![]() Despite an exogenic solar-driven solid-state greenhouse effect within nitrogen ices being preferred initially (Kirk et al., 1990), some are starting to question this paradigm (Hansen and Kirk, 2015) in the context of observations of regionally-confined eruptive on the much smaller Enceladus.Įndogenic heating is likely, with radiogenic heating alone possibly providing sufficient heat to sustain an ocean over ~4.5 Ga (Gaeman et al., 2012). Candidate endogenic features include: a network of tectonic structures, including most notably long linear features which appear to be similar to Europa’s double ridges (Prockter et al., 2006) several candidate cryovolcanic landforms (Croft et al., 1995), best explained by the same complex interaction among tidal dissipation, heat transfer, and tectonics that drives resurfacing on Europa, Ganymede, and Enceladus widespread cantaloupe terrain, unique to Triton, is also suggested non-uniquely to be the result of vertical (diapiric) overturn of crustal materials (Schenk and Jackson, 1993) and several particulate plumes and associated deposits. ![]() The lack of compositional constraints obtained during Voyager, largely due to the lack of an infrared spectrometer, means that many of Triton’s surface features have been interpreted as possibly endogenic based on comparative photogeology alone. This implies Triton’s surface is young, almost certainly the youngest of any planetary body in the solar system (except Io). Crater counts suggest a typical surface age of <10 Ma (Schenk and Zahnle, 2007), with more conservative upper estimates of ∼50 Ma on more heavily cratered terrains, and ∼6 Ma for the Neptune-facing cantaloupe terrain. They hint at on-going geological activity, suggesting an active interior and a possible subsurface ocean. Triton’s surface and atmosphere are remarkable, but poorly understood. Thus, comparisons between Triton and other icy objects will facilitate re-interpretation of existing data and maximize the return from prior NASA missions, including New Horizons, Galileo, Cassini and Dawn. It is this duality as both captured dwarf planet and large icy satellite that has undergone extreme collisional and tidal processing that gives us a unique target for understanding two of the Solar System's principal constituencies and the fundamental processes that govern their evolution. It nor exists as Neptune’s icy satellite, and is subject to a tidal, radiolytic, and collisional environment. It is believed that Triton began as of a Dwarf Planet originating in the KBO, and subsequently captured by Neptune. During its distant flyby in 1989, Voyager 2 captured a series of images, mostly of the southern, sub-Neptune hemisphere, establishing Triton as one of a rare class of solar system bodies with a substantial atmosphere and active geology. ![]() ![]() Neptune’s moon Triton is one of the most interesting and surprising targets observed by Voyager. ![]()
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