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Towards polarimetry as a tool for the detection of extra-terrestrial life

Published online by Cambridge University Press:  24 July 2015

Stefano Bagnulo ,
Michael F. Sterzik  and
Alberto Cellino
Stefano Bagnulo
Affiliation:
Armagh Observatory, College Hill, Armagh BT1 9DG, UK. e-mail: sba@arm.ac.uk
Michael F. Sterzik
Affiliation:
European Southern Observatory, Karl-Schwarzschildstrasse 2, D-85748, Garching bei München, Germany. e-mail: msterzik@eso.org
Alberto Cellino
Affiliation:
INAF - Osservatorio Astrofisico di Torino, Pino Torinese. e-mail: cellino@oato.inaf.it
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Abstract

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Linear broadband polarimetry is used to characterize the objects of our solar system, and has also been proposed as a diagnostic tool for the atmospheres of exo-solar planets. Homochirality characterizes life as we know it and induces circular polarization in the diffuse reflectance spectra of biotic material. Hence it has been suggested that circular polarimetry may be used as a remote sensing tool for the search of extra-terrestrial life. With this motivation in mind we have decided to explore the potential of both linear and circular spectropolarimetry as a diagnostic tool for remote sensing of biotic material. We have used the calibration unit of the EFOSC2 instrument of the La Silla Observatory to obtain low resolution, but high signal to noise circular and linear spectropolarimetric measurements of a number of inorganic and organic materials. We then compare our “laboratory data” with spectropolarimetric observations of atmosphere-less bodies of our solar system and of Earthshine obtained with instruments very similar to that one used for our laboratory samples. We conclude that linear polarization measurements are more suitable than circular polarization measurements for the characterization of planetary surfaces and atmospheres, and for the search of extra-terrestrial life.

Keywords

astrobiologypolarizationminor planetsasteroids
Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 10 , Symposium S305: Polarimetry: From the Sun to Stars and Stellar Environments , December 2014 , pp. 346 - 350
Copyright
Copyright © International Astronomical Union 2015 

References

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