in any case there was no alternative.
Battery condition was, perhaps, the item that concerned him most. The nearest charging point was two thousand kilometers higher, and if they couldn’t climb back to that they would be in trouble. But he was quite happy on this score; during the braking process, the transporter’s drive motors had been functioning as dynamos, and ninety percent of its gravitational energy had been pumped back into the batteries. Now that they were fully charged, the surplus hundreds of kilowatts still being generated should be diverted into space through the big cooling fins at the rear.
Those fins, as Chang’s colleagues had often pointed out to him, made his unique vehicle look rather like an old-time aerial bomb. By this time, at the end of the braking process, they should have been glowing a dull red. Chang would have been very worried had he known that they were still comfortably cool. Energy can never be destroyed; it has to go somewhere. And often it goes to the wrong place.
When the FIRE—BATTERY COMPARTMENT sign came on for the third time, Chang did not hesitate to reset it. A real fire, he knew, would have triggered the extinguishers. In fact, one of his biggest worries was that these might operate unnecessarily.
There were several anomalies on the board now, especially in the battery-charging circuits. As soon as the journey was over and he’d powered down the transporter, Chang was going to climb into the motor room and give everything a good old-fashioned eyeball inspection.
As it happened, his nose alerted him first, when there was barely more than a kilometer to go. Even as he stared incredulously at the thin wisp of smoke oozing out of the control board, the coldly analytical part of his mind was saying, “What a lucky coincidence that it waited until the end of the trip!”
Then he remembered all the energy being produced during the final braking, and had a pretty shrewd guess at the sequence of events. The protective circuits must have failed to operate, and the batteries had been overcharging. One fail-safe after another had let them down. Helped by the ionospheric storm, the sheer perversity of inanimate things struck again.
Chang punched the battery-compartment fire-extinguisher button. At least that worked, because he could hear the muffled roar of the nitrogen blasts on the other side of the bulkhead. Ten seconds later, he triggered the VACUUM DUMP, which would sweep the gas out into space, with, he hoped, most of the heat it had picked up from the fire. That, too, operated correctly. It was the first time that Chang had ever listened with relief to the unmistakable shriek of atmosphere escaping from a space vehicle; he hoped it would also be the last.
He dared not rely on the automatic-braking sequence as the vehicle finally crawled into the terminus. Fortunately, he had been well rehearsed and recognized all the visual signals, so that he was able to stop within a centimeter of the docking adapter. In frantic haste, the air locks were coupled together, and stores and equipment were hurled through the connecting tube.
And so was Professor Sessui, by the combined exertions of pilot, assistant engineer, and steward, when he tried to go back for his precious instruments. The air-lock doors were slammed shut just seconds before the engine compartment bulkhead finally gave way.
After that, the refugees could do nothing but wait in the bleak fifteen-meter-square chamber, with considerably fewer amenities than a well-furnished prison cell, and hope that the fire would burn itself out. Perhaps it was as well for the passengers’ peace of mind that only Chang and his engineer appreciated one vital statistic: the fully charged batteries contained the energy of a large chemical bomb, now ticking away on the outside of the Tower.
Ten minutes after their hasty arrival, the bomb went off, causing slight vibrations of the Tower, followed by the sound of ripping and tearing metal. Though the breaking-up noises were not impressive, they chilled the hearts of the listeners. Their only means of transport was being destroyed, leaving them stranded twenty-five thousand kilometers from safety.
There was another, more protracted, explosion—then silence. The refugees guessed that the vehicle had fallen off the face of the Tower. Numbed, they started to survey their resources; and slowly they began to realize that their miraculous escape might have been wholly in vain.
44. A Cave in the Sky
Deep inside the mountain, amid the display and communications equipment of the Earth Operations Center, Morgan and