ARMS-D-Request@MIT-MC.ARPA (Moderator) (11/14/85)
Arms-Discussion Digest Wednesday, November 13, 1985 6:08PM
Volume 5, Issue 19
Today's Topics:
The REAL reason the Russians are afraid of Star Wars
VMOS instead of krytrons?
Re: VMOS instead of krytrons
UN saved us in 1962?
Semiconductors in radiation environments
proscriptive assumptions
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Date: Mon, 11 Nov 85 10:09:43 est
From: David Rogers <drogers%farg.umich.csnet@CSNET-RELAY.ARPA>
Subject: The REAL reason the Russians are afraid of Star Wars
On the MacNeil-Lehrer Report a few weeks back, a "Star Wars" panel discussed
why the Russian were afraid of the program even if their advisors counsel
them that it won't work as advertised. I was surprised that both the
proponents and opponents of the program agreed that the real reason they
feared massive research is that it would give US military technology a
huge lead in weapons miniturazation. (Apologies in advance for forgetting
the names of the interviewees...)
This actually made a lot of sense to me, since the Russians seemed to hold
the contradictory views that Star Wars was infeasable but was still
extremely important to abort; this argument would be sensible in light of
the former.
Question: does anybody know anything about this belief? Is Star Wars a
PR cover for a crash development program in miniturazation of military hardware?
(If nothing else, this "goal" makes explicit some of the ambiguous comments
suggesting "even if Star Wars doesn't succeed fully, we will still benefit
from the spinoffs", with the spinoffs being technology in weapons
miniturization.)
Regards,
David Rogers
(drogers@mit-mc)
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Date: Tue, 12 Nov 85 12:57:14 EST
From: Herb Lin <LIN@MIT-MC.ARPA>
Subject: VMOS instead of krytrons?
Unfortunately semiconductors in general are easily blasted by radiation.
Not just from a nuclear "event" (God, I hate that euphemism!) but also from
cosmic rays (like an ICBM would experience in flight), and from that
warhead
itself. Single event upset from alphas and cosmic rays are the biggest
problem for VMOS. Also neutrons from spontaneous fission displace atoms
in Si
and SiO2 degrading every aspect of performance. VMOS is one of
the "softer"
semiconductor devices around.
The spontaneous fission rate for U-235 is VERY low: A U-235 has a 50%
chance of spontaneous fission in 10**17 years, so spontaneous fission
neutrons aren't an issue, at least not for U-235 warheads. (no
numbers available for Pu-239 -- anyone know where I can get those?)
Alphas can be shielded with ease, I believe, and single event upsets
can be error corrected.
Herb
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Date: Tue, 12 Nov 85 18:27:02 PST
From: Jeffrey S. Gruszynski <jsg@AEROSPACE.ARPA>
Subject: Re: VMOS instead of krytrons
First I want to thank everyone for their comments. As I expected
some of my comments were misunderstood. My comment about SF was wrong, I
not perfect either :-), thanks Herb. I must differ on your comment that
SEU could be prevented simply by shielding. If you know of an easy way of
shielding against 50 MeV iron ions, I'd like to hear about it. (This
is one of the military's standard criterion for SEU hardness.)
I believe I should have separated my discussion of VMOS from
the other subjects more carefully and should elaborated on my examples.
One comment mentioned that Class S RAMs exist from Sandia. Yes, in fact
I am one of the people monitoring the AF contracts for their development.
However, it should be realized that these are specially designed _Static_
RAMs. For the sake of argument I spoke of _Dynamic_ RAMs because of
ubiquity in commercial systems and their _extreme_ "softness". Even with
the existence of the Sandia chips, the memory of choice for "critical"
is still core or plated wire.
I'm sure I'll be getting more mail yet but covers what I've gotten
so far. As I said I appreciate your comments.
jeff
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Date: 1985 November 12 21:44:47 PST (=GMT-8hr)
From: Robert Elton Maas <REM@IMSSS.STANFORD.EDU>
Subject:UN saved us in 1962?
Reply-to: REM%IMSSS@SU-SCORE.ARPA (temporary until nameservers up)
According to the PBS program tonight: WAR, A COMMENTARY "GOODBYE WAR",
the United Nations may have prevented thermonuclear war during the
Cuban missile crisis, by offering a face-saving way for Khrushchev and
also Kennedy to back down without losing face, by pretending to be
accepting the authority of the UN.
I'd like to hear ARMS-Discussion on this claim.
