Pico Balloon
On April 13, 2025, at 8:15 AM local time, the second Rio ARC Pico Balloon, sponsored by Tom (WT5TX), was launched southwest of Harlingen, TX, aiming to circumnavigate the globe and float for weeks. Track its journey here: watch here.
What is a Pico Balloon?
A pico balloon for ham radio is like a tiny, adventurous party balloon that decided to ditch the birthday bash for a wild ride in the stratosphere. Picture a shiny, helium-filled Mylar bag, no bigger than your average beach ball, stuffed with a whisper-light radio transmitter that's basically a hamster on a tech wheel, frantically beaming digital signals to ham radio nerds below. It’s got solar panels thinner than your patience during a Zoom call, sipping sunlight to keep it alive as long as there is sun on it. This plucky little floater bobs along at 30,000 to 40,000 feet, hitchhiking on jet streams, circling the globe while dodging storms and curious seagulls. It’s the ultimate "I’m outta here" move—part science experiment, part rebellious teen, broadcasting its location like a cosmic postcard until it pops or just ghosts the atmosphere.
Ok, the funny stuff is over, this is what it really is: A pico balloon ham radio is a small, lightweight balloon, often made of Mylar, that carries a tiny amateur radio transmitter as its payload. These balloons, typically 1-3 feet in diameter, are filled with hydrogen or helium to float at high altitudes, around 20,000 to 60,000 feet, in the stratosphere. The radio transmitter, weighing as little as 10-30 grams, is solar-powered and uses protocols like APRS (Automatic Packet Reporting System) or WSPR (Weak Signal Propagation Reporter) to send data such as position, altitude, and sometimes sensor readings (e.g., temperature or humidity) back to ground stations.
Ham radio operators launch pico balloons to experiment with long-distance communication, track global flight paths, and study atmospheric conditions. Due to their light weight and precise gas fill, these balloons can drift for days, months, or even years, sometimes circumnavigating the globe multiple times. The hobby combines physics, meteorology, and radio technology, and is popular among amateur radio enthusiasts for its low cost and scientific potential.
Pico Balloon Serial #2 Daily Blog
Day 5
11:30 AM, April 17, 2025
Balloon Serial #2 stopped transmitting at 11:00 local time today. At the moment of its last signal, it was positioned about 50 to 60 miles north of the Canary Islands, still cruising at high altitude.
The final Sol angle recorded was 45 degrees. During this flight segment, the balloon experienced an average temperature of 35°F, with a high of 55°F and a low of 18°F. Despite the wide range, it seemed to perform well in the conditions.
While active today, it traveled an impressive 372 miles, averaging about 65 mph. Its final reported altitude was over 36,100 feet — still well within the upper atmosphere and moving strong.
Based on its last known heading, it appears to be on a trajectory that could carry it across the northwestern edge of Africa and potentially into the Mediterranean region.
Stay tuned, updates coming early in the morning.
5:45 AM, April 17, 2025
The balloon surprised me this morning by reporting in earlier than expected, with its first transmission coming through at 5:20 AM. It appears to have shifted its course slightly to the northeast, which means it’s less likely to make landfall today before it powers down again.
If it stays on this new path, it should pass over the Canary Islands off the northwest coast of Africa. The onboard temperature is holding steady at a cool 45°F, and once again, it came online right around a solar angle of 45 degrees — consistent with previous mornings.
Overnight, it maintained an average speed of 57 mph. If that trend continues and the heading remains stable, it should cross into Moroccan airspace shortly after it goes offline, probably around 10:00 AM local time.
More updates to follow as the journey continues.
Day 4
1:15 PM, April 16, 2025
Well, well, well... Serial #2 has decided it’s nap time again. Last peep we heard from our high-flying friend was at 12:30 local time, and then—poof—radio silence. Apparently, balloons need their beauty rest, too.
Before drifting off, Serial #2 managed to log a respectable 396 miles under its belt, cruising along at a snappy 70 mph average. Not too shabby for a bag of helium with ambition.
Temperature-wise, it’s been chilling—literally. Our brave floater has been battling the elements, with temps ranging from the high teens to the low forties Fahrenheit. Somewhere between “why did I forget my coat” and “my coffee is now a popsicle.”
