The channels, lakes and rivers that have been seen by Cassini/Hugyens
were likely formed by liquid methane that rained down on Titan's surface.
In order to understand this methane-based hydrological cycle,
one of the best pieces of data we have are observations of Titan's
clouds (Schaller et al. 2006a and 2006b).
Recently, I have developed a ground-based cloud monitoring program with IRTF.
This program, combined with occasional adaptive optics images
from Keck and images from Cassini flybys will help us to understand how
Titan's meteorological cycle changes during its 29-year long season.
Surfaces of Kuiper Belt Objects
Unlike Pluto and Eris, the vast
majority of Kuiper belt objects are too small and too hot to
retain volatile ices like methane, molecular nitrogen and carbon
monoxide on their surfaces to the
present day. As a result, their infrared spectra are either dominated
by involatile water ice or dark featureless material (Barkume et al. 2007).
To understand the dichotomy between volatile rich and volatile free
surfaces in the outer solar system,
we constructed a simple model of
atmospheric escape of volatile ices over the age of the solar system
(Schaller and Brown 2007a).
An interesting prediction of this model is that Quaoar, an object
about half the size of Pluto, should be
just capable of retaining volatile ices to the present day. This past
April, we observed Quaoar with NIRSPEC on the Keck Telescope
and found that it does indeed contain methane ice on its surface.
(Schaller and Brown 2007b).
