The School of Earth and Atmospheric Sciences Presents Dr. Hao Cao, Harvard University
A Magnetic Perspective on the Interiors of Saturn and Mercury
Magnetic fields are windows into planetary interiors. The existence and properties of the planetary magnetic fields reflect the interior structure, dynamics, and evolution of the host planets. Recent observations from the MESSENGER, the Cassini, and the Juno missions have revealed many surprising features in the magnetic fields and interiors of Mercury, Saturn, and Jupiter, respectively.
In this talk, I will mainly present my analyses and interpretations of the magnetic fields of Saturn and Mercury. For Saturn, the new features of the planet’s magnetic field revealed by the Cassini Grand Finale will be reported, including the small-scale axisymmetric magnetic structures and the new upper limit on the non-axisymmetry of the field. Implications on deep zonal flows (differential rotation) and stable stratification inside Saturn will be discussed.
For Mercury, with the help of numerical dynamo experiments, I will show that the peculiar north-south asymmetry in Mercury’s magnetic field can be reconciled with the slow rotation of Mercury, extensive iron snow within Mercury’s liquid core, and a relatively small solid inner core.
In closing, I will highlight the magnetic aspects of the ongoing Juno mission and a few upcoming planetary missions (e.g. Psyche mission to asteroid 16 Psyche, Clipper to Europa, BepiColombo to Mercury, JUICE to Ganymede, and a possible mission to Uranus/Neptune) and how they will help answer questions ranging from the thermal evolution history of asteroid 16 Psyche to the salinity of Europa’s ocean.
The School of Earth and Atmospheric Sciences Presents Dr. Christopher Milliner, NASA Jet Propulsion Laboratory
Using Novel Geodetic Imaging Techniques to Understand How Faults Release Strain and Track Water Storage Changes Following Extreme Hydrologic Events
Measurements of surface deformation using geodetic imaging techniques can provide observational constraints on the way faults rupture the surface and the amount of terrestrial water mass held in a region.
Recent advancements in the resolution of optical satellite imagery, increasing density of continuous GPS networks, and near-global coverage of radar interferometry (InSAR), now offer a diverse toolset with which to study fault zone deformation and transient hydrologic processes. Here, I will first show how the use of pixel tracking applied to satellite images taken before and after two large-magnitude earthquakes can provide spatially complete measurements of the strain distribution across the fault damage zone.
I will explore how these observations can deepen our understanding of faulting kinematics and mechanics such as, how the magnitude and width of inelastic strain may differ between fault systems, to variations of slip along ruptures and with depth.
Second, I will show how networks of continuous GPS stations can be used to track transient changes in terrestrial water storage following extreme precipitation events, such as large hurricanes.
The mass loading effect of water on Earth’s elastic crust causes millimeter subsidence and uplift as water accumulates and dissipates, respectively, which can be measured using precise GPS elevation positioning. Using GPS measurements of elevation changes following Hurricane Harvey I will show we can infer a region’s hydrologic properties, from the amount of water a drainage area can hold, to how fast an area can dissipate water and by what means.
The use of emerging geodetic techniques, with higher rate and more precise positioning, now allows new approaches to characterize the seismic hazard faults pose to the built environment, how faults accumulate and release strain, and improved monitoring of a region’s water security and preparation for future extreme precipitation events.
The School of Earth and Atmospheric Sciences Presents Dr. Matthew Siegler, NASA Jet Propulsion Laboratory
Dr. Matthew Siegler will provide an overview of ongoing and future geothermal heat flow projects on the Moon and Mars. We will look at the recently landed InSight mission, new analysis of Apollo heat flow data, Orbital microwave-wavelength measurements, and a dawning era of or subsurface planetary exploration and planetary geophysics.
The School of Earth and Atmospheric Sciences Presents Dr. Elvira Mulyukova, Yale University
Grain Scale Physics of Plate Boundaries: Tectonic Processes from Geological to Human Time Scales
The motion of tectonic plates along our planet’s surface shapes the relationship between the solid Earth and its surrounding elements, including the atmosphere, ocean, and life.
