MARYLAND. Overview Major Component Systems Open-loop Life Support Physico-Chemical Bioregenerative Extravehicular Activity U N I V E R S I T Y O F

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1 Overview Major Component Systems Open-loop Life Support Physico-Chemical Bioregenerative Extravehicular Activity 2005 David L. Akin - All rights reserved umd.edu

2 Life Support Block Diagram O2 CO2 Water Nutrients Waste Stores Humans

3 Life Support Block Diagram Food Preparation O2 CO2 Water Nutrients Waste Stores Atmosphere Management Humans Hygiene Facilities Water Management Waste Management

4 Life Support Block Diagram Plants & Animals Food Preparation O2 CO2 Water Nutrients Waste Stores Atmosphere Management Humans Hygiene Facilities Water Management Waste Management

5 Essentials of Life Support Air Constituent control CO 2 scrubbing Humidity control Particulate scrubbing O 2, N 2 makeup Temperature control Water Food Waste Management

6 ISS Life Support Schematic From Peter Eckart, Spaceflight Life Support and Biospherics, Kluwer Academic, 1996

7 ECLSS Mass Balance

8 ISS Consumables Budget Consumable Design Load (kg/person-day) Oxygen 0.85 Water (drinking) 1.6 Water (in food) 1.15 Water (clothes and dishes) 17.9 Water (sanitary) 7.3 Water (food prep) 0.75 Food solids 0.62

9 Effect of Regenerative Life Support Open loop life support 100% resupply + Waste water recycling 45% + CO 2 absorbent recycling 30% + O 2 regenerate from CO 2 20% + Food from wastes 10% + Eliminate leakage 5%

10 Air Revitalization Processes From Peter Eckart, Spaceflight Life Support and Biospherics, Kluwer Academic, 1996

11 Cabin Atmospheric Pressure Past choices driven by minimum mass Mercury/Gemini: 100% O 3.5 psi Apollo: 100% O 5 psi Skylab: 80% O 2 /20% N 5 psi Shuttle/ISS: 21% O 2 /79% N 14.7 psi Issues of compatibility for docking vehicles, denitrogenation for EVA Current practice driven by avionics, concern for research protocols

12 Oxygen Makeup Systems Gaseous O 2 storage (also N 2 ) Typical pressures 200 atm (mass optimized) to atm (volume optimized) 2 kg tank/kg O 2 Liquid O 2 storage (also N 2 ) Requires 210 kj/kg for vaporization (~2W/person) Supercritical storage T= C, P=49.7 atm kg tank/kg O 2 Solid perchlorates ( candles ) LiClO 4 --> LiCl + 2O C 2.75 kg LiClO 4 /kg O 2 (Typically 12.5 kg with packaging)

13 Superoxides and Ozonides O2 generation KO 2 + 2H 2 O --> 4KOH + 3O 2 KO 3 + 2H 2 O --> 4KOH + 5O 2 CO2 reduction 4KOH + 2CO 2 --> 2K 2 CO 3 + 2H 2 O 2K 2 CO 3 + 2H 2 O + 2CO 2 --> 4KHCO 3 KO2 removes 0.31 kg CO2/kg and generates 0.38 kg O2/kg

14 Nonregenerable O2 Production Material kg(material)/kg(o2) H2O2 2.1 LiO K2O MgO CaO LiClO4 2.8 KClO Mg(ClO4) Allocate an additional 10 kg/kg O2 for packaging, in addition to combustion receptacle (mass TBD)

15 Electrolytic Oxygen Generation Static Feed Water Electrolysis Solid Polymer Water Electrolysis Water Vapor Electrolysis CO2 Electrolysis

16 CO 2 Scrubbing Systems CO 2 production ~1 kg/person-day Lithium hydroxide (LiOH) absorption Change out canisters as they reach saturation 2.1 kg/kg CO 2 absorbed Also works with Ca(OH) 2, Li 2 O, KO 2, KO 3 Molecular sieves (e.g., zeolites) Porous on the molecular level Voids sized to pass O 2, N 2 ; trap CO 2, H 2 O Heat to C to regenerate 30 kg/kg-day of CO 2 removal; 200W

17 Nonregenerable CO2 Absorbers Material kg(material)/kg(co2) LiOH 1.09 Ca(OH) Allocate an additional 1.0 kg/kg(co2) for packaging Only works down to PPCO2 levels of ~0.5 kpa

18 CO 2 Regenerable Scrubbing Systems CO 2 production ~1 kg/person-day 4-Bed Molecular Sieves (4BMS) Dual paths (one scrubbing, one regenerating) Desiccant bed for moisture removal, 5 A zeolite sieve for CO2 Heat to C to regenerate 30 kg; 0.11 m 3 ; 170 W (all per kg-day of CO 2 removal) 2-Bed Molecular Sieves (2BMS) Carbon molecular sieve for CO 2 16 kg; 0.09 m 3 ; 77 W (per kg/day CO 2 )

