Future Space War

Dirk Bruere at Neopax writes:

Gordon D. Pusch wrote:
"Paul F Austin" writes:
"Greg" wrote
"Dirk Bruere at Neopax" wrote

A megaton nuke exploded in space will wipe out every bit of unshielded
electronics for around 800 miles around the ground zero.
That means computers, car ignition systems, telephones, radios, TVs etc
It would wipe out a modern nation's economy overnight.

Many backup generator systems are unlikly to be affected. Wipe a
modern nations economy--i doubt it. Unless the economy was already in
big decline and fall. Life would go on.

Note that many space based sats will *not* be affected ie
geo-stationary sats

Actually, the prompt dose from a megaton exoatmospheric detonation would
kill every non-military geo-sat in line of sight. With no atmospheric
shielding, the dose rate would cause catastrophic damage to many systems at
that distance.

I think you are forgetting about a little thing called "The Inverse Square Law"...

We could try some figures.
1Mt detonation with (say) 25% of its energy as X and Gamma radiation.

IMO that is a gross over-estimate of the X-ray and gamma yield (a 5% yield
in "radiation" is more typical, http://www.fas.org/nuke/intro/nuke/radiation.htm,
where the term "radiation" includes both neutrons _AND_ gammas), but I'll grant it
for the sake of argument...


That's around 10^15 Joules
The surface area of a 2000km dia sphere is 4 * pi * 10^12 m^2 = approx 10^13 sq m

So at 1000km we have a radiation dose of 100J per sq m, which is probably close
to fatal for electronics.

So at a guess, 1000km is around the nearest 'safe' distance.

...And since the sphere represented by LEO is over an order of magnitude
larger in diameter than 1000 km, and GEO is 2.5 orders of magnitude larger
than 1000 km, even before correcting for your gross overestimate of the
radiation yield, it is highly likely that the overwhelming majority of
LEO sats will survive a single 1 Mt exoatmospheric blast, and probably
_ALL_ of the GEO sats will survive.

To further drive home this argument, suppose I assume your radiation yield
and "kill thresholds" are reasonable: It will take on the order of 180
nicely-spaced 1 Mt bombs to wipe out all LEO assets (rough estimate of the
number of 2000 km diameter patches required to tile LEO), and on the order
of 130 nicely-spaced 1 Mt bombs to wipe out all GEO assets (rough number
of 2000 km arc segments around GEO). That means a single 1 Mt bomb will
only take out around a _HALF OF A PERCENT_ of either LEO assets or GEO
assets --- and it can't take out both of them simultaneously!


-- Gordon D. Pusch

perl -e '$_ = \n"; s/NO\.//; s/SPAM\.//; print;'

(Nick Maclaren) wrote

And submarines had better not get located - I would bet that those
things make very good depth charges!

http://www.smdc.army.mil/KWAJ/KMRSANDR.HTM

Jordan179 wrote:

Dirk Bruere at Neopax wrote in message ...

Gordon D. Pusch wrote:


I think you are forgetting about a little thing called "The Inverse Square Law"...

We could try some figures.
1Mt detonation with (say) 25% of its energy as X and Gamma radiation.
That's around 10^15 Joules
The surface area of a 2000km dia sphere is 4 * pi * 10^12 m^2 = approx 10^13 sq m

So at 1000km we have a radiation dose of 100J per sq m, which is probably close
to fatal for electronics.

So at a guess, 1000km is around the nearest 'safe' distance.


Now I think you're forgetting about a little thing called "the Earth's
atmosphere." While your math would probably work out in a vacuum, in

That was a calc for ionising radiation kill in space.

order to fry electronics at the surface, the EMP has to get through
the atmosphere in the first place, and the atmosphere contains layers
of charged particles which could interfere with the pulse.

It is the atmosphere which generates the EMP, and the EMP is most intense at the
surface.

