A new era for space propulsion? An ion engine twenty-five times more powerful than NASA's current best model has just been ...

A prototype ion engine that uses lithium vapor as a propellant has aced its first tests, achieving 25 times more power than previous ion engines.

In the context of this conversation we're talking about thermonuclear explosions in space for power generation, not propulsion. So it being heavy is fine. Orion was meant to be propulsive so that ...

In 2028, if all goes well, NASA plans to test a new technology that could reduce trip times to the Red Planet.