Dear Chandra: In my student days I would not have had to ask you this question. But I have not enough time to relearn orbit mathematics even though I have “scanned” this : http://en.wikipedia.org/wiki/Orbit
I am thinking about the force exerted on a orbiting comet as it approaches its perihelion. I assume the force is maximum at the perihelion.
As 67P’s perihelion is further out from earth (between earth and mars) I was wondering what the “pressure” really was on the comet? Are you sure this is what is causing the geysers to increase? Somewhere you wrote/implied that the geyser-causing pressure might be nuclear?