Excerpt

"Thirty hours out of Mars for Terra, the Solar Queen sped along her silent, invisible course. No longer was she completely severed from all connection with the planets of the inner system; the trick cams that controlled the beams at Venus Equilateral kept the ship centered by sheer mathematics. It was a poor communications system, however, since it was but a one-way job. Any message-answering would have to be done thirty hours later when the ship made planetfall, and the regular terminal office of Interplanetary Communications could be employed.

In spite of her thirty hours at 2-G, which brought her velocity to eleven hundred miles per second, the beam-director cams did their job well enough. It was only in extreme cases of course-changing to dodge meteors that the beams lost the ship; since the cams were not clairvoyant, there was no way to know when the autopilot juggled the controls to miss a bit of cosmic dust. The cams continued to spear the space through which the ship was supposed to pass according to the course constants."