Donald Moffitt - The Jupiter Theft

For Ann, whose energy is greater than her mass

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 veteran of 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?”