Solar Ultraviolet Network (SUN): An interferometric investigation of the fundamental solar astrophysical scales

Present Solar telescope projects, on ground or in Space (like the Orbiting Solar Laboratory) are limited in their ambitions to visible wavelengths and to spatial resolutions not better than a tenth of an arcsec. The Solar Ultraviolet Network (SUN) proposal presented in this paper, is an interferometric concept capable of observations with a spatial resolution better than 0.013” (10 km) on the Sun, in the UV range. Based on Stabilized Interferometry principles it consists in 4 telescopes of 20 cm diameter aligned non-redundantly on a 2 m baseline. Despite its size (2.1 x 1.0 x 0.7 m) and its intrinsic complexity, SUN would be perfectly suited for use on the Space Station, when implemented on a pointing platform of performances comparable with the Instrument Pointing System (flown on Spacelab2). The remarkable capabilities of the SUN instrument, resulting from its “compact” non-redundant configuration of telescopes, allow high resolution imaging on a 2 x 2 arcsec²field (and with a dynamic on the reconstructed images superior to 100 for phase stabilities ≥ λ/10), on the Solar disk (granulation, flares and micro-flares, prominences and filaments), or at the limb and above, across coronal loops.