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Astrobiology, 2003
A major goal of NASA's Origins Program is to find habitable planets around other stars and determine which might harbor life. Determining whether or not an extrasolar planet harbors life requires an understanding of what spectral features (i.e., biosignatures) might result from life's presence.
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A major goal of NASA's Origins Program is to find habitable planets around other stars and determine which might harbor life. Determining whether or not an extrasolar planet harbors life requires an understanding of what spectral features (i.e., biosignatures) might result from life's presence.
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2007
The Earth is so far the only place in the Universe where life is known to exist. Is the Earth special, or are there other places both in our own solar system and beyond where life may have originated and either became extinct or still exists today? Hopefully, in the not to distant future we may find out.
Oliver Botta, Jeffrey L. Bada
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The Earth is so far the only place in the Universe where life is known to exist. Is the Earth special, or are there other places both in our own solar system and beyond where life may have originated and either became extinct or still exists today? Hopefully, in the not to distant future we may find out.
Oliver Botta, Jeffrey L. Bada
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Flash Heating on the Early Earth
Origins of life and evolution of the biosphere, 1999It has been suggested that very large impact events (approximately 500 km diameter impactors) sterilized the surface of the young Earth by producing enough rock vapor to boil the oceans. Here, we consider surface heating due to smaller impactors, and demonstrate that surface temperatures conductive to organic synthesis resulted. In particular, we focus
J R, Lyons, A R, Vasavada
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Nature Geoscience, 2013
Some mantle plumes are enriched in 3He, but the source of this primordial isotope is unclear. The partitioning behaviour of helium between silicate and iron melts—as determined by experiments—suggests that sufficient helium may have been incorporated into the core when the Earth differentiated to explain the anomalous leakage at the Earth’s surface.
Bouhifd, Mohamed Ali +3 more
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Some mantle plumes are enriched in 3He, but the source of this primordial isotope is unclear. The partitioning behaviour of helium between silicate and iron melts—as determined by experiments—suggests that sufficient helium may have been incorporated into the core when the Earth differentiated to explain the anomalous leakage at the Earth’s surface.
Bouhifd, Mohamed Ali +3 more
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Early differentiation of the Earth and the Moon
Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, 2008We examine the implications of new182W and142Nd data for Mars and the Moon for the early evolution of the Earth. The similarity of182W in the terrestrial and lunar mantles and their apparently differing Hf/W ratios indicate that the Moon-forming giant impact most probably took place more than 60 Ma after the formation of calcium-aluminium-rich ...
Bourdon, Bernard +3 more
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2015
Contributors Preface Acknowledgements 1. Timing of nebula processes which shaped the precursors of the terrestrial planets Marc Chaussidon and Ming-Chang Liu 2. The Earth s building blocks Frederic Moynier and Bruce Fegley, Jr. 3. Earth and Terrestrial Planet Formation Seth A. Jacobson, Kevin J. Walsh 4.
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Contributors Preface Acknowledgements 1. Timing of nebula processes which shaped the precursors of the terrestrial planets Marc Chaussidon and Ming-Chang Liu 2. The Earth s building blocks Frederic Moynier and Bruce Fegley, Jr. 3. Earth and Terrestrial Planet Formation Seth A. Jacobson, Kevin J. Walsh 4.
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2021
In the previous chapters, we have outlined the journey of our realization of the expanding spatial size of the Universe. In this chapter, we will discuss how our concept of temporal history has also been expanding. Human history is based on generational oral and written accounting of events of the past.
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In the previous chapters, we have outlined the journey of our realization of the expanding spatial size of the Universe. In this chapter, we will discuss how our concept of temporal history has also been expanding. Human history is based on generational oral and written accounting of events of the past.
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Science, 1997
Life on Earth is thought to have started about 4 billion years ago, yet the sun's luminosity at that stage of its evolution would have been 25 to 30% lower than today. This primordial solar luminosity would have been insufficient to heat the Earth enough to allow water to be in its liquid phase and so enable the formation of life, a dilemma that has ...
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Life on Earth is thought to have started about 4 billion years ago, yet the sun's luminosity at that stage of its evolution would have been 25 to 30% lower than today. This primordial solar luminosity would have been insufficient to heat the Earth enough to allow water to be in its liquid phase and so enable the formation of life, a dilemma that has ...
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Impact Processes on the Early Earth
Elements, 2006At the beginning of the solar system, impacts and collisions were dominant processes. After an early collision that may have led to the formation of the Moon, both Earth and Moon suffered intense post-accretionary bombardment between about 4.5 and 3.9 billion years before present.
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Geology, 2002
No known rocks have survived from the first 500 m.y. of Earth history, but studies of single zircons suggest that some continental crust formed as early as 4.4 Ga, 160 m.y. after accretion of the Earth, and that surface temperatures were low enough for liquid water. Surface temperatures are inferred from high d 18 O values of zircons. The range of d 18
John W. Valley +3 more
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No known rocks have survived from the first 500 m.y. of Earth history, but studies of single zircons suggest that some continental crust formed as early as 4.4 Ga, 160 m.y. after accretion of the Earth, and that surface temperatures were low enough for liquid water. Surface temperatures are inferred from high d 18 O values of zircons. The range of d 18
John W. Valley +3 more
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