space Cadet as long as he could remember. After taking the entrance exams, he had been accepted for the rigid training that would prepare him to enter the ranks of the great Solar Guard. He had met his two unit-mates, Roger and Astro, on his very first day at the Academy, and after a difficult beginning, adjusting to each other's personalities and the discipline of the Academy routine, the three boys had become steadfast friends.

As control-deck cadet and pilot, Tom was head of the unit, second-in-command to Captain Strong. And while he could issue orders to Astro and Roger and expect to be obeyed, the three cadets all spoke their minds when it came to making difficult decisions. This had solidified the three cadets into a fighting, experienced, dependable unit.

Tom made a final check on the gravity generator and turned to the intercom.

"All departments, report!" he called.

"Radar bridge checks in O.K.," replied Roger.

"Power deck checks in on the nose, Tom," reported Astro.

"Right! Stand by! We blast as soon as the skipper gets around."

Tom turned to the teleceiver and switched it on. The screen blurred and then steadied into a view of the spaceport outside. Tom scanned the launching ramp below, and, satisfied it was clear, he switched the teleceiver to the spaceport traffic-control circuit.

"Rocket cruiser Polaris to spaceport control," he called. "Come in, spaceport control. Request orbit clearance."

"Spaceport traffic control to Polaris," reported the traffic officer, his face in focus on the teleceiver screen. "Your orbit has been cleared for blast-off. Orbit number 3847—repeat, 3847—raise ship when ready!"

"Orbit 3847," repeated Tom. "End transmission!"

"End transmission," said the officer. Tom flipped off the teleceiver and the officer's face disappeared.

At the rear of the control deck, Captain Strong suddenly stepped through the hatch and dropped his black plastic space bag on the deck. Tom got up and saluted sharply.

"Polaris ready to blast off, sir," he said. "Orbit cleared."

"Very well, Corbett," replied Strong, returning the salute. "Carry on!"

Tom turned back to the control board and flipped on the intercom. "Control deck to power deck! Energize the cooling pumps!"

"Cooling pumps, aye!" said Astro.

From the power deck, the massive pumps began their whining roar. The great ship shuddered under the pressure.

Tom watched the gauge that indicated the pressure control and then called into the intercom.

"Radar bridge, do we have a clear trajectory?'

"All clear forward and up, Tom," reported Roger from the radar bridge.

"Strap in for blast-off!" bawled the curly-haired cadet.

Captain Strong took his place in the pilot's chair next to Tom and strapping himself in snapped out, "Feed reactant!"

Spinning a small wheel at the side of the control panel, Tom reported, "Feeders at D-9 rate, sir!"

Then, as the hiss of fuel pouring into the mighty engines of the ship blended with the whine of the pumps, Tom snapped out a third order. "Cut in take-off six yards!"

Receiving acknowledgment from below, he grasped the master blast-off switch and watched the sweeping hand of the astral chronometer.

"Stand by to raise ship!" he yelled. "Blast off minus—five—four—three—two—one—zero!"

He pulled the switch.

Slowly, the rockets blasting evenly, the giant ship lifted itself free of the ground. Then, gaining speed, it began rocketing away from the Earth. Like a giant shining bullet, the great spaceship blasted through the dark void of space, her nose pointed to the distant misty planet of Venus.

Once again Tom Corbett and his unit-mates had embarked on a mission for the Solar Guard.

CHAPTER 2

"Stand by for touchdown!" bellowed Captain Strong's voice on the big spaceship's intercom.

"Control deck standing by," replied Tom.

"Corbett," Strong continued, "you may take her down as soon as you get clearance from Venusport traffic control."

Tom acknowledged the order with a brisk "Aye, sir! In a few moments he received permission to touch down on the newly colonized planet. Then, turning his attention to the control board, he requested a ground-approach check from Roger.

"About two miles to touchdown, Tom," reported Roger from the radar bridge. "Trajectory clear!"

"O.K., Roger," said Tom. Glancing quickly at the air speed and rocket thrust indicators, he flipped a switch and sang out, "Power deck, reduce thrust on main drive rockets to minimum!"

"Got ya, Tom," boomed Astro.

"Closing in fast, sir," said Tom to Strong, who had come up from below and now stood at the cadet's shoulder watching as Tom maneuvered the big ship through the Venusian atmosphere, his keen eyes sweeping the great panel of recording gauges and dials.

"One thousand feet to touchdown," intoned Roger from the radar bridge.

Reacting swiftly, Tom adjusted several levers, then picking up the intercom microphone, he threw a switch and yelled, "Power deck! Full braking thrust!"

Deep inside the Polaris, Astro, who tended the mighty rocket power plant with loving care, eased home the sensitive control mechanism, applying even pressure to the braking rockets.

As the giant spaceship settled smoothly to within a few feet of the surface of the concrete spaceport, Tom threw the master switch that cut all power. A moment later the huge craft dropped easily, then settled on the landing platform with a gentle thump.

"Touchdown!" yelled Tom. Then, glancing at the astral chronometer on the control board, he turned to Strong, and saluting smartly, reported, "Polaris completes space flight at exactly seven fifty-two-O-two!"

Strong returned the salute. "Very well, Tom. Now, I want you, Roger, and Astro to come with me to the exposition commissioner's office for an interview and detailed orders."

"Yes, sir," said Tom.

A few minutes later, dressed in fresh uniforms, the three cadets followed their unit commander out of the ship, then stood by as Strong ordered the chief petty officer of an enlisted Solar Guard working party to prepare the Polaris for moving to the exposition site.

"Empty the reactant fuel tanks of all but enough for us to raise ship and touch down over to the fairgrounds," said Strong. "Better strip her of armament, too. Paralo-ray pistols and rifles, the three-inch and six-inch atomic blasters, narco sleeping gas; in fact, everything that could possibly cause any trouble."

"Yes, sir," replied the scarlet-clad enlisted spaceman.

"One thing more," added Strong. "There will be a crew living aboard, so please see that the galley is stocked with a full supply of both fresh and synthetic foods. That's about all, I guess."

"Very well, sir," replied the petty officer with a crisp salute. He turned and began bawling orders to a squad of men behind him and immediately they were swarming over the great ship like ants.

Fifteen minutes later, a jet cab swerved to a stop in front of the tallest of the Venusport buildings, the Solar Alliance Chamber. Strong paid the driver, adding a handsome tip, and flanked by his three cadets strode briskly into the building.

Crossing a high-ceilinged lobby, they entered an express vacuum elevator and five seconds later stepped out onto the four-hundredth floor. There, Strong slid a panel door to one side, and, followed by the cadets, stepped inside the office of Mike Hawks, exposition commissioner and retired senior officer of the Solar Guard.

The office was impressively large and airy, with an outside wall forming a viewport of clear Titan crystal reaching from floor to vaulted ceiling and