Farming in space has many challenges, ranging from the availability of farm space to water and other resources. In space settlements, the living area would be very much limited but the yield must be high to sustain the continuity of life. Traditional soil based farming system cannot be adopted in space settlements as they have many disadvantages. Some of the disadvantages are mentioned below-
- Soil particles can float and get into the eyes of the astronauts as the gravity is very weak or almost nil. These can pose as a potential threat as these particles can also get into the mechanical parts of the settlement and potentially destroy it.
- Plants diseases and the problems of pests and weeds are all related to soil and and can be responsible for destruction of the yield of plants.
- Roots of plants go deep into the soil to reach for water. These take up more space for the plants to grow.
- Soil based farming would lead to a lot of dirt which would be hard to clean off.
All the above mentioned problems can be prevented if we opt for soil-less farming techniques. The hydroponic growing system is a step towards this. It is a system of growing crops without soil, often called soil-less farming. In the hydroponic system, the plant roots grow in a liquid nutrient-rich solution.The nutrients in the solution are adjusted to suit the requirements of the particular plants that are grown.
Hydroponic farming system can help us to solve many problems and give us sufficient yield to support life in constrained environments where the resources are limited. Below are highlighted some of the benefits of Hydroponic farming system-
- Hydroponic farming system take up 90% less water then traditional farming system. In space, water is one of the main resources for the survival of space travelers but it is also in limited quantity. Traditional farming take up a lot of water and can lead to crisis of water which can be a threat. But on the same time, space travelers would also need food to eat. Hydroponic farming systems rely on the recycling of water in which the same water can be recycled to the plants by adding the required nutrients.
- As the plants are in direct contact with water, the roots do not need to go deep in search of water. This can help to grow plants in lesser amount of area.
- Problems like weeds, pests and plant diseases can be prevented as they are related to soil. In the case of Hydroponic farming systems, there is no soil involved. This reduces the use of pesticides and other harmful chemicals in the growth of plants.
- The harvest time of crops is very less as compared to soil-based farming. Considering that food is limited in the space colonies, crops can be grown faster to support life.
Crops grown from Hydroponic farming system are very organic as no harmful chemicals are involved. Only the required nutrients are supplied through the running water. Food from these crops contain more nutrients.
Non-technical Aspects of the system
After carefully researching all the possibilities in the space environment, I have designed a miniature version of the Hydroponic Farming System by considering the rules of the challenge to keep it within 1m3 of space. I have prepared a 3D model of the proposed design where I have highlighted the main components if the system. The final prototype can be a bit different from the early 3D model considering that their might be changes in the dimensions of the parts I will use. Below is a picture from the 3D model I made initially-
In the model, the upper half would be a hollow half cylinder of radius 30 cm. One-third of the hollow half cylinder would be fixed and two-thirds of it would be in a sliding mechanism, where it could be slid up so that the plants inside can be monitored for their growth. The sides of the half cylinder and the curved surface of the half cylinder would be made of special glass (I will be using fiber glass sheet) so that the heat from the sunlight that enters into the system won't escape out and form a greenhouse-like effect. The amount of sunlight in space can be limited (in Mars, only 60% of sunlight compared to Earth is available) and hence a greenhouse system can help to contain the heat from sunlight for a long time. The curved surface can also help to prevent the loss of water particles from evaporation. Due to the curved surface, the water particles can slide down to the ends of the curved surface where a small drainage system would be attached to collect the water and take it back to the water tank.
The lower half of the system would be a box of dimensions of 90 cm length, 60-65 cm breadth and 30 cm height. The box could be opened from three sides. The front side can be opened so as to access the control systems and electronics present at the bottom of the box. The other two sides can be opened so as to assemble the hydroponic pipes and the system of pipes. Also at the time of harvesting, the pipes can be taken out from one of the side so as to harvest the crops. The sides would also be used to attach the water pipes to the hydroponic pipes.
