the planet’s composition, formation, and dynamical state [e.g. @Fole15; @Fole16]. We assert that for a planet to be “Earth-like” and habitable, it must be habitable in the same manner as the Earth. At a minimum this means the planet must sustain surface liquid water for millions to billions of years. . Because stable liquid water exists in a relatively narrow range in temperatures and pressures, the planet must have a process to regulate atmospheric temperatures. On the Earth, moderate temperatures are maintained by the incoming solar radiation combined with moderate greenhouse warming from CO$_2$, H$_2$O, and CH$_4$. Therefore, supply and regulation of these gases is key to Earth’s, and thus “Earth-like” planet’s climate. This definition is in contrast to the typical one for “Earth-like," in which a planet is defined simply as one with a bulk density characteristic of being roughly that of a mixture of metal $\pm$ rock.

The Earth’s atmospheric regulatory processes and aqueous chemistry arise from tectonics: the recycling of material between a planet’s surface and mantle. For Earth, the recycling process manifests as special case of tectonics, plate tectonics, in which oceanic crust continuously subducts into the interior and convective upwellings returning some material to the 