Convergent Series (10 page)

One other thing was clear. Whatever had destroyed Perry lived on Quake, close to Summertide.

Which meant that Rebka himself would surely be returning, to a place and to a time where all the evidence proved that humans could not survive.

UAC#: 269
Galactic Coordinates: 26,837.186/17,428.947/363.554
Name:
Umbilical
Star/planet association:
Mandel/ Dobelle (dou-blet)
Bose Access Node: 513 Estimated age:
4.037 ± 0.15 Megayears
 
 

Exploration History:
Discovered by remote sensor observation during the unmanned stellar flyby of Mandel in E. 1446.
First close inspection performed in manned flyby of E. 1513
(Dobelle and Hinchcliffe), first visit by colony ship in E. 1668 (Skyscan class, Wu and Tanaka). First used by Dobelle settlers, E. 1742. Employed routinely as working system since E. 1778.
 

Physical Description:
The Umbilical forms a transportation system that joins the twin planets of the Dobelle system, Opal (originally Ehrenknechter) and Quake (originally Castelnuovo). Twelve thousand kilometers long and forty to sixty meters wide, the Umbilical forms a cylinder which is permanently tethered on Opal (seabed tether) and electromagnetically coupled to Quake.
 

Quake coupling is broken at the closest approach of the Dobelle system's highly eccentric orbit to the stellar primary of Mandell. This closest approach occurs every 1.43 standard years.
 

Variation in Umbilical length is achieved via "the Winch," employing a local space-time singularity (presumed an artifact), which enables the Umbilical to adapt automatically to variations in Opal/ Quake separation. The Winch also performs automatic withdrawal of the Umbilical from the surface of Quake at times of Mandel tidal maximum ("Summertide"). Control technique is understood operationally, but the trigger signal has not been determined (i.e., as time signal, force signal, or some other). Midway Station (9,781 kilometers from Opal center of mass, 12,918 kilometers from Quake center of mass) permits the addition to or removal from the Umbilical of payloads intended for free space launch or capture.
 

Note:
The Umbilical is one of the simplest and most comprehensible of all Builder artifacts, and it is for that reason of less interest to most serious students of Builder technology. And yet it is also something of a mystery in its own right, since although simple it is one of the most recent feats of Builder construction (less than five million years). Some archeo-analysts have conjectured that this fact indicates the beginning of a decline in Builder society, culminating in the collapse of their civilization and their disappearance from the Galactic scene more than three million years ago.
 

Physical Nature:
Defect-free solid hydrogen support cables with stabilized muonium splicing. Cable tensions rival those of human and Cecropian skyhooks but do not exceed them.
 

Transportation car propulsion is by linear synchronous motors with conventional power trains. The technique for cable-and-car attachments is unclear, but related to the Cocoon system free-space nets (see Cocoon, Entry 1).
 

The nature of the Winch is also debated, but it is probably a Builder artifact, rather than a natural feature of the Dobelle system.
Intended Purpose:
Transportation system. Until the arrival of humans, this system had been unused for at least three million years. Currently it is reported in regular operation. There is no indication of other and earlier uses.
 

—From the
Lang Universal Aritfact Catalog
, Fourth Edition.

Quake was changing. Not in the way that Max Perry had warned, moving as Summertide approached from a parched but peaceful world of high seismic activity to a trembling inferno of molten lava flows and fissured ground. Instead, Quake in this year of the Grand Conjunction had become—unpredictable.

And in its own way, Opal might be changing just as much. More than anyone on the planet realized.

That thought had come to Rebka as they were flying back around Opal, from the foot of the Umbilical to the Starside spaceport where Darya Lang would be waiting for them.

Six days earlier the journey around the clouded planet to the Umbilical had been dull, with no turbulence and little to see but uniform gray above and below. Now, with Summertide still twenty-seven days away, the car was buffeted and beaten by swirling and violent winds. Sudden updrafts ripped at the lifting surfaces and jolted the fuselage. Max Perry was forced to take the aircar higher and higher to escape the driving rain, black
thunderheads, and whirling vortices of air and water.

