From: Technotranscendence (neptune@mars.superlink.net)
Date: Sat Feb 01 2003 - 12:06:54 MST
On Saturday, February 01, 2003 1:27 PM Adrian Tymes wingcat@pacbell.net
wrote:
>> All the shuttles, IIRC, have been upgrade
>> several times. Just recently -- was it 2000?
>> -- Columbia was overhauled. Last year,
>> too, cracks were found in fuel lines. I forget
>> what was done with these.
>
> Some things have been modernized, mainly
> the electronics. The shuttles are still,
> fundamentally, aging machines that are ever
> more expensive to maintain and operate. They
> needed to have been replaced a long time
> ago. Stuff like this will happen again if NASA
> maintains its present course, instead of actually
> funding replacements* for the space shuttle
> - and cutting off contractors that have failed
> in that project before and have every financial
> reason to fail again if it'll sop up all of NASA's
> resources on that project.
Part of this is just that NASA is run politically. The Shuttle program,
in particular, is so focused on reusability that efficiency falls by the
wayside. (Okay, I'm ready for a certain rocket engineer to chime in
with "you don't throw away a 747 everytime you fly it." If the cost of
maintaining the plane after one flight were more than building a new, I
would. Throwaway Saturn Vs would probably be more efficient and maybe
even safer than the Shuttles.)
> * Replacements cheap enough to operate that
> they can be tested to the point of failure so the
> rest of the fleet can, financially, be retired (and
> replaced) before it gets there. (Doesn't matter
> if it's physically/technologically possible; it simply
> won't happen if it costs way too much.)
It's not just that, but also the culture at NASA. It's slowly changing,
but it seems focused on a certain type of conservatism.
> BTW, don't accuse me of being insensitive here.
It's not insensitive to discuss these issues openly. I think all of us
feel some loss here. This does not mean we shut off our brains.
> One of the mission specialists was a personal
> friend of my dad, and I had to comfort him.
> Angry that NASA's mismanagement of
> replacement programs has allowed this
> malfunction to happen, perhaps, but not
> insensitive.
I'm not so sure, but I tend to side with you here. We have to get the
facts in first to see what happened and why before judging this
particular tragedy.
BTW, I posted this on Starship Forum
http://groups.yahoo.com/group/Starship_Forum/ ) earlier this week. I
thought it might be of interest to some on this list.
_______________
From: Technotranscendence <neptune@mars.superlink.net>
To: Starship Forum <Starship_Forum@yahoogroups.com>
Sent: Thursday, January 30, 2003 6:00 PM
Subject: [Starship_Forum] Rocket engine performance
A few days ago, SpaceDaily.com reported that "Ion Engine Prototype
Passes 18000 Hours Of Autonomous Operation."
http://www.spacedaily.com/news/rocketscience-03b.html
] This brings to mind a problem that will have to be solved for long
duration missions and space settlement: long-term performance of rocket
engines.
There are three not so radical solutions I can conceive to this problem.
One is to design engines that are more reliable and have better
long-term performance, including being able to start and stop frequently
as well as remain active and inactive for long periods without a
noticeable degradation in performation. This is the Rolls-Royce
approach, though the name shouldn't make it sound expensive. The goal
is to produce an overall excellent engine.
I can imagine such engines being tested just like the Japanese ion
thruster above -- set to run and run and run. (In fact, part of the
design process could be to just take an existing prototype, running it
for a long time until it fails, then creating a better prototype to
account for the failure(s), and repeating the process. This incremental
approach might work.)
Another is to come up with maintenance and repair processes for engines
so that degradation in performance can be corrected. This is kind of
the Oil Change approach -- keep it well maintained and fix any problems
to extend equipment life span.
Such engines would either have to be designed for easy maintenance and
repair or [an inclusive "or"] maintenance and repair methods will have
to be designed to make this work.
A third approach is to make cheap modular engines -- the "Throw Away"
approach -- that can be pulled when they degrade. This can be extended
to cheap throw away propulsion systems -- where the whole propulsion
system is replaced when it starts to degrade.
Conceptually, this is simpler and might allow for a variety of
propulsion systems if modularity is taken to an extreme. One could
imagine a spacecraft that can be mated to any sort of standard plug in
propulsion system -- be it chemical, ion, nuclear electric, or something
else -- if object-oriented design is observed.
This same sort of logic -- Rolls-Royce vs. Oil Change vs. Throw Away can
be applied to all other spacecraft systems, such as life support, waste
management, power supply, heating/cooling, information systems, and
communications. No doubt, all three approaches will be used. I can
imagine, especially, wanting life support and power systems to be more
like Rolls-Royces, while propulsion in some cases being Oil Change, and
many other minor systems being Throw Aways. No doubt, the mix will be
different depending on a host of factors, inlcuding how well established
trade is (the spectrum can run from highly integrated to autarkic).
What do you think?
_______________
BTW, earlier, I was mistaken about astronaut Ilan Ramon's parents. It
was, from what I've now heard, his grandmother who was a survivor of a
concentration camp.
In memory of all pioneers who lost their lives pushing back the
darkness,
Dan
http://uweb.superlink.net/neptune/
See "Splitting Hares" at:
http://uweb.superlink.net/neptune/SplittingHares.html
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