  Some of the major discoveries of the recent Cassini-Huygens mission have put
Titan and Enceladus firmly on the Solar System map. The mission has
revolutionised our view of Solar System satellites, arguably matching their
scientific importance with that of their planet. While Cassini-Huygens has made
big surprises in revealing Titan's organically rich environment and Enceladus'
cryovolcanism, the mission's success naturally leads us to further probe these
findings. We advocate the acknowledgement of Titan and Enceladus science as
highly relevant to ESA's long-term roadmap, as logical follow-on to
Cassini-Huygens. In this white paper, we will outline important science
questions regarding these satellites and identify the pertinent science themes
we recommend ESA cover during the Voyage 2050 planning cycle. Addressing these
science themes would make major advancements to the present knowledge we have
about the Solar System, its formation, evolution and likelihood that other
habitable environments exist outside the Earth's biosphere.
