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 blasй 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.