Astronomy Meets Biology: EFOSC2 and the Chirality of Life

M. Sterzik, S. Bagnulo, A. Azua, F. Salinas, J. Alfaro, F. Vicuna

A microphotograph of the cyanobacteria Chroococcidiopsis, enlarged 100 times.

ABSTRACT
Homochirality, i.e., the exclusive use of L-amino acids and D-sugar in biological material, induces circular polarisation in the diffuse reflectance spectra of biotic material. Polarimetry may therefore become an interesting remote sensing technique in the future search for extraterrestrial life. We have explored this technique and performed a laboratory experiment making an exotic use of an astronomical instrument. During a period when EFOSC2 was detached from the Nasmyth focus to host a visitor instrument at the NTT, we have observed various samples of biotic and abiotic material and measured their linear and circular polarisation spectra. Among the various targets, we have included samples of the hypolithic cyanobacteria species Chroococcidiopsis isolated from the Coastal Range of the Atacama Desert. To our knowledge, these are the first and highest precision measurements of circular polarisation using living material and obtained with an astronomical instrument.

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Last Revised: 2011 January 4th