Pick-and-eat space crop production flight testing on the International Space Station

ABSTRACT

Fresh, nutritious, palatable produce for crew consumption on long-duration spaceflight missions may provide health-promoting, bioavailable nutrients and enhance the dietary experience. VEG-04A and VEG-04B explored growing leafy greens on the International Space Station using the Veggie Vegetable Production System. Two flight tests with ground controls were conducted in 2019 growing mizuna mustard, where Veggie chambers were set to different red-to-blue-to-green light formulations. Light quality affects plant growth, nutrition, microbiology, and organoleptic characteristics on Earth, and we examined how these vary in microgravity and under different harvest scenarios. Astronauts harvested and weighed mizuna and completed organoleptic evaluations. Flight samples were returned to Earth for nutritional quality and microbial food safety analyses. Yield and chemistry differed between ground and flight samples and light treatments, and bacterial and fungal counts were lower in ground than in flight samples. This research helps increase our understanding of the requirements for growing high-quality crops in spaceflight.

Policy highlights

• The Veggie system can provide astronauts with nutritious, safe-to-eat produce that they enjoy eating, which can help crews stay healthy during long-duration space missions.

• The duration and method of growing and harvesting crops can influence the yield, organoleptic acceptability, microbial load and food safety, nutritional content, and resources required. A decision on optimum methods will likely involve trade-offs and needs to be weighed against mission objectives.

• The light spectrum used to grow plants impacts the growth and nutritional content of leafy green crops.

• Continued research in this area is recommended to test additional crops and to increase research sample sizes.

KEYWORDS:

• Food safety
• International Space Station
• nutrition
• plant growth
• space-crop production
• Veggie

Acknowledgements

Spaceflight research could not be performed without a team, and our Veggie research has a dedicated and passionate team. We are very grateful for the efforts of our Veggie Project Manager for VEG-04, Trent Smith, and of the support from members of KSC’s Test Operations and Support Contract (TOSC), especially John ‘JC’ Carver and Chuck Spern; KSC’s Laboratory Support Services and Operations (LASSO) Contract; Marshall Space Flight Center’s Payload Operations and Integration Center (POIC); and JSC’s Research Operations and Integration (ROI) Office, especially Peggy Delaney and Jaime Valverde. We would like to acknowledge the support of our collaborator, Florikan ESA, and especially the support of Florikan Founder and Chairman Ed Rosenthal, in helping to make decisions about the types and rates of fertilizer to use, and for supplying the fertilizer for this testing. We are grateful for the help of numerous undergraduate and graduate student interns at NASA and Sierra Space, and student researchers at Purdue University who helped to support this research. Former NASA postdoctoral fellows Matthew Mickens, Christina Johnson, and Lucie Poulet were helpful in the development or execution of this research. We would like to recognize Takiyah Sirmons and the JSC Space Food Systems Laboratory for running the organoleptic evaluations, and we appreciate all the volunteer testers. An awesome team of scientists was involved in obtaining the sample results, including Christina Khodadad, Carolina Franco, Jen Gooden, and Gretchen Maldonado Vázquez. Finally, these plant experiments could not have been completed without the dedicated work and feedback of the astronauts from ISS Expeditions 59, 60, and 61, and we would like to thank the ISS Program, NASA Space Biology, and NASA’s Human Research Program for their support.

Author contributions

All authors contributed to the design of the work with JB, MH, LS, and MY completing research and data analysis. All authors contributed to the development of the manuscript and final version to be published.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This research was co-funded by the NASA’s Human Research Program and NASA Space Biology (MTL#1075) through the ILSRA 2015 NRA call.

Notes on contributors

Jess M. Bunchek

Jess Bunchek is a botanist (B.S., Purdue University), agronomist (M.S., The Pennsylvania State University), and current PhD candidate in space systems engineering at the University of Bremen (Germany) and the German Aerospace Center (DLR) Institute of Space Systems. While at NASA’s Kennedy Space Center, she supported space crop production on the International Space Station, primarily with the Veggie plant growth chambers. From late 2020 to early 2022, Jess overwintered in Antarctica at Neumayer Station III as the EDEN ISS greenhouse operator, a collaboration between DLR, NASA, and the Alfred Wegener Institute–Helmholtz Center for Polar & Marine Research.

Mary E. Hummerick

Mary Hummerick is lead microbiologist (MS, University of South Florida) currently working under the LASSO II contract at NASA's Kennedy Space Center. She has led the effort to define the microbiological food safety aspects of food crops grown on the International Space Station and in control environment chamber studies at KSC focusing on the microbiome of space-grown crops. She has been a co-investigator and contributor to several ISS plant growth experiments and technological demonstrations. Her other research interests include disinfection and biofilm prevention technologies and biological waste and water processing for bioregenerative life support systems.

