Methane on Mars and Titan: Isotopic Clues and Geochemical Pathways to Habitability

To the point

Methane on Mars and Titan may originate from geology or life, and researchers like Mumma, Formisano, and Krasnopolsky use isotopes and atmospheric observations to decide its source and plan future missions.

The Mystery of Methane on Mars and Titan
scientificamerican.com

The Mystery of Methane on Mars and Titan

It might mean life, it might mean unusual geologic activity; whichever it is, the presence of methane in the atmospheres of Mars and Titan is one of the most tantalizing puzzles in our solar system