Nah - a cube is tiny compared to a planet and though it's self-healing the Enterprise demonstrated in "Q Who" that it could be damaged. It's not that big. Faced with even the fleet of Kirk's time - twelve ships that could each destroy the surface of a planet - it wouldn't last long enough to automatically repair itself. The only way it survives is if it's from Krypton and gains invulnerability from Earth's Sun.
I can't believe I'm having a nerd moment here. I must go to bed.