Tom saw three pretty girls board the ship

The blond cadet's eyes were wide with mock surprise.

"Girls? Well, what do you know about that? I never noticed!"

"Yeah, I'll bet you didn't!" said Tom.

"Well, they are trim little space dolls. And there are three of them!"

"Come on, Astro," sighed Tom. "We have to give the little boy his fun."

They walked toward the stand where Simms was still making his pitch to the crowd.

"Just five more seats left, ladies and gentlemen, only five chances to blast into space ..."

Tom stepped up and put three credits on the counter. "Three, please," he said.

Simms looked down and suddenly stopped his harangue. His eyes narrowed with suspicion as he saw the three cadets standing before him. Hesitating, he glanced around, seemingly looking for help. Then, shrugging his shoulders, he handed over the tickets and turned to the crowd. "Three tickets for the Space Cadets, who live out there in space. Just can't stay away from it, eh, boys?"

"I only hope that tub of yours holds together," said Tom.

Simms snarled out of the side of his mouth, "Shut up, wise guy!" And then continued aloud, "Yes, Space Cadet, I agree with you. Everyone should take a trip into space."

Tom started to protest, but then shrugged his shoulders and followed Roger and Astro into the ship. On the stand, Simms continued his appeal to the crowd.

"Just two more tickets left, ladies and gentlemen! Who'll be the lucky two?"

Suddenly Gus Wallace appeared from behind the ship and approached the stand, calling, "Hey, Simms!"

Simms stopped speaking and turned to his partner. "Yeah?"

"Everything's all set. Let's blast off!"

"I'll be with you as soon as I sell the last two tickets," said Simms. "Here you are, ladies and gents, the last two—"

Wallace grabbed him by the arm and yanked him from the stand. "I said we blast off, you idiot! You want to risk everything for two lousy credits?"

"O.K., O.K. Don't blow a fuse!"

Simms quickly closed the stand, turned out the lighted sign, and followed Wallace into the old freighter. He then collected the tickets and made sure all the passengers were strapped into their acceleration chairs and finally went below to the power deck. Wallace disappeared into the control room and seconds later his voice was heard over the ship's intercom gruffly announcing the blast-off. The lights in the cabin dimmed, the air was filled with a low whining hiss, and for an instant the old ship bucked and groaned. Suddenly, with a loud explosive roar, she blasted into the sky and began a sluggish arching climb into space.

"All right, fellas," said Roger, after the force of acceleration eased off, "let's try a little encircling maneuver on those girls up ahead."

"Oh, no, Roger," answered Tom. "You're flying solo on that project!"

"Yeah, you go ahead, Romeo." Astro laughed. "I'd like to see the Manning technique in action."

A loud explosion suddenly rocked the spaceship.

"What was that?" cried Roger. "Maybe this old tub won't make it after all!"

Astro smiled. "This is a chemical burner, remember? Her initial acceleration isn't enough. They have to keep blasting her to make speed."

"Oh, sure," drawled Roger, relaxing again and watching the girls ahead. "Well, here I go!" He got up and lurched down the aisle running between the seats.

"Hey there!" roared Simms, who had suddenly appeared at the power-deck hatch. "Keep your seat!"

"Who, me?" asked Roger.

"Not your Aunt Tilly, wise guy! Sit down and shut up!"

"Listen," said Roger, "you don't seem to realize—"

"I realize you're going to sit down or else!" snarled Simms.

Roger retreated to his seat and sat down. "Ah, go blast your jets," he grumbled as Simms continued up the aisle to the control deck.

Tom and Astro doubled over with laughter. "Welcome back, Roger," bellowed the big Venusian. "I don't think those girls are the sociable type, anyway."

"Wouldn't you know," moaned Roger, "that space creep had to show up just when I had the whole campaign laid out in my mind." He gazed sadly at the pert heads of the girls in front of him.

Tom gave Astro a wink. "Poor Manning. All set to go hyperdrive and ran into space junk before he cleared atmosphere."

