"With the interstellar drive, Donald. It's been in existence for decades, in fact for nearly half a century. Several explor- atory voyages were made with it right after it was discovered, all of them highly successfulthough you'll find no mention of them in the press of the time. Port couldn't see any profit emerging out of interstellar flight and suppressed the news, sequestered the patents, destroyed the records of the trips insofar as it could. But all the Port ships have the overdrive, just in case. Even our ship has it. So does your ferry-pilot friend up there."

Sweeney shut up.

"The thing is this: most planets, even right here inside the solar system, won't sustain domes to begin with, and can't be terraformed in any even imaginable way. Jupiter, for in- stance. And too many others will yield to either procedure too slowly, and too unprofitably, to tempt Port. Over interstellar distances, Port won't even try, since there'd be no trade or traffic it could collect against.

"Pantropy was the obvious answernot for Port, certainly, but for man's future in general. Somehow, my father sold that idea to some politicians, and to some people with money, too. He was even able to find several survivors of those early interstellar expeditions, people who knew some of the extra- solar planets and the operation of the overdrive. All these people wanted to make at least one demonstration experiment in pantropy, an open-ended one which would lead to others if it succeeded. .

"We are that experiment: this colony on Ganymede.

"Port had it outlawed before it was fairly started, but by the time they found the Moon labs it was too late; we got away. It was then that they put teeth into the laws, and made them retroactive; they had to kill pantropy, and they knew it.

"And that is why, our very existence is a crime, Donald.

And it is an absolute requirement of Port's policy that the colony be a failure, and that they be able to prove it. That's why they want us back. They want to be able to exhibit us, to show what helpless freaks we are on Earth, and to fell their people that we couldn't get along on Ganymede either, and had to be bailed out of our own mess.

"After thatwell, there are those phony commerce-raiding charges you told me about. We'll be tried. We'll be executed, most likely, by exposing us in public to Earth-normal condi- tions. It would be a fine object-lesson; indeed, the finishing touch."

Sweeney crouched down in his chair, utterly revolted by the first complete emotion he had ever experienced: loathing for himself. He understood, now, the overtones in Pullman's voice. Everyone had been betrayedeveryone!

The voice went on without mercy, piling up the ashes. "Now, as for the project, our project that is, that's equally as simple.

We know that in the long run human beings can't colo- nize the stars without pantropy. We know that Port won't allow pantropy to be used. And we know, therefore, that we ourselves have to carry pantropy to the stars, before Port can head us off. One, two, three, infinity.

"So that's what we're going to do, or were going to do.

We've got our old ship fitted out for the trip, and we've got a new generation of childrenjust a small numbertrained to operate it, and adapted forwell, for someplace. The kids can't live on Earth, and they can't live on Ganymede; but they can live on one of six different extra-solar planets we've picked outeach one of which is at a different compa.s.s-point, and at a different distance from Sol. I know the names of only two of them, the kids are the only ones who know the rest.

Which one they'll actually go to will be decided only after they're aloft and on their way. n.o.body who stays behind will be able to betray them. Earth will never find them.

'There will be the beginning of the most immense 'seed- ing program' in man's history: seeding the stars with people.

"// we can still manage to get it off the ground."

In the silence that followed, the door of RuUman's office opened quietly, and Mike Leverault came in, looking pre- occupied and carrying a clipboard. She stopped when she saw them, and Sweeney's heart constricted on the thawing slush inside its stiffly pumping chambers.

"Excuse me," she said. "I thought . . . Is there something wrong? You both look so grim"

"There's something wrong," RuUman said. He looked at Sweeney.

A corner of Sweeney's mouth twitched, without his willing it. He wondered if he were trying to smile, and if so, about what.

"There's no help for it," he said. "Dr. Rullman, your colo- nists will have to revolt against you."

The starsh.e.l.l burst high, perhaps three miles up. Though it was over the western edge of the plateau, enough light spilled down to the floor of the Gouge to checker the rocking, growl- ing halftrack.

The sound, however, was too faint to break through the noise of the turbines, and Sweeney wasn't worried about the brief light. The truck, pushing its way north at a good twenty miles an hour beneath the wild growth, would be as difficult to detect from the air as a mouse running among roots.

Besides, n.o.body would be likely to be looking into the Gouge now. The evidences of battle sweeping the high- lands were too compelling; Sweeney himself was following them tensely.

Mike was doing the driving, leaving Sweeney free to crouch in the tool- and instrument-littered tonneau by the big alum- inum keg, watching the radar screen. The paraboloid basket- work of the radar antenna atop the truck was not sweeping; it was pointing straight back along the way he and Mike had come, picking up a microwave relay from the last automatic station that they had pa.s.sed. The sweeping was being done for Sweeney, by the big radio-telescope atop Howe's pi.

