i'm not Elite in exploration either, but i see similar missions at my home base and the target destination always seems to be ridiculously close, i.e at the furthermost outpost in the very next system, just like in all the other missions.
for what it's worth, i'd like to see something like (hypothetical examples)
"Commander, we've just had an urgent request from the scientific outpost in HIP 52137. A crewman has fallen ill and needs some of our unique vaccines delivered immediately. HIP 52137 is (280Ly) from here and our ships just don't have long enough legs to make it there in time - if he doesn't receive treatment within (0h 42m) then we might not be able to save him. Commander, we really need your help!"
or...
"Commander, if you've been following GalNet lately you'll know that the serial murderer Festus Zeck managed to elude authorities and escape to an outer core system. A sympathiser of his has deleted any entries for that system from Universal Cartographics' database**, but what we do know is that he's on a station called (Cameron Hub) and it lies in a system within (25Ly) of (HIP 52137). Find (Cameron Hub) for us, Commander. Simply dock there and contact us via their bulletin board - we'll instantly triangulate your position and that will be our cue to send in a team to recapture him."
...the point being, missions involving longer distances, or locating 'X' within a given radius and within a certain timeframe would be a bit more explorer-worthy than simply 'go to the next system along'
**pick any populated system that does not initally have exploration data. there's plenty of such systems.