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Multiple healing cycles of a single crack in a brittle polymer coating are achieved by microvascular delivery of a two‐part, epoxy‐based self‐healing chemistry. Epoxy resin and amine‐based curing agents are transported to the crack plane through two sets of independent vascular networks embedded within a ductile polymer substrate beneath the coating. The two reactive components remain isolated and stable in the vascular networks until crack formation occurs in the coating under a mechanical load. Both healing components are wicked by capillary forces into the crack plane, where they react and effectively bond the crack faces closed. Healing efficiencies of over 60% are achieved for up to 16 intermittent healing cycles of a single crack, which represents a significant improvement over systems in which a single monomeric healing agent is delivered.

High-resolution Airborne Wide-band Camera (HAWC[Formula: see text]) is the facility far-infrared imager and polarimeter for SOFIA, NASA’s Stratospheric Observatory for Infrared Astronomy. It is designed to cover the portion of the infrared spectrum that is completely inaccessible to ground-based observatories and which is essential for studies of astronomical sources with temperatures between tens and hundreds of degrees Kelvin. Its ability to make polarimetric measurements of aligned dust grains provides a unique new capability for studying interstellar magnetic fields. HAWC[Formula: see text] began commissioning flights in April 2016 and was accepted as a facility instrument in early 2018. In this paper, we describe the instrument, its operational procedures, and its performance on the observatory.