Cryovolcanism?
If convective overturn is active in Sputnik Planum, one might expect
to find signs of cryovolcanic activity too. Pluto’s density, size and surface composition are similar to those of Neptune’s largest satellite, Triton, which is believed to have been captured from the early Kuiper Belt
when it was being perturbed by the migration of the outer planets. One
of Voyager 2’s biggest surprises at Neptune was the discovery of ongoing cryovolcanic activity on Triton. New Horizons did not detect any
such activity at Pluto. However, two broad-based mountains south-west
of Norgay Montes, Wright Mons (shown in Figure 14) and Piccard Mons,
could be of volcanic origin. At about 4km and 6km high respectively,
both have summit depressions which could be indicative of cryovolcanic activity. And, lacking surface craters on their flanks, they are possibly quite recent features geologically speaking.
Figure 14: This rounded mountain, named Wright Mons, has what appears to be a summit crater. It is one of two candidates for
evidence of possible recent cryovolcanism seen on Pluto by New Horizons. Credit: NASA/JHUAPL/SwRI
Dynamic atmosphere
We have spoken much above of apparent surface-atmosphere interactions. Pluto’s atmosphere was a prime target for the New Horizons
mission team. It is composed of roughly 90% Nitrogen (N2), and 10%
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