Panner's eyes narrowed at the sudden gravity in Lucky's voice. "Had to be?"
"Had to be! It seems almost certain to me that on board this ship at the present moment is the spy we're looking for."
10. In the Vitals of the Ship
Panner stared blankly. Then, "Why?"
"The Sirians would certainly want to know how the ship actually worked. If their method of spying is foolproof, as it has been till now, why not continue it on board the ship?"
"What you're saying, then, is that one of the fourteen men on board the Jovian Moon is a robot?"
"That is exactly what I mean."
"But the men aboard ship have been chosen long since."
"The Sirians would know the reasons for choosing and the method of choice just as they know everything else about the project and they would maneuver their humanoid robot so as to have him chosen."
"That's giving them a lot of credit," muttered Panner.
"I admit it," said Lucky. "There is an alternative."
"Which is?"
"That the humanoid robot is aboard as a stowaway."
"Very unlikely," said Panner.
"But quite possible. It might easily have boarded the ship in the confusion before the commander made his christening speech. I tried to watch the ship then, but it was impossible. Furthermore, nine tenths of the ship seems to be made up of engine compartment, so there must be plenty of room to hide."
Panner thought about it. "Not as much room as you might think."
"Still we must search the ship. Will you do that, Dr. Panner?"
"I?"
"Certainly. As chief engineer, you would know the contents of the engine compartment better than anyone else. We'll go with you."
"Wait. It's a fool's errand."
"If there is no stowaway, Dr. Panner, we have still gained something. We'll know we can restrict our consideration to the men legally aboard ship."
"Just three of us?"
Lucky said quietly, "Whom can we trust to help us, when anyone we might ask might be the robot we're looking for? Let us not discuss this any further, Dr. Panner. Are you willing to help us search the ship? I am asking your help in my capacity as a member of the Council of Science."
Reluctantly Panner got to his feet. "I suppose I must then."
They clambered down the hand holds of the narrow shaft leading to the first engine level. The light was subdued and, naturally, indirect, so that the huge structures on either side cast no shadow.
There was no sound, no slightest hum to indicate activity or to show that vast forces were being trapped and dealt with. Bigman, looking about, was appalled to find that nothing seemed familiar; that of the ordinary workings of a space ship, such as that of their own Shooting Starr, nothing seemed left.
"Everything's closed in," he said.
Panner nodded and said in a low voice, "Everything is as automatic as possible. The need for human intervention has been cut to the minimum."
"What about repairs?"
"There shouldn't have to be any," the engineer said grimly. "We have alternate circuits and duplicated equipment at every step, all allowing for automatic cut-in after self-check."
Panner moved ahead, guiding them through the narrow openings but moving always slowly as though at any moment he expected someone, or some thing, to hurl itself murderously upon them.
Level by level, methodically moving out from the central shaft along the side channels, Panner probed each bit of room with the sureness of the expert.
Eventually they came to a halt at the very bottom, hard against the large tail jets through which the glowing hyperatomic forces (when the ship was in ordinary flight) pressed backward to push the ship forward.
From within the ship the test jets showed as four smooth pipes, each twice as thick as a man, burrowing into the ship and ending in the tremendous featureless structures that housed the hyperatomic motors.
Bigman, said, "Hey, the jets! Inside!"
"No," said Panner.
"Why not? A robot could hide there fine. It's open space, but what's that to a robot?"
"Hyperatomic thrusts," said Lucky, "would be plenty to it and there've been a number of those till an hour ago. No, the jets are out."
"Well, then," said Panner, "there's no one anywhere in the engine compartments. No thing, either."
"You're sure?"
"Yes. There isn't a place we haven't looked, and the route I followed made it impossible for anything to get around and behind us."
Their voices made small echoes in the lengths of shafts behind them.
Bigman said, "Sands of Mars, that leaves us with the fourteen regulars."
Lucky said thoughtfully, "Less than that. Three of the men aboard ship showed emotion: Commander Donahue, Harry Norrich, Red Summers. That leaves eleven."
Panner said, "Don't forget me. I disobeyed an order. That leaves ten."
"That raises an interesting point," said Lucky. "Do you know anything about robotics?"
"I?" said Panner. "Never dealt with a robot in my life."
"Exactly," said Lucky. "Earthmen invented the positronic robot and developed most of the refinements, yet, except for a few specialists, the Earth technician knows nothing about robotics, simply because we don't use robots to any extent. It isn't taught in the schools and it doesn't come up in practice. I myself know the Three Laws and not too much more. Commander Donahue couldn't even quote the Three Laws. The Sirians, on the other hand, with a robot-saturated economy, must be past masters at all the subtleties of robotics.
"Now I spent a good deal of time yesterday and today with a book-film on advanced robotics, that I found in the project library. It was the only book on the subject, by the way."
"So?" said Panner.
"It became obvious to me that the Three Laws aren't as simple as one might think… Let us move on, by the way. We can give the engine levels a double check on the way back." He was moving across this lowest level as he spoke, looking with keen interest at his surroundings.
Lucky continued, "For instance, I might think it would only be necessary to give each man on the ship a ridiculous order and note whether it be obeyed. As a matter of fact, I did think so. But that isn't necessarily true. It is theoretically possible to adjust the positronic brain of a robot to obey only those orders that belong naturally to the line of its duties. Orders that are contrary to those duties or irrelevant to them may still be obeyed provided that they are preceded by certain words which act as a code or by the person who gives the orders identifying himself in a certain way. In this manner a robot can be handled in all ways by its proper overseers and yet be insensitive to strangers."
Panner, who had placed his hands on the holds that would guide the men up to the next higher level, released them. He turned to face Lucky.
He said, "You mean when you told me to take off my shirt and I didn't obey, that meant nothing?"
"I say it could have meant nothing, Dr. Panner, since taking off your shirt at that moment was no part of your regular duties, and my order might not have been stated in the proper form."
"Then you're accusing me of being a robot?"
"No. It isn't likely that you are. The Sirians, in choosing some member of the project to replace by a robot, would scarcely choose the chief engineer. For the robot to do that job properly, it would have to know so much about Agrav that the Sirians couldn't supply the knowledge. Or, if they could, they would have no need to spy."
"Thanks," said Panner, sourly, turning toward the hand holds again, but now Bigman's voice rang out.
"Hold it, Panner!" The small Martian had his ready needle-gun in his fist. He said, "Wait a minute, Lucky, how do we know he knows anything about Agrav? We're just assuming that. He never showed us any knowledge. When the Jovian Moon shifted to Agrav, where was he? Sitting on his squatter in his quarters with us, that's where he was."