Lets assume i have a capital starship that needs to be made resistent to electro-magnetic attacks, either by a nuke' pulse or a by more direct way to "apply" EM (radiation) attacks - how could hardening the vessel be achieved ?

Would you add a specific element (chemical) to the outer armour layer of the ship, or would the density/thickness of the hull structure/armour determine how vulnerable the vessel would be in the first place ?.

In general, apart from directly hardening all electronics on the ship and/or adding backup Systems (would that even help?), would there be a way to generally harden a starship against such attacks ?

  • $\begingroup$ "EM" is a very broad range, going from radio-wave to gamma rays. "radiation" is even broader because it includes particles. It wouldn't be reasonable to counter all this with a single measure. I think you should specify better. $\endgroup$
    – ZioByte
    Feb 14, 2018 at 13:37
  • 1
    $\begingroup$ The planes used by the US president have shielding to protect against EMP attacks, so researching that might be a good starting point. $\endgroup$ Feb 14, 2018 at 13:51
  • $\begingroup$ You are aware "EM" includes light, right? $\endgroup$
    – nzaman
    Feb 14, 2018 at 14:02
  • $\begingroup$ @AndrewBrēza Researching that might also get you flagged by the FBI. $\endgroup$
    – Frostfyre
    Feb 14, 2018 at 15:39

6 Answers 6


A Faraday cage around your ship is your best chance, basically an outer wall around your ship made of conductive material that is separated from the rest of your ship (a composite armor made of an outer conductive material and an inner non conductive material for example), as long as there is nothing conductive that goes through from the outer hull to the inner non-conductive shell any electromagnetic wave should go through the path of least resistance and around your ship outer hull.

Note that while usually shown as a wire mesh (which does works on most cases) in fiction in order to block all of the EM wavelength possible you will likely want your cage to made of thick sheet metal, the thicker the better - the lower the EM frequency is the thicker the cage will need to be for it to block it.

If you want to be extra safe you can even create a second layer of shielding around sensitive and\or important components, the picture below shows a RL shielding of an Ethernet cable - that metal foil is there to shield it from outside EM radiation as those tend to create problems with packet transmissions.

The more you know

Now that we got the E out of EM taken care of we might want to consider how to defend the M of it as well, a magnetic wave decreases in strength very rapidly over distances so defending against the magnetic affects of an EM weapon in the distances where a space battle takes place might be a bit of overkill but if you want to you could use Mu-metal wrapped around the ship in yet another layer just to be on the safe side.

  • $\begingroup$ A faraday cage would be great for blocking attacks by weaponized radio waves and other long wavelength EM radiation. It would be hard to get the cage holes small enough to block ultraviolet or any shorter wavelengths like xrays or gamma rays. $\endgroup$
    – Willk
    Feb 14, 2018 at 14:00
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    $\begingroup$ That's why I stated that he will want to use sheet metal, no holes in a solid sheet of steel that covers the entire ship. $\endgroup$
    – cypher
    Feb 14, 2018 at 14:03
  • $\begingroup$ @cypher I think the holes are part of the design. The holes are tuned to specific frequencies. Larger holes working for lower frequencies and smaller working for higher frequencies. Would it even work the same with no holes? $\endgroup$
    – Loduwijk
    Feb 14, 2018 at 14:32
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    $\begingroup$ A very thin layer of superconducting material will completely shield the ship from all magnetic fields due to the Meissner effect. There is a consideration to be had with faraday cages though, even if it blocks electromagnetic waves from interfering with electronics, etc it still doesn't prevent the buildup of static charge, which would need to be discharged before coming to port. $\endgroup$
    – Hans Z
    Feb 14, 2018 at 15:52
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    $\begingroup$ The buildup of charge is interesting before reaching port as it would require keeping everything inside always grounded, anything that temporarily was insulated from the cage during an attack, say a person wearing shoes or jumping, would be a shock hazard. $\endgroup$
    – user25818
    Feb 14, 2018 at 17:01

I can think of 3 ways to address an incoming attack.

  • Absorb
  • Deflect
  • Allow to pass through.

    1. Absorb. A lead xray vest is an example of this. For radiation you need mass. The mass absorbs the energy of the radiation. You could have the shielding ablate away into a cloud around the ship, where the atoms of gas wil still function to absorb energy. I think a Faraday cage as proposed by @cypher falls under absorb - the energies of incoming waves of wavelengths too long to get through the cage holes are absorbed by the material of the cage.

    2. Deflect. Reflect is a subset of deflect and it is why satellite stuff is that shiny material - reflecting EM radiation to go off and do its business. This is nice in that a perfect reflector will not be ablated although no reflector is entirely perfect and will be worn away to some degree.
      A more exotic method would be to use the radiation against itself. I proposed this here: Is it safe to orbit HDE 226868? in a question about how to safely visit the vicinity of a strong xray source. Xray crystallography turns on the idea that xrays can be bounced so as to produce areas of constructive interference and destructive interference.

xray crystallography

The ship would hide in the areas of destructive interference. There would be no net loss of energy - just reallocation of energy.

