Date: Mon, 26 Sep 88 01:08:36 PDT
From: Ted Anderson <ota@angband.s1.gov>
Message-Id: <8809260808.AA10960@angband.s1.gov>
To: Space+@andrew.cmu.edu
Reply-To: Space+@andrew.cmu.edu
Subject: SPACE Digest V8 #376

SPACE Digest                                      Volume 8 : Issue 376

Today's Topics:
		     Re: Transmutation of Metals
			     Re: Phoenix
			   Re: Time Travel
	     Re: The sun as a trashcan (was : Plutonium)
			  Re: Why no aliens
			       Re: SDI
   Re: Unmanned w/old SRBs (was Re: space news from July 11 AW&ST)
		    Re: Shuttle names--old and new
			       Re: SETI
			       Re: SDI
	    Re: "It's because of all those satellites..."
		   Self-replicating/mutating robots
----------------------------------------------------------------------

Resent-Message-Id: <0X9xYry00Vse07D4FD@andrew.cmu.edu>
Resent-Date: Fri,  9 Sep 88 09:14:31 -0400 (EDT)
Resent-From: Ted Anderson <ota+@andrew.cmu.edu>
Resent-To: Space <space+@andrew.cmu.edu>
Return-Path: <SAC.DYESGPF@e.isi.edu>
Date: 8 Sep 1988 18:40-CDT
Sender: SAC.DYESGPF@e.isi.edu
Subject: Re: Transmutation of Metals
From: SAC.DYESGPF@e.isi.edu
To: ota@angband.s1.gov

> I once read that the Atomic Energy Commission built a huge
> machine to make Pu out of U by bombarding it with protons,
> using simple electrostatic acceleration.  I no doubt have
> the above all wrong, but the thing was run for several years.

I am not sure if this is what you are referring to, but Pu 238
was first created by bombarding U 238 with deuteron in a 60 inch
cyclotron at Berkeley in 1940.  The research team involved was
Glenn T. Seaborg, Edwin M. Mcmillan, Joseph W. Kennedy, and
Arthur C. Wahl.

The isotope Pu 239 (which is in greater demand) is made with
U 238 (plentiful and very stable - nonfissile) and U 235 (much
less abundant and fissile) in a breeder reactor.

Although energy is required to run a cyclotron, the breeder
reactor generates a great deal of heat which can be used to
generate power.  Of course, Pu 238 produces a fair amount of
heat because of the high rate of alpha decay (half life of 86
years).  Put a chunk of this inside a thermocouple pile and you
have a device which can be used for powering electronics in
remote areas such as deep space.


Al Holecek
<SAC.DYESGPF@E.ISI.EDU>

------------------------------

Date: 7 Sep 88 19:03:00 GMT
From: mcvax!ukc!dcl-cs!nott-cs!pyr1.cs.ucl.ac.uk!william@uunet.uu.net
Subject: Re: Phoenix


>Hudson has this to say about reusable vehicles:
> ....
>"It is no argument to say that launch vehicles are more complex
>devices than, for example, an F-15 or 767.  Clearly they are not. 
> ..."

Is this true?  It doesn't appear clear to me, I'm afraid!  There was
a major discussion a little while back that seemed to conclude that
rocket nozzle technology is a trial-and-error black art.  How much of
the rest of the job is so unpredictable?  And what parts of aircraft
are similarly designed purely on an "it worked last time" basis?

			... Bill

************************************************************************
Bill Witts, CS Dept.     *    Nel Mezzo del cammin di nostra vita
UCL, London, Errrp       *    mi ritrovai per una selva oscura
william@cs.ucl.ac.uk     *    che la diritta via era smarrita.
************************************************************************

------------------------------

Date: Fri, 9 Sep 1988 11:58-EDT 
From: Dale.Amon@h.gp.cs.cmu.edu
Subject: Re: Time Travel

I believe Dave Flory is incorrect.

One must examine the path of a vehicle on a Space-Time diagram. As you
approach the speed of light, your path in space time becomes more and
more a 'time-like' path instead of a 'space-like' path.

The often mentioned time travel in the vicinity of a massive rotating
cylinder is caused by the effect of space-like paths being pulled
around the cylinder until they become time-like paths. Thus following
one of the causes travel in time.

Presumably, if one went faster than light in normal space by tunneling
through the forbidden value of c, then one would be traveling very
time-like paths.

