High altitude ballooning is a hobby that explores the region of the Earth’s atmosphere called “near space.” This region is between 65,000 and 325,000–350,000 feet and at these altitudes, it near space more like earth orbit than the surface of the earth. Air pressure in near space reaches 99% of a vacuum or better and air temperatures drop to a low of -60 degrees F or colder. Near space cosmic radiation is also over 100 times greater than at sea level.
Amateur radio operators have taken part in these experiments. Called Amateur Radio High Altitude Ballooning (ARHAB), it has been referred to as the “poor man’s space program.” ARHAB allows amateurs to design functioning models of spacecraft and launch them into a space-like environment.
One of the payloads for an ARHAB flight is an amateur radio transmitter. It uses the Automatic Position Reporting System (APRS) to transmit telemetry data that allows tracking of the flight to its landing area for recovery. Non-APRS equipped payloads can use direction finding techniques to track the flight. In addition to amateur radio, other payloads include sensors, data loggers, cameras, amateur television (ATV) transmitters and other scientific experiments.
The Great Plains Super Launch (GPSL) in Omaha, NE hosts a large gathering of ARHAB groups every year.