Detection of infrared biosignatures of Earth – like primitive atmospheres in transiting exoplanets

ABREVAYA X.C.; MENESES GOYTIA, S.; CROCKETT, C.

Seattle, Washington, USA

Workshop; Research Focus Workshop 09; 2009

University of Washington and NASA Astrobiology Institute

&amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;!-- /* Font Definitions */ @font-face {font-family:"MS Mincho"; panose-1:2 2 6 9 4 2 5 8 3 4; mso-font-alt:"&amp;amp;amp;amp;amp;amp;amp;amp;amp;#65325;&amp;amp;amp;amp;amp;amp;amp;amp;amp;#65331; &amp;amp;amp;amp;amp;amp;amp;amp;amp;#26126;&amp;amp;amp;amp;amp;amp;amp;amp;amp;#26397;"; mso-font-charset:128; mso-generic-font-family:roman; mso-font-format:other; mso-font-pitch:fixed; mso-font-signature:1 134676480 16 0 131072 0;} @font-face {font-family:"@MS Mincho"; panose-1:0 0 0 0 0 0 0 0 0 0; mso-font-charset:128; mso-generic-font-family:roman; mso-font-format:other; mso-font-pitch:fixed; mso-font-signature:1 134676480 16 0 131072 0;} /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-parent:""; margin:0cm; margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:12.0pt; font-family:"Times New Roman"; mso-fareast-font-family:"Times New Roman"; mso-ansi-language:EN-US; mso-fareast-language:EN-US;} @page Section1 {size:612.0pt 792.0pt; margin:70.85pt 3.0cm 70.85pt 3.0cm; mso-header-margin:36.0pt; mso-footer-margin:36.0pt; mso-paper-source:0;} div.Section1 {page:Section1;} --&amp;amp;amp;amp;amp;amp;amp;amp;amp;gt; Hypothesis   Evidence suggests that the inhabitants of a young, anoxic Earth would have been micro-organisms like archaea and bacteria. The infrared spectroscopic capabilities of the planned James Webb Space Telescope will be such that the biological products of these organisms will be detectable in the atmospheres of transiting exoplanets.  We propose to use the high S/N capabilities of NIRSpec and MIRI on JWST to detect molecules of biological origin.  Confirmation of the presence of these compounds will constitute strong evidence for the existence of anaerobic organisms on the surface of these worlds.      Description   The exoplanets that we would like to monitor, through transit spectroscopy, are those that would have a very similar atmosphere to the primitive Earth before it was oxygenated. We use Haqq-Misra et al.’s (2008) composition of the Earth’s primitive atmosphere (Archean period) which consisted of CH4, C2H6, CO2 and H2O.   The reason why we chose these conditions is because they represent the Earth at its early stages (t < 2.4 Gy) on which simple organisms such as archaea and bacteria were already present. This is assumed because the most ancient microfossils are dated to be 3.47 ± 0.50 Gy old and belong to cyanobacteria (McClendon, 1999). In addition, these microorganisms are capable of producing organic compounds that could be detected by infrared spectroscopy. We propose that these molecules could be possible candidates for biomarkers in an extrasolar planet and its detection could be indicative of the presence of unicellular life. If this is possible, not only the molecule itself must be detected but also some of the precursors and/or the additional products of the reactions that will be done by these microorganisms.