Abstract:
:Over the next two decades, NASA and ESA are planning a series of space-based observatories to find Earth-like planets and determine whether life exists on these planets. Previous studies have assessed the likelihood of detecting life through signs of biogenic gases in the atmosphere or a red edge. Biogenic gases and the red edge could be signs of either single-celled or multicellular life. In this study, we propose a technique with which to determine whether tree-like multicellular life exists on extrasolar planets. For multicellular photosynthetic organisms on Earth, competition for light and the need to transport water and nutrients has led to a tree-like body plan characterized by hierarchical branching networks. This design results in a distinct bidirectional reflectance distribution function (BRDF) that causes differing reflectance at different sun/view geometries. BRDF arises from the changing visibility of the shadows cast by objects, and the presence of tree-like structures is clearly distinguishable from flat ground with the same reflectance spectrum. We examined whether the BRDF could detect the existence of tree-like structures on an extrasolar planet by using changes in planetary albedo as a planet orbits its star. We used a semi-empirical BRDF model to simulate vegetation reflectance at different planetary phase angles and both simulated and real cloud cover to calculate disk and rotation-averaged planetary albedo for a vegetated and non-vegetated planet with abundant liquid water. We found that even if the entire planetary albedo were rendered to a single pixel, the rate of increase of albedo as a planet approaches full illumination would be comparatively greater on a vegetated planet than on a non-vegetated planet. Depending on how accurately planetary cloud cover can be resolved and the capabilities of the coronagraph to resolve exoplanets, this technique could theoretically detect tree-like multicellular life on exoplanets in 50 stellar systems.
journal_name
Astrobiologyjournal_title
Astrobiologyauthors
Doughty CE,Wolf Adoi
10.1089/ast.2010.0495subject
Has Abstractpub_date
2010-11-01 00:00:00pages
869-79issue
9eissn
1531-1074issn
1557-8070journal_volume
10pub_type
杂志文章相关文献
ASTROBIOLOGY文献大全abstract::Both hydrogen and methane are consistently discharged in large quantities in hydrothermal fluids issued from ultramafic-hosted hydrothermal fields discovered along the Mid-Atlantic Ridge. Considering the vast number of these fields discovered or inferred, hydrothermal fluxes represent a significant input of H2 and CH4...
journal_title:Astrobiology
pub_type: 杂志文章,评审
doi:10.1089/ast.2014.1198
更新日期:2015-05-01 00:00:00
abstract::Water, vital for life, not only maintains the integrity of structural and metabolic biomolecules, it also transports them in solution or colloidal suspension. Any flow of water through a dormant or fossilized microbial community elutes molecules that are potentially recognizable as biomarkers. We hypothesize that the ...
journal_title:Astrobiology
pub_type: 杂志文章
doi:10.1089/153110701753198936
更新日期:2001-07-01 00:00:00
abstract::Bacterial endospores in the genus Bacillus are considered good models for studying interplanetary transfer of microbes by natural or human processes. Although spore survival during transfer itself has been the subject of considerable study, the fate of spores in extraterrestrial environments has received less attentio...
journal_title:Astrobiology
pub_type: 杂志文章
doi:10.1089/ast.2005.5.536
更新日期:2005-08-01 00:00:00
abstract::Meaningful motion is an unambiguous biosignature, but because life in the Solar System is most likely to be microbial, the question is whether such motion may be detected effectively on the micrometer scale. Recent results on microbial motility in various Earth environments have provided insight into the physics and b...
journal_title:Astrobiology
pub_type: 杂志文章,评审
doi:10.1089/ast.2015.1376
更新日期:2016-10-01 00:00:00
abstract::Two major parameters influencing the survival of Bacillus subtilis spores in space and on bodies within the Solar System are UV radiation and vacuum, both of which induce inactivating damage to DNA. To date, however, spore survival and DNA photochemistry have been explored only at the extremes of Earth-normal atmosphe...
journal_title:Astrobiology
pub_type: 杂志文章
doi:10.1089/153110702762470518
更新日期:2002-01-01 00:00:00
abstract:UNLABELLED:In this paper, percolation theory is employed to place tentative bounds on the probability p of interstellar travel and the emergence of a civilization (or panspermia) that colonizes the entire Galaxy. The ensuing ramifications with regard to the Fermi paradox are also explored. In particular, it is suggeste...
journal_title:Astrobiology
pub_type: 杂志文章
doi:10.1089/ast.2015.1411
更新日期:2016-06-01 00:00:00
abstract::Oligonucleotides are structurally similar to short RNA strands. Therefore, their formation via non-enzymatic reactions is highly relevant to Gilbert's RNA world scenario (1986) and the origin of life. In laboratory synthesis of oligonucleotides from monomers, it is necessary to remove the water molecules from the reac...