Suddenly another explosion racked the ship and the rockets cut out all together. The passengers began to look around nervously.

"By the craters of Luna, what was that?" demanded Tom, looking at Astro.

"The rockets have cut out," answered the Venusian. "Hope we're out in free fall, beyond the pull of Venus' gravity."

The forward hatch of the passenger cabin opened and Simms reappeared followed by Wallace.

"Take it easy, folks," said Wallace, "nothing to get excited about. We're in free fall, holding a course around the planet. So just sit back and enjoy the view!"

A chorus of sighs filled the cabin and the passengers began laughing and chatting again, pointing out various sights on the planet below them. Smiling, Wallace and Simms marched down the aisle. Suddenly Roger and Tom rose and blocked their path.

"What's up, Wallace?" demanded Tom.

Wallace gave the two boys a hard look. "So it's you, huh? You got a lot of nerve coming aboard this ship."

"If there's something wrong, Wallace," said Tom, "maybe we could give you a hand."

"Get back in your seats," ordered Wallace. "We don't need any cadet squirts getting in our way!"

"Why, you overweight space jockey," snapped Roger, "we know more about spaceships than you'll ever learn!"

"One more crack out of you and I'll blast your ears off!" roared Wallace. "Now sit down!"

Roger's face turned a deep red and he moved toward Wallace, but Tom put out a restraining hand.

"Take it easy, Roger," he said. "Wallace is the skipper of this boiler. In space he's the boss."

"You bet I'm the boss," snarled Wallace. "Now keep that loud-mouthed punk quiet, or I'll wipe up the deck with him and send the pieces back to Space Academy!"

"Hey, Wallace," yelled Simms, who had walked away when the argument started. "Come on. We gotta fix that reactor unit!"

"Yeah—yeah," Wallace called back. He turned to Roger again. "Just remember what I said, cadet!" Brushing the boys aside, he strode down the aisle to join Simms.

As the two men disappeared through the power-deck hatch, Tom turned to Roger and tried to calm him down. "Skippers are skippers, Roger, even aboard a piece of space junk!"

"Yeah," growled Roger, "but I don't like to be called a squirt or a punk! Why, I know more about reactor units than—"

"Reactor units?" broke in Astro from his seat.

"Yeah. Didn't you hear what Simms said?"

"But this is a chemical burner," said Astro. "Why an atomic reactor unit aboard?"

"Might be a booster for extra speed," offered Tom. "And more power."

"On a simple hop like this? Hardly out of the atmosphere?" Astro shook his head. "No, Tom. It doesn't make sense."

"Well," chimed in Roger, "here's something else I've been wondering about. They charge one credit for this ride. Which makes a total of about fifty credits for a capacity load—"

"I get you," Tom interrupted. "It costs at least two hundred credits in fuel alone to get one of these chemical jalopies off the ground!"

Roger looked at Tom solemnly. "You know, Tom, I'd certainly like to know what those guys are doing. You just don't hand out free rides in space."

"How about snooping around?" asked Astro.

Tom thought a moment. "O.K. You two stay here. I'll go aft and see what they're doing."

Tom walked quickly to the stern of the ship, entered the power-deck hatch, and disappeared. Astro and Roger, each taking one side of the ship, strained for a look from the viewports. In a few minutes Tom returned.

"Spot anything?" asked Roger.

"I'm not so sure," answered Tom. "They weren't on the power deck and the cargo hatch was locked. I looked out the stern viewport, but all I could see was a thick black cloud."

"Well, that's no help," said Roger. Suddenly the blond cadet snapped his fingers. "Tom, I'll bet they're smugglers!"

"What?" asked Tom.

"That's it," said Roger. "I'll bet that's it. The concession is just a phony to cover up their smuggling. It lets them take a load of stuff up without a custom's search. Then, when they're far enough out—"

"They dump it," supplied Astro.

"Right!" agreed Tom finally. "What better place to hide something than in space?"

"For someone else to pick up later!" added Roger triumphantly.

