Heyo, gave the game quick run, and I see a game like this having potential. I'd definitely recommend adding more to tone down the repetitive nature of the game(maybe power ups, or some other attacks). Mix up the enemies; perhaps have one that circles the planet before colliding.
Personal preference, but it'd probably feel a bit better if you were to smoothly rotate the player around the planet as opposed to it being static.
Also; I'm not sure if it does already, but the larger asteroids should deal more damage than the smaller ones. helps put priority on them and makes it more interesting to make decisions.
Just some thoughts and ideas I had when playing the game; take em with a grain of salt. Hope the best for your development!