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Planetology Seminar Series |
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PLANETOLOGY SEMINAR (ESS 286C)
Spring Quarter 2007
Earth & Space Sciences, UCLA
Thursdays at 12 noon, 4677 Geology Building
All Welcome
Professor Gerald Schubert (schubert@ucla.edu), Organizer
| Date |
Speaker | Affiliation | Seminar Title |
| April 12 |
Colleen Milbury |
ESS/UCLA |
Regional Correlations of Gravity and Magnetic Anomalies on Mars |
| In this talk I will discuss an apparent correlation of the gravity and magnetic anomalies along Mars' eastern dichotomy boundary. The spatial scale of the gravity and magnetic anomalies are similar, and the ratio of the amplitudes remains roughly constant, although increases eastward. This may suggest that the same process may be responsible for the formation of the anomaly sources. I will give results for the joint analysis of gravity and magnetic field data for the study areas. |
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| April 19 |
Jennifer Palgula |
ESS/UCLA |
Fluid Flow and Aqueous Alteration in Carbonaceous Chondrite Parent Bodies |
| Carbonaceous chondrites (CCs) are among the most primitive materials in the Solar System; thus, they provide an important source of information on processes and conditions during early solar system evolution. However, most carbonaceous chondrites have been processed and are not pristine relics. In particular, it is clear that CI and CM chondrites experienced low-temperature aqueous alteration. This alteration may overprint the early Solar System record contained in these chondrites. The differences between the CI and CM groups have often been attributed to processing on distinctive parent bodies. However, there is evidence that more than one type of CC could arise from the same parent body. Numerical modeling of chemically reactive hydrothermal circulations further supports heterogeneous parent body alteration. I will review the evidence for fluid flow and the formation of alteration zones in CC parent bodies. |
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| April 26 |
Robert Pappalardo |
Planetary Science and Life Detection Section
Jet Propulsion Laboratory, California Institute of Technology |
Ices and Oceans in the Outer Solar System |
| Since the early 1970s, planetary scientists have used theoretical and observational arguments to deliberate the existence of surface and interior oceans on and within the outer solar system's icy planetary bodies. Consideration of the four "ingredients" necessary for development of life (water, chemical energy, biogenic elements, and stable environment) point to Europa as a key target in the search for life in our solar system. A combination of radiogenic and tidal heating could allow oceans to persist over long time scales, especially if low melting-point "antifreeze" (e.g. ammonia) is present. Ice convection (where it occurs) tends to freeze an interior ocean, but there is a complex interplay among ice rheology, ice shell thickness, tidal heating, and heat transport mechanisms. Galileo magnetometer observations suggest oceans within all three icy Galilean satellites of Jupiter. The probable oceans of Callisto and Ganymede are sandwiched between >100 km thick Ice I above and denser ice polymorphs below. In contrast, Europa's ocean is capped by a relatively thin and tidally heated ice shell. Geological evidence affirms recent surface-ocean exchange at Europa; moreover, its ocean is probably in direct contact with an underlying rocky mantle, facilitating direct deposition of any hydrothermal chemical energy. At Saturn's moon Titan, gully systems argue for hydrocarbon rain and radar imaging suggests liquid hydrocarbons on the surface; moreover, Titan plausibly contains an interior water-ammonia ocean. Tiny Enceladus displays geyser-like activity, with water vapor rising from prominent fractures in the warm and tectonically deformed south polar terrain. Activity at Enceladus may be driven by shear heating along fractures, causing sublimation and redeposition of water vapor, with significant tidal deformation permitted by a deep subsurface ocean. Triton is too cold for a once-hypothesized open ocean of nitrogen, but past tidal and current radiogenic heating combine to permit an interior ocean today. The interior oceans of icy bodies may be the most common habitats for life in the universe, and we would be remiss not to explore them. |
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| May 3 |
Eric King |
ESS/UCLA |
Simulating Core Turbulence in the Laboratory |
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| May 10 |
Dr. William B. Moore |
ESS/UCLA |
Convective Boundary Layers: Parameterized, Numerical, and Laboratory |
