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GEODYNAMICS BRANCH SCIENCE HIGHLIGHTS - APRIL 2003 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. Herbert.V.Frey@nasa.gov GEODYNAMICS BRANCH SCIENCE HIGHLIGHTS - APRIL 2003 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 921, firstname.lastname@example.org 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. email@example.com GEODYNAMICS BRANCH SCIENCE HIGHLIGHTS - APRIL 2003 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 (LOD). 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, David.P.Rubincam@nasa.gov episodic change in length of day.
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