The bottom of the box would be divided by a partition. The bottom would contain the water tank in one side and the pumps needed to transfer the water to the plants. The other side of the bottom would contain the control panel and other equipment. The water tank would be made of black UV protected material so that the radiations do not effect the chemical compositions of the nutrients. The water must be mixed with nutrients at certain intervals of time so that the plants constantly get the nutrients. Different plants need different types and amounts of nutrients. Depending on the types of plant grown, the nutrients can be mixed.
The plants would be allowed to grow in cylindrical pipes. There would be small holes in the pipes where the plants in some soft cases made of coconut husks can be put. In the image below, the cones represent the plants. The coconut husk cases can be of radius 6 cm. The length of the pipe would be around 85-90 cm. A single pipe can accommodate up to 8 plants.
The plants seeds need to be germinated in special conditions. For hydroponic farming system, the seeds need to be germinated first and then transferred into the hydroponic pipes. The seeds are put into soft coconut husk cases where they germinate. After germination, the the seedlings need to be taken care for about a week and then can be transferred to the hydroponic system.
The hydroponic pipes would be of radius 7 cm. In total, there would be 2 layers of hydroponic pipes (less layers initially) with around 20 cm gap in the vertical direction so as to ensure the best growth of plants. The horizontal layers of pipes would contain different number of pipes so as to keep a distance of around 6-8 cm in between the pipes in the horizontal direction. Every pipe in each layer would be connected to a pipe which would carry nutrient-rich water from the water tank. The other side of the hydroponic pipe would be connected to another pipe which would carry the used water back to the water tank after filtering it. The same water can be reused over and over again and prevent the loss of water.
Technical Aspects of the system
The main brain of the Hydroponic System would be the Raspberry PI 4 which would be connected to all the sensors and water pump, air pump and other sensors.
Components used-
- Raspberry Pi 4
- Enviro HAT for Raspberry Pi
- Automation HAT Mini
- PICO HAT Hacker
- Electric Water pump
- Buzzer for alarming
- Air Pump
The Enviro HAT would be used to control the water pumps to send the nutrient-rich water from the water tank to the hydroponic pipes. The LCD screen onboard it can help to monitor the operating voltage and current of the water pumps. The water pumps would be operating for 10 minutes duration for every 15-20 minutes. This time gap would give the plants the time to absorb the nutrients from the water.
The Automation HAT mini would be used to monitor the temperature and pressure of the the greenhouse system so as to make it suitable for the plants growth. The humidity sensor would monitor the humidity and if the humidity is not within permissible ranges, it would give out a warning. The LTR559 light and proximity sensors can be used to monitor whether the plants are receiving the correct amount of sunlight. The MEMS sensor can be used to monitor if sound waves from neighboring machines are disrupting the plant growth. If the plants are near to some to sound waves producing equipment or machines, then the correct measures can be taken to prevent it. The outer layer might be insulated with sound-proof material to prevent disrupting sound waves.
The PICO HAT Hacker for Raspberry Pi would help to connect both the Enviro HAT and the Automation HAT to the Raspberry Pi.
All the data collected from the sensors would be saved in the Raspberry Pi 4 and would be sent to a control panel of the admin or operator who can monitor the growth of plants and the conditions of the hydroponic greenhouse farming system. If there are any anomalies in the system, the operator would be alerted through buzzers and also display warning systems in the computer display. The operator can control the operating of the water pumps and also change the operating timings of the pumps.
Once, I start working on the project, I will include more ideas so as to make the hydroponic system more effective. I will try to include more sensors.
NOTE: I have not included anything on the air supply for the plants as this needs a more research and supervision. I would like to interact with the Element 14 community to take their guidance and ideas. Plants can metabolize carbon dioxide in the air to produce valuable oxygen which can be used by the space residents. This could also help to recycle the air which is also limited in space. Growing plants in space may provide a psychological benefit to human spaceflight crews.
If time permits, then I intend to use a second Raspberry Pi 4 along to monitor the growth of the plants with the help of camera. The second Raspberry Pi would be responsible for all the image processing and machine learning part. I will use the PlantCV library from Python as the main library for the image processing.
I would like to thanks the Element14 team for giving me this opportunity for this challenge. Also, congrats to all those selected for the '1 meter of Pi' design challenge. Let's start working on our projects.
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