He sat in the padded control chair, nervously fingering with his right hand the panel of switches before him. He was calling up displays on each of the screens in turn, a reflex action carried on by his fingers independently of his brain.
One more day. Then he could permit the first operation.
He decided that he would run over everything just one more time. After that, he would go to bed. Luis had called earlier, and Rob had emphasized the need for a good night’s sleep before they began the final tether. They would need their brains clear and rested when the time came. Luis was probably back in Quito sleeping like a baby; Rob doubted he would be able to sleep at all.
He flicked in a display of the silent control room in Quito, then went one by one around the geosynch reporting stations. He inspected the caboose last of all, the unmanned mass of equipment that hung at the very end of the beanstalk. Everything was quiet, physical variables well within their tolerances. Even the Sun was behaving itself, with no new flares and prominences to change the density profile of the upper atmosphere.
Rob’s obsessive checks and counter-checks did not go unobserved. Corrie drifted quietly in during the long countdown. She stood behind him without speaking, watching the parade of images as they moved across the big screen. She too had tried, in vain, to persuade Rob to postpone the landing until his condition improved.
Finally Corrie turned and left. She could share only so far in the excitement and the tension that consumed Rob.
One more day, and then the operations could begin to replace his hand. He had given his promise. But would he keep it — or would some new goal emerge to fill his life?
One hour. Contact minus 4,000.
The first abort option had passed. The beanstalk was moving faster now, arcing in towards Earth along the smooth curve of an Archimedean spiral. From a head moving along at ten kilometers a second, the thin filament curved around through more than three hundred degrees to its bulbous tail. Three billion tons of inertia began to make their presence felt. As the beanstalk swung in toward Earth impact, the elements of the cable could not follow their natural free-fall pattern. Instead, tensions were building along the whole length, constraining the diving head to follow an approach path that would turn gradually to the planned landing point at Quito.
Stored elastic energy was growing within the load cable. Already it matched that of a medium-sized fission bomb. If the cable snapped, the energy would release as a shock wave along the length of it.
Rob looked at the readings from the strain gauges set all along the axis of the beanstalk. They still shared low values, negligible compared with their final planned maxima. He switched to the screen that monitored the orbit of the ballast asteroid. Soon it would reach perigee. In thirty minutes it would begin to swing out again, away from Earth. For the moment nothing needed to be done. Rob checked the Doppler broadening from the asteroid observations, confirming that they showed an acceptably low rotation rate for the ballast.
There was still plenty of time for an abort option. The beanstalk had not yet started its final straightening. High-reaction drives attached to the head could swing it away from Earth and curve it clear. When the drives were jettisoned in another forty minutes, at least some part of the stalk must enter Earth’s atmosphere.
It was not only the tensions in the beanstalk cable that were growing as the fly-in continued. Rob could feel a mounting discomfort, like a rock sitting in the pit of his stomach. Nothing on the bridge construction projects had prepared him for this, for the convoluted juggling of multiple forces implied by the landing of the stalk. Although the control panel gave him nominal control of operations, Rob knew that he was actually helpless. Everything depended on the accuracy of the calculations and the realism of the simulations they had done. Nothing that he — that any human — did now could improve the pattern of approach. He was at the center of the Control System, with only one decision left to make: abort, or continue the landing? The simple flip of a binary switch, that was what it all came down to. Rob was feeling less and less able to comprehend all the factors that would guide the decision. After the physical and mental turmoil of the past two weeks his brain felt numbed and slow, incapable of accurate evaluation. He bit his lip until it hurt, focused all his attention on the displays, and waited for the next datum point on his decision tree.
He had never expected to be so isolated. In all his plans, all his thoughts about the landing and tether, Regulo would be in close radio contact, assessing, advising, reassuring. No matter what the record books might show, this project was not Rob Merlin’s; it belonged to Darius Regulo, its originator, its designer, its only begetter.
Rob felt alone in his worries. He was not. In hundreds of outrider ships along the length of the stalk, in other vessels that matched the course of the great ballast weight, and in the hot and cramped offices of Tether Control, men and women sweated over the same display images, frowned at the same incoming data streams, and thanked Fortune that the final abort decision was not theirs to make.
All around the world, people were beginning to watch the sky. It was too soon to see anything; but logic did not control their actions.
Contact minus 600.
With ten minutes to contact, the diving head of the beanstalk reached the upper atmosphere. It entered the ionosphere and began to feel the first effects of frictional heating. Now it was starting to slow in its descent. The long tail, way out beyond synchronous altitude, was already tugging upward to provide a colossal outward tension that would slow all downward motion. The cup that hung at the very end of the beanstalk was moving higher and higher, sling-shotting out from the first approach spiral to stretch away from Earth. Eighty-five thousand kilometers above the surface, it formed the final point of a stalk that reared steadily closer to the vertical.
Looking down from the outer cup, an observer would see the shape of the beanstalk gradually straightening beneath, moving to make a clean line that dropped endlessly away to the distant Earth. The same observer, looking far out ahead of the swinging cable, would see the ballast asteroid, still thousands of kilometers away but rapidly coming closer.
