Vision and Voyages for Planetary Science in the - Solar System ...

• Characterize Ganymede’s unique magnetosphere and determine the methods by which the
magnetic field is generated.
• Investigate Ganymede’s origins and evolution.
• Characterize Ganymede’s gravity anomalies and place constraints on the size and
composition of its core and rocky and icy mantles.
• Study Ganymede’s interaction with the rest of the Jovian system.
• Characterize the variability of Ganymede’s atmospheric composition and structure in space
and time.
• Further characterize Callisto’s interior and subsurface ocean.
Mission Design
A mission with three distinct scientific phases was considered: the Ganymede and Callisto flyby
phase; a pump-down phase in an eccentric Ganymede orbit; and an orbital tour phase in a circular polar
orbit around Ganymede. For the “floor” mission option, the spacecraft would spend 3 months in
Ganymede orbit, with orbits of 6 months and 1 year for the “baseline” and “augmented” mission options,
respectively.
Floor mission payload included wide-angle and medium-angle cameras, magnetometer, radio
science, laser altimeter, visual/near infrared imaging spectrometer, and plasma package. The baseline
mission added a mass spectrometer and ultraviolet spectrometer. The augmented mission included all of
the above instruments plus radio and plasma wave instruments, narrow-angle camera, and sounding radar.
Each of these options employed a three-axis-stabilized, solar-powered spacecraft with
conventional bi-propellant propulsion. The preferred launch date for this mission was in May 2021 with
Ganymede arrival in 2028; two other launch opportunities are available in 2023 and 2024.
Mission Challenges
There are no significant technological risks associated with the GO mission, and there is no
further technology development required. For the spacecraft, the key required Ganymede flight system
elements are being developed and demonstrated for Jupiter applications on the Juno mission. The
instruments are all based on technology that is either highly developed or has already flown; for the
instruments, the only engineering developments necessary are in response to Ganymede’s high radiation
environment.
Conclusions
A Ganymede orbiter mission appears to be technically feasible with no required technology
development for the spacecraft, propulsion system, or instrumentation. For all moderate mission risks,
mitigation strategies have been incorporated into the final mission architecture. The mission was not
given further consideration because of the likelihood that the ESA Jupiter Ganymede Orbiter would
achieve most of the same science goals.
TITAN LAKE PROBE
A mission concept study performed by NASA’s Jet Propulsion Laboratory
PREPUBLICATION COPY—SUBJECT TO FURTHER EDITORIAL CORRECTION
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