found she was gripping her checklist so hard her fingers hurt.
Is that it? Is it over?
The master alarm sounded, jarring.
More lights appeared on the caution/warning array, and on another display to Angel’s right hand. Lamb killed the alarm.
‘Uh oh,’ said Angel. ‘There goes power unit two.’
The capcom said, ‘Copy that, Columbia. We confirm, APU two down.’
Lamb said evenly, ‘Well, we still have two out of three APUs up and running, so we’re still nominal.’ But Benacerraf thought she could see something in the set of his shoulders.
The auxiliary power units sat in back of the orbiter, close to the OMS engine pods. And they already knew something serious had happened back in that part of the ship. Lamb, she sensed, was starting to fear that the problem back there, whatever it was, might be spreading.
The cabin darkened; Columbia had flown for the last time into the shadow of Earth.
Hadamard took his seat on the podium for NASA officers, astronauts and guests, at the end of the press line. The PA was intoning the usual incomprehensible timeline technicalities, mixed in with the crackle of air-to-ground loops. A bunch of Morton Thiokol executives came to sit with Hadamard; they were clutching their blank commemorative stamp covers, that they could get stamped at the Base post office later. Everybody loved spaceships and astronaut pilot heroes, even these crusty aerospace types. Hadamard felt sour.
A plane, sleek and white, flew low over the landing site. Hadamard recognized it; it was a Shuttle Training Aircraft, a modified Grumman Gulfstream executive jet with a computer on board that modified the plane’s handling characteristics so that the astronauts could train for the orbiter’s unique landing approach. There used to be two STAs; Hadamard had cut one, soon after he got his job. It was a waste of money. There just wasn’t the demand for that many new Shuttle pilots.
He looked out over the landing site.
The lake bed was a plain of dried-out, cracked mud, stretching all the way to the mountains that shouldered over the horizon. The runway was just painted on the surface, as simple as that. It was fifteen thousand feet long, twice as long and wide as most commercial runways, with a five-mile overrun stretching off into the lake bed. Hadamard could see a team working its way along the runway on foot, looking out for foreign objects that might have settled there. Where the desert mud had been scuffed by feet and tyres, it had turned to a fine powder that blew in the soft breeze across the press stands; Hadamard could see it settling on his patent leather shoes.
Beyond the runway Hadamard recognized the big blocky gantry of the mate-demate device, that would lift the orbiter onto its transport aircraft for the trip back to the Cape. It looked like some huge car-wash. A recovery convoy had gathered in a parking area, within sight of the runway. There was a big white-painted fire-tender in the middle of it all, and towing tractors, and a vapour dispersal truck with its big blowers, and there were the ground 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
