William Elliot wrote in message ...
However the effectiveness for magnobraking at Mercury seems dubious
because of the weakness of it's field. It's usefulness for electricity
next to nil with such an abundance of solar energy there. Yet with the
need of four flybys to attain Mercury capture of the MESSENGER mission,
could the assistance of less than one thousandth of Earth's magnetic drag
be of use for final orbital trimming?

Yes, it's not a big enough effect to bother building into a craft.

On the other hand, the thrust from a light sail goes up as the inverse
square of the distance from the sun so a light sail equipped craft should
be able to navigate into orbit around Mercury though it would take it quite a
while to build up enough speed to slingshot around the moon and escape
Earth orbit.

Also if you are going to operate near Mercury, consider that the Sun has a
magnetic field about 100 times stronger than Earth's.

-HJC