The stray light baffle for the ARRAKIHS mission

ARRAKIHS is an ESA mission dedicated to observing dwarf galaxies and stellar streams. Its objective will be to test the standard cosmological model, particularly regarding the nature of dark matter. It will use four telescopes operating in the visible and near infrared spectral ranges. As they will observe ultra-low brightness objects, an extreme level of stray light control is necessary. A large external baffle is necessary to prevent out-of-field light from entering the telescope, with an extreme stray light rejection down to 10-11. This paper will discuss the design of this baffle. We will present the design trade-offs, as different possible baffle architectures were considered. Ultimately, the selected architecture consists in developing one baffle for two telescopes, hence a total of two baffles are used on the payload. A multi-stage baffle is developed, in the heritage of the CoRoT baffle which is seen as one of the best ever designed. Moreover, we will discuss the reflections on the test setup which will be implemented for validating the design on a prototype.