"What are possible alternative environments in which life may have originated? "
Content with the tag: “science (journal)”
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Signs of Ocean Beneath Titan's Crust?
NASA’s Cassini spacecraft has discovered evidence that points to the existence of an underground ocean of water and ammonia on Saturn’s moon Titan. The Cassini science team detail their findings in this week’s Science, explaining that radar mapping of Titan revealed a shift in landmarks on the moon’s surface of up to 30 kilometers between October 2004 and May 2007. The best explanation, they say, is an underground ocean...
March 25, 2008 / Posted by: Daniella Scalice
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Discovering Earth-like Exoplanets
In this week’s Science, astrobiologists from NAI’s University of Hawai’i Team review the prospects for discovering smaller planets more like Earth, some of which may even have conditions suitable for life. Improved techniques and the ability to monitor fainter stars now enable astronomers to discover smaller planets, particularly planets orbiting much closer to their host star than the Earth is to the Sun. This review article is based on an NAI-supported session at the May, 2007 meeting of...
October 10, 2007 / Posted by: Shige Abe
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Microbial Population Structures in the Deep Marine Biosphere
NAI’s Marine Biological Laboratory Team has a new paper in this week’s Science detailing aspects of population structure for microbial communities at two neighboring hydrothermal vents. Using environmental DNA sequencing techniques, they found the two populations reflect the geochemical conditions of each vent.
October 8, 2007 / Posted by: Shige Abe
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Oxygen in Earth's Atmosphere Before Great Oxidation Event
NAI’s Astrobiology Drilling Program supported researchers in 2004 to obtain subsurface core samples from the Hamersley Basin in Western Australia. Those samples, representing the time just before the Great Oxidation Event, have been analyzed, and two research papers detailing the results (Anbar, et al. and Kaufman, et al.) appear in September 28, 2007 issue of Science. Both groups found unexpected, correlated changes that reveal the presence of small but significant amounts of O2 in the environment 2.5 billion years...
September 27, 2007 / Posted by: Shige Abe
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Extracellular Protein-Metal Aggregates: A New Biosignature?
Deep inside a flooded mine in Wisconsin, scientists from NAI’s University of California, Berkeley Team have discovered an environment in which bacteria emit proteins that sweep up metal nanoparticles into immobile clumps. Their finding may lead to innovative ways to remediate subsurface metal toxins, and have exciting implications for identifying biosignatures on Earth and other worlds. The research, published in the June 14th issue of Science, was done in collaboration with a team from the U.S. Department of Energy’s Lawrence...
June 13, 2007 / Posted by: Shige Abe
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Liquid Water on Mars: Is It Still Flowing?
The scientific strategy of NASA’s Mars exploration can be summarized as “Follow the water.” The habitability of Mars, past or present, is intimately tied to the presence of liquid water. Since the first orbiting spacecraft, Mariner 9, surveyed the planet in the early 1970s, we have known that the Mars polar caps are composed in part of ice, and we have seen large channels cut by water that flowed on the surface billions of years ago. Two of the most important recent discoveries on Mars were “gullies” that indicate much more recent surface flows, less than a million years old, and the evidence from rovers on the surface that shallow ponds or seas of salty water must have once existed, although they may have been transient. However, all these indications of surface water are old – whether the age is measured in millions or billions of years. Now, in what looks to be one of the most important recent discoveries about Mars, we have photographic evidence that flows of liquid water have taken place in the past seven years! The change of perspective from billions or millions of years to something that happened in the twenty-first century could be profound.
January 9, 2007 / Posted by: Shige Abe
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Low Abundance Acidophilic Archea Revealed
Scientists from NAI’s University of California, Berkeley Team report in this week’s Science on their use of shotgun sequencing to uncover three novel archea present in all biofilms growing in pH 0.5 to 1.5 solutions within the Richmond Mine, California. Their results inform the problem of characterizing microbial communities and lineages which are difficult to cultivate.
December 20, 2006 / Posted by: Shige Abe
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Stardust Sample Analysis
A special issue of Science (Dec 15) includes several papers reporting on various aspects of Stardust sample analysis including an organics survey, isotopic and elemental compositions, mineralogy and petrology, and infrared spectroscopy. Many NAI researchers contributed to this comprehensive analytical campaign, including members of NAI’s Teams at the Carnegie Institution of Washington, NASA’s Ames Research Center and Goddard Space Flight Center, and NAI’s Alumni Team at the University of Washington.
