by Hal Clement
Ries quickly opened the camera, removed the exposed part of the film in its take-up cartridge and replaced and re-threaded another, checked the mounting for several seconds, and the job was done. The trip back was like that out, except for the complication that their landing spot was not in sunlight and control was harder. Five minutes after getting their rope around the pole at the tunnel mouth, they were in the ship. There was no speed limit inside the comet.
Once they were inside the air lock, Ries' prophecy was promptly fulfilled. Someone called for pictures before his suit had been off for two minutes. Pawlak watched his friend's blood pressure start up, and after a moment's calculation decided that intervention was in order — Grumpy couldn't be allowed too many fights.
“Go develop the stuff,” he said. “I'll calm this idiot down.”
For a moment it looked as though Ries would rather do his own arguing; then he relaxed, and vanished toward the instrument shop. Pawlak homed on the voice of the complaining astrophysicist, and in the three minutes it took Ries to process the film managed to make the fellow feel properly apologetic. This state of affairs lasted for about ten seconds after the film was delivered.
A group of six or seven scientists were waiting eagerly and had it in a projector almost instantly. For a few seconds after the run started there was silence; then a babble of expostulating voices arose. The general theme seemed to be, “Where's that instrument maker?”
Ries had not gone far, and when he appeared did not seem surprised. He didn't wait to be asked any questions, but took advantage of the instant silence which greeted his entrance.
“Didn't get your flare, did you? I didn't think so. That camera has a half-degree field, and the sun is over two degrees wide seen from here…"
“We know that!” Sacco and two or three others spoke almost together. “But the camera was supposed to scan the whole sun automatically whenever it was turned on from here, and keep doing it until we turned it off!”
“I know. And it didn't scan. I thought it hadn't when I was getting the film…"
“How could you tell? Why didn't you fix it? Or did you? What was wrong, anyway? Why didn't you set it up right in the first place?”
“I could tell that there hadn't been enough film exposed for the time it was supposed to be on. As for fixing it out there, or even finding out what was wrong — don't sound any more idiotic than you can help. It'll have to be brought into the shop. I can't promise how long it'll take to fix it until I know what's wrong.”
The expostulation rose almost to a roar at this last remark. The commander, who alone of the group had been silent until now, made a gesture which stilled the others.
“I know it's hard to promise, but please remember one thing,” he said. “We're twenty million miles from the sun; we'll be at perihelion in sixty-seven hours. If we pass it without that camera, we'll be missing our principal means of correlating any new observations with the old ones. I don't say that without the camera we might as well not be here, but…"
“I know it,” growled Ries. “All right. I knew we should have laid down a walk cable between here and the blasted thing when we first set it up, but with people talking about time and shortage of anchoring pins and all that tripe—''
“I think that last was one of your own points,” interjected the commander. “However, we have better things to do than fix blame. Tell us what help you need in getting the camera back to the ship.”
An hour later, the device came in through the air lock. Its mass had demanded a slight modification in travel technique; if the chain had broken during a “swing” the rockets would not have been able to return men and camera both to the comet, in all likelihood. Instead of swinging, therefore, the workers had pulled straight along the chain, building up speed until they reached its anchorage and then slowing down on the other side by applying friction to the chain as it unwound behind them. An extra man with a line at the tunnel mouth had simplified the stopping problem on the return trip with the camera.
Four hours later still, Ries had taken the camera completely apart and put it together again, and was in a position to say that there had been nothing wrong with it. He was not happy about this discovery, and the scientists who heard his report were less so. They were rather abusive about it; and that, of course, detonated the instrument man's temper.
“All right, you tell me what's wrong!” he snapped at last. “I can say flatly that nothing is broken or out of adjustment, and it works perfectly in here. Any genius who's about to tell me that in here isn't out there can save his breath. I know it, and I know that the next thing to do is take it back out and see if it still works. That's what I'm doing, if I can spare the time from listening to your helpful comments.” He departed abruptly, donned his suit, and went outside with the instrument but without Pawlak. He had no intention of returning to the original camera site, and needed no help. The tunnel mouth was “outside” enough, he felt.
