Mass Transport in a Spaceflight Plant Growth Chamber A. Hoehn , J. Clawson, A.G. Heyenga, P. Scovazzo, K.S. Sterrett, L.S. Stodieck, P. Todd BioServe Space Technologies, University of Colorado M.H. Kliss NASA Ames Research Center SAE paper 98-1553 28th International Conference on Environmental Systems, ICES, July 12-16, 1998, Danvers, MA.
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Mass Transport in a Spaceflight Plant Growth Chamber · Mass Transport in a Spaceflight Plant Growth Chamber ... 25x30 cm2 0.075 m2 ... Water condensate pumped from humidity control
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Mass Transport in a Spaceflight Plant Growth Chamber
A. Hoehn, J. Clawson, A.G. Heyenga, P. Scovazzo, K.S. Sterrett, L.S. Stodieck, P. Todd
BioServe Space Technologies, University of ColoradoM.H. Kliss
NASA Ames Research Center
SAE paper 98-1553 28th International Conference on Environmental Systems, ICES, July 12-16, 1998, Danvers,
Light Intensity (fluorescent) ≈ 350 µmol⋅m-2⋅s-1 PARAir Temperature Range 18-25°CHumidity Range (dew point) 60-100% r.H.Chamber Air Volume 28.3 literUsable Growth Area, 25x30 cm2 0.075 m2
Max. Theoretical Dehumid. Rate 17.28 liter⋅day-1 H2OMax. Water Supply to Roots 17.28 liter⋅day-1 H2OChamber CO2 Range 250 – 3,000 ppmCabin Air max. Intake Rate 2 liter⋅min-1
Max. CO2 Supply Rate for 500ppm Target / 3,000 ppm externalCO2 Concentration
7.2 liter⋅day-1 CO2
(14 gram⋅day-1 CO2)
CO2
O2
Light
H2O
PressureTemperatureRelative Humidity
MixingCirculation
PGBA Performance Limits:
Sealed Plant Chamber Due to:• containment of hazardous samples.• orbiter environment not suitable for
reproducible scientific conditions.• water recycling.• plant performance measurements.
Temperature Profiles
STS-94: independent day / night setpoints:• day 25°C / night 22°C• 20 minutes (heat) / 60 minutes (cool) to reach new setpoint
Humidity Control
STS-94: dew point control limited by available power:• humidity controlled by dew point temperature only.• cooled porous plate maintained under suction to separate condensate.• condensate supplied to root re-hydration system.
Mission Temperature Profile
• Independent day/night temperature setpoint.• Temperature exceedance on return due to hot ambient temperatures.
Mission Humidity Profile
• flight vs. ground reasonably tracked.• ground control exceedance on day 9 due to flow controller failure.• elevated humidity on mission beginning / end due to elevated ambient temperatures.
Water Recovery from Air Humidity
Water condensate pumped from humidity control to nutrient delivery:•3,000 ml H2O in 17 days ~ 175 ml/day ≈ 2,350 ml m-2 day-1
Water Recovery from Air Humidity
3,000 ml H2O in 17 days ~ 175 ml/day ≈ 2,350 ml m-2 day-1
Atmosphere Composition
C 3 P lan t
Rat
e of
Pho
tosy
nthe
sis
L igh t In tensity
C om pensation P o in t20 -80 µm ol*m -2s -1 P A R