Titan n-2

by Stephen Baxter

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

  “We’re copying, Endeavour, Hold on that. Endeavour, Houston. Negative TAL now.”

  “Copy, negative TAL.”

  Another abort option had passed out of operation. Now it was impossible for the orbiter to attempt to cross the Atlantic and land at the emergency airstrip, at Zaragoza in Spain.

  “Four minutes fifty seconds,” White said. “We’re still with you guys.”

  Despite the situation, his tone was even, deep, immensely reassuring to Benacerraf. This is a man who has been to the Moon, she thought. Marcus won’t feed us bullshit. He will make sure we’re okay.

  Angel was hunched forward, against the acceleration, studying his main engine temperature gauge.

  If only, she thought, White was here in the cabin with them.

  Angel said, “Okay, the center engine has gone through its red line. Do you copy? Nine hundred fifty centigrade. And—”

  Benacerraf felt an immediate decrease of acceleration, a lessening of the Gs that pressed her against her seat. The flight deck was filled with a loud, oscillating tone. Four big red push-button alarm lights lit up on the instrument panels around the cabin.

  Angel pushed a glowing button on a central panel, above a CRT, to kill the alarm. “Master alarm,” he snapped.

  I know, Benacerraf thought bleakly.

  Just to the right of the lowest of the cockpit’s three CRT screens was a small cluster of three lights. They were main engine status lights. Benacerraf saw that the centermost light had turned red.

  “We lost the center engine,” Angel called. “It got too hot and shut itself down.”

  “We copy, Endeavour,” Marcus White said. “Endeavour, Houston…” The capcom fell silent.

  “We’re waiting,” Angel said heavily.

  Deeke tried to keep from looking out of the cockpit.

  What would he see? — a cloud of dispersing liquid oxygen from a ruptured External Tank, the bright orange glow of RCS hypergolics, fragments of the orbiter wheeling out of the plume, like another Challenger?

  Had it worked?

  …He approached his peak altitude. Deeke began to push his nose down, with RCS blips, so that he climbed to the top with a ten-degree nose-down attitude.

  In the moment of stasis at the top of his trajectory, he saw the Earth, spread out before him, through his mailbox window.

  The world was very bright, like an inverted sky. Under the nose of the aircraft it curved away, in all directions, as if he were poised above some huge blue dome. Out ahead, he could see the ocean, a deeper, bluish grey color. The atmosphere was clearly visible, as a layer of blue haze over the Earth. Above him there was only blackness.

  It was extraordinarily beautiful.

  My God, he thought. What have I done?

  He probed his soul for remorse.

  His main regret, actually, was that he would surely, in any conceivable future, never again fly like this, never see the Earth from this extraordinary altitude, spread out like a bright blue quilt.

  As he went over the top, the change was rapid; the flight path changed from a climb of plus thirty degrees to minus thirty in minutes.

  The deep ocean receded from him as he fell. The lighter blue of the coastal waters expanded below him, coated with lumpy cloud. The air seemed to reach up and clutch at him.

  The black nose of the X-15 began to glow as the plane dipped back into the thickening atmosphere. The sensation of speed returned, and negative Gs piled on, soon climbing to four or five.

  Deeke pulled X-15 up through twenty degrees. He could feel the aircraft fighting him. The leading edges of the wings glowed a bright cherry-red; now, at the climax of the reentry, the heat of air friction was dispersing around the airframe, raising its average temperature above a thousand degrees. But here, in his little aluminum shell, Deeke could feel nothing but the brutal eyeballs-out deceleration. He felt blood pool in his arms, painfully.

  Canaveral said, “Ease it on over. Watch your nose position, Linebacker. We have you low on altitude. Bring it back up. Pull your nose on up, Linebacker.”

  “Okay, it’s coming up.”

  “Turn left three degrees. Left three degrees.”

  “Rog.”

  “Speed brakes in. And maintain your altitude, you’re still a little low, Linebacker.”

  “Rog.”

  “Okay, you’re about ten miles from your checkpoint. You’re looking very good here, Linebacker.”

  The calm, competent dialogue went on, routine and almost meaningless.

  Nobody had said a word since he’d deployed the ASAT. He still didn’t know whether he’d succeeded or not.

  Just get onto the ground, Linebacker. Time enough for all that later.

  The flight dynamics engineer, Fido, was talking steadily in Fahy’s ear, outlining available abort modes to her.

