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The Swan was rising.
Deneb popped up on schedule, a bright spark above the crater rim. The giant X-ray telescope anchored in the dust of the Korolev Basin revolved in its heavy turret to take an optical bearing on it. The telescope's rudimentary brain made a minor adjustment in alignment, plugged itself into the Farside computer's cesium clock, and waited patiently for the object it had been told to track.
A sizzle of X-rays bounced off the nest of paraboloid reflectors and hit the scanning focus. The telescope became mildly attentive. It was several seconds too early for the appearance of Cygnus X-1.
Then Cygnus X-1 itself rose above the bleak lunar horizon, right where it was supposed to be. Something was very wrong.
The telescope called for help. It took the Farside computer about twelve nanoseconds to check all the possibilities against the star charts stored in its memory. None of them fit. It took another fraction of a second to rule out instrumentation errors. Then the computer followed its standing instructions and alerted the people.
The alarm went off with a ping, and the new duty tech, startled, dropped her stylus and lightpad. Anyone could tell she hadn't been on the Moon long. She bent to catch them much too quickly, and the abrupt motion lifted her bare feet right off the floor. Then she lost track, of her center of mass, toppled over all the way, and went sprawling face downward in slow motion.
The junior astronomy resident grabbed a handful of her smock and set her on her feet again before her eighteen pounds could hit bottom. "Relax," he said with an irritating grin. "You'll get used to it."
He was a six-month veteranof Farside Station himself, a brash, freckled young man who affected faded reg shorts and a shaved chest with his ident disk pasted on it. His name was Kerry, and he fancied himself irresistible. He handed the lightpad back to her with an unnecessary flourish.
Flustered, the duty tech turned to the monitor wall and located the flashing amber light among the banks of glowing buttons and display screens. She began logging the data flickering on the LED panel below it. Suddenly, her eyes widened.
"A new X-ray source in Cygnus," she said. "A strong one."
He leaned over to see. "It must be Cyg X-l."
"No. There's a definite separation. Besides, this one isn't pulsing."
"It's Cyg X-3 then."
"It isn't, I tell you. The computer's already checked for position and emission characteristics."
She wiped the lightpad, thumbing her notes into the computer's temporary memory register, and turned to face him. She was a small, sturdy young woman with a tight, pretty face and a cap of dark hair. Her ident disk said maybury.
"We're famous then." He grinned. "It happened during our shift. How about celebrating with me when we go off duty? I've got a ten-pack in my coop. Genuine bonded joints--gold label, no synthetics."
He leered. Like most of the station's female staffers, she'd elected to go braless in the Moon's less-demanding gravity, and there was an exaggerated tidal motion under her smock.
Before she could squelch him, another ping came from the board.
"The computer wants to divert Polyphemus," she said, frowning.
"Why is it bothering to ask?"
"Dr. Shevchenko's using Polyphemus this month. He's touchy."
"It's your decision."
The duty tech bit her lip and after a moment's hesitation punched in the authorization. The computer thanked her, and pinpricks of colored light began to ripple across the huge circular grid mounted overhead. Dotted lines streamed from the pinpricks, forming a holo image that seemed to converge in infinity. The tech and the resident turned instinctively toward the south observation window. There was a rustle of movement across the floor of the dome as more people turned to stare. Polyphemus in action was an impressive sight.
Out there on the pockmarked landscape a field of enormous metal flowers stretched as far as the eye could see, disappearing over the sharp curve of the lunar horizon, only a couple of miles distant, without diminishing in scale the way Earth-bred eyes said they ought to. Each of those tremendous bowls was as big across as a football field, and there were more than two thousand of them, covering thirty square miles of the Korolev Basin. Now, as the observatory staff fell silent, the whole vast array swiveled in unison until all of them faced the same starry patch of sky.
They were aimed at the constellation of the Swan, still low on the horizon. The duty tech turned her face in the same direction and located Cygnus: a glittering cross with Deneb blazing at its tip. No one could see Cygnus X-1, of course, but Maybury knew it was there, near the place where the arms of the cross intersected. She was very glad it was ten thousand light-years away.
She shuddered, trying to imagine it. The thing called Cyg X-1 was an X-ray inferno, shedding an invisible glare equal to the total energy output of ten thousand suns. If it had any planets, it had fried them long ago.
Vampire stars--that was what X-ray sources like Cyg X-l generally turned out to be: black holes or neutron stars that circled a blue supergiant companion, relentlessly sucking away its gases. As the gas fell into that terrible gravitational field, it was squeezed, bruised, heated to temperatures of up to 100 million degrees Kelvin. In the process it gave off that raging hellfire of X-rays.
