Space Traffic Control: intercepting signals in space

[GTOM]

Otherwise, do i know right, that laser (or well directed radio) signals in space can't be detected unless a probe gets between the emitter and receiver?
So i can write, that a captain can calmly negotiate about backstabbing his ally?

 

[mfb]

Otherwise, do i know right, that laser (or well directed radio) signals in space can't be detected unless a probe gets between the emitter and receiver?

Right.

 

[GTOM]

Although i still wonder. Due to limited telescope accuracy, from big distance, even a long boost phase appears to be a single point.
And after thrusters stop and ship cools down, IR emission drops by many magnitudes.
Could they determine, where exactly the ships are going?

 

[mfb]

Spectroscopy from different directions could give 3D velocity data. Tracking the exhaust direction, if possible, can help as well.