflect light and also block light from getting to roots)
Step 15: Building the Cup Shelves
1. Draw 8 vertical lines, beginning at the left side of the 50 x 50cm board, at: 1.9 cm (0.75”), 6.4 cm (2.5”), 13.9 cm (5.5”), 21.3 cm (8.375”), 28.7 cm (11.25”), 36.2 cm (14.25”), 43.6 cm (17.125”), 48.1 cm (18.9”).
2. Draw 10 horizontal lines, beginning at the bottom of the board, at: 1.9 cm (0.75”), 6.4cm (2.5”), 11.7 cm (4.6”), 17.0 cm (6.7”), 22.3 cm (8.75”), 27.7 cm (10.9”), 32.9 cm (13”), 38.3 cm (15”), 43.6 cm (17.125”), 48.1 cm (18.9”). Mark and cut 3.5” holes centered on the ‘Pot’ points. We used a 3.5” hole saw and a mallet to make cutting marks, then finished the cut with an Exacto blade. If you stack your foam you may be able to cut all three sheets at once. Each of 3 sheets should have 12 pot holes for a total of 36. (Optional) Mark and cut ~⅛” holes at the ‘LED’ points. Since the goal is simply to be able to find the LED locations from both sides of the sheet, hole size is not crucial. Each of the 3 sheets should have 12 LED holes for a total of 36.
3. Center the hole saw blade over each location marked ‘Pot’. Press the blade firmly into the board. Give the blade a few whacks with a rubber mallet. Finish the cut with a knife.
4. Cut 12 holes in each of the three foam board pieces, for a total of 36 holes. Press the cups into the holes. The rims of the cups should rest on the foamboard, but should otherwise be mostly through the foamboard (see picture below). Note: if you flip the three foam board pieces over before inserting the cups, the markings indicating the locations for the LEDs will now be on the underside of the sheet. This will be helpful when verifying the light arrangement.
5. Once all holes are cut, measure with clear cups, first, to ensure that they all rest in the same manner. Cups can then be spray-painted with a light color. We used chrome spray paint, as it reflects lighting in the box very well, and also blocks light from reaching the roots.
6. Rims of cups rest on the foamboard.
Step 16: Orienting the Shelves
The left image above shows shelves of the cube, placed side by side. The two shelves are identical, but the shelf on the right has been rotated by 180 degrees. Note how, when stacked, the cup holes in the sheet on the right will end up directly under the blank areas in the sheet on the left. Our prototype used foam core, but something more rigid (acrylic) would be more suitable. When stacked, the shelves appear as in the picture below. A maximum of three layers/shelves would yield 36 plants.
The right image above shows two layers, stacked. Note that this photo is taken at a slight angle. If it were taken from directly above, the holes on the top shelf would be directly above the white spaces on the bottom shelf. Correspondingly, the holes on the bottom shelf would be directly below the white spaces on the top shelf. The LEDs are centered in these white spaces, on the underside of each shelf.
Step 17: Light Design and Materials
Our original light prototype only had 12 LEDs (4 LEDs on 3 panels) which we want to reconfigure for this design. Each level of our final design will have 12 clusters of five 1-watt LEDs instead. The below instructions give the basic procedure for building LED lighting arrays, but our final LED panels will look different than those pictured.
Our prototype design pictured below involves sixteen 3-W LEDs per level, which gives 3200-4000 lumens over a 0.25 square m area (12,800 - 16,000 LUX). We don't know the exact PAR, because those specs aren't given with the LEDs, but we chose a combination of cool-white (6500K), warm-white (3000K), and red to give us lots of blue and red light in the spectrum. We know that LUX isn’t the same as PAR, but it provides a useful starting point when working with white light, and is more commonly given in factory specs.
Our improved design will involve clusters of five 1-watt LEDs, two warm-white, two cool-white, one red, some LEDs in each cluster will be wired to separate circuits so they can be turned on and off independently. This improved design will have 12 clusters of LEDs per level. Each cluster of LEDs in the improved design should emit 450 lumens. For a total of 21,600 LUX per level, which should provide for excellent plant growth. We will be able to turn off some of the lights in each cluster individually, if this proves too hot or intense for young plants.
We've based our choice on a few things:
We've successfully grown lettuce close to optimum size (~12 cm tall, 15 cm wide) in 28 days using a 4000 K white light that outputs 7000 lumens over a 0.38 m area (18,000 LUX). We estimate that a 4000K light should have lower PAR than our combo of white and red lights. We found a paper that reported excellent growth of lettuce under white light plus red light at 14,000-18,000 LUX, which is slightly less than what we have. We've opted for mostly white light over red/blue based-grow lights due to the above paper and comments made during the NASA webinars that the folks there thought white light, plus red, might be a good route to go.
Tools and Materials:
- 5 cm (2”) wide x 3 mm thick strip of aluminum,
- ~ 412 cm total length (to be cut into nine 45.7 cm (18”) lengths)
- Power supply - Old design had 3.3 V, 20 A.
