Space Terrorism

Space terrorism? Yes, space terrorism. This article, by someone at the European Space Policy Institute, hypes a terrorist threat I've never seen hyped before. The author waves a bunch of scare stories around, and then concludes that "the threat of 'Space Terrorism' is both real and latent," then talks about countermeasures. Certainly securing our satellites is a good idea, but this is just silly.

Posted on June 29, 2010 at 11:42 AM • 57 Comments


ScottJune 29, 2010 11:53 AM

This is a stunning example of retreading old thinking for new budgets. The author clearly has no concept of the distinction between "terrorism" and "warfare".

RayJune 29, 2010 11:57 AM

Recent wannabe terrorists could not even properly blow up their own shoes or underwear, and this person is asserting that they pose a danger to tiny objects orbiting the planet many miles from the surface? Riiiiiight... Nothing to see here, folks, move along.

Clive RobinsonJune 29, 2010 12:16 PM


The biggest threat to satellites is solar radiation, which is also one of the biggest threats to above ground power and communication grids.

The next bigest threat to "spaceship earth" is lumps of rock droping in at very very high velocity.

Now if you went up to an appropriate part of the solar system you would find plenty of rocks from the size of pebbles to things the size of small islands.

We have not had any real rocks drop on populated areas in living memory. And we have to count ourselves lucky for that. For some reason that is not understood the rocks seem to prefere hitting the moon...

Now in theory there is absolutly nothing to stop people putting "self repicating robot probes" up into sapce to make rocks into guided weapons.

In practice however...

Me I'd be slightly worried that within the next 20 years some nation or organisation will put a nuke in LEO and explode it at sufficient altitude to do widespread damage to electronics and power and communications grids.

All they have to do is give their payload sufficient velocity to get up there and as we are seeing with the likes of Virgin Galactic comercial organisations are looking to get significant payloads out of atmosphere and in some cases atleast as high as the International Space Station.

Look at it this way "where ever people go terrorism can go". And if you think it's credible then you would highlight it.

Me personaly I would atleast like people to start talking realisticaly about what we are going to do should a large rock come our way. After all it has happened in tha past so in all probability it will happen again, and some people think that like super eruptions we are overdue a visit from a very large lump of rock...

Evan HarperJune 29, 2010 12:21 PM

Bruce, we need to fight the terrorists up there so that we don't have to fight them down here.

peteJune 29, 2010 12:22 PM

Maybe you should reintroduce your "In the Doghouse" category again - with respect to bad security instead of bad cryptography.

JBJune 29, 2010 12:22 PM

It's long been know that when a movie series can't come up with any more new ideas, they just put the characters in space (think _Friday the 13th_)--is the same true with movie-plot threats?

Angel OneJune 29, 2010 12:22 PM

Bruce: Do you ever worry that by constantly reposting snippets of articles you're just drawing more attention to these nutcases?

Brandioch ConnerJune 29, 2010 1:10 PM

"The author clearly has no concept of the distinction between "terrorism" and "warfare"."

Read the article. It's even worse. Here's an example:

"The fall of the Iron Curtain as well as events as 9/11 in 2001, the Madrid and London bombings of 2004 and 2005 and the tsunami disaster of 2004 led to a re-thinking of the traditional perception of “threats” and “security”."

War / Terrorism / Natural Disasters, they're all the same to the author.

Carlos GomezJune 29, 2010 1:25 PM

Citizens of Cincinnati, we are being attacked by the godless... tornadoes!

Saint AardvarkJune 29, 2010 1:32 PM

@Brandioch Conner: or this one:

"A series of attacks could result in an incapability
of armed forces or mass panic: starting with the
blinding of a signal intelligence satellite, which
in turn will be unable to indicate the destruction
of a military communication satellite, leading to
an incapability to monitor any battlefield, being
followed by a destruction of the available
launch facilities, making the replacement of the
destroyed satellite impossible. Hence,
terrorists can achieve their main objectives of
mass casualties and long-lasting psychological
effects by engaging in space terrorism."

Just how exactly does that sequence of events lead to "mass panic"?

