Can life be transported beyond its planet of origin, and adapted to survive and thrive on the Moon? Can microorganisms be useful for life support and /in situ/ resource utilization in a sustained space exploration? These fundamental questions were recently discussed at a workshop that brought together microbiologists, planetary scientists and experts in flight experiments and hardware. The focus was on cyanobacteria as model organisms because of their antiquity on earth, metabolic diversity, resilience to adverse conditions, ability to efficiently produce oxygen and hydrogen, and the existence of advanced capabilities for their genetic manipulation. I will discuss the main findings of the workshop regarding the challenges of and a research program for establishing cyanobacteria in a lunar environment. Such a program will help to connect astrobiology with NASA's missions to the Moon.

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Our Astrobiology Spring Quarter 2008 Seminar Series concludes with Dr. Andrew Pohorille.

Autumn Quarter 2008 Astrobiology Seminar Series - TBA

PAST SPRING QUARTER 2008 SEMINARS

Tuesday, May 13, 2008

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Prof. James Kasting

Department of Geoscience
Penn State University
University Park, Pennsylvania

Was the Early Earth Hot?

Despite the faintness of the young Sun, the early Earth appears to have been warm, or perhaps even hot. Taken at face value, oxygen and silicon isotopes in ancient cherts imply a mean surface temperature of 70(ą15)^oC at 3.3 Ga ^1,2. Ancient carbonates also yield high Precambrian surface temperatures ³, as does a recently published analysis of the thermal stability of proteins which are inferred to be ancient⁴. This evidence for hot early surface temperatures must be weighed against the previously mentioned dimness of the young Sun, as well as geomorphic evidence for glaciation at 2.9 Ga, 2.4 Ga, and 0.6-0.7 Ga. Climate models with high CO₂ and CH₄ concentrations can potentially explain hot climates, but can they explain climates that transition from hot to cold, and back again, multiple times? Such models must also account for the well documented correlation between the rise of O₂ at 2.4 Ga and the Paleoproterozoic glaciations which occurred at that same time. Models that do ⁵ and do not⁶ rely on changes in seawater oxygen isotopic composition will be discussed.

References:
¹ Knauth and Lowe, GSA Bull., 2003
² Robert and Chaussidon, Nature, 2006
³ Shields and Veizer, G3, 2002
⁴ Gaucher et al., Nature, 2008
⁵ Kasting et al., EPSL, 2006
⁶ Came et al., Nature, 2007

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Tuesday, May 6, 2008. No seminar this week.

Tuesday, April 29, 2008

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Prof. Jeremy Bailey

Department of Physics
Macquarie University
Sydney, Australia

Using Polarization to Detect and Characterize Extrasolar Planets

Light scattered from planetary surfaces and atmospheres is polarized while the light of the star is unpolarized. The polarization variations around a planet's orbit provide information that is complementary to that obtainable using spectroscopy. I will describe how polarization could be used in the future to search for liquid water on extrasolar terrestrial planets by detecting the rainbow scattering from cloud droplets and the "glint" from surface oceans. Such observations should be feasible with proposed space missions such as the Terrestrial Planet Finder-Coronograph and provide a means of detecting habitable planets. I will also describe a new high- sensitivity polarimeter built to search for the polarized scattered light from Hot Jupiter type exoplanets.

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Tuesday, April 22, 2008

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Prof. Siegfried Franck

Research Scientist
Potsdam Institute for Climate Impact Research (PIK)
Potsdam, Germany

Earth System Analysis: Applications to Astrobiology

A general model for the global carbon cycle of the Earth containing the reservoirs mantle, ocean floor, continental crust, biosphere, and the kerogen, as well as the combined ocean and atmosphere reservoir is presented. The model is specified by introducing three different types of biosphere: procaryotes, eucaryotes, and complex multicellular life. We can calculate the co-evolution of the geo- and biosphere from the Archaean to the long-term future. A simplified Earth system model can be used for the investigation of the habitable zone in the solar system and in exoplanetary systems.

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Tuesday, April 15, 2008. No seminar this week.

Tuesday, April 8, 2008

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Janet Siefert, PhD

Faculty Fellow, Department of Statistics
Rice University, Houston, Texas

Stromatolites: What's sulfur got to do with it?

Stromatolites (or more generally, microbialites) are carbonate encased complex microbial communities. They were a mainstream feature of early earth and now are found only in special ecosystems that provide for bacterial domination. This talk describes the bacterial constituency and metabolism within the local context of extant microbialites. We provide evidence that at least one of the conditions for microbialite formation is the presence of sulfur cycle resident in the community. Descriptions such as these better define possible early earth conditions that proved ripe for stromatolite formation and the possibility that we might extend those constraints to the possibilities of similar biotic preservation extra terrestrially.

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Tuesday, April 1, 2008

Shawn Domagal-Goldman

Penn State Astrobiology Research Center (PSARC)
The Pennsylvania State University

New Models for the Co-evolution of Biology, Geology, and Climate on the Archean Earth

This talk will cover new conceptual models for the co-evolution of the Archean Earth. The presentation will start with a review of the geochemical data that need to be accounted for, and will continue with explanations for these data derived from results of 1-D photochemical and climate models. The seminar will also discuss the implications these models have for the evolution of Earth's surface temperature, biota, and the possibility that Gaia-like feedbacks were present on Earth at this time.

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