ESA JUICE Mission JUpiter ICy moons Explorer which is planned for launch in 2022 would be consisted of 11 science instruments. For one of them, SWI (Submillimetre Wave Instrument), the dedicated Radiator was designed due to requirement for low operational temperature of crucial instrument subsystem. Located outside of the spacecraft and facing the Deep Space; exposed to highly radiative environment and high temperature gradients between Earth, Venus and Jupiter orbits; robust against launch vibrations; light-as-possible and optimized to provide maximal thermal efficiency. The design solution, which would successfully fulfill these often counteracting requirements occurred to be non-trivial. Presented design approach shows the balanced and optimized response for initial requirements, including the description of thermal performance modelling using ESATAN and structural FEM analysis calculated in NASTRAN.
ATHENA is a Large high energy astrophysics space mission selected by ESA in the Cosmic Vision 2015-2025 Science Program. It will be equipped with two interchangeable focal plane detectors: the X-Ray Integral Field Unit (X-IFU) and the Wide Field Imager (WFI). Both detectors require x-ray transparent filters to fully exploit their sensitivity. In order to maximize the X-ray transparency, filters must be very thin, from a few tens to few hundreds of nm, on the other hand, they must be strong enough to survive the severe launch stresses. In particular, the WFI OBF, being launched in atmospheric pressure, shall also survive acoustic loads. In this paper, we present a review of the structural modeling performed to assist the ATHENA filters design, the preliminary results from vibration and acoustic tests, and we discuss future activities necessary to consolidate the filters design, before the preliminary requirement review of the ATHENA instruments, scheduled before the end of 2018.
The Wide Field Imager (WFI) is one of the two instruments of the ATHENA astrophysics space mission approved by ESA as the second large mission in the Cosmic Vision 2015-2025 Science Programme. The WFI, based on a large array of depleted field effect transistors (DEPFET), will provide imaging in the 0.2-15 keV band over a 40’x40’ field of view, simultaneously with spectrally and time resolved photon counting. The WFI detector is also sensitive to UV/Vis photons, with an electron-hole pair production efficiency in the UV/VIS larger than that for X-ray photons. Optically generated photo-electrons may degrade the spectral resolution as well as change the energy scale by introducing a signal offset. For this reason, the use of X-ray transparent optical blocking filters (OBFs) are needed to allow the observation of X-ray sources that present a UV/Vis bright counterpart. The OBFs design is challenging since one of the two required filters is quite large (~ 160 mm × 160 mm), very thin (< 200 nm), and shall survive the mechanical load during the launch. In this paper, we review the main results of modeling and characterization tests of OBF partially representative samples, performed during the phase A study, to identify the suitable materials, optimize the design, prove that the filters can be launched in atmospheric pressure, and thus demonstrate that the chosen technology can reach the proper technical readiness before mission adoption.
The planned filter and calibration wheel for the Wide Field Imager (WFI) instrument on Athena is presented. With four selectable positions it provides the necessary functions, in particular an UV/VIS blocking filter for the WFI detectors and a calibration source. Challenges for the filter wheel design are the large volume and mass of the subsystem, the implementation of a robust mechanism and the protection of the ultra-thin filter with an area of 160 mm square. This paper describes performed trade-offs based on simulation results and describes the baseline design in detail. Reliable solutions are envisaged for the conceptual design of the filter and calibration wheel. Four different variant with different position of the filter are presented. Risk mitigation and the compliance to design requirements are demonstrated.