Did an F-22 shoot down an Illinois hobby group's small radio balloon?

Did a superpower showdown provoke the U.S. into using a fighter jet to shoot down a hobbyist group's research balloon in Canada? That's the question the public — and the FBI — wants to answer, after the U.S. military shot down several unidentified airborne objects last weekend.

A military spokesperson tells NPR it's their understanding that the FBI has spoken to the hobbyist group in question — the Northern Illinois Bottlecap Balloon Brigade, based just north of Chicago — in an apparent attempt to determine whether their small balloon might have inadvertently caused a big ruckus.

Updated February 18, 2023 at 1:20 PM ET

But the hobbyist club's members are warning that while their balloon, whose radio callsign is K9YO-15, is missing in action, it's too soon to say whether it was shot down by a warplane. They also say their balloon launches follow all federal regulations.

The Biden administration said on Friday that it cannot confirm any reports potentially identifying the objects that were shot down, citing ongoing investigations.

Questions rise about an object shot down over the Yukon

The as-yet-unexplained incident began on Feb. 10, when U.S. defense officials detected a "high-altitude airborne object" over U.S. airspace in Alaska, days after a Chinese balloon crossed much of the continental U.S.

Two F-22 fighters were dispatched to track the mysterious object over Alaska. When it crossed the international border into Canada, aircraft from the Royal Canadian Air Force joined the formation. It quickly prompted calls between President Biden and Canada's Prime Minister Justin Trudeau, and between Defense Secretary Lloyd Austin and Canadian Defense Minister Anita Anand.

With the use of force authorized, a U.S. F-22 used an AIM-9X Sidewinder missile to shoot down the cylindrical object over Canada's Yukon Territory on Feb. 11.

Officials have not yet offered an explanation about the origin or purpose of the unidentified object. But an intriguing theory quickly emerged in the community of hobbyist balloon enthusiasts: that a high-altitude "pico" balloon, similar to a Mylar party balloon, was shot out of the sky.

And as it happens, Saturday, Feb. 11, was the last time the amateur group in Illinois heard from their balloon.

"98% certainty" that it's the same balloon, an expert says

"Before the Yukon balloon was shot down, us amateurs were watching [K9YO-15] go towards Alaska," Dan Bowen, a stratospheric balloon consultant, told NPR.

Bowen, who 12 years ago helped to research and design small balloons like the one used by the Illinois club, says he and others were using a tracking website to follow K9YO-15. The tool also gives a forecast of a wandering balloon's likely path.

When the prediction showed K9YO-15 heading from Alaska over the Yukon, Bowen said, "we really hoped it wouldn't be intercepted. But we knew the moment that the intercept was reported, whose it was and which one it was."

Asked if he believes the Northern Illinois Bottlecap Balloon Brigade's balloon was shot down, Bowen didn't hesitate.

"Yes. Absolutely," he said. "You know, I would say with 98% certainty."

A spokesperson for NORAD, the joint U.S.-Canadian military organization, told NPR on Friday that from their understanding, the FBI has spoken with the balloon hobby club.

Representatives from the FBI and NORAD told NPR on Friday that they have no new information to provide, with the FBI saying that "the overall recovery operation is ongoing." But Canadian officials said Friday that they called off the operation after they searched the "highest probability area" without success. "Given the snowfall that has occurred, the decreasing probability the object will be found and the current belief the object is not tied to a scenario that justifies extraordinary search efforts," the Royal Canadian Mounted Police said it was terminating the search.

The balloon had already circled the Earth 6 times

K9YO-15 was launched last fall by members of the Bottlecap Balloon club — the group takes its name from the Pixar movie Up, which prominently features both balloons and a bottle cap.

Its journey began with a launch from Libertyville, Ill., on Oct. 10, 2022. Before it disappeared, it was one of the club's longest-flying balloons; in its 123 days aloft, it had circumnavigated the Earth nearly seven times.

On Tuesday, the club published the balloon's last known coordinates and its projected path. "For now we are calling Pico Balloon K9YO Missing in Action," wrote club organizer Cary Willis.

In the days since, speculation has grown over the possibility that the U.S. Air Force shot down the 32-inch silver Mylar balloon. On Friday, the NIBBB posted a statement saying there is presently no connection between its balloon and the unidentified object shot down by the F-22 last weekend.

"As has been widely reported, no part of the object shot down by the US Air Force jet over the Yukon territory has been recovered," the club wrote. "Until that happens and that object is confirmed to be an identifiable pico balloon, any assertions or claims that our balloon was involved in that incident are not supported by facts."

A representative for the club did not respond to an interview request.

You wouldn't need a missile to take the ballon down

Balloons like K9YO-15 are inexpensive — when asked for a cost estimate, Bowen replied, "I don't think you'd break $100."

"Some of them are the same silver balloons you buy in the grocery store," he said, "and I mean from the same manufacturer of the same model."

After they're launched, the balloons expand as they climb, swelling until the Mylar envelope pressurizes. They stop rising at altitudes where the air density is equal to the balloon's density. The pico balloons "just float the same way a fish bladder or a submarine does underneath the water," Bowen said.

One thing that might make a pico balloon hard to shoot down, Bowen said, is its small size. "The entire thing that the balloon lifts is a business card-sized circuit board and two little tissue paper-thin solar cells," he said.

Those characteristics help the balloons meet legal regulations that require them not to pose a danger to aircraft. They're made to be safe — and a missile isn't needed to pop them.

"These balloons are pressurized just below the point of popping," Bowen said. "So if you can hit them with [aircraft] turbulence, they'll pop. If they get hit with a sonic boom from nearby, absolutely going to pop. Those are the easiest ways to pop them."

The Bottlecap club says its balloons sometimes go silent

In its Friday statement, the club also noted that it's normal for pico balloons to lose touch. "It is not unusual for significant periods of time to elapse between received transmissions," they explained, adding that K9YO-15 had previously gone MIA around Christmas before reappearing in late January.

One explanation is that the balloon's GPS pings require solar power. At higher latitudes in wintertime — like the recent path of K9YO-15 — the tiny solar panels can struggle to receive enough sunlight to power the balloon's lightweight systems.

The balloon was equipped with a GPS module, a transmitter, a tiny computer and a small solar panel package. Its total payload weight was just 16.4 grams, or about half an ounce, according to a blog post about the launch.

Federal law requires most large flying objects to be registered with the Federal Aviation Administration. But amateur pico balloons, like K9YO-15, are so small and light that they are not subject to those requirements. (Its radio transmitter is registered with the FCC.)

Amateurs await potential policy changes

Balloon enthusiasts say they're happy to see so much interest in their hobby. And they're hoping to be able to keep pursuing it, even if the U.S. and other countries adopt new rules.

"These are often launched by schoolchildren," Bowen said. "The amateurs who have figured this out have gone to schools to get them excited about science and engineering, and the kids just love the ability to see their little robot creature wandering the planet."

The students track their balloons, much like the Bottlecap Brigade club. As the U.S. and other countries take a fresh look at balloons and high-altitude objects, Bowen notes that there are 10 to 20 more balloons still out there, making their way around the world — "and there's no way for us to bring them down remotely." [Copyright 2023 NPR]