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#1 2003-06-13 10:25:41

RobertDyck
Moderator
From: Winnipeg, Canada
Registered: 2002-08-20
Posts: 6,168
Website

Re: ISS life support - technical details of existing system

I have a question for anyone who wants to do some digging. What are the technical details of the existing life support system for the International Space Station? I know it is based on electrolysis of water, regenerable CO2 recovery, and dumping the hydrogen and CO2 into space. The effluent from the dehumidifier and urine collection system are purified with filters to produce potable (drinkable) water and some of that water feeds the electrolysis system.

What exactly is the mass, electricity required, and oxygen produced by the current system? It may be a bit more difficult to get these details for the Russian modules, but Hamilton Sundstrand has equipment scheduled to be launched. The SPE ® Oxygen Generation Assembly (OGA) uses a Proton Exchange Membrane (PEM) and is selectable between 4.0 and 20.4 pounds of O2 per day, the maximum oxygen pressure is 45psia, and the maximum hydrogen pressure is 80psia. It is scheduled to be launched to be part of ISS module Node 3, and launched on ISS assembly flight 20A, Space Shuttle flight STS-122. NASA's web site for ISS assembly does not list any flights beyond 15A, and lists Node 1 and 2, but not Node 3.

Hamilton Sundstrand also produces a Water Processor Assembly (WPA). It will produce potable quality water from humidity condensate, reclaimed urine distillate, and waste shower, handwash and oral hygiene waters. Primary treatment is provided by particulate filtration, ion exchange, and carbon sorption. In addition, a high-temperature catalytic oxidation process removes residual organics and kills microorganisms to meet final potable water quality specifications. It is also scheduled for ISS assembly flight 20A/STS-122. Its specifications are:
Flow rate: 500 lbs./hr (Delivery) 
Power: 915 watts
Size: 75 ft^3
Weight: 1,450 lbs. 

Hamilton Sundstrand Regenerable CO2 Removal System is designed to support the spacesuit (EMU). It is located in the airlock and is already on orbit. It replaces non-regenerable lithium hydroxide (LiOH) carbon dioxide (CO2) removal system located in the EMU’s Primary Life Support System. The Metox system consists of two principal components: (1) a regenerator assembly; and (2) a metal oxide sorbent canister. The process involves carbon dioxide removal and the subsequent regeneration of the sorbent material. The metal oxide canister integrates a set of metal oxide sorbent sheets for CO2 removal with an activated charcoal bed for Trace Contaminant Control. After each EVA, the Metox Canister is removed from the EMU LSS “back pack” and placed in the regenerator assembly. The Metox regenerator assembly is designed for use in the ISS Airlock to regenerate up to two Metox Canisters at a time. The metal oxide sorbent is regenerated by flowing air at approximately 400º F at 7.5 scfm through each expended canister for a duration of 10 hours. This is followed by a 4 hour cool down period to return the canisters and oven to a “safe touch” temperature. Specifications:
Canister is designed to maintain the inspired partial pressure CO2 at less than 7.6 mm Hg up to and including a metabolic rate of 1,600 BTU/hour (469 Watts) for a total loading of 1.48 lbs. (0.67kg) of CO2, minimum
Metox system will maintain this CO2 removal performance for at least 55 adsorb/desorb cycles
Power: 1000 watts peak (Metox Regenerator)
Pressure: Canister can withstand pressures of 0 - 16 psia during EMU CO2 removal, 14.5 - 15.2 psia during airlock regeneration
Size: 17.72 in. high x 19.0 in. wide 30 in. deep (Metox Regenerator), 10” x 14” x 3.5” (Metox Canister) 
Weight: 105 lbs. (Metox Regenerator), 32 lbs. (Metox Canister in regenerated state) 

Now here is the big question. What is the weight, size, and power required for the Oxygen Generation Assembly?

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#2 2003-11-28 06:22:03

Palomar
Member
From: USA
Registered: 2002-05-30
Posts: 9,734

Re: ISS life support - technical details of existing system

Mystery Sound Startles Space Station Crew

*I wonder if the words "Apollo 13" raced through their minds.  :-\  I wonder if they got indigestion despite continuing on with their modest Thanksgiving dinner.

I combed through all previous threads relative to the ISS; I didn't want to start a new one, so have inserted the article here (since occurrences like these could have the potential to endanger life support).

Yipes.

--Cindy


We all know those Venusians: Doing their hair in shock waves, smoking electrical coronas, wearing Van Allen belts and resting their tiny elbows on a Geiger counter...

