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Measuring and Modeling the Interplay between Planetary Orbits, Interiors, Surfaces, and Atmospheres


Buhler, Peter Benjamin (2018) Measuring and Modeling the Interplay between Planetary Orbits, Interiors, Surfaces, and Atmospheres. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/MEXZ-2586.


Typically, we only have access to observations that directly probe the instantaneous state of a planet. However, these instantaneous properties are often set by the long-term interplay between several aspects of the planet. I thus use quantitative models of the interactions between the orbital, interior, surface, and atmospheric evolution in the case of three planetary bodies (Mars, Pluto, and the extrasolar planet HAT-P-13b) to gain insight into the underlying physical processes that govern the evolution of planets.

In chapter 2, the interplay between the interior structure and orbital evolution of the gas giant exoplanet HAT-P-13b allows measurements of its orbit to reveal its interior structure. I use telescopic observations of HAT-P-13b to measure its orbit and thus determine its core mass.

In chapter 3, cell-shaped landforms on Sputnik Planitia, the surface of a vast deposit of nitrogen ice covering 5% of Pluto’s surface, are the surface expression of convection within the nitrogen ice that is driven by heat flow from Pluto’s interior. The cells have sublimation pits on them, with smaller pits near their centers and larger pits near their edges. Using a simple model, I calculate the sublimation rate of these pits, which allows the determination of a size-age relationship. I then use the spatial size distribution of pits on cells to calculate their convection rate, which constrains the plutonian heat flow and thus the interior properties of Pluto.

In chapter 4, the interplay of condensation and sublimation between the surface and atmosphere of Mars create a baffling array of uniquely martian morphologies carved into the martian residual south polar CO2 cap (RSPC). Using a multi-year baseline of high-resolution observations to track the evolution of these morphologies, I build a self-consistent conceptual framework capable of explaining the basic mechanisms that give rise to the diversity of landforms that make up the RSPC.

In chapter 5, the secular evolution of Mars' orbit drives the evolution of the equilibrium relationship between the martian atmospheric pressure and the large CO2 ice deposit on the martian south polar cap. I construct the first self-consistent conceptual framework capable of predicting the existence and form of the martian residual south polar cap and the buried CO2 deposit. I then use this framework to compute the secular pressure history of Mars.

Together, the results of these investigations provide new perspective into the fundamental processes driving the formation and evolution of planetary bodies.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:Mars, Pluto, exoplanets, HAT-P-13, planets, ices, interiors, surfaces, atmospheres, orbital dynamics
Degree Grantor:California Institute of Technology
Division:Geological and Planetary Sciences
Major Option:Planetary Sciences
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Ingersoll, Andrew P. (co-advisor)
  • Ehlmann, Bethany L. (co-advisor)
Group:Astronomy Department
Thesis Committee:
  • Ehlmann, Bethany L. (chair)
  • Ingersoll, Andrew P.
  • Avouac, Jean-Philippe
  • Tsai, Victor C.
Defense Date:17 May 2018
Non-Caltech Author Email:buhler.peter.b (AT)
Record Number:CaltechTHESIS:05312018-155112365
Persistent URL:
Related URLs:
URLURL TypeDescription adapted for ch. 2 adapted for ch. 3 adapted for ch. 4
Buhler, Peter Benjamin0000-0002-5247-7148
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:10990
Deposited By: Peter Buhler
Deposited On:01 Jun 2018 20:04
Last Modified:10 Mar 2020 23:48

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