The tension in the load-bearing cable had increased by two orders of magnitude in as many hours. It was still less than the final figure for the installed beanstalk, but already the stored energy exceeded that of any fusion weapon. Longitudinal waves of compression and tension rippled constantly along the length of the load cable, transmitting balancing forces from the out-flying higher end to the downward plummet of the lower cable.
Observers in Quito had heard the crack as the head passed through supersonic speed. Now they waited for the first sight of it. Along the equator, far to the west of Tether Control, a thin line of contrail at last became visible. It spread from the speeding head of the stalk in a wake of turbulent ice crystals. The shadow formed a dark swath on the equator, neatly bisecting the globe into north and south hemispheres. There was a steady rumble like approaching thunder.
High in the Andes, Indian peasants paused in their daily work of scratching the stubborn soil, long enough to offer their prayers to the old gods of the storm. Luis Merindo watched the scopes in Tether Control and sought the same reassurances from the newer deities of aerodynamics and electronics. The head of the beanstalk was a millisecond off at the first triangulation point. How much would that become when it reached the pit? He was relieved to see an estimate from Santiago flashing up onto his display. Just a few meters. They had more than enough margin for that at the pit.
As soon as atmospheric entry was initiated, Rob’s attention moved to the temperature sensors set throughout the length of the stalk. The change in gravitational potential as the beanstalk dropped would appear partly as kinetic energy and partly as dissipated energy within the stressed interior of the cable. That stretching and flexing would appear as adiabatic heating and cooling, driving the local temperature up and down differentially along the length. A thousand degrees was the limit. With ample strength at norma
l temperatures, the cable would weaken drastically above a thousand. The calculation had been one of the trickiest parts of stalk design, a bewildering maze of orbital dynamics, nonlinear elasticity and thermal diffusion.
Rob was relieved to see that his estimates were on the conservative side.
Contact minus 60.
The cupped upper end of the beanstalk, moving almost tangentially to the curve of the Earth’s surface, engulfed the ballast asteroid. The mesh of silicon threads that formed the cup began to take the strain as the ballast sought to continue its upward path. After one second, the stresses stabilized. The trajectory of the upper end of the beanstalk now became geostationary, moving to remain vertically above Quito ’s tether point. The tension in the cable was close to the design maximum value of eighty million newtons per square centimeter. Although the head still descended, that movement was less and less rapid.
The blunt lower end of the beanstalk was visible now from Tether Control. Its movement seemed almost leisurely. It descended like a sluggish, questing blind-worm seeking the pit that would house the tether. Luis Merindo watched his displays as the head disappeared behind the towering piles of rock around the hole. He checked his read-outs. In-filling would begin in thirty seconds. After that, only one question meant anything: Would the tether hold, against the billions of tons of upward force created when the ballast swung wide and high above synchronous orbit?
In the secondary viewing room at Santiago, Howard Anson was also watching the head of the beanstalk. He had no feeling for engineering, and the sight for him brought memories from another time of apocalypse. “Then will I headlong run into the Earth,” he whispered to himself. “Earth gape. Oh no, it will not harbor me. Mountains and hills, come, come and fall on me, and hide me from the heavy wrath of God.”
That earned him a peculiar look from the senate aide sitting next to him. Anson wondered if the man was objecting to his liberties with Marlowe’s classic text. He smiled and shrugged in an embarrassed way, and the other turned his attention back to the screens.
All opportunities for abort were now past. The remaining question centered on the tether. Unless that held, the beanstalk would be dragged from its temporary lodging north of Quito and swing up and away again, out past the Moon. The huge inertia of the system meant that even this question would take many seconds to answer by eye; the smart sensors on the beanstalk would know it in less than a heartbeat.
Contact.
The base of the beanstalk touched the bottom of the pit, five kilometers below ground level. As it did so, mountains began to move. Landslides were following the broad head of the beanstalk into the depths of the prepared chasm. The rumble of detonations, placed carefully around the edge of the pit, merged into the continuous roar of a billion tons of rock as it fell into the pit and packed down under the pressure as more earth and boulders followed.
It was the time of maximum stresses. The cable, caught tight at head and tail, flexed and contorted along its length like an agonized snake. Local transient stresses were running above a hundred million newtons per square centimeter. Each gauge monitored by the control panels changed and changed again, too fast for any human to follow. The central computer analyzed the incoming data stream, decided on the most critical variables, and passed along a status report simple enough and slow enough to be understood by humans.
There was room in Rob’s head for only three questions: Were the oscillations along the length of the cable in an unstable growth mode? Would the ground tether hold? Was the ballast asteroid secure in its holding cup, a hundred and five thousand kilometers above the Earth?
Five seconds passed. The flickering chaos of signals on the board in front of him began to smooth to a pattern that he could follow even without computer assistance.
Stresses and temperatures were reporting within tolerances.
The ballast was firmly attached at the beanstalk’s upper end.
Signals from Tether Control implied a secure anchor. The final few hundred million tons of rock were falling to the bottom of the pit.
An army of robots stood ready to deploy along the beanstalk.
