"Levine didn't make it," Barnes said briskly. "He got claustrophobic in the sub coming down, and had to be taken back. One of those things."

"Then we have no marine biologist?"

"We'll manage without him."

"I hate this damn jumpsuit," Ted said. "I really hate it."

"Beth looks good in hers."

"Yes, Beth works out."

"And it's damp in here, too," Ted said. "Is it always so damp?"

Norman had noticed that humidity was a problem; everything they touched felt slightly wet and clammy and cold. Barnes warned them of the danger of infections and minor colds, and handed out bottles of skin lotion and ear drops.

"I thought you said the technology was all worked out," Harry said.

"It is," Barnes said. "Believe me, this is plush compared to the habitats ten years ago."

"Ten years ago," Harry said, "they stopped making habitats because people kept dying in them."

Barnes frowned. "There was one accident."

"There were two accidents," Harry said. "A total of four people."

"Special circumstances," Barnes said. "Not involving Navy technology or personnel."

"Great," Harry said. "How long did you say we going to be down here?"

"Maximum, seventy-two hours," Barnes said.

"You sure about that?"

"It's Navy regs," Barnes said.

"Why?" Norman asked, puzzled.

Barnes shook his head. "Never," he said, "never ask a reason for Navy regulations."

The intercom clicked, and Tina Chan said, "Captain Barnes, we have a signal from the divers. They are mounting the airlock now. Another few minutes to open."

The feeling in the room changed immediately; the excitement was palpable. Ted rubbed his hands together. "You realize, of course, that even without opening that spacecraft, we have already made a major discovery of profound importance."

"What's that?" Norman said.

"We've shot the unique event hypothesis to hell," Ted said, glancing at Beth.

"The unique event hypothesis?" Barnes said.

"He's referring," Beth said, "to the fact that physicists and chemists tend to believe in intelligent extraterrestrial life, while biologists tend not to. Many biologists feel the development of intelligent life on Earth required so many peculiar steps that it represents a unique event in the universe, that may never have occurred elsewhere."

"Wouldn't intelligence arise again and again?" Barnes said.

"Well, it barely arose on the Earth," Beth said. "The Earth is 4.5 billion years old, and single-celled life appeared 3.9 billion years ago - almost immediately, geologically speaking. But life remained single-celled for the next three billion years. Then in the Cambrian period, around six hundred million years ago, there was an explosion of sophisticated life forms. Within a hundred million years, the ocean was full of fish. Then the land became populated: Then the air. But nobody knows why the explosion occurred in the first place. And since it didn't occur for three billion years, there's the possibility that on some other planet, it might never occur at all.

"And even after the Cambrian, the chain of events leading to man appears to be so special, so chancy, that biologists worry it might never have happened. Just consider the fact that if the dinosaurs hadn't been wiped out sixty-five million years ago - by a comet or whatever - then reptiles might still be the dominant form on Earth, and mammals would never have had a chance to take over. No mammals, no primates. No primates, no apes. No apes, no man ... There are a lot of random factors in evolution, a lot of luck. That's why biologists think intelligent life might be a unique event in the universe, only occurring here."

"Except now," Ted said, "we know it's not a unique event. Because there is a damn big spacecraft out there."

"Personally," Beth said, "I couldn't be more pleased." She bit her lip.

"You don't look pleased," Norman said.

"I'll tell you," Beth said. "I can't help being nervous. Ten years ago, Bill Jackson at Stanford ran a series of weekend seminars on extraterrestrial life. This was right after he won the Nobel prize in chemistry. He split us into two groups. One group designed the alien life form, and worked it all out scientifically. The other group tried to figure out the life form, and communicate with it. Jackson presided over the whole thing as a hard scientist, not letting anybody get carried away. One time we brought in a sketch of a proposed creature and he said, very tough, 'Okay, where's the anus?' That was his criticism. But many animals on Earth have no anus. There are all kinds of excretory mechanisms that don't require a special orifice. Jackson assumed an anus was necessary, but it isn't. And now ..." She shrugged. "Who knows what we'll find?"

