From: email@example.com (Henry Spencer)
Subject: Re: Need for New Space Shuttle
Date: Thu, 14 Dec 1995 23:52:27 GMT
In article <firstname.lastname@example.org> email@example.com writes:
>>>could save much work and worry doing modular improvement and testing of
>>>a proven lunar vehicle.
>>The trouble is that the plans don't tell you everything. We can't
>>duplicate the CM or LM today; too many of the contractors are gone, and
>>the ones who are still around have long since forgotten just how they
>>built their bits. You've got to re-develop and re-test ...
>I see this written alot and I don't understand were it comes from. If
>the print doesn't have the info, in most cases The original article is
>still around. What is it that you can't find out?
How it was made. Metals are not simple substances; details of refining and
machining and heat treatment can have substantial effects on their final
properties. As a gross example, if you're trying to weld titanium, you
wash the parts with distilled water, not tap water, because the chlorine
in tap water can make the welds brittle. (Lockheed had trouble with this
exact problem on the Blackbird series.) This is the sort of thing that
often doesn't get written down. In some cases people don't *understand*
it well enough to write it down; for example, they may just know that the
material from plant X worked and the stuff from plant Y didn't (not an
imaginary example), which doesn't do you a whole lot of good when neither
plant exists any more.
>People rebuild old airplanes and Steam locomotives, the Simthsonian has a
>steam engine that was built in the 1830's that was rebuilt to run. I saw a
>P-38 that was nothing more then the wing out to the engines that was going
>to rebuilt using all the origanal extrustions even through that meant
>making the dies for them.
However, once it's rebuilt, you won't find people flying 5G turns in it.
The issue is not whether you can build something that's close enough to
work a little in forgiving conditions, because rocket hardware doesn't
have large safety margins.
> I would bet that any of the aerospace companies would fall all over
>themselves to get a multi year contract to provide Apollo era
Aerospace companies are always delighted to get cost-plus contracts for
>...sure you would have
>to retest but they flew the Saturn V manned on its third flight.
Yes, and that was a calculated risk; they nearly lost the eighth one
because of a bug that wasn't eliminated quite quickly enough and was
worse than people thought. (The crew of Apollo 13 was very lucky that
the center engine of their second stage shut down early, because it
was about to rip the stage apart with ferocious pogo oscillation.)
A realistic test program takes longer.
>And of course the electronics would be updated but so what?
For things like the control systems, unless you duplicate the old ones
exactly, you've got to re-run a lot of the analysis, simulation, and
testing. Almost all rockets are aerodynamically unstable vehicles, so the
wiring and software in their control systems is flight-critical. Being
compatible with the specs is not enough to be sure the behavior will be
the same; you have to reproduce the bugs too, because some of them may
have cancelled out mistakes elsewhere!
>If private industry is supposed to be capable of doing the job that Nasa
>does but only better why can't they meet standards laid down 30 years ago?
They can certainly develop a new vehicle, vaguely Apollo-like, for less
money than the original Apollo development budget... which was a lot.
You've missed the point; industry can do the job over again, but they
can't pick up where they left off, because some of the necessary
information isn't around any more. "When we dropped it, it broke."
Look, look, see Windows 95. Buy, lemmings, buy! | Henry Spencer
Pay no attention to that cliff ahead... | firstname.lastname@example.org
Subject: Re: Redesigning the CSM/LM for '97...
From: Henry Spencer <email@example.com>
Date: Fri, 7 Mar 1997 04:35:39 GMT
In article <firstname.lastname@example.org>,
>It's 1997. NASA has the hardware/time/money (and yes, blueprints!) to
>relaunch a series of Saturn V flights to the moon. It's going to be using
>the exact same design from the 60's....except there is the opportunity to
>redesign the CSM & LM. Anybody care to speculate on the improvements...
Actually, recent studies of return-to-the-Moon projects are informative
The first thing one would consider would be switching to direct flight
instead of Lunar Orbit Rendezvous. The LOR architecture really makes
sense only when surface stays are relatively brief and the flight is
dominated by transit time. When surface stays get longer -- as they
surely would in any new program -- the lander increasingly dominates the
payload, and the costs of leaving the return vehicle in orbit start to
outweigh the benefits.
Second, one would almost certainly switch to LOX/LH2 propulsion for the
outbound trip and the landing. The RL10 is throttlable enough to make a
good descent engine -- in fact, that's why it was qualified for really
deep throttling! -- and we're not scared of using LOX/LH2 for deep-space
propulsion the way people were in 1960. At the very least we'd use
pump-fed LOX/kerosene, but LOX/LH2 would probably be better. Propulsion
for the return trip might remain N2O4/hydrazine for long-term storage,
although high-energy oxidizers like ClF5 would be worth considering as
alternatives to N2O4.
Third, all the structures would be redone in composites.
Fourth, we would not overdesign certain areas -- notably the CM heatshield
and the LM legs -- nearly as greatly as Apollo did, because we have much
better information to base designs on.
Fifth, we would at least consider using solar arrays rather than fuel
cells for en-route power. We'd certainly use solar arrays for surface
power (the LM enhancements done for the later Apollo flights *almost*
included solar arrays).
And many other things would get lighter because of improved technology.
Electronics would be the obvious case, but not the only one.
We would *probably* also include one or more small teleoperated rovers,
to do chores like scouting around while the astronauts sleep or do other
It should be possible to do a ten-day surface stay with a crew of 3-4
using a single Saturn V. Maybe more, although the lunar night presents
some problems. We'd also think about multiple launches per mission -- a
cargo lander followed by a manned one -- which is an approach Apollo would
also have pursued had it been continued.
>...Modern day lunar suits, would be much lighter, and capable.
Actually, spacesuit technology is one area that has improved hardly at
all. We'd basically reinvent the Apollo suits with various marginal
improvements. (The shuttle suits are impractical for lunar-surface use --
they are too heavy and are not balanced properly for walking.)
Committees do harm merely by existing. | Henry Spencer
-- Freeman Dyson | email@example.com