Remote Sensing of Potential Biosignatures from Rocky, Liquid, or Icy (Exo)Planetary Surfaces

Poch, Olivier; Frey, Joachim; Roditi, Isabel; Pommerol, Antoine; Jost, Bernhard; Thomas, Nicolas (2017). Remote Sensing of Potential Biosignatures from Rocky, Liquid, or Icy (Exo)Planetary Surfaces. Astrobiology, 17(3), pp. 231-252. Mary Ann Liebert 10.1089/ast.2016.1523

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To detect signs of life by remote sensing on objects of our Solar System and on exoplanets, the characterization of light scattered by surface life material could complement possible clues given by the atmospheric composition. We reviewed the reflectance spectra of a broad selection of major biomolecules that constitute terrestrial carbon-based life from 0.4 to 2.4 μm, and we discuss their detectability through atmospheric spectral windows. Biomolecule features in the near-infrared (0.8–2.4 μm) will likely be obscured by water spectral features and some atmospheric gases. The visible range (0.4–0.8 μm), including the strong spectral features of pigments, is the most favorable. We investigated the detectability of a pigmented microorganism (Deinococcus radiodurans) when mixed with silica sand, liquid water, and water-ice particles representative of diverse surfaces of potentially habitable worlds. We measured the visible to near-infrared reflectance spectra (0.4–2.4 μm) and the visible phase curves (at 0.45 and 0.75 μm) of the mixtures to assess how the surface medium and the viewing geometry affect the detectability of the microorganisms. The results show that ice appears to be the most favorable medium for the detection of pigments. Water ice is bright and featureless from 0.4 to 0.8 μm, allowing the absorption of any pigment present in the ice to be well noticeable. We found that the visible phase curve of water ice is the most strongly affected by the presence of pigments, with variations of the spectral slope by more than a factor of 3 with phase angles. Finally, we show that the sublimation of the ice results in the concentration of the biological material onto the surface and the consequent increase of its signal. These results have applications to the search for life on icy worlds, such as Europa or Enceladus.

Item Type:

Journal Article (Original Article)

Division/Institute:

08 Faculty of Science > Physics Institute > Space Research and Planetary Sciences
08 Faculty of Science > Physics Institute
10 Strategic Research Centers > Center for Space and Habitability (CSH)
08 Faculty of Science > Physics Institute > NCCR PlanetS

UniBE Contributor:

Poch, Olivier and Thomas, Nicolas

Subjects:

500 Science
500 Science > 520 Astronomy
500 Science > 530 Physics
600 Technology > 620 Engineering

ISSN:

1531-1074

Publisher:

Mary Ann Liebert

Language:

English

Submitter:

Janine Jungo

Date Deposited:

03 Aug 2017 15:59

Last Modified:

11 Mar 2018 02:30

Publisher DOI:

10.1089/ast.2016.1523

BORIS DOI:

10.7892/boris.97274

URI:

https://boris.unibe.ch/id/eprint/97274

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