Shadow Bandits Ready for Eclipse Day

Multitudes are taking to the highways this week to make their way to prime viewing locations for what is being billed as the Great American Eclipse.

Among them will be a team of Pitt students, faculty and staff ready to help NASA livestream the cosmic event and conduct research during what stands to be the most-viewed solar eclipse ever. The group leaves Aug. 18 for its assigned spot in Tennessee.

The group, called the Pitt Shadow Bandits, is part of a network of more than 50 teams of college and high school students that plan to send cameras and research equipment aloft as part of a nationwide NASA Eclipse Ballooning Project.

On Aug. 21, for the first time in 99 years, a total solar eclipse will cross the entire North American continent. Only a partial eclipse will be seen in Pittsburgh, but a total eclipse — in which the moon completely blocks the sun — will traverse 14 states from Oregon to South Carolina.

Solar eclipses are not especially rare — typically there are two total eclipses every three years — but they often occur over oceans or remote regions where few can see them, said Dave Turnshek, director of Pitt’s Allegheny Observatory.

This one is different: Some 200 million people — nearly two-thirds of the nation’s population — live within a day’s drive of the 70-mile-wide path of totality.

“This is a special opportunity for astronomy on this one day,” Turnshek said. The teams will launch high-altitude balloons from across the path of totality to study the eclipse and — for the first time ever — stream photos and live video from near-space as the moon’s shadow races across the nation.

Pitt’s Shadow Bandits also plan to study the phenomenon known as shadow bands — wavering bands of light and darkness that appear on the ground around the time of a total eclipse.

It’s theorized, but unproven, that shadow bands are caused by atmospheric turbulence that is invisible in normal daylight, said faculty member Russell Clark of the Department of Physics and Astronomy.

The team will compare observations from the light sensors on its balloon with observations on the ground. If shadow bands are atmospheric in nature, they won’t be seen from the balloon’s vantage point above most of the earth’s atmosphere, said Clark.

The Shadow Bandits have been preparing for more than a year: planning their experiments, programming and re-programming the tiny microcomputers, adjusting their cameras, conducting test flights from the Allegheny Observatory and perfecting their timing so their equipment will be in just the right spot — some 80,000 to 100,000 feet above the earth — at just the right time on eclipse day.

From their launch site just north of Springfield, Tennessee, the sun will be completely obscured for just 2 minutes, 37 seconds, beginning at 1:26 p.m. CDT (2:26 p.m. in Pittsburgh).

The Shadow Bandits’ eyes already are on the skies. This eclipse will be a first for the students. The last total solar eclipse visible in the contiguous United States occurred in 1979, well before they were born.

“Regardless of conditions on the ground, the Shadow Bandits’ research will take off,” Turnshek says. “It’s always sunny above the clouds.”

Physics and astronomy faculty member Sandhya Rao credited Turnshek and Clark with setting a low-key tone that’s conducive to learning and supportive of the trial and error that’s inherent in experimentation and discovery. 

“Every test has positives and negatives. Each flight, there are things that can be improved,” Rao said.

With confidence, the students suggest modifications and solutions as the team analyzes its successes and failures. “They’re not timid,” Rao said, noting that none of the students are astronomers. “They have some very good ideas. It’s really a give and take.”

The Shadow Bandits: Grace Chu and Janvi Madhani, undergraduates in physics and astronomy; engineering students Sinjon Bartel and Carlos Vazquez; 2017 engineering alumnus Marshall Hartman; and Aimee Everett, an environmental science and nonfiction writing major; have each found a niche on the team.

Hartman and Bartel, the first students to join the team, traveled to Montana in July 2016 with Rao, Turnshek and observatory technician Lou Coban for an initial training workshop where they met other schools’ teams and received basic hardware and code.

They’ve continued to work mostly with the basic payload, coding the computers that control communications, cameras and video streaming to ensure that data is being transmitted to the ground and to the location-tracking satellites.   

With Vazquez, they’ve modified the original design to ready the payload for eclipse day. Vazquez has focused on ensuring that the computer-controlled cameras are ready to capture the eclipse. It’s tricky to sync multiple cameras — some aimed at darkness, others at glaring sun — that all the while are spinning and bouncing beneath the balloon.

Chu and Madhani have focused mainly on the photodiode arrays — light sensors that will be used to test the shadow bands theory. With Vazquez, they designed and built a shadow band simulator to ensure that their photodiodes would indeed detect the fluctuations in light intensity.

“We needed something really sensitive,” said Madhani. The arrays also needed to be lightweight and tough enough to withstand pressure changes and the frigid upper atmosphere. “Most components aren’t designed for -40 Celsius,” said Chu.

They’ve literally weighed every option as they built the payload. Every gram counts when the entire string — including seven microcomputers, 13 cameras, two modems and the photodiode arrays — must remain under the Federal Aviation Administration’s limit of 12 pounds.

Everett has been analyzing weather data to predict the balloon’s flight path and expected landing location. By her calculations, the team’s payload will parachute to the ground 10-20 miles from its Tennessee launch site.

Team members already have had the opportunity to highlight their work. “The project was a great selling point to discuss in job interviews,” said Hartman, who graduated in the spring with a degree in mechanical engineering and now works in Wisconsin for health care software firm Epic. His success in the job market comes with a downside: He won't be able to join the team in Tennessee on eclipse day.

Chu, Madhani and Vazquez were featured presenters at Duquesne University’s summer undergraduate research symposium. The Shadow Bandits’ project was among seven highlighted at the annual regional event.

“This is a huge learning experience for our students,” said Rao. “They’re learning how science is done, how experimental work is done. It’s not a straight line. You learn from things that go wrong.

“You learn to design a set of questions to get the answers you seek. You learn to solve problems, to frame questions.

“Aside from the fun of seeing a solar eclipse, these are valuable life lessons.”

Safe Eclipse Viewing

Viewers need to protect their eyes to view the eclipse, said Deepinder Dhaliwal, professor of ophthalmology at the School of Medicine and director of refractive surgery at UPMC Eye Center.

”When looking at the sun, the eye takes in light through a lens that focuses it onto a delicate structure in the back of the eye known as the retina,” Dhaliwal said. “When sunlight becomes concentrated on the retina, it can result in a painless burn” resulting in irreversible blind spots.

Learn more in this video and blog post featuring Dhaliwal's eclipse-watching advice.

In Pittsburgh, a partial eclipse will begin at 1:10 p.m. and end at 3:55 p.m. on Monday, Aug. 21. The moon will cover 81 percent of the sun’s disk at 2:35 p.m. 

Watching at Pitt

• Pitt Shadow Bandits and NASA eclipse livestream, 1-4 p.m. in the Thornburgh Room in Hillman Library.
• Eclipse viewing party, 2-3 p.m. on the Hillman Library Plaza hosted by the Division of Student Affairs and the University Library System, weather permitting. Viewing glasses are available at library service desks.

— Kimberly Barlow