When Wallace and Simms returned, the three cadets were busy looking out the viewports. And later, when the spaceship was letting down over the exposition grounds, Tom commented on the ease with which the ship made her approach for a touchdown.

"Roger," asked Tom quietly, "notice how she's handling now?"

"How do you mean?" asked Roger.

"Going out," said Tom, "she wallowed like an old tub filled with junk. Now, while she's no feather, there's a big difference in the way she's maneuvering!"

"Then they did dump something in space!" said Roger.

"I'm sure of it!" said Tom. "And from now on, we're going to keep our eyes open and find out what it is!"

Tom glanced at the astral chronometer over the control board of the Polaris and sighed with relief. It was nine P.M. He turned to the intercom.

"Attention, please! Attention, please! The exhibit is now closing for the night. All visitors will kindly leave the ship immediately." He repeated the announcement again and turned to smile at the last lingering youngster ogling him before being yanked toward an exit by a tired and impatient mother.

The hatch to the radar bridge opened and Roger climbed down the ladder to flop wearily in the pilot's seat in front of the control panel.

"If one more scatterbrained female asks me how the astrogation prism works," groaned the blond cadet, "I'll give it to her and let her figure it out for herself!"

Astro joined them long enough to announce that he had made sandwiches and brewed hot chocolate. Tom and Roger followed him back to the galley.

Sipping the hot liquid, the three cadets looked at each other without speaking, each understanding what the other had been through. Even Astro, who normally would rather talk about his atomic engine than eat, confessed he was tired of explaining the functions of the reaction fuel force feed and the main valve of the cooling pumps.

"The worst of it is," sighed Astro, "they all pick on the same valve. What's so fascinating about one valve?"

Tom's job on the control deck was less tiring, since his was more of a command post, which demanded decisions, as conditions arose, rather than a fixed routine that could be explained. But even so, to be asked over and over what the astral chronometer was, how he could read time on Earth, Mars, Venus, Titan, Ganymede, and all the satellites at the same time was wearing on the toughest of young spirits.

Eager to forget the grueling day of questions and answers, the cadets turned their thoughts to the mysterious midnight activity that had been taking place around the spaceship concession during the last ten days.

"I just can't figure out what those guys are up to," said Roger, blowing on his hot chocolate. "We've watched those guys for over a week now and no one has even come near them with anything that could be smuggled."

"Could be a small package," suggested Astro, his mouth full of ham sandwich. "Somebody could take a ride and slip it to them."

"Hardly," said Tom. "Remember, that ship blasts off like she's loaded to the nose with cargo. And then she comes back like a feather. You can tell by the sound of her jets. So it wouldn't be anything small enough for someone to carry."

"Yeah, I guess you're right," agreed Astro.

"Well," said Tom finally, "I'm stumped. I think the only thing left to do is to decide if it's anything important enough to tell Captain Strong about. Working on the Polaris twelve hours a day and staying up all night to watch those two jokers has me all in."

Roger and Astro looked at each other and then silently nodded their agreement.

"O.K.," said Tom, "we'll go to the skipper's hotel in Venusport and tell him the whole thing. Let's see what he makes of it."

At that moment Captain Strong was in the office of Exposition Commissioner Mike Hawks trying to make sense out of a series of reports that had landed on the commissioner's desk. Hawks watched him carefully as he studied the papers.

"You say this is the ninth report you've received since the fair opened, Mike?" asked Strong finally.

Hawks nodded. He hadn't known whether to laugh off or seriously consider the nine space skippers' reports that the sky over the exposition site was dirty.

"Yes, Steve," he said. "That one came from the skipper of an express freighter. He blasted off this morning and ran through this so-called dirt. He thought it was just a freak of nature but reported it to be on the safe side."

"I don't suppose he took a sample of the stuff?"

"No. But I'm taking care of that," replied Hawks. "There's a rocket scout standing by right now. Want to come along?"

"Let me finish these reports first."

"Sure thing."

