I'm showing my age here but I used to play Orbitron on the Commodore 64. I'd press Shift-Lock and fire automatically, you've turned that into a feature!
I always make a suggestion on everything I review, and for this game I think some sound would help. It may not be realistic in space but the sound of an exploding asteroid would be pretty satisfying.
You've used exactly two buttons to fit the theme perfectly and the ship is nicely responsive.