tion; in the meantime, ESA is continuing its studies of the Ganymede orbiter element of EJSM. When a Europa mission is flown, a key aspect of mission affordability will be adoption of the streamlined planetary protection decision framework recommended in this report.
The 2011 planetary science decadal survey also recommended that NASA consider studying a flagship mission to Enceladus (Box B.2).5 The Enceladus Orbiter would investigate the satellite’s cryovolcanic plumes, habitability, internal structure, chemistry, geology, and interaction with other bodies within the saturnian system. As is the case for a Europa orbiter, the complex gravitational environments of the saturnian system imply that the long-term stability of an orbiter about Enceladus cannot be guaranteed. Thus, special measures would be needed to ensure that the ultimate fate of the Enceladus Orbiter is consistent with planetary protection provisions.
An Enceladus Orbiter mission was accorded a lower priority than either the Europa Orbiter or a proposed Uranus Orbiter and was recommended for flight only if those other two missions could not be accomplished for