I became a member of the New Horizons spacecraft team just in time to participate in the flyby of Pluto on 14th July 2015. That flyby returned our first close-up images of a Kuiper Belt Object, including magnificent views like this one:

I recently finished a long paper on determining Pluto’s size and shape as accurately as possible. Doing so is important because it might tell us about Pluto’s internal evolution, for instance whether or not it has a subsurface ocean. We are also looking for flexural features, which will tell us how rigid the crust of Pluto is, in a manner similar to the satellites Ariel or Dione. Likewise, the relaxation state of big craters will also tell us about the rigidity of the crust.

Another paper I just published has to do with the deep nitrogen-filled basin called Sputnik Planitia. I argued that its location suggests that it rolled Pluto over, and that to do so there must have been an ocean beneath the surface. Pam Engebretson came up with this nice artist’s impression of what Pluto looks like in cross-section:


Although a few papers have been written, there’s still an enormous amount of work left to do.


Here is a list of recent Pluto-related papers:


Mean radius and shape of Pluto and Charon from New Horizons images, F. Nimmo, O. Umurhan, C.M. Lisse, C.J. Bierson et al. Icarus , 287 12-29, 2017 Reprint

Charon tectonics, R.A. Beyer, F. Nimmo, W.B. McKinnon, J.M. Moore et al. Icarus , 287 161-174, 2017 Reprint

Reorientation of Sputnik Planitia implies a subsurface ocean on Pluto, F. Nimmo, D.P. Hamilton, W.B. McKinnon, P.M. Schenk, R.P. Binzel, C.J. Bierson, R.A. Beyer, J.M. Moore, S.A. Stern, H.A. Weaver, C.B. Olkin, L.A. Young, K.E. Smith, Nature 540 94-96, 2016

New Horizons at Pluto P.M. Schenk, F. Nimmo Nature Geosci., 9, 411-412, 2016 Reprint

The geology of Pluto and Charon through the eyes of New Horizons Moore, J.M. et al., Science, 351, 1284-1293, 2016.

The Pluto system: Initial results from its exploration by New Horizons S.A. Stern et al., Science 350 292-297, 2015

Powering Triton's recent geological activity by obliquity tides: Implications for Pluto geology, F. Nimmo, J. R. Spencer, Icarus 246 2-10, 2015 Reprint

Impact basin relaxation as a probe for the thermal history of Pluto S. Kamata, F. Nimmo, J. Geophys. Res. 119, doi:10.1002/2014JE004679, 2014 Reprint

Thermal evolution of Pluto and implications for surface tectonics and a subsurface ocean, G. Robuchon, F. Nimmo, Icarus 216 426-439, 2011 Reprint



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Last Modified: 20th Nov 2017.