Examples include the chemical reactions between minerals and water at seafloor spreading centers, as well as volcanic degassing at subduction zones, both of which link plate tectonics to the global volatile cycles. Furthermore, volcanism and seismicity along plate boundaries have a clear impact on human life.
However, Earth is enigmatic in that it is the only known terrestrial body that has plate tectonics. Understanding how plates and plate boundaries form and evolve is fundamental to our understanding of the Earth system as a whole.
In order for a new tectonic plate to form, the cold and stiff oceanic lithosphere must be weakened sufficiently to deform at tectonic rates. The weakening mechanisms involve the microscale physics of mineral grains and their control on the strength of the lithosphere.
In this talk, I will present the microphysics of lithospheric weakening by mineral grain size reduction, known as grain damage, and its application to tectonic scale processes, such as subduction initiation.
I will also present the newly developed theory of grain mechanics, which couples evolution of grain size and intragranular defects. The new model predicts oscillations in grain size, and possibly material strength, on a time scale that is relevant to earthquake cycles and postseismic recovery, thus connecting plate boundary formation processes to the human time scale.
The School of Earth and Atmospheric Sciences Presents Dr. Laura Stevens, Columbia University
Mass loss from the Greenland Ice Sheet contributes a quarter of today’s global sea level rise. Roughly half of this Greenland Ice Sheet mass loss is derived from accelerated flow of the ice sheet due in part to the ability of surface meltwater to access, lubricate, and enhance sliding along the ice-bed interface.
Determining the processes that govern the ice sheet’s dynamic flow response to increased surface meltwater production is critical for understanding how ice sheets work and predicting how ice sheets will behave in our warming climate.
This talk will examine the influence of meltwater on two regimes of Greenland Ice Sheet flow: (1) rapid supraglacial lake drainages in the slowly-flowing inland margin, and (2) diurnal meltwater influences on fast-flowing marine-terminating outlet glaciers.
A combination of Global Positioning System (GPS) observations of ice-sheet surface displacement, inverse methods, and time series analysis will be used to investigate these processes.
In the slow-flowing regime, rapid supraglacial lake drainages provide an ideal natural experiment that enables us to probe the upper limits of meltwater’s influence on ice-flow acceleration. These lake drainages are spectacular events, where hydro-fractures—water-driven crevasses—drain ~3-km diameter lakes from the surface to the bed of the ice sheet in a matter of hours at rates equivalent to the discharge across Niagara Falls.
This half of the talk will investigate what triggers rapid lake drainage using a Network Inversion Filter (NIF) to invert a dense, local network of GPS observations during three lake drainage events.
In the fast-flowing regime, marine-terminating outlet glaciers are the gatekeepers of the inland ice sheet’s access to the sea. The dynamics of these glaciers are governed by complex interactions between the atmosphere, ocean, and ice-sheet bed.
This half of the talk will investigate how atmospheric and oceanic forcing influence short-term (hourly) variations in horizontal flow of Helheim Glacier, East Greenland as observed by an array of GPS receivers. Improved mechanistic understanding of how tidal and atmospheric forcing drive marine outlet glacier flow is critical for determining how rapidly ice will be discharged into the ocean as these regions warm.
The School of Earth and Atmospheric Sciences Presents Dr. Wing Yin "Winnie" Chu, Stanford University
The last decade has seen significant advancements in our understanding of ice sheet hydrology and in particular, the role of subsurface drainage hidden within and beneath the ice sheets.
Radar sounding is one of the few unique geophysical tools that allow us to image and constrain processes occur in these traditionally difficult-to-observe subsurface environments. Nonetheless, despite their usefulness, robust analysis of radar sounding data face several technical challenges.
These include uncertainties related to spatially variable attenuation losses and roughness scattering. As a result, applications of ice-penetrating radar have so far been limited to local-scale studies and mapping distribution of static water within and beneath the glaciers.
In this talk, I will present novel methods where I combine ice-penetrating radar and numerical ice-sheet modeling to extract additional information from radar sounding data. I will demonstrate how we can apply this joint radar-model technique to gain new geophysical insights into the structure and dynamics of subsurface drainage systems in the Greenland ice sheet.
