 The characters experience many emotions for the first time during the events of this story.  What emotion(s) push the characters through the door.
When nobody aboard ship remembers where it's going, how can they tell when it has arrived? But ever since the engines somewhere in the rear of the world had changed their tone, from the steady whining Rikud had heard all twenty-five years of his life, to the sullen roar that came to his ears now, the feelings had grown. Instead, there was more of the blackness, and one very bright star set apart by itself in the middle of the viewport. But it came again, and each time it left him with a feeling he could not explain. Rikud knew that something which he could not explain had entered the elder man's head for a moment, but it had departed almost before Chuls knew of its existence. There was a strange thought, and Rikud's brain whirled once more down the tortuous course of half-formed questions and unsatisfactory answers. Once, here in this same ray room, he had had the impulse to hurl himself head-first against the wall, just to see what would happen. But something soft had cushioned the impact—something which had come into being just for the moment and then abruptly passed into non-being again, something which was as impalpable as air. Rikud had been stopped in this action, although there was no real authority to stop him. They told you to do something and you did it, but that was silly, because now no one told you to do anything. There had been a revolt—again a term without any real meaning, a term that could have no reality outside of the reading machine—and the elders were overthrown. The people had decided that they did not know where they were going, or why, and that it was unfair that the elders alone had this authority. They were born and they lived and they died as the elders directed, like little cogs in a great machine. Much of this Rikud could not understand, but he knew enough to realize that the reading machine had sided with the people against the elders, and it said the people had won. Rikud often thought of his own death, still seventy-five years in the future, not without a sense of alarm. True, this was the only case of its kind, the exception to the rule, but it proved the world was not perfect. "Yes?" Almost no one read any more, and the library was heavy with the smell of dust. You can find several of them under 'astronomy,' with a cross-reference under 'stars.'
 Hatred and anger.
 Sadness  Hatred and anger.  Excitement and curiosity.  Pure happiness.