Search Results

The PESTO (Photosynthesis Experiment and System Testing and Operation) spaceflight experiment is designed to directly measure gas exchange of developing stands of wheat (Triticum aestivum L.) on the International Space Station (ISS). Gas exchange measurements will characterize photosynthesis and transpiration in microgravity at different stages of development. The Biomass Production System (BPS), a double middeck-sized plant growth will be the plant growth hardware used to support this experiment on-board ISS. This report presents results from a 10-day functional test of PESTO protocols in the BPS. Wheat canopy CO2 assimilation rate for 14-24 day-old plants grown in the BPS chambers was 6-7 μmol m-2 s-1 during this test. Plant responses to CO2 and photosynthetic photon flux (PPF) response curves were obtained at different stages of development by altering CO2 and light conditions.

Procedures were developed for a future experiment to measure wheat (Triticum aestivum L.) photosynthesis in microgravity. Specific attention was given to growing and maintaining vigorous wheat plants relative to the challenging conditions predicted in microgravity. These ground-based tests included comparisons of different rooting media, media, wicking materials, and nutrient delivery system pressures. To facilitate seed germination in microgravity, several clinostat tests were conducted to characterize the importance of initial seed orientation. Following establishment of a vigorous crop canopy, photosynthesis rates were measured and found to be affected by mutual plant shading within the growth chambers.

The Plant Growth Facility (PGF) is under development as a Shuttle middeck apparatus to support research on higher plants in microgravity. It is designed to operate for 15 days, and will provide (1) fluorescent lighting at a minimum of 220 μmol m-2 s-1 evenly distributed (±10%) over the growth area, (2) temperature control to a set point of ±10°C of cabin ambient with a control accuracy of ±1°C, (3) humidity control ±5% for set points between 30-80% RH, and (4) carbon dioxide control ±5% over a range of 300-5000 ppm. Filters will be provided to remove ethylene and trace organics from the internal air flow.

The Space Life Sciences Projects Office at NASA Ames Research Center (ARC), is responsible for developing and integrating nonhuman experiments flown aboard the Spacelab. Recent projects included hardware for experiments flown on the First International Microgravity Laboratory (IML-1) January 22-30, 1992. Two hardware projects are described. The Gravitational Plant Physiology Facility (GPPF) is a double rack piece of Life Sciences Laboratory Equipment (LSLE) designed to support plant growth studies under controlled conditions of g acceleration in the microgravity of space, with emphasis on gravitropic, phototropic, and circumnutational studies. The GPPF was designed by Principal Investigators at the University Science Center, and University of Pennsylvania, in Philadelphia, and flown by ARC, Moffett Field, California.