02191nas a2200241   4500008004100000022001400041245008000055210006900135260001200204300001400216490000700230520147500237653001801712653001901730653001301749653001301762653002901775653001401804100002501818700002501843700002401868856005701892       2024                        eng d  a1531-107400aDetectability of surface biosignatures for directly imaged rocky exoplanets0 aDetectability of surface biosignatures for directly imaged rocky  c03/2024  a283 - 2990 v243 a<p>Modeling the detection of life has never been more opportune. With next-generation space telescopes, such as the currently developing Habitable Worlds Observatory (HWO) concept, we will begin to characterize rocky exoplanets potentially similar to Earth. However, few realistic planetary spectra containing surface biosignatures have been paired with direct imaging telescope instrument models. Therefore, we use a HWO instrument noise model to assess the detection of surface biosignatures affiliated with oxygenic, anoxygenic, and nonphotosynthetic extremophiles. We pair the HWO telescope model to a one-dimensional radiative transfer model to estimate the required exposure times necessary for detecting each biosignature on planets with global microbial coverage and varying atmospheric water vapor concentrations. For modeled planets with 0&ndash;50% cloud coverage, we determine pigments and the red edge could be detected within 1000&thinsp;hr (100&thinsp;hr) at distances within 15 pc (11 pc). However, tighter telescope inner working angles (2.5 λ/<i>D</i>) would allow surface biosignature detection at further distances. Anoxygenic photosynthetic biosignatures could also be more easily detectable than nonphotosynthetic pigments and the photosynthetic red edge when compared against a false positive iron oxide slope. Future life detection missions should evaluate the influence of false positives on the detection of multiple surface biosignatures.</p>10aextremophiles10afalse positive10apigments10ared edge10areflectance spectroscopy10atelescope1 aBorges, Schuyler, R.1 aJones, Gabrielle, G.1 aRobinson, Tyler, D.  uhttps://www.liebertpub.com/doi/10.1089/ast.2023.009903243nas a2200193   4500008004100000245010700041210006900148260005600217300000800273490001000281520253500291653001502826653001702841653001302858653001702871653001802888100002502906856011802931       2024                        eng d00aIn situ and remote biosignatures from microbial mats in ephemeral streams of Fryxell Basin, Antarctica0 aIn situ and remote biosignatures from microbial mats in ephemera  aFlagstaff, AZbNorthern Arizona Universityc08/2024  a3400 vPh.D.3 a<p>Transient water-limited environments are understood to have hosted microbial communities early in Earth&rsquo;s history, and thus, may have been important ecosystems for life in ancient fluvial systems on Mars and water-limited environments on rocky Earth-like exoplanets. Similar environmental systems exist on Earth today, acting as meaningful analogs to study the preservation and detection of life in these environments. Particularly useful analogs are the McMurdo Dry Valleys of Antarctica, given their cold temperatures, aridity, elevated UV radiation exposure, and predominantly microbial ecosystem. Basins in these valleys contain ephemeral glacial meltwater streams, which contain a diversity of microbial communities that are only active when the streams are flowing ten weeks of the summer. These microbial communities were studied to examine how their in situ and remote biosignatures could inform the detection of similar life on Mars and rocky exoplanets. Specifically, these organisms were found in association with carbonate rock coatings, morphologically resembling modern and ancient stromatolites from rivers, ponds, lakes, and hot springs. Microorganisms from these communities were preserved within and influenced the formation of these coatings, becoming an additional Antarctic analog to ancient stromatolites. The presence of these carbonate coatings in an ephemeral stream suggests that processes in transient fluvial environments on Mars could have also generated coatings, which could have preserved biosignatures. We also identified pigments within these microbial communities and correlated the pigments to community composition. We determined how the reflectance spectra of these communities were influenced by their pigments, demonstrating the capability of distinguishing microbial mat community composition in visible and near-infrared spectroscopy. The results of our study indicate that pigment spectral absorptions can act as remote biosignatures which we then applied to modeling the detection of similar life on the surfaces of cold and rocky Earth-like exoplanets. The detection times of Antarctic microbial mat remote biosignatures were compared with those of anoxygenic photosynthetic and nonphotosynthetic microorganisms, accounting for false positives, to determine which biosignatures were most detectable. The results from this work demonstrate the ability of the future space-based telescope, Habitable Worlds Observatory, to detect surface life on rocky Earth-like exoplanets.</p>10aAntarctica10aastrobiology10apigments10aspectroscopy10astromatolites1 aBorges, Schuyler, R.  uhttps://www.proquest.com/dissertations-theses/em-situ-remote-biosignatures-microbial-mats/docview/3094642420/se-2