Shooting down 'Bandit Satellites'

Ray Dillinger bear at sonic.net
Fri Mar 2 15:29:14 PST 2001


On Thu, 1 Mar 2001, An Metet wrote:

>Suppose can-sats WERE launched illegally, and then started broadcasting 
><time synchronisation signals/OTP/other cypherpunk related> signals, 
>along with a spoken commentary by Radio Free North America (so Joe 
>Sixpack has an excuse when those nice detector van gentlemen knock on 
>his door and ask why he's listening to 128.0 FM) 
>
>Would they be able to physically shoot at it, jam its signal or burn 
>out its electronics from the ground or aircraft altitude? 

Assuming the can-sat were in low earth orbit, yes, they could easily 
shoot it down.  The air force has a few extreme high-altitude craft 
that can launch long-range missiles.  These can actually reach the 
same altitude or nearly, as low-earth-orbit satellites.  

(They cannot reach low earth orbit; that would require them to be 
at that altitude but going much much faster.)

They can't launch a missile fast enough to get low earth orbit, 
either -- but in the final analysis, it doesn't really matter 
whether the satellite hits the missile or the missile hits the 
satellite.  

>Could someone 
>put up enough disposable 'bandit-sats' (expecting to make less orbits 
>than Sputnik) over time to make it uneconomical to keep shooting them 
>out of the sky?

if you're getting one bandit-sat per launch, then the answer is 
plainly no.  Because the missiles or planes don't have to reach 
orbital velocity at all, they are much cheaper to shoot down than 
to put up. 

However, if you get a thousand bandit-sats per launch, and they 
scatter all over the sky once they're up there, it becomes much 
more viable.  It could take weeks or months to shoot them all 
down, and since they wouldn't be clumped together you'd have to 
fly a separate mission for every one of them.  In that scenario 
they are cheaper to launch than to shoot down.  

But still, the launch costs would be a substantial fraction of 
the shootdown costs, and unless you can spend a substantial fraction 
of what the US government would be willing to spend on it, I think 
that's cold comfort at best.

If you go for higher orbits, we might get to see some of the 
stuff the "star wars" research paid for...  At the very least, I'm 
betting on a satellite with a laser which, given a few minutes at 
a hundred-kilometer range, could probably burn through a can-sat.  
Probably something faster than that.  Possibly a bunch of can-sats 
with "intercept and collide" or "get close and explode" missions. 


>Would directional transmissions from ground to 
>satellite be traceable (and would this depend on whether there are 
>other birds in the part of the sky I want to send to)?

depends on how tightly focused.  If you're using radio, you cannot 
focus that tightly, and yes your signal to the satellite can be 
traced.  If you're using laser, it would require them to have a 
satellite with some appropriate directional sensor within a few 
degrees of the satellite.  Hmm, as I think about it, unless your 
laser doesn't illuminate dust in the atmosphere, it might not 
require that much to detect it after all.

>Would retrieval of a returned film capsule be possible before Air 
>Force helicopters descended on the landing site?

Interesting question.  If the film capsule is tiny, nonmetallic, 
and contains no radio equipment, it might be possible for it 
not to show up on radar, in which case it's much less detectable 
than radio etc. 

				Bear





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