"Okay, Jack--let 'er rip!" They were able to watch the operation on a screen, from sensors left on site. The fuel-cell-powered ripper hummed, and there was a sudden screeching noise audible all the way down the corridor as the lever arms inserted themselves forcibly into the narrow crack between the door valves. The humming abruptly dropped in pitch and became louder as it began to force the doors open. A.J."