My first game I got 3 missions to scan ships way off in the corner of the map (70, 70k, and 90k) and immediately set off to find them, despite only having the fuel for a one way trip. It worked out incredibly - I picked up some extra salvaged ships along the way and came back over 230k credits richer with a full hold of AI cores and supplies and guns and everything. And I only visited the 3 systems for the missions, I didn't go looking for more.
The thing is, the first system I came to I was almost out of fuel. In there I found more than enough to reach the 2nd, and the 2nd nearly topped me off, and the 3rd I had more than I could carry. And they weren't particularly close together. Right now, you can fly out to the edge of space with just enough fuel and supplies to get there and can count on finding more than enough to not only keep exploring, but get you home with full tanks and cargo holds.
What if we removed fuel from old dormant ships and such? You could still get some fuel by fighting the active ships (pirates, roaming neutrals, or the spoiler faction out there) but wouldn't be able to count on finding plenty of fuel at every ancient survey probe. The lore could be explained as the fuel on these old ships isn't good anymore or just isn't compatible with newer ships. You could reduce the drop on supplies a bit too and replace it with stuff like rare metals and goods and such.
This would mean you would have to bring a tanker and carry enough fuel to get there and back again for every mission, and carry some extra supplies out too. Returning would be with a full hold of valuable goods instead of a huge load of fuel and supplies, and each trip would have a point at which you have to return for more fuel/supplies instead of just going till you have full cargo holds.