I will delve into the importance of understanding the large-scale characteristics of these systems for the overall dynamics of ice sheets and their response to surface melting.
The School of Earth and Atmospheric Sciences Presents Dr. Joseph O'Rourke, Arizona State University
Vigorous fluid motions drive dynamos today in Earth and all major planets except Mars and Venus. Here, I will show how magnetic histories of rock/metal planets directly depend on conditions during their accretion and differentiation.
In particular, giant impacts and planetary size and water content are always critical to dynamo energetics. Precipitation of magnesium oxide boosts the likelihood of dynamo activity in Earth and Venus, but hydrogenation of the core of Mars destroyed its dynamo.
My future plans center on comparative planetology to understand fundamental interior processes that affect planetary atmospheres and surfaces. In parallel with computational geodynamics, I aim to develop spacecraft missions that provide ground truth for my models. To illustrate, I will present my proposed SmallSat mission to (2) Pallas—the largest unexplored protoplanet in the main asteroid belt and parent of many near-Earth asteroids.
The School of Earth and Atmospheric Sciences Presents Dr. Michael Sori, Univeristy of Arizona
Ceres, the largest object in the asteroid belt, has been revealed by NASA’s Dawn mission to be a complex geophysical world. Its transitional nature – somewhere between icy and rocky, asteroid and planet – allows Ceres to elucidate a number of planetary processes.
In this talk, I will focus on icy volcanism, also called cryovolcanism. I will argue that surface features show Ceres to be geologically active, and geophysical models constrain its cryovolcanic rate. The level of activity I infer shows that cryovolcanism is an important geological process in the solar system, but is not as dominant as silicate volcanism.
I will end by discussing ways in which the geophysical techniques here can be used to study other topics on Mars, Mercury, the Moon, and Ceres, including how the Dawn data can be used to investigate ice deformation, the faint young sun, and planetary differentiation.
Editor's Note. This story was published originally by the Scheller School of Business on Dec. 12, 2018. It has been adapted for the College of Sciences.
Georgia Tech’s Carbon Reduction Challenge (CRC), a program that helps students design and implement large-scale projects to save energy, received two first-place awards at the 2019 Reimagine Education Conference & Awards in San Francisco. The international competition spotlights innovative initiatives aimed at enhancing student learning outcomes and employability across five disciplines and 17 categories.
The CRC is co-directed by College of Sciences Professor and Georgia Tech Global Change Program Director Kim Cobb and Scheller College of Business Professor and Ray C. Anderson Center for Sustainable Business (“Center”) Faculty Director Beril Toktay. The CRC pairs teams of undergraduate students with a diverse set of local organizations to identify opportunities for large-scale energy efficiency gains that will save greenhouse gas emissions and deliver significant energy cost savings.
This year’s competition received 1,184 project submissions from 39 countries. Submissions were evaluated by 160 international judges. The CRC won first place in the “Sustainability” category as well as first place in the “Natural Sciences” discipline. It was also selected as one of ten finalists to advance to the Grand Finale.
The CRC began as a class project that Cobb initiated in 2007. In 2017, it was expanded to include co-op and internship students across Georgia Tech in collaboration with Toktay and with funding from the Ray C. Anderson Foundation’s NextGen Committee and the Scheller College of Business Dean’s Innovation Fund. It also became an affiliated project of the Georgia Tech Serve-Learn-Sustain initiative.
In 2018, the CRC expanded its reach by inviting Emory University students to participate as well. The CRC became an official activity of the Georgia Climate Project, a statewide, multi-year effort to improve understanding of climate impacts and solutions across the state and to encourage Georgia residents to take effective, science-based climate action. CRC projects launched since 2017 have already resulted in over two million pounds of avoided CO2 emissions and are projected to deliver hundreds of thousands of dollars in avoided energy costs to partner organizations. Finalists present their projects at a public poster expo, and judges score projects to decide the winners who receive cash prizes thanks to a gift from the Sheth Family Foundation.