Sweeney paid little attention to the near, low, fast streaks on the screen. They were painted there by rocket ordnance of low calibrea part of the fighting which had no bearing on the overall pattern. That pattern was already clear: it showed, as it had for days, that the insurgent forces still held the mountain and its heavy weapons, but that the attacking salient from the loyalists' camp up north was maintaining the ini- tiative, and was gathering strength.

It had developed into a running stalemate. Though the in- surgents had obviously managed to drive the loyalists out of Howe's pi, perhaps by some trick with the ventilators, perhaps by some form of guerrilla warfare, they were equally evi- dently no match for the loyalists in the field. There they were losing ground twice as fast as they had originally taken it.

The supporting fire from the mountain didn't seem to be helping them much; it was heavy, but it was terribly inaccur- rate. The frequent starsh.e.l.ls told their own story of bad visi- bility and worse intelligence. And the loyalists, ousted though they were, had all the planes; they had the effrontery to fly them over the lines with riding lights.

What the loyalists would do when confronted with the problem of retaking the mountain was another question.

Nothing short of very heavy stuff would make much of a dent on Howe's pi. And, even overlooking the fact that the heavy stuff was all inside the mountain, it would be suicide for either force to use it on Ganymede. The fighting hadn't become that bitter, yet. But it yet might.

And the Earth ships that showed on the screen inside the halftrack knew it. That much showed clearly by their dispo- sition. They were there, almost surely, because they had de- duced that Sweeney was leading the insurgentsbut they showed no desire to draw in and give Sweeney a hand. In- stead, they stood off, a little inside the orbit of Callisto, about 900,000 miles from Ganymedefar enough to give them- selves a good running start if they saw an atomic spark on Ganymede, close enough to bail Sweeney out once it seemed that he had gained the victory anyhow.

Mike's voice, shouting something unintelligible, came back to him mixed in with the roaring of the halftrack's turbines.

"What's the matter?" he shouted, c.o.c.king his head.

". . . that rock-tumble ahead. If it's as . . . before . . . prob- ably break the beam."

"Stop her," Sweeney shouted. "Want another reading."

The halftrack halted obediently, and Sweeney checked his screen against RuUman's readings, which showed on tumblers snicking over on a counter near his elbow. It checked; 900,- 000 was close enough. Maybe a little closer, .but not much.

The wave-front of a full satellary explosion would cross that distance in about five seconds, carrying instant obliteration with it; but five seconds would be long enough to allow the automatics on the Earth ships to slam them away on trans- . finite drive.

He slapped her on the shoulder, twice. "Okay so far. Go ahead."

Her reply was lost, but he saw her crash-helmet nod, and the truck began to cant itself slowly and crazily up a long, helter-skelter causeway of boulders and rubble: a sort of talus-slope, one of many rolled each year into the Gouge by exfoliation in the cliffs. Mike turned and smiled back at him gleefully, and he smiled back; the treads were clanking too loudly to permit any other answer.

The whole scheme had depended from the beginning upon so long a chain of ifs that it could still fall apart at any mo- ment and at any flawed link. It had been dependable only at the beginning. The signal Sweeacy had sent Meikiejon WANYhad told Meikiejon nothing, since he didn't know the code; but it had told the computer that Sweeney still lacked custody of the Adapted Men that Earth wanted, but that he had the help he thought he would need in getting that custody eventually. That much was a known. What orders the computer would rap out for Meikiejon in response com- prised the first of the ifs.

The computer might, of course, react with some incredibly bold piece of gamemanship too remote from normal human thinking to be even guessable; Shannon's chess-playing ma- chines sometimes won games from masters that way, though more usually they could barely hold their own against dubs.

Since there was no way to antic.i.p.ate what such a gambit would be like, neither Sweeney nor Rullman had wasted any time trying to pretend that there was.

But the other alternative was much more likely. The ma- chine would a.s.sume that Sweeney was safe, as was evidenced by the arrival of the coded signal; and that if he had help he could only have gathered about him a secret core of disaf- fected colonists, a "Loyal Ganymedian Underground" or equivalent. Earth would a.s.sume, and would build the a.s.sump- tion into the computer, that many of the colonists were dis- satisfied with their lives; it was a hope that Earth could turn into a fact without being aware of the delusion, since n.o.body on Earth could suspect how beautiful Ganymede was. And the computer would a.s.sume, too, that it might be only a mat- ter of time before Sweeney also had custody, and would be sending Meikiejon WAWYor maybe even YYAWY.

"How will we know if it does?" Rullman had demanded.

"If it does, then the deadline will pa.s.s without Meikiejon'a making a move. He'll just stick to his...o...b..t until the computer changes his mind. What else could it tell him to do, anyhow?

