Comments on: World’s 1st Space Sail ready

By: Reader's Write

Reader's Write — Wed, 29 Jun 2005 22:04:40 +0000

Sorry, conservation of momentum precludes this possibility.
If you fire a laser at the sail, the laser will receive the same impulse in the opposite direction as the sail. So unless you are running it from a point not attached to the actual ship (such as Earth, which is impossible to do at great distances due to the finite dispersion of the laser beam) it wont do any work.
Trust me I know what I’m talking about when it comes to physics.

By: Reader's Write

Reader's Write — Thu, 23 Jun 2005 08:47:20 +0000

I think the idea is to fire lasers at the sail to pick up the slack as solar energy diminishes - at least, that’s the idea …

By: Reader's Write

Reader's Write — Wed, 22 Jun 2005 03:13:54 +0000

Nice idea.
Unfortunately the number of photons on the sail goes as the square of its distance from the Sun. So the thrust is going quickly drop to zero.
Perhaps it’s OK for trips to the terrestrial planets but nothing more.