I can appreciate wanting to make it a bit more random for success for planet invasion

however it doesn't seem to make any sense to me how you can fail when attempting to invade a planet with ZERO defenses, player not in a legion, player not guarding a planet and a heavily armed ship is doing the invasion.

very annoying to be told you only had 90% success rate in that scenario and still fail on the invasion

+1
Dan at some point it should be 100 or 99%.
and if you fail the game should say in a case like this that your ship failed go repair X equipment and try again.

As I have suggested before, make invasions with normal attack capped at 90% but make invasion attack count up to 99%

You forget the Asterix option.

Fall on a planet populate with superhero guy, kick ass at your heavy armed marines.