Photonic Laser Thrusters

[Prius]

http://www.photonics.com/content/news/2007/February/22/86585.aspx

I found this a while ago and thought it was pretty cool. I'm wondering why there wasn't a big deal made about this. It's revolutionary! Why didn't anyone talk about this? Or am I being stupid and miss some big drawback?

 

[Scarecrow]

http://www.photonics.com/content/news/2007/February/22/86585.aspx

I found this a while ago and thought it was pretty cool. I'm wondering why there wasn't a big deal made about this. It's revolutionary! Why didn't anyone talk about this? Or am I being stupid and miss some big drawback?

I'm not an expert, but I've heard that the drawback to photon thrusters is that 1 newton of force requires 300 MW of power. Also, bouncing photons back and forth between two spacecraft would require that you want to accelerate two ships in opposite directions, and it would only work over pretty short distances, so no missions to pluto with this. And the mirrors would need an incredibly high reflectivity to make the "many thousands of times" thing work. 0.99 ^ 1000 = .0000432, meaning that there's very little benefit once you get anywhere near this many bounces.