On Fri, 25 Sep 2009 11:01:11 -0400, Wayne.B
wrote:

On Fri, 25 Sep 2009 08:08:57 -0400, Tom Francis - SWSports
wrote:

He estimated that a single sail, six miles across, could
boost an object the size of our moon out of orbit and complete one
grav of acceleration in ten years.

Not to be argumentative, but since the moon already has a surface area
far larger than 6 miles across, why isn't it being boosted out of
orbit as we speak ?

Heh - I know, counter-intuitive, but the answer is orbital mechanics.
I don't have the exact math on it, but the moon, planets - almost
everything is affected by photon radiation - you're right on the
score.

But the glue that holds it all together is gravity, momentum, etc.,
and it doesn't take much to upset the apple cart - that was the point
of the exercise.