Btw, considering that the danger of EMP's was first noticed in the
1960's, it's criminally stupid if we have STILL not hardened vital
electronics nodes against them.

It is impractical to do it for more than very essential military equipment.
Continuing miniaturisation just makes the problem worse.
--
Dirk

The Consensus:-
The political party for the new millenium
http://www.theconsensus.org

Gordon D. Pusch wrote:

Dirk Bruere at Neopax writes:


Gordon D. Pusch wrote:

"Paul F Austin" writes:

"Greg" wrote

"Dirk Bruere at Neopax" wrote


A megaton nuke exploded in space will wipe out every bit of unshielded
electronics for around 800 miles around the ground zero.
That means computers, car ignition systems, telephones, radios, TVs etc
It would wipe out a modern nation's economy overnight.

Many backup generator systems are unlikly to be affected. Wipe a
modern nations economy--i doubt it. Unless the economy was already in
big decline and fall. Life would go on.

Note that many space based sats will *not* be affected ie
geo-stationary sats

Actually, the prompt dose from a megaton exoatmospheric detonation would
kill every non-military geo-sat in line of sight. With no atmospheric
shielding, the dose rate would cause catastrophic damage to many systems at
that distance.


I think you are forgetting about a little thing called "The Inverse Square Law"...

We could try some figures.
1Mt detonation with (say) 25% of its energy as X and Gamma radiation.


IMO that is a gross over-estimate of the X-ray and gamma yield (a 5% yield
in "radiation" is more typical, http://www.fas.org/nuke/intro/nuke/radiation.htm,
where the term "radiation" includes both neutrons _AND_ gammas), but I'll grant it
for the sake of argument...



That's around 10^15 Joules
The surface area of a 2000km dia sphere is 4 * pi * 10^12 m^2 = approx 10^13 sq m

So at 1000km we have a radiation dose of 100J per sq m, which is probably close
to fatal for electronics.

So at a guess, 1000km is around the nearest 'safe' distance.


..And since the sphere represented by LEO is over an order of magnitude
larger in diameter than 1000 km, and GEO is 2.5 orders of magnitude larger
than 1000 km, even before correcting for your gross overestimate of the
radiation yield, it is highly likely that the overwhelming majority of
LEO sats will survive a single 1 Mt exoatmospheric blast, and probably
_ALL_ of the GEO sats will survive.

Actually LEOs may fare rather worse than that, depending on a number of factors.
There could be considerable damage caused by charged particles spiraling in the
Earth's mag field across far greater distances.

To further drive home this argument, suppose I assume your radiation yield
and "kill thresholds" are reasonable: It will take on the order of 180

Within order of magnitude anyway.

nicely-spaced 1 Mt bombs to wipe out all LEO assets (rough estimate of the
number of 2000 km diameter patches required to tile LEO), and on the order
of 130 nicely-spaced 1 Mt bombs to wipe out all GEO assets (rough number
of 2000 km arc segments around GEO). That means a single 1 Mt bomb will
only take out around a _HALF OF A PERCENT_ of either LEO assets or GEO
assets --- and it can't take out both of them simultaneously!

Like I said, you are neglecting charge trapping.
I seem to recall that one exo atmospheric nuclear test unexpectedly knocked out
a satellite due to this mechanism.

--
Dirk

The Consensus:-
The political party for the new millenium
http://www.theconsensus.org

Ian Stirling wrote in message ...
In sci.space.tech Jordan179 wrote:
Dirk Bruere at Neopax wrote in message ...
Gordon D. Pusch wrote:

I think you are forgetting about a little thing called "The Inverse Square Law"...

We could try some figures.
1Mt detonation with (say) 25% of its energy as X and Gamma radiation.
snip
Now I think you're forgetting about a little thing called "the Earth's
atmosphere." While your math would probably work out in a vacuum, in
order to fry electronics at the surface, the EMP has to get through
the atmosphere in the first place, and the atmosphere contains layers
of charged particles which could interfere with the pulse.

