I quite liked the game a lot. Music is good, and the effects have great impact.
The upgrading ship was quite a good hook to put some urgency on the side of the player. I do think that the ship starts out to strong, as almost the instance you place an asteroid it gets shot down. This pushes the player to grind for upgrades, which puts the awkward nature of the two buttons to the front spot. I don't see a good reason to have to click to queue up an asteroid. It's technically a reaction challenge, but it leads to the obvious strategy of spamming the queue key. It's not that interesting, so I would just have the queue trigger automatically. Then you also don't need to both press the shoot button and click on the screen to launch an asteroid.
Also, I eventually won because the ship failed its targeting, which was surprising. I have no idea how I did it, but it kept happening every so often, eventually destroying the ship. That was unfortunately a bit anticlimactic.
A suggestion, right now there seems to be no reason to not shoot from right up the red circle. Maybe you can have further boulders built up speed, such that they go faster when they do eventually reach the red circle.