Terrestrial Analogs to Titan for Geophysical Research

Saturn’s moon Titan exhibits remarkable parallels to the Earth in many geophysical processes not found elsewhere in the solar system at the present day. These include a nitrogen atmosphere with condensible gas - methane replacing the Earth’s water - leading to an active meteorology with rainfall and surface manifestations including rivers, lakes and seas, and the dissolution of karstic terrain. Other geophysical 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. Meanwhile Titan also hosts an interior liquid water ocean with similarities to the Earth as well as ocean worlds such as Europa and Enceladus. Our focus in this review paper is twofold: to describe the geophysical parallels between Earth and Titan, and to evaluate the yet-underexploited possibilities for field analog research to gain new knowledge about geophysical processes. To date, Titan’s much colder temperature and different atmospheric and crustal materials have led to a skepticism that useful analogs can be found on Earth. Our conclusion however is that a much larger range of useful field analog work is possible that 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.