The United States experienced a total solar eclipse on 21st August 2017 for the first time since 1918, with the path of totality across the entire continental United States. About 20 million people (a conservative estimate) watched from the path, and according to NASA, 40 million people watched the live eclipse broadcast on its website and social media.
DURING the solar eclipse, how did the LIVE video and images of the moon blocking the sun and the moon’s shadow hurtling across the earth reach NASA’s website? They came from balloons, outfitted with camera payloads, soaring near the edge of space. This was the first time that live streaming of an eclipse was accomplished with network coverage across a continent. One of the impressive things about NASA’s Eclipse Balloon Project was that, the 55 teams who accomplished this challenging task consisted of students from universities across the United States, and there were also ten high school teams. All teams were led by Dr. Angela Des Jardins director of the Montana Space Grant Consortium.
“It’s pretty amazing that with a low watt radio transmitter in a shoebox-size payload, we were able to stream down to antennas on the ground and then push it to the Internet. So, having that connection with the antenna on the ground and to receive the signal from the balloon– that’s a huge challenge that our teams had been practicing with for quite some time,” said Dr. Des Jardins in an interview with LTA-Flight Magazine. The teams had to ensure that the balloon’s equipment / payload did not exceed twelve pounds, which was also an FAA requirement. “The overall project was very successful as we had expected. There were so many different things that came into play to do the live streaming, and teams had various degrees of results.”
Using Raspberry Pi and Arduino computers that allow sophisticated experiments at relatively low cost, balloons became a great accessible platform for hundreds of students who conducted high-altitude balloon flights and experiments from over 25 locations across the total eclipse path, from Oregon to South Carolina.
The idea to live stream video and images of the eclipse came to Dr. Des Jardins in 2013, who made it her mission. “I set out to convince NASA to support it and get the grant,” she said. “I grew it up in a very grassroots way, and the support that we had from NASA education and NASA Science Mission Directorate was hugely important in that.”
In preparation for the rare astronomical event, the Montana Space Grant Consortium has led students from across the US, since 2014, on a mission to capture live images from the edge of space, using high-altitude balloons.
Trevor Gahl, who started his Ph.D. in electrical and computer engineering at Montana State University (MSU) in 2017, joined the project as an undergraduate student. “It was the aspect of being able to apply computer and electrical engineering and the knowledge from basic sciences to contribute to the embedded systems in high-altitude ballooning was what interested me,” says Gahl.
In the four years that the students have been working on the project, they accomplished about twenty test flights. Gahl’s MSU team had 12 members and they worked on the hardware of the ground station. Their team was the focal point of a nationwide project leading up to the day of the eclipse. So Gahl’s biggest challenge was time management. “We would get e-mails and phone calls from teams across the country that were also using our systems. We had to support, assist, and troubleshoot any problems they had, and we also had to get our project to a stage at which it would operate because this was something new that we were doing–streaming live video from balloon cameras during an eclipse. And we were going to have teams along the entire eclipse path from Oregon to South Carolina that would be sending live video of the shadow of the moon passing over the earth.”
For more than a year, Gahl and his team worked on the implementation of the automatic track algorithm that would track the balloon throughout the duration of the flight.
Gahl and his team reached Rexburg, Idaho, on Saturday and set up their camp and equipment. On Sunday they tested everything and did a dry run. “We started at 5 o’clock in the morning on Monday to make sure everything was going to be ready to get our balloons into the air in time.”
Flight Director Berk Knighton had estimated the typical ascent rate at about 1,100 feet per minute, so each balloon would rise to 50,000 feet within an hour. The fact that the totality was only 2 ½ minutes long, meant only a 10-minute window for the launch, to allow the balloons to rise to the target altitude (60-80,000 feet) and not any higher, as that would have increased the risk of bursting.
To be in the correct place for the eclipse and to launch their balloons in the stratosphere, many teams found themselves in the middle of nowhere and had to make sure that they had good Internet connections. “That’s difficult because without a hard Internet connection we weren’t able to rely either on self-phone jet packs or hotspots, because we knew and anticipated that the cell phone networks would be overloaded,” says Dr. Des Jardins. “And even places where the teams thought they were going to have really good Internet, media folks showed up and stole their Internet connections, so to varying degrees people had good streaming video.”
Gahl and his team had some equipment problem during launch. “There was more turbulence than we expected and then things came unplugged. We were able to get a video and some still images but some of our other stuff didn’t quite function properly. We’re still looking into the hardware failures that we found,” he said, adding that many teams’ equipment worked well. “That was awesome to see that all of our hard work had been able to pay off for all these other students nationwide who got involved with it. They were able to get data,” he said.
To get all round images and videos, the payloads carried different imaging systems. The still image system used a DSLR Nikon camera and other ones were Raspberry Pi and Pi Camera whose tilt could be adjusted to look up or down. For the multiplexer video system, they had a series of eight cameras going around the perimeter of the payload. And these could remotely be pointed to cardinal directions like north, northeast, south, and so forth. It also had a chip inside the actual measurement unit that would detect what direction the payloads were facing, and it would choose the camera that was closest to that direction.
On eclipse day, as the moon made first contact with the sun, the temperature started to drop. And as the air cooled significantly during totality, some low-pressure balloons dropped from 80,000 to 50,000 feet, and rose up again after the sun came into view. The standard or sounding balloons did not experience much altitude change.
Besides getting live video and images of the eclipse, many teams conducted various experiments, and NASA and MSU presented early results of the Eclipse Ballooning Project on 11th December at the American Geophysical Union’s conference. The difference in images of the Earth and atmosphere taken from high-altitude balloons on an eclipse day and on a non-eclipse day is striking. “On non-eclipse day, the horizon is pretty brightly lit, and you can see fantastic things on the ground but also get a really good feel for the layers of the atmosphere, which is really interesting. During the eclipse, it’s just amazing, because you can see the dark shadow coming in, and, then when the balloon is in the shadow, you can see a kind of 360-degree sunset effect. So, you have the dark area and then the bright area where the shadow is, and you can’t see anything on the ground because it’s dark. So, it’s like this gigantic black hole kind of effect,” said Des Jardins.
When taken from above 80,000 feet, the images also show some curvature of the Earth.
According to Dr. Des Jardins, balloons are an inexpensive and stable platform to get fantastic footage and images and also to do science experiments, depending on the type of experiments. “Obviously, from very expensive satellites, you can see something, but this is a way to get hands-on experience yourself, and for most people doing satellite or some other high-tech platform is completely out of reach,” she says.
Gahl adds: “The planes cannot get this high. The balloons go up to around 90,000 feet which is the lower stratosphere. And so, we get a much wider viewing angle or range that we can take pictures from.”
He cites another potential project at MSU that will use balloons and camera payloads to do imaging of thunder storms. “We’ll be able to fly above the clouds, and we can do a lot of that stuff that the planes can’t necessarily do. They can get up above clouds but not stay in one spot like a balloon can. You know a couple of weeks ago, we could have been able to image all the fires in Montana and see how they were progressing. So, it’s a very stable imaging system for a relatively low cost.”
Randy Larimer, deputy director of Montana Space Grant Consortium notes that it was incredibly rewarding to watch the students grow in technical skills, social skills, and business skills while working on the project. And though the challenge was daunting at times, the students succeeded in accomplishing the mission and in engaging the public during this awe-inspiring celestial event.
Click the link below to watch videos that were streamed live on eclipse day.
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