-The only signal that can go through space are lightwaves due to the fact they produce their own medium to move thanks to their electromagnetic field.
Actually just about anything can be sent through space. For example, carrier pigeons can be thrown from the moon and hit a base on Neptune if you wanted.
Really all forms of radiation tends to work just fine, mass-less or not, so for example you can still see a human's bioluminescence, or use a thermometer to track heat, or put water in a glass chamber full of wires as a crude gravity sensor. Through Darkvision allows you to see even in a true vacuum at absolute zero, ie no stray photons or even atomic movement, but whatevs.
What part of "space vacuum is good enough so that planets/comets/stars keep stable orbits for millions of years" didn't you understand?
I'm not astrophysicist but I'm pretty sure it is balance of gravitational forces and momentum. Like satellites are technically in a state of constantly falling at a controlled rate, they simultaneously chase after Earth's gravitational field as it hurls around Sol while centripetal forces generated by spinning around the Earth's gravitational field are held as close to a near match. That sound about right? I think it is.
Either way I would like to be there a reason for players to pick electronic sensors once in a blue moon (aka fighting in space instead of land/atmosphere/water), otherwise it's "screw radars, I have imbasight trollolol" time all the time.
Blue moon?
Throwing an Elf into a Pilot's seat gives him a 60mu range but imposes up to a -6 penalty to Spot Checks to do so and it's still subject to illusions & fog. Spend one Hardpoint and you can flawlessly detect anyone in 60mu off the lowest Arsenal upgrade and you get a sweet +1 to damage rolls too. Heck by the second level of Arsenal you start ignoring walls too, I'd think it's pretty hard to have a hidden asteroid base if the doorway pings everyone's scanners once they are within 120mu or less.
Point being, the upgrades are strictly better than what D&D offers anyway.
Of course someone is going to want them.