Pluto's Sherpas: Studying HazE Radiative Processes and Atmosphere-Surface interactions

Overview of the project

Keywords: radiative transfer, thermal structure, general circulation, volatile cycles, orographic waves, thermal tides, sublimation waves, icy dunes, paleoclimates, glacial flow

Context: After the initial reconnaissance from remote observations, the New Horizons flyby of Pluto in 2015 unveiled a world with surprisingly variegated surface topography and composition, a remarkably active geology with glaciers and icy dunes made of volatile N2, CH4, CO ices, a H2O ice bedrock covered by dark tholins-like materials, and a chemically-rich (N2, CH4 and other hydrocarbons, CO and HCN) atmosphere with an extensive haze displaying layers, suggestive of wave activity.

Pluto shares similarities with Mars (a tenuous atmosphere with a complex climatic system driven by the redistribution cycles of volatile ices), Titan (photolytically-produced haze in a N2-CH4 atmosphere, presence of gravity waves) and Triton (similar bulk properties, surface and atmosphere composition), and is a representative of other large, volatile-rich Trans-Neptunian objects, some of which may exhibit similar atmospheres near perihelion (e.g. Eris, Makemake). Thus, in addition to its intrinsic interest, Pluto represents a new natural laboratory to study planetary climate physics and dynamics and a benchmark case to understand surface-atmosphere interactions on volatile-rich distant objects.

Objectives: With the SHERPAS project, we aim at characterizing and modeling complex surface and atmospheric processes on Pluto, interpreting existing and new observations and comparing with other planetary objects. In particular, we try to answer fundamental questions such as:

  • What are the radiative properties of the haze, and the total atmospheric energy budget?
  • How are the observed atmospheric waves generated, and how they propagate and affect Pluto's climate?
  • What are the surface-atmosphere interactions shaping the icy dunes seen across Pluto? How do these phenomena relate to elsewhere in the Solar System?

Methods: To achieve our goals, we use a hierarchy of numerical climate models of Pluto (which apply to Triton and other TNOs as well) based on universal physical equations: a 1-D radiative-convective model (1DM), a 2-D Volatile Transport Model (VTM), and a 3-D Global Climate Model (GCM). We also analyze Earth-based observations of Pluto's atmosphere and surface (including ALMA and JWST observations).

People: Collaboration between three research teams at the Laboratoire d'Etudes Spatiales et d'Instrumentation en Astrophysique (LESIA), Laboratoire de Meteorologie Dynamique (LMD), and Laboratoire de Planetologie et Geoscience (LPG).

  • PI : Tanguy Bertrand, Astronomer at LESIA
  • Emmanuel Lellouch, Astronomer at LESIA
  • François Forget, CNRS researcher at LMD
  • Aymeric Spiga, assistant professor at Sorbonne Universite and researcher at LMD
  • Ehouarn Millour, research engineer, LMD
  • Aurelien Falco, research engineer, LMD
  • Sabrina Carpy, assistant professor at Nantes University and researcher at LPG
  • Olivier bourgeois, professor at Nantes University and researcher at LPG
  • Paul Bessin, professor at Le Mans University and researcher at LPG

News:

  • We are hiring a postdoctoral researcher at LESIA ! See job description here.
  • We are hiring a PhD student at LPG ! See job description here EN . ici FR

Funding

ANR, "Programme de Recherche Collaborative", 2024-2028 (ANR-23-CE49-0006).