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Hypobaric Chambers for Biological Life Support Research

Hypobaric Chambers for Biological Life Support Research. Michael Stasiak, Cara Ann Wehkamp, Jamie Lawson, and Michael Dixon Controlled Environment Systems Research Facility Department of Environmental Biology University of Guelph. Pure H 2 O. CO 2. O 2. Edible Biomass. Inedible

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Hypobaric Chambers for Biological Life Support Research

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  1. Hypobaric Chambers for Biological Life Support Research Michael Stasiak, Cara Ann Wehkamp, Jamie Lawson, and Michael Dixon Controlled Environment Systems Research Facility Department of Environmental Biology University of Guelph

  2. Pure H2O CO2 O2 Edible Biomass Inedible Biomass Processed Waste Gray H2O Bioregenerative Life Support Systems • Edible Biomass Production • Carbon Dioxide Absorption • Oxygen Generation • Water Recycling • Waste Degradation

  3. Plant Growth Structure on Mars Two options exist: • Earth atmospheric pressure - heavy and opaque • Reduced atmospheric pressure - light-weight and transparent material

  4. Martian Atmosphere (0.6 kPa) 10 kPa 100 kPa Plant Growth Structure Benefits of Low Atmospheric Pressure • Need to minimize the pressure differential between the growth structure and the Martian atmosphere - simplifies the engineering requirements of the structure - decreases atmospheric leakage - reduces the amount of supplemental gas required for startup - ability to modify plant growth rates

  5. Summary • Mars is the best candidate for human exploration • Low pressure conditions may be advantageous to Martian habitation • Further investigation is required for the development of an atmospheric composition that allows for reduced pressure plant growth without compromising the plant production yields required for human life support

  6. Hypobaric chambers: design and function • Chamber design • Data acquisition and control • Temperature and humidity • Pressure • Carbon dioxide and oxygen • Lighting • Nutrient delivery

  7. Hypobaric chamber design • Five full canopy plant growth chambers • 1.0 x 1.8 x 2.5 m (WHD) • 4500 litre volume • Growing area of 1.5 m2 • Highly closed systems with low leakage • Internal surfaces 316 stainless steel • 20.5 mm laminate glass roof panels • Viton sealing rings on doors and glass • Fully automated • Capable of maintaining low pressures

  8. Lighting System Canopy Blower Cooling Coil Vacuum DOOR Nitrogen Blower Heater Condenser CO2 Oxygen 1.5 m Gas Sampling 1.8 m Internal Reservoir 2.5 m External Hydroponics Reservoir

  9. Data acquisition and control • Argus Control Systems Inc. • Distributed real-time control • Stand-alone microcontroller (Motorola 68HC811) on each chamber • Proprietary RS 485 communications network • Each hypobaric chamber operates independently • All sensor readings sampled once per second • Experimental data recorded once per minute (higher speeds available) • Operator interface provided through a PC-based system access and management program (Argus for Windows) • PC component is not used for real time control - failure of the PC has no consequence on system control

  10. Temperature and humidity • Variable speed blower • Blower speed control coupled to pressure • Chilled water (4°C) and hot water (55°C) heat exchange coils • Cold exchange coil controlled to achieve required VPD setpoint • Hot exchange coil used to reheat cooled air to regulate final temperature setpoint • Two Honeywell 4139 T/RH sensors • Four Argus TN2 temperature sensors (2 soil, 2 heat exchange) • Tipping bucket for evapotranspiration measurement

  11. Temperature: Radish Temperature (°C) Days after closure

  12. Vapour pressure deficit: Radish VPD (mb) Days after closure

  13. Relative humidity: Radish %RH Days after closure

  14. Evapotranspiration: Radish 18 DAP H2O Accumulation (litres) Hours

  15. Pressure • Vacuum pump: Busch Vacuum • Pressure sensors: Pribusin Inc • Control Valve: Swagelok • Control range +/- 0.1 kPa • Pressure control ambient to 0.01 kPa • Systems not designed for pressurization • Leakage rate less than 1% per day

  16. System leakage 66 kPa kPa 33 kPa Hours

  17. System leakage 10 kPa kPa 5 kPa Hours

  18. Pressure: Radish kPa Days after closure

  19. Carbon dioxide and oxygen • CO2/O2 analyzer: California Analytical Instruments Inc. Model 200 • NDIR CO2 and paramagnetic O2 sensors • One analyzer per chamber • CO2: 0 – 6000 µmol mol-1 (+/- 15 from set point) • O2: 0 -100%

  20. CO2 O2 N2 NC 1 NC 2 NC 3 Pressure regulator/gauge Hypobaric Chamber Pump • CO2/O2 sampling system based on repressurization of hypobaric chamber air • Chamber air continuously removed by a vacuum pump (KNF Neuberger Inc) • Air is repressurized in a sampling loop controlled by a non-bleed precision pressure regulator (Parker) and needle valve (HAM-LET) • Pressure gauge (Noshok) used to monitor and manually set the sampling stream to 0.2 psi Cold trap CO2/O2 Analyzer NV 1 Cold trap NV 2 Condensate return

  21. Carbon dioxide: Radish 18 DAP µmol mol-1 mmol accumulated Hours

  22. Oxygen: Radish 18 DAP Percent oxygen Hours

  23. Lighting • six 1000 watt HPS lamps (P.L. Light Systems) per chamber • Maximum irradiation intensity at highest bench level approximately 1500 μmol m-2 s-1 PAR • Externally mounted lighting canopy cooled with chilled water heat exchanger coupled to a blower • Two LiCor PAR sensors continuously monitor irradiation • lighting schedule automated and under control of the Argus Control System.

  24. Pressure compensation Chamber interior Legend: • Electrical Conductivity (EC) • Temperature (T) • Flow Meter (FM) • Normally Closed Valve (NC) • Tipping Bucket (TB) • Gravity Return (GR) • Proportional Valve (PV) Condenser PV1 TB EC1 T1 EC2 T2 Pump pH1 pH2 External Reservoir Nutrient delivery Internal Reservoir GR • NFT design • 400 litre temperature controlled external stainless steel reservoir • Circulation pump (International Pump Technology Inc.) provides sufficient pressure for chamber delivery from ambient to 2 kPa • Gravity return of water • Electrical conductivity (2 - Argus Control Systems, Inc) • pH sensors (2 - Honeywell Inc.) currently non-functional – pH is manually adjusted daily • Gravity feed of acid, base, and nutrient solutions NC1 NC2 NC3 NC4 FM FM FM FM Nutrient B BASE Nutrient A ACID

  25. EC: Radish Electrical conductivity (mS) Days after planting

  26. Nutrient delivery • Removable tray system • Pump truck to move crop to harvest lab • Quick-connect couplings for water delivery • Gravity return to external tank

  27. Acknowledgements

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