The US Air Force may have shot down an Amateur Radio Pico Balloon over Canada

Since the famous takedown of a suspected Chinese spy balloon, US jets have shot down a total of three more unidentified balloon objects, now suspected by officials to be 'commercial or benign'. There is speculation that at least one these three objects may have been an amateur radio 'pico' balloon.

One part of the amateur radio hobby is launching high altitude balloons with various radio and other payloads. Larger amateur radio balloons launched in the USA require FAA clearance, need a radar reflector attached, and usually continually transmit APRS telemetry before naturally popping and falling back to earth after a few hours, just like a weather balloon.

However there is also the simpler 'pico' ballooning hobby, which involves the use of mylar helium party balloons to launch small solar powered payloads that are only a few grams in weight. They typically transmit low power WSPR at HF frequencies and can only transmit whenever there is sufficient solar power available. Amateur radio or SDR hobbyist stations around the world can pick up these transmissions, and report them on and/or Well built balloons can totally circumnavigate the globe several times over several months before degrading.

While termed 'pico', the party balloons used can still be roughly a meter in diameter on the ground, with some latex balloons potentially expanding further at high altitudes due to the low atmospheric pressure. These balloons can be legally launched from almost anywhere in the world. In particular in the USA there is no FAA clearance required to launch them due to their payload being much less than the limit of 4 lbs (1.8kg). 

32" Silver Orb Shaped Mylar Balloon used for Pico Ballooning
32" Silver Orb Shaped Mylar Balloon used for Pico Ballooning

There is speculation that at least one of the objects shot down over Canada, Yukon by a US Air Force jet may have been amateur radio pico balloon K9YO-15 which was launched from Illinois on October 10 2022. It was on it's seventh circumnavigation of the globe after being aloft for 123 days.

The launch blog post indicates that the K9YO-15 balloon was flying a silver mylar 32" sphere SAG balloon which appears to be this one from Unlike latex or rubber weather balloons which inflate and stretch as they rise into lower atmospheric pressures, these mylar balloons can't stretch, so their fully inflated ground size will be the same as their size at high altitudes, meaning the pico balloon won't get much bigger than 32". The payload was a GPS module, Arduino, SI5351 used as a WSPR and APRS transmitter and a solar panel, all together weighing 16.4 grams. A pentagon memo notes that the object shot down over Canada was a "small metallic balloon with a tethered payload" which fits the description of the pico balloon exactly.

The K9YO Pico Balloon Payload
The K9YO-15 Pico Balloon Payload
An (unrelated) Example Amateur Radio Pico Balloon Launched by a Naval Academy
An (unrelated to this story) example Amateur Radio Pico Balloon launched by a Naval Academy (Source:

The K9YO-15 balloon ceased all WSPR telemetry transmissions while flying just below Alaska since Feb 11 00:18 UTC (just before sunset in Alaska when the solar panels would stop working).

By using NOAA wind models and the last known location by Alaska, K9YO-15 was projected to have been over Yukon when the US Air Force shot down the unknown balloon object at Feb 11 20:41 UTC (3:41 PM EST / 1:41 PM Yukon time according to Canadian Defense Minister Anand). Reports put the altitude of the shot down object at approximately 40,000ft (~12000 meters), which matches the projected ~11500 meters of K9YO-15. Based on the previous days transmission times, it is suspected that if it were operational, the balloon would have begun transmitting again sometime later in the Yukon afternoon when the sun was stronger, but no transmissions have been seen.

On February 14th the balloon was declared as missing in action by the launch group. 

K9YO projected location at the time the object was shot down.
K9YO projected location at the time the object was shot down.

The search area for the fallen balloon debris is reported to be in difficult to access terrain between Dawson City and Mayo. If we do a rough overlay of the predicted trajectory over a Google map, we can see that the predicted location of KY9O-15 at the reported time of the missile impact matches this description very well.

Rough trajectory overlay
Rough trajectory overlay

Over on Twitter @ikluft (KO6YQ) has been reporting on this speculation, and has been keeping an eye on K9YO-15, awaiting telemetry transmission. We recommend following his account for further updates.

