by sklar
Omega2064 suggestion (landing zone counters) is a good way to go.When I drew Europa, I originally made a version with landing zone markers, which you can find here.
I also made a copy of Mars with the same landing zone markers, which you can find here. You might notice that this Mars is a bit different; it is. I erased 3 or 4 Neutral zones, because I felt the board was too open and could use some choke points.
I've never played with Pluto or Titan, so I can't help you there, and made simple landing zone counters when I used Io.
Hope this helps!