The Atmospheric Remote-sensing Infrared Exoplanets Large-survey (ARIEL) payload electronic subsystems

The ARIEL mission has been proposed to ESA by an European Consortium as the first space mission to extensively perform remote sensing on the atmospheres of a well defined set of warm and hot transiting gas giant exoplanets, whose temperature range between ~600 K and 3000 K. ARIEL will observe a large number (~500) of warm and hot transiting gas giants, Neptunes and super-Earths around a range of host star types using transit spectroscopy in the ~2-8 μm spectral range and broad-band photometry in the NIR and optical. ARIEL will target planets hotter than 600 K to take advantage of their well-mixed atmospheres, which should show minimal condensation and sequestration of high-Z materials and thus reveal their bulk and elemental composition. One of the major motivations for exoplanet characterisation is to understand the probability of occurrence of habitable worlds, i.e. suitable for surface liquid water. While ARIEL will not study habitable planets, its major contribution to this topic will results from its capability to detect the presence of atmospheres on many terrestrial planets outside the habitable zone and, in many cases, characterise them. This represents a fundamental breakthrough in understanding the physical and chemical processes of a large sample of exoplanets atmospheres as well as their bulk properties and to probe in-space technology. The ARIEL infrared spectrometer (AIRS) provides data on the atmospheric composition; these data are acquired and processed by an On-Board Data Handling (OBDH) system including the Cold Front End Electronics (CFEE) and the Instrument Control Unit (ICU). The Telescope Control Unit (TCU) is also included inside the ICU. The latter is directly connected to the Control and Data Management Unit (CDMU) on board the Service Module (SVM). The general hardware architecture and the application software of the ICU are described. The Fine Guidance Sensor (FGS) electronics and the Cooler Control Electronics are also presented.