on reflection, a correction

It's not right. The visible light photons absorbed are higher-energy
and thus higher momentum than the IR photons being re-emitted as
waste heat. The waste heat IR photons are being re-emitted both from
the front and back. The panel is also absorbing IR and other
non-visible-light photons from the sun (a certain fraction of its
luminosity is IR); these are being re-emitted as well.

There's a net anti-sunward thrust, but probably just a fraction that
of a solar sail. How much depends on the properties of the solar
panels.

--- In spacesettlers@yahoogroups.com, Al Globus wrote: