Workshop on the Study of the Ice Giant Planets (2014) 2006.pdf

Wave features of the Neptune’s satellites: Triton, Proteus, Nereid Kochemasov G.G., IGEM of the Russian Academy of Sciences,

Satellites in the Solar system bear traces of various wave processes as they are simultaneously involved in three cyclic movements: galactic (together with Sun and planets), circumstellar (with planets) and around planets. The Neptune’s icy satellites allow observing some of these features captured by the Voyager 2 images (Aug. 1989). Most spectacular is the north-south tectonic dichotomy of Triton – replica of the martian dichotomy but in a rocky body (2πR-structure). The Triton’s bright south is opposed with its dark north (Fig. 1, 2). A fretted boundary between these terrains could be compared with martian “chaoses” – also broken crust. The lighter southern terrain shows dark markings oriented by atmospheric winds. This dark material (similar to hydrocarbons of Titan?) penetrates into the light crust through fractures reaching the deeper layers with the darker material. It probably is represented at vast terrains of the somewhat subsided northern hemisphere. Its peculiar “cantaloupe” texture of tightly disposed regular rings could be produced under contraction due to subsidence. Uniform regularly spaced rings have diameters on average about ~17-18 km (5-25 km) (Fig. 3). This size is calculated according to the wave dependence between tectonic granule size and orbital frequency (for Triton it is 1/5.9 days and R=1350 km) [1]. The next large satellite is Proteus (R=208 km, frequency 1/1.12 days). Its small granule size due to a very fast orbit is not resolved, but a modulated size ~20 km is well observed [2]. The circumsolar granule is 41πR, the around Neptune granule is πR/1300, the modulated granule is πR/32 (41 x 1/1300) = ~20 km. (Fig. 4). An intriguing similarity of tectonic granulations is between two very different bodies: Earth and satellite Nereid (Fig. 5, 6). What is common – their orbital frequencies: Earth 1/365 days, Nereid 1/360 (a very rare Earth’s counterpart!). Due to these one could expect a relative similarity of their tectonic granules sizes. This is the case (Fig. 5, 6). References: [1] Kochemasov G.G. (1998). Tectonic dichotomy, sectoring and granulation of Earth and other celestial bodies // Proceedings of the International Symposium on New Concepts in Global Tectonics, “NCGT-98 TSUKUBA”, Geological Survey of Japan, Tsukuba, Nov 20-23,1998, p. 144-147. [2] Kochemasov G.G. (2000) Orbiting frequency modulation in Solar system and its imprint in shapes and structures of celestial bodies // XXXII microsymposium on comparative planetology, Abstracts, Moscow, Vernadsky Inst., 88-89.

Fig.1.Triton, PIA02246 Fig. 2.Triton, contact of bright & dark terrains Fig. 3. “Cantaloupe” R=1350 km PIA00060 texture, PIA00061, frame 220 km long

Fig. 4.Proteus with strips of granules Fig. 5. Nereid, PIA00054 Fig. 6. Earth, R=200 km, 4_7165b…jpg R= 170 km PIA04159