“Maybe so. What do you say?”

“Why now? I mean, it’s not going to make a damn piece of difference to the way we live our lives, the extent to which we see each other. You’re not going to give up your career.”

“Of course not, and neither are you.” She pulled at his fingers. “But that’s not the point.”

Then what is, Natalie? What primeval instinct has dragged this up, after all this time? And right at this moment, when you’re thinking of getting on a road that could take you off the Earth altogether…

She surely hadn’t come to terms with what had happened last night, yet.

Maybe this — tonight, with Mike — was all just some kind of way of dealing with Ben, she thought bleakly.

But if that was true, where did it leave her and Mike?…

Christ. What a mess.

The phone rang, its sharp tone startling her.

“Jesus.” He reached out and took the receiver. “Hello?… All right, I’ll be there.” He put the phone down.

“Mike—”

He was already halfway out of bed; he scrabbled over the floor, looking for his pants. “The burn was another failure. Sustained for less than half a second. Shit.” He touched her hair. “I’ve got to be there, Natalie. You go back to sleep.”

“I haven’t been asleep.” She kicked away the sheets and stood up; the air in the room was distinctly cold. “I’ll come, too.”

“You don’t have to.”

“I’d prefer it. Anyway, we have a conversation to finish.”

Mike had already pulled on his shirt; he was muttering to himself, as his mind started to whirl around the problems of the engine.

He’s probably already forgotten what we were talking about.

They set off for me test facility a little after 3 A.M. It was going to take half an hour to drive out to Santa Susana from downtown L.A.

Mike drove out of the San Fernando Valley, and York could see streetlights glowing down there, neat rectangular blocks of light plastered over the valley floor and walls.

Mike drove anxiously, too quickly, without speaking to her.

The test facility was nestled in a rough, boulder-strewn depression in the Santa Susana Mountains. When Mike stopped the car, she was struck by the chill of the air.

She walked with Mike to the center of the facility.

The stars were out overhead, though the young Moon had long set.

Santa Susana was operated on behalf of NASA by Rockwell International. It had been built as part of the development program for the old S-II, the Saturn V second stage. There was still some S-II development work going on there, in fact. The whole site was a swarm of activity, with technicians — some of them in flameproof or radiationproof gear — crawling all over the rig. To York, they looked like ungainly insects.

The NERVA 2 engine stood upended at the heart of the facility, surrounded by a wire-mesh safety fence. Glowing in powerful floodlights, the broad engine bell flared toward the sky.

When they got close to the rig, technicians came up to Conlig. Mike managed one last, apologetic glance back at York, and then he was lost.

Alone, she began to walk slowly around the rig.

“Hi. You look like you need this.”

She turned. A man was at her elbow, grinning; he was tall, pale, with blond hair; he wore grimy coveralls. He looked as if he had been up all night. He bore two plastic cups of a brownish liquid. “It’s from a dispenser. It’s supposed to be coffee,” he said, “but I wouldn’t bank on it without a full chemical analysis.”

“I know you. Don’t I?”

“Yup. Adam Bleeker. We took a field trip together a few years back, in the San Gabriel Mountains.”

“Oh.” The Cold Warrior astronaut. “With Ben and Charles Jones. What a disaster that was.”

“Oh, I wouldn’t say that. You did your job well. And everyone calls him Chuck, by the way.”

“Whatever.”

She took the coffee gratefully and sipped it. It was warm, but almost flavorless.

Bleeker told her he was the Astronaut Office representative on the project there. Ben Priest had covered the same assignment some years before.

“It’s kind of an odd time of day to run an engine test,” York observed.

“Well, we’re so far behind schedule. Every hour counts.”

“Tell me about it. I came out with Mike. Do you know him? — Mike Conlig—”

“Sure.”

“Nothing was going to keep him away from here, once the call came.”

They started to walk around the test rig, slowly. Technicians were everywhere, arguing desultorily. There was an almost tangible air of tension, of depression; it was Mike’s mood writ large.

The contrast to Jackass Flats — to the raw enthusiasm Mike had represented to her there — was marked.

In the middle of it all, the huge NERVA 2 engine stood erect and silent, aloof, remote behind its safety cordon. That motor, Mike had told her, was the “Integrated Subsystems Test Bed Engine”; it was a complete, more or less operational machine, but it was trapped in that ungainly test rig, and, when it fired, it could only drive itself into the solid Earth.

Just looking at the rig, York could tell that NERVA was still years away from flight status, from delivering its promised two hundred thousand pounds of interplanetary thrust.

The upturned nozzle sat atop a short, fat cylinder, and two smaller bells protruded from the cylinder’s sides. The cylinder was the pressure shell which contained the radioactive core, and the smaller nozzles, gimbaled, were attitude control rockets. She saw the ring of cone-shaped actuators at the base of the engine; the actuators operated the control drum, which moderated the reactor. A huge spherical hydrogen tank sat close to the engine, and pipes snaked from it to swaddle the pressure shell and nozzle. Plumes of vapor vented from the tank, and sheets of ice encrusted its sleek metal walls.

Adam Bleeker helped her trace out the engine’s operation.

“Liquid hydrogen works as both propellant and coolant — it’s called regenerative cooling. A pump pushes the hydrogen through that cooling jacket surrounding the pressure shell and the bell. Then the hydrogen is forced through the radioactive core, where it flashes to vapor, and drives its way out through the bell…”

There was still no trap for the vented hydrogen, York noted absently.

Bleeker showed her how an efflux pipe from the reactor carried a proportion of the hot hydrogen gas to a turbine, to power the engine’s pumps in flight. The turbopump exhaust was used as attitude control gas, vented off through the small supplementary nozzles.

“What’s the problem tonight?”

“Cavitation. Gas bubbles in the liquid hydrogen flow. We raised the core temperature to its working regime, and we’d started the hydrogen flow. We reached nominal thrust, for about half a second. But then the core temperature started to climb. We were cavitating, somewhere below the pump: hydrogen bubbles, stopping the circulation of coolant. And that was why the core temperature was climbing. We had to shut down.” He sounded tired. “You can imagine the safety restrictions we’re under here. If the pressure shell had been breached, we’d have had radioactive products reaching the atmosphere, and there would have been hell to pay. So as soon as we saw the problem, we had to obey the rule book, which said to shut off the hydrogen, and flood the whole damn core with water to ensure the temperature comes down. Now we’re going to have to siphon off all that radioactive water, and take the core apart by remotes, and make sure the propellant flow cylinders haven’t been damaged in the heat… It will be days before we’re set for the next test.”

“Christ. What a mess.”

York studied his profile; picked out by the powerful floods, Bleeker’s skin looked thin, almost translucent. She found it hard to read Bleeker’s own reaction to all this. Was he impatient at the restrictive rules, the need for safety? Did he have any qualms about handling lethal substances in such an unstable, unproven rig? She couldn’t tell. Just as when she’d first met him, Bleeker struck her as utterly calm, cool. Or, perhaps, completely without a soul.