LaShelle E. Spencer

LaShelle Spencer is a scientist with the Laboratory Support Services II Contract (LASSO II) at the Kennedy Space Center (KSC). She serves as Lead Horticulturist, supporting Space Crop Production research. She received her B.S. in Horticulture and M.S. in Plant and Soil Science from Tuskegee University. Prior to joining the LASSO team, she conducted extensive research on hydroponic plant growth systems for space research at Tuskegee University. Following this, she served with the Ground Research team on the Life Science Services Contract at KSC, further supporting hydroponic plant research. She later honed her skills in analytical chemistry, micro and molecular biology by participating in over a dozen bioregenerative life support themed projects, which included plants, water, and waste recycling. She has been co-investigator for several spaceflight experiments including the PH-04 chile (chili) pepper study on the International Space Station (ISS). This was the longest, most complex plant growth study to date on the ISS.

Matthew W. Romeyn

Matthew Romeyn was a plant ecologist/molecular biologist at NASA’s Kennedy Space Center (KSC). Matt was responsible for technology demonstration studies with the Veggie plant chamber on the International Space Station (ISS) and oversaw operations for KSC’s controlled environment research laboratory. His research focused on microgreens as a candidate food crop, plant microbiome studies, and he served as NASA’s lead for the PH-04 study with chile (chili) peppers grown in NASA’s Advanced Plant Habitat on the ISS. This was the longest plant experiment ever conducted in space. He was passionate about the development and implementation of a crop readiness plan and on-orbit gardening handbook with the goal that in the future, crews will be able to select and independently grow plants of their choosing while in space. Tragically, Matt died in an auto accident in 2022. He will always be missed by his many colleagues and friends at KSC and the space biology community.

Millennia Young

Dr. Millennia Young, Ph.D. is the Lab Lead of the Biostatistics and Data Science Lab at NASA’s Johnson Space Center. Dr. Young has spent the last 10 years providing statistical support to both research and medical operations, working with human health and performance data. This has provided her with substantial experience in NASA-specific statistical complexities including very small samples sizes, unbalanced designs, and missing data.

Robert C. Morrow

Dr. Robert Morrow has over 40 years of research and development experience related to biomass production for space-based bioregenerative life support systems, including 33 years of experience in the development of hardware for space-based plant growth facilities. That work included development of environmental control subsystems for nutrient delivery, humidity control, and LED lighting subsystems currently being flown on ISS. He has been involved in the development of 9 plant growth systems flown in space to date, and his current activities involve design, development, and flight testing of aeroponic/hydroponic technologies for scaled-up crop production systems for microgravity. Dr. Morrow has PhDs in Horticulture and Botany from the University of Wisconsin–Madison and is a Principal Scientist at Sierra Space in Madison, WI.

Cary A. Mitchell

Dr. Cary Mitchell is Professor of Controlled Environment Agriculture at Purdue University. He was in the first group of investigators for the following NASA Programs: Space Biology, Controlled Ecological Life Support Systems, and Advanced Life Support Systems. Recent efforts emphasize leveraging unique properties of light-emitting diodes to significantly reduce energy expenditure for crop lighting in space and for commercial indoor agriculture.

Grace L. Douglas

Dr. Grace Douglas serves as the lead scientist for NASA’s Advanced Food Technology research effort at the Johnson Space Center (JSC), which focuses on determining methods, technologies, and requirements for developing a safe, nutritious, and palatable food system that will promote astronaut health during long-duration space missions. Her responsibilities include assessing the risk of an inadequate food system to crew based on vehicle designs and mission concepts, and developing the research path that will ensure the food system meets crew health requirements on spaceflight vehicles. She is principal investigator for NASA’s Crew Health and Performance Exploration Analog (CHAPEA) at JSC. She earned a B.S. and M.S. in food science from The Pennsylvania State University and North Carolina State University, respectively, and a Ph.D. in functional genomics from North Carolina State University.

Raymond M. Wheeler

Dr. Raymond Wheeler is a plant physiologist and senior scientist at NASA’s Kennedy Space Center, where he has led the Advanced Life Support research group. This includes controlled environment studies with crops for food and oxygen production, CO₂ removal, and wastewater processing. Over the years, Ray has studied plant responses to gravity, CO₂, light, atmospheric pressure, and hydroponic crop cultivation. Ray has been co-investigator for several spaceflight experiments, including the first test to demonstrate potato tuber development in space, and studies using the Veggie and Advanced Plant Habitat growth chamber on the International Space Station to growth fresh vegetables for the astronauts.

Gioia D. Massa

Dr. Gioia Massa is a plant scientist at NASA’s Kennedy Space Center (KSC) working on space crop production for the International Space Station (ISS) and future exploration missions. She holds a B.S. in Plant Science from Cornell University and a Ph.D. in Plant Biology from The Pennsylvania State University. Prior to joining NASA, she worked as a postdoctoral fellow at Purdue University and as a research fellow in the NASA Postdoctoral Program (NPP) at KSC, conducting research on crops for bioregenerative life support. She has studied a range of crops for future food production in space, focusing on their horticultural and environmental requirements, including responses to light spectral quality using light emitting diodes (LEDs). She led the science team for initial testing and validation of the Veggie plant growth chamber on the ISS and has conducted comparative studies with leafy greens and tomatoes on the ISS. Her other research interests include nutrition, flavor, food safety, and the psychological benefits of space-grown crops. Throughout her career, Gioia has been an avid supporter of student outreach.