Foundation: SeedShuttle - Growing Beyond Earth

Hullo! This is a collegiate submission by GroTech @ Berkeley, a student search constitution dedicated to the design and founding of agricultural technologies. We let designed a imbe growth chamber for Phase I of the Growing Beyond Earth (GBE) Maker Contest. The oblique case is to "plan a implant growth chamber for use in space that makes effective and inventive use of the open volume on ballistic capsule (a square block 50cm of a side), while also incorporating the required features for plant growth (sufficient lighting, irrigation, and beam circulation)." - GBE Manufacturer Contest Overview Sri Frederick Handley Page

To start, we identify design constraints:

  1. International Space Station (ISS) conditions: 50cmx50cmx50cm space and microgravity
  2. Required features for plant outgrowth: light, nutrients, water, space, air, temperature
  3. Plant of interest: Johnny's Seeds' 'Outredgeous' Red Cos lettuce
    • Leaf principal grows to approximately 15cm in height and 15cm in diam at full maturity after about 28 days of development
    • Roots require minimal 216cm³ volume with 6cm of profundity
    • Seeds sowed at 1/8" astuteness for germination
    • Requires approximately 100mL daily
    • Grows best at temperatures of 16-18°C (60–65°F)

With these design constraints in mind, we immediately move to the amusive part: design! We primarily understructur the spatial arrangement of our plants on 'Outredgeous' Red Romaine Lettuce geometry:

  1. Mature lettuce is shaped like an upside-down strobile. Past arranging plants to grow outward radially rather than grow upwards linearly, we minimize unused volume between conterminous plants. [See lettuce image 1 above.]
  2. When we dress octet columns of plants radially within a cube, in that respect are two different volumes for ontogenesis (towards side of regular hexahedron and towards edge of cube) thus we swag planting. [Escort lettuce see 2 higher up.]
  3. When plants at the latter growth stage are mature, we harvest. New plants are inserted and the eight column arrangement is rotated 45° so plants at the earlier increment phase now occupy the volume of the harvested plants. [See lucre image 3 above.]


We attain a radial design for our plant growth chamber, which we affectionately name SeedShuttle. SeedShuttle has three layers with Eight plants each (with cyclic growth phases). SeedShuttle houses a totality of 24 plants and yields 12 fully grown heads of moolah every 2 weeks, a four-fold increase in production compared to National Aeronautics and Space Administration's Veggie, which houses a total of 6 plants and yields 6 mature heads of lettuce every 4 weeks.


The following steps speak additional design choices based on ISS conditions/plant growth requirements and detail the construction of our prototype in sequential format:

Supplies

Dance step 1

  1. Medium density fiberboard (MDF)
  2. Al L channels
  3. Transparent acrylic resin
  4. Hinge (x2)
  5. Bolt Lock

Step 2

  1. Light-emitting diode light strips
  2. Mirrorlike tape

Whole step 3

  1. 3D-printing PLA
  2. Felt
  3. Guar gum (as glue)
  4. Seeds
  5. Calcined remains substrate
  6. Slow-acquittance fertilizer
  7. Froth gaskets

Abuse 4

  1. Irrigation tubing
  2. Syringe (for manual water injection)
  3. Water system pump (for automatic irrigation)

Step 5

  1. Hardwood
  2. 3D-printing PLA

  3. Lazy Susan bearing (x2)

Maltreat 6

  1. Small fan
  2. 3D-impression PLA

Step 7

  1. Stepper motor
  2. Belt
  3. Central artificial lake
  4. 360° rotation solenoid
  5. Arduino microcontroller

Step 1: Enclosure | Construction a Transparent Box

The plant growth bedroom will be placed in a National Aeronautics and Space Administration EXPRESS Torment, which is accessible only at one side.

We choose transparent textile for the enclosure walls so that astronauts can visualize and monitor the growth of the plants.

  1. Construct a 50cmx50cmx50cm box with medium density fibreboard (MDF) sheets for the top and bottom, connected by four aluminum L channels as edges.
  2. Bond transparent acrylic paint sheets to three of the four open sides.
  3. For the remaining root, attach another guileless acrylic sheet to an L TV channel via a hinge, allowing the sheet to swing out look-alike a door. (This go with, the access point, will be known arsenic the front.)
  4. Strong the door with a bolt lock.
  5. Put back an additional acrylic mainsheet 5cm above the bottom MDF A a partition: electronics will be housed below spell plants will be placed higher up.
  6. Since a portion of the acrylic partition obstructs insertion/removal of pots in the lower layer, cut that portion and mount it to the door. When the door is opened, this portion swings come out along with the door.

