# Presentation: 118620

## GEODYNAMICS  BRANCH

***SCIENCE  HIGHLIGHTS  -  APRIL  2003***

**OBSERVED VERSUS PREDICTED BIOMASS**

_**Contact**_**:  Herb Frey, GSFC Code 921, Herbert.V.Frey@nasa.gov**

**Bruce Bills gave an oral presentation**
**on ****“Spatial and Temporal Patterns of**
**Tidal Dissipation in Synchronous**
**Satellites”**** in the *****Io and Beyond***** ses-**
**sion, and was co-author on a paper**
**by Comstack on ****“A Solar System**
**Survey of Forced Librations in long-**
**itude”**** in the *****Venus***** poster session.**
**                            ****Herb Frey gave ****“Large Diameter**
**                            ****Visible and Buried Basins on Mars:**
**                            ****Implications for Age of Highlands**
**                            ****and (Buried) Lowlands and Turn-**
**                            ****Off of the Global Magnetic Field****” in**
**                            *****Mars Geophysics and Tectonic*****s,**
**                            ****which he co-chaired.  In the *****Mars***
***                            ******Geologic Mapping***** posters Frey and**
**others (E. Frey, K. Tanaka, W. Hartmann) showed ****“Evidence for Buried “Pre-Noachian” Crust Pre-Dating the Oldest Observed Surface Units on Mars”.**
**Scott Mest, a PhD Graduate Student**
**Research Program (GSRP) candidate**
**at the University of Pittsburgh now**
**resident in the Geodynamics Branch,**
**showed a poster in *****Mars Geologic***
***Mapping***** on ****“Geology of the Crater**
**Millochau, Terra Tyrrhena Region of**
**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 *****Mars Geology and Analog Studies***** session.**

**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 34******th****** Lunar and Planetary Science Conference***

**Jim Roark presented the poster by**
**Keller, Roark, Sakimoto, Stockman**
**and Frey on ****“3-Dimensional Topo-**
**graphic Models for the Classroom”**** in**
**the *****Educational and Public Outreach***
**poster session.  This work is part of**
**a recently awarded DDF which was**
**described in the 921 December 2002**
**Science Highlight.**
**                               ****Susan Sakimoto did not attend, **
**                               ****but her paper with co-authors**
**                               ****Gregg, Hughes and Chadwick on**
**                               ****“****Martian Plains Volcanism in**
**                               ****Syria Planum and Tempe Mareotis**
**                               ****as Analogs to the Eastern Snake**
**                               ****River Plain, Idaho:  Similarities**
**                               ****and Possible Petrologic Contri-**
**                               ****butions to Topography”**** in the *****Mars Volcanism***** session was presented by her co-author Tracy Gregg.  Sakimoto was also a co-author on two papers, one  by Chase ****“Thermal Modeling of Permafrost Melt by Overlying Lava Flows with Applications to Flow-Associated Outflow Channel Volumes in the Cerberus Plains, Mars”**** and one by Polit with Mitchell and Grosfils on ****“Geometric Properties of Possible Volcanoes in the South Polar region, Mars”**** as well as the Keller paper above.**

## GEODYNAMICS  BRANCH

***SCIENCE  HIGHLIGHTS  -  APRIL  2003***

**OBSERVED VERSUS PREDICTED BIOMASS**

_**Contact**_**:  Stephanie Stockman, GSFC Code 921, stockman@core2.gsfc.nasa.gov**

**                            ****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 16****th**** 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.**

_**Spotlight**_**:  Stockman Gives Keynote Address at Millersville University**
***Women in Mathematics and Science Conference Attracts Teachers and Students***

**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 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 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 student involvement program described in February’s *****Science Highlight.***

_**Contact**_**:  Jacob Yates, GSFC Code 921, yates@core2.gsfc.nasa.gov**

## 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**
**                                 ****coupling between the liquid outer core and the mantle might be**
**                                 ****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.  Rubincam further suggests that, since the changing rotation of the mantle introduces a torque on the rotation rate of the core, this mechanism may also account for the westward drift of the Earth’s magnetic field, which is observed and close to the rate predicted by the model. Other effects produced by the coupling, such as changing the Earth’s tilt, appear to be small by**** ****comparison with other known causes.**

_**Contact**_**:  Dave Rubincam, GSFC Code 921, David.P.Rubincam@nasa.gov**

**There may be a 1000 year periodic change in the Earth’s Length of Day (LOD).**

**Like blobs in a lava lamp, density anomalies can form in the liquid outer core and in the mantle of the Earth.  Blobs in the core will change the gravity field and cause torques on the mantle, changing the rate of rotation of the Earth.  The timescale for this change is about 1000 years, and the magnitude of the effect about what is needed to explain what may be an episodic change in length of day.**