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A Small Step for Physics, A Giant Leap for Student

By Abbey Becker

Greg Clarke at NASA

Photo courtesy of Greg Clarke

When Greg Clarke, BS physics ’12, was growing up, he wanted to be an astronaut. While he’s sidelined that specific wish, he’s made his dream of working for NASA come true—since the summer after his sophomore year, he has interned with emeritus physics professor Richard Kay in the Laser Remote Sensing Laboratory at NASA’s Goddard Space Flight Center.

As a sophomore, Clarke was having trouble finding opportunities for research within his major. “It was hard to get my foot in the door of physics internships,” he says. “But this opportunity was recommended to me, and it went from a summer internship to a year-round thing.”

In the lab, Clarke works alongside Kay, Professor Demetrios Poulios, and several NASA civil servants on the engineering of lasers for Light Detection and Ranging (LIDAR) purposes. “LIDAR is kind of like sonar, in the sense that sonar is shooting out sound waves and looking at them as they come back,” Clarke explains. “LIDAR is shooting out lasers and analyzing the return signal to make topographical maps of outer space.”

Specifically, a pulse of light is shot out from a fixed location. It goes into space, hits a target, and when it comes back, scientists can look at how long it took to go into space and come back. Since the speed of light is a known constant, scientists are able to tell how far away an object is. “Say you have a mountain and a valley,” says Clarke. “It’s going to take a lot less time for the pulse to come back from the mountain than from the valley.”

In the past, LIDAR was used to help map the surface of the moon. “Before, when we first went to the moon, the astronauts were sitting there with a joystick, trying to land in the perfect spot because they had no idea what the actual surface of the moon looked like,” says Clarke. Much of Venus’s topography is unknown, and one of the lab’s proposed missions is to use LIDAR to map its surface.

LIDAR can also show climate change over time. “There are a lot of missions where they take the topographical information of the polar caps, and then they can see the melting of the ice,” explains Clarke. “If it takes longer and longer for a pulse of light to come back from the ice caps over time, it means they’re probably melting.” Biomass information, like the changes in vegetation on Earth, can show how the Earth is being affected in a very precise way.

The team’s next proposal is for a mission to put lasers on the International Space Station. It’s not easy to get a dedicated satellite for projects, but oftentimes other satellites have room for addition projects.

Working with Kay, a former chair of the AU Department of Physics, has been especially beneficial to Clarke. “He’s got a wealth of knowledge,” he says. “The field of lasers is a newer field, and he’s been in it almost from the beginning. It’s just great to see how much he knows.”

While the particular subject is new for Clarke, the techniques he’s using at his internship are not. “A lot of what I learn in the classroom is the basics, and then at the internship, it’s how the basics are applied,” he says. “My work in the lab lets me see these concepts in a broader sense. It reinforces everything into the practical world.”