Be quantitative where possible. Use the grey approximation. Derive an expression for temperature as a function of distance. Assume that the matter starts out at rest at infinity, and ends up in circular orbits, and that the energy difference between the two is all converted to thermal energy. Neglect any other energy sources or losses.
Gravity is double Earth's.
CO 2 clouds may have formed in Mar's atmosphere. Make sure you can convert from atmospheric pressure to total atmospheric mass easily. The optical depth equivalent to SPF30 is about 3.5.