About: As a project, I'm trying to solve for the approximate radius and mass of a approximately earth-sized planet, Mann, from Interstellar. According to what was provided, g = 7.84m/s2 The solid part of the planet is composed of a honeycomb of rock and ice The space inside the honeycomb is filled with largely ammonia, about 20% oxygen, gaseous chlorine (can support human breathing for a short amount of time) and possibly carbon dioxide The "surface" temperature is between 0 and -33 celsiusFrom research, I have found a moon with compositions similar to Mann: Ganymede. On Ganymede, g = 1.42n/s2 The planet is composed of 50% rock and 50% ice The planet has oxygen in its atmosphere, although it's probably too insignificant to countProblem: I do not know how to find the mass and radius of a planet, given its density and gravitational pull. Can gravitational pull and radius increase without changing the density? Is it better to consider Mann a bigger version of Ganymede or a small, frozen gas giant? PS more information on Ganymede is available on Wikipedia; Dr Mann talked about presence of hydrocarbons (thus carbon dioxide) as a trap; however, there was no proof that carbon did not exist on this planet.