Re: Can a argon lasar and a parabolic dish propell a ship through space?

Chris,

Yes, a laser can be used for propulsion. The type of research you recently 
saw was probably a concept demonstration by a researcher working with NASA 
Langley Resarch Center. The craft is a mirrored saucer with a parabolic 
torus base that focuses a pulsed laser just below the vehicle. The air 
under the vehicle then expande exploseively and pushes the craft upwards.

This type of operation will only work up to about ten kilometers 
(six and a half miles): after that point, the vehicle has to provide gas 
from onboard tanks.

Nasa also has a variation on the idea for non-atmospheric operation where a 
large mass of frozen water or carbon dioxide is fixed to the bottom of a 
similar craft, and laser pulses vaporize the material and heat the gas to 
make it expand.

The NASA laser propulsion page is at  http://www1.msfc.nasa.gov/STD/propulsion/research/laser/index.html#here

This page currently has some problems, but it does have functional links to 
 further information about this project.

I hope this is helpful.