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SS Division Seminar

Title:The activity and evolution of Pluto’s atmosphere and ices investigated with global climate models –Speaker:Tanguy Bertrand (NPP, SST) Ames Research Center —

Abstract:On July 14, 2015, the NASA New Horizons spacecraft flew by Pluto and revealed an active frozen world, with unprecedented landscapes in the Solar System. On the surface, vast plains covered with frost and spectacular glaciers, composed of different mixtures of volatile nitrogen ices, methane, and carbon monoxide, demonstrate the complexity and the geological diversity Pluto offers. In the upper atmosphere, the photolysis of certain volatiles induced by ultraviolet photons, leads to the formation of a thin bluish organic haze, extending maximally at the North Pole.

 

These exotic, and sometimes enigmatic observations, call upon modelling efforts to complete their analysis and understand the associated mechanisms at play on Pluto.

For this purpose, we have developed numerical models to simulate Pluto’s atmosphere and surface on different timescales.

 

After a short description of the history of the New Horizons mission, the encounter with Pluto, and the major scientific discoveries made to date, I will present our latest results on the activity of the ices at astronomical, seasonal, and diurnal timescales. In particular, I will explain how the Sputnik Planitia massive nitrogen glacier formed in a topographic basin, near the equator, why the surface pressure tripled since 1988, and why the haze extends maximally at the north pole in 2015. I will also present many aspects of Pluto’s current climate: the mechanism leading to the differences of temperatures observed in Pluto’s atmosphere, the wind and circulation regimes and the formation of methane clouds.

Point of contact: delia.santiago-materese@nasa.gov