Evolution of Titan׳s major atmospheric gases and cooling since accretion

At the lower Tac=300 K, thermal escape of gases alone allows their atmospheric masses to decrease from the primordial to the present-day levels in 50,000-70,000 years, when Titan׳s temperature has decreased to 245-255 K. Below this temperature, the NH3 atmospheric mass is comparable to the present-day N2 mass. Thermal escape does not contradict the existence of the photolytic sink of CH4 in the cooled Titan atmosphere. The thermal escape mechanism does not require arbitrary assumptions about the timing of the start and duration of the gas emissions from the interior.