This half of a hold-down post frangible nut was recovered on April 24, 1990, after it secured one of the Solid Rocket Boosters (SRB) launching the Hubble Space Telescope on space shuttle Discovery. Each booster had four hold-down posts that secured it and the mobile launch platform's posts together. Each bolt had a nut at each end but only the top nut was frangible. It had two detonators, which were ignited at solid rocket motor ignition. When the detonators went off, the nut halves were caught in a blast container.