It stopped and they trotted across the drawbridge into the ship. Inside the airlock stood a space-marines sergeant, gaudy and splendid who kept repeating, "Seventh deck! Down the hatch to your own deck-step lively!" He pointed to the hatch, down which disappeared a narrow, vertical steel ladder.
Matt hitched his jump bag out of his way and lowered himself into the hatch, moving fast to avoid getting his fingers stepped on by the cadet who followed him. He lost track of the decks, but there was a sergeant master-at- arms on each. He got off when he heard, "Third deck!"
He was in a wide, low cylindrical compartment, the deck of which was covered with plastic-foam padding. It ,was marked off in sections, each about seven feet by three and fitted with safety belts.
Matt found an unoccupied section, sat down, and waited. Presently cadets stopped dribbling in, the room was crowded. The master-at-arms called out, "Down, everybody-one to a section." He then counted them by noting that all sections were filled.
A loudspeaker warned, "All hands, prepare for acceleration!" The sergeant told them to strap down and remained standing until all had done so. He then lay down, grasped two handholds, and reported the third deck ready.
"All hands, stand by to raise!" called out the speaker.
There was a long and breathless wait.
"Up ship!" shouted the speaker.
Matt felt himself pressed into the padding.
Terra Space Station and the school ship Randolph He in a circular orbit 22,300 miles above the surface of the Earth, where they circle the Earth in exactly twenty-four hours, the natural period of a body at that distance.
Since the Earth's rotation exactly matches their period, they face always one side of the Earth-the ninetieth western meridian, to be exact. Their orbit lies in the ecliptic, the plane of the Earth's orbit around the Sun, rather than in the plane of the Earth's equator. This results in them swinging north and south each day as seen from the earth. When it is noon in the Middle West, Terra Station and the Ran-
dolph lie over the Gulf of Mexico; at midnight they lie over the South Pacific.
The state of Colorado moves eastward about 830 miles per hour. Terra Station and the Randolph also move eastward nearly 7000 miles per hour- 1.93 miles per second, to be finicky. The pilot of the Bolivar had to arrive at the Randolph precisely matched in course and speed. To do this he must break his ship away from our heavy planet, throw her into an elliptical orbit just tangent to the circular orbit of the Randolph and with that tangency so exactly placed that, when he matched speeds, the two ships would lie relatively motionless although plunging ahead at two miles per second. This last maneuver was no easy matter like jockeying a copter over a landing platform, as the two speeds, unadjusted, would differ by 3000 miles an hour.
Getting the Bolivar from Colorado to the Randolph, and all other problems of journeying between the planets, are subject to precise and elegant mathematical solution under four laws formulated by the saintly, absent- minded Sir Isaac Newton nearly four centuries earlier than this flight of the Bolivar-the three Laws of Motion and the Law of Gravitation. These laws are simple; their application in space to get from where you are to where you want to be, at the correct time with the correct course and speed, is a nightmare of complicated, fussy computation.
The "weight" pressing Matt into the padding was four gravities-Matt weighed nearly six hundred pounds. He lay there, breathing with difficulty, while the ship punched its way through the thick soup of air and out into free space. The heavy weight bound down the cadets while the Bolivar attained a speed of some six miles per second and climbed to an altitude of 900 miles.
At the end of five minutes and a few odd seconds the drive stopped.
Matt raised his head, while the sudden silence rang in his ears. The master-at-arms detected Mart's movement and others. He shouted, "Stay where you are-don't move."
Matt relaxed. They were in free fall, weightless, even though the Bolivar was speeding away from the Earth at more than 20,000 miles an hour. Each body-ship, planet, meteor, atom-in space falls continually. It moves also with whatever other motion it has inherited from its past experience.
Matt was acutely aware of his weightlessness, for his stomach told him about it, complainingly. To be on the safe side, he removed a sick kit from his jump bag, but he did not put it on. He was feeling queasy; it was not as bad as it had been on his test flight, not half as bad as the "bumps." He hoped to get by without losing his breakfast.
The loudspeaker sang out, "End of acceleration. Four hours of free fall." The master-at-arms sat up. "You can unstrap now," he said.
In a matter of seconds the compartment took on the look of a particularly crowded aquarium. One hundred boys were floating, swimming, squirming in every attitude and position between the deck and the overhead. These two barriers no longer seemed like floor and ceiling since up-and-down was gone; they were simply walls which rotated slowly and erratically for each observer as his own body turned past them.
"Hey, you guys!" yelled the sergeant. "Grab on to something and listen to me." Matt looked around, found himself near the overhead, spotted a handhold, and grasped it. "It's time you kids learned some traffic rules for free flight. You got to learn to zig when the other guy zags. If you happen to meet the Captain and you zig when you should 'a' zagged and bump him, he ain't going to like it. See?"
He stuck out a scarred thumb. "Rule one: all groundhogs -that's you and don't try to tell me anything different-are required to hold on with at least one hand at all times. That applies until you pass your free-fall acrobatics test. Rule two.- give way to officers and don't make them have to shout 'Gangway!' Besides that, give way to anybody on duty, or busy, or with his hands full.
"If you're moving aft, pass inboard of the man you meet, and contrariwise if you're moving forward. If you're moving clockwise, figuring 'clockwise' from the bow end of the ship, you pass the man you meet outboard and let him pass inboard- contrariwise for counterclockwise. No matter what direction you're going, if you overtake a man you pass inboard of him. Is that all clear?"
Matt thought it was, though he doubted if he could remember it. But a remaining possibility occurred to him. "Sergeant," he asked innocently, "suppose you're moving directly in or out from the center of the ship-what do you do?"
The sergeant looked disgusted, which gave his face an odd appearance to Matt, as their two faces were upside down with respect to each other. "You get what usually happens to jaywalkers-okay, so you're moving across the traffic: just stay out of everybody's way. It's your lookout. Any more questions?"
No one answered; he went on: "All right, go out and look around the ship- but try to behave yourselves and not bump into anybody so you'll be a credit to deck three."
The third deck had no ports of any sort, but the Bolivar was a long-jump transport; she possessed recreation rooms and viewports. Matt started forward, seeking a place from which to get a glimpse of the Earth.
He remembered to pass outboard as he pulled himself along, but apparently some passengers had not been indoctrinated. Each hatchway was a traffic jam of youngsters, each trying to leave his own deck to sight-see in some other deck, any deck.
The sixth deck, he found, was a recreation room. It contained the ship's library-locked-and games equipment, also locked. But it did have six large viewports.
The recreation deck had carried a full load of passengers. Now, in free fall, cadets from all other decks gradually ' found their way to the recreation deck, just as Matt had, seeking a view of outside; at the same time the original roster of that deck showed no tendency to want to leave their favored billet.
It was crowded.
Crowded as a basket full of kittens-Matt removed someone's space boot from his left eye and tried to worm his way toward one of the ports. Judicious work with his knees and elbows and a total disregard of the rules of the road got him to the second or third layer near one port. He placed a hand on a shoulder in front of him. The cadet twisted around. "Hey! Who do you think you're shoving? Oh-hello, Matt."