The image in the port stilled, and was that of the ringwall outlined against the stars.
A searchlight sprang up, began a methodical sweep across the floor of the crater, and they waited with interest for what it might show.
After a while, Keston said, "Sir, we've picked up a rocket in the shadow of the far ringwall. I have it on my screen."
Chang got up and came across the bridge to survey the harsh black and white image in front of Keston. The rocket was a small one, perhaps even an individual job, and its hull shone unblink-ingly in the glare of the searchlight.
"Locks wide, you notice," commented Chang after a while. "Looks like it got left behind when they quit. Put the building on the screen, will you?"
The screen flickered and then went blank except for the jagged line of the ringwall silhouetted against the stars. It was a matter of two or three seconds before the searchlight swept around and showed a tall building, tall with the fantastic flying tallness of low gravity, that looked like the main hall at Grand Central Spaceport made aesthetically acceptable. You could have put the ship inside it with no trouble at all.
Chang studied it with considerable interest. It was plainly the work of a race versed in architecture, for it was superbly designed to waste no more than necessary on resisting gravity, yet to maintain an atmosphere at fourteen pounds to the square inch without risk.
But it was open and deserted.
They stood looking at it in silence, except for the very quiet humming of the generators and the creak-crack of the hull that was the ship talking to itself. Finally Chang straightened with a grunt.
"Engelhart!"
"Sir?"
"Are your men standing to battle stations?"
"Of course, sir," said Engelhart with injured dignity.
"They needn't. There won't be a reception committee. But detail me a couple of men to come on over and take a gander at this place before we go downstairs, will you? You can come yourself if you like."
"Glad to, sir," said Engelhart. "What do I tell the men we've got?"
"Looks like a plum cake, but tell them not to count their chickens. Say we've struck an Earth-type world which looks like it's uninhabited, but emphasize that bit about the looking."
"Good enough, sir. When do we start?"
"As soon as you're ready," said Chang. He knocked out his pipe and went towards the door, paused before going out to look at the scene in the viewport. So many stars, and no knowing what you'd find among them—
He went down to Medical and submitted to having his semicircular canals numbed to prevent nausea and his heart slowed to avoid wasting energy. Then two orderlies helped him into his bulky spacesuit, and he shuffled awkwardly out of the hospital section into the anteroom of the personnel lock.
There was only moon gravity here—about one-tenth g—and he flexed his arms and legs a few times and checked his equipment. Before he finished Engelhart joined him, face keen and sharp behind his transparent mask. He nodded, clicked on his microphone and said, "Can you hear me, sir?"
"Loud and clear. Who've you picked to come with us?"
"Trooper Anson, sir. He'll be here in a moment." He checked his oxygen supply with practiced efficiency, turned his torch on and off a few times, and stamped to make sure his joints were working freely.
Then Trooper Anson joined them, and they moved cautiously into the lock and waited while the big doors behind them slid shut. Before the others opened, a voice crackled in their phones.
"Keston here, sir. We're keeping our 'scopes on you just in case, but I don't expect you'll find trouble. We found one hole in the top of the building twenty feet across."
Chang said, "Right. Stand by to open locks. Ready?"
"Ready."
They turned on their magnetic soles for the brief instant in which the air in the lock whooshed out into free space with a thin scream, and then they moved forward to the top of the ramp beyond and stood staring at a monument to a vanished race.
The stars filled the sky so brightly that they had to shade their eyes to see it in the dim glow of the searchlight—a vast and empty, and enigmatic, building.
Chang said slowly, "That's a lovely piece of design, Engel-hart."
Engelhart nodded behind his faceplate. "They never knocked that up on their first trip. I'd lay good money on there being a city under here. I wonder why they abandoned it."
Chang shrugged. "We'll find out later—perhaps. Shall we move?"
They went down the metal ramp to the scorched rock at its foot, snapped off their magnetic soles and began to bound in twenty-foot leaps across the short mile that separated them from the building.
