Introduction: Bee Box: a Compact Growth Container for the ISS

By
About: Computer and Mechanical Engineer. Currently a Robotics and AI masters student who loves arts and crafts, cooking, and anything involving making. Find me making cyborgs and space robots in my spare time.

This was created during my (extremely limited) free time during my first semester of my sophomore year in College. I must thank my boyfriend for helping me complete the model on time. I enjoyed being able to try out some practical creativity.

This growth system consists mainly of slides slotted into drawers. There are three subassemblies of this system. The first of these main subassemblies is the slide. Next comes the drawers, which hold the slides. The final subassembly is the frame, which holds the drawers in place and contains the plants. This project is designed to use the clay substrate as used in the current VEGGIE growth system, and most of the changes in the process are in the way the space is used. After doing research and talking to some local farmers, unrestrained typical soil and Hydroponics were out of the question.

Step 1: Research

This was one of the most difficult parts of the project. Even though there are many given papers on this topic I decided it would be best to also research different approaches to the problem, such as different ways to grow plants and the effects of microgravity on the plants. This involved both talking to local farmers about ways that they grow things on earth and reading large academic papers spanning the time of space travel. I ended up integrating this part of the process into my online summer class, compiling all of the useful information (and other information as required by the class) into a research paper.

This paper was very useful in coming up with a realistic design. From the research I found that, due microgravity, it would be a poor idea to use normal soil as the water might not spread to all of the roots of the plants, and, that due to the space constraint and the fact that NASA does not seem to enjoy the possibility of a water leak aboard the ISS, Hydroponics would be off of the list too. Luckily NASA has been doing the research on the type of soil to use and I do not intend to change that. With these things in mind I went to work coming up with different designs that might work.

Step 2: Brainstorming

Even before I had finished researching, I was being flooded with design ideas.

Design 1: the spiky Icosahedron, as seen in the two sketches.

This design consisted of an Icosahedron that had faces made up of triangular planters. It was based upon the idea of a hardware store flower shop, where the flowers are sold in big trays yet each big tray cradles a smaller tray of plants. In this design, the pyramids alternated up and down on each face to make use of all of the space under the plants leaves, since the plants grow in a sort of upside down cone. each pyramid was filled with the baseball field clay like mixture and a plant, with a system of pipes making up the frame. These pipe systems would distribute the small amount of water that each plant needs directly to the pyramid it was in.

Pros:

  • Efficient use of space, inside and out can be used to grow plants
  • Looks really cool
  • Used space under grown plants via alternating triangular pyramid design

Cons:

  • Too complex
  • Lighting location
  • Unrealistic expectations for the size of the plant (estimated root space needed was far less than what it would be)
  • hard to maintain
  • Might float around if incorrectly secured
  • Water issue (wouldn't want a leak)

Design 2: Hexagonal barrel around a light

This design consisted of a 50 cm long hexagonal barrel where each side of the barrel was made up of trays holding plants. In the center of the hexagon there would be a high power light that all of the plants would grow towards.

Pros:

  • Efficient use of space
  • Simple
  • End could also be capped with more plants

Cons:

  • This idea was first envisioned as hydroponics (which was a no. And yes, it could have been redone as non hydroponics but I had fixated on the first design)
  • Light might not be powerful enough to grow the plants efficiently/ might need a really big light
  • Accessing the plants in the back might be difficult (although this could be fixed with slide out trays)
  • wasted space behind the cuts of the hexagon

Design 3: The Bee Box

This one was designed after the other two, once I finally realized that the Icosahedron would be too difficult to manufacture and actually put into use. I have to thank the people at my university who, when shown the other designs said "why not just put it in a drawer". Very vague of them, but it led me to think of this idea.

This design consists of two drawers, each filled with slides. Each of the slides holds 4-8 plants on the front, depending on the size of the plant, and has a detachable LED panel on the back side in order to give light to the plants placed behind it. The slides are also able to be placed at different distances from each other thanks to power rails on the inside of the boxes. The forward most inner face of the drawer holds plants, which are given light by the slide in front of it and so on, ending at an LED panel that attaches to the back. This is the design I ended up going with in the final iteration, as it seemed to have bigger pros and smaller cons compared to my first design, and seemed a more efficient use of space when compared to the second design.

