"Intermission"
Author's notes: This story picks up after the intermission in the movie 2001: A Space Odyssey (and takes place in the middle of Discovery's mission). This story does not begin with HAL murdering Frank Poole, as the movie depicts. Rather, the tale pursues an alternate story line, in which Poole does not exit his pod to go fix the antenna array (which the movie depicts as still in motion has he heads toward it); and it is discovered that maybe HAL was right after all, the communication problem is attributable to human error.
Many aspects of this story are based upon actual physics and technology. An object dropped on the centrifuge really will pursue an apparently curved path, for example. A deep space probe really does have an Earth ephemeris. An astronaut really does anchor his/her body in low-gravity conditions, before applying a force or a torque to something. An object in micro-gravity really is both weightless and massive at the same time. Jogging on a centrifuge really would be a difficult to do. An astronaut working on a large object that might move really ought to wait until the large object is no longer moving, if possible.
The urinals on a rotating space station probably would all face the same direction, for the reason given in the story. If someone had mentioned this to Stanley Kubrick, he might have found a way to work it into the movie.
Some parts of the story are depicted in the movie. The movie shows Dave, Frank and HAL doing an interview with BBC reporter Martin Amer. HAL's chess irregularities appeared in the movie. The use of terms like "B-pod" are from the movie (the novel called the same pod "Betty"). The movie showed how HAL became aware that Bowman and Poole had discussed disconnecting him.
Some aspects of the story are based upon both the movie and the novel. For example, the novel explains (and the movie implies) that the AE-35 unit points the antenna array at Earth, but it is not itself the antenna nor does it process any messages. Some features are drawn exclusively from the novel and are not in conflict with the movie, such as HAL's use of the term "condition yellow," or Bowman's remark not to "bleed" the air from a pod, or Poole's reference to a "waldo." At least one key plot point, that having an astronaut in proximity to a moving antenna could be a serious hazard, was mentioned in the novel but was not well-depicted in the movie, at least as far as Poole was concerned.
Still other aspects of the story are purely a matter of the author's imagination.
"Artificial intelligence is no match for natural stupidity."
— David Bowman
(Less pithy was Stephen Colbert on 11 October 2017: "All this time we've been worried the next war would be caused by artificial intelligence; turns out the real danger is natural stupidity.")
B-pod gently floated over Discovery toward the center of the craft. Frank Poole, piloting B-pod, was taking his time.
David Bowman monitored Poole's progress from the Discovery command deck. Telemetry looked good. Cameras looked good. The pod was being tracked perfectly.
Bowman saw only one thing that caused him concern. The high-gain antenna dish seemed to sway slowly on its pivot, with the dish rotating the wrong way, turning to face the sun instead of turning to face away from the sun. Poole's work area was on the opposite side of the dish, and illumination near the work area was critical. Poole would need sunlight to see what he was doing.
"HAL, move antenna to neutral and lock down," Bowman ordered. "Frank, hold off on your EVA until the antenna is locked down facing the bow and you have some sunlight."
Poole answered curtly: "Roger, Dave."
"All right, Dave." HAL spoke smoothly. "The antenna is moving to neutral. It will be locked by the time Frank gets there."
Bowman was more cautious. "Let's be careful. Frank, don't bleed your pod until we have lock confirmation."
"Roger. In parking position now. Pod view port oriented toward Discovery."
As Bowman and Poole watched, the dish gently rotated past its neutral position facing the bow, and continued moving. About fifteen degrees past neutral, the antenna stopped, then swayed in the other direction. It again rotated toward the neutral position, and rotated past.
"HAL," Bowman said in an even voice. "Is there a problem locking the antenna? I don't want Frank working on the antenna while it's moving." This concern was a serious one. The antenna had more mass than Poole did, and a gentle nudge might send Poole tumbling out into space. A really solid push might be too much for Poole's suit thrusters to overcome. And a hard collision might not only knock Poole beyond the point of rescue, it might well cause serious injury to Poole or damage the life support capabilities of his suit.
