"I don't think they can," Sine said. "I noticed when we came to The Bubble first, the ships are locked to the gaskets from inside the sphere. The men inside the ship can not unlock their ship unless they open the emergency air curtain. If they did their air would all escape through the sphere. They could do it, of course, if they put on space suits. But that procedure would take an hour, and in the mean time we could get out of range of their heat rays. So we have them stymied too. Except for one thing----" "Of course," Lents grunted. "We can't get at them, and they can't get at us, but in a few hours we'll be in sunlight again, and some patrol will pick us up." The Mugs, watching fearfully from beyond the doorway, turned aside. Were they, after a mere glimpse of freedom, to be immediately returned to the bondage which had become unbearable to them? Sine felt a small, thin hand slip into his. He looked down into the wistful face of Proserpina looking up at him with hope, with confidence. All at once his shyness vanished as he realized that Proserpina's obvious adoration for him was only the admiration of a child for a very big and very wonderful brother. At the same time his desire to do something to release them all from their peril was intensified by the imperatively felt need to justify her confidence in him. An idea came. "Jan," he asked. "What is the energy output--the total capacity--of our gravity buttons?" Jan named an approximate figure in ergs. "Lents, if you've ever calculated to a purpose, calculate now! How much energy is represented by the mass of that sphere at its orbital velocity?" "I get you!" The fat scientist puffed out his cheeks with excitement. "Have to estimate the mass first." He picked up a stylus from the astrogator's table, worked furiously on a tablet. Kass and Jan watched apprehensively. The Pleasure Bubble, with its freight of the dead, was hurrying remorselessly to its rendezvous with the sunlight. "Whoops!" Lents threw his tablet into the air in extravagant triumph. "She'll do!" "Stations!" shouted Jan, in his curious strained voice, and men rushed eagerly to their posts, still hazy as to their object but cheered by the knowledge that there was hope after all. Then began one of the strangest duels in the history of the solar system. Setting the nose of their vessel against the gigantic metal satellite, they directed the stern gravity buttons against a distant star, and applied full force to slow the sphere in its orbit. The forces liberated were terrific. The sphere's tough skin, three inches thick, buckled and bent inward until the ship was almost buried in a pit of its own creation. Jan stood hunched over the activator lever like a great spider, ready to throw it into neutral at the first sign of an actual rupture, which would send them crashing through the internal cells and girders of the sphere.