From: kentm@aix.rpi.edu (Michael V. Kent)
Subject: Shuttle alternatives (was Re: Terminal Velocity of DCX?)
Organization: Rensselaer Polytechnic Institute, Troy, NY
Date: Wed, 16 Dec 1992 22:25:00 GMT

In article <1992Dec16.195416.8422@iti.org> aws@iti.org (Allen W. Sherzer) writes:

>That is my point.

Your point is a moving target, but I'll do my best to adress its major
aspects.

Point 1:  In the beginning of this mini-thread, Allen stated that for the
cost of one Shuttle flight, NASA could develop DC-X and launch whatever was
to go up on the Shuttle on a Titan IV.

This is not true primarily because Titan IV cannot carry most Shuttle pay-
loads.

1) Titan IV cannot carry the payload of the Shuttle.  Titan IV's payload is
only 38,500 lbs to a 100 nmi orbit, while Discovery and Atlantis can loft
52,000 lbs to a 150 nmi orbit.  Endeavour can launch a few thousand lbs more.
While I don't have the equations on hand, raising Titan IV's standard orbit
to 150 nmi would cause its payload to drop to about 30,000 lbs, barely half
that of Endeavour.

2) Shuttle is the only manned spacecraft we have.  An astronaut will not sur-
vive long in a Titan IV payload fairing, as the fairing has no life support
system.  This is important for the middeck payloads, Spacelab, and Spacehab.
It is also important for satellite servicing missions where astronaut pres-
ence is required for primary (Intelsat, Hubble servicing) or contingency
(Hubble, Compton deploy) purposes.

3) Titan IV has no return capability.  This is important for all astronaut
operations, and is required for satellite retrieval missions.  It is also 
required for SPAS, USMP, and many GAS and middeck payloads where either 
samples need to be returned for study or the entire system needs to be re-
turned for refurbishment.

4) Much Space Tranportation System hardware requires the Shuttle explicitly,
or one of the above attributes.  Spacelab and Spacehab, for example, require
the Shuttle for life support, power, and heat rejection.  Other hardware
elements requiring the Shuttle are the Spacelab pallets, the RMS, and
most middeck payloads.

5) The Titan IV's launch rate is very low.  It has flown six times since its
1989 debut, while the Shuttle has flown over 20.  All available Titan IVs 
for the near future will be used for launching Air Force payloads.  None are
available for NASA or commercial uses for quite some time.

Conclusion: Whether or not the cost of a Titan IV launch plus the cost of
DC-X is less than the cost of a Shuttle flight, the point is moot, since
nearly all Shuttle payloads require some aspect of the Shuttle that is unique
to the Shuttle.  For these five reasons, a Titan IV flight can not substitute
for a Shuttle flight.

Point 2: STS-52 could have flown on a $10 million Pegasus.

I have addressed this in another post, so I will just post the conclusion
here.

Conclusion:  Point 2 is simply not true.

Point 3:

>For what we have spent on Shuttle we could have built two Freedom
>space stations or about 20 or so Industrial Space Facilities. Utilization
>of either of these would be hundreds of times greater than Spacelab providing
>hundreds of times the chance to fly important experiments.

This is a highly speculative point, since it involves analyzing the politics
of the early and mid 70's, but it can on the surface be proven false for one
simple reason:

Space Station Freedom (or any reasonble space station) requires the Shuttle
to launch.

There are two things unique to the Shuttle that are required to build SSF.
The first is heavy-lift capability (relatively speaking, of course), and
the second is manned spaceflight.  Neither would have been available without
the Shuttle.  The Saturn V, the Mercury and Gemini capsules, and the Apollo
hardware were all already cancelled when the space shuttle came into being
in 1972.  They were NOT cancelled to fund the Shuttle.  In fact, the cancell-
ation had a large impact on the configuration of the Shuttle, as it had to
assume the roles of much of the cancelled hardware.

Without the Shuttle, there would be no heavy lift (even the Titan IV didn't
come into being until 1989) and no manned spaceflight.  Any space station
would require either one or the other (or both) to launch and assemble in
space.  There could be no SSF without the Shuttle, and since ISF requires
man-tended operations, there could be no ISF without the Shuttle either.

Conclusion: Since the Shuttle is a pre-requisite for SSF and ISF, neither
could be built at the expense of the Shuttle.  Point 3 is false.

There were (note past tense) alternatives.  Other hardware could have been 
built to meet the needs of heavy-lift and manned spaceflight.  This is where
the speculation comes in.  But whatever could have been built would have had
to face the same Nixon administration, the same OMB, and the same Congress
as the Shuttle did.  To say that any system able to meet the needs of heavy
lift and manned spaceflight would have had vastly different political accept-
ance in the early 70's, in my opinion, is pure speculation.

All speculation aside, we have TODAY a hardware mix that has useful capabil-
ities.  How we use those capabilites today and how we expand them tomorrow
are far more important issues than speculation on what might have been.

Mike

-- 
Michael Kent                                   kentm@rpi.edu
Flight Test Engineer                           Tute-Screwed Aero '92
McDonnell Douglas                              Rensselaer Polytechnic Institute
These views are solely those of the author.    Apple II Forever !!
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