"One thing you still haven't explained, Tom," Bud remarked after the engineer left them.

"What's that?"

"How are you going to draw power form the sun to operate your repelatron? Wouldn't your solar batteries do the job just as well?"

Tom shook his head. "They just soak up power form the sun's visible light rays. But thatís only a small part of the sun's total output. For this job, I'll need to tap all the energy we can get, including the rays above ultraviolet and below infrared."

"You mean a lot of it's going to waste?"

"Sure is, pal." Tom whipped out his slide rule. "If we could harness all the sun's energy, down here on earth, we'd get more than three horsepower from every square foot of surface exposed to the sunshine."

"Then grab it, Tom." Bud grinned. "But how do you tap all this power?"

"Remember those big gadgets like searchlights on the spaceship cabin?" Tom asked.

Bud nodded.

"Well, those are the conversion units which will collect the sun's energy and change it into electricity by photochemical action."

More than ever the gleaming spaceship looked like huge gyroscope poised on four hydraulic landing struts. At the center was the cube-shaped cabin or fuselage. Auxiliary rocket tubes projected below.

"Those polished cups mounted on the cabin are the energy-conversion units," Tom pointed out. "And as I told you, the repelatron radiators run on those outside tracks. Incidentally, a special meteor-repelling machine will be turned on all the time."

"Thank goodness for that," said Bud. "I'd hate to have a meteor hit us. Say, what's this? Looks like a front porch" he added, as they climbed up to the cabin.

"Landing platform for auxiliary ships," Tom explained.

"You mean this ship will carry smaller crafty?" said Bud.

"That's right. They'll be berthed in here." Entering through an air lock, he showed Bud a large hangar compartment. "Then there's a machine shop for emergency repairs on each side, with laboratories above them."

They walked through the starboard shop, equipped with lathes, welders, and other tools, and entered a small elevator. Tom pressed a button and they zoomed upward.

"This is the top deck," Tom said as they stepped out. They were in a small compartment containing banks of electronic computing gear. "These computers will feed our navigation equipment and also compute the tapes for our automatic pilot when we operate on auxiliary rocket power," he explained.

"This ship is sure loaded with brains!" Bud grinned. "Not counting me."

Next came the ship's control room where the pulps, gauges, and air-conditioning equipment were installed When they entered the flight compartment, Bud's eyes popped when he saw the rows of gleaming dials, levers, and switches.

"What a setup!"

Bucket seats for pilot and copilot stood in front of twin quartz glass view panes. At the left was a huge fluorescent screen and at the right a multi-dial panel labeled with names of the planets and other heavenly bodies.

"I'll check you out on all these controls tomorrow, just before we take her up," Tom said. "Right now, let's see the other sections."

Beyond the flight compartment was another small room full of mysterious dials and electronic gear. "This is the radiation-control room," Tom explained, "for monitoring the gamma and cosmic radiation received by the ship. And this next door leads to the power room, where we handle the electrical output of our solar-conversion units."

Gliding down in another small elevator on the ship's portside, Tom pointed out the rooms that honeycombed the lower level. There were bunkrooms, living quarters, and a galley. On the bottom deck were air and water storage and purification plants, auxiliary engine room, and compartment housing the repelatron gear.

"My head's spinning, genius boy!" Bud said. "With this layout, we could fly to another galaxy!"

"I'll be satisfied if we make the moon." Tom chuckled, adding, "If we do, we'll have sure proof of the whole trip. I have a tape recorder aboard."

The boys climbed up the accommodation ladder and entered the ship's air lock. When they reached the flight compartment, a puzzled look swept over Bud's face. "Hey, you've forgotten something, Tom!" he said.

"What's that?"

"The acceleration cots."

Tom chuckled. "On this ship we don't need them."

"What?" Bud was baffled.

"In a rocket ship you get tremendous acceleration from short blasts of power," Tom explained. "But with our energy-conversion units we can get a steady supply of power from the sun. So we can accelerate gradually to high speed, without taking so many G's all at once."

"Now you're talking!" Bud said enthusiastically. "No more getting the daylights crushed out of us!"

Tom nodded. "It simplifies a lot of things. For instance, we won't need automatic tape control at blast-off, because we can adjust our steering in fine amounts any time we want to."

"Terrific!" Bud said. "Now, how about briefing me on all these control gadgets?"

Tom pointed to a row of indicator lights and push buttons above the pilot's windows. "This is the element selector panel," he said. "As you can see, it lists all the ninety-two natural elements."

"Just push the button for whatever element you want to repel?" Bud asked.

"Right. And these dial switches below let you select the exact isotope. They work through this interplugging board."

"Pretty neat! And this is the astro-gyrocompass, eh?" Bud pointed to an instrument on the central control board.

"Yes -- for steering operations after the ship is underway," Tom told him. "And these big twin dials are the power indicators."

He explained the various levers for operating the directional radiators and auxiliary rockets. Then Bud asked about the huge fluorescent screen on the left.

"It's the space position finder," Tom replied. "Sort of a space radarscope."

He flicked a small toggle switch. As the screen lighted up with ah um, he tuned several knobs. Instantly the lower half of the screen was painted with a reddish phosphorescent glow.

"It'll look like this whenever we've landed," Tom explained. "That red area represents the earth. In fight, we'll see the planets or other objects as round dots, and the color will show us their height above or below our orbital plane."

"How about that panel over on the right?" Bud asked curiously. "The one with all the astro-whoozical names on it."

Tom walked to the right-hand control board, grinning. "As you can see, these dials are labeled for the earth, moon, sun, Mars, Venus, and so on. They tell the distance and relative angle of each body from our spaceship. In other words, they give us an exact reading of the picture shown on the screen."

"But these meters calibrated for thrust -- where do they come in?"

"They tell us how much power we have to feed to the radiators for any desired acceleration," Tom explained.