BOX B.2
Enceladus Orbiter

Enceladus Orbiter Spacecraft

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Key Challenges

•   Planetary Protection

–   Potential modifications to design required if planned Enceladus impact disposal is not acceptable for planetary protection

•   Particle Impact Damage

–   Potential for spacecraft damage from Saturn E-ring or Enceladus plume particle impact

–   Primary concern: high-gain-antenna surface quality

•   System Power

–   Some potential for reduced science operations with assumed Advanced Stirling Radioisotope Generators (ASRG) degradation

Science Objectives

•   Investigate the internal structure, geology, and chemistry of Enceladus and plumes discovered by Cassini

•   Prepare for a potential future landing

•   Observe interactions between Enceladus and the Saturn system and explore the surfaces and interiors of Saturn’s moons

•   Key science issues addressed:

–   Investigating the nature of Enceladus’s cryovolcanic plumes

–   Providing improved measurements of plume gas and dust

–   Measuring tidal flexing, magnetic induction, static gravity, topography, and heat flow

Key Parameters

•   Payload

–   Medium Angle Imager

–   Thermal Imaging Radiometer

–   Mass Spectrometer

–   Dust Analyzer

–   Magnetometer

•   Three ASRGs

•   Launch Mass: 3,560 kg

•   Launch Date: 2023 (on Atlas V 521)

•   Orbit: Enceladus Orbit (100 km x 267 km, 62 deg inclination) Plus Saturn Satellite Tour

 

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.

ENCELADUS

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



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