The termination of rocket experiments at Cuxhaven, in northern Germany, is a topic around which a deal of suspicion has grown. It is the subject of a conspiracy theory regarding the reasoning behind the decision to stop the experimentation.
On May 7, 1964 at a mail rocket show of Gerhard Zucker near Braunlage one rocket exploded shortly after launch at an altitude of a few metres and killed three people in the spectator crowd, which had too little security distance from the launchpad. Gerhard Zucker did not cooperate with any of the experimenters as the Hermann-Oberth-Gesellschaft mbH launching rockets at Cuxhaven. In fact he was called a bungler by members of the Hermann-Oberth-Gesellschaft.
The termination of rocket experiments at Cuxhaven performed by the "Seliger Forschungs- und Entwicklungsgesellschaft mbH" and the "Hermann-Oberth-Gesellschaft mbH" and some other experimentators in June 1964 was officially caused by a fatal accident at a show of mail rockets of Gerhard Zucker on May 7, 1964 on the Hasselkopf mountain near Braunlage. Indeed Gerhard Zucker did not cooperate with the "Seliger Forschungs- und Entwicklungsgesellschaft mbH", the "Hermann-Oberth-Gesellschaft mbH" and the other rocket developers who, from 1957 until 1964, launched 500 rockets in many sizes at Cuxhaven.
However the Hermann-Oberth-Gesellschaft mbH had a good reputation with their insurers, because all flights were done without any accidents and the security levels applied were high.
In addition, whilst the rockets demonstrated were not equipped with warheads and did not contravene the Allied laws concerning the development of military rockets in Germany, they were easily transformable to rocket weapons which would violate those laws. Therefore this flight demonstration was very controversional, and some protests by the Soviet Union occurred.
The believed reason for the termination of rocket experiments at Cuxhaven might be the flight demonstration of militarily usable rockets of the Seliger Forschungs - und Entwicklungsgesellschaft mbH to military staff from non-NATO countries, on December 5, 1963. Because no Allied laws were directly violated by these launches, the rocket experiments at the area of Cuxhaven, which were because of rocket mail launches very popular by tourists, continued at first. However, they were watched with great suspicion, because officials feared that under the mask of mail and sounding rockets, military missiles would be developed.
The arguments with which the rocket experiments in the area at Cuxhaven were banned in June 1964 showed some inconsistencies; although the accident at Braunlage was a typical accident with explosives on the ground, air traffic law rather than not the law for handling explosives was applied to explain the ban. (In fact it this ban was not a total ban of rocket experiments at Cuxhaven. Rocket experiments with flight altitudes below 100 metres were still allowed, but such experiments were of no practical interest at all.)
Interestingly, it was said in June 1964 that the rocket launches at Cuxhaven could continue after new security measures were set up, but this was not done.
Another interesting fact is that the Hermann-Oberth-Gesellschaft and the Seliger Forschungs- und Entwicklungsgesellschaft mbH were not allowed to collaborate in Germany's contribution to the ESA projects, although both organizations had a lot of practical experience in launching and designing rockets.