He was gone and Rioz leaned back. He watched the even green line that was the pulse scanner. He tried the multi-scanner a moment Space was still clear.

He felt a little better. A bad spell is always worse if the Scavengers all about you are pulling in shell after shell; if the shells go spiraling down to the Phobos scrap forges with everyone’s brand welded on except your own. Then, too, he had managed to work off some of his resentment toward Long.

It was a mistake teaming up with Long. It was always a mistake to team up with a tenderfoot. They thought what you wanted was conversation, especially Long, with his eternal theories about Mars and its great new role in human progress. That was the way he said it-Human Progress: the Martian Way; the New Creative Minority. And all the time what Rioz wanted wasn’t talk, but a strike, a few shells to call their own.

At that, he hadn’t any choice, really. Long was pretty well known down on Mars and made good pay as a mining engineer. He was a friend of Commissioner Sankov and he’d been out on one or two short scavenging missions before. You can’t turn a fellow down flat before a tryout, even though it did look funny. Why should a mining engineer with a comfortable job and good money want to muck around in space?

Rioz never asked Long that question. Scavenger partners are forced too close together to make curiosity desirable, or sometimes even safe. But Long talked so much that he answered the question.

“I had to come out here, Mario,” he said. “The future of Mars isn’t in the mines; it’s in space.”

Rioz wondered how it would be to try a trip alone. Everyone said it was impossible. Even discounting lost opportunities when one man had to go off watch to sleep or attend to other things, it was well known that one man alone in space would become intolerably depressed in a relatively short while.

Taking a partner along made a six-month trip possible. A regular crew would be better, but no Scavenger could make money on a ship large enough to carry one. The capital it would take in propulsion alone!

Even two didn’t find it exactly fun in space. Usually you had to change partners each trip and you could stay out longer with some than with others. Look at Richard and Canute Swenson. They teamed up every five or six trips because they were brothers. And yet whenever they did, it was a case of constantly mounting tension and antagonism after the first week.

Oh well. Space was clear. Rioz would feel a little better if he went back in the galley and smoothed down some of the bickering with Long. He might as well show he was an old spacehand who took the irritations of space as they came.

He stood up, walked the three steps necessary to reach the short, narrow corridor that tied together the two rooms of the spaceship.

Once again Rioz stood in the doorway for a moment, watching. Long was intent on the flickering screen.

Rioz said gruffly, “I’m shoving up the thermostat. It’s all right—we can spare the power.”

Long nodded. “If you like.”

Rioz took a hesitant step forward. Space was clear, so to hell with sitting and looking at a blank, green, pipless line. He said, “What’s the Grounder been talking about?”

“History of space travel mostly. Old stuff, but he’s doing it well. He’s giving the whole works—color cartoons, trick photography, stills from old films, everything.”

As if to illustrate Long’s remarks, the bearded figure faded out of view, and a cross-sectional view of a spaceship flitted onto the screen. Hilder’s voice continued, pointing out features of interest that appeared in schematic color. The communications system of the ship outlined itself in red as he talked about it, the storerooms, the proton micropile drive, the cybernetic circuits…

Then Hilder was back on the screen. “But this is only the travel-head of the ship. What moves it? What gets it off the Earth?”

Everyone knew what moved a spaceship, but Hilder’s voice was like a drug. He made spaceship propulsion sound like the secret of the ages, like an ultimate revelation. Even Rioz felt a slight tingling of suspense, though he had spent the greater part of his life aboard ship.

Hilder went on. “Scientists call it different names. They call it the Law of Action and Reaction. Sometimes they call it Newton’s Third Law. Sometimes they call it Conservation of Momentum. But we don’t have to call it any name. We can just use our common sense. When we swim, we push water backward and move forward ourselves. When we walk, we push back against the ground and move forward. When we fly a gyroflivver, we push air backward and move forward.

“Nothing can move forward unless something else moves backward. It’s the old principle of ‘You can’t get something for nothing.’

“Now imagine a spaceship that weighs a hundred thousand tons lifting off Earth. To do that, something else must be moved downward. Since a spaceship is extremely heavy, a great deal of material must be moved downward. So much material, in fact, that there is no place to keep it all aboard ship. A special compartment must be built behind the ship to hold it.”

Again Hilder faded out and the ship returned. It shrank and a truncated cone appeared behind it. In bright yellow, words appeared within it: MATERIAL TO BE THROWN AWAY.

“But now,” said Hilder, “the total weight of the ship is much greater. You need still more propulsion and still more.”

The ship shrank enormously to add on another larger shell and still another immense one. The ship proper, the travel-head, was a little dot on the screen, a glowing red dot.

Rioz said, “Hell, this is kindergarten stuff.”

“Not to the people he’s speaking to, Mario,” replied Long. “Earth isn’t Mars. There must be billions of Earth people who’ve never even seen a spaceship; don’t know the first thing about it.”

Hilder was saying, “When the material inside the biggest shell is used up, the shell is detached. It’s thrown away, too.”

The outermost shell came loose, wobbled about the screen.

“Then the second one goes,” said Hilder, “and then, if the trip is a long one, the last is ejected.”

The ship was just a red dot now, with three shells shifting and moving, lost in space.

Hilder said, “These shells represent a hundred thousand tons of tungsten, magnesium, aluminum, and steel. They are gone forever from Earth. Mars is ringed by Scavengers, waiting along the routes of space travel, waiting for the cast-off shells, netting and branding them, saving them for Mars. Not one cent of payment reaches Earth for them. They are salvage. They belong to the ship that finds them.”

Rioz said, “We risk our investment and our lives. If we don’t pick them up, no one gets them. What loss is that to Earth?”

“Look,” said Long, “he’s been talking about nothing but the drain that Mars, Venus, and the Moon put on Earth. This is just another item of loss.”

“They’ll get their return. We’re mining more iron every year.”

“And most of it goes right back into Mars. If you can believe his figures, Earth has invested two hundred billion dollars in Mars and received back about five billion dollars’ worth of iron. It’s put five hundred billion dollars into the Moon and gotten back a little over twenty-five billion dollars of magnesium, titanium, and assorted light metals. It’s put fifty billion dollars into Venus and gotten back nothing. And that’s what the taxpayers of Earth are really interested in— tax money out; nothing in.”

The screen was filled, as he spoke, with diagrams of the Scavengers on the route to Mars; little, grinning caricatures of ships, reaching out wiry, tenuous arms that groped for the tumbling, empty shells, seizing and snaking them in, branding them MARS PROPERTY in glowing letters, then scaling them down to Phobos.

Then it was Hilder again. “They tell us eventually they will return it all to us. Eventually! Once they are a going concern! We don’t know when that will be. A century from now? A thousand years? A million? ‘Eventually.’ Let’s take them at their word. Someday they will give us back all our metals. Someday they will grow their own food, use their own power, live their own lives.