Jay Masino wrote:

JohnMcGrew wrote:
Blame it on NASA. If there is a lack of alternative "heavy lift" capability,
it's only because over 20 years ago, NASA mandated that all future government
payloads be designed around the shuttle, and all alternatives to the shuttle be
scuttled. This was in order to make the shuttle a "necessity" to America's
space program.

That's interesting, since NASA routinely sends payloads into orbit on
spacecraft other than the shuttle. The three that I work on (EOS/Terra,
EOS/Aqua, EOS/Aura) are all non-shuttle payloads. If I remember right,
Terra and Aqua were launched using Atlas Centaur rockets, launched from
Vandenburg AFB in California.

That's true, ....today. But by the 80s (hence the 20 years ago) NASA (and the
government at large) did mandate that the shuttle would be the platform for all
government launches, including military. In addition, the shuttle was supposed to
somehow make money with commercial launches for private satellites in the USA, and
the rest of the world too. Production was being terminated for Delta, Atlas, and
Titan rockets.

The design of the shuttle itself reflects this. Remember, the shuttle design had at
least as much to do with politics as it did with aerodynamics. In a post Apollo era
of massive cutbacks, the shuttle need the DoD's support and funding to get approval
by the Nixon administration. To win DoD (Air Force, mainly) support, the cargo bay
was built to handle large DoD satellites. The wing design was much larger than what
would be optimum for NASA.

Why? Because all government launches included polar orbit launches, which were to be
launched from Vandenberg AFB. The larger wings were needed for the cross range
needed to allow the Shuttle to glide back to Vandenberg (or somewhere else
convenient) in case an engine was lost prior to orbit insertion. Also, DoD payloads
had very wide measurements. The compromises needed to support the DoD greatly added
to the weight of the orbiter. A planned booster engine, which was supposed to
provide a one time go-around capability, had to be deleted early on because of these
constraints.

In addition, and no less importantly, the larger wing design necessitated a much
larger thermal cross section in reentry, and also meant the orbiter would be spending
much more time in the hottest area of reentry. The tile system was created to meet
this requirements. It is ironic that the design constraints not used for today's
shuttle are what help to make the shuttle so dangerous.

The shuttle would be used for higher altitude (and deep space probe) launches too.
How would it do this? Two orbiters, Discovery and Challenger were modified to
support the Centaur upper stage, which is a liquid fuel rocket. Ports were added to
the orbiters to allow the Centaur to be fueled and vented, plus the necessary
controls. Centaur never flew on the shuttle. After Challenger's accident NASA
reevaluated the wisdom of liquid rockets in the cargo bay.

[TANGENT: The recently demised Galileo probe to Jupiter was originally designed to
use the shuttle / Centaur, and after shuttle flights resumed post-Challenger
accident, it had no method of launch available. (The revived non shuttle launch
program had not been cranked up again yet to support it). So it was launched from
the Shuttle, but Venus, Venus (again) and Earth's gravity was used to get the probe
to Jupiter in an ingenious roundabout route. After launch the high gain antenna
never deployed, possibly because it was in unplanned storage for so long while
Shuttles was grounded. The low gain antenna saved the day after new compression
software was uploaded to the probe and the entire Deep Space Network was configured
to talk to Galileo.]

By the mid 80's the shuttle program was getting out of control. The schedule was
getting increasingly crammed on the now-declared-operational shuttle. To get enough
launch revenue (this made sense to somebody in government fantasyland), launches were
to be increased to once a month, and then nearly every two weeks (24 per year). But
there were only enough parts for two shuttles. Remember, Challenger's 51L launch was
delayed to that cold January morning partly because Columbia's prior 61-C launch was
delayed about a month, and parts needed to be flown (via a T-38 IIRC) from the
Columbia to Challenger. Columbia's landing was also delayed, due to weather, and it
was not able to land at KSC, as originally planned. The ripple effects of one delay
in this tight environment could affect the entire launch schedule for 12 months, or
more. Every time an orbiter was cannibalized for parts, the risks increased due to
exposing them to possible servicing problems.

In the end, the shuttle just wouldn't be able to perform at Vandenberg, despite the
changes that were made to its initial design for polar launches there. Unlike
launches from KSC, Vandenberg polar launches would not benefit from the earth's
rotation. KSC launches go in orbit, aided by the boost of the earth spinning to get
the craft up to orbit speed. But Polar launches are roughly perpendicular to the
earth's rotation, so there is no boost at all. This means that much more power is
needed from the engines.

An attempt was supposed to be made to develop a lighter solid rocket booster design,
but the Challenger accident cut all of this short. After the accident, the Vandenberg
shuttle launch facility was mothballed. Only then was the Titan IV (Martin
Marietta-now Lockheed Martin) program begun to launch big DoD payloads (and the NASA
Cassini spacecraft, due at Saturn on July 4 2004.). The DoD/NASA finally realized
that expendable rockets really would be needed, shuttle or no shuttle. Also, NASA
got out of the commercial and DoD launch operation business a few years after the
Challenger accident. The manufacturers and the USAF took this over.

By the way, at Vandenberg, huge structures had been created to shield the orbiter's
new pad from prying eyes during DoD missions. Support and vehicle assembly buildings
were constructed, and a runway was lengthened to support orbiter landings. Even a
seaport was constructed. Vandenberg's first space shuttle launch was to occur mere
months after 51-L landed safely. The launch area, SLC-6 or "slick 6" was dogged by
poor workmanship and allegations of drug use by construction workers. It was rebuilt
to launch Athena, and now Delta IV (Boeing) rockets.

By the way, a decision was made to make a set of "structural spares" of large
fuselage and tail parts (vertical stabilizer, rudder, wings, elevons, etc) during the
construction of Discovery and Atlantis, to repair a fuselage in case there was
accident damage. These spares would later be used to build Endeavour. The
Challenger accident occurred just before shuttle production facilities were to be
ramped down. Also the later shuttles (Discovery, Atlantis, Endeavour) have much
fewer thermal tiles, because advances in material technology allowed more thermal
blankets on the upper fuselage instead.


The reality was that the economics of the shuttle were complete fantasy, and
NASA knew it. (hence the mandates leaving the US with few alternatives until
the French, Russians, and Chinese started filling the void) We could (and
perhaps should have) gone on building disposable Saturn-like boosters (500k
pound payloads, vs the shuttle's 30k to 40k). The R&D was paid for, and the
support costs would be a fraction. (A typical shuttle mission costs somewhere
around half-a-billion)

The Shuttle's purpose was more than just lifting payloads. It's both a
scientific platform, as well as a on-orbit repair station.

That's true, but the design limitations of the shuttle were based on launching
military payloads, most of which never launched on the shuttle, and never will.