[euroderf]

Thinking about this, and about the big launchers that the three-letter agencies use...

I wonder if US satellites (a) use a lot of Kevlar (or similar), and (b) can see nearby explosions (like, the triggering of a fragmentation weapon) and quickly close semi-armored shutters over their vital bits.

One would defeat this by creating - out of detection range - a fragment cloud that is on an intercept course. But that might be too complex and time-consuming if a war is starting. So what is the threshold for plausible deniability ?

And of course there's also railguns, à la The Expanse.

[wkat4242]

No. Satellites don't use armouring at all. It makes the launch way too expensive. And there's always exposed bits that can't be armoured like solar panels and antennas.

What they do use is... foil! There's a thin layer of foil a bit away of the main body. If a small piece of dust hits it at crazy speed, the impact with the foil will make it (and a bit of the foil) vapourise, and then it won't cause much damage to the main body because it's all vapour.

It's not really like the expanse because a railgun fires tungsen rounds that are meant to penetrate. Most random space crap is just flecks of paint, drops of oil etc.

[euroderf]

I get your point about the utility and appropriateness of foil.

But then what about warfighting ? I'll betcha the US has a railgun up there somewhere.