Brandioch ConnerJune 29, 2010 1:50 PM

@Saint Aardvark

How about this gem:
"The fourth and probably most destructive possible measure against satellites is a nuclear explosion at an altitude of 250 kilometres in LEO, creating an intense electromagnetic pulse (EMP) and destroying all unshielded satellites in line of sight of the explosion. In addition to that, the radiation environment would make communication between high altitude satellites and their ground station difficult if not impossible for months or years. Given the effectiveness of an EMP attack this would probably be the method terrorists would favour, provided that they had a nuclear weapon and a medium-range missile to launch it."

Because the FIRST thing a terrorist with a nuke is going to think about attacking will be satellites.

Oh, and the author got EMP wrong. It's an expanding sphere so the power drops off real quick.

paulJune 29, 2010 2:10 PM

Space terrorism is really cyberterrorism in disguise. All of those satellites are controlled by ground stations. So all network-connected parabolic antennas must be abolished.

kiwanoJune 29, 2010 2:26 PM


The rocks don't prefer hitting the moon, there just aren't any winds, rains, oceans, organisms, etc. to wash away, blow away, or otherwise conceal the craters left by the rocks that hit there.

..oh, I forgot volcanoes, earthquakes, and other geological activity too..

Davi OttenheimerJune 29, 2010 2:30 PM

So many flaws in the analysis it's funny. It reads like an Onion article. It also lacks historical accuracy. That's not so funny.

"China is often discussed as a new Soviet Union"

The CIA files just released show US policy makers have debated how China is a threat like the Soviet Union since the 1950s. It manifested in the 70s under Ford after Nixon lost control, and then resurfaced again when the Ford crew returned to office in 2001.

It seems to me an obsessive fear of China by the Cheney family (yes, the whole family) seems to have been one of the key reasons the US was steered blind through threats like international radical Islamic movements. China should be thought of as a threat under current terms, not from a 1950s view of Soviet rule. This reminds me of mistakes made in the Spanish-American war...

Anyway, back to the analysis -- ignoring the difference between possible and probable can be fun. Easy to see how launching a nuclear weapon into space is always the preferred method provided someone has "a nuclear weapon and a medium-range missile to launch it".

Using this approach the next preference for terrorists could easily be to send orange aliens with destructo-ray guns (provided they have orange aliens with destructo-ray guns).

Darth VaderJune 29, 2010 2:58 PM

The author speaks true words. We actually are having several terrorist attacks from those vicious Rebels trying to destroy our space facilities.

BobJune 29, 2010 3:03 PM

I don't understand how people don't take this hazard seriously. There is a great deal of evidence that space-based terrorism has already occurred, as demonstrated in documentaries such as "Godzilla vs. Megalon," "Godzilla vs. Mechagodzilla," "Godzilla vs. Monster Zero," and even in the recent "Godzilla Final Wars". All that would be required for the destruction of Western democracy by rampaging space monsters could be readily accomplished by disaffected Islamic militants connecting with the Cockroach People of Spacehunter Nebula M. It is amazing to me that the world's political leaders have not awakened to this imminent threat.

SteveLJune 29, 2010 3:11 PM

Subverting civilian GPS could be productive, but you don't need to faff around with satellite attacks, not given civilian (and all non-military) GPS receivers can't authenticate the (unencrypted, unsigned) signal. The ACM risks digest has a good history of GPS failures, usually accidental. the EU Galileo GPS equivalent will have authentication (presumably at a price), so their receivers should be less vulnerable.

John FJune 29, 2010 3:47 PM

@SteveL: Subverting GPS might be productive, but if you really want to induce panic, knock down the satellites that are carrying TV feeds.

Americans can, for the most part, live without GPS. But take away Sponge Bob and American Idiot^WIdol and you'll have rioting in the streets.

TankJune 29, 2010 4:04 PM

I just think the United Nations should impose sanctions on AQ that will curb their (obvious) space-based ambitions.

That is all.

