Outside Tycho Station on the Moon, Jess Brinker showed Arne Copeland the odd footprints made in the dust by explorers from Mars, fifty million years ago. A man-made cover of clear plastic now kept them from being trampled.

“Who hasn’t heard about such prints?” Copeland growled laconically. “There’s no air or weather here to rub them out--even in eternity. Thanks for showing a fresh-arrived greenhorn around...”

Copeland was nineteen, tough, willing to learn, but wary. His wide mouth was usually sullen, his grey eyes a little narrowed in a face that didn’t have to be so grim. Back in Iowa he had a girl. Frances. But love had to wait, for he needed the Moon the way Peary had once needed the North Pole.

Earth needed it, too--for minerals; as an easier, jump-off point to the planets because of its weak gravity; as a place for astronomical observatories, unhampered by the murk of an atmosphere; as sites for labs experimenting in forces too dangerous to be conducted on a heavily-populated world, and for a dozen other purposes.

Young Copeland was ready for blood, sweat, and tears in his impulse to help conquer the lunar wastes. He sized up big, swaggering Jess Brinker, and admitted to himself that this man, who was at least ten years his senior, could easily be a phony, stalking suckers. Yet, Copeland reserved judgment. Like any tenderfoot anywhere, he needed an experienced man to show him the ropes.

He already knew the Moon intimately from books: A hell of silence, some of it beautiful: Huge ringwalls. Blazing sunlight, inky shadow. Grey plains, black sky. Blazing stars, with the great blurry bluish globe of Earth among them. You could yearn to be on the Moon, but you could go bats and die there, too--or turn sour, because the place was too rough for your guts.

Afield, you wore a spacesuit, and conversed by helmet radiophone. Otherwise you lived in rooms and holes dug underground, and sealed up. The scant water you dared use was roasted out of gypsum rock. The oxygen you breathed was extracted from lunar oxides by a chemical process. Then air-rejuvenator apparatus reseparated it from the carbon-dioxide you exhaled, so that you could use it over and over.

Copeland had read the tales: With that kind of frugality as the price of survival, lunar prospectors could turn selfish to the point of queerness. Afraid somebody might follow them to their mineral claims, they’d take more pains to leave as little spoor as possible than a fox being tracked by dogs.

“Speaking of how footprints last around here,” Copeland remarked for the sake of conversation, “I understand you’ve got to be careful--stick to high ridges, and to parts of the flat maria where there’s no old volcanic ash or dust of thermal erosion.”

“Guys who do that are misers and old women, kid,” Brinker scoffed. “Hell--it sure ain’t because they’re modest that they’re so cautious! Me--I do things right.”

He lifted a foot from the dust beside the path, revealing the mark of the specially etched steel sole of his spaceboot. A name was stamped across the print: BRINKER.

“I’m proud of where I’ve been and where I’m going--like a true explorer,” the big man said. “Get some soles like mine made for yourself, fella, and come along with me.”

Copeland was intrigued. “Let me think about it a little.”

During the next few hours he heard quite a lot.

A big, blonde nurse--one of the two women in the sealed warrens of Tycho Station, said: “Young man, I love Jess Brinker. But keep away from him, or you’ll wind up in the prison pits, or worse.”

And Copeland heard about Tom Brinker, Jess’ dad--the kind of swindler always found in rough new territory, anywhere. He had promoted the idea of a real city on Lunar. Yeah--one with trees and flowers. What sentimental bait that was for home-starved, desolation-sick wanderers! No wonder somebody had murdered him recently.

By common opinion, twenty-odd years was the only difference between Jess and his father. “Stay clear,” was the warning; the name of Brinker was mud and poison.

Arne Copeland was a cagey youngster; nobody influenced him when he made up his mind. He was no cow-eyed hero-worshipper; yet, on his own, he kind of liked the large, battered, egotist. Copeland knew that he was an egotist himself. He also knew that merely to be on the sketchily-explored Moon was to take chances.

So he said “Okay,” to Brinker, and got some metal boot-soles made, with his name etched into them in reverse, as in a rubber stamp.

Under packs that no coolie could ever have lifted against Earth gravity, they left Tycho Station and moved toward the fringe of that lunar hemisphere which is never seen from Terra--though it is no different from the visible half in general character.

