by Hal Clement
The calcium chloride cells were easy to locate; Ridging removed two of the half-dozen to be on the safe side, replaced and reassembled the renewer, tightened the connections, and reopened the valves.
Ridging now had two cans of calcium chloride. He could not tell whether it had yet absorbed enough water actually to go into solution, though he doubted it; but he took no chances. Holding one of the little containers carefully right side up, he opened its perforated top, took a specimen bag and pushed it into the contents. The plastic was not, of course, absorptive — it was not the first time in the past hour he had regretted the change from cloth bags — but the damp crystals should adhere, and the solution if there was any would wet it. He pulled out the material and applied it to his faceplate.
It was not until much later that he became sure whether there was any liquid. For the moment it worked, and he found that he could see; he asked no more. Hastily he repeated the process on Shandara's helmet, and the two set out rapidly for the rim. They did not stop to pick up camera or map.
Travel is fast on the Moon, but they made less than four hundred meters. Then the faceplates were covered again. With a feeling of annoyance they stopped, and Ridging repeated the treatment.
This time it didn't work.
“I supposed you emptied the can while you were jumping,” Shandara remarked in an annoyed tone. “Try the other one.”
“I didn't empty anything; but I'll try.” The contents of the other container proved equally useless, and the cartographer's morale took another slump.
“What happened?” he asked. “And please don't tell me it's obvious, because you certainly didn't foresee it.”
“I didn't, but it is. The chloride dried out again.”
“I thought it held onto water.”
“It does, under certain conditions. Unfortunately its equilibrium vapor pressure at this temperature is higher than the local barometer reading. I don't suppose that every last molecule of water has gone, but what's left isn't sufficient to make a conductor. Our faceplates are holding charge again — maybe better than before; there must be some calcium chloride dust on them now, though I don't know offhand what effect it would have.”
“There are more chloride cartridges in the cyclers.”
“You have four left, which would get us maybe two kilos at the present rate. We can't use mine, since you can't get them out; and if we use all yours you'd never get up the rim. Drying your air isn't just a matter of comfort, you know; that suit has no temperature controls — it depends on radiation balance and insulation. If your perspiration stops evaporating, your inner insulation is done; and in any case, the cartridges won't get us to the rim.”
“In other words you think we're done — again.”
“I certainly don't have any more ideas.”
“Then I suppose I'll have to do some more pointless chattering. If it gave you the last idea, maybe it will work again.”
“Go ahead. It won't bother me. I'm going to spend my last hours cursing the character who used a different plastic for the faceplate than he did for the rest of these suits.”
“All right,” Tazewell snapped as the geophysicist paused. “I'm supposed to ask you what you did then. You've just told me that that handkerchief of yours is a good windshield wiper; I'll admit I don't see how. I'll even admit I'm curious, if it'll make you happy.”
“It's not a handkerchief, as I said. It's a specimen bag.”
“I thought you tried those and found they didn't work — left a charge on your faceplate like the glove.”
“It did. But a remark I made myself about different kinds of plastic in the suits gave me another idea. It occurred to me that if the dust was, say, positively charged…"
“Probably was. Protons from the sun.”
“All right. Then my faceplate picked up a negative, and my suit glove a positive, so the dust was attracted to the plate.
“Then when we first tried the specimen bag, it also charged positively and left negative on the faceplate.
“Then it occurred to me that the specimen bag rubbed by the suit might go negative; and since it was fairly transparent, I could…"
“I get it! You could tie it over your faceplate and have a windshield you could see through which would repel the dust.”
“That was the idea. Of course, I had nothing to tie it with; I had to hold it.”
“Good enough. So you got a good idea out of an idle remark.”
“Two of them. The moisture one came from Shan the same way.”
“But yours worked.” Ridging grinned.
“Sorry. It didn't. The specimen bag still came out negative when rubbed on the suit plastic — at least it didn't do the faceplate any good.”
Tazewell stared blankly, then looked as though he were about to use violence.
“All right! Let's have it, once and for all.”
“Oh, it was simple enough. I worked the specimen bag — I tore it open so it would cover more area — across my faceplate, pressing tight so there wouldn't be any dust under it.”
“What good would that do? You must have collected more over it right away.”
“Sure. Then I rubbed my faceplate, dust rag and all, against Shandara's. We couldn't lose; one of them was bound to go positive. I won, and led him up the rim until the ground charge dropped enough to let the dust stick to the surface instead of us. I'm glad no one was there to take pictures, though; I'd hate to have a photo around which could be interpreted as my kissing Shandara's ugly face even through a space helmet.”
Sunspot
Ron Sacco's hand reached gently toward his switch, and paused. He glanced over at the commander, saw the latter's eyes on him, and took a quick look at the clock. Welland turned his own face away — to hide a smile? — and Sacco almost angrily thumbed the switch.
