Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!swrinde!ucsd!ucbvax!ITI.ORG!aws
From: aws@ITI.ORG ("Allen W. Sherzer")
Newsgroups: sci.space
Subject: Re: LNLL Inflatable Stations
Message-ID: <9011142140.AA02302@iti.org>
Date: 14 Nov 90 21:40:30 GMT
References: <2732@polari.UUCP>
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: Evil Geniuses for a Better Tomorrow
Lines: 89

In article <2732@polari.UUCP>:
>>Since LLNL is a large lightweight structure it will be subject to high drag, 
>+Already included in their budgets. They will use (from memory) 3T a year
>+of fuel for this. An alternativ+e they are looking at is a 10KW ion engine

>The 3T/yr sounds comparable to Freedom, which is much heavier. Weight is a 
>precious commodity, and budgeting extra propellant to allow for 
>high drag is inefficient.  Better to reduce the drag.

If the LLNL Great Exploration plan is enacted, this will not be a problem.
The Earth Station will be next to several hundred tons of fuel. A few years
after launch, the lunar base will begin returning fuel from the moon. These
guys will have fuel coming out of their ears.

However, if they are using the same amount of fuel as Freedom then there
shouldn't be a problem.

>Also increases risk.  The LLNL will decay faster than Freedom if its untried 
>ferry craft becomes grounded.

First of all, since you don't know the Earth Station orbit, I don't see how
you can make that claim. Second of all, who cares if the ferry becomes 
grounded? Since the Earth Station provides artificial gravity the crew
can stay up for arbitrary amounts of time. We send up fuel/consumables on
ELV's (at less cost than the Shuttle) and wait it out.

>Ion engines are a high cost item apparently not included in their baseline 
>price.  

Correct. It is just an example of their constant attention to potential
cost reductions.

>> (already a problem on Freedom), and higher engine duty cycles. Is there any 
>> way they can make it smaller ?
>+An inflatable station could be made smaller for 0G however if they are
>+to maintain artificial grav+ity, it is about as small as they can get. It's

>Sounds like an inherent disadvantage for stations with artifical gravity.

To me it is an advantage. They provide a great lab for researching any
level of gravity from 0 to 1G. Crews can stay up longer periods and cut
billions of $$ from lifetime logistics costs.

>That is not the point.   Any material can carry any load, if it has big
>enough cross section.   It is a question of how heavy it has to be to get low 
>enough stress.     Structure carrying centrifugal loads is heavier than 
>structure which does not.

As I said, it is all calculated in (see the ILC report).

>  Why exactly do LLNL want to spin the thing anyway ?  

I have already said: more research can be conducted and crews/equipment
can be qualified for the moon and Mars. It also allows crews to stay
up longer which saves billions in lifecycle cost.

>I cannot see any advantage where crews are rotated every 90 days.  

Why am I not suprised that a Freedom engineer doesn't think saving money
is a good reason to do something? :-)

>And half the fun for the astronauts is the zero-gee....

They aren't there to have fun. However, there is a zero gee module in
the Earth Station. They can have fun there.

>>In practice the station will need a spun section attached to a despun
>>section.   
>+As I said, already in there. The airlock is at 0G.

>I would still want to despin the station for EVA which could be fairly often.

And they don't. 

>Cannot risk losing an astronaut.  

Then don't send them up.

>Or else LLNL will have to give all their EVA
>crew Manouevering Units;

Why?

    Allen
-- 
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|Allen W. Sherzer| I had a guaranteed military sale with ED-209. Renovation |
|   aws@iti.org  | programs, spare parts for 25 years. Who cares if it      |
|                | works or not?  - Dick Jones, VP OCP Security Concepts    |