Observatory, Germany

Planetarium, Astronomical observatory, Office, Exhibition space, Solingen DE, Project Team: René van Zuuk, Peter Hagelaar, Ján Ertl, Anja Rademaker, Client: Sternwarte Solingen, Design: 2011, Area: 2.000 m², Volume: 12.000 m³

In the city of Solingen, located in the Ruhr area of Germany, the local observatory, in collaboration with the regional industrial heritage organization, has organized a closed competition for the redevelopment of an old spherical gas container (Kugel-Gasbehälter). The strong industrial character and historical significance of the container, allows the new project to fit in with the surrounding buildings, invaluable to the industrial heritage.

The gas tank is located on the edge of a residential area, near the railway line. From the adjacent station, you can see the top half of the sphere through the treetops. In addition to the steel sphere, spanning 26 meters in diameter, the characteristic structure also consists of eleven load-bearing columns, resting on a 3-meter high concrete foundation.

The original design was pragmatic in its approach. The sphere was chosen as the most efficient model, as it is able to store the most, by using the least amount of space. In the creation of the new design, it is not necessary to retain the characteristics of the old use at all costs, but it is important to implement the new elements with the same efficiency. Only then will a volume be created that will perfectly serve the new function, without the old structure design being sidelined.

The new functions to be included in the Galileum, consist of an entrance with a back office, a presentation room for 80 people, an exhibition room with a half-sphere planetarium, and an observatory. With optimum use of the old structure, most functions will be placed within the sphere. At the base, an entrance has been carved in-between the foundations, that leads to the entrance hall. On the other side of the foundations, the offices, presentation rooms, and other general amenities have been placed. These spaces open out, onto a patio, that provides light to an otherwise sheltered area of the project. The outer part of the entrance level is then brought to the height of the foundation wall, by adding soil. This is done so that the structure can visually maintain its spherical shape. A series of stairs start from the entrance, and lead the visitor further up, through a large void in the sphere levels. There are two open exhibition spaces on the first and second floors. The third floor contains the planetarium. The observatory is at the very top of the sphere. There, a second cut in the structure creates a dome and allows the telescope to rotate without any obstruction. On top of the dome is an antenna equipped with a laser, that will draw a line in the sky on cloudy days.

All these extra functions cannot be structurally supported by the existing structure. However, we have added an additional exoskeleton, supporting the volume from the outside. There is also a steel tube in the centre, serving as an elevator shaft, that also provides structural support for the project's new uses.