As Strong carefully checked each report, Commissioner Hawks rose and began to stride restlessly back and forth across the spacious office. He stopped in front of the window and stared out over the exposition grounds, watching the thousands of holiday visitors streaming in and out of the buildings, all unaware of the strange mystery in the sky above them. Hawks' attention was drawn to the giant solar beacon, a huge light that flashed straight out into space, changing color every second and sending out the message: "Quis separabit homo"—Who shall separate mankind?

This beacon that at the beginning of the exposition had reached into the black void of space like a clean bright ray was now cloudy and murky—the result of the puzzling "dirty sky."

"All right, Mike," Strong announced suddenly. "Let's go."

"Get anything more out of those reports?" asked Hawks, turning back to his desk.

"No," replied the Solar Guard officer. "They all tell the same story. Right after blast-off, the ships ran into a dirty sky."

"Sounds kind of crazy, doesn't it?"

"Crazy enough to check."

Hawks pressed a button on the desk intercom.

"Yes, sir?" replied a metallic voice.

"Have the rocket scout ready for flight in five minutes," Hawks ordered. He snapped off the intercom without waiting for a reply and turned to Strong. "Let's go, Steve."

The two veteran spacemen left the office without further comment and rode down in the vacuum elevator to the highway level. Soon they were speeding out to the spaceport in Hawks' special jet car.

At the blast-pitted field they were met by a young Solar Guard officer and an elderly man carrying a leather case, who were introduced as Lieutenant Claude and Professor Newton.

While Claude prepared the rocket scout for blast-off, Strong, Hawks, and Newton discussed the possibility of lava dust having risen to great heights from another side of the planet.

"While I'm reasonably sure," stated Newton, "that no volcano has erupted recently here on Venus, I can't be sure until I've examined samples of this so-called dirt."

"I'll have Lieutenant Claude contact the University of Venus," said Hawks. "Their seismographs would pick up surface activity."

Claude stuck his head out of the hatch and reported the ship ready for blast-off. Strong followed the professor and Hawks aboard and strapped himself into an acceleration chair. In a moment they were blasting through the misty atmosphere of Venus into the depths of space.

Fifteen minutes later, Hawks and Strong were standing on the hull of the ship in space suits, watching the professor take a sample of a dirty black cloud, so thick it was impossible to see more than three feet. Strong called to the professor through the spacephone.

"What do you make of it, sir?" he asked.

"I wouldn't want to give you a positive opinion without chemical tests," answered the professor, his voice echoing in Strong's fish-bowl helmet. "But I believe it's one of three things. One, the remains of a large asteroid that has broken up. Two, volcanic ash, either from Venus or from Jupiter. But if it came from Jupiter, I don't see how it could have drifted this far without being detected on radar."

Now, holding a flask full of the black cloud, the professor started back to the air lock.

"You said three possibilities, professor," said Strong.

"The third," replied the professor, "could be—"

The professor was interrupted by Lieutenant Claude calling over the intercom.

"Just received a report from the University of Venus, sir!" said the young officer. "There's been no volcanic activity on Venus in the last ten years serious enough to create such a cloud."

Strong waited for the professor's reaction, but the elderly man was already entering the air lock. Before Strong and Hawks could catch up to him, the air-lock hatch slammed closed.

"Hey," exclaimed Strong, "what does he think he's doing?"

"Don't worry about it, Steve," replied Hawks. "He probably forgot we were out here with him, he's so concerned about this dirt. We'll just have to wait until he's out of the air lock."

The Solar Guard officer nodded, then looked around him at the thick black cloud that enveloped the ship. "Well," he said, "one of the professor's theories has been knocked out."

"Yes," replied Hawks. "Which means this stuff is either the remains of a large asteroid or—"

"The third possibility," finished Strong, "which the professor never explained."

Suddenly the air-lock hatch opened again and the two spacemen stepped inside. Closing the hatch behind them, they waited until the pressure was built up again to equal that of the ship, and then they removed their helmets and space suits.

The hatch opened again and the two spacemen entered the air lock

Leaving the air lock and walking down the companionway, Hawks suddenly caught Strong by the arm.

