Titan

by Stephen Baxter

  The rocket engine was putting out full thrust. Now, for the next eighty or ninety seconds, it was Deeke’s job to ride this bull, to keep X-15 on the track that had been programmed for it on the ground.

  Soon he would be accelerating at multiple Gs, which meant adding ninety miles per hour every second.

  He’d forgotten how impressive an aircraft X-15 was.

  “Should be coming up on alpha,” the ground said.

  Seven seconds. Deeke turned three degrees to the right to correct his heading. He kept one eye on the cockpit clock. Nine seconds. Ten seconds. Timing was everything in an X-15 flight. He checked his angle of attack, angle of sideslip, roll attitude, rate of climb.

  Fifteen seconds. The acceleration looked nominal, still under two G. He watched his pitch attitude vernier needle, which was starting to come off its peg. Here it came, at eighteen seconds, moving towards the null position. At twenty seconds the needle was centered and he eased off on his angle of attack, to maintain the planned twenty-five-degree climb angle.

  “You should be on pitch attitude now,” the ground said.

  “Rog. Track looks real good. I feel as it I’m back in the saddle again. I wish I could do a barrel roll.”

  “Rog that,” the ground said anonymously.

  Yeah. You aren’t here to enjoy this, Linebacker.

  At fifty thousand feet he shot through a layer of gray, hazy cloud. He emerged into a blue, infinite sky. The sun was still low, and it cast shadows on the ocean of cloud beneath him, which obscured the Earth.

  He looked ahead, half expecting to see the Shuttle’s vapor stack, ahead of him; but his tipped-up windows showed him nothing but sky.

  The handover from the KSC Firing Room had been as smooth as Barbara Fahy could have asked for. She didn’t even have to say anything. The ascent, complex and dangerous as it was, was just a process, she reflected, something they had handled more than a hundred times before, unfolding now with the inevitability of the logic of a well-tested software program.

  Only the brilliant rocket light on the projected display at the front of the room gave any hint of the violence of the events the FCR’s devices were monitoring.

  Even so, Fahy found it difficult to breathe.

  … Now a new voice sounded in her ear. It was the range safety officer. It seemed that some unknown aircraft had wandered into the exclusion zone around the ascent profile.

  Benacerraf looked ahead, out of the window beyond Angel. A layer of cloud hurtled at the orbiter like a wall. Endeavour shot through in a second, and emerged under a deep blue, domelike sky.

  Angel closed switches, configuring the attitude indicator before him.

  “There’s Mach point nine,” Libet said. “Okay, Mach one. Going through nineteen thousand.”

  Forty seconds, Benacerraf thought, to reach the speed of sound from a standing start.

  “Forty-four seconds.”

  “Houston, Endeavour. Max Q. Into the throttle bucket.”

  Max Q was a moment of danger, Benacerraf knew, the moment at which the Shuttle stack’s gathering velocity, coupled with the still-high density of the air, exerted maximum aerodynamic pressure on the airframe. The main engines had briefly throttled down to relieve the pressure.

  “Copy,” Marcus White called. “Fifty-seven seconds. Endeavour, Houston. You are go for throttle up.”

  “Copy that. Throttle up.”

  “Wow,” Libet said, “feel this mother go.”

  “Sixty-two seconds,” White said.

  “Thirty-five thousand,” Angel said. “Going through Mach one point five.”

  “Here we go,” Libet said. “SRB pressure is dropping.”

  Already the solid rocket boosters were burning out.

  “One minute fifty,” White called up. “Twenty-one miles high, eighteen miles down range.”

  “Houston, Endeavour. Pressures less than fifty psi.”

  “Copy.”

  “SRB burnout.”

  As the solid boosters died, it felt to Benacerraf like a dip, as if the Shuttle was suddenly falling out of the sky, just for a second. But then the acceleration built up powerfully once more.

  “Ready for SRB sep.”

  “Roger.”

  There was a bang and a bright flash, beyond the orbiter’s panoramic windows, as the boosters’ separation motors ignited. It was as if she flew through a fireball.

