Planetary Planning
Fortunately, you have a model that is capable of calculating the fuel storage requirements, as long as you know the average distance between points on the surface of the planet.
Additionally, the model does not require the Geodesic distance (i.e. the distance betwen poles would be the diameter, and not the length of the arc).
You can assume that the planet is a perfect sphere. What is the distance between two points on the planet?
Note: for simplicity, use the radius of the planet as the distance unit.