journal_title:Astrobiology
pub_type: 杂志文章
doi:10.1089/ast.2007.0138
更新日期:2007-10-01 00:00:00
abstract::Recent discoveries about Europa--the probable existence of a sizeable ocean below its ice crust; the detection of hydrated sodium carbonates, among other salts; and the calculation of a net loss of sodium from the subsurface--suggest the existence of an alkaline ocean. Alkaline oceans (nicknamed "soda oceans" in analo...
journal_title:Astrobiology
pub_type: 杂志文章
doi:10.1089/153110702753621394
更新日期:2002-04-01 00:00:00
abstract::The Mars Organic Analyzer (MOA) has enabled the sensitive detection of amino acid and amine biomarkers in laboratory standards and in a variety of field sample tests. However, the MOA is challenged when samples are extremely acidic and saline or contain polyvalent cations. Here, we have optimized the MOA analysis, sam...
journal_title:Astrobiology
pub_type: 杂志文章
doi:10.1089/ast.2009.0357
更新日期:2009-11-01 00:00:00
abstract::Stromatolite structures in Early Archean carbonate deposits form an important clue for the existence of life in the earliest part of Earth's history. Since Mars is thought to have had similar environmental conditions early in its history, the question arises as to whether such stromatolite structures also evolved ther...
journal_title:Astrobiology
pub_type: 杂志文章
doi:10.1089/ast.2009.0388
更新日期:2010-04-01 00:00:00
abstract::The chemical basis of life involves more than simply the presence of biological molecules; biochemical systems embody a complex network of reactions with characteristic topological features. At the same time, chemical complexity is also present in nonbiological contexts, inviting us to clarify the relationship between...
journal_title:Astrobiology
pub_type: 杂志文章
doi:10.1089/ast.2011.0674
更新日期:2012-01-01 00:00:00
abstract::Modern ecological niches are teeming with an astonishing diversity of microbial life in biofilms closely associated with mineral surfaces, which highlights the remarkable success of microorganisms in conquering the challenges and capitalizing on the benefits presented by the mineral-water interface. Biofilm formation ...
journal_title:Astrobiology
pub_type: 杂志文章
doi:10.1089/ast.2011.0776
更新日期:2012-08-01 00:00:00
abstract::This review of material relevant to the Conference on Biosignature Preservation and Detection in Mars Analog Environments summarizes the meeting materials and discussions and is further expanded upon by detailed references to the published literature. From this diverse source material, there is a detailed discussion o...
journal_title:Astrobiology
pub_type: 杂志文章,评审
doi:10.1089/ast.2016.1627
更新日期:2017-04-01 00:00:00
abstract::The aim of this study was to examine team functioning within the context of the AMADEE 18 Mars analog project, which took place in Oman in the winter of 2018. Five "Analog Astronauts" participated in this study. Each completed measures of individual-level variables, including demographics and personality, before the s...
journal_title:Astrobiology
pub_type: 杂志文章
doi:10.1089/ast.2019.2035
更新日期:2020-11-01 00:00:00
abstract::Astrobiology is an inherently interdisciplinary area of study, demanding communication across multiple fields: astronomy, geochemistry, planetary science, and so on. Successful communication requires that researchers be aware of the basic findings, open questions, and tools and techniques of allied fields and possess ...
journal_title:Astrobiology
pub_type: 杂志文章
doi:10.1089/ast.2017.1710
更新日期:2018-03-01 00:00:00
abstract::The Atacama Desert has long been considered a good Mars analogue for testing instrumentation for planetary exploration, but very few data (if any) have been reported about the geomicrobiology of its salt-rich subsurface. We performed a Mars analogue drilling campaign next to the Salar Grande (Atacama, Chile) in July 2...
journal_title:Astrobiology
pub_type: 杂志文章
doi:10.1089/ast.2011.0654
更新日期:2011-12-01 00:00:00
abstract::To the astrobiologist, Enceladus offers easy access to a potential subsurface biosphere via the intermediacy of a plume of water emerging directly into space. A direct question follows: If we were to collect a sample of this plume, what in that sample, through its presence or its absence, would suggest the presence an...
journal_title:Astrobiology
pub_type: 杂志文章
doi:10.1089/ast.2016.1611
更新日期:2017-09-01 00:00:00
abstract::We observed 20-200 m sized low-albedo seepage-like streaks and their annual change on defrosting polar dunes in the southern hemisphere of Mars, based on the Mars Orbiter Camera (MOC), High Resolution Stereo Camera (HRSC), and High Resolution Imaging Science Experiment (HiRISE) images. The structures originate from da...
journal_title:Astrobiology
pub_type: 杂志文章
doi:10.1089/ast.2007.0212
更新日期:2009-01-01 00:00:00
abstract::Ultraviolet (UV) irradiation on the surface of Mars is an important factor that affects the survivability of microorganisms on Mars. The possibility of martian brines made from Fe2(SO4)3, MnSO4, and MgSO4 salts providing a habitable niche on Mars via attenuation of UV radiation was investigated on the bacteria Bacillu...