Twitter user and ex project Google Loon engineer @BalloonSciDan has also speculated that the objects shot down may have been pico balloons.

Over on Reddit @ikluft (KO6YQ) has also written some insightful information:

I see you're all talking about my tweet. Yes, we are still watching to see if K9YO-15 transmits any telemetry today.

So far K9YO-15 has not sent any new telemetry since Friday before sunset over Alaska. Some have misread confusing data presentation on Sondehub which lists last known telemetry as covering a time range from then to now. Currently the last we've heard from K9YO-15 was Friday Feb 10 before sunset over Alaska (00:48 GMT Feb 11). But the map on Sondehub does show the last reported position.

These floater balloons often use only solar panels, no batteries. Batteries were dropped from the projects early on because they have limited charging cycles before they stop accepting a charge, especially in the harsh temps at altitude, -40F/-40C or worse. When the battery stops accepting a charge, it ends telemetry from the mission. So they only report telemetry during daylight, when the sun is at a high enough angle to illuminate the tiny solar panels. In the Arctic winter, the days are short and the sun might not get high enough to wake up the electronics. So it stays dormant for one or more days until it drifts back down to lower latitudes where there's more sunlight. So K9YO-15 was in a period where watchers didn't expect to hear from it for a few days. But we expected it today. So far nothing. As I write this, daylight is almost done way up there for Tuesday, Feb 14.

We (the Amateur Radio balloon community) only expect any telemetry from it today would be via WSPR, none via APRS. WSPR uses HF and can be received at long distances, where it's relayed to Internet map sites. APRS is (usually) on VHF and UHF, only received by line of sight. There are no relay stations in range of today's projected flight course in northern Ontario and James Bay, Canada. So APRS-fed sites wouldn't show updates today anyway.

The club in Illinois that built the balloon has tracking links at - you'll have to scroll down to find K9YO-15.

For an introduction, I'm Ian KO6YQ. I was involved in the first Ham Radio balloons that circumnavigated the globe starting in 2016, launched from San Jose, California. I had roles on them including tracking analyst and social media spokesman. I also organized and led the Ham Radio tracking teams which recovered the Civilian Space eXploration Team (CSXT) first amateur rocket to (suborbital) space in 2004.

Explaining a discrepancy with time reporting on Sondehub, KO6YQ notes:

Time has run out for solar power to provide any telemetry on Wednesday, February 15. So far, no new data. For those who were confused by it, remember that Sondehub has problematic data presentation so don't use it for anything other than mapping the last known position. A reliable place to check for K9YO on WSPR is the WSPR Spots:

Frequently asked Questions (FAQ):

Since this story has gone viral and now entered the mainstream media, we thought we'd answer a few common questions that we're seeing in the media and comments.

Who is launching pico balloons and why?

Pico balloons are typically launched by ham/amateur radio hobbyists, universities, researchers, schools or kids STEM programs. The idea of launching a low cost balloon that can be tracked while travelling the world is a fun project for hobbyists and a great STEM learning experience for kids.

You can track other currently active pico and larger amateur radio balloons at

You might also be interested in tracking regular weather balloons which are launched by meteorological agencies around the world usually twice per day. These are designed to only last a few hours in the air before popping. They can be tracked at A popular hobby of radio enthusiasts is chasing these weather balloons and being the first to recover the fallen sensor package called a radiosonde.

A pico balloon is essentially a kids party balloon. Why aren't there thousands of kids party balloons circumnavigating the globe? 

Balloons will inflate more as they rise into the atmosphere, since higher altitudes have lower pressure. A kids party balloon would typically be inflated fully on the ground. If a careless child released a balloon it would rise up, and pop within a few hours, as it reaches an altitude of around 5000ft - 30,000ft (1500m - 9000m) or higher where the internal pressure of the balloon is too great for the balloon's material to hold it.

Pico balloons are weighted by their payloads, and are only partially inflated on the ground. The goal is to inflate with enough Helium or Hydrogen to get the payload to rise at ground level, but allow enough internal space for the balloon to expand without popping as it rises. The weighted balloon will eventually reach an equilibrium point at some altitude where it's fully inflated, but can't rise any higher due to the weighting. This is called being 'neutrally buoyant'. The balloon launcher can use a calculator (such as this one) to determine the right amount of helium to use based on the balloon size and payload weight.

