Spring 2015

April 10, 2015

Morten Jakobsen, Bergen University

Title: Seismic fracture characterization and full waveform inversion using multiple scattering theory


April 17, 2015

Jason Barnes, University of Idaho

Title: Titan's Dynamic Seas


April 24, 2015

Oliver White, NASA Ames

Title: Modeling of Sublimation-Driven Erosion and Ice Pinnacle Formation on Callisto


May 1, 2015

Serina Diniega, JPL

Title: Planetary Geomorphology: Comparisons and contrasts between Earth and Mars dunes and gullies

Abstract: Comparative geomorphology is a standard and highly useful approach in determining the origin of features seen on planetary surfaces. Essentially, this involves finding an Earth feature that looks similar, and then assuming a similar formation process. Sometimes this works well: for example, studies of sand dunes forming under non-Earth conditions have expanded our understanding of processes observed on the Earth. However, this approach sometimes can point interpretations into the wrong direction – the specific and sometimes highly unique conditions found on another planet cannot be neglected in the analysis! In particular, long, narrow grooves found on the slopes of Martian sand dunes have been cited as evidence of liquid water via the hypothesis of melt-water initiated debris flows. We proposed an alternative hypothesis: blocks of CO2 ice (AKA dry ice) that form naturally on the dune surfaces each winter may fall onto and slide down the dune slope, “hovercrafting” downslope and carving out features such as those observed. This presentation will overview my studies of these Martian landforms.
 
Serina Diniega is a mathematical planetary geomorphologist -- meaning that she enjoys explaining why landforms look the way they do on different planets, and approaches these problems by putting them within a mathematical framework that captures the physical processes acting on that landscape. She started at JPL as a NASA Postdoctoral Program (NPP) fellow in the Planetary Geology and Geophysics group at JPL, and has since worked in operations for the Mars Reconnaissance Orbiter, as a science facilitator for the NASA Mars Program Office, and as Project Scientist for a Discovery mission proposal. She also still tries to do science focusing on present-day activity and interpretation of Martian landforms, including sand dunes/ripples, gullies, and lava flows. Serina received her PhD in Applied Math (minor: Planetary Science) from the University of Arizona in 2010; her dissertation work explored pattern formation in dune field evolution on Earth and Mars. She received her BS in Math in 2003 from Caltech, where she discovered her interest in planetary geomorphological modeling.


May 8, 2015

E&PS Alumni Reunion


May 15, 2015

TBA

Title: TBA


May 22, 2015

Rob de Rosa, UCB

Title: The Gemini Planet Imager Exoplanet Survey

Abstract: Measuring the frequency and distribution of extrasolar planetary systems provides crucial context to understand the formation of our own Solar System. While ongoing radial velocity and transit surveys are beginning to have sensitivity to terrestrial planets at separations similar to those within our own Solar Systems, wider Jovian-mass planets remain out of reach. Direct imaging provides a complementary detection technique, being sensitive to the thermal emission from young gas giants in wide (>10 AU) orbits around nearby (<100 pc) stars. Using a high-order adaptive optics system, an apodized pupil coronagraph, and an integral field spectrograph, the recently commissioned Gemini Planet Imager (GPI) was designed to directly image such planetary systems. Our team is currently undertaking an 890-hour campaign — the Gemini Planet Imager Exoplanet Survey (GPIES) — to search for planetary-mass companions in wide orbits (4-40 AU) around a sample of 600 nearby, young (<300 Myrs) stars. I will discuss the current status of the survey, which began in late 2014, and highlight several science results derived from commissioning and campaign observations.


May 29, 2015

Sarah Barrett, Stanford

Title: Dig a Little Deeper: Intermediate-depth earthquakes in the Bucaramanga nest