| School of Earth and Space Exploration

The Formation of Planets from the Direct Accretion of Pebbles

In recent years, a radical new scenario has recently been suggested for the formation of planets. This scenario, known as pebble accretion, envisions: 1) Planetesimals form directly from millimeter- to meter-sized objects (the pebbles) that are concentrated by hydrodynamic forces and then gravitationally collapse to form 100 - 1000 km objects. 2) These planetesimals quickly sweep up the remaining pebbles because their capture cross sections are significantly enhanced by aerodynamic drag.

Read more about Hal Levison Colloquium Abstract (Oct 25, 2017)

The Habitability of Planets Orbiting M Dwarfs

Recently discovered planets orbiting nearby M dwarfs will provide intriguing near-term targets for the James Webb Space Telescope and ground-based telescopes, and an exciting window into the evolution and nature of terrestrial planets. M dwarfs, although plentiful, undergo strong evolution in stellar brightness when they are young, and have habitable zones that are extremely close to the star.

Read more about Victoria Meadows Colloquium Abstract (Oct 18, 2017)

Using Machine Learning for Discovery on Earth, Mars and Beyond

“We are living in one of the most exciting and hyped eras of AI,” says Fei-Fei Li, Stanford University Professor and Chief Scientist of Artificial Intelligence and Machine Learning at Google Cloud. This statement certainly applies to machine learning as well. A search of the term “machine learning” on Google News reveals a daily onslaught of articles in the popular press. Consumers are just awakening to the fact that their Netflix queues and email spam filters use machine learning, and that critical t

Read more about Umaa Rebbapragada Colloquium Abstract (Sept 20, 2017)

Pluto Explored! NASA's Epic Voyage to the Edge of the Solar System

We have reached Pluto, the last of the classical planets, and the most remote world yet explored by humankind. Far from being dark, cold, and dead, Pluto and its family of moons are bright and variegated, if not gloriously, geologically alive.

Read more about William McKinnon Colloquium Abstract (Nov 29, 2017)

The Limits of Cosmology

One of our greatest challenges in cosmology is understanding the origin of the structure of the universe, and in particular the formation of the galaxies. I will describe how the fossil radiation from the beginning of the universe, the cosmic microwave background, has provided a window for probing the initial conditions from which structure evolved and seeded the formation of the galaxies, and the outstanding issues that remain to be resolved.

Read more about Joe Silk Colloquium Abstract (Nov 8, 2017)

Venus: The Forgotten, Mysterious Planet

Although Venus was likely similar to Earth after formation, the evolutionary pathways of the two planets have been vastly different. Venus is now a planet of extremes, with a runaway greenhouse atmosphere composed almost entirely of carbon dioxide, sulfuric acid clouds, and surface temperatures that could melt lead.

Read more about Lori Glaze Colloquium Abstract (Sept 27, 2017)

The Tectonic Evolution of the Central Andean Plateau and Geodynamic Implications for the Growth of Plateaus

Current end-member models for the geodynamic evolution of orogenic plateaus predict (1) slow-and-steady rise during crustal shortening and ablative subduction (i.e., continuous removal) of the lower lithosphere, or (2) rapid surface uplift following shortening, associated with punctuated removal of dense lower lithosphere and/or lower crustal flow.

Read more about Carmala Garzione Colloquium Abstract (Aug 30, 2017)

Human-Robot Teaming for Space Exploration

The future of space exploration will increasingly involve joint teams of humans and robots. Humans and robots have unique capabilities that can complement each other and that can enhance exploration. Robots can perform precursor tasks, such as reconnaissance, to prepare for future human activity. Robots can work in support of astronauts, assisting or performing tasks in parallel. Robots can also perform "follow-up" work, completing tasks designated or started by humans.

Read more about Terry Fong Colloquium Abstract (Oct 11, 2017)

Artifact SETI and the Puzzle of (Tabby) Boyajian's Star

I have been at the center of efforts to understand KIC 8462852, a strange star found during the Kepler mission. It exhibits deep, irregular "dips" or dimming events lasting days, up to 22% in depth, and appears to be dimming secularly on decadal timescales. As ever-more-contrived natural explanations are proposed and explored by my team and others, we continue to put together monitoring and target-of-opportunity programs to catch it "in the act" of dipping and determine the nature of the dips. In parallel, I

Read more about Jason Wright Colloquium Abstract (Oct 4, 2017)

Measuring Ancient Landscape Dynamics from Sedimentary Deposits

Internal, or autogenic, dynamics in sedimentary systems impart significant variability in sedimentation through space and time across Earth’s surface. These processes can produce depositional patterns that mimic stratigraphy generated by climate, tectonic, or eustatic forcing.

Read more about Elizabeth Hajek Colloquium Abstract (Sept 13, 2017)

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