“I suppose we could go on turning up the juice until we burned the thing out,” he said, “but that would prove nothing. What do you make of it?”
“Hal’s internal fault predictor could have made a mistake.”
“It’s more likely that our test rig has slipped up. Anyway, better safe than sorry. It’s just as well that we replaced the unit, if there’s the slightest doubt.”
Bowman unclipped the wafer of circuitry, and held it up to the light. The partly translucent material was veined with an intricate network of wiring and spotted with dimly visible microcomponents, so that it looked like some piece of abstract art.
“We can’t take any chances – after all, this is our link with Earth. I’ll file it as N/G and drop it in the junk store. Someone else can worry about it, when we get home.”
But the worrying was to start long before that, with the next transmission from Earth.
“X-ray-Delta-One, this is Mission Control, reference our two-one-five-five. We appear to have a slight problem.
“Your report that there is nothing wrong with the Alpha Echo three five unit agrees with our diagnosis. The fault could lie in the associated antenna circuits, but if so that should be apparent from other tests.
“There is a third possibility, which may be more serious. Your computer may have made an error in predicting the fault. Both our own nine-triple-zeros agree in suggesting this, on the basis of their information. This is not necessarily cause for alarm, in view of the back-up systems we have, but we would like you to watch out for any further deviations from nominal performance. We have suspected several minor irregularities in the past few days, but none have been important enough for remedial action, and they have shown no obvious pattern from which we can draw any conclusions. We are running further tests with both our computers and will report as soon as the results are available. We repeat that there is no need for alarm; the worst that can happen is that we may have to disconnect your nine-triple-zero temporarily for program analysis, and hand over control to one of our computers. The time lag will introduce problems, but our feasibility studies indicate that Earth control is perfectly satisfactory at this stage of the mission.
“X-ray-Delta-One, this is Mission Control, two-one-five-six, transmission concluded.”
Frank Poole, who was on watch when the message came in, thought this over in silence. He waited to see if there was any comment from Hal, but the computer did not attempt to challenge the implied accusation. Well, if Hal would not raise the subject, he did not propose to do so either.
It was almost time for the morning changeover, and normally he would wait until Bowman joined him on the control deck. But today he broke this routine, and made his way back to the carrousel.
Bowman was already up, pouring himself some coffee from the dispenser, when Poole greeted him with a rather worried “good morning.” After all these months in space, they still thought in terms of the normal twenty-four-hour cycle – though they had long since forgotten the days of the week.
“Good morning,” replied Bowman. “How’s it going?” Poole helped himself to coffee. “Pretty well. Are you reasonably awake?”
“I’m fine. What’s up?”
By this time, each knew at once when anything was amiss. The slightest interruption of the normal routine was a sign that had to be watched.
“Well,” Poole answered slowly. “Mission Control has just dropped a small bomb on us.” He lowered his voice, like a doctor discussing an illness in front of the patient. “We may have a slight case of hypochondria aboard.”
Perhaps Bowman was not fully awake, after all; it took him several seconds to get the point. Then he said “Oh-I see. What else did they tell you?”
“That there was no cause for alarm. They said that twice, which rather spoiled the effect as far as I was concerned. And that they were considering a temporary switchover to Earth control while they ran a program analysis.”
They both knew, of course, that Hal was hearing every word, but they could not help these polite circumlocutions. Hal was their colleague, and they did not wish to embarrass him. Yet at this stage it did not seem necessary to discuss the matter in private.
Bowman finished his breakfast in silence, while Poole toyed with the empty coffee container. They were both thinking furiously, but there was nothing more to say.
They could only wait for the next report from Mission Control – and wonder if Hal would bring up the subject himself. Whatever happened, the atmosphere aboard the ship had subtly altered. There was a sense of strain in the air – a feeling that, for the first time, something might be going wrong.
Discovery was no longer a happy ship.
24 – Broken Circuit
Nowadays, one could always tell when Hal was about to make an unscheduled announcement. Routine, automatic reports, or replies to questions that had been put to him, had no preliminaries; but when he was initiating his own outputs there would be a brief electronic throat-clearing. It was an idiosyncrasy that he had acquired during the last few weeks; later, if it became annoying, they might do something about it. But it was really quite useful, since it alerted his audience to stand by for something unexpected.
Poole was asleep, and Bowman was reading on the control deck, when Hal announced:
“Er – Dave, I have a report for you.”
“What’s up?”
“We have another bad AE-35 unit. My fault predictor indicates failure within twenty-four hours.”
Bowman put down his book and stared thoughtfully at the computer console. He knew, of course, that Hal was not really there, whatever that meant. If the computer’s personality could be said to have any location in space, it was back in the sealed room that contained the labyrinth of interconnected memory units and processing grids, near the central axis of the carrousel. But there was a kind of psychological compulsion always to look toward the main console lens when one addressed Hal on the control deck, as if one were speaking to him face to face. Any other attitude smacked of discourtesy.
“I don’t understand it, Hal. Two units can’t blow in a couple of days.”
“It does seem strange, Dave. But I assure you there is an impending failure.”
“Let me see the tracking alignment display.”
He knew perfectly well that this would prove nothing, but he wanted time to think. The expected report from Mission Control had still not arrived; this might be the moment to do a little tactful probing.
There was the familiar view of Earth, now waxing past the half-moon phase as it swept toward the far side of the Sun and began to turn its full daylight face toward them. It was perfectly centered on the crosswires; the thin pencil of the beam still linked Discovery to her world of origin. As, of course, Bowman knew it must do. If there had been any break in communication, the alarm would already have sounded.
“Have you any idea,” he said, “what’s causing the fault?”
It was unusual for Hal to pause so long. Then he answered:
“Not really, Dave. As I reported earlier, I can’t localize the trouble.”
“You’re quite certain,” said Bowman cautiously, “that you haven’t made a mistake? You know that we tested the other AB-35 unit thoroughly, and there was nothing wrong with it.”
“Yes, I know that. But I can assure you that there is a fault. If it’s not in the unit, it may be in the entire subsystem.”
Bowman drummed his fingers on the console. Yes, that was possible, though it might be very difficult to prove – until a breakdown actually occurred and pinpointed the trouble.
“Well, I’ll report it to Mission Control and we’ll see what they advise.” He paused, but there was no reaction.
“Hal,” he continued, “is something bothering you – something that might account for this problem?”
Again there was that unusual delay. Then Hal answered, in his normal tone of voice:
“Look, Dave, I know you’re trying to be helpful. But the fault is either in the antenna system – or in your test procedures. My information processing is perfectly normal. If you check my record, you’ll find it completely free from error.”
“I know all about your service record, Hal – but that doesn’t prove you’re right this time. Anyone can make mistakes.”
“I don’t want to insist on it, Dave, but I am incapable of making an error.”
There was no safe answer to that; Bowman gave up the argument.
“All right, Hal,” he said, rather hastily. “I understand your point of view. We’ll leave it at that.”
He felt like adding “and please forget the whole matter.” But that, of course, was the one thing that Hal could never do.
It was unusual for Mission Control to waste radio bandwidth on vision, when a speech circuit with teletype confirmation was all that was really necessary. And the face that appeared on the screen was not that of the usual controller; it was the Chief Programmer, Dr. Simonson. Poole and Bowman knew at once that this could only mean trouble.