SETI public: FW: NASA SCIENTISTS CONFIRM LIQUID WATER ON EARLY EARTH

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>From: "NASANEWS_at_mail.arc.nasa.gov" <nasanews_at_mail.arc.nasa.gov>
>To: ames-releases_at_lists.arc.nasa.gov
>Subject: NASA SCIENTISTS CONFIRM LIQUID WATER ON EARLY EARTH
>Date: Fri, 3 Jun 2005 10:12:03 -0700
>
>
>
>Nicholas A. Veronico/Michael Mewhinney June 3, 2005
>Ames Research Center, Moffett Field, Calif,
>Phone: 650/604-1939, 650/604-9000
>E-mail: nveronico_at_mail.arc.nasa.gov
>
>NEWS RELEASE: 05-35
>
>NASA SCIENTISTS CONFIRM LIQUID WATER ON EARLY EARTH
>
>Research funded partly by NASA has confirmed the existence of liquid water
>on the Earth's surface more than 4 billion years ago.
>
>Scientists have found that the Earth had formed patterns of crust
>formation, erosion and sediment recycling as early as 4.35 billion years
>ago. Their findings came during a study of zircon crystals formed during
>the earliest period of Earth's history, the Hadean Eon (4.5 billion to 4.0
>billion years ago).
>
>"NASA is interested in how early the Earth had abundant liquid water. If
>oceans form early in a planet's history, then so can life," said Carl
>Pilcher, senior scientist for astrobiology at NASA Headquarters,
>Washington. "Learning how early oceans formed on Earth will help us
>understand where else oceans and perhaps even life may have formed in this
>solar system and in planetary systems around other stars."
>
>"This work provides direct evidence that the Earth was probably habitable
>within a hundred million years of its formation," said Bruce Runnegar,
>director of the NASA Astrobiology Institute (NAI) at NASA Ames Research
>Center, Moffett Field, Calif., which provided some of the study's funding.
>
>Published in the May 6, 2005, edition of Science, the research was
>conducted by T. Mark Harrison of the Research School of Earth Sciences,
>Australian National University, Canberra and the University of California,
>Los Angeles; and E. Bruce Watson of the Department of Earth & Environmental
>Sciences at Rensselaer Polytechnic Institute, Troy, N.Y. Field research was
>completed in Western Australia's Jack Hills, which preserve a record of the
>Hadean Eon.
>
>Watson and Harrison devised a new method of determining the temperatures at
>which the rocks formed. The team extracted and examined more than 50,000
>zircons, crystals about the width of a human hair, which have been exposed
>through natural erosion in the Jack Hills. From the 50,000 zircons, only a
>couple of hundred were older than 4.2 billion years. Measuring the
>temperature at which the rocks melt gives an indication of the conditions
>in which they formed.
>
>"Rocks formed as a result of the thermal energy from meteorite impacts
>would be bone dry and melt at greater than 900 degrees Celsius," said
>Harrison. "In contrast, our study has found that Hadean rocks melted at a
>consistent average temperature of 690 degrees Celsius. Water, which is a
>very powerful catalyst, must have been present in very large amounts for
>rocks to melt at such a relatively low temperature."
>
>This discovery supports the proposal by Harrison's group four years earlier
>that a heavy oxygen isotope signature in the Hadean zircons is evidence for
>liquid water at or near the Earth's surface by 4.3 billion years ago.
>
>The NAI, founded in 1997, is a partnership between NASA, 16 major U.S.
>teams and five international consortia. NAI's goal is to promote, conduct
>and lead integrated multidisciplinary astrobiology research and to train a
>new generation of astrobiology researchers.
>
>For more information about the NAI on the Internet, visit:
>
>http://nai.arc.nasa.gov
>
>For information about NASA and agency programs on the Internet, visit:
>
>http://www.nasa.gov
>
>-end-
>
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>

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