So *was* Hubble maintenance cancelled because of the moon plan?

In article ,
Dick Morris wrote:

G EddieA95 wrote:

Enormous amounts of costly, complicated equipment are required to get
you to 35,000 feet in a 747. You wouldn't last very long there either.

But it is not scrapped after each use, and that keeps the "inherent cost"
down.
If we return to the Apollo capsule, I for one believe that what
improvements
exist since 1969 in access to space, will vanish.

An Apollo CM derivative, or look-alike, could certainly be made
reusable. It could also be launched on a reusable vehicle.

The improvements are vanishingly small already. The Shuttle is more
expensive, and probably less reliable, than what we had back then.

One of the reasons the shuttle was more expensive was because it was
expected to be able to do more. It could accommodate a crew of 10 in
more comfort than an Apollo CM. It could also carry a more substantial
payload into LEO than an Apollo CM, although not as much as a Saturn V,
of course.

Another reason was its reuseability. For example, it did not need to
have its heatshield completely replaced after every mission, as would
probably have had to be done had anyone attempted to reuse an Apollo CM.

Had NASA attempted to engineer an Apollo CM to last as long as a shuttle
was expected to last its cost would doubtless have shot up too.

As for reliability....

Well, the figures speak for themselves. There have been over 100 shuttle
flights over 20 years with two losses. If you count Apollo 1, Apollo had
loss and one near-loss (Apollo 13) over a period of six years. The
shuttle has lost two over 20 years.

More lives have certainly been lost overall with the shuttle, but mainly
because the shuttle carried more people. Had Apollo carried a crew of
seven, seven lives would have been lost in the Apollo 1 fire and seven
would have been held in the balance on Apollo 13.

That said, the shuttle is probably the more *dangerous* to fly, in part
because of those sold-rocket boosters. Once they're lit either they take
you into orbit or they go BOOM. They cannot be shut off. There is also
nothing equivalent to Apollo's escape tower.

But that I guess was the trade off NASA made to launch something the
size of the shuttle orbiter into orbit. What NASA should have done was
to either make the entire crew compartment ejectable or have the crew
ride into orbit in part of it that was. But that, of course, would have
only increased the complexity of the shuttle and therefore its cost.

In any case, in the longer term there may well be no real solution so
long as rockets are used to launch people into orbit. People forget, for
example, that if a Boeing 747 were to blow up or disintegrate in
mid-air, there would almost certainly be no survivors either. If ever
NASA or anybody else starts launching 100 or 200 people into orbit in
one vehicle the same will doubtless apply.

--
Stephen Souter

http://www.edfac.usyd.edu.au/staff/souters/

"Stephen Souter" wrote in message
...

That said, the shuttle is probably the more *dangerous* to fly, in part
because of those sold-rocket boosters. Once they're lit either they take
you into orbit or they go BOOM. They cannot be shut off.

I thought there was a long pyro string down the side of the casing that
would basically "open up" the entire SRB, the point of which would be to
rapidly (i.e. within ten seconds) zero out the thrust...

--
Terrell Miller


"It's one thing to burn down the **** house and another thing entirely to
install plumbing"
-PJ O'Rourke

"Terrell Miller" wrote in
:

"Stephen Souter" wrote in message
...

That said, the shuttle is probably the more *dangerous* to fly, in part
because of those sold-rocket boosters. Once they're lit either they take
you into orbit or they go BOOM. They cannot be shut off.

I thought there was a long pyro string down the side of the casing that
would basically "open up" the entire SRB, the point of which would be to
rapidly (i.e. within ten seconds) zero out the thrust...

Yes, the Range Safety Destruct (RSD) packages. However, they would also
have the effect of rupturing the external tank, and destroying the orbiter.
The purpose of RSD is to protect innocent third parties on the ground, not
the crew.


--
JRF

Reply-to address spam-proofed - to reply by E-mail,
check "Organization" (I am not assimilated) and
think one step ahead of IBM.

In article ,
Terrell Miller wrote:
because of those sold-rocket boosters. Once they're lit either they take
you into orbit or they go BOOM. They cannot be shut off.

I thought there was a long pyro string down the side of the casing that
would basically "open up" the entire SRB, the point of which would be to
rapidly (i.e. within ten seconds) zero out the thrust...

Approximately correct. Unfortunately, this isn't a gentle, gradual event.
When you fire that shaped charge, it slices the SRB casing open, i.e. it
destroys the structural integrity of a very large pressure vessel. The
result is **!!KABOOM!!** with pieces of SRB casing and flaming fuel flying
everywhere a fraction of a second later.

If you do this with the stack still together, it's virtually certain to
destroy the ET as well. (Which is why there are no longer destruct
charges on the ET.) And if the orbiter hasn't already broken up, that will
almost certainly throw it violently out of control, and *that* will break
it up... which is what happened to Challenger after its ET disintegrated.

This is a destruct system, not just a way of shutting the SRBs down.

There *are* somewhat less drastic ways of terminating thrust of a solid
motor. Unfortunately, they are only *somewhat* less drastic; using them
is still a fairly violent event. NASA chose solid boosters for the
shuttle on the assumption that SRB thrust termination was feasible... but
later engineering analysis said that the orbiter and ET wouldn't survive.
--
MOST launched 30 June; science observations running | Henry Spencer
since Oct; first surprises seen; papers pending. |