In sci.space.policy John Ordover wrote:
Someone correct me if I'm wrong, but in general an analogy to solar
sailing would be to move a terrestrial sailboat by hitting the sail
with a whole lot of high-speed ping-pong balls.

Light is massless but not energy-less, natch, so it winds up having a
similar effect on objects to the ping-pong balls. Just as some of the
momementum of the ping-pong balls would be transfered to the sails,
some of the energy of the light is transfered to the sail. Just as
the ping-pong balls would therefore lose some energy, the photons in
the light lose some energy, but light does that all the time.

So what's the problem?

There isn't one.

--
Sander

+++ Out of cheese error +++