- LEDs - Old design had 36 high powered 3 watt LED chips with PCB. New will have 1-watt high-powered LED chips with PCB - 72 cool white, 72 warm white, 36 red
- Resistors (one per LED) - Old design had 36 1Ω 1 watt resistors
- Thermal adhesive such as Arctic Silver Arctic alumina
- Red and black 18 gauge insulated wire
- Electrical tape
- Electrical-grade silicone sealant
- ¼” drill bits
- Drill press or hand drill
- Soldering iron and solder
- Nail, metal punch, or similar (for marking aluminum)
Step 18: Building the Lights: Preparing the Aluminum Strips
1. Cut aluminum stripping into nine pieces 45.7 cm (18”) long. This will function as the primary heat sink for the LEDs.
2. Place 4 clusters of LEDs on each of the nine pieces of aluminum stripping using the following spacing:
- The center of the LEDs should be 10.6 cm (4.2”) apart.
- They should align with the LED markings on the underside of the 3 shelves.
- The 1st and 4th LED should be approximately 4.4 cm (1.75”) from the ends of the aluminum strip
- Mark the positions, then thoroughly clean the aluminum strips.
3. Drill a ¼” hole on either end of the LED strip 1.9 cm (¾”) from the end. These holes are used for attaching the strips to the frame/shelves. Don’t be like us; drill these holes before you start wiring the LEDs.
Step 19: Adhering the LEDs
It’s important that you work quickly so that adhesive won’t set before the LED is secured in place. Check the ‘pot time’ or ‘work time’ on the instructions of the adhesive packaging before starting. Note: Do this step in a well-ventilated area.
1. Place a 2-3 mm bead of the thermal adhesive’s part A and equal sized portion of the thermal adhesive’s part B on a flat, clean, expendable surface.
2. Stir together for 5 or 6 seconds until completely mixed using a popsicle stick or similar.
3. Scrape the paste off the expendable surface and place it on the center of the back of an LED in a large glob.
4. Press the LED into its marked position on the aluminum and secure it tightly, preferably with clamps or screws. That’s not really necessary with LEDs of this power level though it will increase efficiency by a tiny margin.
5. Repeat until all LEDS are in place.
Step 20: Wiring the Light Together
1. Connect the positive terminals of each LED to positive terminal of the unplugged power supply in parallel, generally done using soldering and wire
2.Connect each LED to the resistors on the LED’s negative terminals (resistors are non-polar, so it doesn’t matter which side of the resistor goes to which LED terminal; LEDs, however, are polar).
3. Connect the side of the resistor opposite of the LED to the negative terminal of the unplugged power supply also generally done using soldering and wire.
4. Plug power supply in to test whether or not the lights work.
5. To prevent corrosion and accidental shocks, cover exposed wires with electrical tape or coat exposed metal with electrical-grade silicone sealant.
Step 21: Arranging the Lights
Each of the 36 LEDs is located directly above one of the 36 plant grow cups. Given that the spacing between plant shelves can be varied, this should provide maximum light intensity for each stage of plant growth.
In our next design iteration, each 3-watt LED will be replaced by a group of five 1 W LEDs (2 cool white, 2 warm white, 1 red), at least part of which could be turned off separately. The ability to control the light environment (color profile, intensity) for each individual plant could be useful when conducting experiments to determine ideal growing conditions in space. It would also allow for less light intensity when the plants are young, saving power and reducing heat.
We have nine aluminum strips, arranged into three LED light assemblies, as described in the section above. One assembly is arranged on the underside of the top surface of the cube frame. The two remaining assemblies are arranged on the undersides of two of the three cup shelves. (The bottom cup shelf has no plants below it, so it does not need LEDs on the underside.) Each assembly has 12 LED-clusters, for a total of 36.
In the prototype above, we show a light assembly connected to the top of the cube frame, then a single light strip attached to the bottom of the next shelf down. In the final design, a 3-strip assembly will be attached to the underside of both center shelves.
- Three 3-strip LED light arrays from previous step
- Wire or zip ties - We used pipe cleaners for prototyping, but our final design will be more sturdy.
Attach one LED array to the cube frame in the orientation pictured above. Each LED should be located directly above the center of the plant grow cup below. Similarly, attach a 3-strip LED array to the underside of each of the two center shelves. The strips of each array should be located above the three rows of pots below, with each LED centered on the pot below.
Step 22: Ventilation System Design and Materials
Air movement is important for both plant growth and removing heat from the LEDs lights. Based on the rule of thumb that the CFM in a greenhouse should be roughly twice the footprint, we estimated our cube needed a minimum of 5.4 CFM of air movement in the cube (0.82 CFM airflow per cubic foot of cube volume). To see if this would be in the ballpark for a smaller container, we looked at growth chamber specs. We found a 17 cubic ft growth chamber with 20 CFM airflow (0.85 CFM airflow per foot of chamber volume), which is similar to our estimate.
