OpNom: PGBAExperiment Overview
Plant Generic Bioprocessing Apparatus (PGBA) monitored and maintained light, temperature, humidity and oxygen levels to study lignin production changes in Arabidopsis thaliana (a fast growing plant) grown in microgravity on the International Space Station (ISS).
PGBA is capable of maintaining the light, temperature, humidity and oxygen levels for a wide variety of plants. Several different types of plants have been grown inside PGBA, including wheat, tomatoes, loblolly pine, spinach, periwinkle, white clover, pepper, sage, and purple cone flower.
University of Colorado at Boulder, BioServe Space Technologies, Boulder, CO, United States
National Aeronautics and Space Administration (NASA)Sponsoring Organization
Human Exploration and Operations Mission Directorate (HEOMD)Research Benefits
Information PendingISS Expedition Duration
June 2002 - December 2002Expeditions Assigned
5Previous ISS Missions
PGBA flew previously as Astro Plant Generic Bioprocessing Apparatus on STS-77, STS-83, STS-94.
The Plant Generic Bioprocessing Apparatus (PGBA) is used to grow and monitor plants in microgravity experiments. PGBA is a self-contained plant growth chamber that provides preset or remotely controlled temperature, humidity, nutrient delivery, and light. The PGBA venting system supplies the plants with ambient air and controls ethylene buildup.
The objective of the PGBA during Expedition 5 was to grow two crops of Arabidopsis thaliana (thale cress). The first crop was to be harvested when it reached maturity and placed into cold storage in the Commercial Generic Bioprocessing Apparatus (CGBA). The second crop was to be started after the harvest of the first crop and returned to Earth while it was still growing. Scientific objectives were focused on understanding lignin production. The PGBA investigation was to examine changes in plant lignification (to become woody through the formation and deposit of lignin in cell walls) and related downstream biochemical consequences, especially production of secondary metabolites.
The PGBA is equivalent to two middeck lockers in volume 0.028 m3, weighs 4 kg, and uses 230 W of power.
Data acquisition for PGBA includes plant growth data through video and plant performance data. All sensor data are recorded by the PGBA Data Acquisition and Control Computer while an internal video camera provides video images that can be recorded or downlinked to Earth in near real time. PGBA can also test plant performance in the possible support of edible biomass in space and, in the more general use, as a component in advanced life support.
PGBA maintains a nutrient delivery system for plants and has a 6.35 cm rooting depth and 25 cm x 30 cm x 25 cm aerial tissue volume. PGBA can support up to 120 plants and provides temperature, humidity, carbon dioxide, and lighting control.
The ability to grow plants in space will have an enormous impact on the success of future interplanetary space exploration. Any long-term human presence on the Moon or Mars will require sustainable plant growth, which can provide a renewable food supply for explorers and assist with the maintenance of breathable air.Earth Applications
One interest to scientists and industry is the structural compound called lignin which is produced by plants. Lignin is one of the molecules plants use to make stiff, woody cell walls. Plants grown in space produce less lignin because in the absence of gravity they don't need such a woody structure. Genetic information gained from plants grown in the PGBA could enable scientists on Earth to control the amount of lignin a plant produces. Growing trees with less lignin could dramatically reduce the economic and environmental cost of paper production, allowing faster tree growth, more paper production, and less chemical use during milling. Other plants could gain added protection from the elements if lignin production was increased.
PGBA operates on 150 watts of continuous power, provided by an EXpedite the PRocessing of Experiments to Space Station (EXPRESS) Rack, but can withstand up to an 8-hour power outage without negatively affecting the plants within.Operational Protocols
PGBA is installed for launch 16 to 33 hours before launch. PGBA is fully automated, including video and still imagery capabilities. External heat rejection is accomplished through forced convective cooling with cabin air. All control interfaces are on the front panel. PGBA does not have to be opened on orbit for operations.
During ISS Expedition 5, PGBA was to grow two crops of Arabidopsis thaliana, a fast-growing plant often used for on-orbit research. Harvested PGBA samples were to be stored in the CGBA until return to Earth for analysis by investigators. The investigators were to analyze the preserved samples and the returned plants, looking for structural and chemical changes caused by the microgravity environment.
The returned plant material did not develop in a normal manner, and the primary scientific objectives were not met. The study did, however, help identify the need for greater regulation of air quality within a plant growth chamber to ensure uniform plant growth. Although there will be no results published from this ISS activity, the lessons learned from this study are being applied to the development of subsequent plant growth investigations and improved space flight plant chamber design (Heyenga et al., 2005). (Evans et al. 2009)
Heyenga AG, Hoehn A, Kliss M, Stodieck LS, Blackford C. Approaches in the Design of a Space Plant Cultivation Facility for Arabidopsis thaliana. 34th International Conference On Environmental Systems, Colorado, Springs, CO; 2004 [New designs influenced by lessons learned]
Heyenga AG, Kliss M, Blackford C. The Performance of a Miniature Plant Cultivation System Designed for Space Flight Application. 35th International Conference on Environmental Systems, Rome, Italy; 2005 July [New designs influenced by lessons learned.]