"This is a spoken sentence." "Negative"
"This is a coded signal." "Affirmative."
"Pour me a drink," Jason said with the microphone off. "This playing twenty questions may take some time." It did. But patient working around the subject supplied, bit by bit, the needed information. Jason turned off the radio and passed over the scribbled sheet. "This is something at least. The code signal is a ten-digit number.
If we send the correct number, all the mothballing activity stops instantly and the ship is under our control."
"And the money is ours," Meta said. "Can our computer be programmed to send a series of numbers until it hits on the right one?"
"It can—and just the same thought crossed my mind. The Indestructible thinks that we are running a communications check and tells me that it can accept up to seven hundred signals a second for repeat and verification. Our computer will read the returned signal and send an affirmative answer to each one. But of course all the signals will be going through the discrimination circuits, and if the correct signal is sent, the mothball defenses will be turned off."
"That seems like an obvious trick that would not fool a five-year-old," Kerk said.
"Never underestimate the stupidity of a computer. You forget that it is a machine with zero imagination. Now, let me see if this will do us any good." He punched keys rapidly, then muttered a curse and kicked the console. "No good. We will have to run nine to the tenth power numbers and, at seven hundred a second, it will take us about five months to do them all." . "And we have just three weeks left."
"I can still read a calendar, thank you, Meta. But we'll have to try in any case. Send alternate numbers from one up and counting from 9,999,999,999 back down. Then we'll get the navy code department to give us all their signals to send as well; one of them might fit. The odds are still about five to one against hitting the right combination, but that is better than no odds at all. And we'll keep working to see what else we can think of."
The navy sent over a small man named Shrenkly who brought a large case of records. He was head of the code department, and a cipher and puzzle enthusiast as well. This was the greatest challenge of his long and undistinguished career, and he hurled himself into it. "Wonderful opportunity, wonderful. The ascending and descending series are going out steadily. In the meantime I am taping permutations and substitutions of signals which will—"
"That's fine, keep at it," Jason said, smiling enthusiastically and patting the man on the back. "I'll get a report from you later, but right now we have a meeting to attend. Kerk, Meta, time to go."
"What meeting?" Meta asked as he tried to get her through the door.
"The meeting I just made up to get away from that bore," he said when he finally got her into the corridor. "Let him do his job while we see if we can find another way in."
"I think what he has to say is very interesting."
"Fine. You talk to him—but not while I am around. Let us now spur our brains into action and see what we can come up with."
What they came up with was a number of ideas of varying quality and uniform record of failure. There was the miniature flying robot fiasco where smaller and smaller robots were sent and blasted out of existence, right down to the smallest, about the size of a small coin. Obsessed by miniaturization, they constructed a flying-eye apparatus no larger than the head of a pin that dragged a threadlike control wire after it that also supplied current for the infinitesimal ion drive. This sparked and sizzled its way to within fifteen kilometers of the Indestructible before the all-seeing sensors detected it and neatly blasted it out of existence with a single shot. There were other suggestions and brilliant plans, but none of them worked out in practice. The great ship floated serenely in space reading seven hundred numbers a second and, in its spare time, blowing into fine dust any object that came near it. Each attempt took time, and the days drifted by steadily. Jason was beginning to have a chronic headache and had difficulty sleeping. The problem seemed insoluble. He was feeding figures about destruction distances into the computer when Meta looked in on him. "I'll be with Shrenkly if you need me," she said. "Wonderful news."
"He taught me about frequency tables yesterday, and today he is going to start me on simple substitution ciphers."
"How thrilling."
"Well, it is—to me. I've never done anything like this before. And it has some value: we are sending signals and one of them could be the correct one. It certainly is accomplishing more than you are with all your flying rocks. With two days to go, too."
She stalked out and slammed the door, and Jason slumped with fatigue, aware that failure was hovering close. He was pouring himself a large glass of Old Fatigue Killer when Kerk came in. "Two days to go," Kerk said.
"Thanks. I didn't know until you told me. I know that a Pyrran never gives up, but I am getting the sneaking suspicion that we are licked."
"We are not beaten yet. We can fight."
"A very Pyrran answer—but it won't work this time. We just can't barge in there in battle armor and shoot the place up."
"Why not? Small-arms fire would just bounce off us as well as the low-power rays. All we have to do is dodge the big stuff and bull through."
"That's all! Do you have any idea how we are going to arrange that?"
"No. But you will figure something out. But you better hurry."
"I know, two days. I suppose it's easier to die than admit failure. We suit up, fly at the battleship behind a fleet of rocks that are blasted by the heavy stuff. Then we tell the enemy discrimination circuits that we are not armored spacesuits at all, but just a couple of jettisoned plastic beer barrels that they can shoot up with the small-caliber stuff. Which then bounces off us like hail and we land and get inside and get a billion credits and live happily ever after."
"That's the sort of thing. I'll go get the suits ready."
"Before you do that, just consider one thing in this preposterous plan. How do we tell the discrimination circuitry…" Jason's voice ran down in midsentence, and his eyes opened wide—then he clapped Kerk on the back. Heavily too, he was so excited, but the Pyrran seemed completely unaware of the blow. "That's it, that's how we do it!" Jason chortled, rushing to the computer console. Kerk waited patiently while Jason fed in figures and muttered over the tapes of information. The answer was not long in coming.
"Here it is!" Jason held up a reel of tape. "The plan of attack—and it is going to work. It is just a matter of remembering that the computer on that battleship is just a big dumb adding machine that counts on its fingers, but very fast. It always performs in the same manner because it is programmed to do so. So here is what happens. Because of the main drive tubes the area with the least concentration of fire power is dead astern. Only one hundred and fourteen gun turrets can be trained that way. Their slew time varies—that is, the time it takes a turret to rotate one hundred and eighty degrees in azimuth. The small ones do it in less than a second; the main batteries need six seconds. This is one factor. Other factors are which targets get that kind of attention. Fastest-moving rocks get blasted first, even if they are farther away than a larger, slower-moving target. There are other factors like rate of fire, angle of depression of guns and so forth. Our computer has chomped everything up and come up with this!"
"What does it reveal?"
"That we can make it. We will be in the center of a disk of flying rocks that will be aimed at the rear of the Indestructible. There will be a lot of rocks, enough to keep all the guns busy that can bear on the spot. Our suits will be half the size of the smallest boulder. We will all be going at the same speed, in the same direction, so we should get the small-caliber stuff. Now, another cloud of rocks, real heavy stuff, will converge on the stern of the ship from a ninety-degree angle, but it will not hit the two-hundred-kilometer limit until after the guns start blasting at us. The computer will track it and as soon as our wave is blasted will slew the big guns to get rid of the heavy stuff. As soon as these fire, we accelerate toward the stern tubes. We will then become prime targets, but, before the big guns can slew back, we should be inside the tubes."