About a dozen weather balloons carrying high-definition cameras and science experiments took to the skies this month as part of an unprecedented study of auroras.
Launched from near Fairbanks, Alaska, the balloons were designed to be a cost-effective way to study the light shows, which are created when charged solar particles interact with Earth's atmosphere.
"We're trying to image the auroras from an altitude of about 100,000 feet [30 kilometers]," said project founder Benjamin Longmier, a physicist with the Ad Astra Rocket Company and an adjunct member of the physics department at the University of Houston in Texas.
"We knew going into this that this was going to be a very difficult feat, but we were attacking it from quite a few engineering and technology-development approaches."
Over the span of about a week, project members attached sensors, science experiments, and modified GoPro cameras to latex weather balloons and released them in central Alaska, where auroras are visible nearly year-round.
In addition to new HD shots of auroras, the results of this expedition might help the team design a fleet of low-cost aurora probes. Unlike Project Aether's weather balloons, Longmier said, "these small spacecraft would fly directly through the aurora during each orbital pass."
Cost-Cutting Aurora Science
Auroras, also known as the northern and southern lights, are ethereal light shows created when solar plasma—a mix of superheated charged particles—gets trapped in our planet's magnetic environment and funneled toward the Poles.
When the solar particles collide with molecules in Earth's atmosphere, they transfer extra energy that gets released as light.
NASA and other organizations have flown sensors near auroras before. But with Project Aether, Longmier hopes to do the work for a fraction of the cost.
"NASA has had this paradigm in the past of developing million-dollar balloons that can carry two-ton payloads up to 100,000 feet [30,500 meters] and stay there for a week," Longmier said.
"They're very capable and good balloons, but it's just one set of measurements in time and space.
"The paradigm that we're opening up is cutting the cost of everything and using small, capable electronics to fly thousands of our payloads for the cost of one big payload."
Each Project Aether payload cost between $500 and $1,000, and the balloons cost about $200 each.
Seeing Auroras Higher and Brighter
For Project Aether, a payload "is literally a lunchbox cooler that has housing insulation foam on the inside and a space cut out for GPS tracking and experiments," Longmier said. Payloads weighed 4 pounds (1.8 kilograms), on average.
The experiments flown on board the balloons were designed by Texas A&M undergraduates and high school students from around the country.
The projects included a substance called aerogel, used to capture micrometeorites, and a bacteria culture that will be compared to control samples on the ground, to study the effects of solar radiation on living organisms.
The cameras, meanwhile, were commercially available GoPro models that the team modified to take long-exposure shots and to capture aspects of auroras normally invisible to the naked eye.
"We wanted the cameras to be much more sensitive to the auroras, so we've been taking out filters that are normally in the lens assembly so that the [camera's light] sensor can detect the full spectrum, from ultraviolet to visible to near-infrared light," Longmier explained.
The photographs and video were then converted to false-color images, with ultraviolet portions of the auroras tinted blue and infrared portions mapped to red or pink.
"The aurora appears brighter, and they seem to extend higher and lower," Longmier said of the modified images.
The balloons used in the project were about 8 feet (2.4 meters) wide when inflated on the ground, and they took roughly two hours to reach an altitude of about 100,000 feet (30 kilometers).
At that height, the change in air pressure caused each balloon to expand to almost 30 feet (9 meters)—"about the size of a small house"—before popping, Longmier said.
Once the balloons burst, the payloads fell back to Earth on parachutes, and scientists found them using satellite and ground-radio GPS.
Not everything could be done with commonplace resources, however: Often the payloads fell in out-of-the-way regions of tundra reachable only by dogsleds, cross-country skis, or helicopters.
Aurora Project Sequel Coming Soon?
Project Aether's balloons also flew a prototype plasma sensor that Longmier hopes to use in his planned fleet of aurora probes.
Such spacecraft flying through auroras and collecting real-time plasma measurements could help scientists unravel the coupling of energy between Earth and the sun in the upper atmosphere—a process that creates solar storms, which can affect satellites and electronics.
The plasma sensors didn't actually take any readings during Project Aether because the balloons were flying too low—auroras typically occur at altitudes of about 60 miles (90 kilometers) and higher.
However, Longmier said, the project did measure "the conductivity of the upper atmosphere at 30 kilometers [18 miles]. This conductivity can be significantly enhanced and affected by x-rays emitted from the aurora overhead."
Marc Lessard is a space physicist at the University of New Hampshire whose team recently launched a 40-foot (12-meter) rocket 189 miles (300 kilometers) above Earth to study auroras.
A fleet of spacecraft capable of measuring auroras globally with high resolution "would definitely be useful" in helping to understand the variety of auroras and the complex sun-Earth interactions that give rise to them, Lessard said.
"The sun puts out sunlight, which takes eight [minutes] to reach us and gives us warming. But we also get a lot of energy through the solar wind, which typically takes two to three days to get here," said Lessard, who was not involved in the balloon project.
"How that energy gets deposited is extremely complicated, because the Earth's magnetic field acts as a shield. But we do get that energy ... and it turns out that the last part of that energy-transfer process involves the formation of auroras."
Lessard noted, however, that synchronizing thousands of spacecraft flying at high speeds could prove challenging.
"They'll need to be moving fairly fast, about seven or eight kilometers [four or five miles] per second," he said. "It would be a very expensive mission just trying to get everything coordinated."
Still, Project Aether is already planning a sequel, team leader Longmier said: "We're joking with GoPro that this is only Alaska: Part One."