The Spectrophotometric Properties of Icy Worlds

Abstract

Icy worlds are the moons and small planets of the solar system which are primarily composed of volatile material, such as water, ammonia, and methane. They are geologically active bodies that may harbor the key to understanding the emergence of life, as well as natural laboratories where we can test our understanding of physical processes in environments very different from that of Earth. We study these worlds using remote sensing observations carried out by spacecraft which either orbit or flyby the target body. These spacecraft carry a range of instrumentation which observe these worlds at infrared, ultraviolet, visible, and radio wavelengths. In this thesis, I will present my investigations into the atmospheres of Pluto and Titan, as well as research on Titan’s surface processes. I use observations of Pluto taken from the Multispectral Visual Imaging Camera onboard the New Horizons spacecraft to study the particle size distribution of haze in Pluto’s atmosphere. From these results I am able to identify the rate of production of different sized particles and place constraints on the microphysical properties including charge and fractal dimension. I use observations of Titan taken from the Visual and Infrared Mapping Spectrometer formerly onboard the Cassini spacecraft to study stratospheric haze features and the spectral diversity of Titan’s equator. From the survey I performed of the band of haze I identified in Titan’s stratosphere I have found evidence supporting and expanding upon seasonal circulation models. I also determined that the stratosphere is offset from the rotation axis of Titan’s solid body and is fixed in an inertial reference frame. I developed several techniques to expand the usable Cassini data and optimize observations of Titan’s surface. From this investigation I discovered a series of compositional pathways at Titan’s equator which provide evidence to explain erosion and sediment transport processes.