Collision Orbit, published in the July 1942 issue of Astounding, begins in early 2191 on the sleepy colonized asteroid Obania, which is suddenly endangered by a smaller asteroid after a random collision with a seetee body alters its orbit. "Spatial engineer" Jim Drake, tugboat pilot Rob McGee, and young heiress Ann O'Banion try to divert the asteroid - which they name Freedonia - which would enable them to claim it in recompense and use it as a laboratory for Drake's seetee experimentation. The attempt to install a paragravity engine at the center of Freedonia fails due to bad luck and economic sabotage by Mandate authorities, but in the end Drake succeeds by steering a mass of anti-iron into a borehole, where the resultant matter-antimatter reaction can function as an improvised rocket. The Mandate reluctantly recognizes Drake's claim, and his son Rick - inspired by his father's success and angered by the Mandate's unfairness - joins the family business.
