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Old September 20th 08, 07:29 AM posted to sci.space.shuttle,sci.space.history,sci.space.policy,sci.space.station
Pat Flannery
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Posts: 18,465
Default Shuttle program extension?



Jeff Findley wrote:

So what? A pound of water is a hell of a lot cheaper than a pound of
extruded aluminum, a pound of machined titanium, or a pound of TPS material.
You're falling into the aerospace engineering trap that lighter is always
cheaper.

Why don't you check up on the total amount of water used by weight per
crew member per day on the ISS?
For a crew of four it's 40,000 pounds per year:
http://library.thinkquest.org/J01121...ce_station.htm
starting with that, extrapolating it to a full six-person crew, and it's
60,000 pounds of water per year.
Divide that by four for the intended three month lifespan of your
lifeboat, and you have to drag along 15,000 pounds of water alone to
give the crew something to drink, cook, and wash with while they are
orbiting up there awaiting rescue.
Then stick all the food aboard, the oxygen supplies, the CO2 scrubbers,
and the solar arrays, and your lifeboat is around the weight of two or
three Salyut space stations.
This "lifeboat" is medium-sized space station unto itself as far as mass
goes.
It's like your plan for the orbiting refueling stations; you get so
enraptured by a concept that the actual costs of doing it are ignored,
and what you end up with is doing something fairly simple in a much more
complex and expensive way...due to some sort of preconceived
philosophical conceit in regards to how it _should_ be done in your own
mind, rather than the cheapest way of doing it in reality.

Pat