In article m,
says...

Brian Gaff wrote:
Actually, the Shuttle was only a problem because they put cargo and people
in one lump.


Without the shuttle, how would experience on operation of robotic arms
have been gained ?

Hard to tell, but I'd say that the arm(s) would have been attached to
the space station and/or the orbital maneuvering vehicle instead.
Keeping the arm(s) in orbit, where they're useful, is arguably better
than launching them again and again on each and every flight.

Without robotic arms, we'd still be stuck with tiny hatches like the
russians, no CBM. And that means no HTV or Dragon abilities to send and
remove large objects from station. Without arms, no ability to really
assemble a space structure such as the truss, large scale solar panels etc.

Again, this is more of a function of the station design than the design
of the shuttle. Note that HTV launches on an ELV and berths with a CBM
via the station robotic arm. No shuttle arm is necessary for this to
happen.

The experience gained from the shuttle operation is invaluable. It is
that experience that allowed the canadarm2 to be build for the station.
(and that experience which allowed the software to run the arms to be
greatly improved over the years).

The experience is "invaluable", but the shuttle was not the only way to
gain that experience.

The shuttle also thought lessons on how to really design a reusable ship
to make sure maintenance betwene trips can be done easily. And it tought
serious management lessons about safety.

I'd argue it taught us more about what *not* to do in this area. Large
segmented SRB's are costly to reuse, vibrate more than liquids, and have
catastrophic failure modes. Toxic hypergolic propellants complicate
ground workflows and pose risks to crews and payloads in orbit. Fragile
TPS ought not to be used on a vehicle attached to the side of a tank
which has spray on external insulation. LH2 poses processing issues and
leaks are *hard* to find, especially in a cramped compartment which is
hard to access.

The list goes on, but everyone gets the point.

I wouldn't mind the loss of the Shuttle if it were replaced by something
just as capable. But it isn't being replaced. Instead of having a solid
construction truck, all that is left are dumb delivery trucks
(Progress, Dragon, ATV, HTV) and tiny telephone booths (Soyuz) without
any ability to built/assemble structures in space.

I'd argue that we *don't* need something "just as capable", because much
of that capability is "nice to have", but not "necessary to have".
Paying a premium for functionality that is "nice to have" isn't a smart
thing to do.

Jeff
--
"the perennial claim that hypersonic airbreathing propulsion would
magically make space launch cheaper is nonsense -- LOX is much cheaper
than advanced airbreathing engines, and so are the tanks to put it in
and the extra thrust to carry it." - Henry Spencer