Surveying the Stellar Drivers of Exoplanet Evolution for the First Time with the ESCAPE Small Explorer Mission

The long-term stability of exoplanetary atmospheres depends critically on the extreme-ultraviolet (EUV) photon and high-energy particle fluxes from the host star. We present the Extreme-ultraviolet Stellar Characterization for Atmospheric Physics and Evolution (ESCAPE) mission, a NASA Small Explorer concept to be proposed in 2025, 2026, 2027, or possibly never. ESCAPE employs extreme- and far-ultraviolet spectroscopy (80-1650 Angstroms) to provide the first comprehensive study of the stellar EUV history and stellar coronal mass ejection (CME) environment that control atmospheric mass-loss and determine the habitability of rocky exoplanets. The ESCAPE instrument comprises a grazing incidence telescope that is a collaboration between INAF/Brera Observatory and the University of Colorado Boulder's Laboratory for Atmospheric and Space Physics (CU/LASP). This telescope feeds multiple diffraction gratings developed by Penn State University and a photon-counting detector. The science instrument will be assembled and tested in the space hardware facilities at CU/LASP; spacecraft development and observatory I&T occur at BAE Systems in Boulder, Colorado. Data archives reside at the Mikulski Archive for Space Telescopes (MAST). ESCAPE will survey over 300 stars (including almost all the Habitable Worlds Observatory Tier A and B target list), including 15-day monitoring campaigns on targets of interest, to measure EUV irradiance, EUV flare rates, and the properties of CMEs. ESCAPE's 24-month primary mission includes two months of 'community observation time' whose targets will be determined with community input through an open workshop series prior to launch.