Formulation

Meet our Stakeholders

Our stakeholders are divided up into three categories:

Investors, Financial Supporters, and Astronauts
Space Tourism Competition
Future Science and Human Race

The astronauts will be directly impacted by our system since they will be provided with a variety of fresh foods along with minimal interaction with the system. Our financial supporters, NASA's Kennedy Space Center, supplied the funding for the team to produce a prototype of our system and helped to promote innovation in this subject. We also had to consider other space organizations that might be interested in implementing a similar system within their own spacecrafts. The MicroTerra will pave the way for others to grow a sufficient food supply to supplementally sustain a crew on an expedition with minimal crew time.

Image retrieved from:" https://www.indiatimes.com/trending/social-relevance/feeding-astronauts-mars-500000-dollars-nasa-534332.html"

Market Assessment

The project is aimed at space organizations such as those mentioned earlier. NASA benefits from our project in that they will be able to provide fresh foods to their astronaut crews. They can then further adjust the system for longer expeditions. The astronauts in space would be directly affected by our project as they would be having fresh nutrients available to them in addition to the packaged foods. They will interact minimally with the system since it will be autonomous.

Image retrieved from: "https://www.space.com/54-earth-history-composition-and-atmosphere.html"

Global Need

If the MicroTerra can help pave the way for NASA to create a system that the astronauts can use while on an expedition this can greatly impact the world. Not only will the astronauts have fresh foods available to them but they will be healthier, happier, and more prepared to go on longer expeditions with the benefits of fresh greens at their fingertips. This can expand our universal knowledge and open a whole new segment of research.

PESTEL Analysis

The PESTEL analysis allows this project to analyze any factors that it may influence or any external factors that could be affecting it.

Political:
For the political side, the MicroTerra had to consider NASA's standards and expectations of the project, as well as the U.S. government as they fund NASA projects, and the potential usage of this project from other countries.
Economical:
From the economic standpoint, the economy must be in good shape for a large flow of interest to be poured into Space exploration and to allot money to be spent in this sector. Material pricing of components used to create MicroTerra could also have a huge effect on the project.
Social:
What we are currently seeing in today's market is a rise in the potential for Space tourism. This can most definitely affect the project's future as more demand for this sector rises, the more of a need for projects like MicroTerra to be made.
Technological:
From a technological viewpoint, progresses in automation and research can help to advance the technologies within MicroTerra.
Environmental:
For the environmental sector, the laws for production and manufacturing need to be abided by.
Legal:
As for legal implications, as we are providing food to people we need to make sure that the food we produce is up to legal standards.

All of these factors combined can be used to show how the project is affected and how it affects others. These considerations will be taken into account throughout the designing and manufacturing processes.

Current Systems in Place

Image retrieved from: "https://www.businessinsider.com/nasa-astronauts-share-successful-harvest-of-fresh-vegetables-2021-4"

NASA's Veggie

NASA has a space garden they are using for research purposes called the Veggie. The Veggie is about the size of a carry-on luggage and it holds about six different plants. Currently, the plants are grown in a pillow system where there is a clay-based growth media and fertilizer. The pillow allows for the distribution of water, nutrients, and air around the plants' roots.

Image retrieved from: "http://spaceref.com/onorbit/kate-rubins-is-growing-radish-plants-in-orbit.html"

NASA's Advanced Plant Habitat

NASA also has a second system that is similar to the veggie and it is called the Advanced Plant Habitat. This system consists of a lot more sensors and is more of a controlled environment. The water, nutrients, and oxygen get delivered to the roots with the use of LED lights and clay substrate to control the release of the fertilizer. This system does have cameras installed to monitor the growth and about 180 or more sensors.

Research

Image retrieved from "https://integrisok.com/resources/on-your-health/2021/july/what-are-microgreens"

Types of Plants

The types of plants that were considered in the beginning were crops like leafy greens, broccoli, and soybeans due to NASA's prior attempts at growing them in space. However, the time to full yield for some of these plants was not ideal. Broccoli takes 80 to 100 days to harvest, while even a seemingly quicker crop like romaine lettuce, will still take about 60 to 80 days to harvest a fully ready to eat crop. Growing these types of crops would require a lot of space, time, and a need to time everything perfectly in order to have enough food ready for consumption every week.