"We'll know, soon enough," Ted said.

The intercom clicked. "Captain Barnes, the divers have the airlock mounted in place. The robot is now ready to enter the spacecraft."

Ted said, "What robot?"

THE DOOR

"I don't think it's appropriate at all," Ted said angrily. "We came down here to make a manned entry into this alien spacecraft. I think we should do what we came here to do - make a manned entry."

"Absolutely not," Barnes said. "We can't risk it."

"You must think of this," Ted said, "as an archaeological site. Greater than Chichen Itz��, greater than Troy, greater than Tutankhamen's tomb. Unquestionably the most important archaeological site in the history of mankind. Do you really intend to have a damned robot open that site? Where's your sense of human destiny?"

"Where's your sense of self-preservation?" Barnes said.

"I strongly object, Captain Barnes."

"Duly noted," Barnes said, turning away. "Now let's get on with it. Tina, give us the video feed."

Ted sputtered, but he fell silent as two large monitors in front of them clicked on. On the left screen, they saw the complex tubular metal scaffolding of the robot, with exposed motors and gears. The robot was positioned before the curved gray metal wall of the spacecraft.

Within that wall was a door that looked rather like an airliner door. The second screen gave a closer view of the door, taken by the video camera mounted on the robot itself. "It's rather similar to an airplane door," Ted said.

Norman glanced at Harry, who smiled enigmatically. Then he looked at Barnes. Barnes did not appear surprised. Barnes already knew about the door, he realized.

"I wonder how we can account for such parallelism in door design," Ted said. "The likelihood of its occurring by chance is astronomically small. Why, this door is the perfect size and shape for a human being!"

"That's right," Harry said.

"It's incredible," Ted said. "Quite incredible." Harry smiled, said nothing.

Barnes said, "Let's find control surfaces."

The robot video scanner moved left and right across the spacecraft hull. It stopped on the image of a rectangular panel mounted to the left of the door.

"Can you open that panel?"

"Working on it now, sir."

Whirring, the robot claw extended out toward the panel. But the claw was clumsy; it scraped against the metal, leaving a series of gleaming scratches. But the panel remained closed.

"Ridiculous," Ted said. "It's like watching a baby."

The claw continued to scratch at the panel.

"We should be doing this ourselves," Ted said.

"Use suction," Barnes said.

Another arm extended out, with a rubber sucker. "Ah, the plumber's friend," Ted said disdainfully.

As they watched, the sucker attached to the panel, flattened. Then, with a click, the panel lifted open.

"At last!"

"I can't see. ..."

The view inside the panel was blurred, out of focus. They could distinguish what appeared to be a series of colored round metal protrusions, red, yellow, and blue. There were also intricate black-and-white symbols above the knobs.

"Look," Ted said, "red, blue, yellow. Primary colors. This is a very big break."

"Why?" Norman said.

"Because it suggests that the aliens have the same sensory equipment that we do - they may see the universe the same way, visually, in the same colors, utilizing the same part of the electromagnetic spectrum. That's going to help immeasurably in making contact with them. And those black-and-white markings ... that must be some of their writing! Can you imagine! Alien writing!" He smiled enthusiastically. "This is a great moment," he said. "I feel truly privileged to be here."

"Focus," Barnes called. "Focusing now, sir."

The image became even more blurred. "No, the other way."

"Yes Sir. Focusing now."

The image changed, slowly resolved into sharp focus. "Uh-oh," Ted said, staring at the screen.

They now saw that the blurred knobs were actually three colored buttons: yellow, red, and blue. The buttons were each an inch in diameter and had knurled or machined edges. The symbols above the buttons resolved sharply into a series of neatly stenciled labels.

From left to right the labels read: "Emergency Ready," "Emergency Lock," and "Emergency Open."

In English.

