"Eeeeeeoooooooow!" Astro's bull-like roar shattered the silence of the desert. "There—up ahead, Tom—Roger—a building!"

Tom and Roger stopped and strained their eyes in the bright sunshine.

"I think you're right," said Tom at last. "But I doubt if anyone's there. Looks like an abandoned mining shack to me."

"Who wants to stand here and debate the question?" asked Roger, and started off down the side of the canal at a lope, with Astro and Tom right behind him.

During the last three days the boys had been living off the contents of the last remaining food container and the few lichens they found growing along the canal. Their strength was weakening, but with an abundant supply of water near at hand and able to combat the sun's heat with frequent swims, they were still in fair condition.

Tom was the first to reach the building, a one-story structure made of dried mud from the canal. The shutters and the door had long since been torn away by countless sandstorms.

The three boys entered the one-room building cautiously. The floor was covered with sand, and sand was piled in heaping drifts in front of the open windows and door.

"Nothing—not a thing," said Roger disgustedly. "This place must be at least a hundred and fifty years old."

"Probably built by a miner," commented Tom.

"What do you mean 'nothing'?" said Astro. "Look!"

They followed Astro's pointing finger to the ceiling. Crisscrossed, from wall to wall, were heavy wooden beams.

"Raft!" Tom cried.

"That's right, spaceman," said Astro, "a raft. There's enough wood up there to float the Polaris. Come on!"

Astro hurried outside, with Tom and Roger following at his heels. They quickly climbed to the roof of the old building and soon were ripping the beams from the crumbling mud. Fortunately the beams had been joined by notching the ends of the crosspieces. Astro explained that this was necessary because of the premium on nails when the house was built. Everything at that time had to be hauled from Earth, and no one wanted to pay the price heavy nails and bolts demanded.

One by one, they removed the heavy beams, until they had eight of them lined up alongside the edge of the canal.

"How do we keep them together?" asked Roger.

"With this!" said Tom. He began ripping his space cloth into long strips. Astro and Roger tugged at the first beam. At last they had it in the water.

"It floats," cried Astro. Tom and Roger couldn't help but shout for joy. They quickly hauled the remaining beams into the water and lashed them together. Without hesitation, they shoved the raft into the canal, climbing aboard and standing like conquering heroes, as the raft moved out into the main flow of the canal and began to drift forward.

"I dub thee—Polaris the Second," said Tom in formal tones and gave the nearest beam a kick.

Astro and Roger gave a lusty cheer.

Steadily, silently, the raft bore them through the never-changing scene of the canal's muddy banks and the endlessness of the desert beyond.

Protecting themselves from the sun during the day by repeated dunkings in the water, they traveled day and night in a straight course down the center of the canal. At night, the tiny moon, Deimos, climbed across the desert and reflected light upon the satin-smooth water.

The third day on the raft they began to feel the pangs of hunger. And where during their march through the desert, their thoughts were of water, now visions of endless tables of food occupied their thoughts. At first, they talked of their hunger, dreaming up wild combinations of dishes and giving even wilder estimates of how much each could consume. Finally, discovering that talking about it only intensified their desire, they kept a stolid silence. When the heat became unbearable, they simply took to the water. Once Tom's grip on the raft slipped and Roger plunged in after him without a moment's hesitation, only to have Astro go in to save both of them.

On and on—down the canal, the three boys floated. Days turned into nights, and nights, cooling and refreshing, gave way to the blazing sun of the next day. The silent desert swept past them.

One night, when Astro, unable to sleep, was staring ahead into the darkness, he heard a rustling in the water alongside the raft. He moved slowly to the edge of the raft and peered down into the clear water.

He saw a fish!

The big cadet watched it dart around the raft. He waited, his body tense. Once the fish came to the edge of the raft, but before Astro could move his arm, it darted off in another direction.

At last the fish disappeared and Astro sank back on the timbers. He trailed one hand over the side in the water, and suddenly, felt the rough scales of the fish brush his fingers. In a flash, Astro closed his hand and snatched the wriggling creature out of the water.

"Tom—Roger—" he shouted. "Look—look—a fish—I caught a fish with my bare hands!"

Tom rolled over and opened his eyes. Roger sat in bewilderment.

