NASA Astrobiology Institute: November 2007

Speaker: Geoff Marcy (University of California, Berkeley)
Date/Time: Monday, December 3, 2007 11:00 AM PST

The measured masses and orbits of the 200 secure exoplanets within 200 parsecs reveal the processes of formation and subsequent dynamics. (One parsec is the distance at which one astronomical unit subtends an angle of 1 second of arc.) Several planets reveal information on their cores and interiors. Multiple-planet systems, especially those in resonances, inform us about migration, scattering, and capture. Planets from 5-14 Earth masses are now detectable, and several have been found. The Kepler Mission and a new 2.4-m "Automated Planet Finder" telescope at Lick Observatory portend the detection of rocky planets.

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[Source: NAI Newsletter]

NAI Central is pleased to announce the news that its recent proposal to the NASA Science Mission Directorate E/PO Program entitled "NASA and the Navajo Nation 2: The Moon" has been selected for funding. This award will enable the continued collaboration with leaders and educators from the Navajo Nation toward the production of educational materials which bring together astrobiology science and Navajo cultural knowledge, in particular of the Moon. For more information, please contact Daniella Scalice,

[Source: NAI Newsletter]

Speaker: Ariel Anbar (Arizona State University)
Date/Time: Monday, November 5, 2007 11:00 AM PST

Abstract: Many lines of evidence point to a rapid rise of atmospheric O2 between 2.45 - 2.22 billion years ago (Ga), a transition often referred to as the Great Oxidation Event (GOE). The cause of the GOE is unknown. It could have been an immediate consequence of the evolution of oxygenic photosynthesis. Alternatively, O2 biogenesis may be ancient and the GOE a consequence of an abiotic shift in the balance of oxidants and reductants at the Earth's surface that crossed a critical threshold at that time. In the latter case, oxygenic photosynthesis could have evolved long before the GOE. This debate can be addressed by looking for evidence of localized or short-lived concentrations of O2 before 2.45 Ga.