It was ending, in a mutter of damping stresses and a groan of settling rocks. The beanstalk, stretched tight between the opposing forces of ballast and tether, was molding to a stable configuration, a vast arching bridge between Earth and Heaven. The path was secure between Midgard and Asgard.
Three minutes after Contact, Rob felt comfortable enough to switch displays to the powersat. It was in the right position, lagging the stalk enough to be well out of the way had trouble arisen, close enough to be moved easily to contact with it when the time was right. He signalled it to move in and begin to attach to the superconductors. With ample power for the drive ladder, the robots could begin installation of cargo and passenger transport modules.
As the powersat made its first connection with the beanstalk, Rob switched to yet another camera. This one was set in the powersat itself, near the point where the superconductors would be hooked on.
Rob’s intention was to check the position of the leads, but the camera was coincidentally looking straight down along the length of the beanstalk. In the observation center where Howard Anson and Senta Plessey were located, a communal groan went up from the onlookers. The senate aide next to Anson grunted, as though he had been hit hard under the ribs.
“Jesus H.” He turned to Howard and Senta and shook his head. “Do they think they’ll get people to ride that thing? It turns my stomach to think of it.”
His eye, like everyone else’s, was following the cable endlessly down toward Earth. Views from rockets were common enough, but they never gave the onlooker a true feeling for height. There was no direct connection, nothing to tie the mind back unavoidably to the real globe beneath. The beanstalk changed that. There was no doubt here that they were looking down — a long way down — even though the cable itself shrank to invisibility against the background of the cloud-covered planet. As they watched, the first of the maintenance robots moved out from the powersat and began to crab its way precariously down the drive ladder. It was checking the current in each segment, readying for the deployment of the ore carriers, and its hold on the beanstalk was in fact completely secure. The onlookers didn’t know that — or care. The observation center was gripped by a total and breathless silence.
“Are they really planning for passengers?” whispered the aide, almost to himself. “I can see them using it for cargo, but not for people.”
Senta turned to him and patted his arm. “Don’t worry.” She smiled. “I feel the same way that you do, but they won’t ask anybody to use it who doesn’t feel comfortable. All the passenger cars will be closed in, so you won’t get any feeling of height. Think of it as just a great big elevator.”
“Elevator?” The aide gave her a sickly smile and turned back to the display. “Funniest damn elevator I’ve ever heard of. It would take you hours and hours to get up or down.”
“More than that,” Howard Anson said softly. The sight of the cable confirmed all his fears of space travel. “It would be a five-day trip, one-way. And once you started out there’d be no changing your mind. You’d have to ride it all the way.”
“Well, you can have my share of it.” The aide was still staring in horror at the big screen. “I’ll stick to good old rockets. I don’t mind being thought old-fashioned. Look, suppose the power failed on that thing? You’d fall off it and you wouldn’t stop falling until you hit Quito.”
“You can’t fall off,” said Senta. She seemed to be the calmest person in the room. “If the power failed, the cars will stick to the drive train with a mechanical coupling. You’d just hang there until they started the power up again. Anyway, if something did fall off it wouldn’t land at Quito. If you fell off from high enough, you’d miss Earth completely, and finish up back near the point you started from.”
“Charming.” Their companion grunted his displeasure. “And how long would all that take? I was once s
tuck on a funicular railway for seven hours, and believe me, it felt like seven hours going on seven years. Suppose the power doesn’t come back on? What are you supposed to do, shin down the cable on your own?”
While the aide was speaking, Howard Anson had turned to watch Rob’s reaction to the view on the big screen. What he saw disturbed him. This should be the moment of triumph, the point where the architect of the beanstalk was relaxing and smiling and giving the thumbs-up sign to everyone in sight.
Rob was slumped in his seat, the stump of his left hand held across his chest and cradled in his right. As Anson watched, Rob yawned hugely, slowly stood up, and stumbled like a drugged or drunken man toward the door of the Control Center.
“Come on, Senta.” Howard Anson came quickly to his feet. “The show’s over. Rob needs help.”
“He’s all right.” The senate aide examined Rob’s image. “I’ve seen that expression before. When you finish a big, complex job, you get a feeling like nothing else in the System. It’s the biggest high in the world, and at the same time you feel so weak and tired that you can’t really think at all. Merlin is coming down, that’s all.”
“I wish you were right.” Anson was at the door. “But I don’t think so.”
When they reached Rob he was standing motionless by the communicator at the entrance of Central Control. He was staring at it expectantly. Anson gave the operator a questioning glance.
The woman nodded. “I don’t have this on the schedule, but we have an incoming signal forwarded through lunar relay. Here comes the video.”
The communicator screen lit up. Darius Regulo’s battered countenance appeared.
While Senta Plessey gasped and Rob went rigid, Regulo spoke. “I’m sure it’s looking good. Better than good, Rob — perfect, everything on the button. Congratulations. I’ve watched you do it, but the beanstalk is all yours. Twenty years from now, people are going to marvel at the way that Earth managed to struggle along without it. Go out and enjoy yourself, savor the moment. You won’t get a feeling like this many times in your life. I wish I could be there to help you celebrate, instead of being stuck here on Atlantis.”
The Web Between the Worlds Page 26