"Have you considered the possibility of this cloud being radioactive, Steve?" he asked.

Strong nodded slowly. "That's all I've been thinking about since I first heard about it, Mike. I think I'd better report this to Commander Walters at Space Academy."

"Wait, Steve," said Hawks. "If you do that, Walters might close the exposition. Wait until you get a definite opinion from Professor Newton."

Strong considered a moment. "I guess a few more minutes won't make a lot of difference," he said finally. He realized how important the exposition was to his old friend. But at the same time, he knew what would happen if a radioactive cloud suddenly settled on the city of Venusport without warning. "Come on. Let's see what the professor has to say about this stuff."

They found the professor on the control deck bending over a microscope, studying samples taken from the flask. He peered intently into the eyepiece, wrote something on a pad, and then began searching through the pages of a reference book on chemicals of the solar system.

Lieutenant Claude stepped up to Hawks and saluted sharply. "Power deck reports they've got a clogged line, sir. It's in the gas exhaust."

Strong and Hawks looked at each other, and then Hawks turned to the young officer. "Send a couple of men outside to clear it."

"Aye, aye, sir," said Claude, and then hesitated. "Shall the men wear lead suits against possible radioactivity, sir?"

Before Hawks could answer, Newton turned to face the three men. The professor was smiling. "No need to take that precaution, Lieutenant. I never did tell you my third opinion, did I, Captain Strong?"

"Why, no, you didn't, sir," said Strong.

The professor held up a sheet of paper. "Here's your answer. Nothing but plain old Venusport topsoil. Pure dirt!"

"What?" exclaimed Hawks hastily, reaching for the paper.

"Well, blast me for a Martian mouse," muttered Strong under his breath. "But how?"

Newton held up his hand. "Don't ask me how it got here. That isn't my line of work. All I know is that, without a doubt, the black cloud is nothing more than dirt. Plain ordinary dirt! And it comes from the area in and around Venusport. As a matter of fact, certain particles I analyzed lead me to believe it came from the exposition site!"

Hawks looked at Newton dumbfounded. "By the craters of Luna, man, we're a thousand miles over the exposition!"

The professor was stubborn. "I can't tell you how it got here, Commissioner Hawks. But I do know it's Venusian dirt. And that's final!"

Hawks stared at the elderly man for a second, still bewildered. Then he suddenly smiled and turned to Claude. "As soon as that exhaust is cleared, blast off for Venusport, Lieutenant. I'm going to find out who dirtied up the sky!"

Two hours later, when Captain Strong returned to his hotel in Venusport with Mike Hawks, he was surprised to see the three cadets of the Polaris crew slumped, sleepy-eyed, on a couch in the lobby.

"What are you doing here, boys?" he asked.

The three cadets came to attention and were wide awake immediately. Tom quickly related their suspicions of Wallace and Simms.

"And we've watched them every night, sir," Tom concluded. "I don't know what it is, but something certainly is going on in that shack they use for an office."

"Yes, sir," agreed Astro, "and no one is going to fool me about a rocket ship. I know when they blast off loaded and return light."

Strong turned to Hawks who said quietly, "Wallace and Simms are the only ones in this whole area that blast off regularly without a customs search."

"You mean," stammered Strong, "Wallace and Simms are dumping"—he could hardly say the word—"dirt in space?"

"They have a ship. The cadets say the ship blasts off loaded and returns light. And we've got the sky full of dirt. Venusian dirt!"

"But why?"

"I suggest we go out to the exposition grounds right now and ask them!" said Hawks coldly. "And believe me, they'd better have some rocket-blasting good answers!"

The great educational exhibits had long been closed and only a few sections of the amusement park of the big exposition remained open. The giant solar beacon, its brilliant colors changing every second, maintained a solemn solitary watch over the exhibition buildings, while here and there groups of fair visitors wandered wearily back to their hotels.

There was a sudden flurry of activity at the space-ride concession. Gus Wallace and Luther Simms tumbled out of the shack and raced into their ship. Once inside the ancient craft, they secured the hatch and turned toward each other smiling broadly. Wallace stuck out his hand.

