The Shuttle just gets worse with thought (was Launch cost thought experiment)

--- In spacesettlers 10978, ANTIcarrot wrote:
> I find myself wondering if the cost of cargo launch (once
> you remove the $1.5B operations costs) is close to $50/lb -
> which is what NASA always claimed it would be. :)

There are myriad reasons why the economics of the Space Shuttle
cannot improve with scale. Some are discussed here:
http://www.google.com/search?q=space+shuttle+garwin

"If one considers scaling the propulsion system of the shut-
tle for an expendable launcher, the "large external tank"
containing liquid hydrogen and liquid oxygen would be five
times smaller (and use five times less hydrogen and oxygen),
and the expendable boosters would be five times smaller (and
use five times less solid fuel). No matter how many times
the solid-rocket boosters (SRB) are to be reused in the ac-
tual shuttle, each use expends five times the fuel required
to launch the same payload on an expendable. And each use
incurs costs of returning the rockets to the factory, in-
specting and refurbishing, and the like.

But the deficiencies of the shuttle have not yet been fully
enumerated. Another aspect is the much more severe payload
loss due to "earth rotation" in the case of the shuttle. A
near-equatorial launch site allows a greater payload into
LEO than would be the case from a stationary earth, because
the eastward velocity of the earth's surface,
VE(&lambda.) = (40,000/86,400) cos&lambda. km/s
need not be supplied by rocket propulsion. This amounts to
some 0.4 km/s at Cape Canaveral, Florida.

[...]

For the shuttle, however, this same fraction of reduction of
mass to orbit applies now not to the payload but to the
gross or total mass into orbit, and the payload reduction is
not 13% of 65,000 lb (8400 lb) but 13% of 300,000 lb, or
39,000 lb. A 13% loss of payload for an expendable booster
becomes a 60% loss of payload for the shuttle into polar or-
bit.

Indeed, the shuttle normally launches into orbits of very
low altitude above the surface of the earth. The shuttle
suffers severe penalties if it is to carry a payload into a
higher orbit (hence longer life against atmospheric drag)."

Here are some Shuttle Orbiter numbers:
http://en.wikipedia.org/wiki/Space_Shuttle_Orbiter

Empty Weight: 151,205 lbs (68,586.6 kg)
Gross Liftoff Weight: 240,000 lbs (109,000 kg)
Maximum Payload: 55,250 lb (25,061.4 kg)

Listed payload is less on the main wiki Shuttle page:
http://en.wikipedia.org/wiki/Space_Shuttle

Payload to LEO 24,400 kg (53,600 lb)
Mass 2,029,203 kg (4,474,574 lb)

If the Orbiter gets into orbit nearly empty (in terms of fuel), save
for 53,600 lb of payload, the payload only represents 53,600 /
(53,600 + 151,205) = 26% of the mass delivered to LEO. Garwin, in his
comments at the link above, estimated 20%, but his basic theses still
apply.

The marginal launch costs (with 50,000 lb of payload) are supposedly
only $60 million -- or $1,200/lb (compared to the total program cost
of $1.3 billion per launch -- or $26,000/lb).
http://en.wikipedia.org/wiki/Space_Shuttle_program#Costs

"Early cost estimates of $118 per pound ($260/kg) of payload were
based on marginal or incremental launch costs, and based on 1972
dollars and assuming a 65,000 pound (30,000 kg) payload capacity.
Correcting for inflation, this equates to roughly $36 million
incremental per launch costs."

One bottom line is that (because the Orbiter weighs so much and
because the Shuttle as a whole costs so much to refurbish after each
use) it cannot cost appreciably less to launch the Orbiter empty,
rather than full, of payload. Another bottom line is that -- since if
NASA were capable of launching the Shuttle once-per-week, it would
almost certainly have been doing so all along -- we should consider
the marginal launch cost to be $1.3 billion, rather than $60 million -
- and further therefore we should consider the best-case (full
payload capacity) cost per pound to be $26,000.