Modulus

Kuching, Sarawak | Have seeds will travel!

PCPS - Portable Crop Production System

High-Level Project Summary

PCPS is a collapsible crop production system aimed at fuelling humanity to Mars and beyond. It will be playing a crucial role in supporting the nutritional requirements of a crew on long-duration exploration missions, hence maintaining crew health and performance. When deployed, PCPS takes up a volume of 0.13 m^3, 0.089 m^3 of which is dedicated to the growth chamber, minimising the waste of valuable space. With a stowed volume of just 0.063 m^3 (an astounding 49% of the deployed volume), it is designed to be portable, both on Earth and in space. It also has an integrated automated system with HMI to monitor and control the growth of crops utilising dedicated presets for each crop species.

Link to Project "Demo"

https://youtu.be/1T8TUg3VOtE

Link to Final Project

https://drive.google.com/drive/folders/10DEvfXNt6nI9a9QT5jryspEhqpr6FT2e?usp=sharing

Detailed Project Description

Different parts of the PCPS


Figure 1: Isometric view of the PCPS (left) and folded PCPS ready to be stowed (right)

PCPS is a collapsible crop production system aimed at fuelling humanity to Mars and beyond. The overall dimension of a deployed PCPS is 0.55m x 0.45m x 0.52m, conveniently in the shape of a cuboid and is portable. The deployed volume is 0.13 m^3, 0.089 m^3 of which is dedicated to the growth chamber, minimising the waste of valuable space. When folded, the stowed volume is 0.063 m^3 (an astounding 49% of the deployed volume), it is designed to be portable, both on Earth and in space. The mass of the system is estimated to be around 10 kg, based on SolidWorks’s Mass Properties. 

The bottom part of the PCPS is where the control systems are kept. The control systems include a CO2 supply system, an active watering system, a thermal control system, a humidity control system, a transpired water recycling system, a used water retrieval system, a power distribution assembly and a Programmable Logic Controller (PLC). On the outside, there is a control panel, a Human-Machine Interface (HMI), an array of LED indicators, a water level indicator and refill slots for carbon dioxide cartridges and water. On the sides, there is a set of simple ergonomic handles installed. 

Figure 2: Labelled front view of folded PCPS

Figure 3: Air Control Module in the growth chamber

Figure 4: Labelled bottom view of the PCPS

The function of each component is as follows:

  • CO2 supply system: Filter CO2 from the cabin air and supply it to the plants
  • Active watering system: Sensors detect when the plants need water and keep water flowing as needed
  • Thermal control system: Regulate the temperature in the growth chamber
  • Humidity control system: Regulate humidity of air in the growth chamber
  • Transpired water recycling system: Collect and recycle transpired water in the growth chamber
  • Used water retrieval system: Retrieve remnant of water in the growth chamber prior to shutdown of the system
  • Programmable logic controller: Save the presets of control systems specific to each crop species that will be grown in the growth chamber
  • Control panel: Allows a crew member to switch the PCPS on or off, as well as start, stop or reset the system with ease.
  • Human-Machine Interface: Allows simple and straightforward operation of the PCPS by a crew member
  • LED indicators: Indicate the status of the PCPS
  • Water level indicator: Indicates the water level in the water tank
  • Refill slots: Allows crew members to insert CO2 and water refill easily
  • Ergonomics handles: Allows easy transportation of the PCPS by hand

Figure 5: Labelled growth chamber

The top part of the PCPS is the enclosed growth chamber. The lid of the growth chamber is detachable, and the four walls are collapsible with the help of hinges. Rubber seals and latches are installed to ensure an air-tight enclosure of the growth chamber. The middle sections of the front and back walls are transparent to make the growth area visible. This is beneficial for the psychological well-being of the crew. The lighting system is installed at the bottom of the lid. The four arrays of LEDs provide the light required for the plants to grow.


How does the PCPS work?


Figure 6: Folding process of the PCPS (assembly process is in reversed steps)

Firstly, the PCPS needs to be assembled. The assembly process is deliberately designed to be simple.