RHJune 29, 2010 4:51 PM

"the deliberate creation and exploitation of fear through violence or the threat of violence in the pursuit of political change (…) specifically designed to have far reaching psychological effects beyond the immediate victim(s) or object of the terrorist attack."

I love how the article defines which meaning of terrorism they are using, then forget to actually show why their scenarios lead to any form of terror.

Now, granted, knock out all GPS satilites, and you'll have panic as millions of Americans don't know where they're going without their TomToms giving them play by play directions =p

I can see the news now: "North Korea shot down one of our military spy satelites today. We just thought you'd like to know. In other news, the leaders of the North Korean government were all found dangling from their boxers held high on flagpoles. The president of the US had no official comment, but could be heard snickering for hours."

Clive RobinsonJune 29, 2010 4:51 PM

@ Steve L,

" the EU Galileo GPS equivalent will have authentication(presumably at a price), so their receivers should be less vulnerable"

Not really.

There are a number of ways to attack all GPS systems irespective of if they use authentication or not.

To understand why you need to know not only what you are measuring but at what point.

Put simply you are measuring the distance between your GPS receivers ANTENNA and a number of satellites. Not the receiver and the satellites.

This is done not by actually measuring distance but by measuring time in the form of differences or delays between each satellites signal.

Now it is important to understand that within reason once the signals have left the physical antenna and entered the feedline the differences between the signals remain constant.

So if you had your GPS receiver in the middle of a large field and the antenna connected via a very long transmission line then to a person reading the GPS display sees the position of the antenna as a second person moves it around.

No one way signal with authentication can stop this all it can detect is time differences between it's internal clock and the primary satellite time. Which in most GPS's is fairly irrelevant as the internal clock is auto syncronised to the satellite time.

Now the transmisson line does not have to be real coax or anything like that. It can infact be an on frequency repeater via band transposition.

That is you set up your 2GHz antena and very low noise high dynamic range band amp and feed it into an appropriate mini circuits balanced mixer and take the output at say 10GHz. You amplify this signal to say 100mw using a linear amplifier, and feed it to a high gain antenna (2ft/60cm dish or horn antenna).

Line of sight to another dish of the same size 100Km is achivable. You then down convert the signal back to 2GHz and amplify it to a watt or two of power and feed it into a medium gain antenna pointed directly at the target GPS antenna.

The result is that the target GPS system will see the repeated signal not the actual signal and thus will see satellite time differences relevent to where the repeater systems input is that could be many many Km away from where the GPS unit actualy is.

I demonstrated this attack years ago as a way of demonstrating that you did not need to know the "secret code" of the military GPS signal to attack the system. Thus using it alone for guided munitions was not wise. As you will probably appreciate I did not make myself popular.

RHJune 29, 2010 5:03 PM

I wonder if Terrorism defeats itself. If our politicians overuse it enough ("If you don't pass this new tax code, the terrorists will win"), maybe they can simply take the terror out of terrorism.

CourierJune 29, 2010 5:03 PM

This is hilarious. In many ways you're lucky you don't reside in the UK where paranoia around the 'terrorist threat' is used by the police to justify all manner of privacy eroding legislation.

Clive RobinsonJune 29, 2010 5:16 PM

@ Brandioch Conner,

"Oh, and the author got EMP wrong. It's an expanding sphere so the power drops off real quick"

Sorry yes, no and not that important.

Yes : I would agree the author made a very good effort at confusing the reader about what he was talking about.

No : I would disagree with your expanding sphere. Whilst it is true of free space, 250 Km up is most definitely not free space as far as RF is concerned.

Finaly the power drop off is not as important as you might think. Whilst most electronics needs a considerable power density to be damaged (upwards of ten volts per meter) High gain broad band RF front ends are way way more easily damaged and for some low noise systems less than one volt per meter can do damage with a sufficiently fast rising edge.

Most satellite RF front ends have protection against the effects of solar radiation, however

gregJune 29, 2010 5:25 PM

@Clive Robinson

I came up with something similar a while back (after you no doubt, as at the time it was "known"). However it is easier, even with wideband stuff, to jam it with "noise" (We used "random" m/gold codes that was tuned to work best against gps). Well we found it easier...