Reimagine Education is sponsored in part by the Alfred West Jr. Learning Lab of the Wharton School of Business at the University of Pennsylvania.
Lucas R. Liuzzo is the first in his immediate family to receive a college education.
He grew up in Jamestown, New York, which has about 30,000 residents. For his undergraduate degree, he attended the University of Michigan, in Ann Arbor.
The transition to living in a city with four times the population of his home town was difficult. “I wasn’t sure I could even survive in such a new environment. But I loved it,” Lucas says.
Ann Arbor’s big-city-yet-small-town gave Lucas the freedom to develop into a thriving young-adult. He graduated with a B.S. in Engineering in 2014. He could have stayed in Michigan to pursue graduate studies in solar space physics.
Instead, Lucas chose to try something different and make new connections. His next move was to Atlanta, an even bigger city than Ann Arbor. At Georgia Tech, he studied magnetospheric space physics. He graduates with a Ph.D. in Earth and Atmospheric Sciences.
What is the most important thing you learned at Georgia Tech?
Performing research at Georgia Tech is at the cutting edge of science, where spending days, weeks, or even months on a problem isn’t unheard of. Sometimes your method can simply send you down the wrong path, which can be extraordinarily frustrating. Graduate school has shown me that hard work and diligence do not often mean you’re on the right path, but that’s exactly the point of academic research.
When finally you reach the solution to an especially difficult problem, it is extremely gratifying, even if you may be the only person in the world who knows the answer.
What is your proudest achievement at Georgia Tech?
Defending my dissertation.
It has taken me five years to obtain my Ph.D. I’m not sure I’ve ever put so much time and dedication into anything over such a long stretch of time. I’m very proud of my efforts culminating in my degree from Georgia Tech.
Which professor(s) or class(es) made a big impact on you?
My advisor, Sven Simon, afforded me every opportunity to become the best I could be scientifically. He supported me throughout my time here.
The most impactful classes were the engineering courses with Morris Cohen and Waymond Scott, in the School of Electrical and Computer Engineering. These courses helped me to appreciate other academic disciplines that share many complementary theoretical approaches with my own, but can be drastically different in application.
What is your most vivid memory of Georgia Tech?
The changing seasons, which I looked forward to year after year of studying at Tech.
Georgia Tech has a beautiful campus, but the four seasons bring out its true beauty. I arrived in August during the dog days of summer. I’ve never been so consistently hot and sticky for so many consecutive days.
Surviving the Atlanta summer is rewarded with a gorgeous fall. Brilliant oranges, yellows, and reds of the foliage dot the trees on campus. It’s a sight to behold.
This beauty is topped on the rare occasion of an Atlanta winter snowfall. Staring across Tech Green at the Campanile dusted in a slight layer of clean, white, crisp snow is magical.
The cold days of winter are as short-lived as the daylight during this time of year. The spring that follows colors the campus in tree blossoms that rival a Bob Ross painting. On campus during spring, even the pollen is Tech Gold.
In what ways did your time at Georgia Tech transform your life?
Academically and professionally I wouldn’t be the person I am today without my Georgia Tech degree. Personally, I’ve made everlasting friendships with amazing individuals who have had a huge impact on who I have become.
What unique learning activities did you undertake?
I attended conferences abroad and worked with colleagues in Germany. During those few weeks working and living in a country that was entirely new and foreign to me, I formed bonds – professional and personal – that will last a lifetime.
What advice would you give to incoming graduate students at Georgia Tech?
Don’t be afraid to step out of your comfort zone. In graduate school, it’s easy to fall into the doldrums of research and follow the same routine, day after day.
Break out of the campus bubble, explore the city, and find your niche. Between classes, research, and conferences, your days fill up quickly. Be sure to take breaks.
While Tech offers lots of opportunities to relax, Atlanta is a huge, diverse city. It’s important – and often liberating – to explore your surroundings and talk with individuals who aren’t students themselves.
Where are you headed after graduation?
I’ll be at Tech for a few months working as a postdoctoral researcher. I’ll be working in the same group as my graduate studies, so I’m already 100% up to speed with my research topic and can start making meaningful progress right from the start.