  1. Transport the PCPS to the desired deployment location
  2. Lift the walls of the growth chamber and lock them in place using the flexible latches
  3. Snap the lid on using the embedded magnets

There are only three steps that are needed for the crew to start planting

  1. Insert seeds from the seed bank to the growth area
  2. Add water into the water tank and install the CO2 cartridges
  3. Select the system control preset specific to the crop species using the HMI

Figure 7: Water refill standard socket and CO2 cartridge refill mechanism

There are only 2 things that the crew have to do to maintain the operation of the PCPS.

  1. Refill water when the water level is low
  2. Replace the CO2 cartridge if needed

Below are descriptions of how different systems work:

CO2 supply system

Heterogeneous granules of a synthetic rock called zeolite are used to extract CO2 from the cabin air. The CO2 absorbed by the zeolite granules is released into the growth chamber for the plants to breathe by heating the zeolite granules.

In the case when the CO2 concentration is low around the PCPS (or when the PCPS is deployed on Earth where the CO2 concentration in the atmosphere is low), CO2 can also be released into the growth chamber from CO2 cartridges. These refillable cartridges are refilled by the Carbon Dioxide Removal Assembly (CDRA) on the spacecraft. This is a redundancy in the system design to make sure that there will always be enough CO2 for the plants to undergo photosynthesis. 

Note that the current CDRA in use do not store extracted CO2 in cartridges. This is a modification that we suggest in order for better use of the CO2.

Active watering system

Clean water is transferred into the PCPS through the standard input socket on the front panel of the PCPS. The clean water is stored in a water tank. Sensors are installed to check if the plants need to be watered. Clean water is dispensed at the roots when needed. A useful water level indicator is also installed on the front panel for the crew to visualise the water level in the tank.

Thermal control system

Thermometers are installed in the growth chamber to measure the temperature. The growth chamber will be heated or cooled based on the optimum temperature in the preset of the crop planted.

Humidity control system

Hygrometers are installed in the growth chamber to measure the humidity of the air in the growth chamber. If the humidity is too high, the transpired water recycling system is triggered.

Transpired water recycling system

Metal-organic frameworks are paired with heaters to recycle transpired water in the growth chamber. The aluminium-based framework is carefully kept in a container and humid air is allowed to pass through it. The water molecules will be trapped in the framework and can be released by heating it.

Used water retrieval system

Prior to the shutdown of the PCPS, water remaining in the growth chamber will be evaporated and collected in the water tank. The water can then be extracted from the system. Hence, the PCPS will be clean, dry and easy to store when no longer needed.

Lighting system

The lighting system consists of 4 arrays of energy-efficient LEDs installed under the lid. The LEDs emit a magenta-pink light as plants use more blue and red wavelengths. An optional white light is also equipped for viewing purposes.

Proposal for planting system

The problem with the porous clay substrate used in Veggie and Advanced Plant Habitat (APH) is that it is not reusable. Hence, it is not sustainable to bring a lot of them on the course to Mars or any long-duration exploration missions.

Our proposal is to use a sponge-like-structured growth medium made of self-healing polymer. Hydroponic sponges are commonly used in hydroponic farming. Its structure is optimal for retaining water and providing support for the roots of the plants. However, they are not reusable because the roots of the plants cannot be removed from the hydroponic sponges without damaging them. So, we had this concept of making a sponge-structured growth medium made of self-healing polymer. The structure of the growth medium gives it the same advantages as a typical hydroponic sponge. After harvesting, the growth medium can be cut using a scalpel for the roots to be removed efficiently. The self-healing property of the material allows the growth medium to heal and retain its original structure. Once cleaned, it can be reused for the next cycle of planting.

To further improve the aeration and water retention in the self-healing growing medium, perlite or vermiculite can be embedded in the medium. Note that both perlite and vermiculite are reusable.

An alternate proposal is to utilise a mineral substrate mix called the LECHUZA PON. It provides plants with the ideal air-water ratio and micronutrients as well as a stable pH value. Most importantly, LECHUZA-PON can be used for years, without having to be replaced. This will be essential for sustainable transits on long-duration exploration missions.


