LPI Seminar Series
Effective January 1, 2011, LPI seminars will be held on Fridays.
LPI seminars are held from 3:30–4:30 p.m. in the Lecture Hall at USRA, 3600 Bay Area Boulevard, Houston, Texas. Refreshments are served at 4:30 p.m. For more information, please contact Yann Sonzogni (phone: 281-486-2199; e-mail:email@example.com) or Debra Hurwitz (phone: 281-486-2116; e-mail: firstname.lastname@example.org). A map of the Clear Lake area (PDF format) is available here. The Acrobat Reader 8.0 is available from Adobe. This schedule is subject to revision.
- Friday, January 10, 2014 - Lecture Hall, 3:30 PM
Francesca Scipioni - Italian Space Agency
Spectroscopic Classification and Investigation of Terrain Units of Saturn's Icy Moons
In my PhD work, I have focused on the study of Saturn's icy satellites Dione and Rhea using data acquired in the infrared spectral range by the Cassini/VIMS imaging spectrometer. The surfaces of the main Saturnian icy moons are composed primarily by water ice, with a minor percentage of non-water-ice material whose composition is still debated and whose distribution is not uniform across the satellites’ surface. The differences in contaminants’ composition, water-ice abundance and regolith grain size are revealed by variations in spectral profiles, which are bounded both to exogenic (micrometeoroids and particles coming from rings or interplanetary dust) and endogenic (cry-volcanism, tectonic activity) processes. The only way to discern between them and, in turn, to understand how each satellite evolved, is to investigate the distribution of contaminants and water-ice on the moons’ surfaces. In order to identify different terrain units on the two satellites’ surface we applied the Spectral Angle Mapper (SAM) classification technique to Dione’s and Rhea’s hyperspectral images acquired by VIMS in the infrared range. On a relatively limited portion of the surface of Dione and Rhea we first identified nine and eight spectral endmembers respectively, corresponding to as many terrain units, which mostly distinguish for water ice abundance and ice grain size. We then used these endmembers in SAM to achieve a comprehensive classification of the entire surface. The analysis of the infrared spectra returned by VIMS shows that different regions of Dione and Rhea have variations in water ice bands depths, in average ice grain size, and in the concentration of contaminants, such as CO2 and hydrocarbons, which are clearly connected to morphological and geological structures. Generally, the spectral units that classify optically dark terrains are those showing suppressed water ice bands, a finer ice grain size and a higher concentration of carbon dioxide. Conversely, spectral units labeling brighter regions have deeper water ice absorption bands, higher albedo and a smaller concentration of contaminants. Finally, we performed a comparison between Rhea and Dione, to highlight different magnitudes of space weathering effects in the icy satellites as a function of the distance.
- Friday, January 24, 2014 - Lecture Hall, 3:30 PM
Robert Herrick, University of Alaska Fairbanks
- Friday, January 31, 2014 - Lecture Hall, 3:30 PM
Peter Isaacson, Hawaii Institute of Geophysics and Planetology
- Friday, April 11, 2014 - Lecture Hall, 3:30 PM
Karl Leon Mitchell, Jet Propulsion Laboratory, California Institute of Technology
Volcanism in the Solar System
Dr Karl Mitchell of Jet Propulsion Laboratory will give a tour of volcanoes in the solar system, explaining their dynamics and the roles of various modulating influences, including environment, chemistry and orbital dynamics on eruption styles. Limitations in our current understanding will be discussed, with an emphasis on the difficulty in relating remotely-sensed observations to conditions at the time of activity.