[dzhiurgis]

The fact we speak about it already sometimes suggests it has been already deployed, sometimes for many decades.

Can it (a SAR sat doing a flyover) somehow be detected from ground?

[ACCount37]

Yes, as long as it's active. Like with any other active radar - you can detect the radio waves and narrow down on their source.

[dzhiurgis]

Are there any stations that track this? I wonder at which point we'll become 24/7 SAR surveilled.