Montana State University

Electrical engineering grad students earn prestigious NASA fellowships

June 13, 2008 -- By Michael Becker, MSU News Service

MSU graduate students Amin Nehrir (left) and David Hoffman stand in front of a green laser beam they are using to study the composition of earth's atmosphere. (MSU Photo by Kelly Gorham)   High-Res Available

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MSU News Service
Tel: (406) 994-4571
Bozeman - A pair of Montana State University graduate students will have the chance to work with some of NASA's top scientists in laser technology, thanks to a prestigious research fellowship awarded in May.

David Hoffman and Amin Nehrir, master's students in electrical engineering, both received $30,000 fellowships through NASA's Graduate Student Researchers Program.

In addition to the money, which covers educational expenses, Hoffman and Nehrir will each spend a portion of the coming year as interns at NASA's Langley Research Center in Hampton, Va., one of the oldest and most famed aviation and space laboratories in the world.

Only 171 students around the country received the fellowships, said Linda Rodgers, manager of the fellowship program for NASA. Rodgers said it was exceptional for two students from a mid-sized university like MSU to win fellowships, let alone two students in the same department.

Hoffman and Nehrir work with lidar, which stands for light detection and ranging. Their work involves sending a pulse of laser light into the sky and letting it bounce off the particles suspended in the air. By measuring the amount of light that bounces back, how that light is scattered and the time it takes to return, scientists can learn about the composition of the lower atmosphere.

It's work that has fascinated both students since their sophomore years at MSU, when they began working in electrical engineering professor Kevin Repasky's lab.

Originally from Utah, Hoffman first took an interest in lasers after seeing the mysterious bolt of green light that can sometimes shoots into the night sky from campus. Those bolts of light - lidar experiments originating at Cobliegh Hall - drew Hoffman's attention.

"One of my roommates called and saw that and said he thought aliens were invading or something like that," Hoffman said. "That was the first time I started reading up on lidar and learning what it was about."

Hoffman just finished his master's thesis, for which he built a two-color lidar. Now he is building an optical filter that will allow lidar systems to differentiate between those airborne particles and atmospheric molecules - indentifying and quantifying dust, pollen, pollution and the like.

Nehrir, a Bozeman native, never thought he'd work with lasers on a daily basis. He fell into lasers and lidar after taking undergraduate electrical engineering classes. Now Nehrir is building a differential absorption lidar system that will detect the amount and distribution of water vapor in the atmosphere.

Both students' work could one day help scientists study the climate and could help take MSU from the instrument-building phase into atmospheric research, said Repasky, who advises both students.

"They're starting to build instruments that are up there with other instruments being built around the world," he said.

Those instruments could be used to help understand how clouds form around different types of airborne particles, which affects the entire water cycle, from the types of clouds that form to the amount of precipitation expected from them.

"These connections we're making in NASA are really nice steps to take because it allows us to take our expertise in instrument development and get outside help in moving into this atmospheric science," he said, noting that the connection to NASA began through the Montana Space Grant Consortium, which funded the initial projects and provided student support.

NASA is particularly interested in the small, 2-by-4-by-4-foot lidar assemblies MSU is building. By comparison, some lidars are large enough to fill an entire 40-foot cargo container, Repasky said.

He added that MSU's lidars are also relatively inexpensive, costing less than $100,000. Larger and more complicated assemblies cost hundreds of thousands of dollars.

Smaller, cheaper lasers like MSU's could one day be used in experiments on earth and in space, Repasky said.

Both students agreed that the work, which often involves late nights spent shooting laser beams through a roof port in Cobleigh Hall, can be frustrating at times, especially when things go wrong for weeks on end. However, learning from those failures - and the rare nights when everything goes just right - keep them coming back to the lab.

"It's just knowing that no one's made that measurement yet, and if you make it, there might be a major breakthrough," Nehrir said. "It's just the curiosity I guess. That, and it's cool to work with lasers."

For related stories see:

MSU researchers build lasers for NASA climate change, Feb. 2, 2007

NASA awards MSU student $24,000 to study water vapor, May 13, 2004

MSU professor's research on bacteria's role in precipitation cycle published
by "Science," Feb. 29, 2008

Contact: Amin Nehrir at; David Hoffman at; Kevin Repasky at (406) 994-6082 or