SPACE: Why so much EVA on ISS?

Date: Sat Mar 17 2001 - 06:38:31 MST

Utter space-geek that I am, I spend way too much time reading about and
watching video of the construction of the ISS. Here's a question for the
pros in the space biz: Why is there so much EVA work required? It looks to
me like well over half the tasks being performed by the folks in the big
bulky white suits is making connections of power and data cables. It seems
like all (or at least most) of these connections could be built into a
standard mechanical system that would mate up automatically as part of the
module berthing process. I understand why you would want the basic docking
devices to be relatively "clean" mechanical systems, and also why the
structural connections need to be mechanically simple. But why not have a
standard mechanical bus along the outside of each module that is motor-driven
to mate up with its counterpart on the adjoining node after the soft and hard
docking has been completed? This bus could carry all the power and data
cabling you need, with built-in spares. Actual circuit logic could be
controlled via switches and termination cabinets inside the pressurized

It seems like designing a standard modular protocol for power and data bus
connections would be an important part of developing a robust space
infrastructure. I've envisioned a basic system in which design modules are
applied to one or two basic structural "envelopes", a la LEGOs(tm). You see
hints of this in the video downlinked in the last couple of days from ISS in
the way that the Italian Leonardo MPLM "moving van" is just a simplified
version of the design for the US lab module in size, shape and basic
mechanical structure. Why isn't this approach applied at a finer-grained
level to the power and data cabling?

       Greg Burch <>----<>
      Attorney ::: Vice President, Extropy Institute ::: Wilderness Guide -or-
                                           ICQ # 61112550
        "We never stop investigating. We are never satisfied that we know
        enough to get by. Every question we answer leads on to another
       question. This has become the greatest survival trick of our species."
                                          -- Desmond Morris

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