Tomographic Radio Occultation Methods Applied to a Dense Cubesat Formation in Low Mars Orbit

The atmospheric measurements made by the eight Mars orbiters in operation (as of April 2021) significantly improved our understanding of the Martian weather and climate. However, while some of the existing Mars orbiters will reach their lifetime, innovative and cost-effective observation concepts are requested - not only to guarantee continued observation but also to address potential gaps in the existing observing network. Inspired by the success of the two MarsCube One satellites we have established an observation concept, which is based on a series of cubesats, carried to Mars and injected into a low Mars orbit in a so-called string-of-pearls formation. Over the lifetime of the cubesats of about one Martian year, a series of radio occultation (RO) experiments will be carried out with up to 180 partially overlapping RO measurements per day. For processing of the unique set of observations, tomographic principles are applied to the RO measurements for the reconstruction of high-resolution two-dimensional temperature and pressure fields of the lower Martian atmosphere. Unlike the standard Abel transform approach, the derived products are not dependent on spherical symmetry assumptions. Thus, insights into various unresolved atmospheric phenomena are obtained - especially of those which are characterized by distinct horizontal gradients in pressure and temperature, for example, as observed at the day-night terminator, during dust storms, or over complex terrain.