The episode postulates the melting of the Martian icecaps and creating a greenhouse effect, the eventually developing a breathable atmosphere. The flaw in this is that the core of mars is too cold. In order to hold onto an atmosphere, the planet would need a churning molten core. Unless the core is heated first, the atmosphere will be lost. Scientists believe that this is what happened to cause the loss of surface water on mars and most of its earlier atmosphere.