For a while there was no noise except star static and the irregular thud after each jump as they landed with enough force to disturb the microphones, and they braked gradually to a halt a few yards from the open end of the building.
They stood surveying it. After a pause, Chang said, "Anson!"
"Sir?"
"Shine your torch inside, will you?"
A few seconds later a puddle of dazzling light a few inches in diameter sprang up on the ground before them and leaped into the cavernous hollow, widening as it did so. It showed nothing.
Chang said, "Switch it off," and took the shade away from his faceplate.
After a while he could make out a little of the interior by the starlight that filtered through a dozen gashes in the vaulting roof. The main floor of the hall was smooth and level, but stacked at the sides were crates, their metal bright and untarnished in the airlessness, and a small vehicle stood parked against one wall.
Far at the back he could dimly discern something like an elevator shaft leading down into the crust of the moon—presumably the city of which this was the outward and visible sign.
He said, "Keston, still watching us?"
"Of course, sir," Keston answered from the ship.
"We're going inside. Your 'scopes'U lose us and I imagine radar will, too. These walls are metal. I'll have Anson stay here, though, and we'll relay messages through him. Got that?"
"Right, sir," said Keston.
Anson had already taken his orders and moved off to one side. He was unfolding the chair attachment of his suit as Chang and Engelhart took their first cautious steps into the building, their torches shedding small circles of light that dimmed to nothing a hundred feet away.
The floor, Chang noted, was metal, smooth and unmarked save for a few bright scratches. He heard a thud then, both through his earphones and by bone-conduction from the floor. He turned in astonishment to see Engelhart making determined but fruitless efforts to lift his feet from the floor.
Engelhart cut short his startled exclamation. He said in a queer voice, "I just switched on my magnets to see if the floor was magnetic, sir. Take a look at it, will you?"
Chang nodded and bent down, examining it. It was cobalt blue and magnetic, and the durasteel knife built into his right glove blunted its tip against it. He looked up and said in an awed voice, "That's durasteel, Engelhart."
"Yes, sir. I thought so. And any race that can afford to throw it around like this has my respect."
Chang got up slowly. "Mine too, Engelhart," he said. "This place just couldn't be duplicated by man. Why, any single planet wouldn't have enough durasteel to floor it. They got a long way ahead of us, then. I wonder why they went."
Engelhart shrugged, and they went over to inspect the crates piled up at the side, but they were empty, or contained no more than the flotsam left by a swiftly ebbing tide of civilization—so much so, that one would have sworn the users of the hammers and drill atop the open crates had just put them down and would be back in a moment. The small vehicle afforded no clues. It was apparently self-propelled, but there was no visible power source, unless it absorbed induced electricity from the floor, or broadcast energy; the controls, which might have helped them to picture the creature who used them, had been pared down to a single rod bearing a simple press-button on the tip that served for bo
th steering and start-stop gear, and there was no rest or seat.
Chang grunted, said, "That tells us a lot!"
Engelhart said, "Sir, I think if there is anything to be found here at all, it'll be in the city beneath, and that may call for a full-scale investigation. Chances are it'd be simpler to study the planet itself. If they've had space travel and lost it, even if they haven't died off altogether, they won't present any serious problem."
"Agreed. But we'd best have a look at the entry to the city beneath at least before we move on." Chang swept his torch-beam around and froze suddenly, his free hand groping wildly for the blaster at his side. Engelhart caught his muttered exclamation, followed his eye and almost cried out in horror.
Then Chang relaxed, chuckling. "Phew, that gave me a fright! I thought for a moment we'd run across an alien, but it's only a robot. I wonder how long it's been here."
Engelhart wiped his forehead a little shakily against the absorbent lining of his helmet, and said with heartfelt relief, "Let's go take a look at it, sir."
