Atmospheric Escape Explains Diverse Surface Compositions of Pluto vs Sedna

Kuiper Belt Objects are thought to be remnants of early solar system materials, which have retained volatiles such as 〖CH〗_4 and C_2 H_6. Spectroscopic data from various sources reveals that while Pluto retains 〖CH〗_4and C_2 H_6, Sedna shows a lack of 〖CH〗_4 but an abundance of C_2 H_6, (Emery et. al 2024). We hypothesized that 〖CH〗_4, which is stable on Pluto, is able to escape from less massive Sedna. Sufficiently rapidly to be depleted over the age of the solar system while C_2 H_6 has been retained due to its larger molecular mass. Utilizing models for Jeans escape and hydrodynamic escape, as appropriate for a given mass of object and of escaping species, we analyzed the stability and escape rates of 〖CH〗_4 and C_2 H_6 on both Pluto and Sedna. We explored a wide range of masses of Sedna, ranging from ½ to ⅒ the mass of Pluto. We also tested three different abundances of 〖CH〗_4 and C_2 H_6 using measured values from Comet 67-P, and Enceladus, and an upper limit assuming clathrate hydrate. We tested these abundances for two different outgassing rates from the interior, 10% and 100%. We find that 〖CH〗_4 remains stable on Pluto, but escapes from Sedna due to its lower mass, whereas C_2 H_6 remains stable when using both 100% and 10% outgassing rates. This result is in agreement with the observed spectra and leads to tighter mass constraints for Sedna. Our model also explains the observed absence of methane on another KBO, Gonggong.