"Put 'er there, Simms. We did it!"

The two men shook hands heartily.

"By the craters of Luna," said Simms, "I thought we'd never make it! And if we did, that it wouldn't be there!"

"But it was, Simms! It was! And now we've got it!"

"Yeah," agreed the other. "I never worked so hard in all my life. But it's worth it. Are we going to set the Solar Guard back on its ear!"

Wallace laughed. "Not only that, but think of what the boss will say when we show up with it!"

"You know, Wallace," said Simms, a sly look on his face, "we could take it and use it ourselves—"

"Don't even think a thing like that!" snapped Wallace.

"Oh, of course not," said Simms hurriedly. "It doesn't pay to cross the boss. There's enough here for all of us."

"You know," mused Wallace, "there's only one thing I regret."

"What's that?" asked his partner.

"That I didn't get a chance to kick the space dust out of that punk, Cadet Manning!"

"Forget him," said Simms, waving his hand. "You'll meet him again someday. Besides, why think about him, when you've got the whole universe at your finger tips?"

"You're right. But someday I'm going to catch him and tear him apart!" snarled Wallace. "Come on. We've got to change over to atomic drive on this baby. I don't want to hang around here any longer than I have to."

"Yeah," said Simms. "Be pretty stupid if we're caught now!"

The two men climbed down into the power deck and began the job of refitting the freighter from chemical to atomic drive. Having already outfitted the vessel with atomic engines, it was a simple matter to change the exhaust, reset the feed lines, and emplace the protective lead baffles. In an hour the two spacemen were ready to blast off.

"There she is," said Simms, standing back to survey their work. "As fast as anything in space, except the Solar Guard cruisers on hyperdrive."

"O.K.," said Wallace. "Let's get out of here!"

Minutes later, in a jet car speeding along the main highway toward the exposition grounds, Captain Strong, Mike Hawks, and the three cadets of the Polaris saw a rocket ship blast off. They watched it disappear into the dark space above.

"That might be they," said Strong to Hawks. "I'd better alert the patrol ship near the space station and tell them to pick them up."

"That couldn't be Wallace and Simms, sir," said Astro.

"How do you know, Astro?" asked Strong.

"That was an atomic-powered ship. The wagon Wallace and Simms have is a chemical job. I know the sound of her jets almost as well as I do the Polaris."

Hawks looked at Strong.

"You can depend on Astro's opinion, Mike," said Strong. "He was born with a rocket wrench in his hand and cut his teeth on a reactor valve."

They soon reached the outskirts of the exposition grounds and were forced to slow down as they wound their way through the darkened streets. In the amusement section, the last of the whirlaway rides and games of chance had closed down and only the occasional roar of a caged animal in the interplanetary zoo disturbed the night.

Hawks drove the low, sleek jet car around the fair, taking a short cut through the outdoor mercuryball field and pulled up in front of the Polaris.

The five spacemen turned toward the concession site across the promenade and stopped, aghast.

"Gone!" exclaimed Strong. "Astro, you made a mistake! It was their ship we saw blasting off. It's too late to warn the space-station patrol. Wallace and Simms could be anywhere in space now!"

"But, sir," protested Astro, "I'm certain that an atomic-powered ship blasted off. And their old freighter was a chemical burner!"

"Well," said Hawks resignedly, "they're not here."

"Come on," said Strong, getting out of the jet car. "Let's take a look around."

Strong and Hawks hurried across the street to the empty lot and the three cadets followed.

"Take it easy, Astro," said Tom, when he saw the big Venusian gripping his fists in frustration. "Anyone could make a mistake."

"That's just it," said Astro. "I'm not mistaken! Those jokers must have changed over from chemical fuel to reactant drive!"

"But why?" asked Roger. "That would cost more than they could make in ten years of hauling passengers on joy rides!"

Astro whirled around and faced the two cadets. "I'm telling you the ship that blasted off from here was an atomic drive. I don't know any more than that, but I do know that!"

