Planetary Science Seminar - fall-2015

Oct. 1, 2015
noon - 12:50 p.m.
Geology 4677

Presented By:

• Journal Club -

Seminar Description coming soon.

Oct. 8, 2015
noon - 12:50 p.m.
Geology 4677

Presented By:

• Ryan Zeigler - NASA Johnson Space Center

Micro computed tomography (micro-CT) is now beginning to be utilized as a basic part of the curation process for meteorites and Apollo samples at Johnson Space Center. Initial scans have shown that we are able to readily identify diverse lithic clasts within polymict samples and use the scans as a guide to most efficiently subdivide the breccias to extract the lithic clasts, which will then made available to scientists for scientific studies. Moreover, we have been able to use the scans to identify the textures within lithic clasts, locate rare or sought after minerals within samples, and identify fractures or other weaknesses within the samples (which aids in extraction of clasts). Additionally, micro-CT can be used to extract purely scientific information, such as large-scale porosity, on large Apollo samples while maintaining their pristine nature.

Oct. 15, 2015
noon - 12:50 p.m.
Geology 4677

Presented By:

• Journal Club -

Seminar Description coming soon.

Oct. 22, 2015
noon - 12:50 p.m.
GEOLOGY 4677

Presented By:

• Lior Rubanenko - UCLA

First contact? Kepler's Abnormal Discovery Around KIC 12557548

The Kepler space telescope was originally designed to discover exoplanets using the transit method. Recently, several stars have shown to behave abnormally compared to regular transit patterns; instead of one, periodical dip, the light-curve shows several dips in unequal sizes. We will discuss the possible sources of this abnormal behavior - some natural: an exo-Oort cloud, a transiting comet - and some artificial: a planet size mega structure created by an advanced alien race. The talk will follow Arnold (2005), Boyajian et al (2015) and Wright et al (2015).

Oct. 29, 2015
noon - 12:50 p.m.
Geology 4677

Presented By:

• Ky Hugshon - UCLA

Geomorphological evidence for ground ice on Ceres from lobate flows as seen by Dawn

Five decades of observations of Ceres’ albedo, surface composition, shape and density by Earth and space based telescopes suggest that Ceres is comprised of both silicates and several tens of percent water ice (McCord et al., 2010). Ceres’ bulk density of ~2100 kg/m3 (McCord and Sortin, 2005) and the detection of OH and water emissions from the Herschel Space Observatory (Küppers et al., 2014) all support this conclusion. From initial Dawn data we report geomorphological evidence for ground ice on Ceres in the form of ubiquitous flow features. The observed features exist on a morphological continuum between two endmembers: (1) thick, domical flows with well-developed snouts, and (2) thin, sheeted, multi-lobed flows with very long runouts. We interpret these features to be similar to ice-cored or ice-cemented flows, and ballistically emplaced fluidized ejecta respectively. A large population of morphologically intermediate flows also exists; they have been interpreted as being a mix of long-runout landslides and fluidized ejecta emplaced as surface flows.

Nov. 5, 2015
noon - 12:50 p.m.
Geology 4677

Presented By:

• DPS -

Seminar Description coming soon.

Nov. 12, 2015
noon - 12:50 p.m.
Geology 4677

Presented By:

• Jonathan Cheng - UCLA

Characterizing convection in geophysical dynamo systems

The Earth's magnetic field is produced by a fluid dynamo in the molten iron outer core. This geodynamo is driven by fluid motions induced by thermal and chemical convection and strongly influenced by rotational and magnetic field effects. While frequent observations are made of the morphology and time-dependent field behavior, flow dynamics in the core are all but inaccessible to direct measurement. Thus, forward models are essential for exploring the relationship between the geomagnetic field and its underlying fluid physics.

In this talk, I will discuss a suite of nonrotating and rotating convection laboratory experiments reaching more extreme values of the governing parameters than previously possible. My experiments show that the regimes where numerical models produce Earth-like magnetic fields dwindle as more geophysical values of the governing parameters are achieved. Instead, comparison with numerical results indicates that regimes characterized by geostrophic turbulence are more likely to apply to the Earth’s core.

I will also discuss a theoretical analysis of results from a suite of dynamo simulations by Christensen and Aubert (2006). These results are broadly used in the geophysics community for describing the heat transfer, magnetic field, and velocity scaling properties in planets and stars. However, I find that the scaling laws derived from these simulations are fully dependent on the fluid viscosity, and therefore are unlikely to reflect the fluid physics driving dynamo action in the core. My findings reinforce the need to understand the turbulent flows underlying the geodynamo.

Nov. 19, 2015
noon - 12:50 p.m.
Geology 4677

Presented By:

• Morgan O’Neill - Weizmann Institute

Seminar Description coming soon.

Nov. 26, 2015
noon - 12:50 p.m.
Geology 4677

Presented By:

No seminar today

Dec. 4, 2015
noon - 12:50 p.m.
Geology 4677

Presented By:

• Journal Club -

Seminar Description coming soon.