Did the government use a Sidewinder to take out a small hobby balloon?

In his first public comments since U.S. aircraft shot down multiple unidentified objects over North American airspace, President Biden didn’t offer many specifics.

“Our intelligence community is still assessing all three incidents,” Biden said of the shoot-downs on Feb. 10, 11 and 12. “The intelligence community’s current assessment,” he added, “is that these three objects were most likely balloons tied to private companies, recreation or research institutions studying weather or conducting other scientific research.”

In other words, the objects were probably innocuous, as The Washington Post reported before Biden’s comments. In fact, reporting on Thursday offers an intriguing possibility for the object downed on Feb. 11 over Canada’s Yukon Territory: it may have been a three-foot balloon launched in October by hobbyists from Illinois.

To be very clear, the hobbyists themselves are not affirmatively claiming that this is the case. (The Washington Post reached out to the head of the organization by phone and email. We have not yet heard back.) But in a blog post at the website of the Northern Illinois Bottlecap Balloon Brigade (NIBBB) - yes, the whimsical name is a reference to the movie “Up” - the group has labeled its small balloon as “missing in action” as of Tuesday.

“Pico Balloon K9YO last reported on February 11th at 00:48 zulu near Hagemeister Island after 123 days and 18 hours of flight,” it reads, identifying a small island a bit northwest of where the peninsula that leads to the Aleutian Islands connects to mainland Alaska. The post goes on to note its reported height and expected trajectory - a bit over 39,000 feet and headed into Yukon Territory.

[Unidentified high-altitude objects put Alaskans on alert]

The unidentified object shot down in that region was felled from “approximately 40,000 feet” on Feb. 11 at 3:41 p.m. Eastern, according to a news conference held by Canadian authorities.

But let’s back up. There’s a lot of useful information in that original quoted sentence that provides insight both into this specific device and, more broadly, amateur balloon enthusiasts who contribute various flying objects to the skies over North America and the world.

When news reports of the suspected Chinese spy balloon first emerged earlier this month, we noted that sending balloons high into the atmosphere was a common activity for hobbyists and even school classrooms. The materials are cheap and the process simple. You, too, can take photographs of the curvature of the Earth for $300 of supplies from Amazon.

But those flights are short-lived, in part because they tend to burst at high altitudes. In recent years, there’s been a movement toward launching smaller, more robust balloons that can carry transmitting devices adapted to be particularly small. These are pico balloons, mylar balloons that can be little larger than a balloon for a children’s party. Inflate with helium, attach a transmitter and the balloon can stay aloft for months or years, buffeted by the wind.

The hobbyist site RTL-SDR.com notes that pico balloon K9YO - the one launched by NIBBB in October - was probably this 32-inch mylar balloon. If it was the one downed by a U.S. fighter, it was struck by an AIM-9X Sidewinder missile, a projectile that itself has a 5-inch diameter.

[Objects shot down after suspected Chinese spy balloon were likely for ‘benign’ research purposes, Biden says]

NIBBB reports that K9YO had recently begun its sixth trip around the globe when it went missing late in the evening on Feb. 10. (“00:48 zulu” is just after midnight Greenwich Mean Time.) Communications outages are not uncommon with such devices, given that they rely on solar power to communicate. In fact, K9YO had gone radio silent for about four days in late January. (There are also nations that ban transmission in their airspace, including the United Kingdom and North Korea, so the devices are programmed not to transmit within certain latitude-longitude regions.)

Ian Kluft, a hobbyist who was one of the first to speculate that K9YO might have been the Yukon object, noted on Twitter that the Arctic was particularly tricky for receiving information from these devices. It’s February, after all, and hours of sunlight and low sun angles make generating solar power more difficult. There are public databases for tracking pico and other balloons, like Sondehub. (A radiosonde is a small transmitting device used for decades on government weather balloons.) It’s possible that K9YO might begin transmitting again, updating its location and solving the mystery. Or maybe it’s in tiny pieces on the Yukon ice, blown to smithereens by a highly advanced missile. Kluft is still watching.

Aviation Week’s Steve Trimble reached out to federal officials before Biden’s speech on Thursday to see if they thought the government had successfully neutralized NIBBB’s radio-equipped party balloon.

He received a lot of “no comments.”