Wherever their feet found a medium that would take an impression, they left their trademark behind them. Copeland could brush a name out with a glove; otherwise those names were about as permanent as if carved from granite, for there was no wind to blow the dust, and no rain to wash it away. Passing tractor-caravans would never blot out all of the footprints. Not in ages of time.

“At least we got us a monument, Jess,” Copeland said once, feeling somewhat thrilled. “That’s what guys out exploring and prospecting need. A legend. A reputation.”

Jess Brinker’s eyes narrowed, making him look sinister. “Yeah, Cope,” he drawled. “But in my case it’s a counter-reputation, with a little of Robin Hood thrown in, to help blow the stink of my Old Man off me. I want some friends and backing, so I can do what Dad really wanted to do--though he was as much of a rogue as a saint. You listening, Cope?”

Copeland kept his face stony. “Tell me what you want to, and then stop,” he said softly.

“Thanks,” Brinker answered. “It doesn’t matter too much that I can guess who killed Pop, and would like to square things. Yeah, a hatchet-faced ex-partner who turned pious and legal on the outside, after he got the breaks. How old is that story, I wonder? ... It doesn’t even rile me terribly, knowing that Dad wasn’t all crook, knowing he believed his idea was good for everybody, and was trying to get funds to put it across.”

Brinker sighed and went on: “The idea is the important thing, Cope. A place with trees and flowers, a city, maybe--an antidote for the Moon’s desolation. Anyone here feels the need in his bones and nerves. But it would take more air and water than could ever be imported, or drawn from the lunar crust. You wouldn’t know it on the dead surface, but two hundred miles deep in the Moon there’s still molten lava, plentiful water in the form of steam, volcanic carbon-dioxide gas--the makings of oxygen. There’s nitrogen, too.

“How to reach that stuff is the question. Drills break under the pressure of depth at a tenth of the distance. Pop’s idea involved Brulow’s Comet, which will be coming back sunward from far space in three years. Imagine--a comet! It could be dangerous, too; nobody could ever get permission for an attempt.”

Brinker paused again. Copeland and he were plodding through a jagged valley. The stars were merciless pinpoints, the silence brittle and grating.

“But there must be a way of blasting down to those life-giving raw-materials, Cope,” Brinker continued. “Maybe with atomic explosive. Experiments call for funds and backing. So I save my money, and wish I had a head for making it faster. And I look for weak spots in the lunar crust with radar. And I try to get people to know I’m around, and to like me...”

Copeland realized that what he had just heard could be a line of malarky meant to kid a yokel, or a bid to get him involved in something. But he found himself kind of falling for the yarn. More than ever he suspected that folks were wrong about Jess Brinker; his warning instincts were being lulled to sleep.

Month-long lunar days passed, while the two men ranged over a segment of the hidden hemisphere. They trod plains and crater-walls unsullied by human feet before; they took photographs to be sold to the Lunar Topographical Commission; they located deposits of radioactive metals, which could be registered for investigation by an assaying party, and for possible royalties. Periodically they visited scattered supply stations, and then set out once more.

Such a life had its poisons even for Brinker and Copeland, who were braced for meeting the unknown and the strange.

Living in space suits for weeks at a time; smelling their own unwashed bodies; slipping an arm out of a heavy sleeve to draw food through a little airlock in their armor’s chestplate; knowing, in spite of effective insulation, that the heat of day exceeded the boiling point of water, and that the cold of the protracted night, when usually they continued their explorations with the aid of ato-lamps, hovered at the brink of absolute zero--all those things had a harsh effect on nervous-systems.

They found two human corpses. One had been crushed in a long fall, his spacesuit ripped open; he was a blackened mummy. The other was a freckled youth, coffined in his armor. Failure of its air-rejuvenator unit had caused asphyxia. What you did for guys like this was collect their credentials for shipment home.

Copeland also found a Martian--inside its transparent version of a spacesuit, for the ancient Moon had been much the same as now. The being was dead, of course. Its brain-case had been a sac; its tentacles were like a snarl of age-hardened leather thongs.

Lying near it was an even greater rarity--the remains of a different sort of monster from the planet that had been literally exploded in a war with Mars, to form the countless fragments that were the asteroids. That much of remote history was already known from the research-expeditions that had gone out to the Red Planet, and beyond.

The queer, advanced equipment of these two beings from two small, swift-cooling worlds--which had borne life early, and whose cultures had rivalled briefly for dominance of the solar system until they had wiped each other out those fifty million years ago--lay scattered near them. It was still as bright and new as yesterday, preserved by the Moon’s vacuum: Cameras, weapons, instruments--rich loot, now, to be sold to labs that sought to add the technology of other minds to human knowledge.

