Date of Award

Spring 1-1-2016

Document Type


Degree Name

Doctor of Philosophy (PhD)


Astrophysical & Planetary Sciences

First Advisor

Leslie Young

Second Advisor

Fran Bagenal

Third Advisor

William Grundy

Fourth Advisor

Anne Verbiscer

Fifth Advisor

David Brain


This thesis presents analyses of the surface compositions of the icy outer Solar System objects Triton, Pluto, and Charon. Pluto and its satellite Charon are Kuiper Belt Objects (KBOs) while Triton, the largest of Neptune’s satellites, is a former member of the KBO population. Near-infrared spectra of Triton and Pluto were obtained over the previous 10+ years with the SpeX instrument at the IRTF and of Charon in Summer 2015 with the OSIRIS instrument at Keck. The Charon data were reduced by spectrophotometry using code that I wrote for this purpose. I present evidence of short-term volatile transport and the presence of the non-methane hydrocarbon ethane on Pluto and Triton, as well as uniform temperature and ammonia ice distributions on Charon. Based on previous laboratory work and the results of my analysis, I conclude that cryovolcanism is not necessary to explain the high percentage of crystalline water ice on Charon. The three “geologic” bodies, those previously visited by spacecraft, provide context for understanding the larger population of KBOs, the “astronomical” bodies that may never be visited by spacecraft. Observations of the geologic bodies can be used to better understand the atmospheric, surface, and interior processes on all KBOs through what I term “comparative KBOlogy.” Next-generation observatories, both in space and on the ground, will further contribute to our knowledge of the dominant processes that shape the surface evolution of KBOs.