The giant ship began to shudder as the mighty pumps on the power deck started their build.
Tom strapped himself into the pilot's seat and began checking the dials in front of him. Satisfied, he fastened his eyes on the sweep hand of the time clock. Above his head, the teleceiver screen brought him a clear picture of the Academy spaceport. He watched the giant cruisers take to the air one by one and rocket into the vastness of space.
The clock hand reached the ten-second mark.
"Stand by to raise ship!" Tom called into the intercom. The red hand moved steadily, inexorably. Tom reached for the master switch.
"Blast off minus--five--four--three--two--one--_zero_!"
Tom threw the switch.
The great ship hovered above the ground for a few moments. Then it heaved itself skyward, faster and ever faster, pushing the Earthmen deep into their acceleration cushions.
Reaching free-fall space, Tom flipped on the artificial-gravity generator. He felt its pull on his body, quickly checked all the instruments and turned to Captain Strong.
"Ship space-borne at six hundred fifty-three, sir."
"Very well, Corbett," replied Strong. "Check in with the _Arcturus_, _Capella_ and the _Centauri_, form up on one another and assume a course that will bring you back over Academy spaceport at eight hundred hours, when we will open orders."
"Yes, sir," said Tom, turning back eagerly to the control board.
For nearly two hours the four rocket ships of Squadron A moved through space in a perfect arc, shaping up for the 0800 deadline. Strong made use of the time to check a new astrogation prism perfected by Dr. Dale for use at hyperspace speeds. Tom rechecked his instruments, then prepared hot tea and sandwiches in the galley for his shipmates.
"This is what I call service," said Astro. He stood stripped to the waist, a wide leather belt studded with assorted wrenches of various shapes and sizes strapped around his hips. In one hand he carried a wad of waste cotton with which he continually polished the surfaces of the atomic motors, while his eyes constantly searched the many gauges in front of him for the slightest sign of engine failure.
"Never mind bringing anything up to Manning. I'll eat his share."
Astro had deliberately turned the intercom on so Roger on the radar deck might hear. The response from that corner was immediate and emphatic.
"Listen, you rocket-headed grease monkey," yelled Roger. "If you so much as smell that grub, I'll come down and feed you into the reactant chamber!"
Tom smiled at Astro and turned to the ladder leading up from the power deck. Passing through the control deck on the way to the radar bridge, he glanced at the clock. It was ten minutes to eight.
"Only one thing I'm worried about, Corbett," said Roger through a mouthful of sandwich.
"What's that?" asked Tom.
"Collision!" said Roger. "Some of these space-happy cadets might get excited, and I for one don't want to wind up as a flash in Earth's atmosphere!"
"Why, you have radar, to see anything that goes on."
"Oh, sure," said Roger, "I can keep this wagon outa their way, but will they stay outa mine? Why my father told me once--" Roger choked on his food and turned away to the radar screen.
"Well," said Tom after a moment, "what _did_ your father tell you?"
"Ah--nothing--not important. But I've got to get a cross-fix on Regulus before we start our little games."
Tom looked puzzled. Here was another of Roger's quick changes of attitude. What was it all about? But there was work to do, so Tom shrugged his shoulders and returned to the control deck. He couldn't forget what Roger had said about a collision, though.
"Excuse me, Captain," said Tom, "but have there been any serious collisions in space between ships?"
"Sure have, Tom," replied Strong. "About twenty years ago, maybe less, there was a whole wave of them. That was before we developed superrebound pulse radar. The ships were faster than the radar at close range."
Strong paused. "Why do you ask?"
Before Tom could answer, there was a sharp warning from the captain.
"Eight o'clock, Corbett!"
Tom ripped open the envelope containing the sealed orders.
"Congratulations," he read. "You are in command of the defenders. You have under your command, Squadrons A--B--C--D--E--F. Squadrons G and H are your enemies, and at this moment are on their way to attack Luna City. It is your job to protect it and destroy the enemy fleet.
Spaceman's luck! Walters, Commander Space Academy, Senior Officer Solar Guard."
"Roger," yelled Tom, "we've been selected as flagship for the defenders!
Get me a course to Luna City!"
"Good for us, spaceboy. I'll give you that course in a jiffy!"
" ... _Capella_ to _Polaris_--am standing by for your orders...." Tony Richards' voice crackled over the teleceiver. One by one the twenty-three ships that made up the defender's fleet checked in for orders.
"Astro," shouted Tom, "stand by for maneuver--and be prepared to give me every ounce of thrust you can get!"
"Ready, willing and able, Tom," replied Astro. "Just be sure those other space jockeys can keep up with me, that's all!"
Tom turned to Captain Strong.
"What do you think of approaching--"
Strong cut him off. "Corbett, you are in complete command. Take over--you're losing time talking to me!"
"Yes, sir!" said Tom. He turned back to the control board, his face flushed with excitement. Twenty-four ships to maneuver and the responsibility all his own. Via a chart projected on a screen, he studied various approaches to the Moon and Luna City. What would he do if he were in command of the invading fleet? He noticed the Moon was nearing a point where it would be in eclipse on Luna City itself. He studied the chart further, made several notations and turned to the teleceiver.
"Attention--attention--flagship _Polaris_ to Squadrons B and C--proceed to chart seven--sectors eight and nine. You will patrol those sectors.
Attention Squadrons D and F--proceed to Luna City at emergency space speed, hover at one hundred thousand feet above Luna City spaceport and wait for further orders. Attention, ships three and four of Squadron F--you will proceed to chart six--sectors sixty-eight through seventy-five. Cut all rockets and remain there until further orders.
The remainder of Squadron F--ships one and two--will join Squadron A.
Squadron A will stand by for further orders." Tom glanced at the clock and punched the intercom button.
[Illustration: _"Attention Squadrons D and F--proceed to Luna City"_]
"Have you got that course, Roger?"
"Three degrees on the starboard rockets, seventy-eight degrees on the up-plane of the ecliptic will put you at the corner of Luna Drive and Moonset Land in the heart of Luna City, spaceboy!" answered Roger.
"Get that, Astro?" asked Tom on the intercom.
"All set," replied Astro.
"Attention all ships in Squadron A--this is flagship--code name Starlight--am changing course. Stand by to form up on me!"