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

hardened technology for Io and Ganymede missions and the ability to survive microbial reduction
processes for Enceladus.
• Instrument development for future Titan missions, particularly remote-sensing instruments
capable of mapping the surface from orbit and in situ instruments needed for detailed chemical, physical,
and astrobiological exploration of the atmosphere, surface and lakes, which must operate under cryogenic
conditions. 54
Technology Development
Aerocapture should be considered as an option for delivering more mass to Titan in the future
Titan flagship mission studies, and is likely to be mission-enabling for any future Uranus and Neptune
orbiters (Chapters 7, 11, and Appendix D) mission. Further risk reduction will be required before high
value and highly visible missions will be allowed to utilize aerocapture techniques.
Plutonium power sources are of course essential for most outer planet satellite exploration, and
completion of development and testing of the new Advanced Stirling Radioisotope Power Generators
(ASRGs), is necessary to make most efficient future use of limited plutonium supplies. However
maintenance of the Multi-Mission Radioisotope Thermoelectric Generator (MMRTG) technology is also
required if an MMRTG is to be used for a Titan hot-air balloon.
Hot-air balloons at Titan will be of great utility for understanding the atmospheric processes and
chemistry. There is currently a European effort to advance this technology. 55 Titan aircraft provide a
potential alternative to balloons if plutonium supplies are insufficient to fuel an MMRTG but sufficient
for an ASRG. 56
The identification of trajectories that enable planetary missions or significantly reduce their cost
is an essential and highly cost-effective element in the community’s tool kit. 57 The history of planetary
exploration is replete with examples, and the Enceladus orbiter mission concept discussed in this report is
an example of a mission enabled by advanced trajectory analysis. A sustained investment in the
development of new trajectories and techniques for both chemical propulsion and low thrust propulsion
mission designs would provide a rich set of options for future missions.
A radiation effects risk reduction plan is in place and would be implemented as part of the Phase
A activities for an Europa Jupiter System Mission (EJSM). Future missions to Io and Ganymede will
benefit from this work and it will have to be sustained to assure that the technology base is adequate to
meet the harsh radiation environment that EJSM and future missions will encounter.
Other Infrastructure
The base for thermal protection system (TPS) technology used for atmospheric entry is fragile,
and is important for satellite science applications including aerocapture at Titan from heliocentric orbit,
and Neptune aerocapture. The technology base that supports the thermal protection systems for re-entry
vehicles was developed in the 1950s and 1960s with small advances thereafter. The near loss of the TPS
technology base endangered the development of Mars Science Laboratory which required the use of
Phenolic Impregnated Carbon Ablator (PICA) Although, PICA is an old technology, its use for MSL was
enabled by the significant investment of the Orion TPS project that was required to resurrect a technology
base that had atrophied. One very important lesson learned in this process was that several years of
intense and expensive effort can be required to implement even modest TPS improvements. 58
PREPUBLICATION COPY—SUBJECT TO FURTHER EDITORIAL CORRECTION
8-26