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| May 17 |
Britney Schmidt |
ESS/UCLA |
From Big Rocks to Little Planets
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| The material in the asteroid belt presents us with a snapshot of the earliest epoch of the solar system's formation. The bodies in this region vary from small, pristine samples of the accreting disk to larger thermally evolved protoplanets whose accretionary growth was terminated by the gravitational pumping of the gas giants. They provide a link between early nebular and planetary processes. Exploring the full spectrum of bodies in the asteroid belt is vital to the understanding of the early solar system, but spacecraft will visit only a handful. Thus, telescopic observations play an important role in interpreting the asteroids. Recent observations have revolutionized what we know about asteroids: they are more than simple space rocks, they are evolved, dynamic bodies with important information about solar system origins. The largest asteroids represent objects that grew massive enough to undergo varying degrees of compositional differentiation. 1 Ceres, 2 Pallas and 4 Vesta are the largest of the asteroids, each of them unique. Considerable opportunity remains for observing these objects, particularly Pallas. I will highlight the current state of knowledge for these objects, and the strategies we have used to plan upcoming observations with HST of Vesta (May 14 &16), Pallas (September), and Ceres (October). Ceres and Vesta will be visited by the Dawn spacecraft, now scheduled for a June 30 launch. For large asteroids, remote sensing is complimentary to spacecraft studies, whereas for the smallest bodies, remote sensing is often the only tool available. Often, ground based campaigns are preparatory for spacecraft visits, but in 2002 the reverse occurred. A fortuitous flyby of the 6km 5535 Annefrank by the Stardust spacecraft provoked a flurry of telescope observations to understand this asteroid. I will discuss the light curve and discovery of the rotation period of Annefrank from Table Mountain observations and how these measurements can help us interpret the Stardust data. Clearly the asteroids are diverse objects with unique histories, the study of which provides context for the formation of the solar system. |
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| May 24 |
Krista Soderlund |
ESS/UCLA |
Modeling Deep Convection on the Ice Giants |
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| May 31 |
Dr. John Anderson |
Global Aerospace Corporation |
Saturn's Gravity Field, Internal Rotation, and Interior Structure |
| The orbiting Cassini spacecraft can be used as a sensitive probe of Saturn's gravity field, which is now known far better than previous fields inferred from Pioneer and Voyager spacecraft flybys. However, Cassini magnetic-field data and measurements of Saturn kilometric radiation (SKR) yield the surprising result that Saturn's internal rotation period is unknown, though it must be less than 10^h 39^m 22^s. By using Cassini gravity data, along with Pioneer and Voyager radio occultation and wind data, and minimizing the wind-induced dynamic heights of the 100 mbar isosurface with respect to a Saturn reference geoid, we obtain a best-fit reference-geoid rotation period of 10^h 32^m 30^s ± 17s. We suggest that this rotation period, which is consistent with the upper bound from all available magnetic and SKR data, is the period of rotation of Saturn's deep interior. The effects of this more rapidly spinning reference geoid on atmospheric dynamics is profound. The eastern wind speeds on the equator are greatly reduced from what was previously thought, corresponding to a reduced equatorial bulge from 122 km to 10 km, and the winds at higher latitudes flow both east and west, as on Jupiter. The internal structure of the rapidly rotating Saturn model has a molecular to metallic hydrogen transition about halfway to the planet's center. Improved equation of state (EOS) data are needed to constrain the size of an ice/rock/metal core at the center of Saturn. |
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| June 7 |
Dr. Leslie Tamppari |
Jet Propulsion Laboratory |
The Phoenix Mission |
| The Phoenix Mars lander mission is the first mission in NASA's Mars Scout Program. A collaboration between the University of Arizona, Lockheed Martin, and JPL, the Phoenix mission will launch on August 3, 2007 and land in the high northern latitudes on Mars on May 25, 2008. The mission's goals are to study the history and current state if water and to understand the potential habitability of the landing site. The mission goals, instruments, and landing site selection will be discussed. |
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