And even though very reliable, explosive bolts do fail, sometimes spectacularly. Just a few years ago an Indian PSLV fairing separation failed, yet released the

And even though very reliable, explosive bolts do fail, sometimes spectacularly. Just a few years ago an Indian PSLV fairing separation failed, yet released the sattelite inside the closed fairing, which did reach orbit. As it could not get out, this was a failed launch & IIRC the failed fairing separation mechanism was pyrotechnic.