Step 2: Lights | Attaching LEDs

Under microgravity conditions, lights dictate the directivity of plant growth.

We decide to role red-blue LED strips because plants primarily absorb red and blue luminance; LED strips are relatively slim, allowing many space for plants.

Between LED strips and plants, there must be a minimum clearance of approximately 5cm so that light can reach each flick; this also prevents plant stress collect to heat emitted from LEDs.

  1. Set out three LED light strips on to each one wall (including the door) such that all light strip is aligned with one layer of plants.
  2. To ensure that the plants at the top and bottom stratum receive a exchangeable amount of light every bit the plants midmost bed, coat the top MDF flat solid and the acrylic sectionalisatio with reflective tape.

Step 3: Soil | Aggregation Pots

Roots require irrigate and oxygen, so we take an assimilatory yet porous soil substratum: calcined clay (we choose solid outgrowth media because fluid growth media cannot easily continue a homogenous variety of some irrigate and oxygen in microgravity).

An choice substrate that may satisfy piss and oxygen requirements while trending away from solid media is polyfoam; this foam has high porousness and consequently low density, making it more than cost effective than calcined clay to send to space. We choose calcined clay for now because its use has been validated connected the ISS.

To mitigate microbial growth, we build our pots with lighting-blocking material (to ward off photosynthetic invaders!) and habituate slow-release fertiliser A our method acting of nourishing delivery.

We isolate plants by flourishing one implant per hatful, in order to keep competition and cross-contamination.

Sowing millimeter-turkey-sized seeds at a precise germination depth under microgravity conditions is difficult; thus seeds must glucinium secured on Earth soh that they maintain the wanted depth while in space.

  1. 3D-black and white tetragon pots so that eight pots fit together in an octagon. In this arrangement, lettuce heads tail end grow up to 7.5cm in height/diameter (growth towards the enclosure sides) or 15cm in height/diameter (increment towards the enclosing edges); the height measurements account for the 5cm lighting clearance.
  2. Each pot is 6cm tall and 15cm in duration and has deuce compartments for the following: substratum (216cm³ loudness for roots) and reservoir. These compartments are divided by a reservoir roadblock.
  3. Cut orthogonal wicks from mat up and cut-in wicks through the slit in the reservoir roadblock.
  4. Glue the seed to the taper with guar gum to ensure it maintains the coveted 1/8" germination deepness.
  5. Cadence slow-release fertilizer and calcined the Great Compromiser substrate in the ratio of 7.5g fertilizer to 1000cm³ dry substratum.
  6. Mix fertilizer and substrate equally and then pour the mixture into the substrate compartment without burying the wick.
  7. Attach a lid to the wad and sandwich the taper between a foam gasket such that it protrudes from the substrate compartment.

Step 4: Water | Initiating Plant Ontogeny

A passive irrigation method, such A wicking, saves valuable astronaut time and energy on the ISS. For from each one pot, a wick conveys water from the reservoir to the substrate via capillary military action.

  1. Install irrigation ports to each reservoir compartment.
  2. Initiate plant growth by pumping water through the irrigation port via a blue-collar syringe Beaver State a urine pump and tubing system.
  3. Each plant requires just about 100mL of water day-after-day during each of the 24 days of growth. Since pot reservoirs at plangent capacity hold more or less 450cm³ volume of water, water must be pumped into the reservoir at least Little Phoeb multiplication within 24 days.

Step 5: Space Scaffold | Installing a Rotating Gun barrel

A central scaffold secures pots in situ; this rotating barrel enables accessibility for maintenance and accounts for the staggered growth phases.

  1. Construct a hardwood scaffold consisting of four panels connected perpendicularly to a vertical octogonal tube. The quaternity panels create three layers of space that accommodate eight pots per layer.
  2. 3D-print clips and mount them to the panels; pots are secured by snapping into the clips.
  3. Mount Lazy Susan bearings on the top and bottom of the scaffold for rotation. Then install the scaffold in the center of the enclosure.
  4. Since plant growth phases are staggered away 14 days, the barrel is rotated all 14 days.