Mylar balloons are used because helium atoms will leak out of the walls of latex/rubber balloons, and they will be flat within a few days. With Mylar balloons the leakage is much slower and they can stay inflated for months.

How can a pico balloon circumnavigate the globe?

As mentioned in the previous question, it's possible to engineer the height that the balloon will fly at by only partially inflating the balloon on the ground. Once at the desired altitude, winds will eventually pull the balloon into global jet streams that take the balloon all around the earth at an average speed of 80 - 140 mph (129 - 225 km/h).

A website like Ventusky can be used to view the current jet streams at 40,000ft (12,000m), the altitude that KY9O-15 was neutrally buoyant at. 

Are pico balloons legal?

In the USA the regulations defined in PART 101 - MOORED BALLOONS, KITES, AMATEUR ROCKETS, AND UNMANNED FREE BALLOONS are only applicable to larger balloons. Small balloon payloads are exempt from these regulations. Similar exemptions exist in most countries.

In California helium balloons in general have been banned, to stop pollution, damage to wildlife, and to protect power lines. 

The transmission of the WSPR and APRS telemetry radio signals would be allowed under amateur radio rules. UK, Yemen and North Korea are countries that prohibit transmissions from balloons, and compliance can be achieved via geofencing the transmissions in the software.

All information suggests that the NIBBB hobby club and KY9O's balloon were operating perfectly legally. 

What exactly was the payload on the KY9O-15 pico balloon?

The payload was a GPS receiver, an Arduino microcontroller, a radio transmitter and some solar panels. The solar panels power the electronics when in sun, and the GPS receiver determines the global coordinates of the balloon. The microcontroller is the 'brain' of the payload which reads the GPS coordinates from the GPS receiver, and tells the transmitter to send out a WSPR radio signal advertising the balloons ID and coordinates.

These are all common off the shelf, small components that could all fit in the palm of a hand. They would in total cost under $100. K9YO's payload in total only weighed 16.4g (0.58 oz). 

An F22 with all it's radio sensors should have picked up the transmissions from the pico balloon. Why didn't it?

Pico balloons usually don't carry batteries because they are heavy and degrade over time. So instead they carry paper thin solar panels. So the balloon circuits and transmitter are only active when in strong sunlight, any other time it is completely quiet and powered down. It's possible that in the weak Yukon sun at high latitude wouldn't have been strong enough to power the WSPR transmitter until later in the day.

How could a tiny 32" balloon be spotted by radar? How could a sidewinder missile lock onto it?

The pico balloon was made out of metallic mylar material which would easily show up on a modern radar system. It's possible that in the past before the Chinese spy balloon incident, radar operators would ignore or filter out slow moving small objects like insects/birds/balloons that pose no threat.

The sidewinder has a fragmentation warhead, so an explosion near the balloon would easily take it out. The metallic mylar material would easily reflect the sun's infrared, and against the cold background of the sky/space it would be easy for the IR heat seeker sensor on the sidewinder missile to track it. 

The K9YO balloon was flying at altitudes used by commercial airliners. Is there any risk to them?

A jet coming across a pico balloon in the first place would be very unlikely, and even more unlikely for it to make it's way in to an engine even if an aircraft flew directly at it. But there is some risk that a balloon ingested by an jet engine could cause issues. However given their lightweight nature it seems unlikely that there would be any massive damage, if any at all.

What is WSPR and APRS?

WSPR (pronounced as 'whisper') stands for Weak Signal Propagation Reporter. It is a type of radio signal protocol used by amateur radio hobbyists. Because of the way it is designed, it is possible for WSPR to be transmitted with very low power (such as the tiny amount of power possible from small solar panels), and still be received by amateur radio ground stations all over the world. The WSPR signal encodes it's callsign ID, and the transmitters GPS location. Amateur ground stations will upload received WSPR data to sites like

APRS or "Automatic Packet Reporting System" is another protocol used by amateur radio hobbyists. However, these signals don't travel globally, rather they can only be received locally with line of sight. The advantage is that APRS signal can be transmitted much faster (assuming sufficient power).

