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APPARATUS TO MONITOR AND CONTROL VOLATILE ORGANIC COMPOUNDS EFFECT ON PLANT GROWTH AND DEVELOPMENT.  I. Eraso, G.W. Stutte and S.M. Anderson.  Dynamac Corp., Mail Code DYN-3, Kennedy Space Center, FL.

   The growth of higher plants in microgravity will require an understanding of how plants respond to specific environmental stresses of the spacecraft.   Manned spacecraft are designed to have extremely low leak-rates that contribute to the accumulation of trace gas contaminants in the atmosphere.  These volatile organic compounds (VOC) may originate from both biogenic (plants, animals, micro-organisms) and anthogenic (materials, experiments, equipment).   NASA has established standards (Spacecraft Maximum Allowable Concentrations, SMAC) for astronaut exposure to selected airborne contaminants.   The effects of chronic exposure of atmospheric contaminants on plant growth and development are less well known.  Existing semi-closed Lexan chambers (38 x 35 x 30 cm) that have CO_2, temperature and relative humidity control were modified to provide controlled exposure to selected VOC’s.  A 16-port multisampling valve is connected to a SRI-8610C Gas Chromatograph (SRI Instruments, Torrance, CA) to provide closed loop sampling and control from impingers containing the VOC of interest to three exposure chambers.   Sampling rates and VOC additions are controlled and monitored by custom software developed within LabView 6.1 (National Instruments).  VOC are quantified using PeakSimple^TM software.  Experiments have been initiated to screen biological sensitivity of Raphanus sativus L. cvs. to the most common ISS atmospheric contaminants.  Typical biological screening is performed at 1x and 0.1x the NASA SMAC level for chronic exposure to a selected contaminant. 

(This research was supported by grant from NASA OBPR Fundamental Biology Programs (NCC10-0034))