I've been spending some time thinking about putting a satellite weapon into space. It would look something like this. Don't worry about those letters, they stand for something else.

enter image description here

This weapon can direct an electromagnetic pulse at the Earth of sufficient intensity to cripple a city. How do I provide enough power for this weapon?

The power system must be feasible with 1995 technology, able to survive in space for years to decades until called upon, and powerful enough to energize said pulse weapon.

Also, I may have other nefarious satellites in orbit, so this has to be a power source, not a bomb. I don't want to damage any of my other investments while I reduce London to ruin.

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    Your weapon would be much bigger than this. You'd need something like a gamma ray burst and from space, that would be a ton of energy. – The Anathema Sep 13 at 19:03
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    "so this has to be a power source, not a bomb" But bombs are power sources! – RonJohn Sep 13 at 19:04
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    @RonJohn Absolutely agree. They are like batteries. Limited charge capacity. It can be used until the charge is depleted (or exploded, same thing). – ArtificialSoul Sep 14 at 9:46
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    To add a bit more detail to the people saying "it has to be a bomb": Nuclear EMPs result from gamma rays produced by the bomb interacting with diffuse gas in the upper atmosphere and Earth's magnetic field. At altitudes where satellites can orbit for decades on end without maintenance, there may not be enough gas to make an EMP. So, instead, your satellite could store several nuclear warheads that it can drop anywhere on the planet. If these nukes detonate in the upper atmosphere, they'll make EMPs. And if your other satellites are in high enough orbits, they shouldn't be affected. – Someone Else 37 Sep 15 at 4:46

If you want to trigger an EMP with sufficient intensity to cripple a city from orbit, I'm sorry, but it's going to have to be a bomb.

EMPs are not efficient. You could use an directed energy weapon (probably microwaves), to disrupt specific targets - in fact, there's research into building such a weapon into a cruise missile. But your energy requirements increase non-linearly as the area you wish to affect increases. Additionally, the greater the distance from source to target, the greater the energy required. Eventually, if you're operating from orbit, you're going to need so much energy that it's more efficient just to make it a bomb.

(And, in fact, the Goldeneye weapons in the movie of the same name were single-shot bombs as well - from the James Bond wikia:

...the weapon consisted of two disposable satellites designated "Petya" and "Mischa", each one armed with a nuclear warhead. By detonating the device in the upper atmosphere, a pulse or a radiation surge, is generated; capable of destroying all electronic devices in a 30 mile radius.


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    It seems that ability to focus the energy matters as well. My flashlight that uses 3 D-size batteries can light up the entire opposite wall of a room, but outside, I still can't see very far down a trail at night, for example. However, the laser pointer I annoyed my with uses a single button battery, can be seen reflecting on something hundreds of feet away, but only a coin-sized dot, no bigger. In other words, if I can restrict the "Goldeneye" beam very narrowly, I might not need as much energy at the source. I admit I'm not sure, but this answer feels incomplete without addressing it. – cobaltduck Sep 13 at 18:53
  • It's true that you can restrict the beam (as in the directed energy weapon I linked in the second paragraph), but in that situation, you're not fulfilling the OP's desire to cripple a city. Collimation of an EMP is also somewhat impractical, as the chaotic nature of the field is what does the damage to electronics. You can do damage with focused VHF or microwave beams, but it has to be very targeted. – jdunlop Sep 13 at 18:58
  • Can't believe I omitted the word "cat" as in "annoyed my cat with" Too late to edit, also. – cobaltduck Sep 13 at 19:00
  • "energy requirements increase non-linearly as the area you wish to affect increases". But doesn't area increase non-linearly? – RonJohn Sep 13 at 19:05
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    @RonJohn. It does, but EMP (even directed) affects a volume, rather than an area. So it's geometric in proportion to area, as well. – jdunlop Sep 13 at 20:14

Since everybody loves math as much as I do

Here is some math

Geosynchronous orbit (GSO) is ca. 36,000km altitude.
Earth radius is 6,371km.
So distance to a satellite is about 30,000km.

The area of your target (London) is 1,572 km².