He's just one man in a small ship without heavy armament.

And he's an Earthman at thathe couldn't come down here and join my supposed underground group even if the idea oc- curred to him. He'll sit tight."

The halftrack heaved itself over an almost cubical boulder, slid sidewise along its tilted face, and dropped heavily to the bed of smaller rounded stones. Sweeney looked up from the radar controls to see how the big aluminum keg was taking the ride. It was awash in a sea of hand toolsrpicks, adzes, sledges, spikes, coils of line rapidly unwindingbut it was se- curely strapped down. The miracle of fireworks chemistry Cand .specifically, Ganymedian chemistry) still slumbered in- side it. He clambered forward into the cab beside Mike and strapped himself down to enjoy the ride.

There was no way to predict or to calculate how long an extension of the deadline the machine on Meikiejon's ship would allow Sweeney for the launching of his insurrection.

The colony worked as though there would be no grace period at all. When the deadline pa.s.sed without any sign that Meikie- jon even existedthough the radio-telescope showed that he was still thereSweeney and Rullman did not congratulate each other. They could not be sure that the silence and the delay meant what they had every good reason to hope that it meant. They could only go on working.

The movements of machines, men, and energy displays which should look to Meikiejon like a revolt of the colonists burst away from Howe's pi eleven days later. All the signs showed that it had been the loyalists who had set up their base near the north pole of Ganymede. Sweeney and Mike had driven through the Gouge before, for that purpose, plant- ing in a radar-crazy jungle a whole series of small devices, all automatic, all designed to register on Meikiejon's detectors as a vast bustle of heavy machinery. The visible stragetic move- ments of the opposing armies had suggested the same loyalist concentration at the pole.

And now Sweeney and Mike were on their way back.

The computer appeared to be v/aiting it out; Meikiejon had evidently fed the data to it as a real rebellion. Sweeney's side obviously was carrying the field-at first. The computer had no reason to run a new extrapolation up to the first day the loy- alist forces had managed to hold their lines; and then it had to run squarely up against the question of how. the loyalists could take the mountain even if, in the succeeding weeks, they should sweep the field clear of Sweeney.

"Kid stuff," Sweeney had said. "It hasn't any reason to think differently. Too simple to make it extrapolate beyond the first derivative."

"You're very confident, Donald."

Sweeney stirred uneasily in the bucket seat as he recalled RuUman's smile. No Adapted Man, least of all Sweeney, had had any real childhood; no "kid stuff." Fortunately the Port cops had thought it essential to Sweeney's task that he know theory of games.

The halftrack settled down to relatively smooth progress once more, and Sweeney got up to check the screen. The talus-slope, as Mike had antic.i.p.ated, cut off reception from the radar relay station behind them; Sweeney started the antenna sweeping. Much of the field was cropped by the near edge of the Gouge, but that effect would begin to disappear gradually from the screen now. The floor of the Gouge rose steadily as one approached the north pole, although it never quite reached the level of the plains. He could already capture enough sky to be satisfied that the Earth ships were just where they had been before.

That had been the last risk: that Meikiejon, alarmed at the computer's continued counsels of inaction, would radio Earth for advice from higher authorities. Obviously a colonists' re- volt on Ganymede, one that could be painted as a "We want to go home" movement, would be ideal for Earth's purposes.

Earth would not only insist on Meikiejon's sitting tight as his computer had told him to dobut would also hasten to bring up reinforcements for Sweeney, just in case.

Both Sweeney and RuUman had known how likely that was to happen, and had decided to take the chance, and make preparations against it. The chance had not paid offthe Earth ships were herebut it still looked as though the prep- arations might.

As content as was possible under the circ.u.mstances, Sweeney went forward. Before reaching for his safety belt, he stopped to kiss Mike, to the considerable detriment of her control of the lurching truck.

The explosion threw him, hard, halfway across the empty bucket seat.

He struggled up, his head ringing. The truck's engines seemed to have stopped; beneath the ringing, he could hear nothing but the sound of the blowers.

"Doni Are you all right? What was that?"

"Ugh," he said, sitting down. "Nothing broken. Hit my head a crack. It was high explosive, from the sound. A big one."

Her face was pinched and anxious in the soft glow from the dashboard. "One of ours? Or"

"I don't know, Mike. Sounded like it hit back down the ravine a distance.. What's the matter with the engine?"

She touched the starter. It whined, and the engine caught at once. "I must have stalled it," she said apologetically. She put it in gear. "But it doesn't feel right. The traction's bad on your side."

Sweeney swung the cab door open and dropped to the stony ground. Then he whistled.

"What is it?"

"That was closer than I thought," he called back. "The righthand track is cut almost in half. A flying rock splinter, I suppose. Toss me the torch."

