Potential Bug - When you harvest one asteroid, all asteroids become unharvestable for the cooldown
Good catch — right now there's a single shared gather cooldown, so harvesting one asteroid locks them all, which definitely reads like a bug.
I'm reworking it so each asteroid harvests on its own cooldown (so you can work several at once), and bigger asteroids will yield more but take longer to recharge.
Thanks for the sharp eye — patch coming.