Pros:

  • Efficient use of the space
  • Slides could be rearranged within drawers to allow space for different plants (age wise and size wise)
  • easy access plants
  • could theoretically hold roughly 32-64 plants

Cons:

  • Figuring out a system to power the lights
  • must be manually watered
  • Some wasted space under plants when they grow
  • Could get cramped if too many plants are being grown at the same time

Step 3: Finalizing the Design

Due to the amount of time required by my full time class schedule, I was only able to work on this as a side project, and due to this many of the parts stayed in detailed hand-drawing format until this stage. Over the course of the semester the design was being constantly revised. An overview of each sub assembly can be seen below, with corresponding figures in the image bar.

The whole assembly can be seen in figure one. Pictured are the two drawers, each with a label stating which tray numbers are in the drawer. This tray/slide number idea is not seen in the final cad, but would be implemented via label stickers if the trays/slides were switched between drawers. If not, the labeling could be accomplished via etching or some other permanent method. In these sketches, a notebook is pictured on the front of the drawer. These notebooks are for marking down which plant is in each drawer/ slide and writing down watering schedules or other information that would be useful. This notebook is also not pictured in the CAD assembly as I figured it could be kept somewhere digital or on some other document as the pages might flow around in the microgravity if they were only secured as seen in the drawing, an elastic strap or rigid paper could fix this issue though.

Figure two shows a more detailed drawing of the drawers, containing angles that could be easily missed in figure one, such as the side drawer rails, the power rails for the slides, and the place holder port on the back that allows for power for the LEDs.

The third figure contains the frame, which is probably the part that changes the most from paper concept to 3D concept design, although the main operation behind it has stayed largely the same. Instead of the drawers being on wheels as seen (faintly) drawn into the picture, they are on rails in the 3D file. Also, the frame encloses the top and sides of the drawers in the 3D design.

Figure four contains the slides/ plant trays. These slides as drawn in the figure can hold four plants. The plants are secured into the slides via silicone packets that fit around a triangular version of the current plant envelope as used in the VEGGIE system. The LEDs are powered via female power-strip rails that connect to the male rail inside of the drawer. The slides are designed to be moved as needed to ensure enough room for different plant species. The slides are also able to be taken apart, removing the LED portion from the plant portion. This allows for the maximum efficiency of the space by placing one plant half at the very front edge of the drawer and the other LED half at the back if the drawer. In the preliminary design as pictured above, each drawer was assumed to hold three slides; two in the middle of the drawer and one split with the plant half on the front inner side of the drawer and the LED half on the back side of the drawer. With this set up, the system should be able to grow 24 plants. In the current design of the slides, each slide is pictured with eight silicone packets, while each drawer has three slides, allowing for 48 plants to be grown.

Step 4: 3D Modeling/ Comments About Testing

For the most part, the function and design of each piece stayed the same during the transfer from isometric hand drawing to 3D model.

For simplicity and to allow for some more freedom with the electronics, the LEDs are modeled as a flat, translucent, magenta plastic. The plants have also been left out of the 3D model so that all parts of the box may be seen.

Overview:

The design still consists of two drawers containing slides mounted on a frame. The major changes here are in the frame and the number of pockets per slide. For the frame, a cover was added and more supporting ribs were added. The method of the drawers sliding in and out was also changed from wheels to a slot, as mentioned in the previous section.

Slides:

The slides did not change much compared to the original design, however the pockets were divided in half to allow for more plants. This can be easily changed and interchangeable slides can be made for different plant space needs. For instance, if one plant was more prone to having a larger root structure than a different plant, a slide allowing for more room could easily be switched out in place of the more dense ones. The slides contain a positive contact on one side in the slot and a negative on the other. This was omitted from the model along with the other electronics. In the model, the slides are made of two different parts, not including the pouches. These parts are the front tray that holds the plant pouches and the back LED panel stand in. These have holes that allow them to connect to the front and back insides of the drawers, and when put together they form a slot that allows them to slide into place in the drawer on the would be power rails.

Drawers:

The 3D design of the drawers has 6 possible locations for each slide, allowing the plants to be positioned as needed or slides to be added/removed depending on plant size. Unlike the drawing, the 3D model has a different handle to minimize required thickness of the material. Other than the number of slides and the different handle, the designs are practically the same.

Multiple views of each part has been included in order to let the reader get an idea of the design.

Unfortunately due to time constraints (and gravity), no actual testing of this specific unit was able to be done, although cardboard models and separate plants have been grown to test growth mediums.