Icarus http://doi.org/rgc (2014)

Triton, Neptune's largest moon, is thought to have formed in the Kuiper Belt, the icy region of the Solar System that lies beyond the planets. Numerical modelling of the thermal evolution of Triton suggests that its geologically active surface could be shaped by tidal heating because of its unusual orbit around Neptune.

Credit: © NASA / JPL

Francis Nimmo at the University of California, Santa Cruz, USA, and John Spencer at the Southwest Research Institute, USA, assessed the interior evolution of Triton following its capture by Neptune. Assuming that Triton's youthful surface with few craters — as imaged by the Voyager 2 spacecraft — requires convection, a present-day source of heating is required to permit a long-lived ocean beneath a convecting ice shell. The researchers use analytical and numerical models to show that heating generated by tidal sloshing within the ocean is sufficient to drive deformation of the icy surface when Triton's unusually oblique orbit is taken into account.

Although Pluto also formed in the Kuiper Belt, the researchers predict that similar tidal heating is unlikely to occur on the dwarf planet, suggesting that NASA's New Horizon mission — expected to arrive at Pluto in 2015 — may encounter few signs of recent geological activity.