The odds were that the new source in Cygnus would turn out to be something similar. The evolution of such X-ray binaries had been well understood since the late twentieth century: A massive star swelled as it burned up its hydrogen fuel, overflowing its Roche lobe and contributing mass to its companion. A supernova explosion in the burnt-out star left a black hole behind. And then, for a brief period of thirty or forty thousand years, a reversal of the mass exchange as the companion star in turn burned up its hydrogen and bloated to a blue supergiant, while the relentless hole devoured its substance. The Farside computer would be comparing its X-ray and radio images now, trying to fit its accumulating data into such a picture.
Another ping brought her attention back to the board. The junior resident peered over her shoulder.
"The computer's found something it can't handle," he murmured. "It's just plugged itself in to the data center at Mare Imbrium."
The two computers, on opposite sides of the Moon, began exchanging data. After a couple of seconds the console buzzed to catch the humans' attention, and a new request flowed across the screen.
"Now it wants the use of the five-hundred-inch reflector," the resident said.
The tech bit her lip again. "I'd better get Dr. Ruiz," she said.
"He won't like it. He was up all night."
But the duty tech already had spoken into her lapel communicator and asked the desk to wake up Farside's director.
By the time Dr. Ruiz arrived, green-smocked technicians and off-duty personnel were milling around the area. Word had spread quickly that something was going on, and curious faces peered into the glass-walled monitor booth.
Ruiz pushed through the crowd and closed the door of the booth behind him. He was a tall, gaunt man, slightly stooped, with hollow cheeks and a leathery complexion. His knobby legs showed the effects of childhood malnourishment. His eyes were bleary with lack of sleep, and he was still tucking his singlet into his baggy shorts.
"I'm sorry, Dr. Ruiz, but--"
He waved her apology aside. "What's this about the computer asking to divert the Sagan reflector?"
"It's true, Doctor. It's already diverted the Polyphemus array. Now it apparently wants to try for a counterpart image at the visible wavelengths. But with optical-viewing time booked three months in advance, I thought I'd better--"
"Yes, yes. You did the right thing to call me." The director's eyes already were roving restlessly over the winking lights and flickering data screens of the big board. "What have you got so far?"
The tech turned on her lightpad. Her handwriting and underlinings, in scratches of blue lightning on the pad's polycrystalline surface, crowded the computer-generated script she had dialed in from the board.
"Well, for one thing it doesn't pulse. It just gives off a steady X-ray emission consistent with a point source."
"Hmmm. How about the possibility of sinusoidal variation with a period of several hours, like Cyg X-3?"
She shook her head firmly. "The computer's been tracking it long enough to have detected a curve. It's a radio source, too. We have a fix on it with Polyphemus."
Ruiz raised a shaggy eyebrow. "You diverted Polyphemus?
She stood her ground. "Yes, Doctor. I'm authorized to--"
"Don't worry about it." He laughed. "I'll deal with Dr. Shevchenko. You're doing fine so far. Go on."
The junior resident butted in, trying to get himself noticed. "Excuse me, Dr. Ruiz, but the X-ray source is only a couple of seconds of arc from Cyg X-1. It confused the telescope at first. Doesn't that suggest that it's been occulted by X-1 until now?"
"And what do you say"--Ruiz squinted at the duty tech's ident disk--"Mizz Maybury?"
The tech blushed. "It's only twenty-eight days since the last sighting. Cyg X-1 is over ten thousand light-years away. The new source couldn't have been hiding behind it. For the apparent separation to increase that much, it would have to be moving laterally at several hundred times the speed of light."
"And what does that suggest?"
Maybury gave the junior resident an apologetic glance. "That it's the other way around. The new source may have been masked by Cyg X-l, but it's closer to the solar system."
"My thought exactly."
Ruiz walked over to the observation window, an imposing and dignified figure despite his baggy shorts, his knobby joints, the legs twisted by rickets that were his legacy from his childhood in New Manhattan. He looked out at the starry sky and located the Swan. He stared at it a long time, as if he were making up his mind about something.
With a casualness that made the other two gasp, Ruiz turned back to the board and punched in an authorization for the immediate use of the 500-inch Sagan mirror in the Tsiolkovsky crater. Diverting the giant telescope from high-priority projects wasn't something you did lightly, even if you were the director of Farside Station.
Instantly, a stunning image sprang into life on the photoplastic viewplate. It was truer and richer than the images that had been possible on the obsolete photographic emulsions of the twentieth century. There was no graininess with enlargement. They were seeing, in real time, exactly what the big eye was seeing halfway across the Moon.
There was an illusion of stars swimming across the plate, as electrical potentials changed on the plastic's surface. The stars halted as the Farside computer locked the telescope into the Polyphemus radio array.
The blue supergiant known as HDE 226868 was plainly visible as a bloated disk, thanks to computer enhancement of thousands of separate millisecond-long exposures. You could even see the pronounced bulge at one side, where its substance was being sucked away by its invisible companion--invisible because black holes swallow their own light, as they swallow everything else.