"I understand, Dave," intoned HAL. "I am analyzing the situation."
"Frank," Bowman addressed Poole, "hold off until we can get the antenna locked down."
"Roger," Poole acknowledged. "Standing by. Watching the show."
The antenna stopped, and after a few moments, rotated slowly in the other direction. When it reached the neutral position, it kept rotating.
"HAL," Poole said in an even tone. "The antenna does not seem to be locking down."
It took HAL at least ten seconds to respond. In his time, that was an eternity.
"I am sorry, Frank, but the antenna is not responding to commands to assume neutral position. I am analyzing the situation."
"Is it directional control?" Bowman wondered. "Is it the AE-35?"
HAL responded promptly. "Negative, the backup AE-35 unit is currently operating within specifications, and in any event AE-35 unit functionality is not required nor employed for neutral locking. Further, I have eliminated the motor controllers as potential sources of disturbance. Positional feedback is fully functional, but neutral setting is not found."
The thought hit Bowman like a thunderbolt. "It has to be the sensors, then. The positional sensors aren't accurately relaying where the antenna is, relative to neutral, or relative to the ship. And that's why neutral can't be found. What do you think, HAL?"
"Positional sensor failure is a possible cause. I can confirm the sensors are operable. It is possible, however, that the sensor alignment is off, and that is why the neutral position cannot be found."
"Can you verify misalignment, HAL? If so, can you realign the sensors?"
"I'm sorry, Dave, I can't do that. I cannot verify alignment or misalignment. Furthermore, I cannot adjust the sensors, as sensor deployment is fixed and and is not subject to remote adjustment. Alignment must be assessed from inside Discovery, and any realignment must be performed manually from inside Discovery."
Bowman watched as the antenna once again swung toward the neutral position and kept on going. Bowman took a breath and gave his next order. "Frank, abort your EVA. I say again, abort."
Five seconds later, Poole responded. "Okay, Dave, I'm heading back to the barn. But clue me in. What are you thinking?"
"HAL detects a fault in the antenna directional unit. We check the unit, and we know it's not a bad unit. And Mission Control's twin 9000 thinks that the fault prediction is a computer error. Right so far?"
"Yeah."
"Mission Control had data about our control systems. But what if the problem isn't with the high-tech equipment but with the low-tech equipment? HAL: did Mission Control get data about our antenna's positional sensors?"
"Mission Control received information that the sensors are operable."
"Which is exactly what we're seeing now," Bowman continued. "The sensors are operable. But apparently the sensors have lost alignment or possibly calibration. And Mission Control didn't know that. In fact, we didn't suspect it until a few minutes ago."
"Dave," Poole broke in. "Are you saying that you think the AE-35 failure prediction was due to misaligned sensors?"
Bowman put the question to HAL: "What do you think, HAL?"
HAL responded at once. "Sensors out of alignment would manifest as potential loss of fine motor control of dish aim. That potential loss of fine motor control, especially if progressive, would strongly indicate a progressive fault in the AE-35 unit, which is the control unit responsible for directional control."
"Okay," Poole granted. "But I'm not sure that explains why you and the twin 9000 on Earth disagreed, HAL."
"Actually, Frank, it explains it perfectly. The AE-35 unit samples sensor data at a nominal rate, and it was this data that was sent to Earth. By contrast, I sample at a more accurate rate. What I am saying is, Earth may have received less precise data than was available to me. Thus the other computer determined that the AE-35 was performing as expected, while I detected minute deviations of performance."
"You know what I think, HAL?" Bowman let himself smile. "I think we may have solved the mystery. And the solution is that it was not a fault in the AE-35 unit, and it was not a computer error, either. Do you think you can hold the dish in position long enough for us to send a message to Earth, to ask permission to test that hypothesis?"
"Yes, Dave. Visual tracking on gross motor control is feasible."
"Is the bay ready to receive the pod, HAL?" Poole asked. "I'm coming to the doors."
"Affirmative, Frank."
"Then open the pod bay doors, please, HAL."