There was a sudden shout from Strong and the three boys hurried to the shack. The Solar Guard captain and the exposition commissioner were standing inside and playing the beam of an electric torch around the walls.

"Looks as though you were right about the atomic drive, Astro," said Strong. He flashed the light into one corner where a tangled jumble of lines lay on the floor. "That's feed-line gear for a chemical burner, and over there"—he played the light on some empty cartons—"is what's left of the crate's lead baffling it shipped in. They must have changed over to atomic drive recently."

Astro accepted the statement with a nod. It wasn't in the nature of the big cadet to boast. Now that the secret of the ship had been resolved, he turned, like the others, to the question of why?

"I think the best thing we can do," said Strong, "is to spread out and search the whole area. Might find something to indicate where they went." Commissioner Hawks nodded his head in agreement.

While Tom, Roger, and Astro searched outside, Strong and Hawks went through the drawers of the dusty desk standing in one corner.

"Nothing here but a record of the flights they made, bills for chemical fuel delivered, and the like," said Hawks at last. "They were losing money on the operation, too. Think they might have just gotten fed up and pulled out?"

Strong was rummaging around in one corner of the shack. "I'd go along with that, but for one thing, Mike," he said. "Take a look at this." He held up a small cloth bag. "There's dirt in the bottom of this bag. And there are about fifty more bags in that corner."

"Dirt!" exclaimed the commissioner.

"Yep," said Strong grimly. "So we found out who was dumping the dirt. But we still haven't found out why."

"Or where it came from," said Hawks.

Strong tossed the bag into the corner. "Well, I guess I'd better make a report to Commander Walters."

Hawks moved to the corner where the pile of chemical feed-line equipment lay on the floor. "Want to take a look at this stuff? Might be something important in it."

Strong thought a moment. "We can have the cadets do that. I want to get this report off to Walters right away, and issue an order to pick up Wallace and Simms."

"On what charges, Steve?" asked the commissioner. "I mean, what's wrong with what they've done?" The commissioner's question was based on one of the cardinal rules among all Solar Guard officers of authority. "Has the man committed any crime?"

Steve realized this and answered slowly. "They've changed over to reactor drive without a license or permission. That's a violation of the space code, section twenty-one, paragraph A. That is punishable by a suspension of space papers, and if the intention proved to be willful neglect of the code, a year on a penal asteroid. I think we can get them on that."

The captain stepped to the door and called the cadets.

"Find anything?" he asked, when they entered the shack.

"Nothing, sir," replied Tom. "Except more evidence that they changed over to atomic drive."

"That's enough" said Strong. "I'm going to send a report to Commander Walters. Is the teleceiver on the Polaris hooked up, Roger?"

"Yes, sir," replied Roger. "But Astro will have to start up the auxiliary generators to give you power."

"Very well, then," said Strong. "Corbett, you give Astro a hand on the power deck. And while we're gone, Manning, you go through that feed-line junk there in the corner and see if there's anything important in it!"

"Aye, aye, sir," replied Roger.

Strong and Hawks, followed by Tom and Astro, left the shack and hurried to the Polaris.

"Easy, Astro," said Strong, standing behind the big cadet. "Pull that line up slowly and gently."

"Yes, sir," gasped Astro. He didn't have to be told to pull the rope with caution. He knew only too well that the slightest jar or bump against the side of the shaft might dislodge Roger's unconscious body from the tangle of line, causing him to fall to the bottom of the shaft. How far down the shaft went, none of the anxious spacemen around the hole in the splintered floor knew. And they didn't want to use Roger's body to find out!

"I'll give you a hand, Astro," said Commissioner Hawks. He reached for the line, but the big cadet warned him away.

"That's all right, sir," he said. "He's almost up now."

Astro pulled gently, hand over hand, until Roger's limp body was a mere foot from the edge.

"Grab him, quick!" he panted.