"I watched him—I was watching him and then he went away. And then I held my hand over the side of the raft and he came snooping around and—well, I just grabbed him!"

He held the fish in the viselike grip of his right hand until it stopped moving.

"You know," said Tom weakly, "I just remembered. When we were in the Science Building in Atom City, one of their projects was to breed both Earth and Venus fish in the canals."

"I am going to shake, personally, the hand of the man who started this project when we get back to Atom City," said Astro.

Suddenly Roger gripped Tom's arms. He was staring in the direction the raft was going. "Tom—" he breathed, "Astro—look!"

They turned and peered into the dusk. In the distance, not a mile away, was the huge crystal-clear dome of the atmosphere booster station, its roaring atomic motors sending a steady purring sound out across the desert.

"We made it," said Tom, choking back the tears. "We made it!"

"Well, blast my jets," said Astro. "We sure did!"

"And you mean to tell me, you walked across that desert?" asked Captain Strong.

Tom glanced over at Astro and Roger. "We sure did, sir."

"With Astro doing the last stretch to the canal carrying me and dragging Tom," said Roger as he sipped his hot broth.

The room in the chief engineer's quarters at the atmosphere station was crowded with workers, enlisted Solar Guardsmen and officers of the Solar Guard. They stood around staring in disbelief at the three disheveled cadets.

"But how did you ever survive?" asked Strong. "By the craters of Luna, that blasted desert was hotter this past month than it has ever been since Mars was first colonized by Earthmen. Why—why—you were walking through temperatures that reached a hundred and fifty degrees!"

"You don't have to convince us, sir," said Roger with a smile. "We'll never forget it as long as we live."

Later, when Tom, Roger and Astro had taken a shower and dressed in fresh uniforms, Strong came in with an audioscriber and the three cadets gave the full version of their adventure for the official report back to the Academy. When they had finished, Strong told them of his efforts to find them.

"We knew you were in trouble right away," said Strong, "and we tracked you on radar. But that blasted storm fouled us all up. We figured that the sand would have covered up the ship, and that the chances of finding you in a scout were very small, so I got permission from Commander Walters to organize this ground search for you." He paused. "Frankly we had just about given up hope. Took us three weeks finally to locate the section of desert you landed in."

"We knew you would come, sir," said Tom, "but we didn't have enough water to wait for you—and we had to leave."

"Boys," said Strong slowly, "I've had a lot of wonderful things happen to me in the Solar Guard. But I have to confess that seeing you three space-brained idiots clinging to that raft, ready to eat a raw fish—well, that was just about the happiest moment of my life."

"Thank you, sir," said Roger, "and I think I can speak for Tom and Astro when I say that seeing you here with over a hundred men, and all this equipment, ready to start searching for us in that desert—well, it makes us feel pretty proud to be members of an outfit where the skipper feels that way about his crew!"

"What happens now, sir?" asked Tom.

"Aside from getting a well-deserved liberty, it's back to the old grind at the Academy. The Polaris is at the spaceport at Marsopolis, waiting for us." He paused and eyed the three cadets with a smile. "I guess the routine at Space Academy will seem a little dull now, after what you've been through."

"Captain Strong," said Astro formally, "I know I speak for Tom and Roger when I say that routine is all we want for a long time to come!"

"Amen!" added Tom and Roger in unison.

"Very well," said Strong. "Polaris unit—Staaaaand TO!"

The three boys snapped to attention.

"You are hereby ordered to report aboard the Polaris at fifteen hundred hours and stand by to raise ship!"

He returned their salutes, turned sharply and walked from the room.

Outside, Steve Strong leaned against the wall and stared through the crystal shell of the atmosphere station into the endless desert.

"Thank you, Mars," he said softly, "for making spacemen out of the Polaris crew!" He saluted sharply and walked away.

Tom suddenly burst from the room with Roger and Astro yelling after him.

"Hey, Tom, where you going?" yelled Roger.

"I've got to get a bottle of that water out of the canal for my kid brother Billy!" shouted Tom and disappeared down a slidestairs.

Roger turned to Astro and said, "That's what I call a real spaceman."

"What do you mean?" asked Astro.

"After what we've been through, he still remembers that his kid brother wants a bottle of water from a canal as a souvenir!"

"Yeah," breathed Astro, "Tom Corbett is—is—a real spaceman!"