EPISODE 5: MUSHROOMS ON MARS
VEGGIE PLANT GROWTH SYSTEM ON THE ISS
The Veggie Plant Growth System, often simply called "Veggie," is NASA's primary tool for growing fresh food crops on the International Space Station (ISS). It was designed to investigate how plants grow in microgravity and to provide astronauts with fresh food during long-duration missions. Veggie represents one of the most significant steps toward sustainable life support systems in space and the future of space agriculture.
Purpose and Goals of the Veggie System
The Veggie system was primarily developed to:
1. Provide Fresh Food: Astronauts typically rely on pre-packaged, processed food, which can become monotonous over time. Fresh food, like leafy greens and vegetables, can improve both the nutrition and morale of astronauts on long missions.
2. Study Plant Growth in Microgravity: Understanding how plants grow without gravity’s influence is essential for future space missions to the Moon, Mars, and beyond. Microgravity impacts how plants take in nutrients, grow roots, and produce fruit.
3. Support Future Space Colonies: For future long-term missions or colonies on other planets, it's essential to develop methods to grow food in space. Veggie is a testing ground for closed-loop food production systems that could reduce reliance on resupply missions from Earth.
Key Features of the Veggie System
1. Simple, Open-Air Design:
- Unlike some other plant growth systems, Veggie operates in the open air of the ISS, rather than a fully enclosed environment. The air in the ISS cabin provides the atmosphere for the plants to breathe, which simplifies the system compared to fully controlled, closed-loop systems.
- This open-air design allows the plants to grow similarly to how they would on Earth, but with the added complexity of microgravity.
2. LED Lighting:
- Red, Blue, and Green LEDs: Veggie uses red, blue, and green LED lights to simulate sunlight and stimulate plant growth. Red and blue lights are most critical for photosynthesis, while the green light is used more for the human perception of color and helps the plants appear more natural to the astronauts, which can have psychological benefits.
- Customizable Light Cycles: The LED lighting system can be programmed to mimic Earth’s day-night cycle, or it can be adjusted to provide continuous light to speed up growth. Light intensity can also be controlled to test how plants respond to different conditions.
3. Plant Pillows:
- Growth Medium and Seeds: Veggie uses small pouches known as “plant pillows,” which contain a growth medium (often made from a porous material like clay or a synthetic material), fertilizer, and the seeds for the plants. This growth medium helps anchor the plants in the absence of gravity and provides the necessary nutrients for their development.
- Watering System: The plant pillows are designed with wicks that draw water from a reservoir into the growth medium. In microgravity, water behaves differently than it does on Earth, and the wick system helps ensure that water reaches the plant roots evenly without floating away.
- Nutrient Delivery: The plant pillows also contain time-release fertilizers, which supply the plants with nutrients over the course of their growth cycle.
4. Watering System:
- Watering plants in microgravity is a major challenge because water does not flow or behave the way it does on Earth. The Veggie system relies on the wicking action of the plant pillows to deliver water directly to the plant roots. This prevents the water from floating away or pooling in undesired areas.
- Astronauts manually inject water into the plant pillows with syringes, ensuring the plants receive the necessary amount of water. The pillows are designed to prevent overwatering, a potential risk in space where excess water cannot naturally drain.
5. Compact, Modular Design:
- Veggie is compact and designed to fit within the tight spaces of the ISS. It can be easily mounted inside one of the science racks aboard the station, and its modular design allows additional units to be added as needed.
- The system is relatively low-power, requiring minimal energy to operate, which is an important consideration in space, where energy resources are limited.
Crops Grown in Veggie
NASA has successfully grown a variety of crops in the Veggie system, which have been tested for both their growth patterns in microgravity and their safety for human consumption. Some of the notable crops grown include:
1. Red Romaine Lettuce:
- One of the first crops grown and consumed aboard the ISS, red romaine lettuce has become a hallmark of Veggie's success. Astronauts first harvested and ate this lettuce in 2015 after rigorous testing ensured it was safe for consumption.
2. Zinnias:
- While not an edible crop, zinnias were grown to study how flowering plants behave in space. Flowering plants are more complex than leafy greens, so understanding their growth patterns is key to eventually growing fruit-bearing plants in space.
- The zinnias showed signs of stress and fungal contamination due to excess moisture early in the experiment, but astronaut Scott Kelly successfully nursed them back to health, demonstrating the importance of human intervention in space-based agriculture.
3. Radishes:
- Radishes are fast-growing root vegetables that have been used to test how microgravity affects the development of underground crops. In 2020, astronauts harvested radishes grown in Veggie, which grew normally despite the microgravity environment.
4. Mustard Greens:
- Mustard greens, like lettuce, are leafy vegetables that are relatively easy to grow. They provide important nutrients such as vitamins A and C, and they have been grown successfully aboard the ISS.