------------------------------

Date: 7 Sep 88 21:14:08 GMT
From: linus!philabs!micomvax!ncc!alberta!mnetor!utzoo!henry@husc6.harvard.edu  (Henry Spencer)
Subject: Re: The sun as a trashcan (was : Plutonium)

In article <2830@pt.cs.cmu.edu> jgk@speech2.cs.cmu.edu (Joe Keane) writes:
>Someone will curse the fools who sprayed plutonium on her land.

Only if some bright government forces the Lunar Plutonium Disposal Company
to sell the contaminated land.  (This is what happened at Love Canal.)
Remember, I assumed reasonable accuracy in aiming.  Nobody in his right
mind will try to homestead a waste dump.
-- 
Intel CPUs are not defective,  |     Henry Spencer at U of Toronto Zoology
they just act that way.        | uunet!attcan!utzoo!henry henry@zoo.toronto.edu

------------------------------

Date: 7 Sep 88 21:42:02 GMT
From: linus!philabs!micomvax!ncc!alberta!mnetor!utzoo!henry@husc6.harvard.edu  (Henry Spencer)
Subject: Re: Why no aliens

In article <1950@brahma.cs.hw.ac.uk> adrian@cs.hw.ac.uk (Adrian Hurt) writes:
>Take some sort of propulsion and control/guidance system. And enough fuel to
>drive it for, say, a month continuously...
>Could this be done?

Compute how much fuel it would take to accelerate an asteroid at one gee
for a month.  Not practical at present.
-- 
Intel CPUs are not defective,  |     Henry Spencer at U of Toronto Zoology
they just act that way.        | uunet!attcan!utzoo!henry henry@zoo.toronto.edu

------------------------------

Date: 7 Sep 88 21:18:49 GMT
From: linus!philabs!micomvax!ncc!alberta!mnetor!utzoo!henry@husc6.harvard.edu  (Henry Spencer)
Subject: Re: SDI

In article <1774@hoqax.UUCP> lmg@hoqax.UUCP (45323-LARRY GEARY) writes:
>You don't need an SDI to control access to orbit. The Iranians could deny
>the U.S. access to space by placing one of their speedboats with sailors
>with shoulder launched missiles off Cocoa Beach. In fact, anyone else with
>the desire to do this could probably pull it off, even an individual. Isn't
>the Ariane launch site near the ocean? How about Vandenberg AF base? Only
>the Soviets have a reasonably secure, inland launch site.

All the Western launch sites are coastal sites, for range-safety reasons.
The Soviets didn't have the choice.

However, any Iranian speedboats showing up off Cocoa Beach would be in
deep trouble very quickly.  Start with AC-130 gunships (which are present
at the Cape and Vandenberg for all launches) and work up from there.
The issue of launch-site security is not being ignored just because some
of the surroundings happen to be water.
-- 
Intel CPUs are not defective,  |     Henry Spencer at U of Toronto Zoology
they just act that way.        | uunet!attcan!utzoo!henry henry@zoo.toronto.edu

------------------------------

Date: 7 Sep 88 21:27:36 GMT
From: linus!philabs!micomvax!ncc!alberta!mnetor!utzoo!henry@husc6.harvard.edu  (Henry Spencer)
Subject: Re: Unmanned w/old SRBs (was Re: space news from July 11 AW&ST)

In article <6185@dasys1.UUCP> tneff@dasys1.UUCP (Tom Neff) writes:
>>... The NRC report on
>>shuttle frequency put it even more strongly:  if the shuttle continues
>>flying, another orbiter *WILL* be lost eventually.
>
>Yes, but the NRC doesn't really have any better basis for making a
>statement like that, than NASA does for implying we won't lose one.

Sorry, wrong.  NRC justified its predictions in detail.  Remember Murphy:
betting that things will fail is a whole lot safer than betting that
everything will work perfectly.  Check out the safety record of segmented
solid boosters.  Then look at the crash rate for advanced military aircraft.
Remember that losing an orbiter does not require another Challenger
disaster; possibly the most likely way to lose an orbiter is a landing
accident, which might well leave crew and payload intact but damage the
orbiter badly enough to make it unflyable.  This happens all the time to
aircraft.  There have been one or two narrow escapes in the shuttle
program already, in fact, due to the orbiter's somewhat marginal landing
gear.

