archive: SETI [ASTRO] Lecture On The Impact Of Comets And Asteroids Upon The

SETI [ASTRO] Lecture On The Impact Of Comets And Asteroids Upon The

Larry Klaes ( )
Mon, 03 May 1999 11:10:23 -0400

>X-Authentication-Warning: majordom set sender
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>Date: Sat, 1 May 1999 2:19:51 GMT
>From: Ron Baalke <>
>Subject: [ASTRO] Lecture On The Impact Of Comets And Asteroids Upon The Earth
>Reply-To: Ron Baalke <>
>By Donald K. Yeomans
>Supervisor, Solar System Dynamics Group
>Jet Propulsion Laboratory
>Monday, May 17, 1999
>7:30 p.m. at
> Comets and asteroids have been receiving bad press of late.
>In two recent movies, they have been portrayed as Earth threatening
>villains. While comets and asteroids do smack into the Earth from
>time to time, it is also likely that they helped deliver the water
>and carbon-based molecules to the early Earth, thus providing the
>building blocks for the formation of life. Subsequent collisions may
>have punctuated life's evolutionary cycles allowing only the most
>adaptable species to evolve further. We mammals may owe our
>preeminent position atop the Earth's food chain to a collision some
>65 million years ago that wiped out most of our competition -
>including the dinosaurs.
> Ironically, the same comets and asteroids that can most
>closely approach the Earth are also the most accessible in terms of
>exploiting their vast supplies of water and metals. Comets and
>asteroids could easily supply the raw materials necessary for
>colonizing the inner solar system in the next century. In addition to
>the utility of assessing their potential as future threats and
>resources, there are compelling scientific reasons for studying these
>primitive leftovers from the solar system formation process.
>Knowledge of their compositions and structures will provide important
>clues to the conditions and chemical mix from which the planets
>formed some 4.6 billion years ago. The nature and chemical
>composition of these enigmatic objects should soon become clear as
>spacecraft missions closely study a dozen comets and asteroids in the
>next 13 years.
> At the Jet Propulsion Laboratory, Don Yeomans is a Senior
>Research Scientist and Supervisor for the Solar System Dynamics
>Group. Dr. Yeomans is the Project Scientist for the MUSES-CN mission
>to explore the surface of a near-Earth asteroid and Radio Science
>Team Chief for the Near-Earth Asteroid Rendezvous (NEAR) mission. He
>is the current Chairman for the Division of Planetary Sciences and
>has recently been appointed manager of NASA's Near-Earth Object
>Program Office. His research work is focused upon the physical and
>dynamical modeling of comets and asteroids. He has been active in
>providing the observing community and flight projects with position
>predictions for hundreds of comets and asteroids including those that
>have been, or will be, mission targets. In refining the motions of
>comets and asteroids, he has used data types as diverse as recent
>radar measurements, Hipparcos-based astrometry, and ancient Chinese
>observations. Don has received 10 NASA Achievement awards including
>an Exceptional Service Medal in 1986. He has published three books
>and over 100 technical papers. Asteroid 2956 was renamed 2956 YEOMANS
>to honor his professional achievements.
> Friends Of The Observatory (FOTO) is the non-profit support
>group for Griffith Observatory. Currently, one of FOTO's primary
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>so that it continues to provide the nearly 2 million visitors and
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>recognizable icon of Los Angeles.
>Admission: $2 for FOTO members, $5 for non-members; tickets are
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>Griffith Observatory Griffith phone: (323) 664-1181
>2800 East Observatory Road Griffith fax: (323) 663-4323
>Los Angeles, California 90027 USA