From: Henry Spencer <email@example.com>
Subject: Re: Chinese ASAT ( Was: Chinese Satellite to crash to earth!)
Organization: SP Systems, Toronto
Date: Tue, 19 Dec 1995 05:33:27 GMT
In article <thomsonaDJs81o.firstname.lastname@example.org> email@example.com (Allen Thomson) writes:
>>Because the Chinese don't have the capability to shoot our *live*
>>satellites in retaliation.
> ...Any thoughts as to what would be the pacing factor for development
>of a Chinese (or Indian) ASAT for use against satellites in LEO? How
>about GEO? Assuming they decided the need were urgent today, when could
>they start shooting -- in one year, three, ten...?
Months. Weeks if they're clever and in a hurry and don't mind wasting a
few shots. If all you want is a good chance of hitting a LEO satellite
with no more than a few shots, all you need are V-2s with warheads
comprising a small bursting charge and a ton of buckshot. The Peenemunde
rocket team would have been shotgunning for satellites within a week of
being told to. Today's military rocket people aren't set up so well for
fast improvisation, but even so...
GEO is harder, but given that the Chinese have GEO launch capability,
there are things they could do fairly promptly if they didn't mind using
several launches per kill.
If you insist on killing things on the first try, then life gets much
more difficult. But why bother, when shotguns are cheap?
From: Henry Spencer <firstname.lastname@example.org>
Subject: Re: Sat shot down by aircraft - Any truth in it ?
Date: Wed, 4 Sep 1996 19:41:47 GMT
In article <email@example.com> firstname.lastname@example.org (Dwayne Allen Day) writes:
>From an operational standpoint this was a less than desirable weapon.
It did have the huge advantage, however, of being much more mobile than
a lot of the alternatives. This made it much harder for an opponent to
anticipate attack times.
>One of the biggest problems was that it created an awful lot of debris.
>This is not good for all the other satellites flying around up there.
>It's also not good from a public relations standpoint, since simply
>testing it pisses off a lot of scientists and other government agencies...
Testing is actually not a problem -- you test it against something that is
in a sufficiently low orbit that debris lifetimes will be short. That's
what was done, in fact. Operational use against things in somewhat higher
orbits would indeed cause problems.
>The F-15 ASAT was also apparently undesirable due to its high cost. This
>is something I never really understood, though. It supposedly cost a lot
>because there was going to be an entire squadron of F-15 satellite
>killers. But why they couldn't simply a) build carrying kits into all
>new F-15s, or b) develop an easily-installable carrying kit, is unclear
If memory serves, there was a problem in that the stock F-15's performance
was rather marginal for the job, and the engines got special tuning. Pilot
training would also be an issue -- flying near-ballistic trajectories is
not something ordinary fighter pilots train for, and it's not simple (not
if you want to survive it, anyway).
...the truly fundamental discoveries seldom | Henry Spencer
occur where we have decided to look. --B. Forman | email@example.com
Date: 29 Mar 90 17:58:29 GMT
From: firstname.lastname@example.org (Henry Spencer)
Subject: Re: Did SEASAT See More Than It Was Supposed To?
In article <802@geovision.UUCP> pt@geovision.UUCP (Paul Tomblin) writes:
>#... I don't think DoD has any "prerogative" over civilian research
>I seem to recall that a recent test of an SDI or ASAT weapon (sorry I forget
>deatils, just the uproar) was carried out on a perfectly good 'civilian'
>research satellite because DOD's target didn't reach orbit...
This is a vulgar myth. The target was a ***DoD*** research satellite with
some instruments that were being used by civilian scientists. It was DoD
property, theirs to destroy if they felt like it. Some scientists were
upset about the loss of a satellite that was still returning good data, but
their case was considerably weakened by the fact that nobody had done much
work on analyzing that data for several years -- it was piling up unread.
