ISS Science for Everyone
Science Objectives for Everyone
Organisms grow differently in space, from single-celled bacteria to plants and humans. But future long-duration space missions will require crew members to grow their own food, so understanding how plants respond to microgravity is an important step toward that goal. Veg-03 uses the Veggie plant growth facility to cultivate a type of cabbage, which is harvested in orbit with samples returned to Earth for testing.
Science Results for Everyone
The following content was provided by Gioia D. Massa, Howard G. Levine, Ph.D., and is maintained in a database by the ISS Program Science Office.
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Gioia D. Massa, Kennedy Space Center, Kennedy Space Center, FL, United States
Howard G. Levine, Ph.D., Kennedy Space Center, Cape Canaveral, FL, United States
NASA Kennedy Space Center, Cape Canaveral, FL, United States
Sponsoring Space Agency
National Aeronautics and Space Administration (NASA)
NASA Research Office - Space Life and Physical Sciences (NASA Research-SLPS)
Earth Benefits, Scientific Discovery, Space Exploration
ISS Expedition Duration
- February 2017
Veg-03 is a direct follow-on to the Veg-01 hardware validation test. The primary goal of the Veg-01 hardware validation test was to demonstrate plant growth in the Veggie facility. ‘Outredgeous’ red romaine lettuce plants were grown in two different sizes of arcillite, a calcined clay media. The completion of the first run of Veg-01 helped investigators compare root zones of two media sizes to determine water and root distribution within the different sized-particles to provide recommendations for future Veg series investigations. Shoot tissue samples provided information on the microbial load of the plants. Photographs taken during the first run helped in the assessment of plant growth rates, as well as plant health. Two data loggers recorded the temperature and relative humidity within the Veggie facility. Crew questionnaires provided insight into the appropriateness and thoroughness of the crew procedures for the Veggie facility and plant growth operations. Although plant pillows performed well, modifications are necessary for future watering procedures. Veg-03 tests the performance of the water delivery system with modified procedures, and a different crop with different water requirements than that of the ‘Outredgeous’ red romaine lettuce.
Plant pillows are single use items, thus reducing the chances of microbial contamination of the Veggie facility and produce. A major aspect of the Veg-01 hardware validation test was to collect baseline microbial data from plants and plant pillows grown in the Veggie facility on ISS. Ground testing has demonstrated very low microbial levels on lettuce plants grown in the ground Veggie facility. Preliminary flight tests conducted on the Veg-01 returned samples indicated fairly low microbial levels without specific pathogens. Discussions with space microbiologists, flight surgeons, and space food technologists indicated that the crew should be able to consume the fresh produce with precautionary sanitizing using on-orbit Prosan wipes since microbial levels in the returned samples were sufficiently low. Preparation is underway to formally document that concurrence. The baseline data collected from both the Veg-01 and Veg-03 flight experiments are a resource for future Veg series investigations. This information provides data on necessary procedural changes, hardware upgrades, or horticultural options, as Veggie becomes an integral part of ISS expeditions in the future.
The overall goal of Veg-03 is to further demonstrate proof-of concept for the Veggie plant growth chamber and the planting pillows. This research builds upon hardware development via a SBIR grant to ORBITEC for the initial prototype Veggie units with subsequent hardware development for next-generation units. Both ORBITEC and KSC have been involved in plant growth optimization of the Veggie hardware and testing and collaboration have resulted in the development of the pillow planting concept to interface with the Veggie hardware. Through numerous tests the VEG-03 science team has refined the pillow concept and selected growth media and fertilizers, plant species, materials, and protocols for using the pillow concept in Veggie to grow healthy plants that can provide crew with food and recreation. The pillow concept is designed to be low mass, modular, require no additional energy and be very low maintenance. Pillows of different sizes have been designed to accommodate a wide variety of plant types and different types of growing media.
The primary goal of the Veg-03 testing is to demonstrate plant growth in the Veggie hardware using 'Tokyo Bekana' cabbage as a test crop. Plants are grown in two different sizes of arcillite, a calcined clay media. This test helps investigators compare root zones of the two media sizes to determine water and root distribution in the different sized-particles to provide recommendations for future Veggie investigations. Shoot tissue samples also provide information on any growth anomalies when compared with ground controls. Photographs are used to assess plant growth rates and plant health. A data logger records the environment within the Veggie hardware. Crew questionnaires provide insight into the appropriateness and thoroughness of the crew procedures for Veggie hardware and plant growth operations.
Pillows are single use and thus reduce the chances of microbial contamination of the Veggie hardware and produce. A major aspect of the proof of concept flight, Veg-03, is to collect baseline microbial data from plants and pillows grown on ISS. Ground testing and Veg-01 results have demonstrated very low microbial levels on lettuce plants grown in Veggie-relevant conditions. Discussions with space microbiologists, flight surgeons, and space food technologists at the Johnson Space Center in Houston, TX indicate that if microbial levels are sufficiently low, the crew could consume the fresh produce without sanitizing. For crops that naturally have higher levels of microorganisms (e.g. radishes, which grow in contact with water and nutrients), a space-rated produce sanitation method must be developed and tested.
