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High altitude nuclear explosions will completely render electronic devices on the ground useless (unless protected, with lead coating for example).

How are satellites affected by such explosions?

With how the satellite density has increased since the ban on nuclear tests, I'm assuming a few would be affected.

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    $\begingroup$ The title says "on the ground" but the body says "high altitude". Which one are you asking about? $\endgroup$ – Organic Marble Apr 16 '20 at 17:44
  • $\begingroup$ @OrganicMarble The high altitude was about their effects on the ground instruments, as such tests have been conducted before. The question is about an explosion anywhere, but specifically on the ground, since that's where it's most likely to be detonated. I edited the question to reduce the confusion $\endgroup$ – Speedphoenix Apr 16 '20 at 18:16
  • $\begingroup$ I'm still confused but you may enjoy reading about Starfish Prime en.wikipedia.org/wiki/Starfish_Prime $\endgroup$ – Organic Marble Apr 16 '20 at 18:31
  • $\begingroup$ there is some potentially helpful information in this and this answer $\endgroup$ – uhoh Apr 17 '20 at 3:12
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    $\begingroup$ @OrganicMarble: I was expecting the user StarfishPrime to mention Starfish Prime. ;^) $\endgroup$ – DrSheldon Apr 17 '20 at 17:11
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The linked Wikipedia article discusses the effect of the electromagnetic pulses produced by the blasts.

unless protected, with lead coating for example

The electromagnetic pulse is like a radio wave, not ionizing radiation. You need extremely effective electrical shielding not radiation shielding.

This answer to Would astronauts on the ISS be affected by the radiation from a global nuclear war? and to a lesser extent this answer to Can people be in orbit around Mars were they to blast the poles with Nuclear bombs? discuss the phenomenon.

As explained in the link above and here if a deliberate EMP device was used, the burst would be at high altitude in the atmosphere or in space. The prompt gamma ray pulse propagates to the thicker atmosphere where the electrons in the atoms of the atmosphere all jump at once, producing a lower frequency electromagnetic transient. That will propagate back up to the ISS' 400 km and if it's passing over the footprint of the EMP device it may get zapped.

In your example the blast is at the surface so that's where the EMP would originate.

Briefly, the intense gamma ray burst knocks electrons out of atoms in the atmosphere via Compton scattering and the sudden pulse of those electrons makes an electromagnetic wave a bit like a radio wave except very short and broad in frequency.

This is picked up by wires and electronics and makes a current that tends to burn out devices, especially semiconductors.

Satellites in LEO that are passing overhead will receive this electromagnetic pulse but it's really hard to say how many or which ones would be affected; technology gets better over time.

With how the satellite density has increased since the ban on nuclear tests, I'm assuming a few would be affected.

This could be the case.

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    $\begingroup$ Thank you the lead coating example came from a work of fiction where vehicles that used lead to protect the electrical components where the only ones usable after a high altitude nuclear explosion. I guess that's a pretty bad source. Is it possible to know the radius of the zone in which satellites would be affected? (or angle of the cone) $\endgroup$ – Speedphoenix Apr 18 '20 at 14:35
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    $\begingroup$ @Speedphoenix oh that's different! In a high altitude explosion satellites may be exposed to much more direct ionizing radiation like gamma rays and neutrons and all of the charged particles these then put into the magnetosphere! Your question is about detonation on the Earth's surface. My linked answer says I don't think much prompt radiation (gamma rays) makes it through earth's atmosphere, which has an areal mass density equivalent to 76 centimeters of mercury and it would shield space from the surface about as well as the surface from space $\endgroup$ – uhoh Apr 18 '20 at 23:28
  • $\begingroup$ Yes, a high altitude explosion is much more likely to take out lots of satellites both from prompt radiation and from the ionized particles now trapped in Earth's magnetic field for a while, which satellites will continue to "swim in" for a long time afterward. $\endgroup$ – uhoh Apr 18 '20 at 23:31
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Only satellites with a direct line of sight (LOS) to the explosion are likely to be affected. These satellites will get hit with the photon and high-speed particles emitted from the explosion and almost certainly the radiation levels will overwhelm all shielding and rad-hard parts.
I believe it was in Sum of All Fears that Tom Clancy described such an event. While that was fiction, he generally used solid scientific bases for his novels.

The radioactive "dust" and stuff from the explosion does not get very high in the atmosphere, so most likely all other satellites will not suffer any effects from the explosion.

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  • $\begingroup$ It was sum of all fears. But the book also describes the wave hitting salelite uplink dishes and thus part o f the energy being focussed on them. $\endgroup$ – Hennes Apr 18 '20 at 16:56

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