The Space Trilogy (29 page)

“Couldn’t you spit your way towards it?” said Gibson solemnly. “I thought that was the approved way out of the difficulty.”

“You try it someday and see how far it gets you. Anyway, it’s not hygienic. Do you know what I had to do? It was most embarrassing. I was only wearing shorts and vest, as usual, and I calculated that they had about a hundredth of my mass. If I could throw them away at thirty meters a second, I could reach the wall in about a minute.”

“And did you?”

“Yes. But the Director was showing his wife round the Station that afternoon, so now you know why I’m reduced to earning my living on an old hulk like this, working my way from port to port when I’m not running a shady surgery down by the docks.”

“I think you’ve missed your vocation,” said Gibson admiringly. “You should be in my line of business.”

“I don’t think you believe me,” complained Scott bitterly.

“That’s putting it mildly. Let’s look at your toy.”

Scott handed it over. It was a modified air pistol, with a spring-loaded reel of nylon thread attached to the butt.

“It looks like—”

“If you say it’s like a ray-gun I’ll certify you as infectious. Three people have made that crack already.”

“Then it’s a good job you interrupted me,” said Gibson, handing the weapon back to the proud inventor. “By the way, how’s Owen getting on? Has he contacted that missile yet?”

“No, and it doesn’t look as if he’s going to. Mac says it will pass about a hundred and forty-five thousand kilometres away—certainly out of range. It’s a damn shame; there’s not another ship going to Mars for months, which is why they were so anxious to catch us.”

“Owen’s a queer bird, isn’t he?” said Gibson with some inconsequence.

“Oh, he’s not so bad when you get to know him. It’s quite untrue what they say about him poisoning his wife. She drank herself to death of her own free will,” replied Scott with relish.

Owen Bradley, PhD., MIEE, MIRE, was very annoyed with life. Like every man aboard the
Ares,
he took his job with a passionate seriousness, however much he might pretend to joke about it. For the last twelve hours he had scarcely left the communications cabin, hoping that the continuous carrier wave from the missile would break into the modulation that would tell him it was receiving his signals and would begin to steer itself towards the
Ares.
But it was completely indifferent, and he had no right to expect otherwise. The little auxiliary beacon which was intended to call such projectiles had a reliable range of only twenty thousand kilometres; though that was ample for all normal purposes, it was quite inadequate now.

Bradley dialled the astrogation office on the ship’s intercom, and Mackay answered almost at once.

“What’s the latest, Mac?”

“It won’t come much closer. I’ve just reduced the last bearing and smoothed out the errors. It’s now a hundred and fifty thousand kilometres away, travelling on an almost parallel course. Nearest point will be a hundred and forty-four thousand, in about three hours. So I’ve lost the sweep—and I suppose we lose the missile.”

“Looks like it, I’m afraid,” grunted Bradley, “but we’ll see. I’m going down to the workshop.”

“Whatever for?”

“To make a one-man rocket and go after the blasted thing, of course. That wouldn’t take more than half an hour in one of Martin’s stories. Come down and help me.”

Mackay was nearer the ship’s equator than Bradley; consequently he had reached the workshop at the South Pole first and was waiting in mild perplexity when Bradley arrived, festooned with lengths of coaxial cable he had collected from stores. He outlined his plan briefly.

“I should have done this before, but it will make rather a mess and I’m one of those people who always go on hoping till the last moment. The trouble with our beacon is that it radiates in all directions—it has to, of course, since we never know where a carrier’s coming from. I’m going to build a beam array and squirt
all
the power I’ve got after our runaway.”

He produced a rough sketch of a simple Yagi aerial and explained it swiftly to Mackay.

“This dipole’s the actual radiator—the others are directors and reflectors. Antique, but it’s easy to make and it should do the job. Call Hilton if you want any help. How long will it take?”

Mackay, who for a man of his tastes and interests had a positively atavistic skill with his hands, glanced at the drawings and the little pile of materials Bradley had gathered.

“About an hour,” he said, already at work. “Where are you going now?”

“I’ve got to go out on the hull and disconnect the plumbing from the beacon transmitter. Bring the array round to the airlock when you’re ready, will you?”

Mackay knew little about radio, but he understood clearly enough what Bradley was trying to do. At the moment the tiny beacon on the
Ares
was broadcasting its power over the entire sphere of space. Bradley was about to disconnect it from its present aerial system and aim its whole output accurately towards the fleeing projectile, thus increasing its range many-fold.

It was about an hour later that Gibson met Mackay hurrying through the ship behind a flimsy structure of parallel wires, spaced apart by plastic rods. He gaped at it in amazement as he followed Mackay to the lock, where Bradley was already waiting impatiently in his cumbersome spacesuit, the helmet open beside him.

“What’s the nearest star to the missile?” Bradley asked. Mackay thought rapidly.

“It’s nowhere near the ecliptic now,” he mused. “The last figures I got were—let’s see—declination fifteen something north, right ascension about fourteen hours. I suppose that will be—I never can remember these things!—somewhere in Böotes. Oh yes—it won’t be far from Arcturus: not more than ten degrees anyway, I’d say at a guess. I’ll work out the exact figures in a minute.”

“That’s good enough to start with. I’ll swing the beam around, anyway. Who’s in the Signals Cabin now?”

“The Skipper and Fred. I’ve rung them up and they’re listening to the monitor. I’ll keep in touch with you through the hull transmitter.”

Bradley snapped the helmet shut and disappeared through the airlock. Gibson watched him go with some envy. He had always wanted to wear a spacesuit, but though he had raised the matter on several occasions Norden had told him it was strictly against the rules. Spacesuits were very complex mechanisms and he might make a mistake in one—and then there would be hell to pay and perhaps a funeral to be arranged under rather novel circumstances.