>Sure, if we used the fleet for 30+ years and expanded it to 10
>orbiters, losses would be inevitable.  They would also be easier to
>take.  What we cannot afford to do is ace one of the remaining three
>right now...

Then, as I said, we must send them to the Smithsonian at once.  No matter
how careful you are, you cannot fly them without taking risks.  If we keep
on flying them, even just our present little fleet, losses are inevitable.
-- 
Intel CPUs are not defective,  |     Henry Spencer at U of Toronto Zoology
they just act that way.        | uunet!attcan!utzoo!henry henry@zoo.toronto.edu

------------------------------

Date: 7 Sep 88 21:46:26 GMT
From: linus!philabs!micomvax!ncc!alberta!mnetor!utzoo!henry@husc6.harvard.edu  (Henry Spencer)
Subject: Re: Shuttle names--old and new

In article <880906083854.146@VLSI.JPL.NASA.GOV> hairston%23666%utadnx%utspan.span@VLSI.JPL.NASA.GOV writes:
> ..."Columbia" was the name of Jules 
>Verne's spaceship in "From the Earth to the Moon", which was why it was
>also chosen for the command module of Apollo 11...

No.  Verne's projectile was unnamed, as I recall, and the cannon was the
Columbiad (note final D).  The near-miss on Verne was noted for Apollo 11,
but it was a secondary issue.

>... Supposedly either "Challenger"
>or "Atlantis" was the name of Tom Swift's rocket, but I've never been
>able to track that down for sure...

The original Tom Swift I don't know about, but then I'm not sure he had
a rocket ship.  Tom Swift Jr's 1950s rocket ship was the Star Spear, if
I'm not mistaken (it's been a long time since I read TSJ#3...).
-- 
Intel CPUs are not defective,  |     Henry Spencer at U of Toronto Zoology
they just act that way.        | uunet!attcan!utzoo!henry henry@zoo.toronto.edu

------------------------------

Date: 7 Sep 88 22:01:33 GMT
From: linus!philabs!micomvax!ncc!alberta!mnetor!utzoo!henry@husc6.harvard.edu  (Henry Spencer)
Subject: Re: SETI

In article <1034@bucket.UUCP> leonard@bucket.UUCP (Leonard Erickson) writes:
>Henry, any guesses as to how big a probe we could send to say, Alpha Centauri,
>if we didn't care about the cost (in the same sense that the Soviets don't
>care about their defense spending). By we, I mean the goverments of Earth.
>
>Say an Oriion powered probe using the existsing nuclear arsenals?

If we were to tackle this seriously, what we probably want to do is to
dust off the proposal that Robert Forward et al ("et al" being a number
of people from places like JPL and Los Alamos, as I recall) made to SDIO:
get antimatter propulsion going.  First phase does the detail engineering
of handling and such.  Second phase builds a specialized accelerator that
makes enough antimatter in a year to test-fire an engine.  Third phase
builds a complex about the size of the Hanford works that makes enough
antimatter to give us the solar system.  I think it was five years per
phase, with no breakthroughs needed.  Probably faster if you hurry.
Another Hanford-sized works should suffice, I'd guess, to get a few tons
up to a few percent of the speed of light every year or two.

Incidentally, SDIO thought the idea would probably work but decided that
it was a bit too long-term to suit them.
-- 
Intel CPUs are not defective,  |     Henry Spencer at U of Toronto Zoology
they just act that way.        | uunet!attcan!utzoo!henry henry@zoo.toronto.edu

------------------------------

Date: 7 Sep 88 21:39:55 GMT
From: linus!philabs!micomvax!ncc!alberta!mnetor!utzoo!henry@husc6.harvard.edu  (Henry Spencer)
Subject: Re: SDI

In article <7757@cit-vax.Caltech.Edu> lim@cit-vax.UUCP (Kian-Tat Lim) writes:
>Something that has been bugging me throughout this "denying access to space
>via Stinger" discussion.  How much is the warhead of a shoulder-fired weapon
>going to disturb an SSME/Ariane/whatever, considering that the hottest target
>is the exhaust plume?  With all that energy spewing out, it would seem to me
>that the extra "bump" from a 50-pound explosive (to be generous) would be
>negligible.

