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The Magnetic Field Apparatus (MFA) was developed specifically to test whether high gradient magnetic fields (HGMFs) can simulate gravity by providing a directional stimulus for plants grown in space. This space shuttle middeck-locker experiment was designed to imbibe dry flax (Linum usitatissimum L.) seeds on orbit, capture time-lapsed images of the emerging roots as they are exposed to HGMFs, and, at the appropriate time, chemically fix the biological material. One of the major obstacles in the development of this payload system was to determine exactly when was the ‘appropriate’ time for fixation. Ideally the emerging roots were to be fixed after they have passed the area of highest magnetic gradient (∼8mm), but before they have grown so long as to physically touch the sides of the chamber (∼12mm). Initiating the fixative delivery sub-system within this relatively narrow window of acceptability was obtained with a unique iterative control methodology.

The use of Green Fluorescent Protein (GFP) as a reporter gene system is an accurate and non destructive means for generating organ, tissue and cell-specific data on gene expression in plants. While many commercial imagining systems are available for standard terrestrial laboratory imaging of GFP, none of these systems begin to meet the requirements for a flight unit that could be utilized to monitor plant gene expression in spaceflight habitats. We present here data derived from ground testing of a prototype GFP flight imaging unit, the TAGES Imaging System (TIS). The TIS software is designed to collect multiple images of the same view to facilitate the stacking of the images for enhanced detail resolution. Analyses of stacking software and tactics for improving resolution are being evaluated. The TIS is being developed as a component of the payload hardware design of the next generation of Plant Growth Facility (PGF).

The WONDER space flight experiment will compare the operation of both substrate-based and porous tube nutrient delivery systems (NDS) under microgravity conditions. Each NDS will be evaluated with three moisture availability regimes, and moisture sensing will be critical for the operation and evaluation of the systems. Orbital Technologies (Madison, WI) has developed a space flight-rated temperature and moisture acquisition system (TMAS) for measuring water content of plant growth medium. The sensors were evaluated in 0.25-1 mm and 1-2 mm baked ceramic aggregate (Profile and Turface, respectively). The sensors' pooled standard deviations ranged from approximately 2% to 5% relative water content (RWC), and root mean square error between sensor RWC and measured RWC was greater than 3% using linear calibration.