They had the same type of engine system, fusion generators powering high-thrust ion rockets, sitting at the base of a kilometer-long girder tower.

The small glow of the ion rocket would be invisible at the distance, surely.

How they moved that mass from Earth to Mars with only chemical and ion rockets, I'll never know.

A development of the ion rocket, it can make loops in the space-time continuum; travel time back to Earth, subjectively, is a matter of hours.

We might use ion rockets, solar sails, gravity assists-whatever.

There was a docking mount and an instrument module at one end of the core booster, and a cluster of ion rockets at the other.

Smaller ion rockets surrounding the main drive ring provided for maneuvering and docking.

The Herter-Halls were strapping ion rockets onto the object to nudge it out of orbit and back toward Earth.

Even an ion rocket contributes some vibration to a spaceship, and we were still a long way off.

The traditional spaceman's send-off; propelled forever into the Universe by a funerary ion rocket.