The EJSM Jupiter-Europa Orbiter: Planning Payload

In the decade since the first return of Europa data by the Galileo spacecraft, the scientific understanding of Europa has greatly matured leading to the formulation of sophisticated new science objectives to be addressed through the acquisition of new data. The Jupiter-Europa Orbiter (JEO) is one component of the proposed multi-spacecraft Europa Jupiter System Mission (EJSM) designed to obtain data in support of these new science objectives. The JEO planning payload, while notional, is used to quantify engineering aspects of the mission and spacecraft design, and operational scenarios required to obtain the data necessary to meet the science objectives. The instruments were defined to demonstrate the viability of meeting the measurement objectives, performing while in the background radiation environment, and the ability to meet stringent planetary protection requirements. The actual instrument suite would ultimately be the result of an Announcement of Opportunity (AO) selection process carried out by NASA. The JEO planning payload consists of a notional set of remote sensing instruments, fields-and-plasma instruments, and both X-band and Ka band telecommunications systems which provide Doppler and range data for accurate orbit reconstruction. For JEO, the sensor portions of the instruments are located on the nadir facing deck of the spacecraft while a shared chassis houses the electronics portion of the instruments making optimal use of radiation shielding mass. A spacecraft supplied 10 meter boom is deployed for use by the JEO Magnetometer. All instruments are co-aligned and nominally nadir pointing for simplification of spacecraft operations. Instrument articulation required for target motion compensation, limb viewing or other purposes will be implemented within the instrument. Spacecraft telemetry and telecommand interfaces are nominally Spacewire for high-bandwidth instruments and Mil-Std-1553 for low-bandwidth instruments. Instrument power is provided by a 28 volt bus.