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

years are comparable to the largest terrestrial eruptions witnessed in human history. Io’s high heat flow
provides an analog to the terrestrial planets shortly after their formation, and its atmospheric mass loss
illuminates volatile loss mechanisms throughout the solar system. Ganymede’s surprising magnetic field
may help us to understand the dynamos in terrestrial planets, and the poorly differentiated interiors of
Callisto and Titan constrain timescales for assembly of the solar system. An understanding of Titan’s
methane greenhouse may illuminate anthropogenic greenhouse warming on Earth, or Venus’s
greenhouse, and Titan’s organic chemistry illuminates terrestrial prebiotic chemical processes. Triton
provides a valuable analog for large evolved bodies in the Kuiper belt such as Pluto and Eris.
In turn, studies of other bodies in the solar system help us to understand the giant planet satellites.
The composition and internal structure of the giant planets constrains the raw materials and formation
environments of the satellites, while the populations and compositions of primitive bodies illuminate the
current and past impact environments of the satellites.
There is much overlap between planetary satellite science goals and NASA solar and space
physics goals, 53 because many giant planet satellites are embedded in their planetary magnetospheres and
interact strongly with those magnetospheres, producing a rich variety of phenomena of great interest to
both fields.
Connections with Extrasolar Planets
The first detections of extrasolar planetary satellites may not be far off (Kepler may detect
satellite-induced planetary wobble via transit timings, for instance). When they are found, our
understanding of our own giant planet satellite systems will be essential for interpretation of the extrasolar
satellite data, both for the direct understanding of those worlds and their use as constraints on the
evolution of their primary planets. Extrasolar satellite systems will provide more habitable environments
than their primaries in many cases, and our understanding of those environments will depend heavily on
our understanding of satellites in our own solar system.
SUPPORTING RESEARCH AND RELATED ACTIVITIES
In recent years, NASA’s research and analysis (R&A) activities for the outer solar system has
been increased through the establishment of the Cassini Data Analysis Program (CDAP), the Outer
Planets Research Program (OPRP), and the Planetary Mission Data Analysis Program (PMDAP). All of
these programs have enabled understanding of outer solar system bodies to grow, and new researchers to
be trained. They are essential to harvesting the maximum possible science return from missions, whether
past (Voyager, Galileo) present (New Horizons, Cassini) or future (Juno, Europa Jupiter System Mission).
INSTRUMENTATION AND INFRASTRUCTURE
Satellite science will benefit from continued development of a wide range of instrument
technologies designed to improve resolution and sensitivity while reducing mass and power, and to
exploit new measurement techniques. Specific instrumentation requirements for the next generation of
missions to the satellites of the outer planets include:
• In the immediate future, continued support for Europa orbiter instrument development.
Europa instruments face unique challenges: they must survive not only unprecedented radiation doses,
but also pre-launch microbial reduction needed to meet planetary protection requirements.
Instrumentation for future missions will also benefit from Europa instrument development, e.g., radiation-
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