"Brian Gaff" wrote in message ...
There seem to be so many contradicting views about the reason the Shuttle is
so costly, and its hard to get through the 'noise' in all the camps with
opinions, but not many facts.
....
The big question is, is it actually cheaper to make expendable launchers,
even when you are throwing a lot of stuff away, to end its days as scrap or
burnt up or at the bottom of the sea?


Study after study has shown that the answer is "It depends".
It depends mostly on the launch rate. If the launch rate is
low (the threshold is usually determined to be less than a
few dozen launches per year - but it depends on the specific
vehicle design), than it is cheaper to fly expendables.
Reusable vehicles only pay off if the launch rate is high
enough for expendable hardware costs to exceed reusable
refurbishment costs. Historically, launch rates have never
exceeded the payoff threshold for a specific vehicle - although
the Soviets may have come close during the 1980s when they
launched close to 60 Soyuz/Molniya rockets per year.

Why is it less than cost effective to reuse the boosters of the Shuttle?


Because the shuttle flight rate is below the break-even
threshold. The booster casings have to be recovered, towed,
cleaned, dissasembled, stripped of residual propellant and
insulation, tested, measured, and shipped again. A new
casing, by comparison, simply has to be manufactured, tested,
and shipped.


Also, what about environmental effects of dumping junk in various parts of
the world in this manner?


Sunken shipping (and aircraft for that matter) out-mass the
stuff that has/will reenter from space so extremely much that
the space stuff is practically irrelevant. Some of that
sunken shipping (submarines) took nuclear reactors and
thermonuclear warheads down to the bottom of several oceans.

- Ed Kyle