  “Okay, Linebacker, we have you right on track, on the profile.”

  “Rog.”

  Thirty-one seconds. The rocket burn roared on. Deeke worked his way around checks of his engine instruments, hydraulic pressures, generators, APU temperatures, stabilizer positions, cross-checking his altitude and velocity and rate of climb.

  Thirty-five seconds. He shifted in his seat slightly, trying to get more comfortable; the G was already above two and was climbing fast.

  “Stand by for eighty-three thousand feet.”

  “Rog, eighty-three thousand.” Now his altitude too was piling up rapidly.

  “Do you still read us, Linebacker?”

  “Affirm.”

  “Coming up on a hundred and ten thousand.”

  “Hundred and ten, affirm.”

  “On the profile, on the heading. On the profile.”

  A minute fifteen.

  He was already above the bulk of the sensible atmosphere. Ahead and all around him, the sky started to turn from a pearl blue to a deeper, dark blue. His vision seemed to stretch to infinity, to the gently curving, blue-white horizon; there was very little dust or mist above him.

  The G forces were reaching their peak now—constant thrust combined with reducing aircraft mass to drive the acceleration higher—he was almost up to four G. This wasn’t excessive, Deeke knew, but it hurt his aging chest; he felt he had to fight to take a breath.

  “Stand by for shutdown.”

  “Standing by.”

  The airframe popped and banged, its skin panels buckling and cracking as he climbed through four G. He’d heard such noises before. The pilots used to call it the oil-can effect. Outside air would work its way into the aircraft through small gaps in external doors or panels; the air was like a torch at high speeds, and would burn electrical wiring, aluminum internal structure and metal tubing, and smoke would waft into the cockpit.

  But the X-15, even after decades in a museum, was a tough old bird.

  A minute twenty-three. Deeke closed the shutdown switch.

  The roar of the engine tailed off into a high-pitched, hog-calling squeal, then ceased.

  Suddenly he was weightless; he was thrown forward against his restraints, and he felt his stomach lurch within him.

  He was gliding, at almost five Mach, a stone hurled from a catapult.

  Now Deeke took his left-side stick, to work the RCS manual controls. He dipped the nose of the X-15.

  The horizon rose over the lip of the mailbox window before him. My God, he thought. I’m too damn old for this.

  Earth was a brilliant blue floor beneath him, set beneath a darkened sky. To his left and right, he could make out the whole of the eastern seaboard of the U.S., from New York bay to his left, Florida obscured by its ragged coating of cloud below him, and to his right, set in the glittering blue skin of the ocean, a lumpy, brown-green mass that must be Cuba. He was still climbing, thrown by the rocket thrust out of the atmosphere like a stone. The curvature of the planet was clearly visible, as was the layer of denser atmosphere that surrounded it.

  And, directly ahead of him, a pillar of orange-white vapor came climbing out of the atmosphere, filled with bright sunlight, arcing gracefully away from him. At the tip of the pillar there was a jewel of yellow-white light, a droplet of brilliance brighter than the sun itself.

  The stark simplicity of that thrust out of gravity’s bonds was unbearably beautiful, astonishing, like a direct challenge to God.

  Through gaps in the cloud Jackie could see the solid rockets fall away from the stack, still trailing dribbles of smoke and flame. The
re was a ragged cheer from the stand behind her.

  Once started, the solid rockets couldn’t be stopped or throttled down, unlike liquid boosters; once the solids were lit, the orbiter—and its crew and that huge explosive tank of hydrogen and oxygen strapped to its belly—were just along for the ride, until the SRBs expended themselves.

  So getting rid of the SRBs was a good sign. And—

  And suddenly there was a second contrail in the sky, spider-web thin, climbing up from the southwest.

  She heard some muttering from the press stand behind her. “What the hell can that be? A chase plane?”

  But there were no chase planes during a launch. The whole area was supposed to be kept clear.

  It was difficult to follow the track, through the breaks in the cloud deck. But it looked to Jackie’s inexpert eye as if that second trail was heading straight for the climbing Shuttle stack.

  “NASA have confirmed SRB sep, Linebacker.”

