Only the space bar I'm afraid. Hold it to reverse the rotation of the firewall, release and it'll rotate the other way. There is a lot of inertia as others have noted. The firewall only burns red orbs.
The excessive particles can make some of my machines chug which makes it much harder to see interation. ZapJackson has a good suggestion that I need more visual feedback when you press space to make up for the intertia.
I'm collecting feedback for a post jam update - thanks everyone for their comments!