There was a moment of stunned silence. And then, very softly, Harry Adams began to laugh.

THE SPACECRAFT

"That's English," Ted said, staring at the screen. "Written English."

"Yeah," Harry said. "Sure is."

"What's going on?" Ted said. "Is this some kind of joke?"

"No," Harry said. He was calm, oddly detached.

"How could this spacecraft be three hundred years old, and carry instructions in modem English?"

"Think about it," Harry said.

Ted frowned. "Maybe," he said, "this alien spacecraft is somehow presenting itself to us in a way that will make us comfortable."

"Think about it some more," Harry said.

There was a short silence. "Well, if it is an alien spacecraft - "

"It's not an alien spacecraft," Harry said.

There was another silence. Then Ted said, "Well, why don't you just tell us all what it is, since you're so sure of yourself!"

"All right," Harry said. "It's an American spacecraft."

"An American spacecraft? Half a mile long? Made with technology we don't have yet? And buried for three hundred years?"

"Of course," Harry said. "It's been obvious from the start. Right, Captain Barnes?"

"We had considered it," Barnes admitted. "The President had considered it."

"That's why you didn't inform the Russians."

"Exactly."

By now Ted was completely frustrated. He clenched his fists, as if he wanted to hit someone. He looked from one person to another. "But how did you know?"

"The first clue," Harry said, "came from the condition of the craft itself. It shows no damage whatever. Its condition is pristine. Yet any spacecraft that crashes in water will be damaged. Even at low entry velocities - say two hundred miles an hour - the surface of water is as hard as concrete. No matter how strong this craft is, you would expect some degree of damage from the impact with the water. Yet it has no damage."

"Meaning?"

"Meaning it didn't land in the water."

"I don't understand. It must have flown here - "

" - It didn't fly here. It arrived here."

"From where?"

"From the future," Harry said. "This is some kind of Earth craft that was - will be - made in the future, and has traveled backward in time, and appeared under our ocean, several hundred years ago."

"Why would people in the future do that?" Ted groaned. He was clearly unhappy to be deprived of his alien craft, his great historical moment. He slumped in a chair and stared dully at the monitor screens.

"I don't know why people in the future would do that," Harry said. "We're not there yet. Maybe it was an accident. Unintended."

"Let's go ahead and open it up," Barnes said.

"Opening, sir."

The robot hand moved forward, toward the "Open" button. The hand pressed several times. There was a clanking sound, but nothing happened.

"What's wrong?" Barnes said.

"Sir, we're not able to impact the button. The extensor arm is too large to fit inside the panel."

"Great."

"Shall I try the probe?"

"Try the probe."

The claw hand moved back, and a thin needle probe extended out toward the button. The probe slid forward, adjusted position delicately, touched the button. It pushed - and slipped off.

"Trying again, sir."

The probe again pressed the button, and again slid off.

"Sir, the surface is too slippery."

"Keep trying."

"You know," Ted said thoughtfully, "this is still a remarkable situation. In one sense, it's even more remarkable than contact with extraterrestrials. I was already quite certain that extraterrestrial life exists in the universe. But time travel! Frankly, as an astrophysicist I had my doubts. From everything we know, it's impossible, contradicted by the laws of physics. And yet now we have proof that time travel is possible - and that our own species will do it in the future!"

Ted was smiling, wide-eyed, and happy again. You had to admire him, Norman thought - he was so wonderfully irrepressible.

"And here we are," Ted said, "on the threshold of our first contact with our species from the future! Think of it! We are going to meet ourselves from some future time!"

The probe pressed again, and again, without success.

"Sir, we cannot impact the button."

"I see that," Barnes said, standing up. "Okay, shut it down and get it out of there. Ted, looks like you're going to get your wish after all. We'll have to go in and open it up manually. Let's suit up."