  The RTLS and TAL modes were already unavailable to her. But they could lengthen the burn of the remaining engines and the OMS, and so reach some kind of orbit. Tha
t was an Abort to Orbit, ATO. It had actually been flown before. Later, an abort once-around would be available, with Endeavour completing a single circuit of Earth, and reentering immediately.

  The ATO gave some chance of salvaging some of the mission’s objectives. And getting Endeavour up, intact, into some kind of orbit would provide time to figure out what in hell was going on here, and what resources she had to work with.

  But an ATO would be a gamble. She would have to hope that the remaining main engines kept working nominally for the rest of the ascent. And as Booster kept pointing out, there was no guarantee of that.

  Someone shot at us, damn it. I can’t believe it.

  The launch sequence was unfolding rapidly, a ticking clock. In the next few seconds, she had to make the decision: to abort or not, and which mode.

  Again that strange feeling of decoupling settled over her, as if she was paralysed by her anxiety, as if she could no longer make her body function in conjunction with her will. She wanted to just sit here, listening to GNC’s brisk voice outlining the technical options.

  It’s as if I was hit by that damn missile, whatever it was, rather than the Shuttle. We’re all just flawed, limited beings, struggling to cope with these monstrous machines we create, and failing.

  I can’t do this any more, she thought.

  But I must.

  She thought about her assets. After all, the Shuttle’s main engines were the most complicated ever built. They were throttleable, and had to deliver high thrust with great efficiency. They had inbuilt control systems, so they could monitor their own performance. They were heavily over-engineered, made to be rugged for multiple reuse. Each of the engines on Endeavour today had flown a dozen or more times before, on different orbiters, running up thousands of seconds of hot-fire time each.

  The hell with it, she thought. Those engines are tough. No asshole is going to shoot us down. Especially as they all but missed.

  She felt determination gathering in her, dispelling her doubts.

  She turned to Marcus White, her capcom.

  When White came back on the loop, he sounded more decisive.

  “Endeavour,Houston. Abort to orbit.”

  Angel glanced at Libet. “Say again, Marcus.”

  “Endeavour,Houston. We’re going to abort to orbit, Bill.”

  “About fucking time,” Angel said.

  He reached down to a small panel close to his right hand, and turned a rotary switch from OFF to its extreme right position, ATO. Then, on the same panel, he pushed a button to confirm the abort. Now they had a course of action ahead, Angel looked as if he was actually enjoying this, as if he was already thinking ahead to the sea stories he could spin out of it.

  He was one unimaginative asshole, Benacerraf thought angrily. And yet right now, her life was in his hands…

  “Uh-oh,” Libet said.

  “What? What now?”

  “I got temperature rises in the remaining main engines.”

  “Which one?”

  “Both of them, Bill. Look here.”

  “Oh, shit.”

  Benacerraf tried to remember what the procedure would be if they lost another main engine now. She had a sinking feeling that there wasn’t one.

  Is this how, after all, human spaceflight is to finish, for the foreseeable future?

  Beyond the pilot’s windows, the sky was growing dark.

  “Endeavour,Houston. We copy your temperature rises, Bill. Here’s what you have to do. We want you to override the main engine auto shutdown.”

  “Say again.”

  “Override the shutdown. Don’t let the engines shut themselves off.”

  Angel and Libet hesitated for one second. Then they began to work switches.

  The first engine had shut itself off when its internal multisensor noted the pump operating temperature exceeding its safety limit. Perhaps Mission Control were speculating that the readings were flaky, that identical temperature rises in the other pumps were unlikely. If that was so, then a well-meant auto shutdown of a perfectly functioning engine might be the greatest hazard facing the crew.

  On the other hand, if the sensor readings were not ratty — if the operating temperatures in those pumps really was rising as the data showed — then probably, before they reached orbit, one of the pumps would blow itself to pieces. And that would finish Endeavour anyhow.

  After all, they had all heard and felt that bang. There was more than just a telemetry problem here.

  Fahy, Benacerraf sensed, was taking a hell of a gamble.

  Maybe she is compensating, still, for what happened with Columbia. Even overcompensating.

  But what choice do I have but to trust her?

  “Okay, Houston, Endeavour. Auto shutdown disabled. Now what?”

  “Endeavour,we’re going to ask you to burn your remaining two main engines for an extra forty-nine seconds. And the OMS one burn will be extended. And augmented with an aft RCS burn. Do you copy all that?”

  Benacerraf had scribbled down the instructions on a scratchpad. “Forty-nine seconds, then an extended OMS. We have that, Houston.”

  Meanwhile the orbiter continued its climb.