For heat dissipation, we have read that 3-5 air exchanges per minute are ideal for warm enclosed grow rooms. (Note: We are a bit uncertain about linking to this statement, as we suspect its source is, er, less-than-reputable plant growers, but such growers are usually the ones trying to grow plants in small indoor spaces with homemade equipment.) Based on this exchange rate, we estimate that we need a maximum air exchange of 22 CFM.
In order to promote air movement in the corners and on either side of grow cup shelves, we are opting to use an array of smaller fans on either side of the box, instead of one big one. Our ventilation system consists of six 50 mm, 12 V, 0.12 A fans, that provide ~ 9 CFM airflow each. Their combined 36 CFM should be more than sufficient for heat removal.
We put six matching holes for air intake on the front of the box. On the space station, these could be enlarged slightly and covered with absorbent mesh to reduce the escape of any leaks and debris. The negative pressure sucking things away from the “front” of the box (i.e. facing the cabin area) would also help contain any leaks or debris. On a space station, the exhaust fans could be hooked up to the ISS Express Rack ventilation system.
- Six 50 mm wide x 10 mm thick, 12 V, 0.12 A fans similar to these
- Six three-pin fan Y-splitters
- One switching power supply with output of 12 V, 1A
- 2 jumper wires
- 1 female barrel jack
- Thin wire for attaching fans to structure - We used pipe-cleaners for prototyping, and will use 12 gauge-wire (aka coat hanger) for the final design.
- Hook-and-loop (Velcro)
- Small screwdriver
- Needle-nosed pliers (if working with heavier gauge wire)
Step 23: Building the Ventilation System
1. Connect fan splitters and fans as pictured below. Fortunately, the y-splitters allow you to attach the fans only in the correct configuration.
2. Use the Jumper cables to attach the female barrel jack to the positive and negative pins holes on the first y-splitter. If you follow the line of wire to a fan, the positive wire is the red, the negative is black, and the yellow one is for controlling the fan (and doesn’t matter here).
3.Using wires, attach three fans on either side near the rear of the growth chamber. Fans should be positioned so that they blow air outward. The fans should be positioned at a height that they will draw air over each of the three shelves inside the cube.
4. Repeat fan positioning on other side of chamber with the remaining 3 fans. The wires should be fed under the bottom cup tray.
5. Secure fans to the outtake holes in the outer cover. We will likely use velcro for this for easy disassembly.
Step 24: Giving Credit Where It Is Due:
About the team:
We are competing in the professional category. However, we have dubbed our team “The Amateur Professionals,” due to the fact that none of us are designing things based on our actual profession. We’ve had engineers doing horticulture, biochemists doing lighting design, and entomologists experimenting with metal working tools and Arduinos. We’ve enjoyed the chance to learn new skills.
Jessica Frega - Jessica works in public health, but has never lost her teenage love of space. When not chasing after a 3-year old, she loves to garden, craft, and precisely design things to be cut with computer-guided cutting machines.
Austin Marty- Austin is a recently graduated biochemist, member of Splatspace, and botany enthusiast. He is our lighting designer, as he has ample experience building grow lights for his ever-growing collection of epiphytes and aquatic plants.
Sandra Paa - Sandra is an entomologist turned agronomist who works to develop better fertilizers for plants. She is interested in automation in plant growth systems and is always up for tinkering. Sandra is both a fount of creative ideas, and a useful critic when our ideas become too impractical. She’s had a hand in building many of the grow cube systems from the supports, to the lights, to the cup shelves.
Aurora Toennisson - Aurora is an entomologist, gardener, and wannabe space biologist. She originally instigated the formation of the team, and helped organize meetings for the build team. She worked on testing different growing media and pot sizes, tinkered with water delivery systems, designed the ventilation system, and designed the support structure for the grow cube.
Dawn Trembath - Dawn is a member of Splatspace makerspace, Triangle DIY Biology, and Durham’s Community Lab. Dawn's background is in engineering, though she's spent recent years doing policy work. Dawn designed the mister system, and contributed a ton to group design brainstorming. She plans to use the knowledge from this project to build an automated system to keep her plants alive so she can continue to ignore them while working on automated plant systems.
Julie Hoover - Julie is a former professor and leader of a community college high-altitude ballooning team, and now NASA employee. She recruited several of the team members and has project managed our progress from afar. She is a wealth of knowledge of inexpensive supply sources, strategies for problem solving, and creative uses of dollar store items.
Jimmy Acevedo - Jimmy got his start as a high-altitude balloon team member. He enjoys tinkering at home and uses every excuse to fold Maker culture into his day job. Jimmy is also the graphic designer of the group.
Peter Reintjes - Peter claims he's too busy to be on the team, as he is heavily involved with other projects at Splatspace (and his work designing continuous evolution protein engineering equipment). However, he's given us a lot of advice about tiny fluid delivery systems, so we're counting him as an unofficial advisor.
Runner Up in the
Growing Beyond Earth Maker Contest