Measure 6: Air | Installment a Fan

Under microgravity conditions, air stagnates thus plants tail end suffocate. A fan displaces air so that CO2 circulates in and oxygen unsuccessful. Air circulation also helps regulate humidity and temperature.

On the ISS, air (atomic number 6 dioxide and oxygen levels), humidity, and temperature are regulated, so we pick out to have an open system.

  1. Cut a moon-round hole through the center of the top MDF sheet and riding horse a small fan inside to provid airwave intake.
  2. Backing a 3D-written spacer 'tween the bottom of the scaffold and the bottom MDF canvas so that air can move from the scaffold interior to the plants.
  3. Make up several slits in the transcend MDF sheet for broadcast to scat.
  4. When the fan is inverted on, air enters through the round top of the enclosure, passes finished the interior of the scaffold, exits through the bottom of the scaffold, circulates around the plants, and escapes direct the top of the enclosure.

Step 7: Automation | Incorporating Electronics

Our design should scale such that maintaining multiple growing chambers at once is abundant. Who wouldn't want that! In this section, we identify electronics and propose mechanization.

  1. Domiciliate electronics in the 50cmx50cmx5cm blank at a lower place the acrylic partition. (Excess space English hawthorn hold maintenance tools for measurement and harvest home.)
  2. Install a stepper motorial that rotates the barrel via a belt attached to the bum Lazy Susan bearing.
  3. Install a central reservoir and a water pump that connects to each pot via tubes. (Irrigation tubes will Be loosely coiled exclusive the interior of the barrel and/or attached to a 360° revolution solenoid such that the bbl retains rotational functionality.)
  4. Connect the LEDs, water pump, stepper motor, and devotee to an Arduino microcontroller for automation.
  5. Interface the plant growth bedchamber with the NASA EXPRESS Rack cooling system loops because they can maintain a moderate temperature of 16.1°C to 18.3°C, the perfect growth temperature for our plant of interest.


Growing Beyond Earth is a three-year repugn, with this submission being Yr I. We purpose much future directions regarding mechanization for Twelvemonth II and Class III:

Class 2 | Automate sustainment past coding the following:

  1. A 12-minute light cycle photoperiod.
  2. A 14-day planting/harvesting pedal notification along with cask rotation.
  3. Timed irrigation and central reservoir fill again presentment.


Year III | Automatize planting and harvesting:

  1. Planting: Inset pre-seeded pots and initiate growth with automatic injections of water
  2. Harvesting: Chop mature lettuce with an automatic upended blade positioned in the in advance; remove potful after harvesting.

Step 8: Prototype | Areas for Advance

Although not required for this submission, we stacked a prototype to demo that our aim can equal realistically built. (Side note: our prototype is still in go on, so it features some differences such A cost-effective materials unconventional to those outlined in supplies.)

We reflect on lessons we learned, which we heading to lend oneself to our next iteration of design/prototyping:

  • We grew several plants with non-reusable pots and produced tremendous desert. On the ISS, pots should be reusable. If the pot and substrate can be autoclaved safely and without drastically altering properties, they sack be infertile and reused. Our substrate, calcined clay, is autoclave compatible.
  • When the substrate is sober, wicking requires a longer clock. Priming the substrate for wicking aside irrigating the substrate at initiation volition speed awake the process; the substrate may be primed by injecting water through the fizz gasket.
  • Lastly, an automatic irrigation system is Thomas More complex than blue-collar irrigation in this it requires to a greater extent components: a central reservoir, a water pump, and extra tube. Given the complexity of our proposed automatic irrigation system, we should mitigate potential areas of failure. For instance, we backside forbid entanglement of irrigation tubes by installment a 360° rotation solenoid. Additionally, we could design the system with both self-winding and manual irrigation such that if the late fails, watering is still possible.

Nevertheless, our design SeedShuttle has successfully addressed Phase I of the design challenge by multiplicative constitute production capacity fourfold relative to the baseline, National Aeronautics and Space Administration's Veggie.

We would equal to conclude this submission by thanking NASA, Fairchild Parallel Botanic Garden, and course all the contest partners. Give thanks you for openhanded us college students an chance to learn and collaborate through a truly awesome design challenge. We hope to return for Phase II… until then, continue tempered!

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Send off Team up
Anthony Neil Tan (Team up Lead)
Marlon Fu
Camden Lee
Kevin Atomic number 71
James Rohde
Yujie Wang
Dutch Leonard Wei

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