Europa Explorer---An Exceptional Mission Using Existing Technology

A mission to Europa has been identified as a high priority by the science community for several years. The difficulty of an orbital mission - due primarily to the propulsive requirements and Jupiter's trapped radiation - led to many studies that investigated various approaches to meeting the science goals. The Europa Orbiter Mission studied in the late 1990s only met the most fundamental science objectives. The science objectives have evolved with the discoveries from the Galileo mission. JPL studied one concept-Europa Explorer - for a Europa orbiting mission that could meet a much - expanded set of science objectives. A study science group was formed to verify that the science objectives and goals were being adequately met by the resulting mission design concept. The Europa Explorer design emerged primarily from two key self-imposed constraints: (1) Meet the full set of identified non-lander science objectives. (2) Use only existing technology. Though other design concepts are viable for alternate program constraint sets, this paper will only discuss the results of this concept study. The Europa Explorer conducts a multi-year study of the Jupiter system, relies on existing technologies, and returns considerably more science data than previously examined conventional-propulsion mission concepts. In this mission concept, a single orbiter would traverse to Jupiter by means of a gravity assist trajectory and reach Jupiter ~6 years after launch, followed by an ~1frac12 year tour of the Galilean satellites, before entering Europa orbit. The Europa Prime Mission would be 90 days, with the expectation of being operational for upwards of a year. The flight system would return approximately three year's worth of Cassini data (~3 Tbit) during the first 90 days in Europa orbit. During this Europa Prime Mission, the flight system would orbit Europa more than 1000 times and provide three orders of magnitude more close (<5000-km altitude) Europa observing time than Galileo. The initial portion of this study resulted in a highly robust science mission as summarized above. Subsequent discussions with the Outer Planets Assessment Group (OPAG, November 2006) led to the definition of a more modest reference mission. This reference mission is also described.