Gazing at Soil from Space, an ISU Professor Fulfills Environmental Calling

Brian Hornbuckle holds a scale model of SMOS, the satellite launched by the European Space Agency. He's leading a team in Ames that is checking the satellite's work from the ground. - photo by Jim Malewitz

When Brian Hornbuckle cranes his neck to the nighttime sky, he’s probably not pondering the beauty of the constellations, but thinking about what’s in the Iowa soil right under his feet.  Yet he’s neither absent-minded, nor a contradiction. He’s just a man who has found his niche – where astronomy, physics and environmental science collide.

Through his work, Hornbuckle says he hopes to help keep agriculture profitable and to give Iowans better information on how to maintain soil and water quality, and a favorable climate.

Hornbuckle, an associate professor at Iowa State University, thinks of himself as a physical agronomist – a term he coined. It means that he uses physics to study how plants and soil interact with climate. But throw in his expertise in satellite design and data collection, and the work gets even more interesting – interesting enough to land him a role in a European Space Agency project he calls “groundbreaking” and “a perfect fit” for his hodge-podge of interests.

With a youthful face and wiry frame, Hornbuckle has a unique way of understanding how the world works and how to keep it working. He looks like someone who cares about the environment, but like not an activist. Maybe an Eagle Scout. (He dabbled a few years in the scouts, but never reached the rank, he says.). His short sandy-brown hair is parted on the right side, and his digital wristwatch compliments a wardrobe of short-sleeved collared shirts and creased khakis.

“He obviously loves learning new science,” says his cousin, Keri Hornbuckle, head of civil and environmental engineering at the University of Iowa. “…he can discover really interesting things about how water moves between soil, plants and the atmosphere.”

Brian Hornbuckle sees the study of soil and agriculture through the lens of physics as the perfect way to understand the environment in Iowa – a state transformed by decades of heavy farming and widely acknowledged to be the most human-altered land in the Union.

“Especially here in Iowa, it’s pretty clear that what we do on land is going to effect how the atmosphere behaves,” he says. “…we don’t do a lot of management. We plant, and then we cross our fingers and see what happens.”

Hornbuckle says that understanding soil moisture can help make farming more effective and at the same time, improve the quality of the environment.

Listen to Hornbuckle discuss the importance of soil moisture

Looking at soil from space

But to understand the environment on earth, his thoughts are in the cosmos.

Hornbuckle now leads a team in Ames that analyzes data from SMOS (Soil

SMOS in space

This is a realistic illustration of SMOS as it orbits the earth. It sees each spot on earth and measures its soil moisture at least every 2-3 days. - image provided by Brian Hornbuckle, via the European Space Agency.

Moisture and Ocean Salinity), a satellite launched last November, that uses microwaves to measure soil moisture on earth. With the images SMOS sends back, researchers hope to develop real time models to predict how water moves through the landscape - information that could one day help farmers increase crop yields, help communities better prepare for flooding, and give state agencies more information to protect the water quality of rivers, lakes and streams.

Current predictive models are built upon past data points, which can be problematic.

When planning new development, city leaders use maps with the actual measurements from past flood events. The maps mark 100-year and 500-year flood zones.

“The problem is that the entire system – land use, climate and river channels – have changed and will continue to change,” says Hornbuckle.

“Historical data is useful, but not by itself.”

Maps from SMOS are much more up to date. As it orbits, the satellite sees each point on the globe at least every two or three days.

Hornbuckle’s job is to help check the satellite’s work. So on a square kilometer of land just south of Ames – a plot of rotated corn and soy beans – his team performs experiments to verify that measurements from the satellite match what is happening on the ground. The researchers are also making models that translate the raw signal from SMOS to units of soil moisture.

“It’s great to be involved in validation projects like this because that’s where the theoretical science meets the real world,” says Amy Kaleita, an assistant professor in agricultural and biosystems engineering at Iowa State, who helps Hornbuckle monitor soil moisture.

So to make those theories work, Hornbuckle needs to know what’s going on in space and on the ground – a novelty not lost on Keri Hornbuckle.

“Isn’t it cool that the tools of a space scientist can be applied to dirt?” she asks.

Advice from an astronaut

Hornbuckle didn’t dream of becoming an agronomist while growing up in Shenandoah, a small town in Iowa’s southwest corner. Heck, he didn’t know the field existed. But he liked math and science, he says, so he majored in electrical engineering at Brown University, graduating in 1994. After that, Hornbuckle joined the Mississippi Teacher Corps and taught high school physics and chemistry in Clarksdale, Miss.

First image from SMOS

On November 20, 2009, SMOS sent this soil moisture map, its first, back to earth. The job of Hornbuckle's crew is to make sense of it. - image provided by Brian Hornbuckle, via the European Space Agency.

But when he entered the University of Michigan’s doctoral program for electrical engineering, he had yet to explore his curiosity about the environment.

Luckily, his advisor showed him a field that would accommodate all of his interests. Anthony England, a former NASA astronaut who had tried but failed in the 1990s to launch a SMOS-like project called Hydrostar, helped Hornbuckle realize he was a perfect fit for the field.

“The light bulb kind of came on, like boom – this was what I really want to do,” Hornbuckle says.

Understanding the landscape

Hornbuckle says he loves studying the Iowa environment, but he worries about the state’s future.

“There's a need for people to understand how changes in climate as well as
the increased pressure to produce both food and fuel will affect Iowa's
agricultural systems," says Hornbuckle.

“These changes will have consequences for the water cycle - how often and to what degree we experience heavy rain as well as periods of drought, and how much runoff makes it to rivers, lakes and streams."

Environmental experts say we have already seen those consequences in the form of more extreme weather – like flooding.

The past 36 months have been the wettest in Iowa’s 136 years of record keeping, bringing floods that have driven thousands of people from their homes and caused millions of dollars worth of damage across the state.

And last summer, 57 of Iowa’s 99 counties were declared disaster zones.

But still, Hornbuckle is optimistic about what his research will yield, and his cousin believes in him too.

“He’s an awesome scientist,” says Keri Hornbuckle.