THE ROLE OF CRYOVOLCANISM IN THE FORMATION OF THE SURFACE OF NEPTUNE'S MOON TRITON.

Triton, Neptune's largest moon, has a retrograde and highly inclined orbit, tilted at an angle of approximately 157° relative to Neptune's equator. It is believed that Triton was once a large binary object in the Kuiper Belt and was gravitationally captured by Neptune during the early evolution of the Solar System. Images o f Triton obtained during the “Voyager 2” flyby in 1989 revealed a geologically young, complex, and morphologically diverse surface, showing signs of active cryovolcanism and active geysers. Triton's average density of 2.06 g/cm³ directly indicates a high content of heavy rocky material, whereas water ice and other volatiles account for only 30–35% of its mass. Unlike the ancient, heavily cratered surfaces of Saturn's or Jupiter's moons, Triton's surface appears virtually "pristine," with an average age of l ess than 100 million years. This points to a global surface -renewal process occurring over short geological timescales. Due to its synchronous rotation with Neptune, Triton's leading hemisphere always faces forward along its orbital path. This significantl y increases the frequency and energy of meteoroid impacts on the leading side. The complete absence of craters on the leading hemisphere can be explained by active endogenous processes that continuously erase surface features. Massive cryovolcanic flows of liquid brines and the sublimation- driven transport of volatiles operate globally, rapidly filling fresh impact depressions and completely renewing the icy crust. Tidal evolution is the primary source of Triton's internal energy. Triton underwent a phase of global melting of its water mantle. This facilitated the satellite's rapid gravitational differentiation, resulting in the formation of a dense rocky-metallic core and a primordial global water ocean beneath a relatively thin icy crust. The existence of a subsurface liquid ocean on Triton is a key factor driving prolonged and diverse cryovolcanic activity. Cryovolcanism plays a dominant role in the formation and evolution of the surface of Neptune's satellite, Triton. Triton remains a crucial object for understanding the evolution of icy worlds in the Solar System, combining the physical characteristics of Kuiper Belt dwarf planets with the dynamics of ocean-bearing satellites orbiting giant planets.