No, it does not work for asteroids. For some reason, the powers that work for storms don't work the same for asteroids. Sight obscuration doesn't work at all.
This is really annoying because the absolutely classic, cannon SciFi way for a smaller force to escape from a superior force is to duck into an asteroid belt.
I'd like MM to change that so it can work, and to make it possible to put more than one ability on one object. What if I'd like ALL storms to have sight obscuration, and then some of them to also have other abilities? As far as I know that cannot be done right now.