The final signal came in with a solar angle of 44 degrees, which sounds fancy and dramatic, like it was doing a dramatic exit stage left. It's still hovering around 35,500 feet, probably enjoying the view and avoiding airline snacks.
If it keeps its current heading, it’s set to tiptoe into Africa sometime tomorrow before its transmitter potentially calls it quits. And here’s the exciting part—if it survives the next night, it’ll officially outlast the much-mourned Balloon Serial #1.
Fingers crossed, helium willing.
7:15 AM, April 16, 2025
Serial #2 woke up at 6:50 AM, stretched its mylar limbs, squinted at the sun (solar angle: 45°), and realized it had been cruising all night like a retired snowbird with a tailwind. Turns out it hitched a ride on the Jetstream and zoomed 1,008 miles while everyone else was sleeping—clocking a casual 68+ mph. That’s not a balloon, that’s a commuter jet with commitment issues.
Temperature’s still a brisk "don’t-touch-metal" 20-something degrees Fahrenheit, and altitude is holding strong at 35,000 feet—basically first class, minus the snacks. It's now halfway across the Atlantic, heading for what looks like a beach day in Western Sahara or maybe Mauritania. That’s the same neighborhood where Serial #1 washed up, so maybe there’s a balloon reunion planned. If it keeps floating like a champ, we should get answers in about two days. Or not. It’s a balloon—we don’t control its social calendar.
Day 3
2:45 PM, April 15, 2025
The last message from our sky-hobo came in at 1:30 PM. Since rolling out of bed this morning, it’s cruised 343 miles at a chill 60 mph, which is basically speed-walking for the upper atmosphere. Still flying at 35,500 feet like it paid for extra legroom. Temps are hovering somewhere between "meh" and "where are my gloves?"
9:50 AM, April 15, 2025
It checked in earlier at 8:10 AM with a chipper solar angle of 43°, floating just under 36,000 feet, and basking in a balmy 18°F. Before that? Radio silence. For 16 hours and 40 minutes, we heard nothing while it cruised 861 miles like a stealth blimp. When it finally phoned home, it was hanging out about 400–500 miles south of Bermuda. No triangle incidents... yet.
Day 2
4:00 PM, April 14, 2025
Today’s final postcard came in at 3:20 PM. Six hours of flight time, averaging 54 mph like a breezy scooter ride. Altitude? 35,499 feet. Temperature? -10°F, or as we call it, “NOPE degrees.” It was last seen northeast of Freeport, Bahamas, possibly looking for a Piña Colada. Solar angle’s staying steady in the low 40s—whatever that means to a balloon.
9:20 AM, April 14, 2025
Our helium hero emerged from its power nap west of Cape Coral, Florida, after ghosting us overnight. It floated 697 miles during downtime—probably listening to whale songs and pondering the meaning of lift. Now cruising above 35,000 feet like it's got somewhere to be. Spoiler: it doesn’t.
Day 1
6:00 PM, April 13, 2025
Serial #2’s last check-in was at 4:30 PM. Since its morning debut at 10:30 AM, it’s floated 271 miles, basically doing a scenic tour. The average temperature? 33°F—chilly, but not enough to freeze its dreams. Altitude? 33,083 feet. Weather nerds say the jet stream might give it a turbo boost eastward tonight. Stay tuned for high-altitude drama.
10:39 AM, April 13, 2025
Two hours after launch, and it’s already in Mexican airspace—clearly hates staying local. Nearly 31,000 feet up and crawling along at 30 mph, like it's sightseeing on a Segway.
9:25 AM, April 13, 2025
Still waiting on a signal. Possibly getting its bearings, or just being dramatic. Classic balloon.
8:15 AM, April 13, 2025
Launch day! Tom and Jan (AA5JH) showed up bright and early to the launch site. Winds were trying to photobomb the process at 8 mph, and Leo (WW2LL)’s eternal nemesis—mosquitoes—came in swarms. Jan, ever prepared, rocked a mosquito net suit like a fashion-forward beekeeper. Tom, however, toughed it out like a champ (with bonus itching). Despite the blood sacrifice, the balloon launched smoothly, climbing to 400 feet in two minutes and heading northwest at 20 mph.
Up, up, and away—with style.