Dr. Georgiana Y. Kramer
My research interests include the chemistry and mineralogy of the Moon, asteroids, and other planetary surfaces through integrated sample and remote sensing data analysis. I study the physical and spectral effects of space weathering and impact gardening on the evolution of the lunar regolith. Understanding the effects from these processes improves the ability to map the composition of the pristine lithologies that make up the crust. The types and distribution of rocks that comprise the crust can be used to deduce mantle processes and planetary evolution.
My doctoral research focused on the petrogenesis and occurrence of the high-alumina mare basalts using geochemical and remote sensing techniques. I modeled the source petrology, parental melt composition, and petrogenesis of these basalts based on radiometric and major element data from the literature, and my analyses of the trace element abundances of 30 high-alumina basalts and 7 other lunar rock types relevant to the model. Using multispectral data from Clementine and Lunar Prospector I demonstrated that remote sensing data can be used to search for locate distinct lithologies.
I stress the importance of data integration, such as from returned samples, meteorites, and Earth-derived planetary-analog materials with various remote sensing instruments. These combined data sets can work synergistically to improve identiﬁcation of surface features and compositions, glean subsurface processes, and interpret the origin and evolution of a planetary body.
My research interests are driven by my desire to advance our understanding of the history and future of our solar system, contribute to its continued exploration, and promote its perception as an extension of our home to all people of Earth.
My work focuses on the use of spectroscopic data to determine the composition and model the evolution of the planetary crusts. I am also keenly interested in space weathering of planetary surfaces and its chemical and physical effects.
Mapping bedrock lithologies
Small Crater Rim and Ejecta Probing (SCREP)* is a program for determining the composition of pristine bedrock units in a multispectral remote sensing image by obtaining spectral data from pixels that represent the least contaminated portion of the unit exposed by a small, immature impact crater. The methodology borrows from established techniques in the planetary science community such as relative age dating using crater size-frequency distributions, impact crater degradation, and modeling material transport by impact gardening. These techniques, combined with knowledge of the local geology can be used to model endmember contribution to the regolith composition. The non-regolith endmembers are removed to obtain a more reﬁned bedrock unit composition.
Space weathering, space dew and the evolution of the regolith
- The agents of space weathering include particles ranging from meteorites to micrometeorites to solar-wind ions to high energy photons, all of which contribute to the formation, evolution, and characteristics of planetary regoliths. My interest is in studying the compositional and spectral effects that result from specific particles, and under what conditions do different space weathering agents dominate the regolith maturation process.
- Solar wind particles are almost certainly responsible for the formation and destruction of transient HOH and OH found outside of permanently shadowed regions of the Moon (space dew). I am interested in studying how space dew forms and which solar wind particles dominate the process.
- Lunar swirls are high-albedo, optically immature, and curvilinear surface features. Each swirl region is associated with a magnetic anomaly, which has been hypothesized to be shielding the swirls from the solar wind. They are ideal locations to compare the effects of space weathering because multispectral data shows speciﬁc and divergent spectral effects that are correlated with the shape of the swirls.
* SCREP is a freeware program, copyrighted under the terms of the GNU General Public License as published by the Free Software Foundation.
The second main emphasis of my research is using gravity and topography observations to study the structure of the crust and lithosphere of the terrestrial planets. I was a member of the science team for NASA’s GRAIL mission, which produced a very high resolution (~ 5 km/pixel) map of the Moon’s gravity field. I am using GRAIL gravity observations to understand the volcanic structure and subsurface plumbing of features such as the Gruithuisen Domes and the Marius Hills. I am also using gravity and topography observations to study the evolution of Mars, with a particular focus on large highland volcanos such as Syrtis Major and Apollinaris Mons. In support of these projects, I have measured the density and porosity of lunar and martian rocks using laser scanning and helium pycnometry in the Lunar Sample Laboratory and the Antarctic Meteorite Laboratory at NASA’s Johnson Space Center.
I am actively involved in a variety of science education programs. I have contributed to numerous summer teacher training workshops, including several that have been based at field sites in the western United States that serve as analogs for processes on the terrestrial planets (including the Channeled Scablands, the Columbia River flood basalts, Yellowstone, the Snake River Plains, the Cascade volcanos, Meteor Crater, and Mono Lake). I have also contributed to the development of a variety of education products designed for use in either formal classroom education or in informal education settings such as libraries.