During the party, the ship's planetographer drunkenly complains to the captain that an electrical apparatus he was working on blew out when they were trying to lift the sphere. This leads to a moment of drunken clarity for the captain: the sphere, he realizes, is actually a power broadcaster. It absorbs energy of all sorts, including potential energy (which is why it can't be lifted), then converts it with near total efficiency to electromagnetic radiation, broadcasting at a frequency of 30,000 hertz, which happens to be the frequency the planetographer's apparatus was set to receive.