For a year, things went well. The names, BRINKER and COPELAND, footprinted into the lunar dust, helped build the new reputation that Brinker wanted. Copeland and he were a hard-working team; they covered more ground than any other Moon explorers.

The fights that Brinker got into with other toughs at the various supply stations, and never lost, added to the legend--that old Tom’s son was savage and dangerous, but with a gentler side. For instance he once carried a crazed Moon-tramp, whom Copeland was too slight to have handled for a minute, fifty miles on his back to a station. Oh, sure--the stunt could be pure ballyhoo, not charity. But Copeland knew that more and more people had begun to admire his buddy.

Brinker never found a weak spot in the lunar crust. “It’s always about two hundred miles deep, Cope,” he said. “Lots thicker than Earth’s shell, because the Moon, being smaller, cooled more. But don’t worry; nothing is impossible. Soon I’ll have enough money to make minor tests. And maybe enough friends for serious support.”

Yeah--maybe it was all just a brain-bubble. But Copeland had seen enough of desolation to grind the spirit of the Brinker idea into his bones--even if he didn’t think it was quite practical.

“I’ll throw my dough in with yours, Jess,” he said.

Their named bootprints helped build their fame as explorers; but there was a flaw and an invitation here which they both must have realized--and still faced as a calculated risk.

A lunar day later, they were plodding through the Fenwick mountains on the far hemisphere, when streams of bullets made lava chips fly.

As they flopped prone in the dust, a scratchy voice chuckled: “Hello, Brinker. Maybe you and your pal want my bunch to escort you back to Tycho Station. We might as well have the reward. Robbery of a minerals caravan and three killings, they say. It’s terrible how you scatter your tracks around...”

Brinker grasped Copeland’s wrist to form a sound-channel, so that they could converse without using their radiophones. “That was Krell talking,” he said. “Dad’s old partner.”

Luckily, it was not many hours to sunset. The mountain ridges, slanting up to the peaks, cast inky shadows that could hide anything. Brinker was canny; while more bullets spurted, he led a dash back to a ridge-shadow that went clear to the range-crest. Even with bulky packs, climbing was a lot faster than on Earth, where things weigh six times as much.

So they got away, over the mountains. The black night of the far side of the Moon, where Earth never shines, hid them.

“Making boot-soles with our names on them,” Brinker growled bitterly, using the radiophone at reduced range. “The crudest kind of frameup.”

“Your Krell is quite a man,” Copeland stated.

“He could have arranged all of it--sure,” Brinker answered. “He knows I suspect that he finished Pop, so I’m dangerous to him. He might hate me, too, as part of my Old Man--sort of ... Whatever it was he got sore about, originally--money or principle, no doubt ... Besides, I don’t think he wants the Moon to be a little more livable. It would encourage too many colonists to come, increase metals production, spoil prices, cheapen his claims. He’s a corny man, with all the corny reasons...

“He, and some of his guys, could have robbed and killed and left footprints like ours. But any other lugs, seeking someone else to blame for their crimes, could have done all that. If that is so, Krell has got me even legally--without blame to himself.”

“Footprints!” Copeland snapped. “They’re so obviously a frame that it’s silly; anyone could see that! Another thing--maybe Krell was kidding, scaring us by saying that we are wanted. Tell you what, Jess: In any case I won’t seem as guilty as you; I’ll go back alone to Tycho Station, and clear us both.”

“You’re an optimist, ain’t you?” Brinker laughed. “Krell wasn’t kidding; and in a rough place like the Moon, justice jumps to conclusions and gets mean, fast. Sure, the purpose of the footprints is obvious. But I’ve been fighting uphill against my Old Man’s reputation for a long time. Who’s gonna say I haven’t backslid? What I want to accomplish is tough enough with everything in my favor.”

Brinker’s voice was now a sinister rumble with a quiver in it. Arne Copeland turned wary again; he had never lost entirely the deepseated notion that Brinker might cause him misfortune.

“So now what?” he demanded softly, flashing his ato-light beam against Brinker’s face-window, so that he could see his expression. Copeland meant to forestall danger aggressively.

