Monday , April 13, 2015 - 9:57 AM
OGDEN — The Weber State clock tower finished chiming at 11 a.m. just after the aerostat made its first float in the outside air, which felt unusually warm for Feb. 1.
Hovering above students’ heads, the aerostat looked a bit like a miniature ventricular cloud with a gossamer half-skirt, or a brilliantly white and graceful alien spaceship with an inverted sail.
“Fire up the atmo-sniffer,” said John Sohl, physics professor and HARBOR adviser, wearing a purple Patagonia jacket over a Weber-purple polo shirt. “If we can’t lift that thing, this whole deal is for naught.”
The scientific community tends to have plenty of distinctive terms, monikers and acronyms. An “aerostat” is a fancy name for a balloon. The “atmo-sniffer” is an innovative device, created by Sohl and his students, to measure the muck in Utah’s inversion-prone air up to 1,000 feet. “HARBOR” stands for High Altitude Reconnaissance Balloon for Outreach and Research, a team of students working with Sohl to collect groundbreaking new data on Utah’s inversions.
“We’re not really sure what we’re going to find,” Sohl said. “We do know from a few preliminary measurements … (that) when you look at the haze layer, it looks like this uniform ‘ick’ layer, but it’s not uniform. So how is it mixing? What’s going on in there?”
Sohl is the adviser for the HARBOR club, which has flown high-altitude weather balloons for around seven years. The club fluctuates between 15-20 members, and is open to local students from junior high up to college seniors.
With the help of those students, Sohl is working with the Utah Division of Air Quality to get a better grip on the dynamics of inversions along the Wasatch Front, like how pollutants and particles mix in the atmosphere.
“We have excellent air monitoring systems on the ground, run by the Utah Division of Air Quality. We have a handful of measurements made over the years by the University of Utah Atmospheric Science Program, but not very much,” Sohl said. “So we are trying to fill that data in and better understand what is happening to our air.”
In 2014, the Utah Legislature granted DAQ $1 million to fund new research on the state’s air problems. Sohl received $13,000 for his idea of measuring gasses and pollutants up through the air column.
The idea is to have a balloon float a miniature air-monitoring station into the thick of the dirty air so they can collect real-time measurements. During an inversion, they’ll take measurements at the Weber State campus, then haul the system to downtown Ogden to collect a measurement at the ground-based DAQ station near 32nd Street and Grant Avenue.
“DAQ has a lot of data; they’re very smart people, but there’s data that’s just missing and we have the capability for,” Sohl said.
As simple as that sounds, it took a bundle of imaginative thinking, like finding a balloon that deploys quickly and stays anchored. Or developing an air data device that’s light enough to be lifted by a helium-filled balloon. Or coordinating an assortment of students, with their varying schedules, so they can hammer together a storable and movable monitoring system, complete with a 200-pound winch and two helium tanks.
Traditional weather balloons are meant to drift along atmospheric currents, rising until they pop. The HARBOR air monitoring project, however, needs stationary air samples and a balloon that’s not going to wander into nearby buildings or in-flight aircraft. But keeping a high-altitude balloon in one place presents a unique set of problems.
“We’ve been flying balloons for seven years now, and that includes a few tethered flights, so you quickly discover that a tethered flight with any wind is utter misery,” Sohl said.
Tether those balloons, and a light breeze will tug them sideways or make them bob so they can’t hover at a useful altitude. With stronger gusts, tethered balloons literally start to get ripped apart.
With a little networking, however, Sohl found a unique type of aerostat, called the “Kingfisher” — named for a type of bird known for its uncanny ability to hover.
The aerostat’s oblong shape and fabric wing help it stay moored and stable, so it can keep hovering under high-wind conditions.
“This thing will go to a 50-plus mile per hour wind and still function,” Sohl said.
The next step was developing that mini-monitoring station meant for the sky. Sohl worked with one of his students, recent graduate Michael Petersen, to develop a patent-pending atmo-sniffing device that endures the harsh conditions found at altitude.
“Pretty much all gas sensors work in ambient temperature and pressure. This system is designed to be calibrated from ground level to the very edge of space,” Sohl said. “So we have the advantage of being able to function in pretty much any hostile environment where your normal devices cannot.”
They made their atmo-sniffer mostly from commercially available parts. What they couldn’t find, they made, using a 3D printer.
The device needs to be tough and functional, but it also needs to be light, otherwise the aerostat won’t float. The team has it down to 1,400 grams, around the same weight as a brick. It’s still just a little too heavy.
“We need to reduce the mass of the system by another 500 grams; at this point we are counting grams,” Sohl said.
Naturally, it takes more than a slick new balloon and tiny air laboratory to pull off an ambitious project.
Sohl admitted that when he presents the aerostat project at conferences or explains it to other researchers, his peers are often surprised he’s not using a team of graduate students, but Weber State doesn’t have any science graduate programs.
“We’ve got high school students and undergraduates exclusively running the program, and that means you don’t have the flexibility you’d normally have,” Sohl said. “Plus, we’re designing it with all-undergrad design methods rather than having people who are, essentially, already professionals doing all your work for you.”
Sohl’s students might not be as seasoned, but they do bring enthusiasm. For the aerostat project, they often give up weekends and worked long hours so they could build the trailer, anchors and supports so the balloon can be quickly deployed.
For days, it was a process of chalkboard diagrams and calculations, assembling, disassembling, inflating, deflating, testing the weight, testing the winch, then, finally, moving it all outside. Sohl called it “controlled chaos,” but that’s part of his teaching philosophy.
“My job is to empower the students to accomplish what they’d like to accomplish. So I give them resources, the education, the structure to be able to do that,” he said. “The students’ job is to make it happen.”
That learning process is prone to bumps and delays. The aerostat’s first test flight, back on that warm February day, found the atmo-sniffer was just a bit too heavy. It also had a hard time transmitting data to the ground.
“We were also happy to see an illegally flying airplane; that gives us a heads up that people do fly at altitudes they’re not supposed to,” Sohl said.
The project’s biggest obstacle this year, however, came from Mother Nature.
“Without any snow on the ground this particular winter, we’ve not had a powerful inversion,” Sohl said. “We’ve had some ick air and we’ve had some modest inversions, but we haven’t had a deep stinking inversion where you’re just choking down in the valley, because we haven’t had any snow on the ground.”
That doesn’t mean the aerostat project is deflated until next winter. The team will continue to trim grams off its sampling system, improve the downlink system and refine the deployment.
Locals might also catch a glimpse of the curiously shaped balloon in Utah skies this summer.
“We’re going to be measuring ozone evolution over the Great Salt Lake, and other areas, using the aerostat,” Sohl said. “We’ll be parking the system on a buoy, of all things, in the middle of the lake.”
As the HARBOR club labors on to perfect the aerostat system, complete with its purple hauling trailer and purple casing for the atmo-sniffer, Sohl has plenty of pride in the program and its team.
“I’ve always had faith my students would do cool stuff, and they are,” he said. “I have no fears that they’re not going to be able to pull this off.”
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