If you would be interested in proving what the force of gravity consists of, you might go to
http://timebones.blogspot.com and there you will find how to perfrom an experiment on how to form and collapse a gravitational field. c2=e/m.
Your assumption that the planet mars has no heat energy is obviously incorrect. You will note that the shape of planets is that of a sphere. This is also true of our sun. The reason for this shape is that the heat energy within. This process is used in making shot for shotgun shells. Heat energy within a mass forms the mass into a sphere, if the temp is great enough to break the electron bonding. The reason asteroids are not spherical is that they do not have adequate internal energy to form them into that shape.