INTO THE SHIP

In the changing room in cylinder A, Norman stepped into his suit. Tina and Edmunds helped fit the helmet over his head, and snap-locked the ring at the neck. He felt the heavy weight of the rebreather tanks on his back; the straps pressed into his shoulders. He tasted metallic air. There was a crackle as his helmet intercom came on.

The first words he heard were "What about 'At the threshold of a great opportunity for the human species'?" Norman laughed, grateful for the break in the tension.

"You find it funny?" Ted asked, offended.

Norman looked across the room at the suited man with "FIELDING" stenciled on his yellow helmet.

"No," Norman said. "I'm just nervous."

"Me, too," Beth said.

"Nothing to it," Barnes said.

"Trust me."

"What are the three biggest lies in DH-8?" Harry said, and they laughed again.

They crowded together into the tiny airlock, bumping helmeted heads, and the bulkhead hatch to the left was sealed, the wheel spinning. Barnes said, "Okay, folks, just breathe easy." He opened the lower hatch, exposing black water. The water did not rise into the compartment. "The habitat's on positive pressure," Barnes said. "The level won't come up. Now watch me, and do this the way I do. You don't want to tear your suit." Moving awkwardly with the weight of the tanks, he crouched down by the hatch, gripped the side handholds, and let go, disappearing with a soft splash.

One by one, they dropped down to the floor of the ocean. Norman gasped as near-freezing water enveloped his suit; immediately he heard the hum of a tiny fan as the electrical heaters in his suit activated. His feet touched soft muddy ground. He looked around in the darkness. He was standing beneath the habitat. Directly ahead, a hundred yards away, was the glowing rectangular grid. Barnes was already striding forward, leaning into the current, moving slowly like a man on the moon.

"Isn't this fantastic?"

"Calm down, Ted," Harry said.

Beth said, "Actually, it's odd how little life there is down here. Have you noticed? Not a sea fan, not a slug, not a sponge, not a solitary fish. Nothing but empty brown sea floor. This must be one of those dead spots in the Pacific."

A bright light came on behind him; Norman's own shadow was cast forward on the bottom. He looked back and saw Edmunds holding a camera and light in a bulky waterproof housing.

"We recording all this?"

"Yes, sir."

"Try not to fall down, Norman," Beth laughed.

"I'm trying."

They were closer now to the grid. Norman felt better seeing the other divers working there. To the right was the high fin, extending out of the coral, an enormous, smooth dark surface dwarfing them as it rose toward the surface.

Barnes led them past the fin and down into a tunnel cut in the coral. The tunnel was sixty feet long, narrow, strung with lights. They walked single file. It felt like going down into a mine, Norman thought.

"This what the divers cut?"

"That's right."

Norman saw a boxy, corrugated-steel structure surrounded by pressure tanks.

"Airlock ahead. We're almost there," Barnes said. "Everybody okay?"

"So far," Harry said.

They entered the airlock, and Barnes closed the door. Air hissed loudly. Norman watched the water recede, down past his faceplate, then his waist, his knees; then to the floor. The hissing stopped, and they passed through another door, sealing it behind them.

Norman turned to the metal hull of the spaceship. The robot had been moved aside. Norman felt very much as if he were standing alongside a big jetliner - a curved metal surface, and a flush door. The metal was a dull gray, which gave it an ominous quality. Despite himself, Norman was nervous. Listening to the way the others were breathing, he sensed they were nervous, too.

"Okay?" Barnes said. "Everybody here?"

Edmunds said, "Wait for video, please, sir."

"Okay. Waiting."

They all lined up beside the door, but they still had their helmets on. It wasn't going to be much of a picture, Norman thought.

Edmunds: "Tape is running."

Ted: "I'd like to say a few words."

Harry: "Jesus, Ted. Can't you ever let up?"

Ted: "I think it's important."

Harry: "Go ahead, make your speech."

Ted: "Hello. This is Ted Fielding, here at the door of the unknown spacecraft which has been discovered - "

Barnes: "Wait a minute, Ted. 'Here at the door of the unknown spacecraft' sounds like 'here at the tomb of the unknown soldier.' "

Ted: "You don't like it?"