Only one of the watchers could follow the consequences in real detail. To most, the closing of the circuit was marked a split second later by a meaningless pattern on an oscilloscope screen; to “Grumpy” Ries, who had built and. installed the instrument, a great deal more occurred between the two events. His mind's eye could see the snapping of relays, the pulsing of electrical energy into the transducers in the ice outside and the hurrying sound waves radiating out through the frozen material; he could visualize their trip, and the equally hasty return as they echoed back from the vacuum that bounded the flying iceberg. He could follow them step-by step back through the electronic gear, and interpret the oscilloscope picture almost as well as Sacco. He saw it, and turned away. The others kept their eyes on the physicist.
Sacco said nothing for a moment. He had moved several manual pointers to the limits of the weird shadow on the screen, and was using his slide rule on the resulting numbers. Several seconds passed before he nodded and put the instrument back in its case.
“Well?” sounded several voices at once.
“We're not boiling off uniformly. The maximum loss is at the south pole, as you'd expect; it's about sixty centimeters since the last reading. It decreases almost uniformly to zero at about fifteen degrees north; any loss north of that has been too small for this gear to measure. You'll have to go out and use one of Grumpy's stakes if you want a reading there.”
No one answered this directly; the dozen scientists drifting in the air of the instrument room had already started arguments with each other. Most of them bristled with the phrase “I told you…" The commander was listening intently now; it was this sort of thing which had led him, days before, to schedule the radius measurements only once in twelve hours. He had been tempted to stop them altogether, but realized that it would be both impolite and impractical. Men riding a snowball into a blast furnace may not be any better off for knowing how fast the snowball is melting, but being men they have to know.
Sacco turned from his panel and called across the room.
“What are the odds now?”
“Just what they were before,” snapped Ries. “How could they have changed? We've buried ours
elves, changed the orbit of this overgrown ice cake until the astronomers were happy, and then spent our time shoveling snow until the exhaust tunnels were full so that we couldn't change course again if we wanted to. Our chances have been nailed down ever since the last second the motors operated, and you know it as well as I do.”
“I stand… pardon me, float… corrected. May I ask what our knowledge of the odds is now?” Ries grimaced, and jerked his head toward the commander.
“Probably classified information. You'd better ask the chief executive of Earth's first manned comet how long he expects his command to last.”
Welland managed to maintain his unperturbed expression, though this was as close to outright insolence as Ries had come yet. The instrument man was a malcontent by nature, at least as far as speech went; Welland, who was something of a psychologist, was fairly sure that the matter went no deeper. He was rather glad of Ries' presence, which served to bring into the open a lot of worrying which might otherwise have simmered under cover, but that didn't mean that he liked the fellow; few people, did. “Grumpy” Ries had earned his nickname well. Welland, on the present occasion, didn't wait for Sacco to repeat the question; he answered it as though Ries had asked him directly — and politely.
“We'll make it,” he said calmly. “We knew that long ago, and none of the measures have changed the fact. This comet is over two miles in diameter, and even after our using a good deal of it for reaction mass it still contains over thirty billion tons of ice. I may be no physicist, but I can integrate, and I know how much radiant heat this iceberg is going to intercept in the next week. It's not enough, by a good big factor, to boil off any thirty billion tons of the stuff around us. You all know that — you've been wasting time making a book on how much we'd still have around us after perihelion, and not one of you has figured that we lose more than three or four hundred meters from the outside. If that's not a safe margin, I don't know what is.”
“You don't know, and neither do I,” retorted Ries. “We're supposed to pass something like a hundred thousand miles from the photosphere. You know as well as I do that the only comet ever to do that came away from the sun as two comets. Nobody ever claimed that it boiled away.”
“You knew that when you signed up. No one blackmailed you. No one would — at least, no one who's here now.” The commander regretted that remark the instant he had made it, but saw no way to retract it. He was afraid for a moment that Ries might make a retort which he couldn't possibly ignore, and was relieved when the instrument man reached for a handhold and propelled himself out of the room. A moment later he forgot the whole incident as a physicist at one of the panels suddenly called out.
“On your toes, all of you! X-ray count is going up — maybe a flare. Anyone who cares, get his gear grinding!” For a moment there was a scene of confusion. Some of the men were drifting free, out of reach of handholds; it took these some seconds to get swimming. Others, more skilled in weightless maneuvering, had kicked off from the nearest wall in the direction of whatever piece of recording machinery they most cherished, but not all of these had made due allowance for the traffic. By the time everyone was strapped in his proper place, Ries was back in the room, his face as expressionless as though nothing had been said a few moments before. His eyes kept swiveling from one station to another; if anyone had been looking at him, they would have supposed he was just waiting for something to break down. He was.
To his surprise, nothing did. The flare ran its course, with instruments humming and clicking serenely and no word of complaint from their attendants. Ries seemed almost disappointed; at least Pawlak, the power plant engineer who was about the only man on board who really liked the instrument specialist, suspected that he was.
