Orbiter?

How does one use the orbiter? It keeps hitting me, and it made me have a game of -99!

space releases it, Ctrl repels it
if the orbiter runs into an object, it destroys the object.
you don't need to use it though, it's easier not to

The only other thing anyone can tell you is that practice makes perfect. Experiment with it and see what works best for you, whether to use it or not, and if you use it, how you work around it so it doesn't hit you, but hits your enemies instead.

i usually activate it after the rocks start appearing for the first time

If that works for you, then that is good. I usually don't use it at all, it just seems to get in the way more than it helps.