Ruiz made the computer generate a phantom image derived from radio waves and X-ray scatter. A fuzzy speck of cotton appeared opposite the tip of the bulge. He shifted focus and found another cotton ball halfway between Cyg X-1 and Deneb. Whatever the new source was, it wasn't part of a binary. He frowned.
Maybury had been busy comparing her first entries on the lightpad with the updated figures on the board. "Dr. Ruiz," she said in a puzzled tone, "there's no proper motion that the computer can detect. I know the observational sample is still very small, but the new object seems to have stopped its lateral movement. She hesitated. "That would mean that it's changed direction twice in the last twenty-eight days."
The junior astronomy resident snorted. "That's impossible!"
Nobody paid any attention. Ruiz looked thoughtful. "Mizz Maybury..."
She was way ahead of him. She scribbled a question on her lightpad and read off the answer that appeared a moment later.
"The computer says that both the radio waves and X-ray emissions are blue-shifted," she said. "It's been compensating for our benefit."
"That means that the object is moving toward us," the resident said brightly.
Ruiz switched off the ghost image and stared intently at the place where it had been. There was nothing visible.
But Deneb jiggled.
The others saw it too. All of a sudden the room was very quiet.
"Mizz, Maybury," Ruiz said, "will you ask the computer to generate a star chart on this screen? Just the main reference points will do."
"I'll do it," the junior resident offered.
A scattering of white crosses appeared on the screen, canceling out the stars. But Deneb was still there, displaced inward toward the cotton ball.
"It's bending light, whatever it is," Ruiz said. "And it's between us and--"
Angry squawking from the wall communicator interrupted him. He looked up and saw the apoplectic face of Dr. Mackie, the chief astronomer at the Sagan dome.
"Dr. Ruiz!" Mackie sputtered. "I must protest the highhanded manner in which you preempted the schedule of the five-hundred-inch mirror. There are such things as review boards, and I can assure you that--"
"Calm down, Horace," Ruiz said. "I think you'd better get over here right away."
Mackie's truculence faded suddenly. "What have you got?" he said carefully.
"I'm not sure, but I want you in on it. Requisition the courier rocket. If you leave right away, you can be here in an hour."
As soon as Mackie switched off, Ruiz called Central Communications. "Put this through to the Mars station. Personal, direct to Dr. Larrabee at the Syrtis Major radio observatory. Wake him up if he's asleep."
"You're on, Doctor," Communications said.
Ruiz spoke rapidly and precisely into the communicator, giving coordinates, explaining the situation in as few words as possible. "...And, Larry," he finished, "don't waste time calling me back for a confirmation. Just do it."
He switched off and settled back in one of the swivel chairs. "How about some coffee while we're waiting?" he said.
The wait was over an hour. There could be no such thing as a conversation with Mars, particularly when Mars was on the other side of the Sun, as it was now. As the crow flies, it would take radio waves a bit more than twenty minutes to travel one way. But the crow would not fly through the sun. The message had to be bounced off the relay satellite orbiting Venus, currently a quarter orbit ahead of Earth, and in line of sight with both Earth and Mars. The round trip for an exchange of messages, with the detour, would take about an hour, even if Larrabee answered immediately.
He answered almost immediately. Ruiz was into his third cup of lukewarm coffee when Larrabee's voice came out of the wall, clear as a bell, with all the interplanetary static edited out by the computer. Voice transmissions from Mars were sent in pulse-code modulation with triple redundancy, and in the unlikely event that any particular pulse was wiped out all three times, the gap was too infinitesimal for the human ear to detect.
"I don't know what this is all about, Hernando," a cheerful baritone said, "but I'll take your word for it that it's important. We're zeroing in on your Cygnus source now. Just sit tight a couple more minutes. I'll keep the beam open. You owe me a drink when I get back."
Ruiz sipped another cup while the resident, Kerry, hovered around him and Maybury punched setups into the board. The new shift had arrived, and they were tiptoeing around, trying not to look curious. Ten minutes later, lights started blinking all over the board as the Mars computer fed data via radio into the Farside computer's memory buffer register. The computer, consulting its hydrogen maser clock, corrected for transmission delay.
Before astronomers had set up shop on Mars, they had had to wait six months to measure parallax. You took a picture of your target star, and when the Earth had traveled halfway around the sun you took another picture on the same plate and measured the apparent shift. Now you could triangulate by taking sightings from the Moon and Mars simultaneously.
Ruiz watched the figures unreeling on the LED displays, his coffee forgotten. In his mind he translated them into a triangle with a base line that was 234 million miles wide. If the X-ray source was anywhere within a hundred light-years, he'd get reliable results.
Two glowing dots appeared on the viewplate against a background of stars; the computer had enough data now to attempt a preliminary visualization. Who had asked it to do that? He looked up--that technician, Maybury. She was efficient. That fool with the shaved chest was doing nothing except stand around looking important.
