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Worth research. Right now I would advocate a Mars suit as MCP. No contractile polymer or shape memory alloy, just tight Spandex. Air bladder vest made of neoprene rubber. Outer shell, two pieces of shaped polymer to squish the bladder close to the body. Just buckles to hold the front half to the back. Outer garment a parka with Thinsulate insulation, outer fabric could be Tenara or Orthofabric. Head-worn crash helmet, with closed cell foam, then fluoropolymer sheet as backup pressure layer, then open cell foam comfort layer. Double pane polycarbonate visor.
PLSS backpack of silver oxide granules. More durable than amine. Oxygen bottle COPV. Drinking water a 1 litre bottle with polymer film bladder liner. No cooling system because an MCP suit cools with sweat. If you want to be fancy, you could add a smaller COPV with backup oxygen. Micro controller with sensors connect to a smartphone. Pocket for a smart phone in sleeve on back of wrist. Cable for both data and power from backpack to smartphone. Extended duration battery in backpack. Design to keep water bottle, battery, and smartphone warm by astronaut body heat.
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RobertDyck,
You could be right, but the amine swing bed has operated aboard ISS for multiple years now. Zeolites were first used aboard Skylab, so NASA has considerable experience with them. The original CDRA aboard ISS also used zeolites. It's little wonder that CAMRAS and RCA use zeolites as well. We're also talking about modified / functionalized zeolites to stabilize the amines by bonding them to the zeolite. There's an ever-growing body of research behind them, because they're also being used for direct air capture of CO2. All I know for sure is that a lot of different groups are pouring intellectual and monetary efforts into researching zeolites and other metal-oxide frameworks for CO2 removal. I think it's also worth noting that NASA's amine swing bed uses hard vacuum to extract the CO2, rather than high temperatures alone. The amines used in their CO2 removal systems last for 3 to 5 years.
Carbon Dioxide Removal Technologies for U.S. Space Vehicles: Past, Present, and Future
Even China is getting in on the action:
Amine-immobilized HY zeolite for CO2 capture from hot flue gas
Amines were immobilized by HY zeolite by ionic bond showing exceptional thermal stability.
AmineHY zeolite presented cyclic CO2 adsorption capacity higher than other grafted amines.
AmineHY zeolite presented better CO2 over N2 selectivity than parent material.
AmineHY are promising for carbon capture from hot postcombustion flue gases.
Abstract
Solid amine-based adsorbents were widely studied as an alternative to liquid amine for post-combustion CO2 capture (PCC). However, most of the amine adsorbents suffer from low thermal stability and poor cyclic regenerability at the temperature of hot flue gases. Here we present an amine loaded proton type Y zeolite (HY) where the amines namely monoethanolamine (MEA) and ethylenediamine (ED) are chemical immobilized via ionic bond to the zeolite framework to overcome the amine degradation problem. The MEA and ED of 5%, 10% and 20% (mass) concentration – immobilized zeolites were characterized by X-ray diffraction, Fourier-transform infrared spectroscopy, and N2 −196 °C adsorption to confirm the structure integrity, amine functionalization, and surface area, respectively. The determination of the amine loading was given by C, H, N elemental analysis showing that ED has successfully grafted almost twice as many amino groups as MEA within the same solvent concentration. CO2 adsorption capacity and thermal stability of these samples were measured using thermogravimetric analyser. The adsorption performance was tested at the adsorption temperature of 30, 60 and 90 °C, respectively using pure CO2 while the desorption was carried out with pure N2 purge at the same temperature and then followed by elevated temperature at 150 °C. It was found that all the amine@HY have a substantial high selectivity of CO2 over N2. The sample 20% ED@HY has the highest CO2 adsorption capacity of 1.76 mmol∙g−1 at 90 °C higher than the capacity on parent NaY zeolite (1.45 mmol∙g−1 only). The amine@HY samples presented superior performance in cyclic thermal stability in the condition of the adsorption temperature of 90 °C and the desorption temperature of 150 °C. These findings will foster the design of better adsorbents for CO2 capture from flue gas in post-combustion power plants.
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If you recover the CO2 for either a Sabatier or MOXIE then recovery with vacuum requires a vacuum pump. Another piece of equipment for the PLSS, and more power.
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RobertDyck,
It's a question of priorities. If we're developing a long-term / next generation personal spacecraft solution, that's MCP suits with advanced PLSS powered by nuclear batteries to provide long duration life support, even if there's no specific intent to wear the suits for more than 8 hours at a time. On top of that, we have layered fire / heat / cold protection and CNT or BNNT / PEEK plate armor to protect a person's vitals against high velocity debris strikes in space or on the moon as well, but not Mars. It's secondary function is radiation attenuation, to the degree that it can. The goal here is to provide more protection in a more practical manner, even when it's not strictly necessary for all possible use cases. You don't need thermal protection or ballistic plates at high noon on Mars at the equator, but when the Sun sets, you'll need that thermal protection or you'll freeze to death. All parts of the suit don't need to be worn all the time. That's the true beauty of the modular MCP design- it can be tailored to protect against most environmental threats.
I absolutely believe that a MCP suit combined with whatever the best current life support tech we have should go into the system design so that we have something more capable right now. As of right now, the ready-to-go PLSS uses a rapid cycle amine swing bed. Maybe a next generation PLSS should use Silver. What I tried to convey to you is that all current knowledge involves the use of functionalized zeolites. Nowhere did I ever claim amine swing bed tech was "the best", it's merely what we have available, with a very large body of research and operational experience to draw upon. If Silver is better, then amine should be phased out as operational experience accumulates.
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Silver has the advantage of being more compact, lower volume. Amine with its substrate is lower mass but larger volume. For a backpack, the mass is offset by requiring a larger pressure vessel to contain it. What they're using on ISS right now is silver oxide for the PLSS of EMU spacesuits, but what you said for the station. Most likely the amine swing bed will be better for a Mars habitat as well. Different applications, different requirements result in different solutions.
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