This provided a large question as to how this project would be able to provide food that can be harvested quickly, have a large yield, and be nutritious. This question was answered with an unlikely hero, Microgreens! Some microgreens can be harvested in under 2 weeks, they do not provide a lot of space to grow, and they are high-yielding. There are also a large variety of microgreens that provide key nutrients that are needed for vital human functions.

Image retrieved from "https://www.marysheirloomseeds.com/products/coconut-coir-sprouting-mat"

Growing Mediums

Simply put, growing plants in space is not the same as growing plants on earth. Microgravity plays a large role in the changes needed for outer space farming to be possible. The first issue that arises is how to water the plants. Water cannot be easily controlled in this type of environment, nor can lose soil. The most common growing method that has been used in research is a clay-based medium. Clay pods are used to control the amount of water the plant receives and has fertilizer mixed in the clay to provides essential nitrates for plant growth.

However, microgreens do not need soil to grow, they can be grown hydroponically. Microgreens can be grown using an absorbent material like cotton to soak in water, and a fibrous material for the roots to attach to, such as coconut fiber. This material can be sown together and have microgreen seeds directly placed within the material to make the growing process that much easier.

Image retrieved from "https://bioslighting.com/grow-light-spectrum-led-plants/grow-lighting/"

Lighting

Lighting is extremely important to plant growth. The use of a specific range of wavelength of light is recommended for optimum growth. 400-700 nanometers is known as the photosynthetically active radiation (PAR) zone where photosynthesis takes place. So including lighting within this range is critical to plant health.

Red and blue light wavelengths sit at opposite ends of the spectrum and are often used in tandem to create a PAR zone. Full spectrum LED lights with variable light color selection will be used to maximize this effect to ensure photosynthesis ensues.

Plants also need a dark period, which is the absence of light. In the absence of light, the plants respire and grow. As contradictory as it might seem, the plants need this time to be able to metabolize efficiently. This being said, the amount of light versus dark time must be established. Microgreens thrive with 12-14 hours of light and use the remaining time to respire in the dark.

Image retrieved from"https://www.watelectronics.com/what-is-arduino-sensor-types-working-and-applications/"

Sensors

Certain sensors will help to indicate when the chamber is in danger of exceeding the optimal zone. Things like temperature, light, and humidity need to be monitored. A list of sensors that have been selected below.

Sensors:

Air Temperature
Water Temperature

Humidity sensor
CO2 sensor
Oxygen level sensor
Light Intensity sensor

Image retrieved from "https://electropeak.com/arduino-mega-2560-original"

Arduino & Components

In order to maintain optimal growing conditions, certain factors need to be controlled. The growing chamber must have a consistent air temperature of about 68-72 degrees Fahrenheit, growing lights on for a specific amount of time a day (dependent on type of microgreen), and a watering temperature of about 50-70 degrees Fahrenheit.

Certain sensors will help to indicate when the chamber is in danger of exceeding the optimal zone. An Arduino microcontroller will be in charge of directing the components to cool the area, pump water into the system, and tell the system when it is time to harvest. C++ will be used to code and integrate the sensors and components all together. A list of components that have been selected below.

Components:

Fan/Cooling System
Lights (LEDs)
Water Pump
Drain Valve
Humidifier/Dehumidifier
LCD Screen
Ethylene Filter

Image retrieved from "https://processsolutions.com/the-benefits-of-industrial-robotic-automation/"

Automation

The current systems that NASA currently has do not have automation. The Advanced Plant Habitat is adorned with a multitude of sensors, but there is no level of automation that takes the information from the sensors into an action to fix anything that gets out of line. The crew members must get involved with the system and fix things manually to ensure the plant's health is not in danger.

Constraints & Key Design Requirements

Crew Time: We want to be able to minimize the amount of time that astronauts need to spend on the MicroTerra so that they can focus on their work and research. We do not want our system to hinder the amount of time that the astronauts have available therefore we are making the MicroTerra as autonomous as possible.

Nutrition: It is necessary for the microgreens to be high in vitamins, antioxidants, and other nutrients to help meet the astronauts' nutritional needs. The packaged foods that they have currently available to them do have nutritional value, but we want the MicroTerra to be able to provide them with a fresh option that supplements their needs.

Space: The size of the system is important because there is a limited amount of space available on the International Space Station (ISS). We want to make sure our system is big enough to hold an appropriate amount of microgreens but small enough where it does not occupy too much space.

