QOTW #33 – Communications infrastructure after a nuclear explosion

2012-08-24 by . 3 comments

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A few weeks ago, I was sat pondering nuclear bombs. To any of you who frequent the DMZ, this shouldn’t be much of a surprise, as it’s pretty much par-for-the-course for my imagination on a Wednesday night. I started thinking about the electromagnetic pulse released from a nuclear explosion, and how it might affect electronic devices. “But surely,” I thought, “a nuclear bomb would negate any interesting post-blast resilience implications by turning all local electronic devices into glowing dust!”. How wrong I was.

After a bit of research, I came across High-Altitude Nuclear Explosions (HANE). No, this isn’t the title of the latest Michael Bay movie, but rather the concept of detonating a nuclear bomb at an altitude greater than 30km. Whilst this might sound rather ridiculous, certain countries have actually done it. In the early 60s, the USA and Russia performed a series of HANE tests, in order to better understand the potential for anti-satellite weaponry. These tests showed that the electromagnetic pulse and ensuing radioactive fallout was capable of destroying or damaging satellites in space rather indiscriminately. The tests caused numerous satellites to fail after a short period of time, due to severe radiation damage. What’s really interesting about HANE, though, is that the explosion releases a giant electromagnetic pulse, without the hassle of re-enacting that dream scene from Terminator 2 where Sarah Connor’s skeleton is left clinging onto a chain-link fence.

To quote the Wikipedia article:

This high-altitude EMP occurs between 30 and 50 kilometers (18 and 31 miles) above the Earth’s surface. The potential as an anti-satellite weapon became apparent in August 1958 during Hardtack Teak (a HANE test). The EMP observed at the Apia Observatory at Samoa was four times more powerful than any created by solar storms, while in July 1962 the Starfish Prime test damaged electronics in Honolulu and New Zealand (approximately 1,300 kilometers away), fused 300 street lights on Oahu (Hawaii), set off about 100 burglar alarms, and caused the failure of a microwave repeating station on Kauai, which cut off the sturdy telephone system from the other Hawaiian islands.

That’s one hell of an electromagnetic pulse!

After I’d got over the initial excitement of learning that it is actually theoretically possible to sizzle microchips from space using nukes, I decided to post a question on Security SE. In short, I wanted to know how worldwide communications infrastructure, especially the Internet, was protected from such attacks. This is where our resident nuclear weapons “enthusiast” Thomas Pornin came in, with a wonderfully detailed answer.

It turns out that the Internet is, like a condom machine in the Vatican, amazingly redundant. Obviously not quite the same kind of redundant, but redundant nonetheless. If a network link goes down, packets are routed through other links. It’s a self-healing network. This means that you would have to knock out multiple inter-continental network links in order to cause severe disruption. Furthermore, it has plenty of redundant channels that are likely to still function after a large EMP:

An interesting issue with radio and satellite communication is temporary disturbance of the ionosphere. The electromagnetic pulse would cause electrons to be jiggled about in the upper atmosphere, creating areas of increased and decreased electron density. A lot of long-range radio communication relies on “bouncing” radio waves off of the ionosphere, which means that such communications are likely to suffer strong interference. Longer wavelength signals are likely to be disrupted more than short wavelength (GHz) signals, due to some interesting physics wizardry I won’t go into.

Of course, in the case of a real war, we’d have to worry about anti-satellite weapons knocking out communications too. Thankfully though, under-sea cables are shielded by a big blanket of water, which absorbs electromagnetic radiation. This is why submarines send up a radio mast or buoy. The good news is that our fastest and most reliable network links will actually end up being our most resilient, because they’re on the sea bed. Furthermore, optical fiber cable is not affected by electromagnetic induction, like copper wiring is. So, if all hell does break loose, the phat-pipes should still be able to serve you your daily dose of StackExchange! Yay!