Immediately Strong and Hawks were down on their knees at the edge of the hole. Each taking an arm, they pulled Roger out and laid him gently on the floor of the shack. They crouched over him and began a quick examination.

"How is he, sir?" asked Tom, hovering anxiously over the still form of his friend. "Will he be all right?"

Strong didn't answer for a moment, continuing his hurried, though careful check. Then he sat back on his heels and sighed in relief. "A few bruises but no broken bones, thank the universe. He's just suffering from shock. A day or so in sick bay and he'll be good as new."

"I'll take him over there right away, Steve," offered Hawks.

"Thanks, Mike," replied Strong. Then as he and the commissioner lifted the still form of the cadet and started to carry him out of the shack, he turned to Astro. "Blast over to the Polaris and call Solar Guard headquarters in Venusport. Tell them to send an emergency crew down here right away."

"Aye, aye, sir," snapped the big Venusian and dashed out of the shack.

Turning back to Hawks, Strong said, "Corbett and I will stay here and try to find out where that shaft leads."

"All right, Steve," nodded the commissioner. "Too bad we had to find out where that dirt came from the hard way."

Reaching the jet car, the two men placed Roger in the back seat, and Hawks slid in under the wheel to start the powerful jets. Just then Astro, racing back from the Polaris, pulled up breathlessly.

"Solar Guard crew is on the way, sir," he reported. He glanced anxiously into the back seat of the jet car.

"All right, Astro," said Strong gently, "take care of Roger." Strong gestured to the back seat and without a word Astro leaped in beside his friend. Hawks stepped on the accelerator and the car shot away in a roar of blasting jets.

Tom and Captain Strong watched the car disappear and then turned back to the shack. Each felt the same emotion, an unspoken determination to see that Wallace and Simms paid dearly for causing the accident.

Re-entering the shack, they began a careful examination of the shaft. Strong played his emergency light down the sides, but the beam penetrated only a short distance.

"We'll leave a note for the emergency crew," said Strong. "Our belt communicators might not work so far underground."

"You're going down, sir?" asked Tom.

Strong nodded. "If necessary. Tie that valve on the end of the rope Astro used and lower it into the shaft. If we can touch bottom with it, we'll climb down and see what Wallace and Simms were after."

"Yes, sir," said Tom. He took the length of rope, tied the heavy metal valve to the end, and began lowering it into the shaft. Strong continued to play the light down the shaft until the valve disappeared into the darkness.

"Rope's getting short, sir," warned Tom. "Only have about two hundred feet left."

Strong glanced at the remaining coils of line on the floor. "I'll get more from the Polaris, if we need it," he said. "How long was that line to begin with?"

"It's a regulation space line, sir," said Tom. "Astro took it out of the emergency locker. It's about twelve hundred feet."

By this time the line, hanging straight down the shaft, had become increasingly heavy. Suddenly it grew slack.

"I think I've hit bottom, sir," cried the cadet. "But I can't pull the valve back up again to make sure."

Strong grabbed the end of the line and helped the cadet pull it back up a short distance. Then they dropped the line again and felt a distinct slackening of weight.

"That's bottom all right," said Strong. "Take this end of the line, run it out of the window on your right, and back through the one on your left. Then make it fast."

"Yes, sir," said Tom. He jumped out of the window, trailing the rope after him, and reappeared almost immediately through the other window to tie a loop in the line. After checking the knot and testing the line by throwing his full weight against it, Strong stripped off his jacket and wrapped it about the line to prevent rope burns. Then, hooking the emergency light on his belt, he stepped off into the shaft. Tom watched his skipper lower himself until nothing but the light, a wavering pin point in the dark hole, could be seen. At last the light stopped moving and Tom knew Strong had reached the bottom.

"Hallooooooo!" The captain's voice echoed faintly up the dark shaft. "The belt communicators don't work!" he yelled. "Come on down!"

"Be right with you, sir!" yelled Tom. He scratched a message on the wooden floor of the shack for the emergency crew. Then he stripped off his jacket, wrapped it around the rope, secured the light to his belt, and stepped off into the darkness.