Several gantry service arms rose out of the departure bay's concrete, carrying pipes and utility cables that were plugged into sockets along the Xianti's belly. Technicians in silver fire suits were walking about underneath, inspecting the huge wheel bogies and keeping an eye on the fueling process. A tall girder tower at one side of the bay had clean white vapor flowing silently out of a nozzle on the top, dissipating fast in the warm breeze. That was the only sign that the spaceplane used cryogenic fuel. Its fuselage remained remarkably free from condensation as the on-board tanks were chilled down and filled.
A pair of Z-B spaceflight division staff stood behind the clearance desk, handing out protective black plastic helmets, similar to the kind cyclists used. They made sure everyone put theirs on before embarking. At the end of the sealed walkway a small grimy window looked back along the huge vehicle. That was the last sight Lawrence was given of the spaceplane—a vast expanse of silver-blue wing surface, its size the only indication of the raw power to be unleashed in the flight. As he walked past he felt that familiar small twist of envy, wishing that he were the pilot who hauled this superb monster up through the atmosphere into space and freedom. Except, as all the years since Amethi had shown him, it wasn't true freedom. At some time, you always had to come back down to earth. That wish was the wonderful deceit that had so far cost him twenty years of his life.
The Xianti's passenger cabin was remarkably similar to that of a standard aircraft. Same worn-down blue-gray carpet, not just on the floor but the walls and ceiling, too; pale gray plastic lockers above the seats, harsh lighting, small vent nozzles hissing out dry air a couple of degrees too cool for real comfort. There was plenty of headroom, though, and the chairs had deep jelfoam padding as well as being spaced well apart. All that was missing were windows.
Lawrence made sure the platoon stowed their bags and strapped themselves in securely before he fastened his own buckles. Seatback screens ran through a few brief safety procedures. Lawrence ignored them. Not that he was blasé about spaceflight, more like pragmatic. At takeoff, the spaceplane carried nearly five hundred metric tons of cryogenic hydrogen. No major emergency was survivable.
The Xianti taxied to the end of the runway, and the human pilot cleared the AS for launch. Four Rolls-Royce RBS8200 turbojets throttled up, producing seventy-five tons of thrust.
They began to race down the runway. Seatback screens showed Lawrence the scenery flashing by; the green blur transferred smoothly into a pale blue as they lifted from the tarmac. Then the huge bogies retracted with a noise more like sections of fuselage tearing off. The blue slowly began to darken.
With full afterburn the turbojets pushed the Xianti up to Mach 2.6 somewhere above the Willis Islands. The scramjet ignited then, liquid hydrogen vaporizing in carefully designed supersonic plume patterns within the hot compressed airflow before combusting in long, lean azure flames. It produced 250 tons of thrust, shaking the cabin with a gullet-rattling roar as it pushed the spaceplane ever higher through the stratosphere.
Lawrence clamped his teeth together as the G-force crept upward and the scramjet's fierce vibration blurred his vision. The pressure on his lungs increased toward the verge of pain. He tried to concentrate on breathing regularly—not easy through the building anxiety. The enormity of their power-dive up into orbit made him understand just how insignificant he was in relation to the energies driving them, how hopelessly dependent they were that the obsolete design programs had been used properly fifty years ago, calculating theoretical parameters of aerothermaldynamic flow; that everything was going to work and keep on working under obscene stresses.
Stars began to appear in the seatback screen as the velvet blue panorama drained away into midnight black. The AS pilot began to throttle back the scramjet as they reached Mach 20. They were at the top of the atmosphere now, still soaring upward from the impetus of the burn. Even at that speed, the oxygen density was falling below sustainable combustion levels. Two small rocket motors in the tail fired up, producing a mere fifteen tons of thrust each, which gently eased the spaceplane up to orbital velocity. They created the illusion that the spaceplane was standing vertical on a low-gravity moon. Lawrence's chair creaked as its struts adjusted to the new loading. At least the pounding roar was over.
The glaring blue-white crescent of Earth slid into the bottom of the seatback screen as the rockets cut off, taking with them the last percentage of G-force. Every nerve in Lawrence's body was screaming at him that they were now falling back to the ground, ninety kilometers below. He took some quick shallow breaths, trying to convince himself that the sensation was perfectly natural. It didn't work particularly well, but he was soon distracted by the sounds of worse suffering from his fellow passengers.
