[ale] [OT] grounding in space

[Phil Turmel]

On 08/28/2017 01:50 PM, Jim Kinney wrote:
> The (bs) EMP bags made me think (usually a good thing!) about circuit
> design (a field I'm not good in).
> 
> For a spacecraft, the obvious choice for ground plane is the craft
> framework itself. Relative to the typical power loads in the various
> modules on ISS, the frame is a "near infinite supply or sink of
> electrons".
> 
> But space weather is nasty. Solar flares are huge problems. How is a
> system designed to withstand an EM flux greater than the typical power
> throughput? On the ground, we use fat braided copper wires and deeply
> buried rods. That's not an option on a satellite. Thick skin can
> shield. What else?

You don't shield everything.  You shield the ICs with as small a shell
as possible, and every other circuit in the whole spacecraft is a
precision engineered tightly twisted pair w/ carefully balanced current
flows.  Both power and signal.  Plus optical isolation between any
devices grounded to different parts of the structure.