~100 mil maybe? i had just bought a "traveling around" stealth ship and upgraded 3 components to lvl15 when about 2 pieces of debris later i hit the big one.
i don't know why ship destroying debris is even in the game...the risk is so great that after having 2 ships destroyed in previous games, i've totally ignored debris until it was "turned off" this game.
i'll keep testing debris to see if it appears to be disabled or not.