Hey, this is a neat little concept! I hopped right into the game without reading the game page and for probably 3-ish minutes, I went around hitting buttons to find out most of them didn't do anything (at least, I couldn't tell if they did anything). I also didn't understand my goal or what I was supposed to be doing at first, which made the experience confusing for me.
After reading the game page and understanding my goal, I revisited the turret. In my first visit before reading the game page, I took control, fired a few times, and just kinda left it because I assumed it was just there for fun. After reading the game page, I started actually trying to aim at asteroids, but didn't see the aiming reticle for the cannon this time. I stopped controlling it, started controlling it again, and now I saw it. I noticed the bullets that got fired off didn't line up very close to where the reticle showed me aiming and I believe this is a bug. I also discovered shortly after that, that the cannon goes off of my crosshair instead of the giant in-game reticle for destroying asteroids.
My play time in this game was spent mostly being confused before reading the game page. That being said, I think this is a fun concept that could be really fun with an in-game tutorial that teaches you the game and shows you your goal. I also think more consistency with game mechanics like destroying asteroids would make the experience more enjoyable as well. I think this is a good proof of concept to get started on further development, if you choose to do so :)