[dsr_]

Referenced: cost of firing a laser is $1 of gasoline run through a generator. That's roughly a liter.

Let's say raw energy content is 32MJ/L, and we have gasoline=>electricity losses of 50% and laser efficiency of 30%, so we expect a little more than 5MJ per shot.

If you can hit a 2m target moving at 5Km/s through 1000Km of space and atmosphere with 5MJ, how much energy can you put on a 1m target moving at 7m/s at a range of 500Km?

The difficulty in killing people from space will be targeting, and the limited availability of fuel and oxidator in space.

[AstralStorm]

Even more so, limited availability of cooling. Overheated laser melts rather than firing, so it will likely need active cooling droplet heatsink for fast refire in case it does miss or enemy fires more than one missile, and that's a limited resource.

[pdonis]

So basically the system from the movie Real Genius?

[ShadowBanThis01]

Exactly what I think of, every time.

Now off to make some popcorn...

[arijun]

> limited availability of fuel and oxidator in space

And don’t forget—-you have to fly up Tory Bruno each time to fire it.

But as a platform for assassination, it doesn’t seem so far fetched. The two main things I can think of that would make it difficult would be the much higher attenuation and scattering from the atmosphere, and the need for a different (telescope based?) target acquisition method.

[jjtheblunt]

would the atmosphere along the beam path vaporize in short order at those power levels, so scattering/attenuation is temporary for a fixed beam?

[nine_k]

If it does so, the resulting plasma will very actively absorb the laser pulse's energy.

Your best bet is not interacting with the atmosphere in any way, and merely adjusting for refraction.

[akiselev]

Maybe, maybe not; self focusing [1] is an active area of research. Optics is one area where secret projects have been shown to be way ahead of what is publicly available [2] so I wouldn't be surprised if they've figured out some scifi way of making orbital lasers more effective.

[1] https://en.wikipedia.org/wiki/Self-focusing

[2] https://en.wikipedia.org/wiki/2012_National_Reconnaissance_O...

[ikekkdcjkfke]

What about a huge sun lens in space to concentrate the sun rays