Four Weeks after the Fact

#10 Meppen – Marienheide
Vaisala RS41-SGP / N2240508 / 07.01.2019 0800Z
🔗 in storage
🔗 individual transport

The Meppen morning sonde from 07.01. first wanted to approach me exactly, but then landed about 10 km air-line distance from my QTH. From the TH I took the RB to Marienheide, which only has hourly service, while the sonde was still in the air. The last prediction I had on the train pointed to a somewhat more northerly landing, and the bus in this direction departed at the same time as the train arrived. With a few minutes old prediction I ran to reach this bus, which also only departs hourly, and managed to do so. Unfortunately, as soon as I checked the last data of the sonde, it turned out that it had landed a little more to the south, and I was driving in the wrong direction. Half as bad, the bus in the opposite direction arrived in 15 minutes. That gave time to forge the plan. The landing area around Dürhölzen had many small woods and meadows and because ON-1 was down, I didn’t know exactly if the landing place was in the forest. A school bus took me there, back I would have to walk the five kilometres to the station. What one one does for his sonde

After a snack at the bakery I started. As I was allowed to learn here in the village the bus driver knows every child by name, and so I was of course the one sticking out. After I had explained my mission and pulled out my laptop to see if the probe was already audible, the crowd was highly fascinated by my Moxon made from Lego-Technic. I first had reception in the village, and unfortunately the probe had landed in the forest.

There arrived the parachute could clearly be seen with large balloon reaminings in a leafy tree above the forest road in a height of 6-8 m. There was no trace of the sonde. The GPS data pointed to an adjacent spruce plantation in which the string disappeared. DFing with the Moxon and SDR didn’t work, moreover the landing area was a valley, everywhere reflections. My lack of experience adds to that. Frustrated, I went on the journey home, the drizzle matched my mood.

At home I evaluated the GPS data of about 20 minutes again, and noticed a very high variance. The averaged values were much closer to the forest path than expected, but fluctuated by about 50 m. Since the sonde was definitely hanging in a tree, the bad GPS reception indicated a position in the middle of the branches.

Today the weather was perfect and I undertook a follow-up check with a friend who is into fishing. The parachute had disappeared and was not to be seen on the ground under the snow, probably it had already fallen down and been taken away. A rough optical check around the interpolated position didn’t help, and at the end of the sonde string, which we caught, was nothing. Before we gave up, a thorough optical check was performed. And in fact, not far from the path, the sonde was lying on the snow. So it could only have come down in the last few days. The sensor arm was in a very poor shape, but it didn’t show any error when turned on.