Ruiz looked back at the screen and blinked. The dots had stopped jiggling. They were impossibly far apart. The parallactic shift was ... huge!
The damned thing was less than a light-year away!
He snatched the lightpad from a startled Mizz Maybury and made his own rough calculation. His answer approximated the computer's average figure: a distance of about half a light-year. The Cygnus source was close--closer than any stellar object had a right to be. And it wa blue-shifting. And there was no proper motion. All the motion was head-on.
Something soft nudged his arm: Mizz Maybury's breast. She was leaning across him, thrusting a piece of paper in front of him, trying to get his attention.
"Dr. Ruiz!" she said urgently. "I thought you might want--that is--I asked the computer to pull out the most recent planetary data. The positions of the outer planets--I mean, there's a discrepancy of several seconds in the longitude and declination of both Neptune and Pluto. It might turn out to be simple observational error, but--"
He waved her aside. "In a moment, Mizz Maybury." He was staring intently at the screen that showed the values for the base angles. The computer was constantly updating them as it refined and reaveraged its data. They held steady up to the eighth decimal point, then jumped back and forth a good deal, but the trend of the figures was definitely higher.
The thing had to be moving fast to show any noticeable change in that short a time. Ruiz was almost afraid to ask how fast. But he wiped the lightpad and scribbled an order for the computer to pin a tentative value on the blue shift and try to correlate it with the changing parallax. There was a pause of several seconds while the computer searched its peripheral memories for an appropriate program; then figures began to flow across the lightpad, while a duplicate column of numbers marched across one of the display screens.
He heard a gasp behind him. Maybury was looking over his shoulder.
"That's right," he said. "It appears to be moving toward us at something more than ninety-eight percent of the speed of light."
Over at the data screen the junior resident cleared his throat. He was perspiring, and the green ident disk on his chest was coming unstuck. "That means it'll be in the vicinity of the solar system in about six months," he said.
"At its present speed, yes," Ruiz said.
He drummed his fingers on the arm of the chair. Finally he said, "I don't suppose we'll really have enough data till we've observed it for a few more days, but why don't you have the computer generate a projection of the path of the Cygnus source through the solar system."
Maybury and the young man got busy over at one of the consoles. Ruiz could hear them whispering together, having some kind of dispute, but he wasn't paying attention. He was thinking about the trip to Earth he'd probably be making some time in the next twelve hours, dreading it. He glanced up and saw the junior resident, an angry flush on his face and chest, step away from the console and stare sulkily out the observation window. Maybury was hunched over, shoulders tense, her fingers flying over the lightboard, her bare toes twiddling in unconscious rhythm. At last she straightened up and turned in her chair.
A flat disk grew in the square darkness of the holo well. It looked something like a target, with the sun and the orbits of the inner planet crowded together to make a bull's-eye. In the computer's stylized representation, Pluto's orbit was a tilted hoop intersecting the orbit of Neptune, which had briefly replaced it as the outermost planet beginning in 1987.
A yellow dotted line with an arrowhead represented the probable course of the Cygnus source. It wiggled back and forth a bit as the computer changed its mind, but it always intersected the plane of the ecliptic somewhere near the edge of the bull's-eye.
Ruiz canted the image for better perspective and zoomed in so that Jupiter's orbit was outermost. Now he could see the positions of the inner planets--colored beads strung on those glowing tracks, and necessarily out of scale. Six months hence, Mars would just have overtaken Jupiter, and Earth would be rounding the Sun to catch up.
That X-ray holocaust from Cygnus was going to penetrate the plane of the solar system somewhere between the orbits of Jupiter and Mars. It would pass within 4 A.U.s of Earth.
Ruiz rose out of his chair very carefully, like an old man, and walked over to the observation window. He took another long look at Cygnus, knowing it was futile. If the 500-inch telescope couldn't see anything, he certainly wasn't going to see anything with the naked eye. The duty tech made no attempt to follow him with her piece of paper. Even the junior resident had sense enough not to say anything.
Dr. Mackie arrived a few minutes later, still wearing his pressure suit, his helmet tucked under his arm and his turkey neck sticking out of the collar ring. He saw the look on Ruiz's face. "What's wrong?" he said.
Ruiz was a tough old bird. He had grown up in the squalor of a refugee camp on Long Island in the years after most of Manhattan had been rendered uninhabitable by the bomb, made of stolen reactor wastes, set off by the New England Separatists in 1998. He had clawed his way to the top on his own merits, despite the twin handicaps of poverty and a provisional ident. There wasn't much that could unnerve him.
But now his face was gray as he turned to Mackie.
"I'm putting you in charge, Horace," he said. "I'm going down to Earth to tell them that the human race has just been sentenced to death."
Posted October 25, 2008
No text was provided for this review.