Other Factors: We needed to take into consideration the amount of heat that the system gives off so that we could ensure to maintain a cool environment in the cabin. It was also important to take into consideration the amount of water and power that the system needs since there is a limited supply on the ISS.

Literature Review

Introduction:

Indoor farming in space is a solution to the lack of fresh food provided to astronauts in space. Implementing indoor farming would not only provide fresh nutrient-full sustenance to astronauts, but also allow the inhabitants of the ISS to have a sustainable source of food. This would reduce the reliance on the transport ships coming from Earth and possibly allow for longer space voyages down the line.

The purpose of this review is to examine multiple factors that have assisted in the development of the design process of the MicroTerra. Topics that have been researched in depth are the current systems that NASA is utilizing for research, types of viable plant selections, the necessary sensors and components needed to implement in the system, how plants react in space and the specific requirements to ensure healthy plant growth, and the types of mediums that would be the best fit for the specific plant choice. Information on all these topics have ensured that the design is optimized to work efficiently in the harsh environment of space.

Growing plants in space is not a new idea. Scientists have been attempting to grow all types of plants to understand how vast the differences are in growing conditions in comparison to earth’s. The phenomena of microgravity and its effects on earthly things has intrigued the curiosities of some of the greatest minds. Astronauts have conducted multiple experiments in space to understand all the specific differences that plants experience in space and are still. Due to NASA’s past research, it has been established that growing plants in space is entirely viable. There are of course certain conditions that must be met and utilizing special methods in order to produce a plant to maturity, but the possibility to further the production of plant growth for consumption is there.

It goes without saying that not everyday typical applications of home gardening apply to what we would see growing in space. Microgravity causes issues with being able to water plants normally, as water could easily bead off and float away. Water consumption is limited so the type of plant selection is imperative to calculate the need ahead of time. Fabricating the effects of the specific amount of sunlight needed with LEDs to allow photosynthesis to happen is crucial to a plant's health. All these variables and more integrated with one another are what is needed to make Indoor Farming a part of the future.

Methodology of Review:

The resources used for this literature review focused on the development of the MicroTerra, an indoor farming solution in space. Our main resources came from NASA research and their current systems such as The Veggie and The Advanced Plant Habitat System. We also looked into other databases that included an online journal article from the German Aerospace Center, Institute of Space Systems. In selecting literature to review, the author selected research that is backed up by factual evidence and promising sources such as official government sites. For the systematic review selection, the author used evidence from testing and their studies to gather the information. The Veggie research includes studies back to 2015 when it was created. The Advanced Plant Habitat system has studies from 2017. Both these systems are still being improved today and include research up until 2021.

The keywords used in searching for these resources and online journals were: growing plants in space, contained systems, NASA, and ISS. This initial search included articles that were resourceful but then we were able to search for more specific findings. We then used keywords such as NASA’s Veggie, The Advanced Plant Habitat System, and microgreens in space. These findings were relevant to our project and included a lot of information that we were able to implement into our system the MicroTerra.

Overview of Research Studies:

Planting Systems and Process Research

In this review, we have included studies on the most nutrient-rich microgreens, types of planting systems and planting mediums. Microgreens have significant amounts of nutrients packed into tiny vessels. We’ve included five sources on microgreen nutrients. In every source, Broccoli is listed as the most nutrient-dense microgreen (Ingarden), (Goldenrain), (herbponics), (livingfreshfoods), (microgreenscorner). Broccoli is high in calcium, iron, and several vitamins. Radish is also listed on all five of the sources as one of the most nutrient-rich microgreens that is also easy to grow. In four of the five sources, arugula microgreens are mentioned as being rich in vitamins and minerals (livingfreshfoods), (Ingarden), (Goldenrain), (microgreenscorner). All of these sources included the benefits of each individual green and what diseases and complications they would be preventative against.

We included research on plant mediums and which would be best used in our microgravity application. We have information on coco fiber, clay pellet, wool, wood fiber mediums as well as the benefits of weaving our seeds into the medium. We used the information provided through the resources to create a design matrix for choosing the optimal medium. In our case, cocoa fiber was ruled out to be the best option (epic gardening), (agriexpo), (Acta Hortaculturae 2004). In addition to searching for sources, we also requested the opinion of an agroecological expert at our university (Jayachandran, FIU).