December 13, 2006 / Posted by: Shige Abe
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Found: A Hyperthermophilic Nitrogen Fixer
Researchers from NAI’s Carnegie Institution of Washington Team have published in Science their findings of a novel archaeon who’s ability to fix nitrogen at 92 degrees Celcius has officially increased the upper limit of biological nitrogen fixation by 28 degrees Celcius. The hyperthermophilic methanogen was isolated from a hydrothermal vent. Thier findings could reveal a broader range of conditions for life in the subseafloor biosphere.
December 13, 2006 / Posted by: Shige Abe
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Astrobiology and Stardust
Carl Sagan once said “We are all star stuff.” But how? What does that really mean? One of the fundamental questions of astrobiology, how does life originate and evolve?, provides a structure in which to examine the relationship between life and the cosmos. Everywhere life has been found on Earth, which is essentially every place in which it has been sought, life’s intimate connection with water has also been found. Within the framework of contemplating life’s cosmic origins, one must also ask about the history of water on Earth. NASA’s Stardust mission has provided the opportunity for astrobiologists to gain deeper insight into this history.
December 13, 2006 / Posted by: Shige Abe
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Earth’s Hidden Biospheres
Two recent discoveries in astrobiology challenge many of our assumptions about an integrated biological community on Earth. At the microbial level, it seems that there may be previously hidden biospheres that exist on Earth alongside our more familiar neighbors. One such community has been found deeply buried underground, while the other lives in the sea alongside more familiar life forms.
November 5, 2006 / Posted by: Shige Abe
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Exotic Earths
Collaborators from NAI’s Teams at NASA Goddard Space Flight Center, University of Colorado, Boulder, and Penn State as well as the former Virtual Planetary Lab Team have a paper this week in Science discussing the possible formation of “Exotic Earths.” Their models have simulated terrestrial planet growth during and after inward giant planet migration. Their results cause them to speculate that more than a third of the known systems of giant planets may harbor Earth-like planets.
September 7, 2006 / Posted by: Shige Abe
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Interstellar Chemistry Record
Researchers at NAI’s Carnegie Institution of Washington Team published this week in Science their new study of the interstellar chemistry record in both meteorites and interplanetary dust particles. They show that isotopic compositions in meteories meet and exceed those in found in IDP’s, demonstrating the capability of both to preserve primitive organics.
May 8, 2006 / Posted by: Shige Abe
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Habitable Conditions on the Early Earth
Direct information concerning the first 500 million years of Earth history – the Hadean Eon – is very limited, since practically no crustal rocks from that time have survived. We do know that the Earth collided much more frequently than it does today with asteroids and comets, as witnessed by the heavily cratered highlands of the Moon. Astronomers also tell us that the Sun was about 30 percent fainter then, so that the Earth may have been cold, unless there was a large greenhouse effect to trap the Sun’s heat and raise surface temperatures above the freezing point. Also of special interest is the apparent fact that life arose on Earth either during or shortly after the Hadean Eon.
January 23, 2006 / Posted by: Shige Abe
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Microbial Sulfur Disproportionation and Accelerated Oxygenation at Earth's Surface
Researchers from NAI’s Carnegie Institution of Washington Lead Team published a study in this week’s Science using high-precision measurements of a rare sulfur isotope, 33S, to establish that microbial sulfur disproportionation was in place almost half a billion years earlier than previously thought. This could imply that Earth’s surface may have become progressively more oxygenated during the middle Proterozoic.
December 6, 2005 / Posted by: Shige Abe
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The Origin of Planetary Impactors in the Inner Solar System
Scientists from NAI’s University of Arizona and University of Washington Lead Teams recently published a paper in Science concerning this history of the Solar System. Their paper looks at differences in the size distrubutions of asteroid populations during and after the heavy bombardment period ~ 3.8 billion years ago.
October 12, 2005 / Posted by: Shige Abe
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Digging in the Dirt on Mars
The following report is based on a short paper “The Enigma of the Martian Soil” by Amos Banin of the NAI SETI Institute Team, published in Science.
August 28, 2005 / Posted by: Shige Abe
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The Enigma of the Martian Soil
Amos Banin from NAI’s SETI Institute Team discusses the state of knowledge about the Martian soil in this week’s Science “Perspectives.” He looks specifically at information gained from past missions, and the role water processing may have played in soil formation.
August 4, 2005 / Posted by: Shige Abe
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End of Permian Extinction Theory Draws Technical Comments
Charles Marshall of NAI’s former Harvard University team published in this week’s Science his commentary on what he calls NAI Principal Investigator Peter Ward’s “groundbreaking” paper from January 2005. The comments are accompanied by a response from Ward et al.
June 9, 2005 / Posted by: Shige Abe
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