  “Rog.”

  At this point in its ascent profile Endeavour was climbing towards Mach Four, Deeke knew—but even so the X- 15 was outrunning it. It was the only aircraft in the world which could have done so.

  Now there was one more decision point, one more gate to pass through.

  It took one more second for the confirmation to come.

  “Linebacker, you are go to deploy. Repeat, go to deploy.”

  The pure oxygen in his helmet seemed to have turned his mouth dry as Mojave dust.

  “Linebacker, do you copy? You are go to deploy.”

  “… Affirm, Canaveral. Copy that. Go to deploy.”

  There was one major addition to the X-15 control panel, a small flip-up softscreen display. Deeke reached forward and lifted this now. It showed a schematic gunsight, and a bright starburst, representing the Shuttle, over to the left of the screen.

  He took the RCS control in his left hand. The reaction control system was a set of simple hydrogen peroxide rockets. Deeke used the system in bang-bang mode, where he just pulsed the RCS rockets by shoving at the control stick. When he didn’t get the response he wanted, he applied another impulse. And he took care to move in just one axis at a time, to keep control.

  In stages, blipping his RCS, he turned the nose of the X-15 as it soared through its ballistic profile. All Deeke had to do now was to center the Shuttle starburst in the little toy gunsight.

  Point and shoot.

  After a couple of minutes, still closing on Endeavour, he got the starburst centered.

  It was a firing solution.

  The digital display came up with a small qwerty keypad, for him to punch in an enabling code.

  He held his gloved hand over the pad.

  His whole life hung on this moment, the actions he took in the next few seconds.

  Somehow, although he’d rehearsed it, in simulations and in his head, he’d never quite believed he’d have to face this. All he’d really wanted was a way to get back into the cockpit of an X-15, one last time, before he subsided into old age.

  “Canaveral. Do I still have go for deploy?”

  “Linebacker, you have go for deploy. Repeat—”

  “Affirm.”

  He thought of the blank faces of the ground crew and suit techs, of Hartle sitting like a spider in its web at the heart of Cheyenne.

  What right did Deeke have to entertain doubts? What right did he have to oppose such certainty?

  His hesitation melted away. He tapped in the code with confident keystrokes. He could barely feel the pad through his thick gloves.

  He felt a solid clunk beneath him. That would be the pyrotechnic bolts severing the ASAT from its berth in the belly of the X-15, and pushing it away.

  It was done.

  For a moment he heard and felt nothing else. The X-15 continued to arc upward through its ballistic profile, climbing towards its peak altitude of two hundred thousand feet. His attitude was drifting off a little; he would have to correct it…

  There was a burst of yellow-white light beneath him.

  He could see a slim pencil, trailing a blob of fire and billowing smoke, white and clean, like the smoke from the Shuttle’s own solid rocket boosters.

  Deeke corrected his attitude drift with blips from his RCS. He lifted his nose, so that the horizon was hidden by the sill of his window. He didn’t particularly want to witness the last act of this drama, when it came.

  He closed up the little digital pad; it had served its purpose, and had no further function.

  The ASAT arced away from him, towards the sunlit horizon, over the lumpy cloud.

  “Smooth as glass, Houston. To software mode 103…”

  With the solid boosters discarded, Endeavour was driven upward solely by her main engines, the External Tank feeding propellants through its connecting pipes. The ride became easier; liquid boosters provided a much smoother thrust than solids. The whole stack seemed to purr, like some huge sewing machine, every part working in harmony with the rest.

  Benacerraf found herself grinning, the exhilaration of the launch getting to her.

  Way to go, she thought. Way to go.

  The ASAT, developed by Boeing in the Reagan years, had been in storage for two decades.

  Now, called upon at last, it functioned perfectly.

  It was actually a three-stage solid-propellant rocket. It controlled its attitude using three large movable fins on its tail. It carried an infrared sensor and eight small telescopes to help locate its target. It was intelligent, to some degree, containing an on-board computer and a laser gyro.

  The first stage fell away, and the smaller second stage burned briefly, accelerating the ASAT to many multiples of the speed of sound.

