Re: should space shuttle be cancelled?

On Sun, 07 Aug 2005 17:31:48 GMT, Joann Evans
<bondage@xxxxxxxxxxxxxxx> wrote:

> Um, an SRB failure that leads to destruction of the ET and an orbiter
>wing, will destroy vehicle symmetry, yes....

Yes, where it was that last step in the process that killed them.

>> No. Columbia survived for several days in this damaged state.
>
> So the fact that it didn't destroy Columbia immediately during
>ascent, changes my point...how?

If they had been previously aware of this possible problem, and had
taken prior steps, then the Columbia crew may have lived on. So it was
not the foam that directly killed them, but the dangerous process of
reentry that does not tolerate faults.

> The Titanic remained afloat for hours as well, but doesn't change the
>fact that the process began with an iceberg collision.

Certainly. And had they adequate lifeboats, then all the passengers
could have lived on. So it was the environment of the cold ocean is
what really killed them.

> No additional environmental factors need be invoked to accept that a
>foam strike damaged TPS material on a wing leading edge. An orbiter is
>always presumed to eventually land.

Then had Columbia spent it's life in orbit, then this hole would not
have been a concern. So it is easy to conclude that the environment of
reentry is a lot more dangerous than the environment in LEO.

> Pressures and tempratures acting on a portion of the structure that
>was compromised by a foam strike.

And had an aircraft wing suffered the same damage, then the odds are
that the aircraft could have landed safely. In fact it may have
continue on not even aware that there was a problem.

So proof enough that the reentry environment is a lot more dangerous
than the normal environment for flight. Therefore, additional safety
concerns need to be considered, when dealing with this more hostile
environment.

> And even bird strikes sometimes bring down otherwise functioal
>aircraft, typically in the process of takeoff/climbout, where things are
>somewhat more 'critical' than straight and level flight at cruise
>altitude.

On my return to London in the UK from Gothenburg in Sweden the
aircraft I was in, during landing, sucked up a bird. This aircraft
design, already aware of this problem, proceeded to initiate an
automatic process, where the engines where revved for a couple of
seconds in order to clear out the debris.

In other words aircraft can now handle this situation.

>But we don't refer to that period as an 'extreme environment.'

Birds are a part of this environment. The problem has been solved in a
way that does not benefit the birds. You could also label this under
one of your "being attacked by outside forces".

Mostly all aircraft who hit birds survive, when this problem has been
solved in the design.

> And Columbia underwent nothing unusual or unknown 'environmentally'

Mach 16+. Large G-Forces. Extreme friction. To name a few. Aircraft do
not have these "environmental concerns" to worry about.

>that its design could not normally handle.

On a knife-edge. This goes to show what one small hole can do.

> Of course, you can argue that vibration/acceleration causes all foam
>detachment...how does that translate to designs that aren't stacked
>paralell, or use no ET?

NASA is just being crazy. They could certainly solve this foam problem
quickly and cheaply in just a few weeks. The reason why they do not do
so is because this would increase the mass of the ET.

Since NASA spends a lot of it's time removing mass from the ET, then
they don't want to put it back on again. As had they done so, then the
shuttle launching some of those ISS components would not even make it
into the ISS orbit.

So other people's designs do not have to deal with a shuttle that is
largely over the design weight due to previous safety upgrades.

NASA's best option is to launch and install the most heavy ISS
components, then to do a *real* fix of this foam problem.

Also just what are they doing launching a 10 ton cargo module that can
carry 3 tons of cargo? Sounds like someone screwed up that design,
when 10 tons of cargo in a 3 ton module sounds a whole lot better.

Maybe in the future NASA should stick to packing supplies into their
lighter ISS components, when their Italian build cargo module is a fat
ugly pig.

>> Well, they could certainly have done something. The extra mass
>> involved is why they have not.
>
>Which matters, if you indend to carry signifigant cargo.

If they really want to launch large cargo in the future, then NASA
really does need to upgrade their engines. Maybe to enlarge their SRB
size a bit, or to add on some mini-SRBs.

Had they done that, then they could both do a "real" foam fix, and to
get their large cargo mass into orbit. Removing further mass from the
ET is simply not an option, when they now need to add mass back on.

Their failure to solve this foam problem, despite the $200 million
spent on it, clearly highlights that they are barking up the wrong
tree. Foam will always fall off simply because it is foam. And them
trying to work out why the foam falls off, is simply a case of trying
to understand an unsolvable problem.

