Thank you for the nice comments and the feedback!
The tactic you're describing is definitely something that was on our radar as we were developing the game. Our earlier build had the asteroids be sold entirely, but the feedback we got was that it was really jarring to have massive asteroids just pop out of existence; having them be broken up into tiny chunks which get ground up one by one felt a lot more satisfying.
Ultimately we decided on the current system, because whilst it might enable some cheesy tactics, those were still a lot more fun to discover and master. In a more fleshed out version of the game, we'd definitely try to address the issue in a way that still keeps the grinding effect.