For forty minutes the Xianti glided along its course, passing over Central America and out across the Atlantic. Seat-back screens flashed a quick warning, and the small rockets fired again, circularizing their orbit at four hundred kilometers' altitude. After that Lawrence heard a whole new series of mechanical whines and thuds. The spaceplane was opening small hatches on its upper fuselage, extending silver radiator panels to shed heat generated by the life support systems and power cells. Its radar began tracking the Moray. The orbital transfer ship was twenty kilometers ahead, in a slightly higher orbit. Reaction control thrusters adjusted their trajectory in minute increments, closing the gap.
Lawrence watched the screen as the Moray grew from a silver speck to a fully defined ship. It was three hundred meters long, and about as basic as any space vehicle could get. Habitation cabins were five cylinders clustered together, thirty-five meters long, eight wide. They'd been sprayed with a half-meter layer of carbon-based foam, which was supposed to act as a thermal shield as well as providing protection from cosmic radiation. Lawrence had checked the solarwatch bulletin before they took off. Sunspot activity was moderate with several new disturbances forming, one of them quite large. He hadn't told the rest of the platoon, but he was quietly relieved the transfer would take only thirty hours. He didn't trust the foam to protect him from anything serious. Its original white coloring had darkened to pewter gray as the years of vacuum exposure boiled the surface, and even with the spaceplane camera's poor resolution he could see pocks and scars from micrometeorite impacts.
Behind the cylinders was a life support deck, a clump of tanks, filter mechanisms and heat exchangers. A broad collar of silver heat-radiator panels stretched out from the circumference, each segment angled to keep the flat surface away from direct sunlight.
Next was the freight section, a fat trellis of girders sprouting a multitude of loading pins, clamps and environmental maintenance sockets. For the last three weeks, the Cairns base spaceplanes had been boosting cargo pods up to the Moray and its sister ships. They'd been ferrying them up to Centralis at the Lagrange four orbital point where the star-ships waited, then returning to low Earth orbit for more. Even now there wasn't a single unoccupied clamp. They contained the helicopters, jeeps, equipment, armaments and supplies for the Third Fleet's ground forces; everything they'd need to mount a successful mission.
The final section of the ship was given over to propulsion. It housed two small tokamak fusion reactors and their associated support machinery, a tightly packed three-dimensional maze of tanks, cryostats, superconductor magnets, plasma inductors, pumps, electron injectors and high-voltage cabling. The fifteen heat radiator panels necessary to cope with the system were over a hundred meters long, sticking out from the ship like giant propeller blades. The tokamaks fed their power into a high-thrust ion drive, eight grid nozzles buried in a simple box structure that was fixed to the base of the ship almost as an afterthought.
Moray's length drifted past the camera as the Xianti gently maneuvered itself to the docking tower at the front. Reaction control engines drummed incessantly, turning the spaceplane along its axis as it was nudged ever closer. Then the airlock rings were aligned, snapping together with a clang.
Lawrence took a look aro
und the cabin. Several squaddies had thrown up, and the larger air grilles along the ceiling and floor were splattered with the residue. Checking his own platoon he could see several of them showing signs of queasiness. Hal, of course, had an expression of utter delight on his face. Zero-G didn't seem to have any adverse effect on him at all. Typical, Lawrence thought; he could already feel his own face puffing up as fluids began to pool in his flesh.
The airlock hatch swung open, and the cabin PA hissed on. "Okay, we're docked and secure," the human pilot said. "You can egress the transorbital now."
Lawrence waited until the platoon sitting in front of him had gone through the airlock before releasing his own straps. "Remember to move slowly," he reminded his people. "You've got a lot of inertia to contend with."
