Astronomy, Environmental Science, Physics, Astronomy and Physics
Diana Davis Spencer Discovery Center 1331
I am a planetary scientist, using the tools of geology, geophysics, and remote sensing to explore other worlds in our solar system. The amazing diversity of places to explore gives us great perspective on how our own planet works, and in what ways the Earth is unique. I am specifically interested in how geology works on the ice-covered ocean worlds of the outer solar system, and what geology can tell us about the possibly habitable environments within those alien oceans.
When I am not in front of a computer working with data from distant spacecraft, I love to be working outdoors with students. Whether it is leading geology field trips, taking data in the Wheaton Woods, working with the outdoors club, or leading student field research classes in Death Valley or Iceland, I have seen so many students have their “eureka!” moments when they are completely immersed in the Earth’s environment.
Ph.D., Brown University
B.A., Carleton College
Space exploration holds the key to age-old questions like “Where do we come from? Are we alone? Is the Earth the only place where life can exist?” I believe that exploration of ocean worlds in the outer solar system will revolutionize our perspective on questions like these. As a geologist, I strive to use the surface features we find on the icy surfaces of ocean worlds to interpret the physical processes that control their current behavior and evolution through time.
I am currently a member of the science team on NASA’s Europa Clipper mission, working with the cameras on the spacecraft and helping to ensure that the mission will fulfill its geological goals. It takes a long time to build and fly a mission to the outer solar system, so in the meantime my students and I are still extracting new information from Galileo, the last mission to visit Europa. In recent years, we have been investigating whether Europa has an Earth-like system of plate tectonics on its surface, and how to form the strange double-ridge structures that cover Europa’s surface.
There are many other ocean worlds and icy bodies with interesting geological puzzles to solve, and I have many other ongoing projects covering places like Ganymede, Enceladus, Rhea, Titan, Pluto, and Charon. (see the publications tab for more information) Students in my lab get to work at the forefront of planetary research, interact with colleagues from NASA centers, and often travel to present their results at international conferences.
I love to introduce students to the wonders of the solar system and the deep history of our own Earth. I strive to teach science as an exploratory and creative process, emphasizing independent projects where students can apply what they have learned to something that personally interests them. The classes I teach include:
Geology, an introductory course where students learn about how the Earth works today, how we have reconstructed the history of our planet, and the effects of human decisions on Earth systems.
Geophysics, an upper-level course about the physical processes that govern the behavior of solid planets.
Remote Sensing, a course for students to develop skills in satellite data processing and interpretation, to monitor the Earth’s environment from space.
Astrobiology, an advanced seminar open to all science majors who want to explore current research on the origin of life on Earth and the possibility of extraterrestrial life.
Rocket Science, an introductory course about the physics and engineering of space exploration.
Field Geology, a student-driven and project-based course that has taken different forms depending on the field venue; most recently this course took the form of a faculty-led study abroad program in Iceland.
I have authored or co-authored nearly 50 peer-reviewed publications (see my CV for the complete list and for full bibliographic citations). Below is a selection of research I have published since coming to Wheaton, starting from the outermost fringes of the solar system and working inward. Please email me if you want a copy of any of these publications.
Europa: The surface of Jupiter’s moon Europa abounds with bizarre geological features. I am particularly interested in what causes disrupted areas of the surface, known as “chaotic terrain.” I also led an intensive analysis of possible plate tectonic motions on Europa’s surface, assisted by many Wheaton students including Ben Cutler ’17, Craig Rezza ’18, and Samantha Oldrid ’20.
G. Collins, G. W. Patterson, C. Detelich, L. Prockter, S. Kattenhorn, C. Cooper, A. Rhoden, B. Cutler, S. Oldrid, R. Perkins, and C. Rezza, Episodic plate tectonics on Europa: Evidence for widespread patches of mobile-lid behavior in the antijovian hemisphere, Journal of Geophysical Research, 2022.
