Expanding on the initial idea surely we could expand further.

So, we have explorer missions ( to explore sectors and find new systems to explore ) and then we have patrol missions ( known systems with known problem spots ).

Surely these could be combined somehow.

An unknown system is only unknown ( to the player ) until they discover it so they should be able to go there repeatedly if they so wish as they know where it is etc. To other players yet to go discover it, it would still be unknown until x days/weeks/months/years when the report is handed in by the original discoverer or multiple discoverers in which case surely it should then become part of the constant system.

You could balance this out with sudden planet/system upheavels involving rescue attempts prior to the system or planet being destroyed forever.

It may not be feasible now if the data system is unable to handle it but it would be something interesting to have included.