They did as they were told, unbuckling the restraints and gingerly easing themselves out of the deep seats. It had been over eighteen months since any of them had been in freefall, and it showed—sluggish movements suddenly becoming wild spins. Desperate grabs. Elbows thudding painfully into lockers and seat corners. Lawrence Velcroed his bag to his chest, and used the inset handles along the ceiling to make his way forward. In his mind, he tried to match the process with climbing a ladder. A good grounding psychology: always try for a solid visual reference. Except here his legs wanted to slide out to the side and twist him around. His abdominal muscles tensed, trying to keep his body straight. Someone knocked into his feet. When he glanced around to glare, Odel Cureton was grimacing in apology, his own body levering around his tenuous handhold, putting a lot of strain on his wrists.
"Sorry, Sarge." It was a fast grunt. Odel was trying not to puke.
Lawrence moved a little faster, remembering to kill his motion just before he reached the airlock. He slithered easily around the corner and through the hatch, pleased with the way the old reflexes were coming back.
The Moray was as crude inside as it was outside, stark aluminum bulkheads threaded with dozens of pipes and conduits, hand loops bristling everywhere. The air reeked of urine and chlorine. It must have been strong: Lawrence's sense of smell was fast diminishing beneath clogged sinuses. One of the crew was waiting for him on the other side of the airlock. Lawrence gave him their platoon number, and in return was told what berth they'd been assigned. Each of the big habitation cylinders was color coded. Lawrence led the cursing, clumsy platoon down into the yellow one. Voices echoed about him, coming from open hatchways—other platoons bitching about the conditions and how ill some of their buddies were and why didn't someone do something about bastard freefall. Twice Lawrence banged himself on the walls as they scrambled their way along the central tubular passageway; elbow and knee. By the time he slipped into their compartment he could feel the bruises rising.
The others crawled in after him, moaning and wincing, looking round sullenly. Their compartment was a simple wedge shape. It had three rows of couch chairs with simple hold-you-down straps, a pair of freefall toilets, a locker full of packaged no-crumble meals, a microwave slot and a water fountain with four long hoses ending in stainless-steel valves. Someone had written: Don't even think about it on the aluminum concertina door of one toilet. What would become the ceiling when the ion drive was running was covered with a sheet screen. It was orientated so that anyone in the chair couches would have a reasonable view. A Z-B strategic security logo glowed faintly in the center purple omega symbol bracketing the earth, crowned by five stars.
Hal stowed his bag and flew across the compartment, turning a fast somersault on the way. "This is fucking amazing. Hey, what kind of i-media are they going to give us, anyone know?"
"You don't get i-media in a crate like this," Odel said in exasperation. "This isn't a pleasure cruise, kid. You worked that out yet? You'll be lucky if they've got black-and-white films." He put his glasses on, leaving the display lenses clear, but settling the audio plugs in his ears. Thin vertical scarlet lines appeared on the lenses as he called up a menu. He worked down a playlist of rock tracks from centuries-old classics right up to Beefbat and Tojo Wall, then settled back contentedly as they began to play.
Lawrence sighed, fastening himself loosely into one of the couch chairs. It could have been worse. Some platoons had boosted out of Cairns ten days ago. At least he only had another four days until the Third Fleet departed from Centralis. Perhaps they could put something in the kid's food.
* * *
Simon Roderick went down to the observation gallery half an hour before the portal opening. There were over a hundred people crammed into the small chamber protruding from the surface of Centralis. Somehow they contrived to give him a little patch of free space in front of the thick glass where he could stand by himself. They were silent, though Simon could sense their minds spiking with resentment and disquiet. As always, he ignored their pusillanimous nature with his usual contempt. The physical discomfort of Centralis itself couldn't be dismissed quite so easily, however.
Centrifugal force didn't make him giddy, although he often caught himself wishing for a full one-gravity field.
Centralis was too small for that, its rotation producing slightly less than two-thirds of a gee around its outermost level.
Back in the mid-1970s when Gerard K. O'Neill was putting his High Frontier concept together he produced several designs for space "islands." Starting with the simple Bernal sphere at four hundred meters in diameter, the concepts progressed up to the paradise garden of "Island Three": linked twin cylinders twenty kilometers long. All of them were admittedly achievable with relatively simple engineering procedures. The problem came in gathering together that much material with the requisite construction crews and their assembly equipment in an era when it cost upward of two hundred million U.S. dollars to launch a single space shuttle.
