When Dr. Smith accidentally blows out a power relay, the Jupiter 2 is left with insufficient energy to meet its needs. One consequence is that the Robot cannot be recharged; Will is particularly upset because, when the Robot’s power reserves are completely used up, it will cease to function—effectively, the Robot will die. In an attempt to save Will and the other Robinsons from further pain, the Robot records a message to them before leaving camp to go off and die. He travels as far as he can before his energy is so low that he collapses in the Valley of Shadows.