The eRosita project

Was dark energy stronger or weaker in the past than it is today? The German X-ray telescope eROSITA (extended Roentgen Survey with an Imaging Telescope Array), built under the leadership of the Max Planck Institute for Extraterrestrial Physics in Garching, aims to shed light on this mystery.

Telescope and space probe

Seven parallel mirror systems form the optics of the X-ray telescope. Their combination of light-collecting area, field of view and resolution is unmatched to date. At the focal point of each mirror system is a highly sensitive CCD camera that was developed specifically for eROSITA. In addition to the Max Planck Institute for Extraterrestrial Physics in Garching, the universities of Tübingen, Erlangen-Nuremberg and Hamburg, as well as the Leibniz Institute for Astrophysics Potsdam, are also involved in the development and scientific support of the telescope. (Source: DLR/German Space Agency)

Each mirror system consists of 54 concentrically arranged shells. The baffle (English: ‘baffle’) is similarly composed of 54 individual rings. These components are manufactured from INVAR sheets using a process developed jointly by MPE and LaserJob: the sheets are precisely cut, bent, mounted on cylinders and then welded.

The baffle is subject to particularly high requirements in terms of dimensional accuracy. The roundness tolerance to be maintained is ±0.05 mm, and the position tolerance is 0.04 mm. These demanding specifications were successfully achieved through close cooperation.

The biggest challenge in processing the components was maintaining their roundness after the welding process without damaging the surface of the baffle shells.

These two aspects were crucial to the functionality of the components, as they had a significant impact on the overall productivity and quality of the end product.

During the course of the project, we carried out numerous welding tests in order to meet the high requirements for roundness. We encountered various difficulties, but finally achieved a breakthrough with a meander-shaped cut. This technique, combined with partial interlocking welding of the sheets, proved to be extremely effective.

Specially developed devices were used to further increase quality and efficiency. These not only optimised the welding process, but also protected the sensitive surfaces of the baffle shells from damage. Ultimately, this combination of innovative processes and precise technology enabled the components to meet the high standards set for us by the task.

In summary, the project was an impressive achievement in collaboration with the Max Planck Institute in the field of modern manufacturing technology, combined with craftsmanship that demonstrates how targeted adjustments and innovative approaches can efficiently overcome even the greatest challenges.

Project management:

Max Planck Institute for Extraterrestrial Physics

Giessenbachstraße D  

85741 Garching

Further information:

Max Planck Institute for Extraterrestrial Physics/MPE

Flyer

DLR/ German Aerospace Centre