A research balloon that the Montana Space Grant Consortium at Montana State University launched last month in preparation for monitoring a total solar eclipse in 2017 provided learning opportunities – just not of the sort that the researchers originally expected.
The plastic zero-pressure balloon – which carried GPS devices, a small computer, radios and cameras for information gathering – was intended to fly to an area near Ryegate, about 60 miles away from its launch site near Big Timber. Instead, it landed approximately 1,130 miles away on an island in the middle of a lake in Manitoba.
However, in order for the balloon to descend from the atmosphere back to the ground once its flight was complete, it needed some help.
Zero-pressure balloons are large – approximately 42 feet tall, with a volume of 10,000 cubic feet – and are partially filled with helium at launch, Knighton said. As the balloon ascends, the helium expands until it fills the entire volume of the balloon, at which point any excess gas vents out the bottom, stopping the balloon’s ascent. The balloon typically rises to about 83,000 feet during flight, which classifies it as a high-altitude balloon.
“The balloon just floats like a boat on the ocean,” Knighton explained. “There really isn’t any reason for the balloon to want to come down at that point unless you actually make it come down.”
So, the balloon is equipped with a razor-like blade and a motor that can be activated via a computer to cut a line between the balloon and all that it is carrying – also called its “payload.” When the line is cut, it triggers the balloon to descend.
“This essentially makes the top of the balloon the bottom. Helium escapes, and everything, the balloon and its payload, comes down together,” Knighton said.
But in the case of the balloon that launched July 22, the motor that held the razor blade had shifted inside of the housing on which it was mounted, Knighton said. It couldn’t make the cut. And since it couldn’t make the cut, the balloon kept going.
“What was supposed to be a three-hour flight took 32 hours to complete,” Knighton said. “And, the balloon traveled approximately 1,130 miles, instead of about 60.”
Rather than coming down near Ryegate, the balloon headed west. The group monitored its path via the GPS devices. The balloon circled in the air just east of Missoula for about an hour, Knighton said, and then eventually headed north and east and entered Canada, where its GPS went offline.
Knighton reported the missing balloon to Canadian authorities and began making projections about where it would land.
“When we lost contact with it, the balloon was at 43,000 feet,” Knighton said. “If it was going to sea level, it would take 43,000 seconds. My initial projection had it landing in Saskatchewan, northeast of Regina, but it didn’t descend that quickly.”
Instead, the balloon landed in the water in the middle of Manitoba's Lake Winnipeg, Knighton said. At that point, the GPS device turned back on, allowing Knighton to again track it.
“As soon as the payload hit the water, the balloon became buoyant again. Half of our experiment hovered over the water,” he said. And, as it hovered, the balloon continued on to Nut Island, an island in Lake Winnipeg.
“The (GPS) device continued to tell us it was on that island, so we knew that the flight had ended, and exactly where it was,” Knighton said. “Our next challenge was determining what we were going to do to retrieve it.”
With the help of contacts at Google, which also has a ballooning program, Knighton chartered a boat on Lake Winnipeg.
He set off for Nut Island on July 26, four days after the balloon had launched. It took about two hours by boat to reach the island. About a mile away, he saw a light from the balloon’s reflection as it waved in the wind, Knighton said. The balloon was found draped around a large cottonwood tree on the island.
“I was able to extract the balloon from the foliage and retrieve all of the equipment, which was in remarkably good condition considering the payload had gone water skiing on Lake Winnipeg,” Knighton said.
“We were happy to be able to look at everything and recover additional data,” he added. “We got memory cards from the cameras that we were able to retrieve.”
Knighton called it a successful outcome and said the entire experience will help the BOREALIS group plan for possible challenges when it launches research balloons in the future.
“For me, this makes you sit back and reevaluate what you did and how quickly you did it,” he said. “This (razor blade termination mechanism) was a system we had used for the last three or four years. We had successfully terminated many flights with it. But this showed us the worst-case scenario, so we’ll be better able to handle challenges like this in the future.
“It was an awesome learning experience, and we met some very wonderful people,” he added.
The Montana Space Grant Consortium will lead a national network of college students to monitor an upcoming total solar eclipse with high-altitude balloons. More than 50 schools from Puerto Rico to Alaska have signed up so far to be involved. The eclipse will be visible across the United States on Aug. 21, 2017.
Contact: Berk Knighton, (406) 994-5419 or firstname.lastname@example.org