Recovery and Validation of Mars Ionospheric Electron Density Profiles from Viking Orbiter Radio Occultation Observations

The Viking Orbiter radio occultation experiment acquired vertical profiles of electron density in the ionosphere of Mars. As these profiles were not archived, they were thought to have been lost. Here, we report the recovery and validation of the complete set of high-quality, dayside electron density profiles from Viking Orbiters 1 and 2. Sixty-nine profiles spanning solar zenith angles of 50 degrees-95 degrees were deemed acceptable for scientific analysis. Relative to the widely used set of radio occultation electron density profiles from Mars Global Surveyor, these Viking profiles have better sensitivity, higher vertical extent, more global coverage, and greater solar zenith angle coverage. They are ready for use in scientific investigations of the ionosphere of Mars and related topics. They accompany this article as supplemental information.