G. Collins and F. Nimmo, Chaotic terrain on Europa, in Europa, University of Arizona Press, 2009.
J. Goodman, G. Collins, J. Marshall, and R. Pierrehumbert, Hydrothermal plume dynamics on Europa: Implications for chaos formation, Journal of Geophysical Research, 2004.
G. Collins, J. Head, R. Pappalardo, and N. Spaun, Evaluation of models for the formation of chaotic terrain on Europa, Journal of Geophysical Research, 2000.
Ganymede: The largest moon in the solar system was the main focus of my Ph.D. thesis, and since that time I have continued to work on the question of why Ganymede started to tear itself apart halfway through its geological history. I also led the effort to produce a complete geological map of Ganymede’s surface based on data from the Galileo and Voyager missions, and my research student Jon Kay ’08 played a large role in that project. Recently, I was on the team interpreting the new images of Ganymede returned by the Juno spacecraft.
M. Ravine, C. Hansen, G. Collins, P. Schenk, and six others, Ganymede observations by JunoCam on Juno perijove 34, Geophysical Research Letters, 2022.
M. Cameron, F. Seifert, B. Smith-Konter, G. Collins, L. Burkhard, and R. Pappalardo, Morphological mapping of Ganymede: Investigating the role of strike-slip tectonics in the evolution of terrain types, Icarus, 2018.
D. Sims, D. Wyrick, D. Ferrill, A. Morris, G. Collins, R. Pappalardo, and S. Colton, Physical models of grooved terrain tectonics on Ganymede, Geophysical Research Letters, 2014.
G. Collins, G. W. Patterson, J. Head, R. Pappalardo, L. Prockter, B. Lucchitta, and J. Kay, Global geological map of Ganymede, United States Geological Survey Science Investigations Map Series #3237, 2013.
R. Pappalardo and G. Collins, Strained craters on Ganymede, Journal of Structural Geology, 2005.
Pluto & Charon: My research student Madison Borrelli ’18 studied the origin of smooth plains on Pluto’s moon Charon, and I have also worked on the effects of orbital evolution in the Pluto-Charon system, and continue to pursue the question of how tides affected Pluto’s interior.
M. Borrelli and G. Collins, Testing the cryovolcanism and plate bending hypotheses for Charon’s smooth plains, Icarus, 2020.
A. Barr and G. Collins, Tectonic activity on Pluto after the Charon-forming impact, Icarus, 2015.
Enceladus: This tiny moon of Saturn surprised us all with its incredible activity, and I have worked on various geological puzzles to understand the tectonics of Enceladus, along with my former research students Emily Martin ’06 and Louie Michaud ’08. Fellow physics professor Jason Goodman and I also published the first evidence for an unusual body of trapped water as an explanation for the activity at the south pole.
E. Martin, J. Whitten, S. Kattenhorn, G. Collins, B. Southworth, L. Wiser, and S. Prindle, Measurements of regolith thickness on Enceladus: Uncovering the record of plume activity, Icarus, 2023.
G. W. Patterson, S. Kattenhorn, P. Helfenstein, G. Collins, and R. Pappalardo, The geological history of Enceladus, in Enceladus and the Icy Moons of Saturn, University of Arizona Press, 2018.
E. Martin, S. Kattenhorn, G. Collins, R. L. Michaud, R. Pappalardo, and D. Wyrick, Pit chains on Enceladus signal the recent tectonic dissection of the ancient cratered terrain, Icarus, 2017.
G. Collins and J. Goodman, Enceladus’ south polar sea, Icarus, 2007.
Titan: I was fascinated by the discovery of rivers of liquid methane on the surface of Saturn’s moon Titan, and worked to understand how similar they are to rivers on Earth.
D. Burr, M. Ádámkovics, V. Baker, G. Collins, A. Howard, R. Irwin, M. Lamb, J. Moore, J. Perron, L. Sklar, S. Drummond, and B. Black, Fluvial features on Titan, Geological Society of America Bulletin, 2013.
