Mission Design Concept for in Situ Characterization of Saturnian Atmospheric Composition

An innovative New Frontiers class mission concept, designed to measure essential elemental abundances in the Saturnian atmosphere, has been developed as part of the 2006 NASA JPL Planetary Science Summer School and shall be described in herein. To date no in situ measurements of such properties at Saturn have been performed. Characterizing the heavy ion abundance (mass > 4He) and dynamical processes outer planets is vital to understanding the origin and evolution of the Solar System and, consequentially, extra-solar systems (Atreya, S. 2006). Consequently since water was presumably the primary carrier of heavy elements to the outer planets, quantifying the O/H ratio is critical to determining the enrichment factor of the gas giants' composition with respect to solar values. Elemental abundance information, including water content, will be available for Jupiter following completion of the Juno spacecraft primary mission in 2017 however comparable data for Saturn are not, and cannot be provided by the Cassini mission. Water, and therefore O/H, abundance may only be accurately ascertained deep in Saturn's well-mixed atmosphere, where high temperatures and pressures make in situ data collection challenging. The proposed mission concept, targeted for a 2015 launch, consists of a fly-by spacecraft and two identical instrument-carrying shallow probes. Entry probes shall perform in situ elemental abundance measurements to pressures of at least 10 bars and also characterize water content to 100 bars via microwave radiometry remote sensing. Here the authors present the proposed probe and flyby spacecraft systems, a detailed mission design illustrating the viability of the mission concept, and the critical science objectives that would achieved from a successful mission.