Barnes: "Well, I think it has the wrong associations."

Ted: "I thought you would like it."

Beth: "Can we just get on with it, please?"

Ted: "Never mind."

Harry: "What, are you going to pout now?"

Ted: "Never mind. We'll do without any commentary on this historic moment."

Harry: "Okay, fine. Let's get it open."

Ted: "I think everybody knows how I feel. I feel that we should have some brief remarks for posterity."

Harry: "Well, make your goddamn remarks!"

Ted: "Listen, you son of a bitch, I've had about enough of your superior, know-it-all attitude - "

Barnes: "Stop tape, please."

Edmunds: "Tape is stopped, sir."

Barnes: "Let's everyone settle down."

Harry: "I consider all this ceremony utterly irrelevant."

Ted: "Well, it's not irrelevant; it's appropriate."

Barnes: "All right, I'll do it. Roll the tape."

Edmunds: "Tape is rolling."

Barnes: "This is Captain Barnes. We are now about to open the hatch cover. Present with me on this historic occasion are Ted Fielding, Norman Johnson, Beth Halpern, and Harry Adams."

Harry: "Why am I last?"

Barnes: "I did it left to right, Harry."

Harry: "Isn't it funny the only black man is named last?"

Barnes: "Harry, it's left to right. The way we're standing here."

Harry: "And after the only woman. I'm a full professor, Beth is only an assistant professor."

Beth: "Harry - "

Ted: "You know, Hal, perhaps we should be identified by our full titles and institutional affiliations - "

Harry: " - What's wrong with alphabetical order - "

Barnes: " - That's it! Forget it! No tape!"

Edmunds: "Tape is off, sir."

Barnes: "Jesus Christ."

He turned away from the group, shaking his helmeted head. He flipped up the metal plate, exposed the two buttons, and pushed one. A yellow light blinked "READY."

"Everybody stay on internal air," Barnes said.

They all continued to breathe from their tanks, in case the interior gases in the spacecraft were toxic.

"Everybody ready?"

"Ready."

Barnes pushed the button marked "OPEN."

A sign flashed: ADJUSTING ATMOSPHERE. Then, with a rumble, the door slid open sideways, just like an airplane door. For a moment Norman could see nothing but blackness beyond. They moved forward cautiously, shone their lights through the open door, saw girders, a complex of metal tubes.

"Check the air, Beth."

Beth pulled the plunger on a small gas monitor in her hand. The readout screen glowed.

"Helium, oxygen, trace CO2 and water vapor. The right proportions. It's pressurized atmosphere."

"The ship adjusted its own atmosphere?"

"Looks like it."

"Okay. One at a time."

Barnes removed his helmet first, breathed the air. "It seems okay. Metallic, a slight tingle, but okay." He took a few deep breaths, then nodded. The others removed their helmets, set them on the deck.

"That's better."

"Shall we go?"

"Why not?"

There was a brief hesitation, and then Beth stepped through quickly: "Ladies first."

The others followed her. Norman glanced back, saw all their yellow helmets lying on the floor. Edmunds, holding the video camera to her eye, said, "Go ahead, Dr. Johnson." Norman turned, and stepped into the spacecraft.

INTERIOR

They stood on a catwalk five feet wide, suspended high in the air. Norman shone his flashlight down: the beam glowed through forty feet of darkness before it splashed on the lower hull. Surrounding them, dimly visible in the darkness, was a dense network of struts and girders.

Beth said, "It's like being in an oil refinery." She shone her light on one steel beam. Stenciled was "AVR-09." All the stenciling was in English.

"Most of what you see is structural," Barnes said. "Cross-stress bracing for the outer hull. Gives tremendous support along all axes. The ship is very ruggedly built, as we suspected. Designed to take extraordinary stresses. There's probably another hull further in." Norman was reminded that Barnes had once been an aeronautical engineer.

