Space, Technology and Society

Regenerative Life Support

10 Comments

Listening to an interesting presentation on challenges of closing the cycle on ISS, particularly water. Not seeing any real surprises, but I think that this will be a very useful result of having the station for improving systems. They’re learning about life of various system elements, and getting some surprises, with some failure years before expected, and some lasting much longer.

10 thoughts on “Regenerative Life Support”

  1. Yes, I had mentioned that I had long ago seen a mockup of an Apollo CM at the Chicago Museum of Science and Industry, and I had seen how Lloyd Bridges on “Sea Hunt” was always limited by the amount of air in rather bulky oxygen tanks, and I got to wondering if they were going to grow algae for their oxygen in that small spacecraft.

    OK, OK, watching “Sea Hunt” was how a kid of age 8 estimated the amount of breathing gas you needed for a lunar mission. It may seem simplistic to you, but it was the best source of information I had at that age in the pre-Internet era.

    I guess Apollo, ISS, and ballistic missile subs all use/used a chemical rather than a biological regenerative system for the air supply.

    But whatever became of biological regenerative systems, a “closed ecosystem” for food, water and air? I guess the Biosphere 2 folks tried that unsuccessfully, but I think they had a misconception of how Biosphere 1 works. Apparently the notion that plants supply us with breathing oxygen on short time scales is wrong — the endowment of atmospheric O2 is a “fossil gas” of processes over geologic time.

  3. Biochemical is chemical. The issue is control and feedback. The smaller the volume, the trickier it is too manage, but obviously something we can learn to manage.

    Then there’s the issue of graceful failure. A system has to allow for failure and recovery without killing anybody.

    The good news is the tolerances are known and not unmanageably tight. Also, we do not need a perfectly closed system. It just has to be good enough. Knowing it isn’t going to be a perfectly closed system allows us to plan on having resources to recover when slightly off target.

    Asking for perfection is asking for failure.

  4. Rand,

    The other thing I wonder about is how regenerative ECLSS in a hypogravity field (like Martian or Lunar gravity) is going to compare with µ-gravity ECLSS. I know that at least some of the processes get a lot harder when you can’t count on gravity to help, and can’t count on natural convection currents to keep the air better mixed, etc. I don’t know the answer, but I wonder if when we get to the Moon or Mars we discover that some of the ECLSS stuff actually is easier to make work reliably when you have a little gravity helping (and the opposite as well–are there some systems that work better in µ-gravity?).

    All the more reason to do some level of xGRF or G-lab to start learning.

    ~Jon

  5. There were a lot of comments at Space Access this year about the huge value of water in LEO – the fact that they dump water overboard on ISS as a waste product would seem to indicate a lack of actual market for it…

    2. Could there be a market for very small recoverable entry vehicles from ISS? How about one that uses this excess water for transpiration cooling?

  6. Just to correct a mis-statement… Biosphere II ran into trouble because the concrete was still ‘curing’ and chemically bonding O2 out of the air. This sink had not been accounted for, and I am not the least bit surprised that they missed it. That was a big lesson from the experiment. Now the old school types would say that they should have simulated it for a couple decades and poured money into PhD thesis research rather then – my God – BUILDING something and just seeing what happens. I see Biosphere II as a success in what it set out to do. Learn by doing. The only failure was that they should have iterated and kept iterating.

    1. A correction, the concreting in biosphere2 was binding CO2. Excess biomass in the soil was reacting with O2 in the air, then the CO2 was binding to concrete leaving scientists puzzled for awhile where the O2 was going.

      I suspect that if they opened it up and let the system breath for awhile it would eventually come into equilibrium.

    2. Biosphere II was a complete joke. Only idiots would farm dirt with hoes in a closed system, and expect to survive and thrive.

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