Nuclear in LOW earth orbit

An article describing the US test in 1962

https://www.thespacereview.com/article/4822/1

Some suggestions on R&D to mitigate a threat:

https://warontherocks.com/2022/09/getting-serious-about-the-threat-of-high-altitude-nuclear-detonations/

Credit: U.S. Government/Public domain

A recent study, written after my research was concluded, is also interesting.

The Effects of High-Altitude Nuclear Explosions on Non-Military Satellites

Summary of a 400-Kilometer Altitude High-Altitude Nuclear Explosion The detonation of a nuclear weapon at 400 km altitude will damage or destroy a significant number of satellites, depending on the location of the detonation. The effects arise from both prompt radiation and delayed effects from weapon debris called the Argus effect. Neither will significantly affect satellites as distant as GEO. Prompt radiation will damage the largest number of satellites through X-rays. Earth will shadow most LEO satellites from direct line of sight. A 15-kiloton detonation will place roughly 4 percent of LEO band (160 to 2,000 km) of satellites at risk from prompt radiation. Any detonation of about 110 kilotons or greater will place roughly 20 percent of LEO band of satellites at risk from prompt radiation, which is all those in LEO within line of sight. Higher yields will expose this same volume to greater X-ray fluences. Greater fractions of the LEO band of satellites cannot be affected by prompt effects because of the shadowing of Earth (Figure 2). Although satellites can be shielded to some degree from X-rays, subject to weight and cost constraints, they cannot practically be shielded from gamma rays or neutrons. Any satellite within a distance that places it at risk to gamma rays or neutrons will be destroyed, but this zone is only kilometers to tens of kilometers from the burst point, depending on weapon yield. Although prompt effects are confined to a local zone around the HANE, the Argus effect is global. Within hours of detonation, electrons circle Earth in a band of L-shells. Any satellites whose orbits cross those L-shells and that are not adequately hardened will have their lifespans greatly shortened. Depending on burst location and yield, these electrons can remain trapped for weeks to years. Without detailed calculations, it is not possible to estimate how many satellites are at risk. It is certain that some fraction of satellites would be significantly damaged or destroyed. It is also possible that—depending on weapon yield and position of burst—a single detonation might not be sufficient to populate enough L-shells with enough electrons to damage or destroy all LEO satellites. Some EMP will be generated, but the EMP would only place at risk systems on the ground that support or use the satellites’ services. Some communications to and from the satellites will be diminished or obstructed completely over local areas for minutes to potentially hours. This assessment is for satellites of nominal hardening and does not apply to military satellites that may have significant hardening. The assessment is also for the detonation of a single weapon. The detonation of multiple weapons at different times and locations can have compounding affects that are greater than the sum of individual detonations. Also, if a significant number of satellites are damaged to the extent that command and control of station-keeping is lost, the risk of conjunctions (collisions) will increase.

Read the complete study here:

https://www.rand.org/pubs/research_reports/RRA3028-3.html