But not everything relies on hardware interlinks. We also have to take into account the systems that facilitate the core functionality of the internet. An interesting example of this is DNS. There are thirteen root nameservers that facilitate the absolute top tier of DNS functionality. Without the root name servers, we wouldn’t be able to reliably translate domain names into IP addresses. Think of them as a set of mirrors for a global directory, where top-level domains (TLDs) are indexed. These entries point to other DNS servers, which point to other DNS servers, etc. We’re left with a large hierarchical map of DNS resolution. Now, whilst thirteen servers sounds rather flimsy, the actual number of servers involved is much larger. A neat technique called anycast allows multiple physical servers across the world to represent a single root name server. This is not the same as cloud computing, which is often touted as a panacea for uptime-critical solutions. Guess what? The cloud is not redundant! But I digress. In order to take down the entire DNS system, you’d need to nuke Japan, England, France, Germany, most of eastern Europe and the entire east and west coasts of America into oblivion. At that point, I don’t think the remaining radiation-resistant insects would be particularly interested in whether the DNS system is functioning or not.

The biggest threat HANE poses to our infrastructure is to our power grid. The world is coated with a mesh of power wiring, stretching over hundreds of miles of land. Since the cables are so long, and are very likely to cut through the magnetic lines of flux in a perpendicular manner, the induced currents could be massive. Local substations would burn out, street lighting would fry, circuit breakers would pop, and fuses would blow. Without power, our worries about communications infrastructure being disrupted would be rather pointless. The servers that host anything worth accessing would be down anyway, and it’d be likely that you couldn’t boot your PC or charge your laptop, due to lack of power. Even when sections of the power grid come back online, the demand would be massive, causing further outages and brown-outs.

So, how can we protect ourselves? Here’s a few ideas:

  • Wrap everything important in a giant Faraday cage. Not exactly practical for power plants or datacenters, though.
  • Ensure that significant chunks of the world’s communications infrastructure is built around trans-oceanic cables and optical links.
  • Ensure that nation-critical services are distributed globally, with the ability to self-heal if remote systems become unreachable.
  • Be prepared to switch to lo-tech communications in the event of such a disaster.

Perhaps the thing to take away from this analysis is that nukes are dangerous, and there’s not much you can do to prevent their aftermath. The best policy is to not detonate nukes at high altitude, or if possible, not to detonate nukes at all.

Nukes are bad, m’kay.

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  • Piskvor says:

    Although transoceanic fiber is not damaged by EMP, the optical cables contain built-in electrical repeaters, which are powered by high-voltage electricity – carried by copper wires inside the cable. The shielding provide by oceans should be sufficient for the usual depths, but the cables need to come ashore somewhere. (This is the cables’ weakness in various other scenarios as well)

  • scottpack says:

    Not only is the electrical grid fragile because of how it operates, but the North American grid is fragile simply because of bad design! Let’s not forget the Great Northeast Outage of 2003 where more than 50 million customers were out of service in Canada and the United States. All due to a single instance of over-demand from a northern Ohio generating plant.

  • Polynomial says:

    I’m not sure that a high demand would change the amount of damage done. The issue is that the EMP induces huge currents in electrical wires, especially long ones like power lines. These currents would fry substations and junction boxes. The critical factor is the density of transformers.

    If you have a very densely populated area, with industrial units, you’re likely to have a large number of domestic substations (2.4kV -> 230V) and a few larger industrial (33kV -> 400V) substations. The transformers in these substations act as giant inductors, creating a buffer. This allows the current to produce a huge magnetic field around the coils of the transformer, instead of inducing further erratic currents down the secondary lines. Even the lines themselves can store a reasonable amount of potential as a magnetic field. The smaller substations are still likely to catch fire, but they act as a temporary buffer to absorb and dissipate some of the energy as an EM field and heat respectively.

    In a less dense grid, you’ve got nowhere for the current to go. It’ll just fry the hell out of all your gear, because you can’t store enough energy as an electromagnetic field in order to dissipate it over a few seconds.

    The only time I could see load being a factor is in countries like India, where the power grid is horribly contrived, poorly designed and massively overloaded. In such a situation, everything is so poorly isolated that small shorts can knock out the power to a town, so an EMP is likely to devastate the grid.