--John Sladek (The New Apocrypha)

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#3 2003-11-28 08:33:43

Shaun Barrett
Member
From: Cairns, Queensland, Australia
Registered: 2001-12-28
Posts: 2,843

Re: ISS life support - technical details of existing system

Hmmm.
    Yeah, I think that would have made me nervous!
                                                 yikes:


The word 'aerobics' came about when the gym instructors got together and said: If we're going to charge $10 an hour, we can't call it Jumping Up and Down.   - Rita Rudner

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#4 2003-11-28 12:17:11

RobertDyck
Moderator
From: Winnipeg, Canada
Registered: 2002-08-20
Posts: 6,168
Website

Re: ISS life support - technical details of existing system

I haven't looked at this thread since I created it.

Hamilton Sundstrand's web site describes the Sabatier Reactor Subsystem they built for the Johnson Space Center's Advanced Life Support Project. It says "We are currently scarring the International Space Station Oxygen Generator System rack to accept the Sabatier Reactor Subsystem. We are also pursuing the use of Sabatier to support future exploration missions." But it doesn't list size, weight, or power requirements. There is an email address to ask for more information about it, but lets just say the prototype is complete and the ISS flight unit is under development.

"Space toilet"
The Waste Collector Subsystem (WCS) is the main item in the Hygiene compartment. The WCS provides for the collection of human waste, both liquid and solid, including vomitus and all hygiene related materials including, but not limited to, fecal wipes and sanitary napkins. The WCS has the ability to support missions of unlimited length through safe and convenient maintenance. Air entrainment is utilized to pull liquid and solid waste away from the user. The WCS removes bacteria, vomitus, trash, fecal odors, hair, skin particles and other body particles from the entrainment air before the air returns to the cabin. Urine is collected by a separate air stream, where it is separated and pumped to a Urine Processor Assembly (UPA).
Power: Urine & Feces Collection: 340 - 375 watts
Power: Feces Compaction/Processing: 250 watts
Size: 27” x 27” x 46”
Weight: 246 lbs.

Dehumidifier
The Common Cabin Air Assembly (CCAA) in the U.S. On-Orbit Segment modules of ISS provides the capability to control the cabin air temperature, maintain the cabin air humidity level within limits, and generate ventilation air flow. The CCAA includes orbital replaceable unit (ORU) subassemblies for the fan, condensing heat exchanger, water/gas separator, liquid & temperature sensor, temperature control valve, and an electronics box. The Common Cabin Air Assembly is used in four U.S. modules: Hab, Lab, Node 2, and Airlock.
Air flow rate is 300 - 500 cfm, coolant water flow rate is 600 - 1,290 lbs./hr
Power: Peak sensible heat removal is 2,032 watts, Peak latent heat removal is 1,000 watts
Moisture removal is 0.76-3.20 lbs./hr
Size: 17.5" x 53.5" x 20.34"
Weight: 212.6 lbs. max

There is a separate "Temperature and Humidity Control" unit listed, but no description. Probably because the CCAA is used instead.

The Marshall Space Flight Center has developed the Urine Processor Assembly. The CO2 sorbent system for ISS cabin air isn't listed on Hamilton Sundstrand's web site either. That still leaves us a few components to get details if we want to examine the ISS life support system as a model for Mars.

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#5 2003-11-30 18:29:59

Palomar
Member
From: USA
Registered: 2002-05-30
Posts: 9,734

Re: ISS life support - technical details of existing system

Mystery Sound Startles Space Station Crew

*I wonder if the words "Apollo 13" raced through their minds.  :-\  I wonder if they got indigestion despite continuing on with their modest Thanksgiving dinner.

I combed through all previous threads relative to the ISS; I didn't want to start a new one, so have inserted the article here (since occurrences like these could have the potential to endanger life support).

Yipes.

--Cindy

*I happened to catch the tail-end of an item on the news last evening.  One of the ISS crewmembers (didn't catch the name) who has been on the ISS at least twice reported similar unexplainable sounds (like in the story in the link).  Other crewmembers have said the same thing.  Some people are putting around the notion that the ISS is "haunted"...(yeah, I know...I'm just relating the rumor)   wink

--Cindy


We all know those Venusians: Doing their hair in shock waves, smoking electrical coronas, wearing Van Allen belts and resting their tiny elbows on a Geiger counter...

--John Sladek (The New Apocrypha)

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