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   Geodynamics Branch Personnel Present Papers at Houston Meeting
   Bills, Frey, Mest, Roark and Sakimoto Author and Co-Author Papers on Mars, Jupiter
   Satellites, and Educational-Outreach at 34th Lunar and Planetary Science Conference
Bruce Bills gave an oral presentation                         Jim Roark presented the poster by
on “Spatial and Temporal Patterns of                          Keller, Roark, Sakimoto, Stockman
Tidal Dissipation in Synchronous                              and Frey on “3-Dimensional Topo-
Satellites” in the Io and Beyond ses-                         graphic Models for the Classroom” in
sion, and was co-author on a paper                            the Educational and Public Outreach
by Comstack on “A Solar System                                poster session. This work is part of
Survey of Forced Librations in long-                          a recently awarded DDF which was
itude” in the Venus poster session.                           described in the 921 December 2002
                                                              Science Highlight.
                 Herb Frey gave “Large Diameter
                 Visible and Buried Basins on Mars:                            Susan Sakimoto did not attend,
                 Implications for Age of Highlands      OBSERVED VERSUS PREDICTED BIOMASS
                                                                      but her paper with co-authors
                 and (Buried) Lowlands and Turn-                                 Gregg, Hughes and Chadwick on
                 Off of the Global Magnetic Field” in                            “Martian Plains Volcanism in
                 Mars Geophysics and Tectonics,                                  Syria Planum and Tempe Mareotis
                 which he co-chaired. In the Mars                                as Analogs to the Eastern Snake
                 Geologic Mapping posters Frey and                               River Plain, Idaho: Similarities
others (E. Frey, K. Tanaka, W. Hartmann) showed                                  and Possible Petrologic Contri-
“Evidence for Buried “Pre-Noachian” Crust Pre-                                   butions to Topography” in the
Dating the Oldest Observed Surface Units on Mars”.            Mars Volcanism session was presented by her co-
                                                              author Tracy Gregg. Sakimoto was also a co-author
Scott Mest, a PhD Graduate Student
                                                              on two papers, one by Chase “Thermal Modeling of
Research Program (GSRP) candidate
                                                              Permafrost Melt by Overlying Lava Flows with
at the University of Pittsburgh now
                                                              Applications to Flow-Associated Outflow Channel
resident in the Geodynamics Branch,
                                                              Volumes in the Cerberus Plains, Mars” and one by
showed a poster in Mars Geologic
                                                              Polit with Mitchell and Grosfils on “Geometric
Mapping on “Geology of the Crater
                                                              Properties of Possible Volcanoes in the South Polar
Millochau, Terra Tyrrhena Region of
                                                              region, Mars” as well as the Keller paper above.
Mars”, and was a co-author on the
Crown and others paper “Geomorphology of debris
Aprons in the Eastern Hellas Region of Mars” in the               Contact: Herb Frey, GSFC Code 921,
Mars Geology and Analog Studies session.                     
Spotlight: Stockman Gives Keynote Address at Millersville University
     Women in Mathematics and Science Conference Attracts Teachers and Students
                  Millersville University (PA), the Hazeltine family and Pfizer, Inc. sponsor an annual Glenna Hazeltine
                  Women in Mathematics and Science Conference. The purpose: to encourage young women in grades
                  7 through 12 to pursue a career in science and mathematics by giving them opportunities to meet a
                  variety of professional women role models who have successfully pursued such careers. This year
                  Stephanie Stockman was the keynote speaker for the 16th conference, held April 8 at the Millersville
                  University Campus is Millersville, PA. Her topic, “Adventures in Earth and Space Sciences at NASA”,
                  described her own career from part-time research and teaching to full-time geoscience education and
                  public outreach work. Stephanie works for SSAI and is a member of the Geodynamics Branch.

Stephanie Stockman is a structural geologist and geoscience educator. She began her career at NASA's Goddard
Space Flight Center in 1992 as a part time researcher, studying multi-ringed impact basins on Mars. During that
                                                                                  OBSERVED VERSUS PREDICTED               BIOMASS
time, she also taught Physical Geology and Introductory Chemistry at Montgomery College in Takoma Park,
Maryland. By 1997, Stephanie was looking for new ways to share the work of scientists and engineers at NASA as
the fulltime Education and Public Outreach (E/PO) coordinator for the Laboratory for Terrestrial Physics at
Goddard. She now develops E/PO programs for NASA satellite missions. She is the E/PO lead for MESSENGER, a
Discovery Mission to Mercury that launches in 2004. She coordinates the E/PO efforts of EOS Aura (an
atmospheric chemistry satellite) and the Landsat 7 (land remote sensing satellite) Project Science Office. In
addition, Stephanie is the Education Co-investigator for the GLOBE Soils Characterization Investigation and the
GLOBE Aerosols Investigation.

Stephanie has a BS in Geology from Towson State University, extensive graduate work in structural geology and
tectonics and a M.Ed. in Geoscience Education from the University of Maryland.

ANOTHER KEYNOTE ADDRESS: Jacob Yates, also an SSAI employee                                    Contact: Stephanie Stockman, GSFC Code
in the Geodynamics Branch, will be the keynote speaker at the State of
Maine’s Space Day on May 1. He will talk about Earth observation imagery
and visit several of the classrooms participating in EarthKAM, the ISS                           Contact: Jacob Yates, GSFC Code 921,
student involvement program described in February’s Science Highlight.                      
   Rubincam Paper May Explain 1000 Year Changes in Earth Rotation
“Lava Lamp” Model for Gravitational Core-Mantle Coupling to be Published in Journal of
                                Geophysical Research
It has been known for a long time that the Earth’s rate of rotation is changing. Post-
glacial rebound causes a small acceleration, but this is more than offset by lunar tidal
friction which is slowing down the Earth’s rotation and making the day longer. There
are historical records that suggest there is also some episodic or perhaps periodic
disturbance of the secular or long-term slowdown (see figure at right).
                   In a paper accepted for publication in the Journal of Geophysical
                   Research – Solid Earth, David Rubincam looked at whether                 There may be a 1000 year periodic
                   coupling between the liquid outer core and the mantle might be           change in the Earth’s Length of Day
                   responsible for the suspected 1000 year timescale. He studied the
                   effects that might result from the gravitational attraction between
                   density anomalies or “blobs” in the outer core and mantle. The
                   core anomalies, which would randomly come and go like the blobs
                   in a lava lamp (see figure at right), would cause time-variability in
                   the gravitational attraction between the outer core and mantle, in
                   turn producing torques which could affect and change the rotation
rate between the two parts of the Earth.
His analysis suggests that plausible density anomalies can produce the non-secular
acceleration, at least to the right order of magnitude, and on the timescales observed.
                                                                                           Like blobs in a lava lamp, density
Rubincam further suggests that, since the changing rotation of the mantle introduces       anomalies can form in the liquid outer
a torque on the rotation rate of the core, this mechanism may also account for the         core and in the mantle of the Earth.
                                                                                           Blobs in the core will change the
westward drift of the Earth’s magnetic field, which is observed and close to the rate      gravity field and cause torques on the
predicted by the model. Other effects produced by the coupling, such as changing the       mantle, changing the rate of rotation of
                                                                                           the Earth. The timescale for this
Earth’s tilt, appear to be small by comparison with other known causes.                    change is about 1000 years, and the
                                                                                           magnitude of the effect about what is
                                                                                           needed to explain what may be an
              Contact: Dave Rubincam, GSFC Code 921,             episodic change in length of day.

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