The stereo camera on the BepiColombo ESA/JAXA mission: a novel approach.

The stereo camera (STC) is one of three channels of the spectrometer and imagers for Mercury Planet Orbiter BepiColombo Integrated Observatory SYStem (SIMBIOSYS), which will be on board the Mercury Planetary Orbiter of the ESA mission BepiColombo. SIMBIOSYS includes also an high resolution imaging channel (HRIC), providing images at spatial resolution of 5m/pixel at the periherm, and the VIS-NIR spectrometer (VIHI) that will provide the global mapping of the Mercury’s surface in the spectral range 400–2200 nm, with a spectral sampling of 6.25 nm, and the spatial resolution of 400m/pixel at the periherm. The main scientific objective of STC is the global mapping of the entire surface of the Mercury in 3D and colors with a scale factor of 50m/pixel at the periherm. It will allow to generate the digital terrain model (DTM) of the entire surface improving the interpretation of morphological features at different scales and topographic relationships. The harsh environment of the Mercury will strongly affect the functionalities and performance of the instruments reducing the resources allocated to the payload. Even for the stereo camera, as for most of the instrument on board BepiColombo, a novel design had to be considered. We have implemented an original optical design, modifying a classical configurations, and a new technique of acquiring the stereo pairs for generating the DTM of the surface. The new technique will have an impact on the software chain generating the DTM and on the observation strategy. The stereo camera consists of two channels, looking at the surface at ±20◦ from the nadir direction, converging on the same bidimensional focal plane assembly, with no mechanical movable parts. The configuration of the focal plane assembly allows to apply the push-frame technique to acquire the stereo images.