The fast atomic oxygen corona extent of Mars

The production of fast oxygen atoms in the Martian exosphere as a result of the electron dissociative recombination of ions is re‐evaluated for the time period appropriate to the Phobos 2 mission. Because of the prevalent condition of solar maximum activities in 1989, both the upper atmosphere and ionsphere should have more extended structures than those encountered during the Viking Orbiter (VO) mission in 1976 which was near solar minimum. We compare the distributions of the hot oxygen atoms for these different levels of solar activities and find that the number density of the hot oxygen atoms during the Phobos 2 mission should be a factor of two larger than estimated for the time period of the VO mission. The non‐thermal escape rate of the exospheric oxygen atoms is thus comparable to the ionospheric escape rate measured in the Martian magnetotail. Furthermore, the flux of the oxygen ions picked up in the hot atomic corona should be more intense than previously thought.