[X] My Assistant

[Phil Stooke]

Explorer 1 said:

"A 2D map of C-G seems like a tough order; the projection math alone..."


Don't worry! If you can put a grid on the surface (as we have seen already), you can warp that grid into any map projection you like. Mapping will be no huge problem - in fact I expect they have a rough one already (I've been playing with one myself).

Phil

[ngunn]

slighter lower energy to depart from the comet at the midpoint

You made that statement before, but the opposite is in fact the case. The midpoint is the place on the comet's surface where gravitational potential is lowest, therefore material there requires more energy to escape than surface materials at other locations. Escape velocity depends only on the potential at a given point, not on the local value of the field strength. Saltating material (stuff that doesn't depart) would tend to migrate toward the neck, not away from it. The neck should act as a dust trap whilst the comet is far from the Sun and relatively inactive.

Once activity starts, however, my guess is that the ejection processes easily overcome the comet's weak gravity - irrespective of position on the comet. There are all sorts of possible reasons why the neck might be an active location - different material, looser packing, differences in insolation (was it a cold trap for volatiles at some point?), release of gravitational energy due to mutual settling of the two lobes, etc. etc.

[Y Bar Ranch]

You made that statement before, but the opposite is in fact the case. The midpoint is the place on the comet's surface where gravitational potential is lowest...

If you were to take two spherical objects and connect them with a stick (or have them orbit each other) then the low potential point would not be at the midpoint between them, I.e., at the center of mass of the two body system. There would be two low points, at the center of mass of each of the two spheres. The midpoint of the system is a saddle point, with a higher potential than either of the two centers.