http://www.orbitalvector.com/Deep%20...rentz%20Microp
robes/LORENTZ%20MICROPROBES.htm

I saw this yesterday on Disovery Science and hadn't heard of it
previously. The goal would be to use charged nanobots which would be
accelerated by Jupiter's magnetic field (Lorentz force) to great speed.
The charge would then be turned off after which they'd shoot away into
space. The guy who invented it said that with current technology we
could get up to a couple of percent of lightspeed and up to lightspeed
in the future.

Maybe NASA should give this a try, just to see if it's workable.