There is a possible fix, if the wide band signal is wide band enough that its not practical to use a "repeater". like UWB stuff for example.

Also the receiver, if detecting 2 signals, should always pick the "newest" signal (time wise). We where able to pick up the newer signal at -35dB with only moderate equipment. If you assume there is an attacker, then you subtract your first high energy signal....

bf skinnerJune 29, 2010 5:48 PM

"where's the KaBOOM? There was supposed to be an earth shattering KaBOOM!"

Look our real space threat is the unconscionable provocation we are giving to space peoples. Mars we're bombarding with robot hoards collecting intel and billion dollar impactors. The rest of the planets we're spying on (an obvious first step before any invasion) we are polluting the rest of the universe with rebroadcasts of Glenn Beck.

Should we be surprised or hurt that after all this blatent incitement that Worsel the Velantian comes out and says "You kids keep the noise down. Some of us are trying to sleep!"

Dom De VittoJune 29, 2010 6:32 PM

This is a real threat!

I saw a documentary once where an enourmous maid-shaped spacecraft was sucking all the oxygen from the planet.

It's clear that space-science is not far from making this possible - unless we act now!

tensorJune 29, 2010 8:08 PM

My favorite quote, so far:

"A second category are laser attacks on satellite sensors. This could be either a direct energy weapon, interfering or damaging the satellite sensor, dazzling by swamping a satellite’s optical sensor with light that is brighter than what it is trying to image or partial blinding, i.e. sufficiently high intensities laser light which permanently damages the sensors of imaging satellites. In addition to that laser can melt material or fragile electronic connections just as it can produce thermo-mechanical stresses and structural damage."

Yeah, terrorists are going to obtain and expend the resources required to project a laser 150 or more miles into space from the surface of the earth, instead of just setting off bombs in subways or whatever. This is another movie-plot scenario, usually with a guy named Blofeld as the villain.

Since no one else here has yet said it, I'll go: the author is not exactly a rocket scientist.

JonSJune 29, 2010 8:58 PM

But ... but ... what if Al Qaida infiltrate a pregnant jihadist into the NASA Astronaut Training Program, and then she has her baby on the ISS, and then the baby spends the next 20 years on the ISS, and then the baby creates Teh Terra!!1!

J. SpicoliJune 29, 2010 9:00 PM

Spaced terrorism? Is that where, like, Cheech and Chong could put a bomb in, like, a satellite disguised as an ice cream truck? Well---dig this, now, man---nobody would CARE, because theyd all be, like, too BOMBED already! Yeah. Yeah, I can see that scenario, man. Well, don't worry, dude, the government is gonna spend a LOT of money making sure that DOESN'T happen, because if our satellites get knocked out, nobody would be able to watch Billy the Exterminator or Fox News and there'd be, like, RIOTS, man!

Clive RobinsonJune 30, 2010 1:03 AM

@ greg,

"I came up with something similar a while back"

It's the fun part of bein an engineer 8)

"However it is easier, even with wideband stuff, to jam it with "noise" (We used"random" m/gold codes that was tuned to work best against gps). Well we found it easier.."

Yes the lowest jamming margin is when the jamming signal looks like a real signal to the front end of the receiver under attack, especialy with the so called "below the noise floor" systems such as low power Direct Sequence Spread Spectrum (DSSS) systems.

The solution to this sort of attack is to have a high front end dynamic range and the ability to "track and ignore" non autheticated signals. This is two whole extra dimensions in receiver complexity.

Some years ago when designing a DSSS system for other lower frequencies I eneded up using "transmiter output" transistors as the RX front end running in class A at 28V with a half amp standing current for the prototype (not exactly efficient or light but it got the job done just). Likewise the despread (deconvolving) mixer was a passive high level device with LO power of +28dbm. And it was not really upto the job even wih appropriate antenuator pads and filters on the LO and RI.

Thankfully these days there are now high level high frequency D2A convertors with enough bits that mean you can do the whole despreading in software.