Are we 100% certain that the object was the K9YO pico balloon?

No, despite the circumstantial evidence, there is still some doubt. The balloon was already old and probably near the end of it's life. The sun in the high Yukon latitudes is also weaker, meaning that the solar panels might not be getting sufficient sun to power the circuits. The balloon had previously gone missing for 30 days before reappearing. And the transmitter was showing signs of drifting in frequency.

Are there any other globe trotting radio projects?

Yes, there are small autonomous boats or 'drift buoys' travelling the seas through natural currents. These also use WSPR and APRS to report their location. hitchBOT was a hitchhiking robot that relied on travelling strangers to find and carry it around the world. It had a GPS receiver and 3G radio.


  1. admin

    Please note this is a technical blog, not a political blog. Please keep comments technical in nature, related to the story and refrain from degenerating into political talk. Purely political comments without any technical content will eventually be removed.

  2. Glenn

    To return to the original topic and to follow up on my suspicion that the balloon *may* still be active but so far off frequency that it is no longer spotted due to a badly drifting frequency reference, here is a plot of the final 25 hours of WSPR spots from KFS at Half Moon Bay in California and operated with high receiver frequency accuracy:
    The green boundaries show the lower and lower WSPR band limits beyond which most WSPR receivers will NOT report a spot. A poorly calibrated station might be in error to report what it believed to be in-band but most calibrated receivers, such as the one at KFS which has extended reporting limits, will NOT report a WSPR transmiission.
    The Frequency trace shows the actual balloon frequency drifting out of normal WSPR band about half way into Feb 11 while the Drift plot shows that the on-board frequency reference in addition to drifting slowly is also drifting rapidly at the very end within the 2 minute WSPR transmission, perhaps due to battery voltage dropping as the craft went out of sunlight..

    I think this adds further credibility to the hypothesis that the balloon may not have been shot down at all but is possibly still active but so far off frequency that the worldwide network of WSPR receivers no longer report it. Perhaps a coordinated effort to tune out of band, perhaps above the 14.0972 MHz limit, would reveal that the balloon is still active.
    I realize that this hypothesis may dampen the rampant speculation about other possibilities but I believe the data is credible enough to be worth pursuing.
    Other well-calibrated WSPR spotters agree with KFS regarding the balloons last reported transmissions.
    Glenn n6gn
    Fort Collins, CO

  3. John Doe

    I’ve launched Radiosonde weather balloons personally for the government. A rubberized balloon about 10ft in diameter that carries a small circuit card inside a styrofoam box. No FAA checks needed.

    IMO, this balloon scare is an attempt to create mod style chaos to take the country to war.

  4. MaxAF

    I’m more inclined to believe the pilots descriptions of these objects rather than this duplicitous administrations claims that they were just party balloons, nothing to be concerned about. I’ll believe a highly training fighter pilot over a guy that doesn’t know where he is most of the time.

      • Dog Food

        I’m pity you. America’s create havock, Europe suffer till now and dunno when will restore their economy while America’s benefits all. Europe such a Yes Man. Pity NATO. Being betrayed from America’s still act nothing happened. While Europe people suffering, those govern full of pocket. LOL. Good NATO Dogs 🤣🤣😂😂

        • AbbeysLactose

          Explain how America giving countless billions in “aid” to NATO countries is “create havock”. How about all NATO countries are evil and all will suffer sooner than later at the expense of a small group of people who run the world. Ukraine is a joke and I hope Putin steamrolls the entire country just as an “F U” to NATO.

          • Dog Food

            Wait and see. Another 911 quadruple massive attack coming soon. Got to hide before you going to die sooner or later. Naive and dumb kids.

            • PutinIsDictator

              Not educated, insult … this is always argument from troll.

              NATO ? Have you ever looked a MAP ? Of course not … Putin / Russia second army of world … screwed since 1 year in Ukraina … here is the truth … 36 himars put the mess in this bunch of drunk / looter soldiers …

              USA is so bad … yes … like EU … like UK … but all rich russians want to put their child in high school , buy house there … to spend time … who is US / EU / UK dream to buy house in shit russian land ? Non one … to make what ? Meet vatniks drunks … lol ??