So the only solution is increased thrust on launch.

>> > I prefer a vehicle robust enough that it's no more likely to have a
>> >catastropic failure than a commercial aircraft.
>>
>> You seem very blind today. No space launch system has ever come close
>> to modern commercial airline travel.
>
> None flown so far.

Certainly. And that explains my point of why they need to consider
additional safety steps. They have not yet mastered this environment
by a long way.

>And make not the assumption that if it could be done, NASA would already
>be doing it.

Fair enough.

>Even the current shuttle design is not what NASA originally wanted. Politics
>and funding were as much a factor as engineering.

Yes, but NASA is also responsible. They accepted it and they had it
built.

>> Since the two simply cannot compare,
>
> Now and forever?

In the future, it seems highly likely, that they could do safe designs
that deal with all safety considerations.

> The definition of 'dangerous environment' is subject to debate. All
>air travel could once have been described as such.

Yes, it would have been. NASA is a long way behind that of aircraft
dealing with flight. They even make better ships these days.

>> All NASA's plans to date involve manned vehicles that require launch
>> and reentry. Those are the more dangerous areas, but I am sure that
>> given time NASA will also find something in your safe space to kill
>> their astronauts as well.
>
> You seem to assume that operating in those regimes inherently can
>never be made as safe as commercial aircraft operations, in *any*
>launcher design. I do not.

No, I am simply saying that it won't be nearly as safe any time in the
near future. I am already sure that their CEV will go on to kill their
astronauts.

The CEV will be like 100 times better than the shuttle, but 1000 times
less safe than commercial aircraft travel.

You also have to accept the serious future problem of lack of fuel. Or
more correctly at the current time they only get places by "drifting"
there, through minimal fuel use.

So in the future you just have to accept the fact that if one of their
CEV's goes flying out of orbit, in the wrong direction, then they
simply won't be getting them back. There are some missions that they
simply cannot do within the allowed time limit.

>> We do not yet have the technology to make a safe design.
>
> Or perhaps no one (espically NASA) has seriously tried?

First they have to learn how.

One other problem is that; the further NASA goes in their exploration
plans, the more hostile the environment will get. The heat around
Mercury, the high pressure and acid rain on Venus, dust issues and
solar storms on the Moon and Mars, the radiation belts of Jupiter,
etc.

I am also sure that there are tons more space concerns that I have not
listed.

Once some bright spark solves all these problems, in an efficient
light-weight design, then you have your system as safe as commercial
air travel.

My point here is that since NASA is all onwards and upwards, then you
simply won't get your safe design any time soon. It may even get worse
some time in the future.

>Which, I submit, says more about the designs, than the environment.

The design does not deal well with the environment. And for NASA that
will not change any time soon. You can use the MPL and MCO as examples
of how well NASA will do their CEV "parking" in the future.

>> I have yet to see a vehicle design that would not kill some of the
>> people who ride it.
>
> Of course. I'm sure that 'some' people have died in the same
>make/model of car that I drive. Despite one spectacular fatal accident
>(arguably caused by the 'outside force' of runway debris),

Vehicle safety does need to accept human failings. This is why cars
now come with airbags, roll bars and side-impact bars.

NASA won't be building such concepts into their CEV.

>even the
>Concorde had a very good safety record, by commercial standards, yet it
>functioned every day in the same Mach 2+ regime that was strictly the
>realm of relatively fragile rocket powered X-planes, decades ago.

That it did.

>(Concorde ultimately failed *commercially,* but that's another debate
>for another time. Everyone who boarded one, could assume they'd safely
>step off at the other end.)

Concorde was never really built to be that commercial, due to it's
high fuel use and limited passengers. Built by the French and the UK
governments. It was handed down when the airlines moved out of
government control and kept on as a status symbol.

Commercial reality eventually won out.

> The point is, there's no inherent reason that human access to LEO
>can't be brought up to a safety level close to those things we think of
>as common risks today.

Given another 200 years then maybe so.

> But no, they aren't going to be shuttle orbiters, any more than
>British Airways and Air France flew people in something like the X-2.
>
> But they will learn the *lessons* of those earlier vehicles....

And the whole point of this is that the CEV won't be this perfect
vehicle. It will be a great deal safer than the shuttle in doing all
those same tasks, but this will be partly offset with additional risk
now that NASA is sending it places where the shuttle has never gone.

Cardman.
.