K. Litwin, B. Zygielbaum, P. Polito, L. Sklar, and G. Collins, Influence of temperature, composition, and grain size on the tensile failure of water ice: Implications for erosion on Titan, Journal of Geophysical Research, 2012.
G. Collins, Relative rates of fluvial bedrock incision on Titan and Earth, Geophysical Research Letters, 2005.
General papers about icy satellites and ocean worlds: Some of my research strives to find commonalities in the mechanisms that drive tectonics on the icy moons of the outer solar system. I have also worked in the area of planetary protection policy to prevent the harmful contamination of ocean worlds by Earth life.
P. Rettberg and 20 others, Biological contamination prevention for outer solar system moons of biological interest – What do we need to know? Astrobiology, 2019.
M. Sogin, G. Collins, A. Baker, J. Baross, A. Barr, W. Boynton, C. Cockell, M. Daly, J. Fragola, R. Lopes, K. Nealson, D. Stetson, and M. Thiemens, Assessment of Planetary Protection Requirements for Spacecraft Missions to Icy Solar System Bodies, National Academies Press, 2012.
G. Collins, W. McKinnon, J. Moore, F. Nimmo, R. Pappalardo, L. Prockter, and P. Schenk, Tectonics of the outer planet satellites, in Planetary Tectonics, Cambridge University Press, 2010.
J. Wahr, Z. Selvans, A. Barr, G. Collins, M. Mullen, M. Selvans, and R. Pappalardo, Modeling stresses on satellites due to non-synchronous rotation and orbital eccentricity using gravitational potential theory, Icarus, 2009.
The Moon: I have also used the software I developed for calculating tidal effects of giant planets on their moons to calculate what is currently happening to our own Moon as its orbit pulls away from the Earth.
T. Watters, R. Weber, G. Collins, I. Howley, N. Schmerr, and C. Johnson, Shallow seismic activity and young thrust faults on the Moon, Nature Geoscience, 2019.
T. Watters, M. Robinson, G. Collins, M. Banks, K. Daud, N. Williams, and M. Selvans, Global thrust faulting on the Moon and the influence of tidal stresses, Geology, 2015.
Several of my undergraduate research students have given presentations at major scientific conferences. For example:
Ishaan Madan ’22 gave a talk at the 2020 virtual meeting of the American Geophysical Union titled “Long-term Stability of Glycine, Alanine, and Phenylalanine on Titan’s Surface Subject to Cosmic Ray Flux” and then in spring of 2022 presented a poster titled “Characterizing phase transitions for Titan’s surface molecules: Implications for DraMS and Dragonfly” at the Lunar and Planetary Science Conference in Houston, Texas.
Madison Borrelli ’18 presented a poster in 2018 titled “Volcanism in Vulcan Planum: Topographic tests for the emplacement of smooth plains on Charon” at the Lunar and Planetary Science Conference and then another poster titled “Testing the cryovolcanism hypothesis for Vulcan Planum, Charon” at the Cryovolcanism in the Solar System Workshop in Houston, Texas.
Craig Rezza ’18 presented a poster in 2017 titled “Multi-stage reconstruction of plate motions south of Castalia Macula, Europa” at the Lunar and Planetary Science Conference in Houston, Texas.
Ben Cutler ’17 presented a poster in 2015 titled “Reconstructing plate motions on Europa with GPlates” at the American Geophysical Union Fall Meeting in San Francisco, California.
Brent Landry ’14 and Lily Munsill ’15 presented a poster in 2014 titled “Observations about boulders on the south polar terrain of Enceladus” at the Lunar and Planetary Science Conference in Houston, Texas.
Scott Tarlow ’12 presented a poster in 2010 titled “Fault scarp offsets and fault population analysis on Dione” at the American Geophysical Union Fall Meeting in San Francisco, California.
Noemie Goff-Pochat ’10 presented a poster in 2009 titled “Thermal weathering on airless planetary surfaces” at the American Geophysical Union Fall Meeting in San Francisco, California, and a poster titled “Strain measurement across fault scarps on Dione” and another poster in 2008 titled “Searching for strained craters on Enceladus” at the Lunar and Planetary Science Conference in Houston, Texas.