Together they leaped across the intervening forty-odd yards and halted to survey the immobile robot. It was not purely uniform, but like many human-built servitors a rough imitation of its creators. It was about nine feet tall and faintly anthropoid in that it had a head, topping a cylindrical body, but it had six limbs—two legs, four arms ending in delicate plierlike devices with cutting, shaping and gripping appliances. Two lenses in the front of its head, set close together, shone dully in the light of their torches.
"Will you want this taken back to the ship?" Engelhart asked.
"No, that can wait. It's been here space knows how long already. It won't run away, and another few days waiting won't hurt it. There are more urgent things to do."
With a lingering backward glance at the motionless machine, Engelhart turned to follow the captain into the back of the hall, towards the downward-leading shafts. They also had locks, as a precaution against meteor-damage to the outer section, but at both ends they were fully open, and there was no air below.
Chang shuddered slightly as he looked down five hundred feet into their black depths. He said, "I wouldn't have liked to be down there when the first meteor hit."
Engelhart said, "I don't think there was anyone there then, sir. It looks to me as if they simply checked out in a big hurry— they wouldn't have left the outer locks open otherwise."
"That's a point," agreed Chang. "So there wouldn't be much below even if we did try to climb in. I think you were right about the advisability of moving downstairs right away. Let's go."
Engelhart was shining his torch down the shaft without result. He said, "I notice they did economize on the durasteel as far as lining the shaft goes. This floor's only about six inches thick, but even so it's a pretty costly extravagance—"
Chang turned sharply and stared back towards the entrance where Trooper Anson was visible waiting patiently in radio view of the ship.
"What is it, sir?" Engelhart demanded.
Chang gestured with his torch, and the other automatically followed an extension of his line of motion up to the jagged rents in the roof. He said, "See that big gash? How big a meteor do you imagine it would take to make it?"
Engelhart calculated rapidly. "I'd say it couldn't have been less than twenty feet across, which means—eleven, twelve—a mass of maybe a hundred tons."
Chang began to move out across the floor, switching his torch from side to side as he went. He said, "Since when has six inches even of durasteel been able to take a kick like that? Can you see any signs of meteor fragments or splash damage? Ah, here we are. Look—the floor's been re-welded and ground smooth with a high velocity diamond buffer to make it level. And it's just below the biggest meteor strike."
Engelhart, glancing up at the thick-packed stars beyond the shattered roof, said, "That's very strange, sir."
Chang was following the marks of the weld around the floor. He said, half to himself, "Who repaired this floor? And why didn't they fix the roof first to give themselves air to work in?"
"Maybe they used robots for the job," suggested Engelhart. "That would account for the presence of the one we saw."
"Could do," said Chang, straightening up. "But then why didn't they finish the job? What made them stop halfway? And will it do the same to us? Out of here, Engelhartl Jump!"
Three quarters of an hour later he stood gazing from the viewport in the nose of the ship while they lifted away from the moon and began the leisurely topple into an orbit that would brush atmosphere and allow them to settle without any fuss, letting the air do their braking for them.
Behind him Keston said suddenly, "Sir, Hardesty says he just picked up a flicker from astem. It's gone into radar shadow now, but he says it didn't look like a meteor—could have been a ship."
"Big or small?"
"Small, sir. About the size of the rocket we found back on the moon."
"Then it probably was that," said Chang, turning quickly. "Deeley, Spinelli, give us a quick put-down."
"Do you mean really quick or just quick, sir?" asked Spinelli. Deeley's hands leaped for the Nav computer before him.
"Really quick. A bottlestopper. Pick the largest piece of open-wide open—flat ground you can in the time. Engelhart!"
Engelhart said without looking round from his control desk, "Sir?"
"Get the men to battle stations again, just in case." Engelhart nodded, pushed the red knob at the top left of his board. A bell sounded faintly somewhere inship.
"Sir!"
"Yes, Spinelli?"
"Bottlestopper coming up, sir. Well be down in about thirty seconds from—NOW!"