5. Mizuna (Japanese Mustard Greens):
- Mizuna is another leafy green vegetable that has been grown in Veggie. Like mustard greens, mizuna grows quickly and provides essential nutrients.
6. Zucchini and Tomatoes (In Progress):
- NASA has also experimented with growing zucchini and tomatoes aboard the ISS, though these are more complex plants that require more time to grow and fruit. Understanding how these plants behave in microgravity is important for future space agriculture.
Benefits of the Veggie System
1. Fresh Food for Astronauts:
- Growing fresh produce aboard the ISS offers significant nutritional benefits to astronauts. Fresh vegetables like lettuce and mustard greens provide important vitamins, minerals, and fiber that are often lacking in pre-packaged, processed space food.
- The psychological benefits of fresh food are also critical. Long-duration missions can be monotonous, and the ability to grow and eat fresh produce can boost morale and provide astronauts with a sense of connection to Earth.
2. Reduced Reliance on Resupply:
- While the ISS still relies on resupply missions to bring food and other essential supplies from Earth, the ability to grow food in space represents a step toward self-sufficiency. This is particularly important for future missions to Mars, where resupply from Earth will be infrequent or impossible for extended periods.
3. Plant Science Research:
- Veggie serves as a platform for studying how plants grow in microgravity. This research is crucial for understanding how to develop sustainable agriculture in space. It helps scientists learn about root growth, nutrient uptake, water distribution, and flowering behavior in the absence of gravity.
- These experiments are key to developing plant growth systems for long-duration space missions or planetary colonies, where astronauts will need to grow their own food.
4. Psychological and Emotional Well-Being:
- Beyond nutrition, growing plants has shown to improve astronauts' mental health. Tending to plants, watching them grow, and interacting with living organisms offer emotional and psychological benefits in the otherwise sterile environment of a space station.
- NASA considers this connection to Earth, through nature and food, an important factor in maintaining astronauts’ morale during extended missions.
Challenges of the Veggie System
1. Microgravity Effects on Watering:
- One of the most significant challenges in space agriculture is how water behaves in microgravity. Without gravity, water doesn’t naturally flow through soil or substrates as it does on Earth. In microgravity, water tends to form floating globules or cling to surfaces due to surface tension.
- The Veggie system addresses this by using plant pillows and wicks to deliver water directly to the plant roots. However, over- or under-watering can still be a challenge, requiring careful monitoring by astronauts.
2. Contamination and Fungal Growth:
- The open-air design of Veggie makes it susceptible to contamination from fungi, bacteria, and mold. On Earth, plants rely on gravity and air circulation to help manage moisture and prevent the buildup of fungal spores. In microgravity, moisture can accumulate, creating a favorable environment for mold growth.
- For example, the zinnias grown on the ISS experienced fungal contamination, requiring human intervention to save the plants. This highlights the need for vigilant monitoring and moisture control in space plant growth systems.
3. Limited Crop Variety:
- While Veggie has been successful at growing leafy greens and some flowering plants, it has limitations when it comes to growing more complex crops like fruiting vegetables (e.g., tomatoes and peppers) or root vegetables (e.g., carrots and potatoes). These crops require more advanced systems to manage water, nutrients, and light cycles.
- As a result, NASA is working on more advanced plant growth systems like the Advanced Plant Habitat (APH)to grow a wider variety of crops.
Future Developments for Veggie
1. Expanded Crop Selection:
- NASA is working to expand the variety of crops that can be grown in Veggie. Future experiments will focus on more complex plants, including fruiting plants like tomatoes and strawberries, and underground crops like potatoes and carrots.
2. Integration with Advanced Plant Habitat (APH):
- Veggie is just one of several plant growth systems aboard the ISS. The Advanced Plant Habitat (APH) is a more controlled, closed-loop system that allows for greater precision in managing environmental conditions like temperature, humidity, and light. Integrating data from Veggie with experiments conducted in the APH will help NASA refine its understanding of how plants grow in space.
3. Closed-Loop Food Production:
- While Veggie currently operates in the open air of the ISS, future systems will need to be more self-contained and capable of integrating with waste recycling and air purification systems to create a fully closed-loop food production system. This will be essential for long-term missions to Mars or lunar colonies, where astronauts will need to rely entirely on their own resources.
The Importance of Veggie for Future Space Exploration
The Veggie system on the ISS represents an important step toward sustainable food production in space. By allowing astronauts to grow and eat fresh produce, it contributes to their health and well-being, while also providing critical insights into how plants behave in microgravity. The research conducted with Veggie is paving the way for future missions to the Moon, Mars, and beyond, where astronauts will need to grow their own food as part of closed-loop life support systems. As NASA and other space agencies look to expand humanity's presence in space, systems like Veggie will be key to ensuring the sustainability and success of long-duration space exploration.