ShuttleEnvironmental/Thermal Control& Life Support SystemW. Guy• Cabin Atmospheric Revitalization Subsystem• Cabin Atmospheric Pressure and CompositionControl Subsystem• Water and Waste Management Subsystem• Cabin Thermal Control Subsystem• Spacecraft Active Thermal Control Subsystem• EVA Airlock Support SubsystemShuttle OrbiterEnvironmental/Thermal Control & Life Support SystemShuttle OrbiterEnvironmental/Thermal Control & Life Support SystemSubsystem Elements:• CABIN ATMOSPHERIC REVITALIZATION• CO2 and trace gas removal• Humidity control• Environmental cooling• Atmospheric circulation/ventilationCabin Atmospheric Revitalization_______________________________CO2 and Trace Gas Removal:• CO2 Acceptable level = 7.6 mmHg• CO2 Absorption (from humidified cabin gas)• Absorbent: Lithium Hydroxide (LiOH)• LiOH + CO2 LiCO3 + H2O + heat• Single use (expendable) <Cabin Atmospheric RevitalizationCO2 and Trace Gas Removal:• CO2 Absorption (from humidified cabin gas)• Absorbent: solid amine (polymerized ethyleneimine: RNH)• Absorb RNH + H2O RNH+2 + OH- OH- + CO2 HCO-3 + heat• Desorb RNH+2 + HCO-3+ heat + vacuum RNH + H2O + CO2• Multi-use (regenerative)Cabin Atmospheric RevitalizationCO2 and Trace Gas Removal:• Trace gas removal -• Activated charcoal• Single use (expendable)Environmental Cooling and Humidity Control:• Cabin atmospheric heat-exchanger• Condensing heat-exchanger• Centrifugal water/gas separatorCabin Atmospheric RevitalizationAtmospheric Circulation/Ventilation:• Redundant cabin fans• Flight-deck and mid-deck duct systemShuttle OrbiterEnvironmental/Thermal Control & Life Support SystemSubsystem Elements:• CABIN ATMOSPHERIC PRESSURE & COMPOSITION CONTROL• 14.7 psia total pressure control (normal)• 8 psia total pressure control (emergency de-orbit)• O2/N2 partial pressure control• Crew O2 breathing masks• Positive and negative cabin pressure relief (anomaly)• Gaseous O2/N2 storage• Pressurization N2 for Water & Waste ManagementCabin Atmospheric Pressure & Composition Control Normal Operations:• Total pressure control (gaseous N2)• 14.7 psia (“automatic” pressure regulator)• O2 partial pressure control (cryogenic O2)• 3.2 psia (“on-off” solenoid valve)Cabin Atmospheric Pressure & Composition ControlCabin Pressure Relief:• Over pressure protection – 16.2 psid - 3 relief values (only two needed)• Negative pressure protection – 8 psid - 3 relief values (only two needed)Cabin Atmospheric Pressure & Composition Control Crew Emergency Breathing Equipment:• Plug-in face masks• Purge-type breathing masks• For use with a contaminated cabin atmosphere• For use with a low concentration of O2 in cabinCabin Atmospheric Pressure & Composition Control• Shuttle spacesuits operate on 100% O2• Normally, ~four hours of 100% O2 pre-breath @ 14.7 psiarequired to prevent “bends”• However, subsequent to 12 hours acclimatization at 9 psia,only a short pre-breath required• The short pre-breath (~ 30 minutes) is accommodated bysuit-up and EVA preparation procedures• But cabin atmospheric pressure and composition controlnot designed for automatically maintaining 9 psia• Thus, a manual operational procedure for the crew wasrequired>9 psia Cabin Pressure Control for Pre EVACabin Atmospheric Pressure & Composition Control_____________________________________________Issues with 9 psia Cabin Pressure Operation• Flow-rate acceptability of fans at 9 psia• Thermal acceptability of fans at 9 psia• CO2 absorption performance of LiOH at 9 psia• Cabin ventilation adequacy for O2/N2 mixingwith press/depress operationShuttle OrbiterEnvironmental/Thermal Control & Life Support SystemSubsystem Elements:• WATER & WASTE MANAGEMENT• Potable/waste water inventory management• Potable water storage for drinking and food preparation• Waste water storage for dumping to space• Commode and urinal for human waste collection• Supply water for flash evaporatorsWater & Waste ManagementWater Sources:Potable Water• Fuel cell byproduct H2O• Launch storage of H2O• Drinking water sterilizationWaste Water• Condensate from cabin humidity control• Urine• Urine pre-treat for NH3Water and Waste ManagementSolid Waste:• On-orbit trash storage (overboard dump for odor control)• Human solid waste collection and storage (vacuum dried/stabilized)Shuttle OrbiterEnvironmental/Thermal Control & Life Support SystemSubsystem Elements:• CABIN THERMAL CONTROL• Cabin circulating liquid cooling system• Atmospheric heat sink• Cabin heat rejection to spacecraft cooling system• Avionics cold-plate heat rejection• Air-cooled avionics-bay heat rejection• EVA crew cooling in airlock• Crew potable water chillerCabin Thermal Control SystemCabin Thermal Control Subsystem Functions:• Cool cabin atmospheric• Cool atmosphere in avionics bays• Remove heat from cold-plated electronics• Cool IMU• Thermal control of windows & hatch• Provide water chiller for crew• Cool space-suited crew in airlock• Reject cabin thermal energy to vehicle heatrejection systemCabin Thermal Control SystemCabin Circulating Liquid Cooling Loop:• H20 as coolant• Redundant pumps• Liquid/gas heat-exchangers for atmospheric cooling• Cold-plates for electronics cooling• Window-mount/hatch-mount thermal controlAvionics Circulating Gas Cooling Loop:• Cabin atmospheric used as coolant• Redundant fans in avionics bays• Double redundant fans for IMU coolingShuttle OrbiterEnvironmental/Thermal Control & Life Support SystemSubsystem Elements:• SPACECRAFT ACTIVE THERMAL CONTROL• On-orbit radiative heat sink• On-orbit evaporative heat sink• Ascent/entry evaporative heat sinks• Vehicle circulating liquid cooling system• Cabin heat sink• Fuel cell heat sink• Hydraulics heat sink• Cold-plate electronics heat sink• Payload heat sinkSpacecraft Active Thermal Control Subsystem________________________________________Active Thermal Control Subsystem Functions:• Collect waste thermal energy from orbiter subsystems• Reject waste-heat radiatively to space (on-orbit)• Augment space radiators with evaporative heat sink athigh-load/hot-environments• Throttle radiators to restrict heat rejection and utilizeevaporative heat sink to consume excess fuel cell