Twenty-nine seconds later the ship, red-hot from her whirlwind swoop through the atmosphere, fired half a square mile of grasslike plants in the approximate middle of a smoothly rolling plain dotted with clumps of trees at intervals of about a mile. Engelhart, whose responsibility it was, ordered out the extinguisher sprays, and when the mist of their operation blew clear of the viewport Chang looked out on a blue sky a little darker than that of his own planet and a sun a little yellower than the one under which he had grown up. But the vegetation was green and waved in the breeze like grass, and faintly on the horizon showed low blue mountains. He said almost absently, "Deeley, this is a splendid world."
"Thank you, sir," said Deeley. He had deduced the existence of it from a distance of ninety light-years and brought them out of hyperspace within half a million miles of it—which was a remarkable piece of navigation—so there was reason for congratulation.
Engelhart said, "What are we supposed to do, sir?"
"Sit around, as usual, Engelhart—what else? We can't be sure it was a ship Hardesty picked up, but if it was and if it was the one we saw on the moon, then it can only be the robot on board."
They digested that in silence.
"In which case we can assume that the inhabitants will pay us a call, and soon. Maybe we were wrong in assuming that because the dome on the moon was broken they'd had space travel and lost it. Maybe it's only temporarily out of commission while robots see to the damage, not completely abandoned."
Keston said dryly, "Then where are the inhabitants hiding, sir?"
Chang shrugged. He said, "This is an old world, Keston. The race inhabiting it could be a whole lot ahead of us. Maybe they don't build cities or roads. Maybe they live in isolated houses and fly everywhere. Keep your men to stations, Engelhart. Adhem!"
"Sir?" said the medical officer.
"While we're waiting, you can run off the usual tests—presence of viruses, bacteria, and injurious ingredients in the air and ground, and so on."
"Right away, sir."
They waited. It was unlikely that there were any natives within quite a few miles, at any rate. They had seen, as they came down, no roads, no cities, no spaceports, and no sign of any smaller artificial construction. True, they had had almost no time to look for them. They had come through one hundred ninety miles of detectable atmosphere
in twenty-nine seconds, and even the so-called instantaneous cameras couldn't hold focus at that speed. But this nearly flat and mostly bare plain seemed natural and haphazard enough, without sign of planned layout, and if it was big enough for Spinelli to have picked it out from a hundred thousand miles out—
Adhem's speaker burped and whispered for a moment, and after a few curt comments the medical officer said helplessly, "All right then." He turned to Chang.
"I can give this place a clean bill of health, sir," he said. His voice held a disapproving note.
Chang observed it, commented, "Something's eating you."
"Yes, sir. There is not one single bacterium, virus or subvirus in any of the air, soil or vegetation samples we took. There is no sign of any poison, either, but that doesn't worry us. But it isn't natural for there to be no bacterial"
"Perhaps it isn't natural," said Chang equably. "After all, the only bacteria aboard this ship are the ones we use to digest our food, but that isn't natural. We saw to it ourselves."
"But you couldn't do that to a whole world—I"
"Why not? I'd believe a lot of a race that can afford to floor the supply lock of a complete city with durasteel. Either way, what does it matter? Engelhart!"
"Sir?"
"I want a thorough survey of the immediate neighborhood from as low as your boys can go without getting into trouble. Say within a radius of a hundred miles. That's your pigeon. Use helis, and screen them well. Deeley, I also want a full photographic record with wide-angle and instantaneous cameras and full color stereo prints of the entire surface of the planet—land and water—from high level. You can have two of the lifeboats for that. And I want results quicker than jump. Engelhart—one more thing: Tell your boys to pay special attention to anything that could be a sign of habitation and report it as soon as found."
"Right, sir," said Engelhart, and he and Deeley turned to their control desks, whispering orders into hanging microphones.
Chang turned to Adhem, said, "Is this planet safe?"