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.