He had not seen it before, that patrol ship, clinging like a leech to the airlock of the crystal hemisphere. There had been men in there when the air escaped. They had been saved from death by the closing of their automatic airlocks.
"Better get back into the shelter of The Bubble," he told Jan after a hurried trip to the astrogator's cabin. The spider man turned the vessel, and they scurried back to shelter. Although the patrol ship tried its gravity buttons on them, the Mugs had fully equipped their own vessel with similar, and larger buttons which were occasionally used in regulating the metal satellite's orbit. They could neutralize the other vessel's gravity force with ease.
"And yet," Sine admitted to the serious little group in the cabin, as they once more floated in space under the immense sphere, "they seem to have us stymied."
"Suppose they follow us around here?" Kass asked somewhat nervously.
"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?"