So the inhabitants of Opal were convinced that they would be safe, were they, even with tides far greater than normal?

Hans Rebka
was not so sure.

"You're making a big assumption," he told Perry, as they began a descent through choppier air for their approach to Starside port. "You think Opal's tides this year will be just the same as at other Summertides, but bigger."

"That's overstating things." Once all sight of Quake had been lost under Opal's ubiquitous cloud layer, Perry's other personality had surfaced again: cool, stiff, and indifferent to most events. He did not want to discuss their experiences on the surface of Quake,
nor his mystification at what was happening there. "I do not say that
nothing different will occur on Opal," he went on. "Yet I believe that is not far from the truth. We may get forces too great for some
of the bigger Slings, and one or two of them may break up. But I see no danger to people. If necessary, everyone on Opal can take
to the water and ride out Summertide at sea."

Rebka was silent, holding on to the arms of his seat as
they dropped through an air pocket that left both men floating free
for a second or two. "It may not be like that," he said, as soon as his heart was no longer rising to stick in his throat.

Again and again he had the urge to poke and probe at Max Perry and watch his reactions. It was like control theory, feeding a black box with a defined set of inputs and monitoring the output.
Do that often enough, and the theory said one could learn precisely all of the boxes' functions, though not, perhaps, why it performed them. But in Perry's case, there seemed to be two boxes. One of them was inhabited by a capable, thoughtful, and likable human. The other was a mollusc, retreating into its protective and impervious shell whenever certain stimuli presented themselves.

"This situation reminds me of Pelican's Wake," Rebka went on. "Did you hear what happened there, Commander?"

"If I did, I forgot it." That was not the sort of
reaction that Rebka was seeking, but Max Perry had an excuse. His attention was on the automatic stabilization system as it fought to bring them down to a smooth landing.

"They had a situation not too different from Opal," Rebka
continued. "Except that it involved a plant-to-animal mass ratio not sea tides.

"When the colonists first landed there, everything was fine. But every forty years Pelican's Wake passes through part of a cometary cloud. Little bodies of volatiles, mostly small enough to vaporize in the atmosphere and never make it to the ground. The humidity and temperature take a quick jump, a few percent and a few degrees. The plant-animal ratio swings down, oxygen drops a bit, then in less than
a year it all creeps
back to normal. No big deal.

"Everyone thought so. They went on thinking it, even when their astronomers predicted that on the next passage through the cloud,
Pelican's Wake would pick up thirty percent more material than
usual."

"I think I remnember it now." Perry was showing a distant and
polite interest.
"It's a case we studied before I came to Dobellel.
Something went wrong, and they
came close to losing the whole
colony,
right?"

"Depends who you talk to." Rebka hesitated. How much should he say? "Nothing could be proved, but I happen to think you're correct. They came close. But my point is this: Nothing went wrong that could have been
predicted
with anybody's physical models. The
higher level of
comet material influx changed the Pelican's Wake
biosphere to
a new stable state. Oxygen went from fourteen to three
percent in
three weeks. It stayed there, too, until a terraforming gang
could get in and start to change it back. That sudden switch would have killed almost everybody, because in the time available they wouldn't have had a hope of shuttling everyone out."

Max Perry nodded. "I know. Except that one man down on Pelican's Wake decided to move people offworld anyway, long before
they got near the
comet shower. He'd seen fossil evidence for changes, right? It's a classic case—the man on the spot knew more than anyone light-years away
could
know. He overrode instructions
from his own headquarters, and he was a hero for doing it."

"Not quite. He got
chewed out
for doing it." The car had touched down and was taxiing toward the edge of the port, and Rebka was ready to let the subject drop. It was not the right time to tell Max Perry the identity of the man involved. And although he had been reprimanded in public, he had been congratulated in private for his presumption in countermanding a Sector Coordinator's written instructions. The fact that his immediate supervisors had
deliberately
left him ignorant of those written instructions was never mentioned. It seemed to be part of the Phemus Circle's government philosophy: Troubleshooters work better when they do not know too much. More and more, he was convinced that he had not been given all the facts before he was sent to Dobelle.