  They were eighty miles high, and moving at Mach fifteen.

  Now Benacerraf felt the orbiter pitch further over, almost onto its back.

  “Okay,” Angel said, “we have single engine press to ATO. Houston, Endeavour. Single engine press to ATO.”

  “Copy that, Endeavour. We’re breathing a little easier down here.”

  “Keep your pacemaker charged up, Marcus.”

  Another barrier had been passed. Now, even if another main engine failed, the Shuttle could still continue to MECO — main engine cut-off — with one engine, and so, presumably, achieve some kind of orbit, even if lower than planned.

  Benacerraf knew that the risk of catastrophic failure had receded a little.

  “Main engine throttle down.”

  “Throttle down, copy.”

  “Seven minutes forty. Endeavour, Houston. Engines down to sixty-five percent. You’re looking good.”

  “Sure we are.”

  She could see a muscle ticking in Angel’s cheek. He was itching to do something, she saw. The launch sequence was so automated that there was almost nothing the crew could do to influence events. They could only sit here, gripping checklists and seat frames, wait while some piece of abort-procedure software flew the craft, hope that nobody had screwed up. No wonder the astronauts had always fought to retain control systems in their ships. Inactivity drove them rapidly crazy.

  “Eight minutes thirty-eight,” Angel said. “Okay, people. Now we’re in the extended thrust regime. Here we go…”

  According to the original timeline, MECO should have come at eight thirty-eight. They were off the flight profile, then.

  “Endeavour,Houston. Coming up on MECO at revised time of nine minutes twenty-seven.”

  “Copy that, Marcus.”

  “At this time you are go for MECO.”

  “We’re relieved to hear it.”

  “Coming up on MECO, on my mark.”

  As the tanks emptied, the acceleration built up to its dynamic crescendo, shoving Benacerraf harder back in her seat.

  “Three, two, one. Mark.”

  The acceleration faded immediately.

  Benacerraf was not thrown forward. The force which had pressed her back simply vanished.

  She still had a sensation of motion, of high velocity, as if she could feel the huge energy which had been invested in her body and the rest of the orbiter’s mass.

  Her arms, limp, floated up from her lap before her.

  “MECO on schedule,” Angel said. “Houston, Endeavour. I got me three red engine status lights.” He turned and grinned through his faceplate at Benacerraf. “Those balky main engines can’t hurt us now.”

  “Endeavour,Houston. Bill, you are go for ET separation. On my mark. Three, two, one. Mark.”

  There was a remote boom.

 
“ET sep is good,” Angel said. “Beginning minus zee translation.”

  “Paula,” Libet said. She pointed upwards. “Look out there.”

  The orbiter, without its External Tank, was still flying upside down, almost parallel to the Earth’s surface. So when Benacerraf squinted upwards, she could see the blue skin of the Indian Ocean.

  And there, dark and ugly against the ocean, was the bullet shape of the External Tank. The brown insulation foam over its aluminum-lithium lightweight honeycomb shell was battered and badly charred, by the air friction of the ascent and rocket exhausts. It would fall back into the atmosphere to a height of a hundred and sixty thousand feet, where, glowing white hot, its fragments would hail down over an empty slice of Indian Ocean.

  “It looks more beat-up than I expected,” Benacerraf said.

  “Yes. Like it’s been in a war,” Libet said.

  “So it has.”

  “Software in mode 104,” Angel said.

  “Endeavour,Houston. You are go for the OMS-one burn.”

  “Copy that, go for OMS-one,” Angel said.

  Libet worked switches. “Attitude indicator to inertial.”

  Angel began to punch the relevant navigation software into the computer, using the keypad to his right. Benacerraf, still following her checklist, monitored his keystrokes: ITEM 27 EXEC.

  The small orbital maneuvering system lit up with a crisp jolt, a dull roar.

  “We’re going to come out of this low,” Libet said.

  She got no reply. There was silence, on the ground, on the flight deck.

  The burn seemed, to Benacerraf, to go on and on.

  White called from the ground, “Coming up on OMS cut-off. On my mark. Three, two, one. Mark.”

  The gentle thrust died.

  In the FCR there was a burst of clapping.

  Endeavour was in orbit.

  Barbara Fahy thumped her clenched fist against the surface of her workstation. She felt a surge of savage, exultant joy. She had acted; her decision had been correct, and had maybe saved the mission.

  She wished she could get her hands on whoever had shot at her orbiter. She felt she could destroy them herself, with her bare hands, unleashing primitive, savage energy.