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Analog photonic techniques can perform better than conventional digital electronics, which have significant limitations when it comes to processing fast RF signals on the fly. We show that a simple photonic architecture, based on a bi-directional frequency-shifting loop, makes it possible to calculate in real time the cross-correlation function of two broadband signals for about 200 values of their delay simultaneously. Additionally, our architecture also enables to perform spectral analysis of signals with 16 GHz instantaneous bandwidth, 100 % probability of interception, and detection electronics below 10 MSa/s.

A lack of observable quantities renders it generally difficult to confront models of Space Weather with experimental data and drastically reduces the forecast accuracy. This is especially true for the region of Earth’s atmosphere between altitudes of 90 km and 300 km, which is practically inaccessible, except by means of remote sensing techniques. For this reason auroral emissions are an interesting proxy for the physical processes taking place in this region. This paper describes two future space missions, AMICal Sat and ATISE, that will rely on CubeSats to observe the aurora. These satellites will perform measurements of auroral emissions in order to reconstruct the deposition of particle precipitations in auroral regions. ATISE is a 12U CubeSat with a spectrometer and imager payloads. The spectrometer is built using the micro-Spectrometer-On-a-Chip (μSPOC) technology. It will work in the 370–900 nm wavelength range and allow for short exposure times of around 1 s. The spectrometer will have six lines of sight. The joint imager is a miniaturized wide-field imager based on the Teledyne-E2V ONYX detector in combination with a large aperture objective. Observation will be done at the limb and will enable reconstruction of the vertical profile of the auroral emissions. ATISE is planned to be launched in mid 2021. AMICal Sat is a 2U CubeSat that will embed the imager of ATISE and will observe the aurora both in limb and nadir configurations. This imager will enable measuring vertical profiles of the emission when observing in a limb configuration similar to that of ATISE. It will map a large part of the night side auroral oval with a resolution of the order of a few km. Both the spectrometer and imager will be calibrated with a photometric precision better than 10% using the moon as a wide-field, stable and extended source. Ground-based demonstrators of both instruments have been tested in 2017 in Norway and Svalbard. Even though some issues still need to be solved, the first results are very encouraging for the planned future space missions. Data interpretation will be done using the forward Transsolo code, a 1D kinetic code solving the Boltzmann equation along a local vertical and enabling simulation of the thermospheric and ionospheric emissions using precipitation data as input.