Shields for the starship enterprise

A renewed interest in human space exploration demands renewed care for the safety of astronauts venturing far from Earth's protective magnetosphere. Here we assess possible mechanisms for the active shielding of a spacecraft, with consideration of scale, effectiveness and power use. Although nothing yet exists to match the apparent simplicity and effectiveness of the shields shown on Star Trek, the physics of plasmas demonstrates that some useful form of shielding should be possible in the next few decades