May I suggest a simplication? From a sufficient distance planets and their moons (such as Jools) might be represented as a point mass of their total. The location of the center of mass would be dependent on the position of the moons at the time. This would reduce the number of Ns. If the planets and moons remain on rails, the gravity they exert on each other does not need to be calculated. The gravity exerted by ship parts is probably too small to need calculating. Would the gravity exerted by comets also be calculated? Is there a plan to select the detail / accuracy of the calculations to reduce processor load?