              Keep your args … in EU all houses have WC inside … not like in 100 Km of Moscow … where WC are still in garden … villages where time has been frozen and people like there like in ’50 !

  5. Dog Food

    Elections are coming around. That’s why Biden show off to win population of American. Kick him out and don’t elect Thumpet too. These morons dunno how to make a good government. They just only know how to provoke wars. Obama is the last best President.

    • radiofreeeurope

      Yes, Obama was best. Assassinated his own citizens with drone strikes, Joked the drones are “really good at killing people” , dropped bombs on Iraq, Syria, Yemen, Pakistan, Afghanistan, Libya and Somalia, sold $100 BILLION in arms to Saudis, are you talking about THIS Obama? Obama got a “Peace” Prize for bombing women and children in the middle east.

      • AbbeysLactose

        Hey man, Obama wanted to hold the record for most civilians killed with a drone strike by a nobel peace price winner, and he got that record! Don’t deny the career politician his evil dreams!!!

    • AbbeysLactose

      Biden is such a screwup that the only thing he will be remembered for is sniffing kids and his son smoking crack.
      Funny that compliant little Europoors think their opinion is relevant in US politics at all.

  6. Bill

    Wow–I wondered at the veracity of the early statements from the government. What a lot of purposely misleading nonsense they put out: “roughly the size of a small car” or something like that.
    I wondered too if it might be a small amateur balloon. Sure enough! I’ve always wanted to get involved. Years ago I was introduced to the wonders of weather balloon chasing by W8DMR.
    Troubling news tonight on NPR: Biden apparently wants to restrict balloons now. Get ready to write when the Federal Register publishes an NPRM.

    • Anon

      They didn’t go up with a tape measure, they’re guessing the size from the radar return and range information, and maybe the pilot got a glimpse. It’s closer to the size of a small car than a 747.

  7. Glenn

    I notice that the last WSPR spots from well calibrated stations, KA7OEI-1 and KFS, spotters with 1 Hz or better frequency control show the transmit frequency to be 17 or 18 Hz ABOVE the top of the WSPR band. The reported frequency prior to that, shows this drift has been ongoing. In general that balloon transmitter has had very poor frequency control since a day earlier spots were much lower . Once it drifts above the upper limit of even uncalibrated spotters who would still hear it, there would no longer be ANY WSPR reports even if it came back on in the next sunshine.
    It may still be copiable if there are listeners tuned above the 20m WSPR band.
    Glenn n6gn

  8. Brad Sage K6JPR

    OMG! California passed a law (Assembly Bill 847) last September banning mylar/electrically conducting balloons. These to be phased out over four years giving time for the development of non-conducting versions. Fine=$2500.00 per occurrence. Reason given….several hundred powerline shorts/outages per year by balloon contact, some fires resulting…also wildlife eating downed balloons. Nothing in the law addresses the state’s concerns about costs of the USAF shooting missiles at the illegal balloons! The balloon hams must now purchase, and launch, their picos out of California! We are sooo safe here in the Golden State!

  9. Jeb Dog Millionaire

    The IR seeker of an AIM-9X is sensitive enough to acquire and track the heat signature of a 36″ balloon with a total weight of less than 17 grams outputting less heat than a toaster? Russian and Chinese 5th gen fighters are in trouble.

  10. Bill Brown

    I’ve been flying dozens of these circumnavigating Pico balloons since 2016 and have never had any issues. I put a geofence in my Skytracker code to prohibit transmitting over regions of the World that don’t allow that. Yemen, North Korea and believe it or not…The United Kingdom. They don’t allow ham radio to be used on anything that flies…aircraft, hot-air balloons or Pico balloons. – Bill WB8ELK

  11. Bill Brown

    I would think their search of the remote Yukon wilderness would be fruitless since striking a Pico balloon and payload would likely instantly vaporize it….nothing would be left. – Bill WB8ELK

    • Amy

      I think they detonate the missile *near* near the balloon so the shock blows it up. There’s probably some debris, but it would take forever to find.