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Date: Wed, 13 Nov 85 14:11:49 est
From: karn%petrus@mouton.ARPA (Phil R. Karn)
Subject: Semiconductors in radiation environments
We (AMSAT, the amateur radio satellite folks) are flying twelve Mostek 4116
16K x 1 NMOS DRAMS on a satellite called Oscar-10 in an elliptical orbit
that carries it through the Van Allen radiation belts (perigee 4,000 km,
apogee 35,000 km) twice per day. These chips provide error-corrected memory
for the onboard computer, a rad-hard 1802 provided by Sandia. The only extra
shielding beyond that of the spacecraft structure is provided by a brass
housing that is bolted around the chips on the PC board. The spacecraft has
been operational for 2.5 years now with an average of only two soft
(correctable) errors per orbit, which invariably occur near perigee.
The radiation environment in this orbit is quite severe, consisting of
protons (primarily at low altitude) and electrons (at high altitude)
with significant flux at energies as high as several hundred MeV.
Given that the radiation environment in the electronics package of a nuclear
warhead (before detonation!) is probably much more benign (highly ionizing
alpha particles which are more easily shielded) I don't see why
semiconductor power switches (which are inherently more resistant to
radiation because of their larger feature sizes) are unsuitable. I suspect
that peak current requirements are more likely the problem.
Congratulations to Herb Lin for his leadoff article in the December 1985
issue of Scientific American.
Phil Karn
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Date: Wed, 13 Nov 85 7:31:21 EST
From: Bruce Nevin <bnevin@bbncch.ARPA>
Subject: proscriptive assumptions
I am missing a couple of issues of Arms-D (3.15 and 3.16). I gather
that I therefore have not seen some relevant postings. I appreciated
the summary and responses from Maas in 3.17. However, I have strong
misgivings about a kind of proscriptive assumption that recurs with
obdurate tenacity in this forum, and comes up in two places in Maas's
posting (emphasis added):
. . . I think it's too much to ask that NOBODY CONTRIBUTE TO
THIS FORUM UNLESS they are a true professional expert.
I never suggested that expertise was or should be a precondition to
submitting postings to this forum. On the contrary, I suggested that we
assume as a default that a contributor (with whom we might be
disagreeing) has some pertinent expertise, rather than assuming that
because we disagree they must be incompetent.
Language that implies disagreement equals incompetence is opinionated
language, and opinionated language is a REAL threat to free and open
discussion. (Hidden pattern: `You're wrong so you're incompetent,
because to be wrong is to make a mistake, and to make a mistake is to be
incompetent, so it's you or me, buddy, and I sure don't want it to be
me.' The process is one of intimidation.)
. . . this discussion of whether it's fair for a private group
to debate such issues WITHOUT INFORMING Sci.Am. IN ADVANCE.
This is one of the things that has amazed me about this discussion. I
never suggested informing SA should be a precondition to discussing
them. I only said that we should let any third party know what we were
saying about them. If they THEN do not contribute their point of view,
it must be because they don't care, rather than because they had no idea
the discussion was going on. Not caring is a valid and possible choice.
However, publishers tend to care what their public think of them.
I've addressed this point several times in this discussion, but it keeps
coming back. I suspect it has hidden roots, like crabgrass. Maybe I've
missed something in the archives. Is there some reason that one's
standing in this forum, either as a contributor or as a topic, is an
especially fragile thing? Is there some reason we feel a need to
challenge the relevance of a topic, or the competence of a contributor,
with special fierceness here?
I observe discussions are more about arms than they are about control.
I have seen little discussion about negotiation as a process that might
be improved in certain ways, for example. A posting about the `I cut,
you choose' proposal that has been getting a lot of attention from
politicians and statement around the world went by with just one
response, something to the effect of `I tried that with my mother when I
was a kid, so it can't work.'
Has anyone anything to say about the Beyond War organization, which aims
to get an electoral majority agreeing that war is obsolete, as a
prerequisite to a REAL search for alternatives? (Be aware that they are
NOT giving away the store, before you flame.)
Those are two topics outside the usual realm of MAD and `deterrence'.
There are others. Is there anyone else here interested in getting
beyond this perpetual game of Ain't it Awful we seem to be playing in
this forum?
Bruce Nevin
bn@bbncch.arpa
BBN Communications
33 Moulton Street
Cambridge, MA 02238
(617) 497-3992
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End of Arms-Discussion Digest
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