Gravity. Tess Gerritsen

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       2

      July 7

      Two Years Later

       Abort.

      Through the thunder of the solid propellant rocket boosters and the teeth-jarring rattle of the orbiter, the command abort sprang so clearly into Mission Specialist Emma Watson’s mind she might have heard it shouted through her comm unit. None of the crew had, in fact, said the word aloud, but in that instant she knew the choice had to be made, and quickly. She hadn’t heard the verdict yet from Commander Bob Kittredge or Pilot Jill Hewitt, seated in the cockpit in front of her. She didn’t need to. They had worked so long together as a team they could read each other’s minds, and the amber warning lights flashing on the shuttle’s flight console clearly dictated their next actions.

      Seconds before, Endeavour had reached Max Q, the point during launch of greatest aerodynamic stress, when the orbiter, thrusting against the resistance of the atmosphere, begins to shudder violently. Kittredge had briefly throttled back to seventy percent to ease the vibrations. Now the console warning lights told them they’d lost two of their three main engines. Even with one main engine and two solid rocket boosters still firing, they would never make it to orbit.

      They had to abort the launch.

      ‘Control, this is Endeavour,’ said Kittredge, his voice crisp and steady. Not a hint of apprehension. ‘Unable to throttle up. Left and center MEs* went out at Max Q. We are stuck in the bucket. Going to RTLS abort.’

‘Roger, Endeavour. We confirm two MEs^* out. Proceed to RTLS abort after SRB burnout.’

      Emma was already rifling through the stack of checklists, and she retrieved the card for ‘Return to Launch Site Abort.’ The crew knew every step of the procedure by heart, but in the frantic pace of an emergency abort, some vital action might be forgotten. The checklist was their security blanket.

      Her heart racing, Emma scanned the appropriate path of action, clearly marked in blue. A two-engine-down RTLS abort was survivable—but only theoretically. A sequence of near miracles had to happen next. First they had to dump fuel and cut off the last main engine before separating from the huge external fuel tank. Then Kittredge would pitch the orbiter around to a heads-up attitude, pointing back toward the launch site. He would have one chance, and only one, to guide them to a safe touchdown at Kennedy. A single mistake would send Endeavour plunging into the sea.

      Their lives were now in the hands of Commander Kittredge.

      His voice, in constant communication with Mission Control, still sounded steady, even a little bored, as they approached the two-minute mark. The next crisis point. The CRT display flashed the Pc<50 signal. The solid rocket boosters were burning out, on schedule.

      Emma felt it at once, the startling deceleration as the boosters consumed the last of the fuel. Then a brilliant flash of light in the window made her squint as the SRBs exploded away from the tank.

      The roar of launch fell ominously silent, the violent shudder calming to a smooth, almost tranquil ride. In the abrupt calm, she was aware of her own pulse accelerating, her heart thudding like a fist against her chest restraint.

      ‘Control, this is Endeavour,’ said Kittredge, still unnaturally calm. ‘We have SRB sep.’

      ‘Roger, we see it.’

      ‘Initiating abort.’ Kittredge depressed the Abort push button, the rotary switch already positioned at the RTLS option.

      Over her comm unit, Emma heard Jill Hewitt call out, ‘Emma, let’s hear the checklist!’

      ‘I’ve got it.’ Emma began to read aloud, and the sound of her own voice was as startlingly calm as Kittredge’s and Hewitt’s. Anyone listening to their dialogue would never have guessed they faced catastrophe. They had assumed machine mode, their panic suppressed, every action guided by rote memory and training. Their onboard computers would automatically set their return course. They were continuing downrange, still climbing to four hundred thousand feet as they dissipated fuel.

      Now she felt the dizzying spin as the orbiter began its pitch-around maneuver, rolling tail over nose. The horizon, which had been upside down, suddenly righted itself as they turned back toward Kennedy, almost four hundred miles away.

      ‘Endeavour, this is Control. Go for main engine cutoff.’

      ‘Roger,’ responded Kittredge. ‘MECO now.’

      On the instrument panel, the three engine status indicators suddenly flashed red. He had shut off the main engines, and in twenty seconds, the external fuel tank would drop away into the sea.

      Altitude dropping fast, thought Emma. But we’re headed for home.

      She gave a start. A warning buzzed, and new panel lights flashed on the console.

      ‘Control, we’ve lost computer number three!’ cried Hewitt. ‘We have lost a nav-state vector! Repeat, we’ve lost a nav-state vector!’

      ‘It could be an inertial-measurement malf,’ said Andy Mercer, the other mission specialist seated beside Emma. ‘Take it off-line.’

      ‘No! It might be a broken data bus!’ cut in Emma. ‘I say we engage the backup.’

      ‘Agreed,’ snapped Kittredge.

      ‘Going to backup,’ said Hewitt. She switched to computer number five.

      The vector reappeared. Everyone heaved a sigh of relief.

      The burst of explosive charges signaled the separation of the empty fuel tank. They couldn’t see it fall away into the sea, but they knew another crisis point had just passed. The orbiter was flying free now, a fat and awkward bird gliding homeward.

      Hewitt barked, ‘Shit! We’ve lost an APU!’

      Emma’s chin jerked up as a new buzzer sounded. An auxiliary power unit was out. Then another alarm screamed, and her gaze flew in panic to the consoles. A multitude of amber warning lights were flashing. On the video screens, all the data had vanished. Instead there were only ominous black and white stripes. A catastrophic computer failure. They were flying without navigation data. Without flap control.

      ‘Andy and I are on the APU malf!’ yelled Emma.

      ‘Reengage backup!’

      Hewitt flicked the switch and cursed. ‘I’m getting no joy, guys. Nothing’s happening—’

      ‘Do it again!’

      ‘Still not reengaging.’

      ‘She’s СКАЧАТЬ