The discussion about low population worlds got me to wondering from an official TU sense (but also might turn into an IMTU question), what kind of sensor systems do main worlds have available when those main worlds are low population or low tech?



Reading through the T5 rules on sensors, it seems mostly oriented to ship to ship or ship to surface detection. I presume the same rules can be applied for surface to space detection, or a world could build a satellite packed with detection systems, but I haven't seen reference to how typical that is. 

Is it possible for Travellers to "sneak into" a system and land on a world undetected? I imagine that a TL0 pop 5 world would be blissfully unaware of the activities or even existence of starships throughout the system or even coming and going to points on the surface not immediately adjacent to a population center and given that Traveller ships don't (seem to) undergo meteoric reentry that further enhances the ignorance of the activity on a world like that. 

Or own TL8-ish Pop 9 world is just getting to the point that automated (optical telescope) survey is catching things like 1I/Oumuamua sailing through the system and lacks the capacity to image that as anything other than a point of light. It could have been imaged by goldstone radar if it were considerably closer, but it wasn't all that far away and radar imaging was not possible. 

So, in short, how aware are typical worlds of their near-space and deep system surroundings?