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Fwd = [back2moon] A Moonwalker's Perspective 30 Years Later:

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  • Frits Westra
    Forwarded by: fwestra@hetnet.nl (Frits Westra) Originally from: Reynold DeMarco Jr. Original Subject: [back2moon] A
    Message 1 of 1 , Oct 31, 2002
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      Forwarded by: fwestra@... (Frits Westra)
      Originally from: "Reynold DeMarco Jr." <reynold@...>
      Original Subject: [back2moon] A Moonwalker's Perspective 30 Years Later:
      Original Date: Wed, 30 Oct 2002 20:42:25 -0000

      ========================== Forwarded message begins ======================

      Geological Society of America
      Denver, Colorado

      Contact: Ann Cairns
      Phone: 303-357-1056; Fax: 303-357-1074
      acairns@...

      FOR IMMEDIATE RELEASE: October 29, 2002

      GSA Release No. 02-46

      A Moonwalker's Perspective 30 Years Later: Harrison Schmitt
      to Offer "Shocking Revelations" at GSA Annual Meeting

      The date was December 11, 1972, and the occasion was the
      last Apollo mission to the Moon. Apollo 17 astronaut
      Harrison Schmitt landed in the Valley of Taurus-Littrow,
      the only scientist and the last of 12 men to step onto the
      lunar surface. Standing in a brilliantly sun-lit valley
      deeper than the Grand Canyon and gazing at a nearly full
      Earth in a deep black sky, Schmitt's questions about the
      origins of the Moon and terrestrial planets and their
      subsequent history took on very personal significance.

      Today, geoscientist Schmitt, literally one in six billion
      human beings to combine science with actual lunar
      exploration, continues to ponder those big questions.
      He'll share some of the results of his synthesis of the
      research of many others on Tuesday, Oct. 29, at the
      annual meeting of the Geological Society of America in
      Denver, CO. At the GSA Planetary Geology division's
      Gilbert Lecture and Award Ceremony, Schmitt will discuss
      "A Lunar Field Geologist's Perspective 30 Years Later:
      Shocking Revelations about the Moon, Mars, and Earth."

      Shocking? The orange "soil" or pyroclastic glass that
      Schmitt found on the Moon, for example, continues to
      provide clues about the origin of the Moon. In Schmitt's
      view, it also reveals why the prevailing Giant Impact
      hypothesis of the Moon's origins doesn't work.

      "The major problem with this hypothesis," says Schmitt,
      "is that the interior of the Moon is not cooperating. Most
      importantly, the lower lunar mantle, based on analyses of
      the Apollo 17 orange pyroclastic glass, has a chondritic,
      that is, primordial elemental and isotopic imprint. This
      primordial imprint would have disappeared or have been
      significantly modified if the mantles of the Earth and
      the impactor had already formed as required by the
      current Giant Impact hypothesis.

      According to Schmitt, "If the Giant Impact hypothesis
      is not compatible with this evidence, alternatives to
      it should be considered, including capture of a small,
      independent planet from a solar orbit near that of the
      Earth's."

      Similarly, many scientists agree that the Moon's 50 or
      so basins greater than 300km in diameter, as well as
      most other ancient lunar craters, were formed at about
      the same time by an apparent "cataclysm" 3.9 billion
      years ago. According to Schmitt, "the primary argument
      against this hypothesis is found in the sampling sites
      for Apollo and lunar meteorite samples of impact-created
      glass for which formation ages have been determined.
      These samples have come largely from the surface of the
      Moon most affected by the 14 youngest large basin-forming
      impacts and debris thrown from them. These 14 youngest
      impacts are, indeed, 3.9-3.8 billion years old based on
      the dating of Apollo samples. A variety of volcanic and
      impact evidence indicates that it is highly unlikely that
      all the 35 or more older impact basins formed during the
      same interval.

      "One of the most exciting aspects of studying lunar
      origin and evolution is applying that understanding to
      the early Earth and Mars," says Schmitt. "And herein
      lies a 'shocking' revelation about the possible origin
      of Earth's first continents."

      The 2500km diameter basin on the far-side of the Moon,
      known as South Pole-Aitken, records an impact of an
      extraordinarily energetic object near the end of the
      period of smaller scale saturation cratering that followed
      the solidification of the lunar crust. South Pole-Aitken
      is just the most obvious manifestation of possibly three
      or four other such huge early impacts, including the
      3200km diameter front-side basin called Procellarum.

      Schmitt estimates that the Procellarum basin formed at
      about 4.3 b.y and South Pole-Aitken at about 4.2 b.y. If
      these formation ages are in the ballpark, they suggest
      an explanation for detrital zircon (ZrSiO4) crystals of
      about the same ages in very old sedimentary rocks on
      Earth. Early impacts of the scale of South Pole-Aitken
      and Procellarum, occurring in water-rich environments
      such as the Earth and Mars, would create thick sheets
      of impact generated rock melt on a continental scale. As
      these magma sheets crystallized, zirconium concentrations
      may have reached levels that produced the very old zircons.

      And what about Mars? Schmitt also suggests that there is
      evidence for and reason to believe that Mars had both
      early (older than 4.2 billion years) and late (younger
      than 3.8 billion years) oceans due to separate periods
      of intense volcanic eruptions that included abundant
      water. The shores of these two oceans appear to have
      been identified in the data returned by the Mars Surveyor
      spacecraft now in orbit around that planet. Further, he
      speculates that the most stable ecological niche for
      Martian life has been the boundary between the subsurface
      water ice zone and liquid water expected beneath that
      zone. If simple, one cell life forms evolved on Mars in
      parallel with their evolution on the Earth prior to 3.8
      billion years ago, they may have adapted to survive in
      this global niche as the surface of Mars became hostile
      to any life.

      "Extrapolating what we now know about the Moon and
      applying it to Earth, Venus, Mars, and Mercury -- the
      terrestrial planets -- is one of the primary scientific
      returns of lunar research. But looking ahead, the Moon
      will also mature our thinking about the gas giants and
      other parts of the solar system," says Schmitt. For
      example, whether as a result of a cataclysm or not,
      where did the objects originate that created the 50
      or more large basins on the Moon? He'll continue to
      contribute to that work, this time with his feet firmly
      planted on Earth, while developing a business rationale
      to return to the Moon for its energy resources.

      "A Lunar Field Geologist's Perspective 30 Years Later:
      Shocking Revelations about the Moon, Mars, and Earth"

      Harrison H. Schmitt
      Gilbert Lecture – GSA Planetary Geology Division
      Tuesday, Oct. 29, 6:00-7:00 p.m.

      CONTACT INFORMATION

      During the GSA Annual Meeting, Oct. 27-30, contact Christa
      Stratton at the GSA Newsroom in the Colorado Convention
      Center, Denver, Colorado, for assistance and to arrange for
      interviews: (303) 228-8565.

      Post-meeting contact information:

      Harrison H. Schmitt
      schmitt@...
      505-823-2616

      Ann Cairns
      Director of Communications
      Geological Society of America
      acairns@...
      303-357-1056


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