New perspectives in solar coronagraphy offered by formation flying: from PROBA-3 to Cosmic Vision

Abstract

Formation flying opens new perspectives in solar physics, and allow to conceive giant, externally-occulted coronagraphs using a two-component space system with the external occulter on one spacecraft and the optical instrument on the other spacecraft at a distance of hundred meters. Conditions close to those of a solar total eclipse can then be achieved offering the capability of imaging the solar corona down to the limb at very high spatial resolution. ASPIICS (Association de Satellites Pour l'Imagerie et l'Interférométrie de la Couronne Solaire) is a mission proposed to ESA in the framework of its PROBA-3 demonstration program of formation flying which is presently in phase A. ASPIICS is a single coronagraph which will perform both high spatial resolution imaging of the solar corona as well as 2-dimensional spectroscopy of several emission lines from the coronal base out to 3 R&beye; using a Fabry-Pérot <i>étalon </i>interferometer. The classical design of an externally-occulted coronagraph is adapted to the formation flying configuration allowing the detection of the very inner corona as close as 0.01 R&beye; from the solar limb. Super-ASPIICS is an even more ambitious instrument part of the scientific payload of HiRise, the High Resolution Imaging and Spectroscopy Explorer proposed to ESA in the framework of its Cosmic Vision program. With an increased inter-satellite distance of 280 m, an aperture of 300 mm, a spectral domain extending from the ultraviolet to the near-infrared, and spectroscopic capabilities, Super-ASPIICS will offer unprecedented diagnostic capabilities, including the measurement of coronal magnetic fields.