The grain silos in the port of Assen, Hekmans Boô in Schoonebeek, the artwork Broken Circle/Spiral Hill in a sand excavation near Emmen, the Holthersluis near Beilen, the polder pumping station at Peize, De Berk Molen near Barger-Compas and the ‘small’ radio-telescope at Dwingeloo.
What do they have in common? They are all new protected provincial monuments. Every Sunday we put one in the spotlight.
The telescope at the former Planetron in Dwingeloo was once not a telescope at all but a radar, war stress: the Würzburg Riese. Telefunken in Berlin was already very far in the radar area. The Zeppelin factories in Friedrichshafen built the parabolic mirror and so they designed a radar antenna with which they could follow aircraft up to 70 kilometers away.
Air defense of the Atlantic Wall
In the Second World War, Nazi Germany built a line of defense along the entire coast from Norway to Spain. The Atlantic Wall. There, 1500 Würzburg Riese RadarieNennes came on. Along the Dutch coast were about forty of such radar installations. Usually purple: one for following the enemy aircraft and one for guiding their own night hunters.
Curious citizens were asked what this was always heard from the Germans: “They are very sensitive microphones that the English planes are coming.” The radars have contributed a lot to the loss of many allied planes above Western Europe.
After the war, most radar installations disappeared in melt ovens. Some were saved, converted and used for scientific purposes, including at Zendstation Radio Kootwijk. Under the leadership of radio engineer Lex Muller, they were converted into radio telescopes. So star viewers.
This made the first measurements with radio waves from the universe. Because the Utrecht astronomy student Henk van de Hulst detected by the Leiden astronomer Jan Oort- had already figured out in 1944 that hydrogen atoms in the universe broadcast very weak radio waves. So we needed very good ears to ‘see’ them.
Muller’s ears worked. The Dutch astronomers and technicians in Radio Kootwijk ‘heard/saw’ the first pieces of our Melkweg in 1951. After that, systematic research into the structure of the Melkweg started in the Netherlands and the first map of our Milky Way System was made in 1953.
That success provides Dutch astronomy and lays the foundation to build the world -famous 25 -meter radio telescope in Dwingeloo (1956) for more detailed research into the Melkweg. That large telescope on the edge of the Dwingelderveld is also a monument and retired. But the Camras Foundation still does observations and discoveries with it.
From the beginning (in the 1950s), the Würzburg-Riese’s converted into telescopes at Radio Kootwijk had a lot of problems with the radiation from the broadcasting station with which the Netherlands maintained radio traffic (first telegraphy and later calling) with the Dutch East Indies. Around 1955 the antennas were moved to Dwingeloo for Melkweg investigation and Nederhorst den Berg for observations of the sun.
For research into radio astronomy, Drenthe was consciously chosen, due to the favorable conditions of non-built-up areas and little light and sound pollution. That was the start of Dwingeloo and Westerbork as a top world-class research institute Astron with the large radio telescope of Dwingeloo, the telescopes row at former Westerbork camp and the construction of the Lofar telescope throughout Western Europe.
Around 1983, the Würzburg Riese Radiotelescoop in Nederhorst den Berg retired again and also moved to Drenthe: to the Volkssterenwacht Drenthe in Emmer-Compascuum, to make observations for and with the public.
The Würzburg Riese was eventually donated by the Volksstrenwacht to the newly built Planetron in Dwingeloo and was put into use in Dwingeloo in 1990 together with an observatory, cinema, planetarium, exhibition space and the largest optical telescope in the Netherlands that was available to the public. Purpose of all this: bring astronomy and space travel closer to the general public.
Due to decreasing visitor numbers and aging, the plug was drawn from the Planetron information center at the end of 2014. The Planetron has been empty since that time and then slowly fell into disrepair, there were only star views. In 2020, the Planetron was given a new interpretation and was converted into a ‘tourist house’, with the new user recreational company Drenthe, Marketing Drenthe and Vital Holiday Parks.
But the ‘small’ radio telescope of Dwingeloo was rusting unemployed in the meantime. The cabin of the Würzburg Riese has been robbed between 2019 and 2021 and the telescope is no longer working. The small radio telescope of Dwingeloo is retired for the fourth time in his life.