Titan. Stephen Baxter

power and purging vehicles with their long, dangling umbilical hoses. There was a feeling of business, of competence, out there in the desert heat.

      To Hadamard, a city boy whose haunt was Washington, D.C., this was a bleak alien place, inhabited by incomprehensible machines; he might as well have been transported to Mars.

      There was a stir in the crowd around him.

      He looked around, seeking its source. Some of the grizzled old veteran-type astronauts were looking up at the PA stands, shielding their eyes against the low sun. The air-to-ground loop sounded a lot tenser than before, with a lot of chatter about orbiter components called APUs.

      Something, evidently, was going wrong.

      Despite the gathering warmth of the sun, he started to feel cold.

      He sure as hell didn’t want any major malfunctions showing up during this landing, or any other. It was a thought he hauled around with him constantly, during every one of these damn missions. As illogical as it might be, he knew he’d carry the can for any new Challenger-type débâcle.

      Not that he’d hesitate to take several others down with him.

      A couple of small, slim needle-nose jets went screaming overhead, heading up into the blue dome of the sky. They were T-38s. Hadamard knew that sending up chase planes like that wasn’t routine.

      He looked around for someone to explain to him what was happening.

      

      ‘What the hell happened to APU two, EGIL?’

      ‘I can’t tell yet, Flight.’

      ‘Are the other power units stable?’

      ‘I’m still looking at high temperatures back there.’

      ‘What does that mean?’

      ‘Maybe a fire, Flight. I can’t tell yet.’

      A fire, Fahy knew, would mean the orbiter could lose all three of its power units. Loss of power units at this point of the entry would put Columbia right in the middle of a non-survivable window in the mission profile: without the power units, without hydraulics, Columbia couldn’t work its aerosurfaces, and control its glide. Without the power units, Columbia would tumble and burn up.

      A fire would mean they would lose the orbiter.

      Jesus, she thought.

      Prop was coming up with a diagnosis of the OMS flame-out.

      ‘We’ve been studying the temperature rise in the fuel feeds, just before OMS loss. We figure we must have had a slug of hydrazine, frozen in there.’

      ‘How could that happen?’

      ‘Maybe during the EDO thermal tests … if we had a failed wraparound heater –’

      ‘Copy that.’ During the long hours in orbit, when the payload bay had been held in shadow – to test the extended-operations pallet’s tolerance to cold – maybe a little hydrazine had actually frozen in a fuel line, wrapped in a faulty heater, with no telemetry to indicate anything was wrong.

      ‘Then, when the burn came, and that slug heated up … The data’s chancy. The line might have exploded, Flight.’

      ‘What would that do?’

      ‘It would have gone off like a small grenade. It would have made a hell of a mess of the OMS engine pod. If the lines were ruptured, you’d have fuel and oxidizer sprayed all over that pod.’

      ‘But what about the second pod?’

      ‘Flight, there’s a crossfeed to take propellant from one pod to the other. We figure that’s how the fire crossed over. Maybe the slug was even in the crossfeed. There’s also a crossfeed to the RCS, from the OMS propellant tanks. We’re lucky we didn’t lose the RCS as well, before the burn was completed.’

      ‘Thank you.’

      ‘Flight, Egil. APU one and three temperatures still rising …’

      On it went. And now the surgeon started talking about the stress levels manifesting themselves in the biotelemetry from the orbiter. There wasn’t much Fahy could do about that, any more than she could manage down her own stress levels. And behind her, she could hear the MOD manager talking quietly into his microphone. The mission operations directorate manager was a link from the FCR to NASA and JSC senior management.

      It all continued to unravel.

      Fahy tried to get a handle on all of this, to make some decisions.

      None of her training, her experience, her orderly approach to contingency management, seemed to be helping her think her way through this. The problems here weren’t to do with her control, or with her team, but with the crummy technology which was falling apart in front of her. Even so, she was aware that she wasn’t handling this well, that Tom Lamb, with his fast decision to go for the reaction control burn, had actually achieved a lot more in this crisis than she had. With that action he might have saved the mission, in fact.

      Multiple failures would always get you; it was impossible to plan for every contingency.

      But maybe, she thought sourly, if the orbiter mission preparation process hadn’t been cut back to the bone, somebody might have caught this problem, before it blew up in their faces.

      The master alarm sounded again.

      

      Marcus White, Tom Lamb’s commander from his Apollo mission, was at JSC that day, for a Gemini fortieth anniversary dinner. When he heard what was going down over in Building 30, he came over fast. Now, he stood in the viewing gallery at the back of the FCR and watched as Barbara Fahy and her team of kids struggled to understand what was happening.

      Unlike Lamb, Marcus White had long since retired from NASA. After his Moon landing he was passed over for the Skylab missions and ASTP. He went into training for the Shuttle flights. But when the development delays started to hit, and the first flights were pushed back past the end of the 1970s, he got a little pissed off at kicking his heels around JSC.

      So he retired from NASA. At least his wife was pleased about that. He joined McDonnell Douglas out at Long Beach, and watched from outside as NASA and Rockwell between them royally screwed up the Space Shuttle program.

      If Columbia failed today, it would be a horror, but not a surprise, to Marcus White. He hated Shuttle; he always had. Its flaws went all the way back to the compromises that were involved in its design in the first place, back in the ’70s. You put solid rocket boosters on a manned ship, you’re going to get a Challenger. You turn your spacecraft into an unpowered glider for the entry, you’ll have this, a Columbia. His only regret was that now, in its final failure, Columbia might take Tom with it.

      

      Angel pushed the red button again. ‘APU temperature this time.’

      ‘There’s nothing we can do about that,’ Lamb said briskly. ‘Let’s position for entry.’ He grasped his control stick again, and pushed.

      Under the control of her RCS jets the orbiter somersaulted gracefully forward, briefly as graceful as a 2001 space clipper. Earth wheeled, the cabin light shifting, until the planet showed before the front windows.

      Columbia was facing forward now, her nose pitched up at an angle of about thirty degrees. Earth was spread out below the cockpit, a glowing blue carpet, subtly curved. The orbiter was the right way up, and descending.

      Suddenly, it started to feel like a landing to Benacerraf.

      ‘Houston, Columbia. We are in entry attitude.’

      ‘Copy that, Columbia. Looking good at this time. Are you ready for your entry switch checklist?’

      Lamb grinned at Angel. ‘Just like the other five times I’ve done this, Joe.’

      ‘I’m glad it’s you up there, Tom, if we’ve got to have a bad day.’

      ‘Wish