Page 1271 - Enders_Game_Full_Book

Here, too. He could have gone back to the barracks and napped. Instead, he risked getting in trouble just to find out things that no doubt he would have learned in the ordinary course of events.
Why did I come up here? What was I looking for?
The key. The world was full of locked doors, and he had to get his hands on every key.
He stood still and listened. The room was nearly silent. But there was white noise, background rumble and hiss that made it so sounds didn't carry throughout the entire station.
With his eyes closed, he located the source of the faint rushing sound. Eyes open, he then walked to where the vent was. An out-flowing vent with slightly warmer air making a very slight breeze. The rushing sound was not the hiss of air here at the vent, but rather a much louder, more distant sound of the machinery that pumped air throughout the Battle School.
Sister Carlotta had told him that in space, there was no air, so wherever people lived, they had to keep their ships and stations closed tight, holding in every bit of air. And they also had to keep changing the air, because the oxygen, she said, got used up and had to be replenished. That's what this air system was about. It must go everywhere through the ship.
Bean sat before the vent screen, feeling around the edges. There were no visible screws or nails holding it on. He got his fingernails under the rim and carefully slid his fingers around it, prying it out a little, then a little more. His fingers now fit under the edges. He pulled straight forward. The vent came free, and Bean toppled over backward.
Only for a moment. He set aside the screen and tried to see into the vent. The vent duct was only about fifteen centimeters deep from front to back. The top was solid, but the bottom was open, leading down into the duct system.
Bean sized up the vent opening just the way he had, years before, stood on the seat of a toilet and studied the inside of the toilet tank, deciding whether he could fit in it. And the conclusion was the same -- it would be cramped, it would be painful, but he could do it.
He reached an arm inside and down. He couldn't feel the bottom. But with arms as short as his, that didn't mean much. There was no way to tell by looking which way the duct went when it got down to the floor level. Bean could imagine a duct leading under the floor, but that felt wrong to him. Sister Carlotta had said that every scrap of material used to build the station had to be hauled up from Earth or the manufacturing plants on the moon. They wouldn't have big gaps between the decks and the ceilings below because that would be wasted space into which precious air would have to be pumped without anyone breathing it. No, the ductwork would be in the outside walls. It was probably no more than fifteen centimeters deep anywhere.
He closed his eyes and imagined an air system. Machinery making a warm wind blow through the narrow ducts, flowing into every room, carrying fresh breathable air everywhere.