The ADAHELI Solar Mission

DAHELI (Advanced Astronomy for HELIOphysics) is an Italian Space project for the investigation of solar photospheric and chromospheric dynamics, via high-resolution spectro-polarimetric observations in the near-infrared spectral range. The mission has been financed for phase A study in the framework of ASI Italian Space Agency Small Missions Program call of September 2007. Four fields have been selected to highlight the specific benefits of ADAHELI scientific payload: 1) Photospheric and chromospheric dynamics and structure, 2) Emergence and evolution of solar active regions and solar irradiance, 3) Chromospheric and corona heating and turbulence, 4) Solar flares in the millimeter wavelength region. The principal science instrument, ISODY, is a 50 cm solar telescope equipped with an innovative Focal Plane Suite composed of a spectro-polarimetric imager, based upon two Fabry-Perot interferometers operating in the NIR regions around 845nm and 1083nm, a broad band imager, and a correlation tracker used as image stabilization system. Designed Mission Profiles for ADAHELI intend to achieve continuous high-spectral and spatial resolution observations of the Sun for a routine duration of 4 hours with a goal to be extended to 24 hours. ADAHELI also carries MIOS, a millimeter wavelengths radiometer operating at around 90 GHz for flare detection. The ADAHELI payload's instrument suite integrates and complements, without overlap, the present major objectives of ESA, NASA and the International Living with a Star program, in particular Solar Dynamics Observatory, PICARD, Solar Orbiter, and the Solar Probe missions. Proposals for optional instruments are also under evaluation: DIMMI-2h, a double channel MOF based full disk imager operating at 589nm and 770nm, allowing high temporal resolution velocity and magnetic field measurements; EISR a two channel spectrometer operating in the 50-130 nm wavelength range, and NPA, an in-situ Neutral Particle Analyzer to detect Energetic Neutral Atoms (ENA). Science objectives related to optional instruments include: solar high and low-degree p modes oscillations, EUV solar structures and variability, solar gravitational red-shift measurement, detection of ENA originating from the plasma region in the Earth's magnetosphere and undergoing reflection from the Earth's atmosphere.