Bradley wasted no time admiring the stars once he had launched himself through the outer door. He jetted slowly over the gleaming expanse of hull with his reaction units until he came to the section of plating he had already removed. Underneath it a network of cables and wires lay nakedly exposed to the blinding sunlight, and one of the cables had already been cut. He made a quick temporary connection, shaking his head sadly at the horrible mismatch that would certainly reflect half the power right back to the transmitter. Then he found Arcturus and aimed the beam towards it. After waving it around hopefully for a while, he switched on his suit radio.

“Any luck?” he asked anxiously.

Mackay’s despondent voice came through the loudspeaker.

“Nothing at all. I’ll switch you through to communications.”

Norden confirmed the news.

“The signal’s still coming in, but it hasn’t acknowledged us yet.”

Bradley was taken aback. He had been quite sure that this would do the trick; at the very least, he must have increased the beacon’s range by a factor of ten in this one direction. He waved the beam around for a few more minutes, then gave it up. Already he could visualize the little missile with its strange but precious cargo slipping silently out of his grasp, out towards the unknown limits of the Solar System—and beyond.

He called Mackay again.

“Listen, Mac,” he said urgently, “I want you to check those co-ordinates again and then come out here and have a shot yourself. I’m going in to doctor the transmitter.”

When Mackay had relieved him, Bradley hurried back to his cabin. He found Gibson and the rest of the crew gathered glumly round the monitor receiver from which the unbroken whistle from the distant, and now receding, missile was coming with a maddening indifference.

There were very few traces of his normally languid, almost feline movements as Bradley pulled out circuit diagrams by the dozen and tore into the communications rack. It took him only a moment to run a pair of wires into the heart of the beacon transmitter. As he worked, he fired a series of questions at Hilton.

“You know something about these carrier missiles. How long must it receive our signal to give it time to home accurately on to us?”

“That depends, of course, on its relative speed and several other factors. In this case, since it’s a low-acceleration job, a good ten minutes, I should say.”

“And then it doesn’t matter even if our beacon fails?”

“No. As soon as the carrier’s vectored itself towards you, you can go off the air again. Of course, you’ll have to send it another signal when it passes right by you, but that should be easy.”

“How long will it take to get here if I
do
catch it?”

“A couple of days, maybe less. What are you trying out now?”

“The power amplifiers of this transmitter run at seven hundred and fifty volts. I’m taking a thousand-volt line from another supply, that’s all. It will be a short life and a merry one, but we’ll double or treble the output while the tubes last.”

He switched on the intercom and called Mackay, who, not knowing the transmitter had been switched off for some time, was still carefully holding the array lined up on Arcturus, like an armour-plated William Tell aiming a crossbow.

“Hello, Mac, you all set?”

“I am practically ossified,” said Mackay with dignity. “How much longer—”

“We’re just starting now. Here goes.”

Bradley threw the switch. Gibson, who had been expecting sparks to start flying, was disappointed. Everything seemed exactly as before; but Bradley, who knew better, looked at his meters and bit his lips savagely.

It would take radio waves only half a second to bridge the gap to that tiny, far-off rocket with its wonderful automatic mechanisms that must remain forever lifeless unless this signal could reach them. The half-second passed, and the next. There had been time for the reply, but still that maddening heterodyne whistle came unbroken from the speaker. Then, suddenly, it stopped. For an age there was absolute silence. A hundred and fifty thousand kilometres away, the robot was investigating this new phenomenon. It took perhaps five seconds to make up its mind—and the carrier wave broke through again, but now modulated into an endless string of “beep-beep-beeps.”

Bradley checked the enthusiasm in the cabin.

“We’re not out of the wood yet,” he said. “Remember it’s got to hold our signal for ten minutes before it can complete its course alterations.” He looked anxiously at his meters and wondered how long it would be before the output tubes gave up the unequal battle.

They lasted seven minutes, but Bradley had spares ready and was on the air again in twenty seconds. The replacements were still operating when the missile carrier wave changed its modulation once more, and with a sigh of relief Bradley shut down the maltreated beacon.

“You can come indoors now, Mac,” he called into the microphone. “We made it.”

“Thank heavens for that. I’ve nearly got sunstroke, as well as calcification of the joints, doing this Cupid’s bow act out here.”

“When you’re finished celebrating,” complained Gibson, who had been an interested but baffled spectator, “perhaps you’ll tell me in a few short, well-chosen phrases just how you managed to pull this particular rabbit out of the hat.”

“By beaming our beacon signal and then overloading the transmitter, of course.”

“Yes, I know that. What I don’t understand is why you’ve switched it off again.”

“The controlling gear in the missile has done its job,” explained Bradley, with the air of a professor of philosophy talking to a mentally retarded child. “That first signal indicated that it had detected our wave; we knew then that it was automatically vectoring on to us. That took it several minutes, and when it had finished it shut off its motors and sent us the second signal. It’s still at almost the same distance, of course, but it’s heading towards us now and should be passing in a couple of days. I’ll have the beacon running again then. That will bring it to within a kilometre or less.”

"Hey!" said Gibson in sudden alarm. "Suppose it scores a direct hit on us?"

"You might give its designers credit for having thought of that. When it gets very close a neat little device sensitive to the gradient of the beacon's field comes into play. Since, as you are well aware, the field strenght
H
is inversely proportional to the distance
r
, then it is immediately obvious tha
dH/dr
varies inversely as
r
squared, and so is too small to be measured unless tou're very close. When the missile finds it
can
measure it, it puts on the brakes."