 How was Dr. Mansard's radio and ship drive destroyed?
Trella feared she was in for trouble even before Motwick's head dropped forward on his arms in a drunken stupor. Perhaps she could call one of Motwick's friends; she had no one on Ganymede she could call a real friend herself. It smashed on Kregg's head, splashing the floor with liquor, and Kregg sank stunned to his knees. The gravity of Ganymede was hardly more than that of Earth's moon, but the way the man picked up the limp Motwick with one hand and tossed him over a shoulder was startling: as though he lifted a feather pillow. I was born and brought up there, and I was finally able to build a small rocket with a powerful enough drive to clear the planet.” “If Dr. Mansard succeeded in landing on Jupiter, why didn't anyone ever hear from him again?” she demanded. Trella had the desk clerk call a cab to deliver the unconscious Motwick to his home. For some reason she decided against telling him that the assignment on which she had come to the Jupiter system was to gather his own father's notebooks and take them back to Earth. Motwick was an irresponsible playboy whom Trella had known briefly on Earth, and Trella was glad to dispense with his company for the remaining three weeks before the spaceship blasted off. The ship that they boarded on Moon Nine was one of the newer ships that could attain a hundred-mile-per-second velocity and take a hyperbolic path to Earth, but it would still require fifty-four days to make the trip. The Cometfire swung around great Jupiter in an opening arc and plummeted ever more swiftly toward the tight circles of the inner planets. She told him only that she was a messenger, sent out to Ganymede to pick up some important papers and take them back to Earth. Her employer had impressed upon her that her mission was confidential, but surely Dom Blessing could not object to Dr. Mansard's son knowing about it. All these things had happened before she was born, and she did not know what Dom Blessing's relation to Dr. Mansard had been, but it must have been very close. Dr. Mansard and his wife had disappeared into the turbulent atmosphere of Jupiter just after his invention of the surgiscope, and it had been developed by Dom Blessing. Through all these years since Dr. Mansard's disappearance, 55 Blessing had been searching the Jovian moons for a second, hidden laboratory of Dr. Mansard. When it was found at last, he sent Trella, his most trusted secretary, to Ganymede to bring back to him the notebooks found there.
 Blessing intentionally ruined it in the hopes that Mansard would die
 Dr. Mansard destroyed it himself to eliminate any record of his survival  It was never destroyed  Blessing intentionally ruined it in the hopes that Mansard would die  It could not withstand the harsh elements of Jupiter's atmosphere