The calibration and testing of the eROSITA X-ray mirror assemblies

Burwitz, V.; Predehl, P.; Friedrich, Péter; Bräuninger, H.; Eder, Josef; Pfeffermann, E.; Burkert, Wolfgang; Dennerl, K.; Hartner, Gisela; Menz, Benedikt; Fürmetz, Maria; Valsecchi, Giuseppe; Marioni, Fabio; Grisoni, Gabriele

doi:10.1117/12.2056739

Cited by 11 publications

(6 citation statements)

References 12 publications

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“…The whole telescope assembly is mounted to the spacecraft on three points by means of a hexapod for mechanical decoupling. Each telescope has a focal length of 1.6m and consists of a mirror assembly with 54 electroformed nickel shells with Wolter-1-geometry and an X-ray baffle [3], a CCD camera in its focus [2] and an electronics box for data processing. Apart from that, a complex passive cooling system for cameras and electronics needs four radiators at the telescope's outer side as shown in Figure 1.…”

Section: Instrument Descriptionmentioning

confidence: 99%

The x-ray telescope eROSITA: qualification of the thermal control system

et al. 2014

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eROSITA is the core instrument on the Spektrum-Röntgen-Gamma (SRG) mission, scheduled for launch in 2016. The main tasks of the thermal control system are heating of the mirror modules, cooling of the camera electronics, cooling of the CCD detectors and temperature control of the telescope structure in general. Special attention is paid to the camera cooling, since it is the most critical one. The complex assembly with the sevenfold symmetry of the eROSITA telescope requires an innovative design. Large distances and a very low operating temperature (-90°C to -100°C) place high demands on the cooling chain. In total, three different types of low-temperature ethane heat pipes are used to transport the heat from the cameras to two radiators outside the telescope structure. Extreme environmental temperature gradients with the Sun on the one side and the cold space on the other present a real challenge not only to the camera cooling systems, but to the overall thermal control.A thermal model of the complete telescope was used to predict the thermal behavior of the telescope and its subsystems. Through various tests, this model could be improved step by step. The most complex test was the space simulation test of the eROSITA qualification model in January 2013 at the IABG facilities in Ottobrunn, Germany.About 50 heaters, a liquid-nitrogen-cooled chamber and a Sun simulator provided realistic mission conditions. Approximately 200 temperature sensors monitored the relevant temperatures during the test. The results were predominantly within the predicted intervals and therefore not only verified the complete concept but also enabled a further refining of the thermal model. This, in turn, allows for reliable predictions of the thermal behavior during the mission. Some deviations required minor changes in the final design which were implemented and re-qualified in a separate test of the thermal control system flight model in March 2014 in the PANTER test facility of MPE. The results of both tests will be presented in this contribution.

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Section: Instrument Descriptionmentioning

confidence: 99%

The x-ray telescope eROSITA: qualification of the thermal control system

et al. 2014

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“…The X-ray telescope of eROSITA [3] consists of 7 identical and co-aligned mirror modules, each with 54 nested Wolter-1 mirror shells [1,2]. An X-ray baffle in front of each mirror entrance protects against X-ray stray light from single reflections from the hyperbola part of the Wolter mirrors.…”

Section: Introductionmentioning

confidence: 99%

The eROSITA x-ray baffle

et al. 2014

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The X-ray baffle is an important part of the eROSITA mirror assembly as it reduces the stray light caused by single reflections at the Wolter 1 Mirrors by more than 90%. The stray light problem and possible solutions were analyzed by ray-tracing resulting in a trade-off between effective stray light protection and avoidance of vignetting. Possible design alternatives were considered and the influences of manufacturing tolerances were studied. Other than for XMM, the eROSITA X-ray baffle could not be realized as sieve plates; instead a system of co-aligned "baffle rings" was mounted onto each of the mirror modules. The mechanical design is based on concentric Invar foils fixed by an own spider. The complete X-ray baffles were finally mounted to the mirror module while the alignment was controlled by optical means.

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“…This information is then used to guide the robot-assisted alignment sequence. This alignment and integration process has been successfully adopted in the past by Media Lario for the integration of the Mirror Modules of many X-Ray Telescopes, such as Beppo-SAX, JET-X, SWIFT, XMM-Newton and eROSITA [8].…”

Section: Introductionmentioning

confidence: 99%

ATHENA Telescope: alignment and integration of SPO mirror modules

Valsecchi

Marioni

Bianucci

et al. 2019

International Conference on Space Optics — ICSO 2018

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ATHENA (Advanced Telescope for High-ENergy Astrophysics) is the next high-energy astrophysical mission of the European Space Agency currently planned to be launched in the early 2030s, as part of its Cosmic Vision program, on the scientific topic of "Hot and Energetic Universe". The optics technology is based on the Silicon Pore Optics (SPO). About 678 SPO mirror modules will have to be integrated and co-aligned onto the optical bench of the Mirror Assembly Module (MAM) of ATHENA. This activity will have to be completed in about two years. Media Lario leads an industrial and scientific team that has developed the process to align and integrate the SPO Mirror module with an accuracy better than 1 arcsec. The process is based on position of the centroid of the point spread function produced by each mirror module when illuminated by a collimated planewave at 218 nm taken at 12 m focal length. Experimental tests, using two SPO mirror modules, and correlation with X-ray measurement at the PANTER test facility in Münich have demonstrated that this process meets the accuracy requirement. It was also demonstrated, that a mirror module can be removed again from the MAM, and re-installed, without compromising the adjacent mirror modules. This technique allows arbitrary integration sequence and integration of two Mirror Modules per day. Moreover, it enables monitoring the telescope point spread function during the whole integration phase.

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The calibration and testing of the eROSITA X-ray mirror assemblies

Cited by 11 publications

References 12 publications

The x-ray telescope eROSITA: qualification of the thermal control system

The x-ray telescope eROSITA: qualification of the thermal control system

The eROSITA x-ray baffle

ATHENA Telescope: alignment and integration of SPO mirror modules

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