[FPSPACE] JimO's analysis of the ISS

Keith Gottschalk kgottschalk at uwc.ac.za
Mon Jul 5 07:25:20 EDT 2010


       About a fortnight ago, JimO posted here an analysis of lessons learned from the first decade of the International Space Station.

      One of them was that any international space partnership that includes Russia has to make the trade-off of adding another 15 degrees or so onto the orbital inclination of the space station, with the main downside of significantly lowering payloads to orbit. Until the decade when, at last, the first HOTOL RLVs replace our ELVs, there is no dodging this consequence of the old Soviet Union building its major cosmodrome in Kazakhstan instead of say either Turkmenistan or Azerbaijan.

   Perhaps in future we will have at least two space stations, one inclined to accommoate Russian partners, & a heavier one flying over only Canaveral, Kourou, Alcantara, Sriharikota, Kagoshima, & Hainan.

     But the most interesting of JimO's reflections is one that is counter-intuitive, at least to laypersons.

    JimO argues that the ISS has gained robustness, and depth of safety & redundancy, precisely because it is NOT a completely integrated system, with modules made by international partners as mere contractors. From the engineering & functional perspective, JimO implies that the ISS is more co-orbiting, semi-autonomous modules, that are bolted together. So by the law of averages, whenever one life-critical sub-system conks out (O2, extracting CO2,  IT, power, toilet) the other modules keep everybody's heads above water.

      No one has sought to refute this most interesting point, and it has profound implications when, like now, we have once again revived discussions of human spaceflight beyond the Moon. The old Werner von Braun Marsprojekt proposals of 1942-56 was for a fleet of about seven spacecraft to fly to Mars. Now, not even WvB's charm & charisma could ever get Congress, or Ferdinand & Isabella, to pass the budget for such a Magellan-style squadron! But in the event of a catastrophe, a crew en route to Eros or Phobos cannot huddle in a Soyuz or Orion lifeboat for eight months.

    This indicates that an absolute minimum of two spacecraft flying in formation, each with lifeboats, is critical to give the depth of safety that human spaceflights of months will demand. (Not to mention the British Interplanetary Society's proposed Daedelus for interstellar spaceflight :)  Columbus & Magellan both had a 3-ship squad.

        It also raises major debate about how the architecture & engineering can best design redundancy in spacecrafts intended for months-long flights to Vesta or Mars. What do engineers on FPSPACE think? Should such spacecraft have autonomous modules that go far beyond the provisions of watertight bulkheads & O2 candles of the compartments aboad our atomic-powered submarines?

Keith

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