Date: Tue, 4 Feb 86 22:26:32 EST
Subject: Galileo, Plutonium, Centaur, physical security [4 messages combined]
[Re Marty Schoffstall, on plutonium batteries for pacemakers and satellites:]
Note that the Soviet satellites use reactors, not isotope capsules, as
their power sources. The two are quite different, especially in this
context. It's not practical to encapsulate a reactor the way the isotope
capsules are armored against possible accidents.
[Re Larry Shilkoff, on Galileo:]
The capsules used to hold plutonium 238 (note that this is not the
fissionable isotope used in reactors and bombs) for deep-space power
sources are designed to withstand uncontrolled re-entry, and I think
to withstand launch accidents as well. Quite likely they would have
survived intact. There have been a few re-entries of satellites carrying
such capsules, and one went into the Pacific with the lunar module of
Apollo 13. No dire results.
[Re James Tomayko, on Centaur aboard shuttle:]
Apart from the volatility, this is nothing new: major solid-fuel motors
routinely ride in the cargo bay. Those things are dangerous too. People
doing some of the amateur-satellite work have estimated that the paperwork
needed to clear a satellite for a ride in the shuttle cargo bay roughly
triples if it is carrying any substantial rocket motor, solid or liquid.
> Worse yet, Galileo was to be the
> <first> user of the new upperstage, which shares little with its predecessor
> except the name. It has new tanks, engines, and instrumentation...
Not quite true: the Ulysses solar-polar mission, using the same upper
stage, was to launch about a week before Galileo. Still awfully tight.
> [in an abort] what are the dangers of trying to land with a full load of
> hydrogen and radioactive isotopes? ...
Actually, although the liquid hydrogen is what everyone points at, the
liquid oxygen is probably the greater danger. "Stages to Saturn", the NASA
history of the Saturn boosters, commented that liquid hydrogen hazards were
found to be comparable to those of highly-volatile gasoline (not trivial,
mind you!), while it was liquid oxygen that really needed extraordinary
[Re: Jeff Siegal on NASA/KSC physical security:]
It's not conspicuous, but it's there. Practically nothing is said about
it in public. I was down at the Cape for the 41C launch, on the National
Space Institute tour. We got (I think) a slightly closer look at things
than the ordinary KSC tours, but when we went past the actual active pad
a day or two before launch we were cautioned that (a) the bus could slow
down but it must not stop, and (b) all windows, including the driver's
little vent window, must stay 100% shut. With a strong indication that
we were being watched and our NASA guide would be in deep guano if either
rule was violated even momentarily. We went past some press folks setting
up cameras, and our guide commented "if you're wondering why they're allowed
out of their bus and you aren't, it's because they've been searched and you
haven't". The pad area proper also has an impressive concentration of
things like concertina wire (think of it as industrial-strength barbed wire)
around its perimeter. It's difficult for a non-professional to evaluate
the quality of the precautions, but they did seem to be taking it seriously.
I have since heard a rumor that there were some awkward and hushed-up
incidents quite early in the Shuttle program that caused considerable
tightening of the original fairly loose security.
Henry Spencer @ U of Toronto Zoology
[We may be approaching the point of no return on some of the second-
and third-order discussion. PGN]