"All I'm saying is that you could face a similar situation on Opal," he went on. "When a system is disturbed by a periodic force, increasing the force
may not
simply lead to a bigger disturbance of the same kind. You may hit a bifurcation and change to a totally different final state. Suppose the tides on Opal become big enough to interact chaotically? You'll have turbulence everywhere—whirlpools and waterspouts. Monstrous solitons, maybe, isolated waves a mile
or two high.

"Boats wouldn't live through that, nor would the Slings.
Could you evacuate everyone if you had to, during Summertide? I don't mean to sea—I mean right off-planet?"

"I doubt it." Perry was switching off the engine and shaking his head. "I can be more definite than that. No, we couldn't. Anyway, where would we take them
to
? Gargantua has four satellites nearly as big as Opal, and a couple of them have their own
atmospheres. But they're methane and nitrogen, not oxygen—and they're far too cold. The only other place is Quake." He stared at Rebka. "I assume we've given up on the idea that anyone should go
there
?
"
 

The torrential rain that had plagued their approach to Starside had eased, and the car had come to a halt close to the building that Perry had assigned to Darya Lang as living quarters.

Hans Rebka stood up stiffly from his seat and rubbed at his knees. Darya Lang was supposed to be waiting to meet them, and she must surely have heard the aircar's approach. But there was no sign of her at the building. Instead, a tall skeletal man with a bald and bulging head was standing half-clear of the overhanging eaves, staring at the arriving car. He was holding a garish umbrella above his head. The shimmering white of his suit, with its gold epaulets and light-blue trim, could have come only from the spun fiber cocoon of a Ditron.

From a distance he appeared elegant and commanding, even though his face and scalp had been burned purple-red by hard radiation. Close up, Rebka could see that his lips and eyebrows jerked and twitched uncontrollably.

"Did you know he'd be here?" Rebka jerked a thumb below the window level of the car, so that the newcomer could not see it.

He did not need to mention the stranger's identity. Members of the Alliance councils were seldom seen, but the uniform was familiar to every clade on every world in the spiral arm.

"No. But I'm not surprised." Max Perry held the car door so that Rebka could step down. "We've been gone for six days, and his schedule fitted that time slot."

The man did not move as Perry and Rebka stepped out of the car and hurried to shelter under the broad eaves. He folded his umbrella and stood for half a minute, ignoring the raindrops that spattered his bald head. Finally he turned to meet them.

"Good day. But not good weather. And I gather that it is getting worse." The voice matched the man, big and hollow, with an edge of roughness overlaid on the sophisticated accent of a native of Miranda. He held out his left wrist, where identification was permanently imprinted. "I am Julius Graves. I assume that you received notice of our arrival."

"We did," Perry said.

He sounded ill at ease. The presence of a Council member from any clade was enough to make most people ponder their past sins, or realize the limits of their authority. Rebka wondered if Graves might have a second agenda for his visit to Opal. One thing he did know: Council members were kept desperately busy, and they did not like to waste time on incidentals.

"The information sheets did not provide details as to the reason for your visit," he said, and held out his hand. "I am Captain Rebka,
at your service, and this is Commander Perry. Why are you visiting
the Dobelle system?"

Graves did not move. He stood silent and motionless for another five seconds. At last he inclined his bulging head to the two men, nodded, and sneezed violently. "Perhaps your question is better answered inside. I am chilled. I have been waiting here since sunrise,
expecting the return of the others."

Perry and
Rebka exchanged glances. The others? And a return from where?

"They left eight hours ago," Graves continued, "at the time of my own arrival. Your weather prediction indicates that a—" The deep-set eyes clouded, and there was a moment's silence. "That a Level Five storm is heading for Starside Port. For strangers to Circle environments, such storms must be dangerous. I am worried, and I wish to talk to them."