The baseline data collected from the Veg-03 flight serves as a resource for future Veggie investigations such as a recently awarded ILSRA grant flying on SpaceX-14. This information provides data on necessary procedural changes, hardware upgrades, or horticultural options.
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Future long-duration missions into the solar system, finally culminating on Mars, will require a fresh food supply to supplement crew diets, which means growing crops in space. Previous investigations focused on improving productivity in controlled environments, but the limited quarters of the space shuttle and International Space Station made it difficult to conduct large-scale crop production tests. Veg-03 expands on previous validation tests of the new Veggie hardware, which crew members will soon use to grow cabbage, lettuce and other fresh vegetables in space. Tests determine which types of microorganisms are present in space-grown cabbage, providing baseline data for future crop-growing efforts. Behavioral health surveys assess the impact of growing plants on crew morale and mood.
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Results from this investigation contribute to basic research on plant cultivation, benefiting agricultural and biomass production efforts on Earth. The technology used in the Veggie experimental hardware could be adapted for horticultural therapy for elderly or disabled individuals who would otherwise be unable to enjoy a garden.
Operational Requirements and Protocols
Veg-03 uses the on-orbit VEGGIE facility and requires water from the Potable Water Dispenser (PWD) and use of the Maintenance Work Area (MWA).
The Veggie facility is activated with the desired photoperiod, light levels, and fan speed programmed via the control panel. The Veggie Bellows Subassembly is removed from Veggie, and placed on a MWA. The Root Mat is then placed in the Veggie Bellows Subassembly. Six plant pillows are then unstowed, placed, and secured via elastic bands on the Root Mat in designated positions. The subassembly is reinstalled to the flex arms attached to the Veggie Lightcap. The watering syringe assembly is used to pull PWD water from the water bag and inject it into the plant pillow priming fitting to initially wet each plant pillow. After priming all the plant pillows, the Bellows Subassembly is attached to the Lightcap Subassembly, and PWD water from a water bag is used for the initial filling of the Root Mat reservoir. A 10 mL water sample is taken from the reservoir and stored in the Minus Eighty Degree Laboratory Freezer for ISS (MELFI) at -95°C. A crew member will take initial photos of the Veg-03 experiment setup.
The plants are checked regularly, and additional potable water from water bags is added as scheduled using the watering syringe assembly. Three days following initiation, wicks are separated to allow the plants to emerge. Plants are thinned to one plant per pillow after seven days. Scheduled photos of plant growth are taken and downlinked to the ground. A new harvest technique called cut-and-come-again will be utilized. This is a series of 3 smaller harvests and a final harvest. 1st harvest: Crew to harvest and eat approximately 2-3 of the larger lettuce leaves from each plant. Sanitize the leaves using the pro-san wipes we have provided. The remainder of the plant will be left to grow and sprout new leaves. 2nd harvest: approximately 7-10 days later. Crew will harvest between 1-2 leaves from each plant and preserve leaves in foil which will then be transferred to MELFI for science data. 3rd harvest: approximately 7-10 days later. This will be a repeat of the first harvest for crew consumption. Final photographs and microbial swab samples are collected from the plants, and the Veggie facility on the scheduled final harvest day. The crew will be allowed to consume half of the plants, with the other half being returned for science.
At the final harvest, the cabbage plants are cut at the interface of the plant pillow and plant samples are wrapped in foil sheets, placed in a re-sealable bag and stored for sample return in MELFI at -95°C. Video of harvest operations is desirable. Plant pillows E and F are sealed in re-sealable bags for sample return. Plant pillow, plant samples, and microbial swab samples (-95°C) should be placed in MELFI less than1 hour after collection. Remaining plant pillows should be disposed of by placing in plastic trash bags. A second 10 mL water sample is taken from the Root Mat reservoir, and stored in MELFI at -95°C. Excess water is removed from the Root Mat using the watering syringe assembly, and then discarded in the water bag. Disinfectant ProSan wipes are used to clean and sanitize the interior of the Veggie facility and then discarded. Crew members working Veg-03 respond to questions in the procedure on operations and suggest improvements. Question responses and photographs are sent to the Veggie team via downlink. Science samples, including the data logger is returned on the first available flight after harvest. Microbial samples, water samples, plant samples, and plant pillows are returned at -95°C in GLACIER/POLAR. Crew members actively participating in Veg-03 operations answer additional questions during the post-increment debrief.
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Decadal Survey Recommendations
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The Plant Pillows growing lettuce during the Veg-01 experiment. "Tokyo Bekana" cabbage is the test crop during Veg-03. Image courtesy of NASA.
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