Re: forming composit space station skin in situ

Cray74_at_gmail.com
Date: 02/04/05 

To: sci-space-tech@moderators.isc.org
Date: 4 Feb 2005 05:26:53 -0800

Kent Paul Dolan wrote:
> An alternative that has lots of obvious arguments
> going for it, like redundancy for safety reasons,
> more reasonable single-launch lift requirements,
> and a stageable startup, would be to replace the
> "one big sphere" concept with a "bunch of grapes"
> design.

That's a reasonable point.

By halving the diameter of the sphere to 50m, you
quarter the mass of shell that needs to be launched
at once. The mass of air drops 1/8th that of
a 100m sphere, too.

In fact, with a 50m sphere, you would be able to
launch a shell of the same weight as the 100m sphere
but able to handle 4x the internal pressure. That's
a 40-ton payload that gives you the immediate
capability to handle 1 atmosphere of pressure.

Further, if you're playing around with Saturn V-grade
launchers, the required air mass for 1 atmosphere of
pressure (80ish tons) can be delivered in one payload
rather. A single off-the-shelf Delta IV Heavy can
deliver a breathable, 3-4psi oxygen atmosphere for
a 50m sphere.

> but the project could be practical and feasible
> with current technology, instead of straining at
> every seam.

Yep. And at 30-33m spheres (100ft across), you can
much more easily use existing launchers. The shell of
a 33m, 1atm sphere would be about 20 tons.

harmonever...@hotmail.com wrote:

> Does anybody know what the specs for such
> a pressure suit, that would
> deal comfortably with, oh, 1/100 of an atmosphere
> would be?

Yes. It would be something like a normal spacesuit,
minus the thermal and debris protection. The bulk
of the suit would still be present because the
bulk (if not the weight) of a spacesuit is the
pressure-resistant shell and the constant-volume
joints that allow the astronaut to move despite
being stuck in a rigidly-inflated, human-shaped
balloon. A simple flight suit would not be adequate.

The 1/100th atmosphere environment you're
proposing is not much different than a vacuum,
though I think it'll complicate cooling by
making normal sublimative cooling difficult.

> I realized that once the main shells were
> in place, a much smaller internal tent
> could be inflated inside the
> inner shell to house - oh, let's say a
> hemisphere dome 20 meters in diameter.

That's a fairly reasonable approach. However,
you still have some logistical concerns to
deal with, because the initial shell will still
be fairly heavy (c40 tons). That runs into
launch problems.

If you're willing to use a tent approach but
not bend on developing/modifying rockets for
heavier payload capacity, perhaps you should
extend the tent approach to its logical end:

Assemble sections of the main sphere in a
smaller "workshack."

As I noted above, a 30m sphere with a normal
environment would be within the capability of
existing rockets to launch (in perhaps 2 launches).

Over the next 30-35 launches, you could assemble
enough material in the "workshack" to build the
complete, 1atm 100m sphere (with debris shields
and insulation). Workers in the workshack could
(somehow) stitch, glue, and bond this supersized,
multi-walled balloon together and then kick it
out an airlock.

Another 11 launches later, you'd have a minimum
breathable atmosphere in the main sphere, then
about 30 launches later, you'd have a full
atmosphere in the main sphere.

Mike Miller, Materials Engineer

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