The preliminary results are in: plants in space appear to grow and develop normally! Wisconsin Center for Space Automation and Robotics (WCSAR) Plant-Space Biologist Dr. Bratislav Stankovic finds this extremely exciting and thinks the rest of us should as well.

Dr. Stankovic and one of WCSAR’s growth chambers.

WCSAR is a research center affiliated with the UW-Madison College of Engineering and funded primarily by NASA. At WCSAR, the study of plants in space has two objectives: first, to determine how to grow plants in microgravity and second, to determine how those plants grow and develop. Stankovic and others at WCSAR recently completed preliminary analysis of the first complete life-cycle plant growth experiment onboard the International Space Station (ISS).

The experiment consisted of growing the Arabidopsis thaliana from seed to seed over a period of two months. Arabidopsis thaliana is a relatively simple plant used as model system for plant molecular biology studies. What makes this experiment so exciting, according to Stankovic, is the healthy, normal growth observed and the intriguing implications of these results. "We are right now scratching the surface of understanding how to grow plants in microgravity and what, if anything, is different in microgravity."

Unfortunately, environmental control problems have rendered much of the previous research regarding plant growth and development useless to science. The main source of contamination in past experiments was the presence of ethylene, a plant hormone capable of causing sterilization when present in excess. The Arabidopsis experiment used the innovative environmental control systems of the Advanced Astroculture growth chamber, developed by WCSAR engineers, to remove these contaminations.

Advanced Astroculture, about the size of a shoebox, contains an ethylene scrubbing device designed to maintain low ethylene levels, much like a carbon dioxide scrubber does for a spaceship. The scrubber works by oxidizing the ethylene hydrocarbons to CO2 and H2O. Advanced Astroculture also incorporates a seed tray which uses a unique grid-like restraining system to hold seeds, nutrients and soil firmly in place.

Without the complicating presence of ethylene, Stankovic had the unprecedented opportunity to examine Arabidopsis plants against those grown in an identical chamber on Earth. Upon analysis, researchers noted almost no differences between those plants grown in space and those in the control environment on Earth. This preliminary analysis only considered physically observable characteristics, from seed production and viability to plant mass.

Presently Stankovic and his associates are working on the secondary analysis. He explains, "We are trying to understand what happens to plants on a molecular level in microgravity, how similar or dissimilar they are to plants we grew on the ground in the identical growth chamber." A process called gene expression profiling was used to allow researchers to see exactly what happens on a molecular level. Genetic messenger molecules are tagged with a fluorescent substance that glows only when these messenger molecules are released, signaling an active gene. In this way it is possible to see exactly which genes in each cell are active.

Stankovic hopes to complete the analysis and publish this unprecedented and highly anticipated research towards the end of 2003. Once published, it will represent the first comprehensive report of plant gene expression profiling under the influence of microgravity.

"In the year 2003 we are still in the heroic age of understanding how plants and other organisms grow and develop in microgravity." Stankovic sees the Arabidopsis experiment as the beginning of many sustained plant growth experiments onboard the ISS. The Arabidopsis experiment suggests that plants can and do grow and develop normally under tightly controlled conditions. This has enormous implications for the future of space travel as well as possible commercial applications. "No matter what result we get from this gene expression data, it will be interesting. If they are similar we don't need to worry about growing plants on Mars. If they are different we had better find out how different they are, and use genetic engineering to mitigate any undesirable effects of microgravity," Stankovic notes.

If shown empirically to be unaffected by microgravity, presumably plants will be unaffected by any amount gravity in the range of 0 to 1g. This opens the possibility of plants growing elsewhere, from the Moon to Mars and beyond. According to Stankovic, NASA is currently looking at Mars-deployable greenhouses for future missions to Mars. Such greenhouses will only be possible if research at WCSAR and other research centers like it shows plants to have normal life cycles even at a molecular level in microgravity environments.

Extended space travel requires some sort of renewable food source, which plants can provide if they can be grown successfully in microgravity. To be renewable, plants also must be able to reproduce viably. If this can be done, a major obstacle to space travel will have been eliminated. Plant-space biologists like Stankovic have determined 12 plant species useful for life support applications in space. These species include lettuce, tomatoes, spinach, carrots, peppers, strawberries and fresh herbs such as chives, basil, mint and dill. Stankovic hopes to begin research with some of these species once the simpler Arabidopsis plants have been fully studied. With successful completion of this research, astronauts will be able to enjoy vegetables grown in future versions of WCSAR's Advanced Astroculture growth chambers.

The psychological benefit of such research cannot be neglected, especially in the wake of the Columbia tragedy. The Columbia was carrying two WCSAR experiments back to Earth. Stankovic considers the opportunity to work with the astronauts who conduct his experiments to be one of the perks of his job.

Research continues despite the tragedy, though it will be a while before the next WCSAR experiment will head for the stars. According to Dr. Stankovic, research must continue, because "only now are we in a position to address fundamental environmental and biological questions."