journal_title:Astrobiology
pub_type: 杂志文章
doi:10.1089/ast.2020.2285
更新日期:2020-11-25 00:00:00
abstract::Jökulhlaups are terrestrial catastrophic outfloods, often triggered by subglacial volcanic eruptions. Similar volcano-ice interactions were likely important on Mars where magma/lava may have interacted with the planet's cryosphere to produce catastrophic floods. As a potential analogue to sediments deposited during ma...
journal_title:Astrobiology
pub_type: 杂志文章
doi:10.1089/ast.2009.0425
更新日期:2010-06-01 00:00:00
abstract::The NASA Astrobiology Roadmap provides guidance for research and technology development across the NASA enterprises that encompass the space, Earth, and biological sciences. The ongoing development of astrobiology roadmaps embodies the contributions of diverse scientists and technologists from government, universities...
journal_title:Astrobiology
pub_type: 杂志文章
doi:10.1089/153110703769016299
更新日期:2003-07-01 00:00:00
abstract::Properties of avenues of transformation and their mutualism with forms of organization in dynamic systems are essential for understanding the evolution of prebiotic order. We have analyzed competition between two avenues of transformation in an A↔B system, using the simulation approach called BiADA (Biotic Abstract Du...
journal_title:Astrobiology
pub_type: 杂志文章
doi:10.1089/ast.2012.0933
更新日期:2013-05-01 00:00:00
abstract::During three low-altitude (99, 66, 66 km) flybys through the Enceladus plume in 2010 and 2011, Cassini's ion neutral mass spectrometer (INMS) made its first high spatial resolution measurements of the plume's gas density and distribution, detecting in situ the individual gas jets within the broad plume. Since those fl...
journal_title:Astrobiology
pub_type: 杂志文章
doi:10.1089/ast.2017.1647
更新日期:2017-09-01 00:00:00
abstract::The self-assembly of simple amphiphiles like fatty acids into cell-like membranous structures suggests that such structures were available on prebiotic Earth to support the origin of cellular life. However, the composition of primitive membranes remains unclear because the physical properties of the aqueous environmen...
journal_title:Astrobiology
pub_type: 杂志文章
doi:10.1089/ast.2009.0384
更新日期:2009-12-01 00:00:00
abstract::The γ-radiolysis of fullerenes (C60 and C70) was performed to investigate the role of fullerenes as a carbon source in building organic molecules in astrophysical ice analog media. Mass spectrometric analyses and the sequential collision-induced dissociation processes enabled us to determine the plausible chemical str...
journal_title:Astrobiology
pub_type: 杂志文章
doi:10.1089/ast.2018.1905
更新日期:2019-07-01 00:00:00
abstract::Formation of microtubules in volcanic glass from subsurface environments has been widely attributed to in situ activity of micro-organisms, but evidence directly linking those structures to biological processes remains lacking. Investigations into the alternative possibility of abiotic tubule formation have been limit...
journal_title:Astrobiology
pub_type: 杂志文章
doi:10.1089/ast.2017.1811
更新日期:2019-01-01 00:00:00
abstract::The possible meteorite parent body origin of Earth's pregenetic nucleobases is substantiated by the guanine (G), adenine (A), and uracil (U) measured in various meteorites. Cytosine (C) and thymine (T), however, are absent in meteorites, making the emergence of an RNA and later RNA/DNA/protein world problematic. We in...
journal_title:Astrobiology
pub_type: 杂志文章
doi:10.1089/ast.2015.1451
更新日期:2016-11-01 00:00:00
abstract::The hyperarid core of the Atacama Desert is one of the driest and most inhospitable places on Earth, where life is most commonly found in the interior of rocks (i.e., endolithic habitats). Due to the extreme dryness, microbial activity in these habitats is expected to be low; however, the rate of carbon cycling within...
journal_title:Astrobiology
pub_type: 杂志文章
doi:10.1089/ast.2012.0854
更新日期:2013-07-01 00:00:00
abstract::Initially, Raman spectroscopy was a specialized technique used by vibrational spectroscopists; however, due to rapid advancements in instrumentation and imaging techniques over the last few decades, Raman spectrometers are widely available at many institutions, allowing Raman spectroscopy to become a widespread analyt...
journal_title:Astrobiology
pub_type: 杂志文章
doi:10.1089/ast.2013.1034
更新日期:2013-10-01 00:00:00
abstract::This experiment was aimed at establishing, for the first time, the survival capability of lichens exposed to space conditions. In particular, the damaging effect of various wavelengths of extraterrestrial solar UV radiation was studied. The lichens used were the bipolar species Rhizocarpon geographicum and Xanthoria e...
journal_title:Astrobiology
pub_type: 杂志文章
doi:10.1089/ast.2006.0046
更新日期:2007-06-01 00:00:00