  12. Bill Brown

    Taking out a Pico party balloon with a Sidewinder missile is akin to swatting a mosquito with a sledgehammer. Hopefully they will dial down their RADAR to not see and scramble jets to go after any party balloon that they see. There are many sources of these balloons, release from birthday parties, wedding or some other event so if they keep scrambling jets after all of these they will be very busy and spending millions in missile launches.I also did a HYSPLIT analysis very similar to what is shown in this article and it does indeed closely matches the location where a metallized balloon was shot down. The NIBBB group used a silver foil ORBS balloon. The scrambling of jets in Romania was also likely a Pico balloon that fortunately survived their chase. The image you show of the Naval Academy payloads is one of my 20m WSPR Skytrackers that weighs around 12 grams so way way under the Aviation regulations and requirements.. – Bill Brown WB8ELK

      • Michael Wallace

        One news report describing an intercept (unknown which one) it was stated that the first ‘shot’ had missed. These kinds of low speed runs with guns or otherwise are not in the normal mission profile for those weapon systems and likely pretty risky to pilot and aircraft. I would expect some very high level US and ITU discussions are taking place. Expect a quick clamp down on any / all activity around theses types of balloons which is a shame.

  13. Anonymous

    What stencil is the crew chief going to use for Capt. Courageous’ F-22? A party balloon? A nerd with a black eye?

  14. Curt Faulk

    @Michael Simmons…

    Big sky, little airplane. That operating theory worked very well for me over a 37-year career as an air traffic controller.

    So, no, these things aren’t a threat to aircraft. Hence, no legal requirement to receive approval from the FAA to launch them.

    Much more of a threat to aircraft are illumination of cockpits by handheld lasers and the odd rogue drone operating near an airport. Now those are things to actually worry about, if you’re dead-set on worrying about something. (I’m not.)

    • Ted Lyon

      Pico Balloons fall under FAA 101 exemption:

      Regulations don’t apply if your payload meets these conditions:
      • Your payload is less than four pounds
      • Or, your payload is less than six pounds and the smallest surface is more than 36 square inches (6 inches by 6 inches)
      • If you have two payloads, they weigh less than 12 pounds together
      • If you have a rope, it takes less than 50 pounds of force to break it off (just don’t use carbon fiber, regular rope should be fine).
      If you meet these conditions, then You’re FAA 101 exempt. Almost all amateur balloon payloads are exempt and not subject to the requirements of the regulations.

      Not only that CFR 91.113 about aircraft right of way states:

      (1) A balloon has the right-of-way over any other category of aircraft;

      (2) A glider has the right-of-way over an airship, powered parachute, weight-shift-control aircraft, airplane, or rotorcraft.

      (3) An airship has the right-of-way over a powered parachute, weight-shift-control aircraft, airplane, or rotorcraft.

      However, an aircraft towing or refueling other aircraft has the right-of-way over all other engine-driven aircraft.

    • Anonymous

      An encounter between balloon and an aircraft in cruise is HIGHLY unlikely. An ingestion is EXTREMELY unlikely — on the order of a needle through another needle on a dart board. There’s a lot of airplane pushing around a lot of air that isn’t engine.
      But in the event it does happen? Not much: it gets mulched. A compressor miiight burp and puff. But unlikely.
      Fiberglass is similar density to bone. And a turbofan can swallow small birds without noticing much.
      A series of them might cause a stall? Maybe? Ingesting flocks of birds have been known to. And you wouldn’t want to roll the dice on approach or takeoff.

    • Chris

      It looks like a “Happy Birthday” helium balloon. I am pretty sure this is not what was shot down; a good gust of wind would take this tiny little thing out. This article is laughable.

      • steverinnm

        Yet, “this tiny little thing” was launched over 4 months ago and completing it’s 7th trip around the earth, a 4-month, 24/7, 165,000 mile flight thru numerous storms at continuous sub-zero temperatures, reliably transmitting GPS coordinates of it’s journey and furnishing NOAA with valuable air current data. Yep, “a good gust of wind would take this tiny thing out”…SMH.

Post a comment

You may use the following HTML:
<a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <s> <strike> <strong>