colonists on Venus, the misty planet, his formal education was limited, and though he had no equal while on the power deck of a rocket ship, in theory and classroom study he had to depend on Roger and Tom to help him get passing grades.

The slidewalk moved smoothly and easily toward the gleaming Tower of Galileo, the largest and most imposing of the structures of Space Academy. Made entirely of clear crystal mined on Titan, satellite of Saturn, the Tower rose over the smaller buildings like a giant shimmering jewel. Housing the administration offices of the Solar Guard and the Space Academy staff, it also contained Galaxy Hall, the museum of space, which attracted thousands of visitors from every part of the Solar Alliance.

Tom Corbett, his eyes caressing the magnificent gleaming Tower, remembered the first time he had seen it. While it hadn't been so long in months or years since becoming a Space Cadet, it seemed as though he had been at the Academy all of his life and that it was his home. In the struggle to develop into a well-knit dependable rocket team, composed of an astrogator, power-deck cadet, and a command cadet, Tom had assumed the leadership of the unit, and the relationship between Astro, Roger Manning, and himself had ripened until they were more like brothers than three young men who had grown up millions of miles apart.

As they rode toward the Tower, the three cadets could see the green-clad first-year Earthworms getting their first taste of cadet life--hours of close-order formations and drills. The nearer they came to the Tower, the more intense and colorful became the activity as the crisscrossing slidewalks carried enlisted guardsmen in their red uniforms, and the officers of the Solar Guard in magnificent black and gold, across the quadrangle to the various dormitories, laboratories, lecture rooms, mess halls, and research rooms. Space Academy was a beehive of activity, with the education of thousands of cadets and the operational mechanics of the Solar Guard going on incessantly, day and night, never stopping in its avowed task of defending the liberties of the planets, safeguarding the freedom of space, and upholding the cause of peace throughout the universe.

As their slidewalk glided over the quadrangle, Roger suddenly turned to his unit mates. "Think we might get assigned to that radar project they're setting up on the Moon?" he asked. "I have a few ideas—"

Tom laughed. "He can't wait until he gets his hands on that new scanner Dr. Dale just finished, Astro," he said with a wink.

The big Venusian snorted. "Can you imagine the ego of that guy? Dr. Dale spends almost a year building that thing, with the help of the leading electronic scientists in the Alliance, and he can't wait to tell them about a few of his ideas!"

"I didn't mean that," complained Roger. "All I said was—"

"You don't have to say a word, hot-shot," interrupted Astro. "I can read your thoughts as though they were flashed on a stereo screen!"

"Oh, yeah!" growled Roger. "You should be that telepathic for your exams. Why didn't you read my thoughts when I beat my brains out trying to explain that thrust problem the other night?" He turned to Tom, shrugging his shoulders in mock despair. "Honestly, Tom, if I didn't know that he was the best power jockey in the Academy, I'd say he was the dumbest thing to leave Venus, including the dinosaurs in the Academy Zoo!"

With a hamlike hand Astro suddenly grabbed for Roger's neck, but the wiry cadet dashed along the slidewalk out of reach and the big Venusian rumbled after him. Tom roared with laughter.

As he started to follow his unit mates, one of the passengers on the slidewalk grabbed Tom by the arm and he turned to see Mike McKenny, Chief Warrant Officer in the enlisted Solar Guard and the first instructor the Polaris unit had met on their arrival at the Academy.

"Corbett!" demanded McKenny. "Are those two space crawlers still acting like monkeys out of their cages?"

Tom laughed and shook hands with the elderly spaceman. "Yes, sir," he said. "But you could hardly call Astro a monkey!"

"More along the lines of a Venusian gorilla, if you ask me!" snorted McKenny. The short, squat spaceman's eyes twinkled. "I've been hearing some mighty fine things about you three space bongos, Tommy. It's a wonder the Solar Guard didn't give you a unit citation for aiding in the capture of Coxine, the pirate!"

"Thanks, Mike. Coming from you that compliment really means something!"

"Just be sure you keep those two space lunatics in their proper cages," said Mike, indicating Roger and Astro, who at the moment were racing back and forth along the slidewalk bumping passengers left and right, "and you'll all be heroes someday."

"Yes, sir," said Tom. He glanced up, and noticing that he was in front of the Tower building, hopped to the walkway, waving a cheery good-by to Mike. "Blast over to our mess and have dinner with us some night, Mike!" he yelled to the departing figure.

"And interrupt the happiest hours in Astro's life?" bawled Mike. "No thank you!"

Tom laughed and turned to the huge open doorway of the Tower where Roger and Astro waited for him impatiently. In a few moments the three were being carried to the upper floors of the crystal structure by a spiraling band of moving plastic that stretched from the top of the Tower to the many floors below surface level. Tom glanced at his wrist chronograph as they stepped off the slidestairs and headed for Captain Strong's quarters.

"We're about twenty minutes late," he said to Roger and Astro. "Hope Captain Strong's in good spirits!"

"If he isn't," said Roger, "we can—"

"Don't say it," protested Astro. "I only just finished working off my last bunch of galley demerits."

They stopped in front of a door, straightened their uniforms, and then slid the door to one side and stepped smartly into the room. They came to rigid attention before a massive desk, flanked by two wall windows of clear sheet crystal reaching from ceiling to floor. Standing at the window, Captain Steve Strong, Polaris unit cadet supervisor, his broad shoulders stretching under his black-and-gold uniform, turned to face them, his features set in grim lines of trouble.

"Polaris unit reporting for orders, sir," said Tom. The three cadets saluted crisply.

Strong snapped a return salute and walked to the front of his desk. "Getting pretty big for your britches, aren't you?" he growled. "I've been watching you from this window. I saw the messenger deliver my orders to you, and then, I saw you return to your game and finish it, apparently deciding that the business of the Solar Guard can wait!"

"But, sir—" Roger started to say.

"Close your exhaust, Manning!" snapped Strong. "I'm doing the talking!"

"Yes, sir," stammered the blond-haired cadet.

"Well, Cadets," asked Strong in a silken voice, "if I sent you to Commander Walters' office on the double, do you think I could trust you to get there on the double?"

"Oh, yes, sir," replied Tom. "Yes, sir!" The other two boys nodded violently.

"Then blast out of here and report to Commander Walters for your assignments. Tell him I'll be there in a few minutes."

"Yes, sir!" said Tom, and the three cadets saluted sharply.

"Unit—" bawled Strong, "dis—missed!"

Outside in the hall once more, the three cadets wiped their faces.

"Captain Strong definitely was not in a good mood!" commented Roger.

"I've never seen him so angry!" said Tom. "Wonder why."

"Think it might be something to do with our assignments?" asked Astro.

"Never can tell,