GREETINGS FROM A NEW MENBER & IDEAS FOR THE ATMOSPHERE IN ISLAND ON

FOR THE ATMOSPHERE IN ISLAND ONE
Date: Thu, 26 Jul 2001 08:09:15 -0500
Because at lower atmospheric pressure, the structural requirements
for habitats are vastly reduced. Some millions in research here on
Earth might save us billions on construction costs in space.

Maybe, but maybe not.
Structural materials will become relatively inexpensive.
The first million tons will be the most difficult :-)
The difference in cost between a 0.3 bar pressure vessel versus a 1.0
bar pressure vessel
in terms of the cost of materials is what ?

Somebody check me on this:

The stress increases by a factor of 3.3,
so the wall cross section area must increase by a factor of 3.3,
so the thickness of the wall increases by a factor of 3.3,
so the volume of materials increases by a factor of 3.3

The cost will increase LESS than by 3.3 because the first million tons
is the most difficult.
What this means is that there will be a curve where the cost per ton
decreases with the quantity of material produced.

So let us guesstimate that the cost increases by a factor of two. It
might be a lot less.

How this compares to the cost of low pressure research is a bit more
difficult to calculate.

It depends a lot on the diversity of the materials set set and bio-set
which must be tested.
This uncertainty represents quite a big planning risk, which will make
it more difficult to get investment.
Also, this research might identify a set of life-forms or materials
which cannot safely be maintained in low pressure for any significant
length of time. That might limit planning options considerably.

Hence, it may well be a lot easier to sell a 2x cost increase (or
less), versus an unknown research cost which could exceed 2x by "a lot".