Human Processing Plant: Sustaining Life in Space Through Plants
As humans venture further into space, the integration of plant systems becomes crucial for both psychological and physiological well-being. Plants are not just for aesthetic purposes; they play a vital role in providing essential nutrients and supporting mental health during long-duration space missions.
The Importance of Plants in Space
We already know from our pioneering astronauts that fresh flowers and gardens on the International Space Station create a beautiful atmosphere and let us take a little piece of Earth with us on our journeys. They’re good for our psychological well-being on Earth and in space.
Simply packing some multi-vitamins will not be enough to keep astronauts healthy as they explore deep space. A lack of vitamin C was all it took to give sailors scurvy, and vitamin deficiencies can cause a number of other health problems.
Right now on the space station, astronauts receive regular shipments of a wide variety of freeze-dried and prepackaged meals to cover their dietary needs - resupply missions keep them freshly stocked. When crews venture further into space, traveling for months or years without resupply shipments, the vitamins in prepackaged form break down over time, which presents a problem for astronaut health. NASA is looking at ways to provide astronauts with nutrients in a long-lasting, easily absorbed form-freshly grown fresh fruits and vegetables.
Veggie: A Space Garden
The Vegetable Production System, known as Veggie, is a space garden residing on the space station. Veggie’s purpose is to help NASA study plant growth in microgravity, while adding fresh food to the astronauts’ diet and enhancing happiness and well-being on the orbiting laboratory.
The Veggie garden is about the size of a carry-on piece of luggage and typically holds six plants. Each plant grows in a “pillow” filled with a clay-based growth media and fertilizer. The pillows are important to help distribute water, nutrients and air in a healthy balance around the roots. In the absence of gravity, plants use other environmental factors, such as light, to orient and guide growth. A bank of light emitting diodes (LEDs) above the plants produces a spectrum of light suited for the plants’ growth.
To date, Veggie has successfully grown a variety of plants, including three types of lettuce, Chinese cabbage, mizuna mustard, red Russian kale and zinnia flowers. The flowers were especially popular with astronaut Scott Kelly, who picked a bouquet and photographed it floating in the cupola against the backdrop of Earth. Some of the plants were harvested and eaten by the crew members, with remaining samples returned to Earth to be analyzed. One concern was harmful microbes growing on the produce.
Future Prospects for Veggie
Our team at Kennedy Space Center envisions planting more produce in the future, such as tomatoes and peppers. As humans expand space exploration farther from Earth, the ability to grow a supplemental food crop is a solution to the challenge of long-duration missions into deep space.
Advanced Plant Habitat (APH)
The Advanced Plant Habitat (APH), like Veggie, is a growth chamber on station for plant research. But unlike Veggie, it is enclosed and automated with cameras and more than 180 sensors that are in constant interactive contact with a team on the ground at Kennedy, so it doesn’t need much day-to-day care from the crew. Its water recovery and distribution, atmosphere content, moisture levels and temperature are all automated.
APH had its first test run on the space station in Spring 2018 using Arabidopsis thaliana (the “white mouse of the plant research world”) and dwarf wheat.
Arabidopsis-GRO Consortium Study
Dr. Norman Lewis is the principal investigator for the Arabidopsis Gravitational Response Omics (Arabidopsis-GRO) consortium study, which will be the first study using APH. A key question they want to answer is the relationship between microgravity and plant lignin content. Lignins in plants have functions whose closest analogy is that of bones in humans. They give structure and rigidity to plants and the means to stand upright against gravity. We already know space causes bone and muscle loss in humans because the physical demands are lower in space.
Lewis and his team also want to know if plants genetically engineered to have less lignin can survive and function normally in space. This could give space-grown plants several advantages, including being better for nutrient absorption when humans eat them and in making plant waste easier for composting.
Biological Research in Canisters (BRIC)
The Biological Research in Canisters (BRIC) is a facility used to study the effects of space on organisms small enough to grow in petri dishes, such as yeast and microbes. Right now, BRIC-LED is undergoing hardware validation tests. Scientists want to ensure the LEDs don’t get too hot for the plants and do other system checks.
Soon, researchers such as Dr. Gilroy is interested in how the Arabidopsis plant’s gene expression changes in space. Gilroy explains, “There are literally thousands of experiments done on Earth [on Arabidopsis]. Cold shock. Touched them. Not watered them. Too much water. Shouted at them,” he says with a chuckle. “Those databases are all available to us.
Plant Stress and Defense Mechanisms
Some patterns that arise are expected, like when the genes associated with gravity become altered. The plants seem to have increased stress from oxidation. Normal chemistry in the cells makes a very reactive oxygen-based chemical. Uncontrolled, this “reactive oxygen species” can react with the machinery that repairs DNA and mess that up, or it can damage mitochondria. In a healthy plant, the cells have ways of dealing with it. The other pattern is certain genes associated with the immune system turn on and others switch off in space.
There is anecdotal evidence, too, that plants in space may be struggling to fend off pathogens. Once, the zinnias in Veggie got a little overwatered, and there was a lack of air flow. A fungus started growing on the plants, and some died. Astronaut Scott Kelly delicately cleaned off the fungus, nursed the surviving plants back to health and got them to flower.
Rather than intentionally making Veggie plants sick to test this theory, scientists want to run gene expression studies using BRIC-LED and trick plants into thinking they’re being threatened. Bacteria use a whip-like structure called a flagellum to help them swim, and flagella all share a common set of 22 amino acids nicknamed “flag-22.” Plants are looking for flag-22, and their defense systems kick on as soon as they pick up on it. Scientists can squirt a harmless solution of flag-22 onto the plants.
In the BRIC-LED experiment, tiny plants are grown for 10 days, and then scientists squirt them with flag-22. An hour later, the plants are fully defending themselves, and scientists douse them with a chemical fixative to stop all biological processes. This fixative does a great job of preserving the plants’ response state, but as an added step, the plants are put into a deep freeze. Gilroy hopes to learn more about the effects of space on a plant’s health this way.
Process Plants on Earth
A process plant is a large industrial facility designed to transform raw materials into valuable products through a series of chemical or mechanical processes. A process plant takes various raw materials, such as chemicals or natural resources, and refines or transforms them into finished goods or intermediate products. For instance, a chemical process plant may convert petroleum into plastics, or a food processing plant might turn raw ingredients into packaged food products.
Investing in used equipment for a process plant has significant advantages, including cost savings and faster installation timelines.
| System | Description | Purpose |
|---|---|---|
| Veggie | Small, carry-on sized plant growth system | Study plant growth in microgravity, supplement astronaut diet |
| APH | Enclosed, automated plant growth chamber | Advanced plant research with minimal crew involvement |
| BRIC | Facility for studying effects of space on small organisms | Gene expression studies, plant defense mechanisms |