What benefits does the PCPS have?

  • Each PCPS unit is portable and can be deployed even in tight spaces.
  • Multiples PCPS can be deployed at once (by stacking on top of one another and attached using simple velcro strips for volume-efficient arrangement) to meet the nutritional requirements of a crew of 4-6.
  • The device is stowable/deployable. When stowed, the volume (0.056 m^3) is only 45% of the deployed volume (0.124 m^3).
  • Functional in microgravity and partial gravity.
  • Most of the systems are manufactured using lightweight and durable polymer, keeping the system mass low.
  • The growth chamber is fully enclosed to allow for better-controlled growing conditions for the plants.
  • The use of flexible latches ensures the easy assembly of the system.
  • All components are made of long-lasting material to minimise the need for logistical spare due to the wear and tear of parts.
  • Food safe, citric-acid based sanitiser is used to sanitise the growth chamber at a set interval to prevent the growth of harmful microbes.
  • Easy to clean the surfaces by wiping due to the material selection and surface texture.
  • Built-in redundancies ensure the control systems function as intended, hence minimising the chance of plants wilting/dying.
  • An automated system with HMI allows easy operation and minimal crew interactions.
  • CO2 capturing and water recycling systems minimise resources for operation.
  • Suitable for deployment in arid regions on Earth due to its portability, scalability and efficient use of resources.
  • Relatively low cost and easy to manufacture due to the use of standard components.

Optional add-ons

  • Lead bricks can be attached to the outer walls of the PCPS to shield the plants against Galactic Cosmic Radiation (GCR) and Solar Particle Events (SPE). Consider alternatives such as water, aerogel and astronauts’ faeces.
  • Optional white LEDs in the lighting system so it is easier for the crew to observe and inspect the plants and also comfortable for their eyes.
  • Pairing with solar and wind energy devices when deployed in arid regions on Earth.


Tools used to develop the project

We use SolidWorks for 3D modelling.


4-minute video presentation (part of SpaceApps Sarawak's requirements)

YouTube link: Presentation link

Space Agency Data

We used “Growing Plants in Space” released by NASA to learn about the latest research and plant habitat devices used at the international space station (ISS). The fact sheets of Veggie and Advanced Plant Habitat are particularly useful to learn the technical details of a crop production system in space. The technical knowledge acquired inspired us to come out with a solution that is practical, reliable and innovative. The open-source information about Food Production published by the Canadian Space Agency (CSA) further enhanced our knowledge of an astronaut’s diet in space.

Hackathon Journey

It was an extremely fruitful and enjoyable experience for us. We gained lots of knowledge regarding crop production in space and space in general as well. We learned to work collaboratively and effectively, especially having to work virtually. One of us is already working as an engineer and the other is currently studying engineering. One thing we have in common is our passion for problem-solving! Have Seeds Will Travel is particularly appealing to us because we will be able to engineer a solution for a challenge that has yet to be solved. Being able to attempt such a challenging problem by applying our engineering skills while learning throughout the process is what we look for in this NASA SpaceApps Challenge! The most challenging part is the vast amount of background knowledge needed to make a meaningful attempt at solving the challenge. We made good use of the resources shared by the organiser and resources online to pick up the required knowledge before producing a solution. We are thankful to the organiser and the local lead for this unparallel experience!

References

NASA RESOURCES

CANADIAN SPACE AGENCY (CSA) RESOURCES

EXTERNAL RESOURCES

Tags

#HaveSeedsWillTravel! #PortableCropProductionSystem #portable #crops #plants #seeds #hardware #SolidWorks

Global Judging

This project has been submitted for consideration during the Judging process.

Have seeds will travel!

A viable food system for long-duration exploration missions does not yet exist, but it will be necessary to maintain crew health and performance. Your challenge is to design a deployable crop production system capable of supporting the nutritional requirements of a crew of 4-6 on a transit mission to Mars and back to Earth.