Scientific Colloquium
November 18, 2011
SARAH
M. HÖRST
UNIVERSITY OF COLORADO
"Do the Building Blocks of Life Exist in Titan’s
Atmosphere: Lessons from the Lab"
Does Titan's atmosphere contain
the basic building blocks of life? In this talk I will discuss
how recent measurements by NASA's Cassini spacecraft and
parallel laboratory chemistry investigations are revealing the
surprising complexity of the atmosphere of Saturn's giant moon.
Titan is unique in the solar system because it is the only moon
with a substantial atmosphere. Composed primarily of N2 and with
a surface pressure 50% greater than on the surface of Earth,
Titan’s atmosphere is the most similar atmosphere in the solar
system to that of Earth. However, Titan’s atmosphere has only
small amounts of oxygen-containing molecules, which means that
it may most strongly resemble the atmosphere of the early Earth.
These similarities provide us with the opportunity to study
chemical processes analogous to those that may have enabled the
origin of life on Earth.
Cassini's instruments are now revealing the true diversity of
Titan's atmosphere, which is significantly more complex at much
higher altitudes than anticipated. In laboratory simulations of
Titan’s atmosphere, similar to the Miller-Urey experiment,
mixtures of gases are irradiated resulting in the formation of
numerous complex organic molecules. In a recent experiment,
we’ve shown that the addition of carbon monoxide (which is
present in Titan’s atmosphere) to the standard N2/CH4 Titan
simulation gas mixture provides enough oxygen to allow for the
formation of amino acids and nucleotide bases used by life on
Earth.
I will review the current state of our understanding of Titan's
oxygen chemistry and briefly discuss how future missions to
Titan could be designed to answer questions that will remain
after Cassini.
About the Speaker:
Dr. Sarah M. Hörst is currently a NSF Astronomy and
Astrophysics Postdoctoral Fellow at the Cooperative Institute
for Research in Environmental Sciences (CIRES) at the University
of Colorado-Boulder. She received a B.S. in Planetary Science
(and literature) from the California Institute of Technology in
2004 and a Ph.D in Planetary Sciences from the University of
Arizona in 2011. Her current research interests include
understanding the organic chemistry occurring in Titan's
atmosphere and the formation and composition of aerosols in
planetary atmospheres.