Pluto's Far Side

Pluto's Antipodal Terrains Imply a Thick Subsurface Ocean and Hydrated Core

“…Indeed, a possible offset in the antipodal terrain of Sputnik Planitia was noted by Stern et al. (2020).…”

“…Near‐surface pressure gradients can produce significant deformation and surface disruption, resulting in antipodal terrains (Bowling et al., 2013; Hood & Artemieva, 2008; Schultz & Gault, 1975; Watts et al., 1991). The recently identified zone of lineations antipodal to Pluto's ancient Sputnik Planitia basin (Moore et al., 2016; Stern et al., 2020) superficially resemble antipodal terrains associated with the other largest impact basins in the Solar System, including the “hilly and lineated” terrain antipodal to Caloris Basin on Mercury (Schultz & Gault, 1975) and the disrupted terrain opposite the Imbrium basin on the Moon (Schultz & Gault, 1975). Pluto's lineations, however, are hundreds of km long and tens of kilometer wide, potentially much larger than any antipodal terrain observed elsewhere, though consistent with the large size of Sputnik Planitia relative to Pluto.…”

Equatorial mountains on Pluto are covered by methane frosts resulting from a unique atmospheric process

“…To simulate Pluto as observed in 2015, we performed a simulation similar to the one presented in Bertrand et al 16 but with the following improvements. Firstly, we used the latest topography data of the encounter hemisphere of Pluto 9 , which includes Sputnik Planitia, eastern Cthulhu, and Tartarus Dorsa (the latter being the western extent of the bladed terrain, a chain of massive, low-latitude, high-elevation deposits of CH 4 ice that have been eroded via sublimation into the eponymous blades, and which extend across much of the sub-Charon side of Pluto 11,18 ). Secondly, perennial CH 4 deposits were added on the sub-Charon side of Pluto (covered by low-resolution New Horizons imaging) wherever terrain with diagnostic characteristics of the bladed terrain was detected 18 (i.e.…”

“…The GCM reproduces well the thermal structure measured by the New Horizons spacecraft in the lower atmosphere (below 200 km altitude) and the threefold increase in surface pressure observed from stellar occultations between 1988 and 2015 with~1.1 Pa in 2015 5,22 . Recent improvements to the model include incorporation of perennial high-altitude CH 4 deposits in the equatorial regions (bladed terrain), based on mapping of Pluto's far side 18 , and the use of the latest topography from New Horizons data 9 . We use flat topography for the non-observed southern hemisphere.…”

Global climate model occultation lightcurves tested by August 2018 ground-based stellar occultation

“… The presence of high-altitude perennial 4 CH -rich deposits in the equatorial regions (known as the Bladed Terrain). These terrains are visible in the Tartarus Dorsa region (east of Sputnik Planitia) but their distinctive 4 CH absorption is seen in low resolution coverage of Pluto obtained during the New Horizons' approach phase, suggesting that they occur in patches further east along the equator (Olkin et al, 2017;Moore et al, 2018;Stern et al, 2020). In the GCM, we place a J o u r n a l P r e -p r o o f  The haze parameterization described in Bertrand and Forget (2017), which reproduces to first order the photolysis of 4 CH molecules in the upper atmosphere by Lyman- UV radiation, the production of gaseous haze precursors, and their conversion into solid particles (using a simple formation scheme with a characteristic time for aerosol growth set to 7 10 s).…”