But as the darkness between them was swept aside, he also saw the muzzle of Brinker’s pistol levelled at him. The bigger man’s grin was lopsided. “I’d give you my neck, Cope,” he rumbled. “But I’d give both our necks for you-know-what. Now, because that’s all there’s left, I’m gonna try it Pop’s crazy way. You’re gonna help. If you and I can last through a couple of years of real silence and solitude, it might have a chance. I got a ship hidden. Give me your gun. Easy! If you think I wouldn’t shoot, you’re a fool. Now I’ll wire one of your wrists to mine; we’ve got a long march ahead.”

Some march it was! Copeland was fiercely independent. The warnings about Brinker had gone to waste; so had his own wariness. Bitterness made him savage. The harshness of the Moon still ached in his guts--he wanted the steam and gases of its interior tapped and used, yes--but by some reasonable means. Jess Brinker must be truly Moon-balmy, now. Desolation-nuts. Wild for the sight of growing things. Else how could he think seriously of using Brulow’s Comet? Was it hard to guess how? Copeland knew that he and Brinker had courage, and willingness to work for a sound purpose. But to trade long effort and hardship in a proposition that courted suicide, even in its probable failure--and wide destruction if it managed to be successful--was worse than folly.

So, when these meanings became clear in his mind, he wrestled Brinker at every turn. Twice he almost won. He argued and cursed, getting nowhere. He defied Brinker to shoot him. The big man didn’t do that. But at last Brinker jabbed a hypodermic needle--part of the regulation medical kit--through the flexible rubberized fabric of the elbow-joint of Copeland’s spacesuit, and into his arm.

Many hours later, and many miles farther into the mountainous country, Copeland awoke in a cavern with glassy walls, illuminated by Brinker’s ato-light. Brinker stood near where he lay. He seemed just grimly good-humored.

“This is an old Martian supply depot, Cope,” he offered. “I found it before I knew you, and I kept it in reserve for possible trouble, like now. I knew I could convert its contents to considerable money at any time. So it was like a bank-account, and a last resort, too. There’s even a small Martian spaceship; only three others have ever been found, intact. I also cached some Earthly instruments here. You can bet I didn’t leave any tracks for miles around.”

Copeland’s gaze caught the errie gleam of the strange little craft. He saw the stacks of oddly-made boxes and bales. His hackles rose as he thought of a senseless plunge into unplumbed distance.

“Unwire my hands, Jess!” he coaxed again, trying to control fury. “Get wise! Damn you--you’re more dangerous as an altruist than any crook could be!”

Brinker’s laugh was sharp, but his eyes held real apology. “Want to help me ready and load the ship?” he said almost mildly. “No--I guess not; you aren’t quite in a cooperative frame of mind, yet. I’ll need you later. Sorry, but you’re the only guy around, Cope.”

Brinker blasted queer bulkheads out of the ship, in order to make it habitable for humans. The exit of the cavern had been masked with debris, but now he cleared it. He tossed Copeland aboard and took off into the lunar night.

The vast journey lasted for months. Once Brinker said to his sullen, and again partially-drugged, captive: “Maybe in two years, if we’re very lucky, we’ll be back.”

Hurtling outward, they passed the orbits of Mars, the asteroids, Jupiter, and Saturn. There, with Earth-made instruments, Brinker located what he sought: Brulow’s Comet.

So far from the sun, where the fluorescence-inducing radiations were thinned almost to nothing, it glowed hardly at all. And it had almost no tail; it was only a gigantic, tenuous ghost, with a core of stone and magnetic iron fragments.

Still dazed, Copeland thought about comets. Wanderers, following elongated orbits that loop tight around the sun at one end and plumb the depths of space at the other. Of all large forms moving through the void, they were the least dense. In coma and tail, they were only intensely rarefied and electrified gas. The great enigma about them was that things so deficient in mass and gravity could hold onto even that much atmosphere for long. Perhaps new gases were baked out of the meteoric core, each time a comet was close to the sun; maybe some of them even renewed their atmosphere periodically, by capturing a little of the tenuous substance of the solar corona, during their very near approaches to it.

Brulow’s Comet was on the sunward swing, now, gaining speed under solar gravitation; but it still had a long ways to go. Brinker guided the ship down through its coma and toward its lazily-rotating nucleus, where thousands of fragments of iron and rock swirled around their common center of gravity.

The chunks clattered against the craft’s metal hull, but did no damage at their low speed. Brinker brought the ship to rest at the center of the nucleus, where there was one solid mass of material a hundred yards in diameter.