This university expert also provided guidance and resources on different types of planting systems such as hydroponic, aeroponic and further we found a porous tube planting. We found that for our application, hydroponics would simply require too much water, for the lack of it in the international space station and for the zero-gravity environment (Mason 1994), we found that Aeroponics would not provide us with the control that we needed (Darling 2020) nor would aquaponics. From a NASA study with a porous tube method (NASA Investigations 1985-1991), we found that this would provide the most control, the least amount of excess moisture, and the simplest farming system.

State of the Art

We also included studies done by NASA on the farming systems they currently have in place. We found that their first system, the veggie system, required too much interaction from the crew (NASA Facts Veggie). Their attempt at reducing this crew time was with the Advanced Plant Habitat which includes more than 180 sensors but still requires crew intervention to add water, install the science and provide maintenance (NASA Facts APH). Both systems have provided an abundance of research for how to grow plants in the conditions of the International Space Station and they continue to improve (ICES 2017).

Findings of Review:

Our findings through this research project have been extensive. There are a few underlying factors that needed to be explored before we could truly invest our time into designing an entire system.

Climate Control:

This is a complicated subject that requires understanding in an immense amount of different fields. These systems not only need to utilize the equipment but have the sensors interact with the environment in a meaningful way. Studies show that the climate of an area is determined by a couple of major factors. The Temperature to Humidity ratio, the amount of airflow through a region (wind), and the type of weather that region is subject to. All of these combined create unique environments. This is very important when creating a contained environment because your system will need to be able to recreate these different environments for the different types of plants decided to be grown. For our system, this section will focus on heat and humidity control by utilizing airflow through the system.

Plants in Microgravity:

This is an extreme subject that has an extremely large amount of untested variables. The only place that is collecting data on the effects of microgravity and plants is the International Space Station currently orbiting the planet. These findings are critical to our project since the goal is to be implemented for space missions. The major facts that have been discovered through research are as follows: Plants’ roots grow down into the soil due to the effect of gravity on the plant. This leaves a large problem for the roots of our space plants. Roots do not like to be exposed to light. In fact, too much light could kill the roots and ultimately kill the plant. There are currently a couple of options that our team is looking into, one of which is the wicking system. This system works like an oil candle. You don't leave the top where the wick is open. The oil could rise to the flame and catch the rest of the oil on fire. In the plant system, there is a tight hold around the bottom of the stem of a clone (Baby plant) allowing the plant leaves and stem to grow towards the light. But, keep the roots below when the restraints have been tied to the plant.

Plants in space also lack a very important nutrient that helps build the cell wall and keep the plant standing. This happens because of the lack of force exerted on the plant in the microgravity environment. This can be seen by inexperienced indoor growers growing tall plants with no air-flow through the system. As your plant grows taller and taller, the stem stays thin and weak. This happens because the plant has never needed to thicken its stem to fight against an outside force.

Water Systems:

Although there is an extensive amount of research on all sorts of different water-based topics, our system will require much more finesse in this area of the project. Water is a vital part of any living organism; however, if not correctly implemented into our contained environment, could be detrimental to the entire ship. So when evaluating the hydroponic systems; we've deduced that the large amount of free-flowing water needed in the farming unit would not be the safest or most effective irrigation method. Aeroponics uses an open-air medium to deliver bursts of misty water to the roots of the plants. The roots are exposed in a section concealed from the grow lights. The more effective way that we have researched is using a system of porous tubes and a water-absorbent medium. This system focuses on delivering water to the growing medium instead of directly to the roots. This would be the optimal design for a microgravity system. Using osmosis to deliver water to the plants from porous tubes through the median. This will also allow us more precision on the amount of water used. Testing the humidity of the medium to see when it needs to be watered again.

Power systems:

This part of our research is crucial to the space aspect of the project. Everything must run on a specific amount of power. There is only this amount of space allowed for a specific system. How many resources need to be allocated for the system to function properly. And finally, given all these constraints, does this new system bring a net gain of energy to the entire ship compared to previous systems. In other words, is it worth developing and implementing the spacecraft?

The different systems that were researched for this project were: LED Lighting, Optic Fiber Lighting, Water pumps, Display screens, Actuators, Microcontrollers, and a control module.