The next trick is to work out if the signal you have despread is legitimate or not and then what to do with it.

With a simple unmodulated SS signal such as your jammer would produce that is not trivial but doable. It's a whole order more difficult with a time delayed fully legitimate signal.

Also your Rx needs to be multi channel, with each channel being fully independant of the others. In many "comercial GPS receivers" this latter point is not true which allows certain other attacks that mess with the SS detect gate to work.

Usually the "commercial" GPS receiver designers make the mistake of assuming that any signal that despreads is from a legitimate satellite and thus can be used as a timing refrence to make detection of the other satellite signals easier...

So if you put out a strong DSSS signal with the right "chip code" but use an unstable "chip rate" the commercial GPS will lock onto this and use it as the timing refrence which means it cannot lock onto the lower power legitimate signals due to having the "fast/slow" synthetic streams modulated by the unstable chip rate of your fake DSSS signal....

As you say,

"Also the receiver, if detecting 2 signals, should always pick the "newest" signal (time wise). We where able to pick up the newer signal at -35dB with only moderate equipment. If you assume there is an attacker, then you subtract your first high energy signal..."

Is true and a working strategy if the receiver can detect the much weaker "newest" signal. It is due to this very issue the planed GPS upgrades involve upping the output power by quite a large margin.

However if the "repeated" signal has a sufficiently high noise floor then it still prevents the "newest" signal being detected. The DSSS "code gain" is usually given as "chip rate / data rate" which is aproximatly 1e6/1e2 = ~40db, BUT only realy applies if the receiver can first get a lock which means that if you can mess with the DS detect gate (and there are ways) your jamming signal will probably win.

However you end up in the ECM/ECCM/ECCCM.../EC...CM spiral, which gives rise to another issue nobody is currently talking about,

COTS GPS receivers are issued to the military as part of the "efficiency doctrine"... However as I have indicated "commercial GPS receivers" invariably don't have any ECCM but do have "short cuts" that make the attackers ECM job oh so much easier.

And it appears there is now a market for GPS "spoofers" with product comming out of the old CCCP/USSR.

Now ask yourself a question, imagine you are a "GRUNT" and your military GPS is not functioning (because it's ECCM is telling it it's being spoofed) you pull out your own personal GPS you bought to get through training etc that has never let you down which says you are at X. Which are you going to belive especially with the bad reputation most Mil electronics has?

By the way there is a partial solution possible by playing with the SA code and using a "differential GPS" corrector but it has significant downsides for other users world wide.

Clive RobinsonJune 30, 2010 3:45 AM

@ kiwano

"The rocks don't prefer hitting the moon..."

Have a look at "Earth in the cosmic shooting gallery"

It's a statistical model of the number of impacts etc.

One thing it shows is the apparent lack of earth strikes compared to moon strkes based on their comparative size ratio (13.5:1).

There are other bits of info out there that indicate the same.

All of which might just indicate that the earth currently has a lucky (avoidance) streak...

Or if you prefer a statistical outlier...

gregJune 30, 2010 4:05 AM

@Clive Robinson

Yet more reason why i get surprised that folks don't learn traditional navigation skill. ie a Solider that can't find his/her position on a topo map with a compass, or even some friends who have a captains certificate and don't know what a sextant is! If their GPS batteries die........

Mike BJune 30, 2010 7:36 AM terrorism is REAL. Do you know how much damage a colony drop could do to the Earth?!?! We have to stop the Zeon terrorists before they get too powerful!

ThomasJune 30, 2010 7:59 AM

Well, in my opinion she mixed up the two phrases "space tourism" and "space terrorism" and became scared.

mcbJune 30, 2010 8:12 AM

From the "maybe something got lost in translation" file:

"Space-terrorists lacking any space assets cannot be deterred through space-based weapons."

Are we sure this isn't a severely elaborate spoof? A honeypot for cynics inclined to vocal criticism maybe? A rejected Onion article?

David ThornleyJune 30, 2010 9:29 AM

Sounds like somebody needs to read the definition of "asymmetric warfare" and meditate on it for a while.

