Professor Eric Grosfils is engaging students in the cool science of comparative planetary geology.

Volcanoes have been around far longer than human beings and have played a significant role in shaping the very earth beneath our feet. Our awareness of them, however, tends to focus upon their lethal potential, for obvious reasons. Since 1800, a total of 19 volcanic eruptions have topped the 1,000 mark in their toll of human lives--from Krakatau (better known as Krakatoa) in 1883, which killed more than 36,000 people and was heard from Sri Lanka to Australia, to Colombia's Nevado del Ruiz in 1985, which sent a deadly volcanic mud-flow into the town of Armero, killing 23,000.

Like many geologists before him, Eric Grosfils has devoted a great deal of energy to understanding what makes these natural time-bombs tick--and, on a larger scale, to studying the role they play in shaping the surface of our planet. What sets his work apart, however, is that most of the volcanoes he studies are located on other worlds.

The field of comparative planetary geology was born with the space age, which saw a succession of robotic eyes sent to spy on our next-door neighbors in the solar system. For Grosfils, now an associate professor of geology at Pomona, the data from these missions to Mars and Venus came as a revelation. Here was a whole new way of doing geology.

"For geologists like me, who are interested in how specific geological processes work, how a volcano forms, how it erupts, how an earthquake builds a mountain, or how a sand dune moves along the surface," says Grosfils, "the presence of these other planets and information on their geology is terrific."

In many areas of science, he explains, you can run an experiment multiple times, each time altering a variable in some small way to gain a deeper understanding of an outcome or process. But that doesn't work for large geological processes. (You can't, after all, rewind a volcanic eruption.) However, studying the same geological process on Earth, Mars and Venus, each with a very different environment, works much the same way to give geologists a clearer understanding of how the process works.

"The Earth we know reasonably well," says Grosfils. "Mars has low gravity, is cold and has a very low atmospheric pressure. Venus has about the same gravity as the Earth but has a much greater surface pressure, equivalent at the surface to being a kilometer under Earth's ocean, and is hot enough at the surface to melt lead. The volcanic processes that build a volcano are affected by these differences.

"By taking our ideas about how things work, our theories developed from studying Earth, and trying to predict what we would see on Mars or on Venus, we can see whether we've gotten it right. More often than not, the theories don't work on other planets quite the way we thought they would, or the process works to predict, for example, lava flow length on Earth and Mars but not on Venus. Either case suggests that there is something we don't yet understand, and we have to come back to the drawing boards. It's an iterative process."

It is just this sort of process that Grosfils and a colleague at Goddard Space Center are undertaking to study the plumbing system under small volcanoes on Mars. By looking at the surface features of these volcanoes, he and his partner are attempting to develop a model incorporating rock strength and fracture properties, magma movement, pressurization and other variables, to predict heat sources and melting, ultimately leading to a theory that can accurately predict the mechanical failure causing the very shallow, almost ring-like depressions that surround these volcanoes.

"If things fail mechanically, the way we think that they will," says Grosfils, "it may tell us how much water and ice there is in the subsurface and what the geometry of the subsurface magma plumbing is like, generally. It's not going to give us ultra-high precision but it will give us a sense for what's going on.

"What's not clear yet is whether it's going to work. But even if it doesn't end up working quite the way we expect, we will still learn a tremendous amount, ultimately, about the processes. We still learn how magma reservoirs fail under pressure, which is something important for magma reservoirs on Earth, Mars and Venus."

At the same time, Grosfils is also working to map the Ganiki Planitia (V14) quadrangle of Venus to decipher the volcanic and tectonic history of the region and how it has evolved. It's the first time anyone has mapped the area, which is roughly one-third the size of the United States. When the work is complete, says Grosfils, "we will understand not only the sequence of events that formed the area, but hopefully, a lot more about the specific features within it."

One of the reasons Grosfils pursued the mapping project is that it enables him to bring students into his work. Currently six students are working on the project, and several others have participated over the past couple of years, funded from a variety of sources. The current group began while still taking their first geology class. "These are students who are learning what science is about," Grosfils emphasizes, "and this project gave me the opportunity to toss them straight into a really exciting, yet relatively difficult-to-perform, research project that they are quite capable of handling."

Working with special software, the students have compiled back-scatter radar images of Venus, information on material properties and topography data, all collected from NASA's Magellan spacecraft, which orbited the planet from 1990 to 1994. Visually, the compiled data is pretty spectacular. What makes it difficult, despite its 3-D images (yes, they wear those funny red-and-blue glasses), is the nature of radar back-scatter images. Though very detailed, they often only tell the viewer about the roughness differences at the surface.

To explain the difficulty this can cause, Grosfils suggests envisioning a new lava flow in Hawaii. "If it is in the middle of a bunch of previous lava flows, it might be really smooth near the top, but as it gets down to the bottom and crusts over and changes form, it might get really rough," he explains. "It's all the same unit but in the radar image it would be very dark where smooth and suddenly get bright. You might be tempted to put a unit boundary between that dark and that light because visually we're used to looking at those kinds of things. So you might create boundaries and look for relative time indicators where really there aren't any. All of the people studying these images are struggling with this issue right now, and there may not be an answer to it with the radar. It may be we just won't be able to understand the surface history as well as we'd like with just radar data alone."

The research students have now made their best estimate of the geologic boundaries and are examining the regional stratigraphy to determine what types of features are in the quadrangle. Next they will determine the sequence of events in the area's formation.

The six students engaged in this work are only the latest in a long line of fledgling geologists Grosfils has incorporated into his research projects over the years. During his nine years at Pomona, he has worked with more than 50 students on planetary projects, most of them studying Venus and Mars. "One of the things that is really important about the work I'm doing, at Pomona, in planetary science," he says, "isn't necessarily the leaps of incredible insight that I'm gaining in planetary work. It's my ability to engage students in it. Most of them have ended that work with a conference presentation of one sort or another. So they're doing presentation-worthy work at science conferences, and that's something that I'm really proud of."

The mapping project epitomizes the types of projects Grosfils prefers. "With the Venus project, I can fold in a freshman, in their first geology class, and have them working on substantial questions at the same time I fold in a senior working on his thesis. They'll be addressing questions at different levels and of different sophistication but all of them can get engaged. That's one of the things I think is really cool about what I do, and one of the things I really enjoy about the planetary sciences in a liberal arts setting."

It is not only his research students who benefit from Grosfils interplanetary research. In his geology classes, Grosfils also finds ways to incorporate the latest Mars data into the lab work, "so that students are working with it hands-on in the lab, almost as fast as the data comes out."

Grosfils work with students has not gone unnoticed. In 2001, he was recognized with one of the nation's most prestigious teaching awards in the geosciences, the Biggs Award for Excellence in Earth Science Teaching, awarded by The Geological Society of America (GSA). The award recognizes the accomplishments of exceptional college professors who have taught in the field of geology for 10 years or less.

Grosfils' goal in involving his students in his work, he says with a laugh, isn't "to create a bunch of me's. I'm not trying to create a gazillion planetary scientists out there, although it's really nice when every now and then a student does go on in graduate school and beyond." His primary goal, he says, is to make the study of the scientific method an exciting thing in and of itself. And for that, he admits, planetary geology is a decided plus. "It's just jazzy and cool. It sells itself as a way to engage students in understanding science."

—Cynthia Peters is Associate Director of Public Affairs for
Media Relations at Pomona College.

Photo by Phil Channing