The telescope and the double Fabry-Pérot interferometer for the ADAHELI solar space mission

ADvanced Astronomy for HELIophysics (ADAHELI) is a Small Mission to study the structure and fast dynamics of the low solar atmosphere, performing Visible-NIR monochromatic and broad-band observations. The mission will achieve millimeter full disk observations as well. The ADAHELI Team has succesfully completed, in December 2008, the Phase A study awarded by the Italian Space Agency (ASI). The Interferometer for SOlar Dynamics (ISODY), on board the ADAHELI satellite, comprises a Gregorian telescope and its focal plane suite. The advanced design focal plane suite uses fast CMOS cameras for investigating photospheric and chromospheric fast dynamics and structure. ISODY is equipped with a pioneering focal plane suite composed of a spectral channel, based upon a tandem of Fabry-Perot interferometers operating in the visible-NIR spectral region, a broad band channel for high resolution imaging, and a correlation tracker used as an image stabilization system. ADAHELI's mission profile has been tailored to limit the spacecraft' s radial velocity in the Sunward direction, to not exceed ±4 km/s, during 95% of the yearly orbit, to allow a continuous use of the on-board interferometer.