Read back, and you'll find that the statement was that a megaton
exoatmospheric detonation will kill all unhardened satellites in line
of sight.

Oh, ok.

However, I don't think that this statement is accurate either, since
some satellites might be "in line of sight" but too far from the
detonation for sufficient energy to reach them to destroy their
electronics.

Also, given the Sun's nasty habit of flaring randomly, I think that
it's pretty dumb not to harden the electronics on satellites.

Sincerely Yours,
Jordan

"Paul F Austin" wrote in message
...

[snip]

I participated in a panel discussion on hardening satellite communications
at the FCC about two years ago. The upshot is that hardening the satellite
control links against jamming and spoofing is more urgent (because it can
be
attacked more cheaply) and that satellite owners will not harden sats
against these kinds of threats unless required to do so by licensing
agencies.

Very little civilian infrastructure is built to survive nuclear war.

(A certain British nuclear submarine was called HMS Revenge
not HMS Police Action. We want you to deter nuclear war
rather than fight one.)

Spoofing can be prevented by encrypting the control
channel. AES encryption, which is as strong as most
military systems, can be performed using a single
off the shelf chip. It can also be performed using
software. Only decrypted commands with the correct
time and date should be obeyed.
http://www.jennic.com/site/ip_produc.../j-aes-cop.pdf

Commercial firms will protect their equipment against
attack when they consider it worth while. Time on
satellites costs many dollars per hour. A blackmailer
only needs to switch a satellite off for a short time
before it becomes cheaper to build encryption in.

Multi-million dollar solar powered communications
satellites can be rendered useless by instructing
the satellite to point its solar cells away from the
sun and simply waiting for the batteries to go flat.

A ground station used to jam the control channel
of a satellite does not need to be in the front line,
it can be in a military base a hundred miles behind
the line.

Since communication satellites have not been attacked
by the military, terrorists or blackmailers neither they
nor their insurance companies think it is worthwhile.

Andrew Swallow

"Paul F Austin" writes:

As I said in another answer, a 1MT exo detonation detonated just above the
atmosphere would deposit about 3MRad at GEO. That's gamma. The sun's
emissions are dominated by electrons with a minority of protons. Electrons
are relatively easy to shield against (high energy protons are not). As a
result, flares and all, a GEO sat is designed to withstand about 35-50KRAD
over life. A design margin of 2 or 3 is added getting you close to
100-150KR.


OK, math time. Your 100-150 kRad figure corresponds with my own experience
designing flight hardware. But, one megaton in LEO giving 3 MRad in GEO?
Not buying it.

One megaton is 4.2E15 Joules. LEO to GEO is about 3.5E7 meters, depending
on how we define "LEO". One Rad is 0.01 Joules per kilogram of deposited
energy. And typical shielding density for unhardened spacecraft electronics
is still on the order of 100 mils of aluminum, mass density of 6.85 kilograms
per square meter.

One megaton in LEO produces an integrated flux of 4.2E15/(4*pi*3.5E7^2)
or 0.27 J/m^2 at GEO.

If every erg released by the detonation is gamma radiation, with a spectrum
optimized for energy deposition just inside 100 mils of shielding, that gives
us 0.27 / (e * 6.85) = 0.0125 joules per kilogram at the target electronics.

A little over *one* Rad, not three million.


I do not see how prompt gamma or X-ray radiation from a nuclear detonation
can be anything more than a very local hazard to satellites. The 100-kRad
level will be reached only at distances of a hundred kilometers or so.

A high-altitude nuclear detonation can be a global hazard to satellites in
*Low* Earth Oribit, but that's from the high-energy electrons, in part due
to magnetospheric trapping (a short-lived but intense Van Allen belt) and
in part due to atmospheric interaction producing an electromagnetic pulse.
The former isn't even limited to line-of-sight; one well-placed large nuke
can take out every unhardened *LEO* bird.