"Not only that," Harry said, shining his light on the outer hull. "Look at this - a layer of lead."

"Radiation shield?"

"Must be. It's six inches thick."

"So this ship was built to handle a lot of radiation."

"A hell of a lot," Harry said.

There was a haze in the ship, and a faintly oily feel to the air. The metal girders seemed to be coated in oil, but when Norman touched them, the oil didn't come off on his fingers. He realized that the metal itself had an unusual texture: it was slick and slightly soft to the touch, almost rubbery.

"Interesting," Ted said. "Some kind of new material. We associate strength with hardness, but this metal - if it is metal - is both strong and soft. Materials technology has obviously advanced since our day."

"Obviously," Harry said.

"Well, it makes sense," Ted said. "If you think of America fifty years ago as compared with today, one of the biggest changes is the great variety of plastics and ceramics we have now that were not even imagined back then. ..." Ted continued to talk, his voice echoing in the cavernous darkness. But Norman could hear the tension in his voice. Ted's whistling in the dark, he thought.

They moved deeper into the ship. Norman felt dizzy to be so high in the gloom. They came to a branchpoint in the catwalk. It was hard to see with all the pipes and struts - like being in a forest of metal.

"Which way?"

Barnes had a wrist compass; it glowed green. "Go right." They followed the network of catwalks for ten minutes more. Gradually Norman could see that Barnes was right: there was a central cylinder constructed within the outer cylinder, and held away from it by a dense arrangement of girders and supports. A spacecraft within a spacecraft.

"Why would they build the ship like this?"

"You'd have to ask them."

"The reasons must have been compelling," Barnes said. "The power requirements for a double hull, with so much lead shielding ... hard to imagine the engine you'd need to make something this big fly."

After three or four minutes, they arrived at the door on the inner hull. It looked like the outer door.

"Breathers back on?"

"I don't know. Can we risk it?"

Without waiting, Beth flipped up the panel of buttons, pressed "OPEN," and the door rumbled open. More darkness beyond. They stepped through. Norman felt softness underfoot; he shined his light down on beige carpeting.

Their flashlights crisscrossed the room, revealing a large, contoured beige console with three high-backed, padded seats. The room was clearly built for human beings.

"Must be the bridge or the cockpit."

But the curved consoles were completely blank. There was no instrumentation of any kind. And the seats were empty. They swung their beams back and forth in the darkness. "Looks like a mockup, rather than the real thing."

"It can't be a mockup."

"Well, it looks like one."

Norman ran his hand over the smooth contours of the console. It was nicely molded, pleasant to feel. Norman pressed the surface, felt it bend to his touch. Rubbery again. "Another new material."

Norman's flashlight showed a few artifacts. Taped to the far end of the console was a handmarked sign on a three-by-five filing card: It said, "GO BABY GO!" Nearby was a small plastic statuette of a cute animal that looked like a purple squirrel. The base said, "Lucky Lemontina." Whatever that meant.

"These seats leather?"

"Looks like it."

"Where are the damned controls?"

Norman continued to poke at the blank console, and suddenly the beige console surface took on depth, and appeared to contain instruments, screens. All the instrumentation was somehow within the surface of the console, like an optical illusion, or a hologram. Norman read the lettering above the instruments: "Pos Thrusters" ... "F3 Piston Booster" ... "Glider" ... "Sieves" ...

"More new technology," Ted said. "Reminiscent of liquid crystals, but far superior. Some kind of advanced optoelectronics."

Suddenly all the console screens glowed red, and there was a beeping sound. Startled, Norman jumped back; the control panel was coming to life.

"Watch it, everybody!"

A single bright lightning flash of intense white light filled the room, leaving a harsh afterimage.

"Oh God ..."

Another flash - and another - and then the ceiling lights came on, evenly illuminating the room. Norman saw startled, frightened faces. He sighed, exhaling slowly. "Jesus ..."