Pluto's Seasons: New Predictions for New Horizons

TL;DR

This paper presents new predictions for Pluto's seasonal volatile transport, considering recent data and models, identifying three possible atmospheric scenarios, with one favored by occultation data, pending further observations.

Contribution

It introduces a rapid volatile transport model enabling extensive parameter-space exploration and proposes three broad solutions for Pluto's atmospheric behavior based on recent data.

Findings

Three broad solutions for Pluto's atmosphere: PNV, EPP, EEC.

PNV solution aligns best with occultation data.

EEC scenario cannot be ruled out yet.

Abstract

Since the last Pluto volatile transport models were published (Hansen and Paige 1996), we have (i) new stellar occultation data from 2002 and 2006-2012 that have roughly twice the pressure as the discovery occultation of 1988, (ii) new information about the surface properties of Pluto, (iii) a spacecraft due to arrive at Pluto in 2015, and (iv) a new volatile transport model that is rapid enough to allow a large parameter-space search. Such a parameter-space search coarsely constrained by occultation results reveals three broad solutions: a high-thermal inertia, large volatile inventory solution with permanent northern volatiles (PNV); a lower thermal-inertia, smaller volatile inventory solution with exchanges between hemispheres, and a pressure plateau beyond 2015 (exchange with pressure plateau, EPP); and solutions with still smaller volatile inventories, with an early collapse of the atmosphere prior to 2015 (exchange with early collapse, EEC). PNV is favored by stellar occultation data, but EEC cannot yet be definitively ruled out without more atmospheric modeling or additional occultation observations and analysis.