Electric comet 67P

So we know there will be no visible lightning bolts, plasma arcs of huge sparks jumping between any body in the solar system because either they are already surrounded in conductive plasma or the gas pressure is too low to allow dielectric breakdown.

There is one further way for dielectric breakdown to occur in a high vacuum, that is through field emission.

( 16 pages )
[link to www.classe.cornell.edu]

Field emission is a mechanism whereby electrons can tunnel out of a material and cross a vacuum, given a high enough voltage. The voltage has a linear relationship to the gap distance and is related to the work function of the material. A typical value for a metal ( like Rosetta ) is 6E+7 V/cm, that is 60 million volts per centimetre. So now we can use this value to calculate the voltage needed to zap Rosetta from 67P, if it was possible for them to be at different potentials.

Today Rosetta is 9 days and 2223km from 67P.

So it would take 1.333E+16 V, that is
13.33 petavolts or
13,330,000,000,000,000 V

K