Comparative Planetology of Earth and Titan through Analog Research

Saturn’s moon Titan exhibits remarkable parallels with Earth in a range of geophysical and geological processes not found elsewhere in the solar system at the present day. These include a nitrogen-rich atmosphere with a condensable gas - methane replacing water - leading to an active meteorological cycle with rainfall and surface expressions including rivers, lakes and seas, and the dissolution of karstic terrain. Other phenomena such as craters, dunes, and tectonic features are found elsewhere - e.g. on Mars and Venus - but their continuing alteration by pluvial, fluvial, and lacustrine processes can be studied only on Earth and Titan. Titan also hosts a subsurface liquid water ocean with similarities to the Earth as well as ocean worlds such as Europa and Enceladus. Here, we describe the geophysical and geological parallels between Earth and Titan and suggest yet-underexploited possibilities for field analog research to gain new knowledge about these processes. To date, Titan’s much colder temperature and distinct atmospheric and surface compositions have led to a skepticism with regard to usefulness of terrestrial analogs. Our conclusion, however, is that a much larger range of useful field analog work is possible and this work will substantially enhance our knowledge of both worlds. Such investigation will supplement the existing sparse data for Titan returned by space missions, will greatly enhance our understanding of such datasets, and will help to provide science impetus and goals for future missions.