She leaned far out across his seat, reaching the are-cutter to him, and then the goggles. He made his way to the rear of the truck and snapped the switch. The electric arc burned sulfur-blue; a moment later, the damaged track was unwind- ing from around the four big snowmobile tires like an ex- piring snake. Dragging the cord behind him, Sweeney cut the left track off, too, and then returned to the cab, rewinding the cord as he went.

"Okay, but take it slow. Those tires are going to be cut to ribbons by the time we hit that base."

Her face was still white, but she asked no more questions.

The halftrack began to crawl forward, a halftrack no longer.

At a little over two miles farther on, the first of the eight tires blew, making them both jump. A hasty check showed that it was the right outside rear one. Another two and a half miles, and the right inside drive tire blew out, too. It was bad to have two gone on the same side of the truck, but at least .they were on different axles and in alternate position. The next one to go, five miles farther onthe ground became less littered as it rosewas the left inside rear.

"Don."

"Yes, Mike."

"Do you think that was an Earth bomb?"

"I don't know, Mike. I doubt it; they're too far away to be throwing stuff at Ganymede except at random, and why would they do that? More likely it was one of our torpedoes, out of control." He snapped his fingers. "Wait a minute. If we're throwing H.E. at each other, now, the cops will have noticed, and that we can check."

Bang!

The halftrack settled down to the right and began to slob- ber at the ground. No check was needed to tell Sweeney that that one had been the right outside driver. Those two wheels would be hitting on bare rims within the next thousand feet or so of travel; the main weight of the vehicle was back there the steering tires took very little punishment, comparative- ly.

Gritting his teeth, he unbuckled the safety and scrambled back to the radar set, checking the aluminum drum auto- matically as he went.

There was much more sky showing on the screen now. It was impossible totriangulate the positions of the Earth ships now that the transmission from Howe's pi was cut off, but the pips on the screen were markedly dimmer. Sweeney guessed that they had retreated at least another hundred thousand miles. He grinned and leaned into Mike's ear.

"It was one of ours," he said. "Rullman's stepping up on the heavy artillery, that's all. One of his torpedo pilots must have lost one in the Gouge. The Port cops have detected the step-up, all rightthey've backed off. It's beginning to look more and more as though the rebels might try to smear the loyalist base with a fission bomb, and they don't want to be cheek to cheek with the planet "when that happens. How far do we have to go, still?"

Mikesaid,"We're"

Bang! Mike grabbed for the switch, and the engine died.

"here," she finished, and then, amazingly, began to gig- gle.

Sweeney swallowed, and then discovered that he was grin- ning, too. "With three track-tires intact," he said. "Hooray for us. Let's get on the job."

Another starsh.e.l.l broke open in the sky, not as near as be- fore. Sweeney went around to the back of the truck, Mike picking her way after him, both of them looking ruefully at the wreathes of shredded silicone rubber which once had been two excellent tires. Two of the rims were quite bare; the fifth deflated tire, which had not been driven on, was only a puncture and might be salvaged.

"Unstrap the barrel and roll 'er out the tailgate," Sweeney said. "Easy. Now let's lower 'er to the ground, and over there."

All around them, concealed among the rocks and the mas- sive, gnarled trunks, were the little instruments whose busy electronic chattering made this spot sound like a major mili- tary encampment to the ships lying off Ganymede. Photo- graphs, of course, would not be expected to show it: the visi- ble light was insufficient, the infra-red still weaker, and ultra- violet plates would be stopped by the atmosphere. n.o.body would expect to see anything from s.p.a.ce by any method, not in the Gouge; but the detectors would report power being ex- pended, and power sources moving aboutand rebel torpedoes homing purposefully on the area. That should be enough.

With Mike's help, Sweeney stood the aluminum barrel on end roughly in the center of this a.s.semblage. "I'm going to take that punctured tire off," he said. "We've got fifteen min- utes until take-off time, and we may need it later. Know how to wire up this thing?"

"I'm not an idiot. Go change your tire."

While Sweeney worked, Mike located the main input lead for the little invisible chatterers and spliced a line into it.

To this she rigged a spring-driven switch which would snap to "Off" as soon as current was delivered to a solenoid which actuated its trigger. One strand of reel-wound cable went to the solenoid, another to a red-splashed terminal on the side of the aluminum keg. She checked the thumb-plunger at the other end of the cable. Everything was ready. When that plunger was pushed, the little chatterers would go Off, at the same moment that the barrel went On.

"AH set, Mike?"

"Ready and waiting. Five minutes until take-off time."

"Good," Sweeney said, taking the reel from her. "You'd ~ better get in the truck and take it on across the poleover the horizon from here."