3. Pass through.
In a way, being seen is an EM attack. The EM radiation striking you allows your enemies to see you and do you harm. Transparent animals sidestep this by allowing visible light to pass through.

http://www.bbc.com/earth/story/20150611-the-top-10-see-through-animals transparent butterflies

So too your ship. If it is made of materials which do not impede or stop the incoming rays, the rays will keep going out the other side, carrying their energy with them. It would take some creativity to apply this strategy to biological things but not so much to apply to mechanical things.


A capital starship could be hardened against EM attack by hardening it literally; just add more mass.

Taking your examples, I am assuming you are not including EM of sufficient power and focus to be used as a gun for destroying your ship outright (ie: high powered laser to blast through your hull), but rather for jamming, overloading via EMP, etc..

Just put enough mass on the outer portions of your ship and it will block practically all of the energy. It could be something like lead, but it could also just be water. And it does not have to be the outermost part of the ship either; it just needs to outside of where the delicate things needing protection are. You could surround only specific compartments if you wanted to: the bridge, datacenter, and a few other things.

Attenuation is the reduction in intensity of the light beam (or signal) with respect to distance travelled through a transmission medium.

The beauty of this is that it absorbs a broad frequency spectrum. If my understanding of faraday cages is correct, they will have a much shorter spectrum over which they work.

What you need to do is decide which EM frequencies are likely used in your scenario then check to see how far they penetrate into various substances. The penetration if deep enough (not blocked trivially) may be measured in some "half-distance" (analogous to radiation half-life) type of unit, generally attenuation coefficient.

So if a certain EM frequency you are worried about has a half-distance of 1 meter in water (based on its attenuation coefficient for that EM frequency), then 1 meter of water will block out about half of it, 2 meters will block 75%, 4 meters 87.5%, and so on. So you put your bridge in the middle of your water reserve so that you have 15 meters of water surrounding you and you block 95% of the energy.

At that point, if a few percent of the energy at some frequency left over is still a concern, you use some other method to absorb, reflect, or otherwise deal with the remaining bit. Such as the faraday cage mentioned by @cypher designed for the frequencies you are worried about that are still getting through a little bit.

  • $\begingroup$ There isn't really that much difference between a laser and an EMP, other than the frequency. EMP consists of a large spike of low frequency noise, while a laser is a coherent set of frequencies. Calling just one a physical weapon makes no sense. $\endgroup$
    – nzaman
    Feb 14, 2018 at 15:10
  • $\begingroup$ @nzaman You are probably right about your last sentence, perhaps I used poor wording. I think it is disingenuous, however, to suggest that a laser and emp would be comparable as weapons, especially in the common nomenclature. When people talk about a laser weapon, they are talking about something that physically destroys a target, hence my wording of "physical weapon". When people talk about EMP or other forms of electronic warfare, they are talking about ruining or misdirecting your electronic devices. $\endgroup$
    – Loduwijk
    Feb 14, 2018 at 15:37
  • $\begingroup$ @nzaman There, I have improved it. Thank you for your assistance. $\endgroup$
    – Loduwijk
    Feb 14, 2018 at 15:39

Well luckily, nuclear explosions usually only generate a large electromagnetic pulse at certain altitudes in the atmosphere. I'm no physicist, but it is caused by air molecules interacting with gamma rays put out by the nuclear detonation. If there's no air molecules, you won't have to worry about an EMP as a starship captain.

Starships also have to deal with radiation all the time, that's one of the hazards of just being in space. So EM-based weaponry and attacks don't seem like the best tool.


Let's look away from the issues with generating EMP with nukes. Assume as given, there are ways to generate EMP in space and someone in the future weaponized some of them.

Now, because I am fun at parties and 'cause it fits the question, my way of choice to protect from EMP in space is–

Spaceships with vacuum tubes!

This is a definite SciFi classic from the 50s and earlier. At that time it emerged because people knew no better. In a sense, it's a perfect example of electronics dating: mighty starships hop through parsecs, but need to punch cards to feed into their computer. Said computer spits out a continuous-feed sheet with a matrix printer at best.

It contrast to the writers from the 60s or so, we can do it deliberately. Vacuum tubes are said to be much better resistant against EMP than solid state devices. If a close EMP is an often and dangerous attack vector (and if we got nothing else to shield aside from computers), we can dive head-first into a reactors-and-turbins stylistics of the 50s and 60s.

tl;dr: Borrow the old and infuriating gap between advanced space technology and outdated computer tech, but provide a reasonable explanation for it.


The key to shielding is to be able to dissipate the charge. If the charge does not get dissipated, it just hangs around. Anyone who has shorted a fully charged capacitor knows what happens if the charge is not dissipated. Faraday cages work because they are grounded through the earth, dissipating the charge harmlessly.

For that reason, metal would not work. You would probably end up with a huge capacitor.

I suggest encasing the spaceship in something similar to a huge cob light, so the charge is transduced into a very very bright light.

Further, change the residual heat into light and you have an extremely bright ship. Maybe it can disguise itself as a star.


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