19 CO 2 Regenerable Scrubbing Systems Solid Amine Water Desorption (SAWD) Amine resin absorbs H 2 O and CO 2 ; steam heat regenerates Amine + H 2 O --> Amine-H 2 O (hydrated amine) Amine-H 2 O + CO 2 --> Amine-H 2 CO 3 (bicarbonate) Amine-H 2 CO 3 + steam --> Amine + H 2 O + CO 2 17 kg; 0.07 m 3 ; 150 W (all per kg-day of CO 2 removal)

20 CO 2 Regenerable Scrubbing Systems Electrochemical Depolarization Concentration (EDC) Uses fuel-cell type reaction to concentrate CO2 at the anode CO2 + 1/2O2 + H2 --> CO2 + H2O + electricity + heat CO2 and H2 are collected at anode and directed to CO2 recycling system (combustible mixture!) 11 kg; 0.02 m 3 ; 60 W (all per kg-day of CO 2 removal); does not include reactants for power output

21 CO2 Membrane Removal Systems Osmotic membranes Poor gas selectivity Returns CO2 to cabin air Electroactive carriers Electroactive molecules act as CO2 pump Very early in development Metal Oxides AgO2 absorbs CO2 (0.12 kg O2/kg AgO2) Regenerate at 140 C for 8 hrs (1 kw) cycles Replacing LiOH in EMUs for ISS

22 CO 2 Reduction Sabatier reaction CO 2 + 4H 2 --> CH 4 + 2H 2 O Lowest temperature ( C) with Ni catalyst Electrolyze H 2 O to get H 2, find use for CH 4 91 kg; 3 m 3 ; 260 W (all per kg-day of CO 2 removal) Bosch reaction CO 2 + 2H 2 --> C + 2H 2 O 1030 C with Fe catalyst C residue hard to deal with (contaminates catalyst) 700 kg; 3.9 m 3 ; 1650 W (all per kg-day of CO 2 removal)

23 CO 2 Reduction Advance Carbon-formation Reactor System (ACRS) CH 4 --> C + 2H 2 Lowest temperature ( C) with Ni catalyst Electrolyze H 2 O to get H 2, find use for CH 4 60 kg; 0.1 m 3 ; 130 W (all per kg-day of CO 2 removal)

24 Nitrogen Makeup Nitrogen lost to airlock purges, leakage (can be >1%/day) Need to replenish N 2 to maintain total atmospheric pressure Choices: High pressure (4500 psi) N 2 gas bottles Cryogenic liquid nitrogen Storable nitrogen-bearing compounds (NH 3, N 2 O, N 2 H 4 )

25 Trace Contaminant Control Particulate Filters (dusts and aerosols) Activated Charcoal (high molecular weight contaminants) Chemisorbant Beds (nitrogen and sulpher compounds, halogens and metal hybrids) Catalytic Burners (oxidize contaminants that can t be absorbed) 100 kg; 0.3 m 3 ; 150 W (all per person-day)

26 Water Management Distillation Processes Vapor Compression Distillation (VCD) Thermoelectric Integrated Membrane Evaporation (TIMES) Vapor Phase Catalytic Ammonia Removal (VAPCAR) Air Evaporation Filtration Processes Reverse Osmosis (RO) Multifiltration (MF) Electrodialysis

27 Water Distillation Vapor Compression Distillation (VCD) 300 kg; 1.5 m 3 ; 350 W (for 100 kg H2O processed per day) VAPCAR 550 kg; 2.0 m 3 ; 800 W (for 100 kg H2O processed per day) TIMES 350 kg; 1.2 m 3 ; 850 W (for 100 kg H2O processed per day)

28 Water Revitalization Processes From Peter Eckart, Spaceflight Life Support and Biospherics, Kluwer Academic, 1996

29 Waste Management Processes From Peter Eckart, Spaceflight Life Support and Biospherics, Kluwer Academic, 1996

30 Bioregenerative Life Support Schematic From Peter Eckart, Spaceflight Life Support and Biospherics, Kluwer Academic, 1996

31 Life Support Systems Analysis (example) From Peter Eckart, Spaceflight Life Support and Biospherics, Kluwer Academic, 1996

32 Mercury ECLSS Schematic

33 Gemini ECLSS Schematic

34 Apollo LM ECLSS Schematic

35 References Peter Eckart, Spaceflight Life Support and Biospherics, Kluwer Academic, 1996 Wiley Larson and Linda Pranke, Human Spaceflight: Mission Analysis and Design, McGraw- Hill A. E. Nicogossian, et. al., eds., Space Biology and Medicine - Volume II: Life Support and Habitability, American Institute of Aeronautics and Astronautics, 1994 Susanne Churchill, ed., Fundamentals of Space Life Sciences, Krieger Publishing, 1997