Terrorists also try to make economical use of what high-tech stuff they can get. If al-Qaida had a nuke, would they (a) explode it in space, to disrupt TV shows and GPS, or (b) explode it in New York City or Tel Aviv? Which would cause more terror?

bitmongerJune 30, 2010 9:39 AM

Ok, I didn't read much of this. I tried its nonsense for the most part. The technical skills required for these things could be put to more destructive use other ways for the most part. This does article not seem like it understands Terrorism. Like others have commented its more about warfare.

However, it lead me to thinking...

How many satellites could be deorbited by an skilled party?
It seems like those defenses might be largely
How much warning would there be?

All in all, this still seems unlikely, but at least if someone could de-orbit a lot of satellites it might then be effective from a terror prospective even if it did almost no damage just because its impressive and unexpected.

I don't think its something terrorism people should worry about, but I wonder: how much focus security gets from the least secure satellite maker?

Clive RobinsonJune 30, 2010 10:47 AM

@ Thomas,

"Well, in my opinion she mixed up the two phrases"space tourism" and "space terrorism" and became scared"

Close but no cigar, if you examine the history of terrorists since the 1970's they have predominately attacked tourists or tourist related infrestructure like "transport". As I noted above several companies are racing to bring the price of space tourism down to mass market prices...

So in all seriousness I expect space tourists to get attacked by terrorists at some future point in time

(walks off stage left to the clink clink clink of large crystal balls gently knocking together ;)

anon anonJune 30, 2010 12:40 PM

1. Obviously this guy has read that great documentary "The Moon is a Harsh Mistress" on how the lunar penal colony used rocks to terrorize the United Nations into recognizing them as a free and sovereign country! :)

2. The good news is there's a 75% chance asteroids will hit water, not land, thus missing all the cities. The bad news is - that's the worst place for them to hit - turns out a ground strike causes less damage overall than a water strike. MIT's Project Icarus looked at potential meteor strikes back in either the 60's or 70's.

BF SkinnerJune 30, 2010 1:54 PM

@anon anon "The Moon is a Harsh Mistress"

Is about as clear a manual for instructuting a moon colony in the methods of subjugating the earth. It's a cookbook that revolutionaries could easily use and get via the internet.

Obviously we must pursue people who write such things. Only by having no information available on any subject can we prevent it from being used against us by those who hate our gravity.

MailDeadDropJune 30, 2010 10:01 PM

re: GPS attacks
I've often thought that lofting a couple dozen helium balloons carrying (solar powered?) GPS jammers from the US west coast would be a fairly effective, inexpensive, easy to get away with, and difficult to counter way of screwing with the US economy. Since there seems to be a couple GPS experts here, am I off in movie-plot-land, or is there merit in this idea?

gregJuly 1, 2010 5:16 AM


Such a thing could work... but probably not for long. One thing i left out of the "easier to jam" was that once the enemy knows your jamming, they can often find the jamming signal and physically locate it.

Adding extra "multipath" signals as Clive suggested may work better since receivers don't stop working, but present incorrect data. This could be done via one balloon transmitting directly to another balloon.

note that if you want this to work for military grade GPS you need to do it for both the civilian band and the military band too.

All in all quite a bit of work, you don't know where the balloons will go. And anything that really need to know where it is, has multiple backup systems. So it won't affect anything much of a competent "enemy" IMO (assuming it works). For example munitions also have a INS for backup as well. Jamming GPS only losses a bit of accuracy.

anonJuly 1, 2010 3:39 PM

@ St. AA

"A series of attacks could result in an incapability
of armed forces or mass panic: starting with the
blinding of a signal intelligence satellite, which
in turn will be unable to indicate the destruction
of a military communication satellite, leading to
an incapability to monitor any battlefield, being
followed by a destruction of the available
launch facilities, making the replacement of the
destroyed satellite impossible. Hence,
terrorists can achieve their main objectives of
mass casualties and long-lasting psychological
effects by engaging in space terrorism."

Nice catch ... I can't be bothered to read through that drivel.