But the very same magnetospheric trapping protect the GEO birds from that
effect. And the numbers just don't add up for prompt X-ray/gamma.


--
*John Schilling * "Anything worth doing, *
*Member:AIAA,NRA,ACLU,SAS,LP * is worth doing for money" *
*Chief Scientist & General Partner * -13th Rule of Acquisition *
*White Elephant Research, LLC * "There is no substitute *
* for success" *
*661-718-0955 or 661-275-6795 * -58th Rule of Acquisition *

"Paul F Austin" wrote in message
From Messenger (1986), figure 4.23, the prompt gamma dose of a 1MT,
exoatmospheric detonation at 200Km is 10^11 Rad(Si). Good ole inverse square
law cuts that by a factor of 32000 or...3.1MRAD(Si).

I'm in the business. Including design margins, commercial GEO sats design to
between 50KRAD and 100KRAD at the piecepart level. There is some shielding
from spacecraft structure but not very much.

Every non-military satellite in line of sight of a 1MT detonation is dead as
8 inch floppies.

The units don't seem right. Rad = radiation absorbed dose . This is
not an intesity. ie radation per unit area.

please clarify

Greg

"John Schilling" wrote in message
...
"Paul F Austin" writes:

As I said in another answer, a 1MT exo detonation detonated just above
the
atmosphere would deposit about 3MRad at GEO. That's gamma. The sun's
emissions are dominated by electrons with a minority of protons.
Electrons
are relatively easy to shield against (high energy protons are not). As a
result, flares and all, a GEO sat is designed to withstand about
35-50KRAD
over life. A design margin of 2 or 3 is added getting you close to
100-150KR.


OK, math time. Your 100-150 kRad figure corresponds with my own
experience
designing flight hardware. But, one megaton in LEO giving 3 MRad in GEO?
Not buying it.

One megaton is 4.2E15 Joules. LEO to GEO is about 3.5E7 meters, depending
on how we define "LEO". One Rad is 0.01 Joules per kilogram of deposited
energy. And typical shielding density for unhardened spacecraft
electronics
is still on the order of 100 mils of aluminum, mass density of 6.85
kilograms
per square meter.

One megaton in LEO produces an integrated flux of 4.2E15/(4*pi*3.5E7^2)
or 0.27 J/m^2 at GEO.

If every erg released by the detonation is gamma radiation, with a
spectrum
optimized for energy deposition just inside 100 mils of shielding, that
gives
us 0.27 / (e * 6.85) = 0.0125 joules per kilogram at the target
electronics.

A little over *one* Rad, not three million.


I do not see how prompt gamma or X-ray radiation from a nuclear detonation
can be anything more than a very local hazard to satellites. The 100-kRad
level will be reached only at distances of a hundred kilometers or so.

A high-altitude nuclear detonation can be a global hazard to satellites in
*Low* Earth Oribit, but that's from the high-energy electrons, in part due
to magnetospheric trapping (a short-lived but intense Van Allen belt) and
in part due to atmospheric interaction producing an electromagnetic pulse.
The former isn't even limited to line-of-sight; one well-placed large nuke
can take out every unhardened *LEO* bird.

But the very same magnetospheric trapping protect the GEO birds from that
effect. And the numbers just don't add up for prompt X-ray/gamma.

John, the Moderator apparently killed my other post. Here's the source:

George Messenger's "The Effects of Radiation on Electronic Systems", 1986.
figure 4.23. Now for the mea culpa. I misread the figure and you are
correct. The prompt dose for a 1MT exo detonation at 200Km is 10 Rad(Si),
not 10^11. Never Mind.

Andrew Swallow wrote:


Since communication satellites have not been attacked
by the military, terrorists or blackmailers neither they
nor their insurance companies think it is worthwhile.

Yet.

--
Dirk

The Consensus:-
The political party for the new millenium
http://www.theconsensus.org