Don't overlook the possibility of trouble caused by disturbances in the
exhaust plume; 50 pounds of explosive is one nasty big explosion.  The
shoulder-launched weapons don't pack that much explosive, but it's still
nothing you want to be standing near when it goes off.  Then too, newer
warheads are not pure blast weapons, since that is a fairly inefficient
way to do things.  They are fragmentation designs that will throw solid
lumps at high velocities quite a distance.

Do not assume that heat-seeking weapons will home on the exhaust plume.
The brightest targets are the nozzles, actually.  The plume is hotter
but doesn't radiate nearly as efficiently.  (At least, this is the case
for aircraft; I think it will read over to rockets.)  The older infrared
missiles homed on the jet exhaust nozzles.  The newer ones are sensitive
enough to home on a jet plume, since the nozzles can't be seen from the
front, but I think they'll still go for the nozzles if/when they come in
sight.

Finally, nowadays it's common for the missile to have a bias built into
it so that it tries to hit slightly *ahead* of the big bright spot.
-- 
Intel CPUs are not defective,  |     Henry Spencer at U of Toronto Zoology
they just act that way.        | uunet!attcan!utzoo!henry henry@zoo.toronto.edu

------------------------------

Date: 9 Sep 88 05:36:29 GMT
From: att!ihnp4!poseidon!psrc@ucbvax.berkeley.edu  (Paul S. R. Chisholm)
Subject: Re: "It's because of all those satellites..."

< "*NO* toon can resist the old shave-and-a-haircut bit!" >

In article <7844@cit-vax.Caltech.Edu>, mangler@cit-vax.Caltech.Edu (Don Speck) writes:
> This last weekend my Mom mentioned to me that the weather where
> she lives is unusual this summer (it is here too), and she posited
> that global weather is messed up "because of all those satellites".
>Don Speck   speck@vlsi.caltech.edu  {amdahl,ames}!cit-vax!speck

I remember a bus driver telling me, in all seriousness, that the weather
had gone to pot because of "all the junk they left up there on the
Moon".

Paul S. R. Chisholm, psrc@poseidon.att.com (formerly psc@lznv.att.com)
AT&T Bell Laboratories, att!poseidon!psrc, AT&T Mail !psrchisholm
I'm not speaking for the company, I'm just speaking my mind.

------------------------------

Date: Fri, 9 Sep 88 17:49:08 EDT
From: John Roberts <roberts@cmr.icst.nbs.gov>
Subject: Self-replicating/mutating robots


>From: oliveb!tymix!antares!pnelson@ames.arc.nasa.gov  (phil nelson)
>Subject: Re: SETI: Why don't we hear anything?

> I think that the problem of creating these "self-replicating robots" may
>be more difficult than we imagine, perhaps too difficult even for our
>hypothetical "advanced" xenophobes.
See Henry Spencer's comments on the difficulty of predicting future advances in
technology. Much of the difficulty of making self-replicating robots lies in
the definition of "self-replicating". A moving, working robot that can generate
a working copy of itself from raw materials would be very difficult to create.
A robot that can assemble a large factory which produces robots and factory
parts would probably be much simpler. James Hogan describes such a system in
"The Code of the Life-maker". In the story, a large spaceship would scout
out an uninhabited world, then a team of robots would set up factories which
would produce more robots, more factories, spaceships, and manufactured goods
to return to the parent civilization. This may be a more likely scenario than
the Berserkers. We may eventually get around to exploring planets of other
star systems, only to find them covered with robots and "keep out" signs.

> Among other lifelike qualities this race of robots might require is the
>ability to adapt to new conditions. Assuming for a moment that these robots
>can be (and are) created, isn't it likely that they would either evolve into
>something more benevolent or (perhaps more likely) devolve into something
>much less terrible?
It depends mostly on how they were designed, which in turn depends on the
motives, skills, and experience of the designers. In the Berserker stories
and the Star Trek episode with the giant ice cream cone, the robots had
been designed to attack a specific enemy, but had then generalized the
instructions to cover all life/planets. In Hogan's novel, the factory
instructions were scrambled by a burst of radiation, causing the system
to mutate. Any reasonable effort to put error detection/correction
capability into the design should make such events *extremely* unlikely.

In any event, I think the sensible thing to do is to listen for a while
before trying to transmit anything.

                              John Roberts
                              roberts@cmr.icst.nbs.gov

------------------------------

End of SPACE Digest V8 #376
*******************