  Then the second stage was discarded.

  The ASAT was designed for airborne launch, primarily from an F-15, and was actually capable of knocking satellites out of low Earth orbit. So it was overdesigned for this particular mission. That was not seen as a problem, by the mission planners.

  The final stage of the ASAT was basically a smart projectile, which would use the momentum imparted by the rocket boosters to hurl itself at its target. It spun itself up now, and used the fifty-six small rockets in its outer hull to obey its guidance system and keep it on its course. It carried no explosive; it was designed to destroy its target by direct collision, impacting with the force of a shell from a battleship’s main gun.

  It closed rapidly on the infrared glow it perceived before it. But the target was large, complex, with many sources of heat; accuracy would be difficult to achieve.

  There was a bang: loud, deep, solid.

  The flight deck shuddered, over and above the usual rattling of equipment and loose gear.

  Benacerraf was startled. She remembered nothing like this from the sims, or her first flight.

  Libet turned to Angel, her mouth open. “What was that?”

  Marcus White called up with a routine message. “Endeavour, you have two-engine transatlantic abort capability.”

  Angel said, “Copy, two-engine TAL.” His voice was flat, the response automatic; Benacerraf could see that his attention was focused on a main engine status display. “Houston, Endeavour. I think we might have a situation here. I’m reading a climb in the fuel pump operating temperature, on main engine number one.”

  “Endeavour, Houston. Say again.”

  “I have a multisensor fuel pump temp rise on engine one.”

  “Copy that, Endeavour. Stand by…”

  Tell me this isn’t happening, Barbara Fahy thought.

  In her mind she replayed those final, stunning pictures from the big FCR screens, over and over again: the remote, blurred image of the Shuttle stack still rising smoothly, with the SRBs slowly diverging—and then that shocking incursion from the edge of the picture, a second contrail that had cut obliquely across the complex shape of the orbiter.

  Some asshole shot at us.

  I still can’t believe this is happening, she thought. Who the hell would try to shoot down a Space Shutt
le? The Chinese, maybe?

  The controller called Booster was trying to get her attention. “Flight, Booster. Flight.”

  She tried to reply; she felt her mouth working, but no sound emerged, as if the components of her body were becoming disengaged, the systems breaking down.

  At last she forced out a word. “Go.”

  “Confirm that temperature rise in the center engine. If we pass through nine hundred fifty we’re heading for an auto shutdown. We’re working on the hypothesis that there’s been a collision of some kind, probably with one of the discarded SRB s. We—”

  “No. Booster, that’s wrong.”

  “But—”

  Somehow it made it easier for her that she wasn’t the only one, here, who couldn’t believe this. “We all saw it, damn it. Someone just drove into us. We’ve been hit a glancing blow by some kind of projectile. Prop, Egil, DPS, are you working with Booster on this?”

  “Confirm, Flight.”

  “Flight, capcom. What do I tell the crew?”

  She took a breath. “Stand by, Marcus. Let’s just keep monitoring. We haven’t lost anything yet; we still have all three engines.”

  But, she wondered, for how long?

  To Benacerraf, it was like a rerun of the disintegration of Columbia’s final mission, the slow, almost laborious unraveling of catastrophe. Not again, she thought. Dear God, whatever happens, I can’t go through that again.

  Angel turned to Libet, and Benacerraf could see him clench a fist, big knuckles white. “Houston, we heard a bang, just after SRB sep. A loud bang. We have a real issue here.” His voice had a sharp edge.

  “We’re working on it, Bill,” Marcus White said. “Four minutes twenty. You have negative return. Do you copy?”

  That routine call meant that, whatever the emergency, the abort option of returning to the launch site—in a drastic powered maneuver that would have pointed the Shuttle back towards Canaveral and used its main engines to slow it—was no longer available.

  And it was a reminder that the events of the launch were continuing around them, bang or no bang; that Benacerraf was still trapped here, inside this slowly exploding bomb.

  Angel said, “I Houston, I’m watching this damn engine temperature reading here. It’s still climbing. Over nine twenty degrees—”