Abstract
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.