I found these two pictures in the Russian Novosti Kosmonavtiki forum. They were taken in the aeronautics museum of Speyer, in Germany. The poster wonders what it is.
my opinion is that it could be a model of the (West) German-US Advanced Cooperation Project Jupiter probe of the 60s. By about 1968 it was deemed beyond German technology of the time and was scaled down to the Helios solar probes.
Any idea anyone?

correct Paolo, that's the bus of the 750 kg US-German probe, which was designed by Bölkow.

more info re-linked from the Novosti Kosmonavtiki forum:

Sorry I don't speak German, but I would be interested in a translation.
see also Flight International for 1966
http://www.flightglobal.com/pdfarchive/vie...20-%201381.html
and
http://www.flightglobal.com/pdfarchive/vie...20-%201382.html

I have found more info on this as well as other fascinating projects of the 60s in this pdf:
http://ntrs.nasa.gov/archive/nasa/casi.ntr..._1968018866.pdf

Awesome. US space probes just didn’t have enough spheres on them.

That is because, unlike Soviet spacecraft, they weren't pressurized.