From: kentm@aix.rpi.edu (Michael V. Kent)
Subject: Re: One Small Step for a Space Activist... Vol 3 No 9
Organization: Rensselaer Polytechnic Institute, Troy, NY
Date: Thu, 10 Sep 1992 03:27:53 GMT

In article <1992Sep9.193128.20635@iti.org> aws@iti.org (Allen W. Sherzer) writes:
>On the plus side, station supply will mean placing a lot of
>mass into LEO, and this could make the market for launch
>services a LOT bigger, which could help reduce launch
>costs. But the way things currently are, NASA intends to use
>only the Shuttle (with its high cost) for resupply. Not only

NASA intends to use only the Shuttle for resupply ONLY until something 
better comes along.  Also, one of the design missions of the Delta Clipper
is station resupply.

>If a way to resupply Freedom could be found which didn't
>require Shuttle, the payback would be enormous. Not only
>would the larger launch markets lower costs, but non-Shuttle
>based resupply could mean that the entire Shuttle program
>can be phased out, freeing up roughly three BILLION every year.

The mistake here is thinking of the Shuttle as a launch vehicle.  It is not.
A second mistake is thinking its sole mission is Station resupply.  That, too,
is untrue.  If Station resupply is offloaded to another vehicle, you still 
want to keep the Shuttle around for missions like EURECA, TSS, SHARE, CIRRUS,
Hubble revisits, satellite repair, retrieving, and servicing, etc.  These
are missions which still need to be done and that the Shuttle was designed to
do.

Remember, the Shuttle is not a launch vehicle.  It is a space transportation
system (hence the acronym STS).  It includes things like the OMS and RCS for
multiple satellite rendezvous, the robot arm, astronauts-on-demand for
contingency spacewalks, the MMU, Spacelab, the Spacelab mounting hardware
(for things like Astro), the Shuttle Palette Satellite, and some things
harder to quantify like the attitude control capability (essential for 
missions like Astro and STS-39).

Your station resupply vehicle will offer few of those things.  It is a
valuable first step but a small one.  It will not replace the Shuttle.

>So what do we need to do? We need to: 1)Fly about 160,000
>pounds of supplies and experiments up and about 50,000
>pounds back down (returned cargo will need low-G return);
>2)Fly four crew to and from Freedom four times a year; and
>3)An Orbital Transfer Vehicle needed to transport payloads
>to Freedom (this is needed since we are eliminating
>Shuttle).

Please note two things.  NASA would like to go to a 180-day rotation about
two years after PMC (instead of 90 days).  Also, NASA plans to expand the
station to an eight man crew (EMCC).  Plan your vehicle accordingly.

>Such an HLV should be a commercial procurement where the
>government buys launch services only (as required by current
>federal law). Two candidates are Heavy Lift Delta (see One
>Small Step... Vol. 2 No 2) and Titan V (see One Small 
>Step... Vol. 2 No 3). Both manufacturers have already offered
>to sell launch services for either vehicle for less than $200
>million per launch (including development costs).

I like the heavy-lift idea, but I don't think they fill the mission well.
It seems like you're adapting a mission to the vehicle and not the other
way around.  (You could argue NASA is doing the same with the Shuttle, but
the Shuttle already exists.  These vehicles do not).  If you're going to
build a new vehicle, build it to the mission requirements.  (If I were
a station manager, I'd rather have 5 flights of 20,000 lbs each than one
flight of 100,000 lbs.  It offers much more flexibility).

>Meeting requirement 2 is easy: we can use a Russian Soyuz-TM
>launched on an Atlas or Titan vehicle. All the components
>exist today and have been used extensively. The only thing

You want to use an Atlas?  The rocket that goes "boom" a lot?  (Rockets
should go roooar, not boom  :)  ).  We used to launched manned missions
on the Atlas, but we didn't have much of a choice then.

>Finally, we need an Orbital Transfer Vehicle (OTV) to move
>payloads to Freedom. This capability is not strictly needed
>and will be rarely used but will allow us to phase out
>Shuttle. This vehicle has already been costed at $3 billion
>to develop.

I think you want the Orbital Maneuvering Vehicle (OMV).  The OTV was meant
to move payloads between LEO and GEO.  (An OTV is nice, but we need an OMV
first).

Mike

-- 
Michael Kent                                   kentm@rpi.edu
McDonnell Douglas                              Rensselaer Polytechnic Institute
All facts in this post are based on publicly available information.  All
opinions expressed are solely those of the author.    Apple II Forever !!
Newsgroups: talk.politics.space