Limits...
Nonphotosynthetic pigments as potential biosignatures.

Schwieterman EW, Cockell CS, Meadows VS - Astrobiology (2015)

Bottom Line: We present an interdisciplinary study of the diversity and detectability of nonphotosynthetic pigments as biosignatures, which includes a description of environments that host nonphotosynthetic biologically pigmented surfaces, and a lab-based experimental analysis of the spectral and broadband color diversity of pigmented organisms on Earth.We test the utility of broadband color to distinguish between Earth-like planets with significant coverage of nonphotosynthetic pigments and those with photosynthetic or nonbiological surfaces, using both 1-D and 3-D spectral models.We demonstrate that, given sufficient surface coverage, nonphotosynthetic pigments could significantly impact the disk-averaged spectrum of a planet.

View Article: PubMed Central - PubMed

Affiliation: 1University of Washington Astronomy Department, Seattle, Washington, USA.

ABSTRACT
Previous work on possible surface reflectance biosignatures for Earth-like planets has typically focused on analogues to spectral features produced by photosynthetic organisms on Earth, such as the vegetation red edge. Although oxygenic photosynthesis, facilitated by pigments evolved to capture photons, is the dominant metabolism on our planet, pigmentation has evolved for multiple purposes to adapt organisms to their environment. We present an interdisciplinary study of the diversity and detectability of nonphotosynthetic pigments as biosignatures, which includes a description of environments that host nonphotosynthetic biologically pigmented surfaces, and a lab-based experimental analysis of the spectral and broadband color diversity of pigmented organisms on Earth. We test the utility of broadband color to distinguish between Earth-like planets with significant coverage of nonphotosynthetic pigments and those with photosynthetic or nonbiological surfaces, using both 1-D and 3-D spectral models. We demonstrate that, given sufficient surface coverage, nonphotosynthetic pigments could significantly impact the disk-averaged spectrum of a planet. However, we find that due to the possible diversity of organisms and environments, and the confounding effects of the atmosphere and clouds, determination of substantial coverage by biologically produced pigments would be difficult with broadband colors alone and would likely require spectrally resolved data.

No MeSH data available.


Related in: MedlinePlus

A sample of Brevibacterium aurantiacum before measurement with the Ocean Optics spectrometer.
© Copyright Policy - open-access
Related In: Results  -  Collection


getmorefigures.php?uid=PMC4442567&req=5

f2: A sample of Brevibacterium aurantiacum before measurement with the Ocean Optics spectrometer.

Mentions: In both (1) and (2), the sample was allowed to dry for 1 h to remove any film of water on the surface of the sample that could cause specular reflection. The resulting cell mass was at least 0.5×0.5 cm and opaque. See Fig. 2 for an example. Growth media and dead cell matter were removed because these factors varied from strain to strain and would complicate the direct comparison of one organism to another. Their removal ensured that the spectral features observed in the subsequent reflectance spectra measurements originated from the pigmented cells.


Nonphotosynthetic pigments as potential biosignatures.

Schwieterman EW, Cockell CS, Meadows VS - Astrobiology (2015)

A sample of Brevibacterium aurantiacum before measurement with the Ocean Optics spectrometer.
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4442567&req=5

f2: A sample of Brevibacterium aurantiacum before measurement with the Ocean Optics spectrometer.
Mentions: In both (1) and (2), the sample was allowed to dry for 1 h to remove any film of water on the surface of the sample that could cause specular reflection. The resulting cell mass was at least 0.5×0.5 cm and opaque. See Fig. 2 for an example. Growth media and dead cell matter were removed because these factors varied from strain to strain and would complicate the direct comparison of one organism to another. Their removal ensured that the spectral features observed in the subsequent reflectance spectra measurements originated from the pigmented cells.

Bottom Line: We present an interdisciplinary study of the diversity and detectability of nonphotosynthetic pigments as biosignatures, which includes a description of environments that host nonphotosynthetic biologically pigmented surfaces, and a lab-based experimental analysis of the spectral and broadband color diversity of pigmented organisms on Earth.We test the utility of broadband color to distinguish between Earth-like planets with significant coverage of nonphotosynthetic pigments and those with photosynthetic or nonbiological surfaces, using both 1-D and 3-D spectral models.We demonstrate that, given sufficient surface coverage, nonphotosynthetic pigments could significantly impact the disk-averaged spectrum of a planet.

View Article: PubMed Central - PubMed

Affiliation: 1University of Washington Astronomy Department, Seattle, Washington, USA.

ABSTRACT
Previous work on possible surface reflectance biosignatures for Earth-like planets has typically focused on analogues to spectral features produced by photosynthetic organisms on Earth, such as the vegetation red edge. Although oxygenic photosynthesis, facilitated by pigments evolved to capture photons, is the dominant metabolism on our planet, pigmentation has evolved for multiple purposes to adapt organisms to their environment. We present an interdisciplinary study of the diversity and detectability of nonphotosynthetic pigments as biosignatures, which includes a description of environments that host nonphotosynthetic biologically pigmented surfaces, and a lab-based experimental analysis of the spectral and broadband color diversity of pigmented organisms on Earth. We test the utility of broadband color to distinguish between Earth-like planets with significant coverage of nonphotosynthetic pigments and those with photosynthetic or nonbiological surfaces, using both 1-D and 3-D spectral models. We demonstrate that, given sufficient surface coverage, nonphotosynthetic pigments could significantly impact the disk-averaged spectrum of a planet. However, we find that due to the possible diversity of organisms and environments, and the confounding effects of the atmosphere and clouds, determination of substantial coverage by biologically produced pigments would be difficult with broadband colors alone and would likely require spectrally resolved data.

No MeSH data available.


Related in: MedlinePlus