Sol88 quoted Wal Thornhill
No mention of jets or how EDM machining produces them.
Jets cannot be produced from EDM machining of "high points" on comets. The heating of the surface to machine it will cause material to escape in all directions. So there will be fans not jets. This will happen even if the "high point" is a flat surface.
To get jets in the real universe the EDM would have to happen at the bottom of pits or craters. By definition the walls of pits and craters are higher than their bottoms. The EDM will always happen at the "higher point". Therefore no jets.