The author is seemingly stringing together a series of increasingly improbable attacks in a way that is not only illogical, but ultimately accomplishes nothing.

If you're capable of destroying a country's launch facilities, how is that strange string of satellites going to stop you? If a military communications satellite is destroyed, do we really think the only way we'll notice is with a signal intelligence satellite (whatever that is). And what battle field are we talking about? Unless these are the battle plans for Cuba's secret Operation Destroy Cape Canaveral.

AndrewJuly 2, 2010 2:35 AM

Did you NOT learn the lessons taught by our brothers and sisters on Battlestar Galactica?

MailDeadDropJuly 3, 2010 7:41 AM

@greg (re: GPS attacks)
Oh, I fully understand that such a plan wouldn't be effective against military-grade GPS receivers. But that's not my target. There are a great many civilian GPS receivers involved in day-to-day US economic activity: trucking companies, civilian aviation, parcel delivery services, etc. I'm proposing to disrupt those activities through denial-of-service attack on the GPS signals (straight jamming, no spoofing attempted). Using weather balloons puts the jammers safely out of reach (weather balloons trivially reach 60,000ft altitude) *and* provides nice signal footprint for them. By virtue of being at least 20x times closer than the actual satellites, their signal strength will proportionately stronger (and therefore more effective at jamming). And by launching from the US West coast, the prevailing weather systems will push them across the entirety of the contiguous US. The things I don't really have a handle on are: 1. Is the energy budget of a simple GPS jammer low enough that a balloon-lofted payload could operate it continuously for a week or more? Is solar supplementation an effective option? 2. What are the costs in lofting dozens of one-week-lasting weather balloons? 3. What, if anything, are the immediate counters to such an event? (i.e. once the balloons are up, is there anything that could be done other than waiting for them to fall from the sky or mounting guns on U2's ?)

GregJuly 4, 2010 4:39 AM


All sounds very plausible. The transmitters can be on the oder of grams, so all your payload can be for power--even cheap, heavy lead acid gel cells would give a decent life time (you could afford the weight). LiH cells and your going to be limited by the balloon loosing gas.

Generally speaking much of the "advanced" technology often has a pretty simple counters.

As i said before. I am surprised how many folks (even sailing boats) don't bother to learn proper navigation. After all we have been navigating the globe for much longer than we had GPS, and all you need is flat batteries for GPS to fail.

Clive RobinsonJuly 5, 2010 2:53 PM

@ MailDeadDrop,

"'I'm proposing to disrupt those activities through denial-of-service attack on the GPS signals(straight jamming, no spoofing attempted).

You first need to consider the jamming margin which is aproximatly the chip rate over the data rate or 1e6/100 for the civ GPS which is 10000.

Or 40dB your "straight jamming" or "CW" signal would have to be above the power sum of all the satellite signals at the receiver antenna. Plus a further 12dB margin just to throw any receivers that already have a track on a satellite.

"Using weather balloons puts the jammers safely out of reach (weather balloons trivially reach 60,000ft altitude)."

Yes they do but only with one or two Kgs load tops. which means that height might not be your friend in what you hope to achive.

Put more simply each 6dB effectivly doubles your range in freespace (which the uper atmosphear is not). So as a crude aproximation 52/6 gives you just under 9 times so say your ballon needs to be 10% of the distance from the closest satellite as a maximum when pushing out the same ERP at 19cm wavelength.

I'll leave it to you to look up the GPS ERP and altitude, and do the appropriate conversion for power and thus weight.

It is this consideration that has made NASA amongst others look at using "Solar Gliders" that is glider aircraft with an electric hold motor and solar pannels as wing surfaces. For anything over a few minutes of doing what you are thinking.

Mind you one of those 70ft blimps that Kent (UK) Police are thinking of using with a top skin of solar pannels at 20,000ft might well be a quite workable solution ;)

Clive RobinsonJuly 5, 2010 4:17 PM

Oh dear I can't believe I typed,

"Put more simply each 6dB effectivly doubles your range in freespace (which the uper atmosphear is not). So as a crude aproximation 52/6 gives you just under 9 times so say your ballon needs to be 10% of the distance from the closest satellite as a maximum when pushing out the same ERP at 19cm wavelength"

Ho hum it should be,

... 52/6 gives just under 2^9 times so say ballon needs to be 1/512 of the distance from the ...

