[pccgrads] TODAY (5/26): Astrobiology Colloquium: Edwin Kite --Mars and climate stability

UW PCC uwpcc at u.washington.edu
Tue May 26 09:21:17 PDT 2015

*Spring 2015 UW Astrobiology Colloquium Series*


*Tuesdays @ 3:00 p.m.*

Physics & Astronomy Auditorium Building
Room A114 (map <http://washington.edu/maps/?PAA>)

/Don't Forget...
Join us for the Astrobiology Coffee Break at 2:30! /


/This Week.../

May 26

Construction and Destruction of Mountains on Mars


*Edwin Kite* <http://www.climatefutures.com/> Assistant Professor,
University of Chicago

It is not known whether Earth's long-term climate stability is rare or
Kepler data suggest many Earth-radius habitable-zone planets lie within
reach of JWST. The fraction of these that are habitable depends on the
unknown processes that regulate long-term environmental stability. Mars'
sedimentary record is the only known archive of a major planetary
habitability transition.
No rivers flow on today's Mars, but rovers and orbiters have found >3 Ga-old
sedimentary rocks, dry rivers and paleolakes, and aqueous minerals. The
nature of the early wet era, the processes that allowed surface liquid
water, and the cause of climate deterioration are all unknown.

The "Curiosity" rover is currently exploring the moat encircling a 5km-high
sedimentary rock mound in Gale Crater. This moat-and-mound pattern is common
in Mars craters and canyons, but its origin is unknown. I will set out the
evidence that moats and mounds grew together, shaped by slope winds down the
crater and mound flanks, and discuss the implications for liquid water
sources on early Mars and for Mars habitability. If time allows, I will
discuss ongoing work on connections between time gaps in the Mars
sedimentary record (including at Gale Crater) and climate modelling of late
bursts of habitability on Mars.


/Next Week.../

May 26

Research Rotation Presentation: Measuring Gas Production by
Anoxygenic Photrophic Bacteria

*Meg Smith* <http://msmit512.wix.com/astrobiology>
UWAB Graduate Student Research Rotation Presentation

The success of detecting life on another planet is contingent upon our
understanding of possible biosignatures. In recent years, research has
focused on O_2 and O_3 as candidates for gaseous biosignatures. But it is
not just O_2 -producers who call Earth home. Microorganisms have dominated
Earth for around 80% of its history, and among the most primitive organisms
are anoxygenic phototrophs -- microbes that use electron donors other than
water and do not produce oxygen. Currently, there are no known observable
biosignature gases produced by these organisms. During my research rotation,
I worked with Dr.
Niki Parenteau, at NASA Ames Research Center, to characterize gas production
by anoxygenic photrophs using a membrane-inlet mass spectrometer
newly-acquired by the Ames group. We initially focused on biogenic S gases
that can form from small molecular weight organic compounds produced by the
phototrophs combining with sulfide. We calibrated the instrument and then
measured gas production from two samples: 1) a culture of purple non-sulfur
bacteria and 2) an environmental sample of purple sulfur bacteria that we
collected from a sulfidic hot spring in northern California. We observed
distinct changes in gas production as we exposed them to oscillating
conditions of darkness and light.
We conclude the new mass spectrometer looks promising for doing further
analysis on gas production from other microbial cultures and natural
communities. An unexpected result was that the culture of purple non-sulfur
bacteria produced CO_2 when exposed to light. The origin of this CO_2
remains unknown and deserves further investigation.

The role of interstellar molecules and large-scale mixing in
making habitable planets


*Don Brownlee <http://www.astro.washington.edu/users/brownlee/>*
Professor, University of Washington

The laboratory study of collected comet samples indicate that interstellar
solids were largely destroyed during the formation of the solar system and
that it is unlikely that interstellar molecules played a significant role in
the origin of life on Earth.Nearly all of the rocky components (most of
their mass) of the solar system's original ice-rich planetesimals appear to
have formed at high temperatures in hot inner nebula regions by the same
processes that made the best preserved nebular materials found in primitive
meteorites. The dispersion of isotopic and minor element compositions of
comet silicates differs from what is found in meteorites, suggesting that
distant solar system bodies contain an averaged mix of inner solar system
materials. These materials were derived from a broad range of nebular
regions and transported over great distances.The data suggest that comet
accretion times were longer than nebular mixing times, in contrast to
meteorites that retain regional properties because they accreted faster than
solids could be mixed between nebular regions.These results shed new insight
into the mystery of why carbon and water are two orders of magnitude less
abundant in terrestrial planets than they are in comets, the dominant class
of early solar system planetesimal.

**For the full colloquium schedule for Spring 2015, click here

_*UW Astrobiology Home Page <http://depts.washington.edu/astrobio/>*_


UW Astrobiology Program <http://depts.washington.edu/astrobio/>, Box 351580,

Seattle, WA 98195
Phone: 206.685.9237
Email:astrobio at uw.edu <mailto:astrobio at uw.edu>

(c) 2011 University of Washington <http://www.washington.edu/>


Tina Swenson
Program Administrator
UW Astrobiology Program

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