“C'mon, Grump,” was this individual's remark when everything seemed to have settled down once more. “Let's go outside and bring in the magazine from the monitor camera. Maybe something will have gone wrong with it; you said you didn't trust that remote-control system.''
Ries almost brightened.
“All right. These astronomers will probably be howling for pictures in five minutes anyway, so they can tell each other they predicted everything correctly. Suit up.” They left the room together with no one but the commander noting their departure.
There was little space outside the ship's air lock. The rocket had been brought as close to the center of the comet as measurement would permit, through a tunnel just barely big enough for the purpose. Five more smaller tunnels had been drilled, along three mutually perpendicular axes, to let out the exhaust of the fusion-powered reaction motors which were to use the comet's own mass to change its course. One other passageway, deliberately and carefully zigzagged, had been cut for personnel. Once the sunward course had been established all the tunnels except the last had been filled with “snow” — crushed comet material from near the ship. The cavern left by the removal of this and the exhaust mass was the only open space near the vessel, and even that was not too near. No one had dared weaken the structure of the big iceberg too close to the rocket; after all, one comet had been seen to divide as it passed the sun.
The monitor camera was some distance from the mouth of the tunnel — necessarily; the passage had been located very carefully. It opened in the “northern” hemisphere, as determined by direction of rotation, so that the camera could be placed at its mouth during perihelion passage and get continuous coverage. This meant, however, that in the comet's present orbital position the sun did not rise at all at the tunnel mouth. Since pictures had to be taken anyway, the camera was at the moment in the southern hemisphere, about a mile from the tunnel mouth.
Some care was needed in reaching it. A space-suited man with a mass of two hundred fifty pounds weighed something like a quarter of an ounce at the comet's surface, and could step away at several times the local escape velocity if he wished — or, for that matter, if he merely forgot himself. A dropped tool, given only the slightest accidental shove sideways, could easily go into orbit about the comet — or leave it permanently. That problem had been solved, though, after a fashion. Ries and Pawlak attached their suits together with a snap-ended coiled length of cable; then they picked up the end of something resembling a length of fine-linked chain which extended off to the southwest and disappeared quickly over the near horizon — or was it around the corner? Was the comet's surface below them, or beside or above? There was not enough weight to give a man the comforting sensation of a definite “up” and “down.” The chain had a loop at the end, and both men put one arm through this. Then Ries waved his free arm three times as a signal, and they jumped straight up together on the third wave.
It was not such a ridiculous maneuver if one remembered the chain. This remained tight as the men rose, and pulled them gradually into an arc toward the southwest.
Partway up, they emerged from the comet's shadow, the metal suits glowing like miniature suns themselves. The great, gaseous envelope of a comet looks impressive from outside, seen against a background of black space; but it means exactly nothing as protection from sunlight even at Earth's distance from the sun. At twenty million miles it is much less, if such a thing is possible. The suits were excellent reflectors, but as a necessary consequence they were very poor radiators. Their temperature climbed more slowly than that of the proverbial black body, but it would climb much higher if given time. There would be perhaps thirty minutes before the suits would be too hot for life; and that, of course, was the reason for the leap.
A one-mile walk on the surface of the comet would take far more than half an hour if one intended to stay below circular velocity; swinging to their goal as the bobs on an inverted pendulum, speed limited only by the strength of their legs, should take between ten and twelve minutes. There were rockets on their suits which could have cut even that time down by quite a factor, but neither man thought of using them. They were for emergency; if the line holding them to the comet were to part, for example, the motors would come in handy. Not until.
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* * *
They reached the peak of their arc, the chain pointing straight “down” toward the comet. Their goal had been visible for several minutes, and they had been trying to judge how close to it they would land. A direct hit was nearly impossible; even if they had been good enough to jump exactly straight up, the problem was complicated by the comet's rotation. As it turned out, the error was about two hundred yards, fairly small as such things went.
The landing maneuver was complicated-looking: but logical. Half a minute before touchdown, Ries braced his feet against Pawlak and pushed. The engineer kept his grip on the chain and stayed in “orbit” while his companion left him in an apparently straight line. About fifteen seconds sufficed to separate them by the full length of the connecting snap line; the elasticity of this promptly started them back together, though at a much lower speed than they had moved apart. Just before they touched the surface, Ries noted which side of the camera the snap line was about to land on, and deliberately whipped it so that it fell on the other side; then, when both men took up slack, it snubbed against the camera mounting. Even though both men bounced on landing — it was nearly impossible to take up exactly the right amount of energy by muscle control alone — they were secure. Ries sent a couple more loops rippling down the line and around the camera mount — a trick which had taken some practice to perfect, where there was no gravity to help — and the two men pulled themselves over to their goal. The tendency to whip around it like a mishandled yo-yo as they drew closer was a nuisance but not a catastrophe; both were perfectly familiar with the conservation of angular momentum.