NASA is examining beamed energy propulsion for space launches.

http://www.space.com/10658-laser-rocket-propulsion-technology.html

Laser Propulsion Could Beam Rockets into Space
Prachi Patel, Astrobiology Magazine
Date: 21 January 2011

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NASA is now conducting a study to examine the possibility of using beamed energy propulsion for space launches. The study is expected to conclude by March 2011.

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Thermal propulsion vehicles would be safer than chemical rockets since they can't explode and don't drop off pieces as they fly. They are also smaller and lighter because most of the complexity is on the ground, which makes them easier and cheaper to launch.

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Parkin developed the idea of microwave thermal propulsion in 2001 and described a laboratory prototype in his 2006 Ph.D. thesis. A practical real-world system should be possible to build now because microwave sources called gyrotrons have transformed in the last five decades, he says. One megawatt devices are now on the market for about a million U.S. dollars.

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Sending a spacecraft to a moon of Jupiter, for instance, would require a laser that gives billions of watts of power. "You'd have to have another couple generations of space-based telescopes to do something like that," Kare says. "You can in fact launch an interstellar probe that way but now you're talking about lasers that might be hundreds of billions of Watts of power." Laser technology could reach those levels in another 50 years, he says.