The term Astro in this case means a star or stars. Fornication, of course, means to have sex with, or to fuck. An Astrofornicator is a Starfucker, in base terms. Incorperated, of course. Starfuckers, Inc.
Man, astrofornication sounds like something the chili peppers would come up with! I wouldn't mind flying out to the sun and commencing some lovin on it, personnally