The Advanced Technology Solar Spectroscopic Imager—a novel experiment employing a transition-edge sensor to probe the soft X-ray solar corona

The Advanced Technology Solar Spectroscopic Imager (ATSSI) is a sounding rocket-borne experiment that will employ a Transition-Edge Sensor (TES) placed at the focus of a Wolter-I mirror to study large active region loops in the solar corona. The TES instrument will operate in the ∼500–1500 eV EUV/soft X-ray bandpass, obtaining ∼3 eV energy-resolved spectra at ∼6.25 arcsec image resolution with a count rate of ∼1000 photons/sec/pixel. Over a typical observation period of ∼360 sec, we will raster scan over a 0.6×0.6 arcmin field of view to obtain a 6×6 pixel image containing true EUV/soft X-ray spectroheliograms of a solar active region. Using these observations, we can directly determine composition, electron density and thermal differential emission measure of large active region loops in order to constrain models of heating mechanisms and accurately measure the thermal morphology of these structures. In the current analysis, we present an initial instrument concept and discuss some of the mission science goals.