Scramjet spaceplanes eased the problem of cheaper access to space. But as they helped to build low-orbit stations and their associated industrial modules, so they reduced the need for vast habitats. Even in a rampant consumer society, the quantity of ultraspecialist crystals and chemicals that could be produced only in microgee facilities was limited to a few hundred metric tons a year—a figure easily supervised by small tough crews paid exorbitant salaries to endure the generally unpleasant conditions to be found in Earth-orbit space stations.
It was only in 2070, when a method of faster-than-light travel was developed, that there was any need for large high-orbit dormitory towns. Starships were neither compact nor cheap: they needed thousands of people to construct the massive superstructure and integrate hundreds of thousands of components into a functional whole. As they were too big to take off or land on a planet, they had to be built in space. O'Neill's old ideas were pulled out of university libraries and studied afresh.
One critical development since O'Neill's day was synthetic food production. The old island designs were driven by the need to provide vast amounts of farmland to feed the indigenous population. His cylinders had been given multiple-wheel crystal palace geometries and elegant necklaces of agricultural modules so they would be self-sufficient. The new designs discarded all that baggage. All they needed was a couple of refinery modules to process excrement back into protein cells. The starship companies still kept the idea of a central garden park; that kind of open space was acknowledged as a primary psychological requirement for the crews that would have to spend months if not years up in the islands. And that much biota was a reasonably cost-effective fail-safe air regeneration system. But the rest of it, the luxurious landscapes, meandering freshwater lakes, the giant windows with their fans of mechanically swiveled mirrors, Caribbean climates and nuclear family neighborhoods of open-plan Italian villas—that was all condensed and modernized.
Centralis, which was Z-B's primary Lagrange point facility, adopted a plain cylinder geometry, five hundred meters in diameter and one kilometer long. Its apartment complexes were as cramped as any low-rent city skyscraper, only these were ring-shaped, occupying the lower fifty meters of each circular endwall. The garden between them,
like any urban park, was overutilized and overmaintained. Shrubs and trees grew tall and spindly on the thin layer of crashed rock sand that passed for soil, the fusion-powered plasma tube running along the axis never providing the right level of UV. But it had ponds with fountains and expensive koi carp, and picnic tables, and a jogging track, and baseball diamonds, and tennis courts. Although it took months for the Johnny-come-latelies to pick up on the Coriolis-driven double curve flight of balls.
Radiation shielding, too, was a constant worry beyond Earth's protective atmosphere. The only true defense against gamma rays and high-energy particles was mass, big fat solid barriers of it. Centralis was given a rocky external shield two meters thick, which was encrusted with black radiator fins. There were a few gaps through, for the axial corridors connecting the main cylinder to the nonrotating docking net at each end, shafts for the pipes carrying fluid to and from the fins, and the observation gallery.
Constellations traced a slow curve outside, although the portal was always in view. It hung fifty kilometers off Centralis's rotation axis like a blue pole star. Simon knew where it was only from the cluster of colony trains keeping station around it, slim silver bars agleam with reflected sunlight, forming their own tight little cluster.
He used his DM to receive sensor feeds from the trains, closing his eyes to be greeted with the sight of the portal directly ahead. A simple ring five hundred meters in diameter, it looked like a toroid of black hexagonal netting encasing a weak-glowing neon tube. The sight of one never failed to inspire him, reaffirming his faith in Z-B and all its endeavors. A portal was the most sophisticated, and expensive, technological artifact that the human race was capable of constructing. Only Zantiu-Braun had the facilities, money and determination to build them. Portals were one-shot wormhole gateways. Rather than the continual spatial compression that ordinary starships generated for themselves to fly through, these opened a wormhole down which any vehicle could travel. It took a phenomenal amount of energy, correctly applied against the fabric of space-time, to create the rift. The combined fusion generators of twenty starships wouldn't be able to produce a fraction of the power necessary. So Z-B manufactured an isomer based around hafnium 178 and boosted it up to its K-mixing state; the subsequent decay to its ground state produced the amount of energy required to distort space-time once it was correctly channeled and focused. But the isomer was incorporated into the solidstate wormhole generation mechanism itself, which meant that once the decay was complete the whole edifice was not only useless but highly radioactive as well. You couldn't take it apart and refill it with a fresh isomer. A new one had to be built each time.