 Why is Trella being attacked?
He was a living weapon of destruction— immeasurably powerful, utterly invulnerable. Trella feared she was in for trouble even before Motwick's head dropped forward on his arms in a drunken stupor. Trella had not wanted to come to the Golden Satellite. It was a squalid saloon in the rougher section of Jupiter's View, the terrestrial dome-colony on Ganymede. A woman could not possibly make her way through these streets alone to the better section of town, especially one clad in a silvery evening dress. Perhaps she could call one of Motwick's friends; she had no one on Ganymede she could call a real friend herself. Trella swung with her whole body, and slapped him so hard he nearly fell from his chair. Her protector was obviously unwilling, but the dark man, faced with his massiveness, took no chances. The dark man moved in on Trella again as Kregg overtook his quarry and swung a huge fist like a sledgehammer. Exactly what happened, Trella wasn't sure. The dark man, who had grabbed Trella's arm, released her and ran for the door. Trella ran to the unconscious Motwick's side. He followed Trella out the door of the Golden Satellite and fell in step beside her. The transparent dome of Jupiter's View was faintly visible in the reflected night lights of the colonial city, but the lights were overwhelmed by the giant, vari-colored disc of Jupiter itself, riding high in the sky. “He and my mother lived on Jupiter until the oxygen equipment wore out at last. 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. It was peculiarly inappropriate, but not unbelievable, that the strongest and most agile man on Ganymede should be a coward. Trella could get a cab from here, but the Stellar Hotel wasn't far. 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 author does not give a clear reason for the attackers' motivations
 The author does not give a clear reason for the attackers' motivations  The attackers wish to steal Trella's documents  The attackers wish to violate Trella  The attackers are sent from Dr. Blessing to test Trella's loyalty