Theses and Dissertations Collection

With a thick atmosphere, a methane-based hydrological cycle, stable bodies of standing

uid at its surface,

and many active surface processes, Saturn's largest moon Titan is surprisingly Earth-like. Methane rain

on Saturn's moon Titan makes it the only place, other than Earth, where rain interacts with the surface.

Looking at Titan is like looking back in time to understand the evolution of present day Earth from

early-Earth.

This thesis combines several studies related to Titan's hydrologic system, particularly the ways

uid

interacts with the surface of Titan. Understanding this atmosphere|surface interaction is of great importance

to understand Titan's meteorology and evolution. Follwing an introduction about the discovery

and need to study Titan, chapter 2 addresses the possible reasons behind Ontario Lacus being the solo

lake in the south pole of Titan.

In chapter 3 we discuss our novell `wet-sidewalk' observation. Basically if ground gets wetted, and

illuminated by the Sun at right geometries we get this broad specular re

ection (glint) that's super-bright.

That we've seen one near Titan's north pole means that it's rained there now coincident with north polar

summer, and furthermore we've got a new technique for monitoring when and where rainfall occurs across

Titan's surface. It is extremely dicult to detect rainfall events on Titan due to its thick atmospheric

haze and very limited opportunities to view the surface (and its changes). Our wet-sidewalk observation

using VIMS |Visual and Infrared Mapping Spectrometer, on the north pole of Titan is the rst of its

kind i.e using broad surface re

ection and the delayed north polar activity. Hence this observation and

the rainfall discovery on the north pole is of extreme importance to understand Titan's climate.

While the presence of a hydrological cycle might help explain how the depressions on Titan's surface

are lled with liquid methane, the formation mechanisms of the depressions still remain a mystery at

the end of Cassini in 2017. We address this question using a morphometric measurement methodology

(EFDA|Elliptical Fourier Descriptor Analysis) to quantify the shapes of Titan's lakes in Chapter 4. We

nd that the major variation in the shapes of lakes on Titan are from circular to elliptical followed by

longer lakes with asymmetry along their long axis and longer lakes with asymmetry along their short

axis. Also, smaller lakes on Titan are more circular indicating that probably lakes are initially formed

by a punch but evolve to get bigger with more complexities in their shoreline.

We then conclude the thesis by stating our future work about expanding the morphometric analyses

to more lakes on Titan and nding more 'wet-side walk' like features on Titan's north pole.