When researching the LED lighting system and the power needed to run an effective contained environment. In the spirit of saving energy, our team explored the possibility of having optic fiber lighting as a light source for our system. This would consist of a couple of light collectors on the outside of the capsule that would direct light into these mirrored cables and transport the light to the system. This could be an issue when traveling in areas that do not receive sunlight. Our team also researched passive ways to deliver water to our system with minimal energy consumption. So we researched how osmosis would work in space. It is already a force that helps transport water to the top of a plant against the force of our earth’s gravity. Could this be recreated and utilized in our contained environment?

Discussion and Implications:

Based on the finding of this research we will continue to look into the effects of microgravity on plants, and continue to look into growing plant in the porous tube and wicking system. we also start to due more research into automation of growing plants. All of this knowledge will help us develop MicroTerra, our indoor farming solution.

Resources:

Arun. (2021, March 15). Top 6 healthiest microgreens. Goldenrain Microgreens. Retrieved December 1, 2021, from https://www.goldenrainmicrogreens.com/top-6-healthiest-microgreens/.

Brown, C. S. et all,. (1992). A summary of porous tube plant nutrient delivery system ... NASA. Retrieved September 22, 2021, from https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19920018634.pdf.

Coconut coir: What it is and which to get. Epic Gardening. (2021, August 1). Retrieved December 1, 2021, from https://www.epicgardening.com/coconut-coir/.

EspirituFounder, K. (2019, February 7). Hydroton (expanded Clay Pebbles) growing guide. Epic Gardening. Retrieved December 1, 2021, from https://www.epicgardening.com/expanded-clay-pellets/.

Irigoyen, I. et all,. (2004, January). Wood fiber as growing medium in hydroponic crop. WOOD FIBER AS GROWING MEDIUM IN HYDROPONIC CROP | International Society for Horticultural Science. Retrieved September 2021, from https://www.ishs.org/ishs-article/697_22.

Living Fresh Foods. (n.d.). Top 6 healthiest microgreens. Living Fresh Foods. Retrieved December 1, 2021, from https://livingfreshfoods.com/f/top-6-healthiest-microgreens.

Long, B. (2012). The Ez Guide to aeroponics, hydroponics and Aquaponics. Bonjour Limited Holdings LLC.

Mason, J. (2000). Commercial hydroponics: How to grow 86 different plants in hydroponics. Simon & Schuster.

Microgreens Corner, & Jesper, W. are J. &. (2021, August 11). The 14 most nutritious microgreens to grow and eat. Microgreens Corner. Retrieved December 1, 2021, from https://www.microgreenscorner.com/the-most-nutritious-microgreens-to-grow-and-eat/.

Mineral wool growing media. The B2B marketplace for agricultural equipment. (n.d.). Retrieved December 1, 2021, from https://www.agriexpo.online/agricultural-manufacturer/mineral-wool-growing-medium-5192.html.

Monje, O., Richards, J. T., Carver, J. A., Dimapilis, D. I., Levine, H. G., Dufour, N. F., & Onate, B. G. (2020). Hardware Validation of the Advanced Plant Habitat on ISS: Canopy Photosynthesis in Reduced Gravity. Frontiers in plant science, 11, 673. https://doi.org/10.3389/fpls.2020.00673

Morrow, R., Wetzel, J., Richter, R., & Crabb, T. (2017, July 16). Evolution of space-based plant growth technologies for Hybrid Life Support Systems. TTU DSpace Home. Retrieved December 1, 2021, from https://ttu-ir.tdl.org/handle/2346/73075.

NASA. (n.d.). Retrieved December 1, 2021, from https://www.nasa.gov/sites/default/files/atoms/files/human_exploration_and_operations_committee_report.pdf.

Sempsrott, D. (2021, June 23). Plant habitat-04. NASA. Retrieved December 1, 2021, from https://www.nasa.gov/content/plant-habitat-04.

Top 5 microgreens you must grow at home. Herboponics. (2018, December 30). Retrieved December 1, 2021, from https://herboponics.com/blogs/hydroponics/top-5-microgreens-you-must-grow-at-home.

Walker, D. (2021, June 11). The 6 most nutritious microgreens that beat regular Veg - Ingarden Nutrition. Superfood Microgreen Growing Kit - Indoor Garden. Retrieved December 1, 2021, from https://ingarden.com/blog/nutrition/most-nutritious-microgreens/.

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