Now that hundreds of hours of work by a group of Duke University engineering students has produced the school’s first high-altitude balloon launch and some important atmospheric data, the plan is to aim even higher.
Meanwhile, they’re reflecting on the accomplishment by savoring the project’s successes and learning from its challenges. “I think the most exciting part for me was the idea of something I had helped to build floating at the edge of the stratosphere, looking out at the world beneath it and recording everything about its experience,” said sophomore Jack Siman of Charlotte, one of the project managers.
Added fellow sophomore and team member Josh Furth: “It was exhilarating and nerve-wracking at the same time.” They were among the 15 students participating as part of a class – Applied Engineering Design Skills – taught and led by professors Walter Neal Simmons and Greg Twiss.
The project was a lesson in engineering teamwork and the interconnectedness of disciplines ranging from electronics to mechanical design to physics to chemistry. Beginning in mid-October, the students broke into groups, one for each balloon, and spent more than 500 hours researching and building the equipment connected with the simultaneous launch on Dec. 6 in Hillsborough.
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Though only one of the three attached GoPro cameras kept recording on the way to 120,000-foot heights in one of the balloons, they yielded atmospheric data, available at www.dukeballoon.com.
Siman said the information includes a temperature profile of the atmosphere “to the top of the stratosphere, which could be compared with past samples to determine if Earth temperatures are increasing and if so, where they might be increasing apart from the surface and the impact that that could have on global warming.
“We also collected ozone data which shows how the ozone levels increase in the stratosphere, a confirmation of the existence of the ozone layer but also a current reading of the concentration of the gas. You can also compare the acceleration and altitude graphs and see where the highest winds are – the jet stream at the edge of the troposphere.”
Building and materials
Other students working on the project were Uzo Ayogu, Chase Beason, Kyle Dhindsa, Stan Fox, Sachin Govil, Connor Guest, Ann Marie Guzzi, Raya Islam, Tyler King, Henry Quach, Keith Sobb and Elijah Weinreb. Siman said that after the students defined their roles, designed the payloads, ordered materials and researched FAA rules on high-altitude balloons, some intense building began.
“Once things started to arrive, the payload and electronics teams split off to construct the housing and wire the sensors,” Simon said. “Our payload consisted of a Styrofoam cooler reinforced with a strong yet lightweight aluminum and plastic frame, which we custom engineered for the project. This would ensure the payload could survive a high-speed impact with the ground but stay under the 6-lb. limit set by the FAA for the type of balloon that we were launching.
“The electronics onboard consisted of temperature, pressure, ambient light and ozone sensors, as well as an accelerometer and two independent tracking systems. All of our team members were mechanical engineers, so the electronics team spent a lot of time assembling, soldering, coding and debugging the system. We used an Arduino to process and store our sensor data, but a HAM radio and a Raspberry Pi in the Sky provided two independent tracking systems should one fail.”
Despite this methodical preparation – which also included a test launch on Duke’s Durham campus – the students were reminded that nature has a mind of its own. The excitement of the launch quickly gave way to curiosity and concern during the two-plus hours the balloons were aloft.
“As soon as we launched we sent out two chase cars so that we could be in the area when the balloons landed,” Siman said. “There is software online that takes real-time weather data and predicts landing spots for high-altitude balloons.”
Past, future challenges
But maintaining constant communication was difficult, Furth noted. “The distances are great, to say the least, and so to maintain communication with the payload throughout that time was optimistic,” said the 19-year-old from Stamford, Conn. As for why two of the cameras stopped working: “We think it had to do with either the pressure or the temperature, and that the cameras just got too cold even with the heating elements and insulation we provided.”
Both balloons burst – which was expected due to the major atmospheric changes at such high levels – but only one successfully deployed a parachute with the data recorder. It landed about 70 miles away, in Rocky Point, Furth said.
The team is looking forward to more challenges in future launches. “The hope would be to look at the data and see what sorts of anomalies or interesting characteristics there are,” Furth said. “We noticed some things about the ambient light sensor relative to the orientation and rotational movement of the payload.”
Also: “Now that we have the experience of getting the balloons and payloads up to such extreme altitudes, we could do a more complicated payload at that altitude which is almost hypoxic or anaerobic (virtually no oxygen present). So we could simulate certain things that might happen in certain parts of our bodies, chemical processes that occur without oxygen in that extreme environment.”
Not full of hot air
Both high-altitude balloons and hot air balloons are referred to as HABs. But they aren’t the same thing.
Gondolas suspended from hot air balloons often carry people aloft. These balloons work by heating the air inside the cloth envelopes balloon; their world-record height is 65,000 feet.
High-altitude balloons are unmanned objects often used as weather balloons, as with the Duke project. They use gas, usually helium or hydrogen, with average heights of 60,000 to 120,000 feet – the latter “three to four times the altitude that aircraft normally fly,” Furth said.