That is for the same ERP the CW jamming balloon at 60,000ft is about 18.5Km up and the corresponding satellite hight with a DSSS signal would need to be at a minimum of 9,450Km up...

The moral don't type on your mobile whilst train hopping to try to get home a little quicker...

RobertJuly 5, 2010 10:42 PM

I doubt this simple inband CW attack would work on any modern well designed GPS receiver. to make it work you would have to induce non-linear effects in the LNA. Otherwise the Digital filters would simply notch filter the CW. So unless you saturate the LNA or induce clipping in the ADC I think your CW attack is wishful thinking. The problem is that modern Soft radios using sigma delta ADC's have too much dynamic range, on older generations of receivers you could jam them with CW because the CW signal spoofs the Rx AGC, forcing the actual GPS Rx signal down into the ADC quantization noise.

If I were trying to jam I think I'd try to understand the FEC coding and intentionally burst at critical times to force multiple bit Rx errors. This take much less average power than a CW signal.

jacobJuly 6, 2010 10:55 AM

@Clive, great posts as always. A couple of points.
1. Military. China would probably like to hit our GPS sats. Our military depends on it more and more. Not likely though, they have bigger worries. Al Qaeda seems to have problems covering their asses from drones at the moment. They might have problems setting off a bottle rock at the moment while ducking and covering.
2. Space based attack? What, attack the space station? seems excessive for the payback.
3. I would worry more about an EMP over the U.S. That could mess things up.
4. Space based. I would worry more about the fact that everyone at one point thought that South Africa had set off a nuke. It turned out to be a meteor. If we had a meteor explode over the M.E., that could really set people off. (Pun intended) Just my thoughts.

Clive RobinsonJuly 6, 2010 12:09 PM

@ Jacob,

Nice to hear from you I hope you are well.

With regards,

1, I'm fairly certain that China amongst several other nations has the technology to directly take a satellite out with a kinetic weapon of some kind (think a large slug of depleated uranium on top of a smallish rocket moving in a counter rotating orbit). I suspect that Japan and a number of other nations likewise have the technology.

2, Attacking the ISS is possible it's not exactly a very "robust" structure (it does not need to be). However a number of companies have"bid" to provide payload lift for resupply contracts and you are looking at unmaned auto guided delivery systems capable of getting to within 20metres or so with 10,000Kg payloads for some. Have a look at,

3, The problem with EMP is it's generaly not very directional and thus can be more trouble than it's worth. There where however some designs using sub 1KTn nukes in cavity waveguide designs. I'm not that up on the physics involved but apparently the broad band of the normal EMP pulse can be constrained in a resonant cavity which feeds a wave guide out let with a horn or equivalent antenna. The result is to convert the EMP from a broad band rapid edge pulse to a narowband burst of microwave energy at an incredably high power, all before the physical effects of the explosion destroys the cavity and waveguide. Effectivly it becomes a HERF gun of incredible power and reasonable directionality (say 10-20degree 3dB beamwidth).

4, Yup very large lumps of rock moving at sufficient speed do liberate very high levels of energy. However the energy signiture is suposed to be sufficiently different to "instantly" tell the two apart from space based observation.

The point is though the amount of energy released and where, as has been noted a lump of rock landing on land is devistating but not as much as if it lands in water sufficiently close to a shalows or bay.

Which begs the question of a cascade attack, that is a sufficiently large rock hitting the seawards facing slope of an unstable volcanic cone or island. Causing it to slide/colapse into the sea generating a tsunami of biblical proportions to hit the east seaboard of the US...

Bill-Parcel DeliveryOctober 2, 2010 7:30 AM

I think you will have to fight them on every level, Terrorists will always adapt to the situation even when technology to so advanced.

Fight them on earth and in space, then maybe the moon.

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