Imagine a nuclear bomb being set off at GSO. The blast would spread in all directions. So the portion that would be directed at London (if it was directly above London) would be $$R = \frac{A_{\text{London}}}{A_\text{Sphere;30000km}} = 1.39 \times 10^{-7}$$ or as a solid angle of $$\Omega = \frac{A_{\text{London}}}{(30,000km)²} = R \times 4 \pi = 1.75 \times 10^{-6}$$

That would be the focus a weapon would need. It's quite narrow, but a laser should manage to achieve that. (I am not a laser specialist, but I am certain that should work.)

What radiation passes through the atmosphere?

atmospheric attenuation Microwaves pass through the atmosphere with only slight issues on some wavelengths. So we can assume they reach the surface just fine without accounting for further attenuation. (That is a simplification. There is some radiation blocked, but we're gonna ignore that. It's not that much.)

(High-Power Microwaves (HPM)) achieve a similar effect to EMPs, but are more difficult to harden against. Unfortunately, a big part of an EMP by nuclear explosion is caused by ionization of the air by gamma radiation. That radiation would mainly be absorbed by the atmosphere and would not reliable reach the target ground. At least not at high efficiency.
So we'll stick with an HPM concept for now.

The Non-bomb weapon

Information on how much energy is needed for a HPM to work is hard to come by. Bofors HPM Blackout is a weapon like that. Unfortunately, we don't know how much energy it needs. Just that it wighss less than 500kg.

Nuclear fission bombs range from under a ton to more than 500,000 kiltons of TNT. All of the sizes cause an EMP. - Obviously at different magnitudes. These sizes range from 4.2 GJ to 210 PJ energy output. In a nuclear explosion this energy is manifesting in several different ways. EMP, Air blast, Heat, light, etc.. Not all of those things would be useful for the desired result, so we would need less energy, if we manage to concentrate it.

But overall we would still need at minimum several GigaJoules of energy to reliably fry circuits in the target area.

How would you store this amount of energy electrically rechargable in a satellite with 1995 technology?

You couldn't. First of all until that would be charged using solar panels would probably take quite a while, unless your satellite is more than space station size at 230 W/m² for solar panels.

And how would you store that energy?

Well, considering there are no battery concepts now with more than 5 MJ/kg (Link in German because of a significantly more detailed list) you would need many tons of batteries.

And the additional problem of radiation hardening. To my knowledge batteries are not that fond of radiation, so having them out in space would require significant mass to protect them from it.
Even if the radiation wouldn't destroy them, it would probably lower the capacity over time as well as make it lose energy, making your recharging even more a problem.


I doubt it is possible. Maybe today with High-End secret military projects, but not with anything normal I could find.
But with 1995 technology it is even less likely.

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    "And how would you store that energy?" A bomb!!! :) – RonJohn Sep 14 at 12:55
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    @RonJohn Bombs would certainly make that easier. – ArtificialSoul Sep 14 at 12:57

The ionosphere will power it.

Lightning is a natural cause of electromagnetic pulses. These natural occurring EMP pulses can do significant damage to electronics on the ground. http://www.alphamarinesystems.com/lightning_and_emp_damage.htm

The ionosphere of the earth carries a high electrical charge. This charge builds up because the atmosphere is a good insulator, preventing the charge from going to ground.


Global current The potential difference between the ionosphere and Earth’s surface is approximately 250kV (2.5 × 105V). This very large potential difference means that the charged ions in the atmosphere will move and thus produce a vertical current.

Your Goldeneye capitalizes on this. It first emits a gas which diffuses out in a large radius, quickly becoming conductive plasma. Then it fires a "rod from god" orbital weapon from its onboard railgun (powered by a solar charged capacitor). As opposed to the typical role of these weapons to traverse the atmosphere intact and deliver a massive kinetic punch, this rod is made of silver and is intended to ablate on the way down, shedding particles and silver plasma en route. It will take it 20 seconds to make it to the ground.

But it will not reach the ground - the rod will ablate to nothing before making impact. It does not have to. Behind it, the immense charge coming down the conductive path of plasma will complete the process, arcing across the remaining atmosphere to ground and delivering an immense electromagnetic pulse.

Goldeneye produces a lightning bolt from the ionosphere. There is a lot of ionosphere. This trick will work more than once.

I have seen a video of lightning called down along a rocket-lifted copper wire. The portion along the wire was green, probably from the copper plasma. I am not sure what color silver plasma would be.

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