Tracking a WSPR balloon on 28 MHz off the west coast of Ireland - Apr 2024

On the 28th of November 2023, Perri Moore KD9NGV launched a Pico-Balloon from Illinois in the United States with a solar powered payload that transmits a WSPR beacon on 28.1246 MHz.

Most of the Pico-Balloons launched from the USA tend to take a path closer to about 30 degrees north of the equator and cross areas like the north of Africa and south Asia. In contrast,  the KD9NGV balloon seems to have covered a much wider area and has been reported at more northerly latitudes as shown on the map above.

By the 16th of December 2023, it had gone around the world once! By the 19th of February, it had gone around the world three times. By mid April 2024, it has gone around the globe multiple times and the red dots on the map show where it was when I received some of the WSPR signals over the last few weeks.

What caught my interest was that back on the 7th of April 2024, the KD9NGV Pico-Balloon was off the west coast of Ireland. Most of the reception reports of the WSPR transmitter are via F2-layer propagation during the daytime. When it was off the west coast of Ireland, it was at about 40,000ft (12.2kms) altitude and line of sight to my location.

As can be seen from the map above and the reports below, my first reception report on the 7th of April was at 14:10 UTC when it was about 400kms to the west. A few others reported it via F2 layer propagation but I was the main one reporting it as it tracked its way up off the west coast of Ireland.

After 17:50 UTC, I lost it but it then came into the range of GM0HBF in the Western Isles of Scotland.

It then went silent as darkness fell. Once daylight broke again on the 8th of April, it was over the North Sea and GM4WJA started to report it.

At the time of the screen grab, LA3FY/2 in Norway was hearing it and it continued then over Scandinavia. It has since crossed over Russia and at the time of writing is up over the far north of Canada.

KD9NGV Payload... The actual payload pre-launch is shown below.

The 28 MHz WSPR signal is generated by a Si5351 clock generator and the power output is just 9 milliwatts... 0.009 watts!

The antenna is a vertical half-wave dipole made of #36 enamelled wire.  The top half is from the balloon to the U4B tracker (QRP Labs) and the lower half hangs below the tracker.  Three Powerfilm MPT 3.6-75  in a vertical triangle provide the power.  The complete payload weighs 12 grams.

The balloon is described as a "silver SAG Balloon with Helium.".

In conclusion... I have noticed these WSPR pico-balloons many times on the 28 MHz band before but they are nearly always flying over some exotic location. It was just unusual to have one pass so close and be line of sight.