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36 -- Water and Life: Redefining the Habitable Zone of Terrestrial Planets.
THURSDAY, April 17, 2008: AFTERNOON
Alexander Pavlov
Lunar and Planetary Laboratory, University of Arizona
University of Arizona
Tuscon, AZ, USA
Chris McKay
NASA Ames Research Center
Moffett Field, CA USA
Description
At present and in the near future any search for life will be mostly limited to planetary surfaces or shallow subsurface environments. Given that water is the basic necessity for life, traditionally the habitable zone (HZ) was defined as the range of distances from a star within which a terrestrial planet could maintain moderate average surface temperatures and atmospheric pressures that allow the presence of liquid water on its surface. However, recent observations of Mars suggest that a planet can maintain liquid water at specific locations for some periods of time even though the overall temperatures are below freezing. Furthermore recent experiments on various microorganisms suggest that biota can survive extremely cold, hot and dry conditions and do not need stable bodies of open water on the planetary surface for active growth. Collectively, such studies suggest that surface or shallow subsurface biospheres, potentially detectable by future space missions, can survive and grow outside the traditional HZ.This session invites biologists, climate modelers and planetary scientists to critically evaluate and redefine the edges of the HZ based on recent observations of liquid water features on Mars, climate modeling of the terrestrial planets and studies of microbial growth in extreme environments.
We particularly invite submissions focused on two broad themes. First, we will explore various possibilities for liquid water on the terrestrial planets outside the traditional HZ. Second, we will discuss how much water and what temperatures are necessary for the survival and active growth of various microorganisms on planetary surfaces or shallow subsurface environments.
ORAL SESSION
3:15 36-04-O. Planets Formed in Habitable Zones of M Dwarf Stars Probably Are
Deficient in Volatiles J. Lissauer
3:30 36-09-O. Slow Hydrogen Escape on the Early Earth: Implications for the Redox
State of the Prebiotic Terrestrial Atmosphere S. Stevenson, A. Pavlov, R. Yelle
3:45 36-10-O. Climate on Planets at the Inner Edge of the Habitable Zone [invited]
K. Zahnle, Y. Abe, A. Abe-Ouchi, N.H. Sleep
4:00 36-01-O. Recovery from Snowball Earth States C. Cooper, A.A. Pavlov
4:15 BREAK
4:30 36-05-O. Life on Planets at the Inner Edge of the Habitable Zone [invited]
C. McKay, C. Conley, A.F. Davila, L. Fletcher, R. Navarro-Gonzalez, F. Rainey, H. Sun,
K. Warren-Rhodes, J.Wierzchos
4:45 36-07-O. The States of Water in Shallow Planetary Subsurfaces D. Möhlmann
5:00 36-08-O. Habitable Zone for Terrestrial-like Icy Planets without Liquid Water
on Surface [invited] A. Pavlov, V. Shelegedin, M. Vdovina, A.A. Pavlov
5:15 36-06-O. A Global Planetary Habitability Model A. Mendez
POSTERS
36-02-P. Frozen Environments: Extending the Habitable Zone and Hedging Against
Extinction J. Deming
36-03-P. The Case for a Cold and Wet Mars A. Fairen, A. Davila, L. Duport, E. Uceda, D. Lim,
R. Amils, C. McKay