Apollo @ 8yrs: one small step.| Henry Spencer at U of Toronto Zoology
Space station @ 8yrs: .| uunet!attcan!utzoo!henry email@example.com
From: Henry Spencer <firstname.lastname@example.org>
Subject: Re: Attacking ISS (was Re: debris vs ISS (was Re: chicken cannon))
Date: Mon, 6 Apr 1998 00:49:57 GMT
In article <email@example.com>,
Dwayne Allen Day <firstname.lastname@example.org> wrote:
>: > I'm not sure that a SCUD can get to orbit.
>: It can't, but it doesn't have to. Just tossing stuff up into the path of
>: a satellite is quite effective enough, as witness the tests of the F-15
>: ASAT system some years back.
>...which did not work like this at all. It did not just get "tossed up"
>to the right altitude--it homed in on the heat signature...
Well, that wasn't quite what was being discussed -- the point was that you
don't need to go into orbit for this purpose. And the ASAT kill vehicle
actually *did* just get tossed up, *after which* it homed in on the target.
>... (no mean feat
>when you consider that the satellite wasn't really generating heat).
Most any satellite generates heat, actually, in the sense of absorbing
sunlight and re-emitting most of the energy as thermal infrared. The
emission is admittedly fairly weak, although seeing it against a black sky
background helps greatly.
>...Anyone who thinks that simply "throwing a
>bucket of ball bearings" into the path of the station is easy has not
>bothered to think about how they will disperse once in orbit or how good
>your guidance needs to be. More than a few hundred feet away and the
>shrapnel would be so dispersed that you'd be lucky to hit something even
>as big as the station.
Well, let's do a few numbers. Assume we have a 500kg payload of the
proverbial half-inch ball bearings. They mass about 8g each, so our
payload is about 60,000 of them (knocking a bit off for bursting charge
etc.). They disperse in some sort of cloud. Dispersal along the relative
velocity vector is largely irrelevant, because that affects only the
timing of an impact; what we care about is dispersal in a plane at right
angles to that vector. A 1km-dia circle in that plane has an area of
about 0.8km^2, and assuming uniform dispersal (a generous assumption), it
has a ball bearing in every 13m^2.
I don't remember the current average frontal area of the station, but a
single module that fills a shuttle cargo bay (and the major modules come
pretty close to that) will have a frontal area of about 80m^2 sideways and
about 15m^2 end-on. So if the station passes through that 1km circle, any
module that is broadside-on is essentially certain to be hit by at least
one ball bearing and probably several. Some of the modules that are
end-on will be sheltered behind others; of those that aren't, perhaps half
will be hit. So a miss of several hundred meters -- not feet -- is not
merely a hit but a thoroughly devastating one.
Now granted, in real life the dispersal won't be uniform. On the other
hand, thinning the cloud of ball bearings by a factor of several clearly
still leaves a major hazard to the station, with damage to solar arrays
and radiators nearly certain and at least one puncture quite likely. And
we can thicken the cloud by a factor of two just by going to 1cm bearings,
which are probably still good enough for near-assured punctures, given
that they're still about three times the mass of the nominal 1cm piece of
aluminum space debris.
As a rough rule of thumb, a missile which can put a 500kg payload within,
say, 1km of the station at least once every few tries presents a very
serious threat. I don't happen to know how accurate Scuds are... but this
does not sound like it's definitely impossible.
Being the last man on the Moon | Henry Spencer
is a very dubious honor. -- Gene Cernan | email@example.com
From: firstname.lastname@example.org (George Herbert)
Subject: Re: Third Country ASAT
Date: 9 Apr 1999 23:44:08 -0700
Hunt Johnsen Designs <email@example.com> wrote:
>How about steel shot or iron filings? [...]
The right answer usually turns out to be 4-6mm ball bearings
(not airgun style "BBs"). What you are looking for is a
relatively cheap projectile with high one-impact lethality,
as a dozen sand grain type hits may well not hurt the target
all that much.
That lethality requires a certain KE content, and also
requires a fairly strong projectile... random steel is ok,
but the stronger the better, it gives you better secondary
projectiles and fragments off the primary projectile when
it vaporizes hitting the target's body.
-george william herbert