The Europa Explorer - A Fresh Look at Exploring Europa with an RPS-Powered Spacecraft

An orbital mission to Europa has been identified as a high priority by the science community for several years. The difficulty of this type of mission, primarily due to the propulsive requirements and Jupiter's trapped radiation, led to many studies which investigated various approaches to meeting the science goals. A flagship-class Europa orbiting mission, which performs a multi-year study of the Jupiter system, can now be envisioned relying on existing technologies, having significantly more capability and returning considerably more science data than previous conventional propulsion mission concepts. This study resulted in several mission concept designs ranging significantly in capability and commensurate cost. The concept discussed herein returns three year's worth of Cassini data (~3 Tbit) in approximately 90 days around Europa. During its 3 month (90 day) Europa Prime Mission, the spacecraft would orbit Europa over 1000 times and provide three orders of magnitude more close ( < 5000 km altitude) Europa observing time than Galileo. A science group was formed to verify that the science objectives and goals were being adequately met by the mission design concept. The mission concept consists of a single orbiter which would traverse to Jupiter by means of a gravity assist trajectory and reach Jupiter ~6 years after launch, followed by an ~1 year tour of the Galilean satellites before entering Europa orbit. The Europa Prime Mission would be 90 days with high expectations of being operational for upwards of a year. Due to the significant power requirements, tight pointing requirements and intense radiation levels, this mission would be enabled by radioisotope power systems (RPSs). RPSs would be used for all onboard electrical power, with the excess heat used for thermal control of the spacecraft's subsystems. While the mission 31 baselines the use of eight Multi-mission Radioisotope Thermoelectric Generators (MMRTGs), trade studies were also performed to assess the benefits of using the General Purpose Heat Source - Radioisotope Thermoelectric Generator (GPHS-RTG), an Advanced Stirling Radioisotope Generator (ASRG), and an Advanced Radioisotope Thermoelectric Generator (ARTG). The results of the study show that a comprehensive Europa orbit mission is feasible using existing RTG technology, and that significant savings in mass and plutonium-238 usage can be realized using advanced RPS technologies expected to come on line as early as ~2016.