Jon Kay ’08 presented a poster in 2008 titled “Using discharge and precipitation to estimate runoff coefficients on Titan” and another poster in 2007 titled “Comparison of crater classification schemes on Ganymede” at the Lunar and Planetary Science Conference in Houston, Texas.
Louie Michaud ’08 was selected to give an oral presentation in 2008 titled “Pit chains on Enceladus: A discussion of their origin” and another poster in 2007 titled “Comparison of strain measurement methods on Ganymede grooved terrain: Deformed craters vs. fault geometry” at the Lunar and Planetary Science Conference in Houston, Texas.
Emily Martin ’06 presented a poster in 2006 titled “Computer assisted time sequence sorting of grooves in eastern Mysia Sulci, Ganymede” at the Lunar and Planetary Science Conference in Houston, Texas.
John McBee ’04 and Dan Hartmann ’04 presented a poster in 2003 titled “Strain across ridges on Europa” at the Lunar and Planetary Science Conference in Houston, Texas.
Karrie-Sue Farrar ’03 presented a poster in 2002 titled “Global mapping of Ganymede impact features” at the Lunar and Planetary Science Conference in Houston, Texas.
I have been the primary advisor on seven undergraduate honors theses:
Claire Hammond ’20: “Analog modeling of contractional strain on Europa”
Keaton Schrank ’19: “Monitoring vegetation health in the Great Marsh: 25 years of satellite observations and freshwater input data”
Grace Genszler ’18: “Numerical Analysis of Periodic Motion of Tethered Satellite Systems”
Noemie Goff-Pochat ’10: “Thermal Weathering on Airless Planetary Bodies in our Solar System”
Megan O’Sadnick ’09: “Surface Abrasion in the Blue Ice Areas of Antarctica”
Jon Kay ’08: “Examining the Relationship between Rainfall, Discharge, and Infiltration on Saturn’s Moon Titan”
Louie Michaud ’08: “A Dilational Faulting Model for the Origin of Pit Chains on Enceladus”
I have also advised many undergraduate students on other independent scientific research projects. Students who spent more than one semester or summer doing research with me include:
Ishaan Madan ’22: Titan chemistry, survival of organic molecules on the surface and issues with future sample handling
Samantha Oldrid ’20: Europa plate definition and reconstruction trees
Craig Rezza ’18: Multi-stage tectonic reconstruction of western Argadnel Regio, Europa
Madison Borrelli ’18: Volcanism on Charon; Crater population statistics on Enceladus
Benjamin Cutler ’17: Implementing software to test hypotheses about plate tectonics on Europa
Jose Pablo Brenes Coto ’16: Map unit definition at Enceladus south pole; Cassini and Galileo image processing
Lily Munsill ’15: Boulder statistics on Enceladus south polar terrain
Brent Landry ’14: Cassini image processing and mapping of Enceladus’ south pole
Scott Tarlow ’12: Fault population analysis on Dione
Noemie Goff-Pochat ’10: Mapping and strain analysis of faults on Enceladus and Dione
Hannah di Cicco ’09: Searching for strained craters on Enceladus
Louie Michaud ’08: Strain measurements from fault geometry on Ganymede
Jonathan Kay ’08: Finalization of crater database for the global geological map of Ganymede
Emily Martin ’06: Classification of grooved terrain on Ganymede and testing methods for time-sequence sorting
Jennifer Savage ’06: Geological mapping of Ganymede
Rachel Fontaine ’04: Reconstructing the geometry of ancient impact basins on Ganymede and Callisto
Dan Hartmann ’04: New techniques for measuring strain across ridges on Europa
Matt Blake ’04: Morphology and mapping of chaotic terrain on Europa
Jon McBee ’04: Time sequence analysis of groove formation in Sippar Sulcus and leading hemisphere of Ganymede
Karrie-Sue Farrar ’03: Mapping and classification of craters on Ganymede