It took several more hours to prove that he was right. At first, the trouble refused to show itself. The camera tracked beautifully over any sized square of sky that Ries chose to set into its control. Then after half an hour or more, the size of the square began to grow smaller no matter what he did with the controls. Eventually it reached zero. This led him into its interior, as well as he could penetrate it in a spacesuit, but no information was forthcoming. Then, just to be tantalizing, the thing started to work again. On its own, as far as Ries could tell. He was some time longer in figuring out why.
Eventually he came storming back into the ship, fulminating against anyone who had had anything to do either with designing or selecting the device. He was a little happier, since the trouble was demonstrably not his own fault, but not much. He made this very clear to the waiting group as soon as his helmet was off.
“I don't know what genius indulged his yen for subminiaturization,” he began, “but he carried it too far. I suppose using a balanced resistance circuit in a control is sensible enough; it'll work at regular temperatures, and it'll work at comet temperatures. The trouble is it won't work unless the different segments are near the same temperature; otherwise the resistors can't possibly balance. When I first took the thing outside, it worked fine; it was at ship's temperature. Then it began to leak heat into the comet, and went crazy. Later on, with the whole thing cooled down to comet temperature, it worked again. Nice design!”
“But it had been outside for days before…" began someone, and stopped as he realized what had happened. Ries pounced on him just the same.
“Sure — outside in the sunlight. Picking up radiant heat on one side, doing its best to get to equilibrium at a couple of hundred degrees. Conducting heat out into the ice four or five hundred degrees colder on the other side. Nice, uniform — aach!”
“Can't a substitute control be devised?” cut in the commander mildly. “That's your field, after all. Surely you can put something together…"
“Oh, sure. In a minute. We're just loaded with spare parts and gear; rockets always are. While I'm at it I'll try to make the thing wristwatch size so it will fit in the available space— all we need is a research lab's machine shop. I'll do what I can, but you won't like it. Neither will I.” He stormed out to his own shop.
“I'll buy his last remark, anyway,” muttered someone. Agreement was general but not too loud.
At fifteen million miles from the sun, with another meter or so boiled off the comet's sunlit surface, Ries emerged with his makeshift. He was plainly in need of sleep, and in even worse temper than usual. He had only one question to ask before getting into his suit.
“Shouldn't the sun be starting to show near the tunnel mouth by now?”
“One of the astronomers did a little mental arithmetic.
“Yes,” he answered. “You won't need to travel anywhere to test the thing. Do you need any help?”
“What for?” growled Ries in his usual pleasant fashion, and disappeared again. The astronomer shrugged. By the time conversation ha
d gotten back to normal the instrument specialist and his camera were in the air lock.
Taking the heavy device out through the tunnel offered only one danger, and that only in the last section — the usual one of going too fast and leaving the comet permanently. To forestall the risk of forcing people to pay final respects to him and regret the camera, he made full use of the loops of safety cable which had been anchored in the tunnel wall. He propped the instrument at the tunnel mouth facing roughly north, and waited for sunrise. This came soon enough. It was the display characteristic of an airless world, since the coma was not dense enough to scatter any light to speak of. The zodiacal light brightened near the horizon; then it merged into pearly corona; then a brilliant crimson eruptive arch prominence appeared, which seemed worth a picture or two to the nonprofessional; and finally came the glaring photosphere on which the test had to be made. It was here that another minor problem developed.
The photosphere, area for angular area, was of course no brighter than when seen from just above Earth's atmosphere; but it was no fainter either, and Ries could not look at it to aim his camera. The only finder on the latter was a direct-view collimating sight, since it was designed for automatic control. After a moment's thought, Ries decided that he could handle this situation too, but, since his solution would probably take longer than the sun would be above the horizon, he simply ran the camera through a few scanning cycles, aiming it by the shape of its own shadow. Then he anchored the machine in the tunnel mouth and made his way back to the ship.
Here he found what he wanted with little difficulty — a three-inch-square interference filter. It was not of the tunable sort, though of course its transmission depended on the angle of incidence of the light striking it, but it was designed for sixty-five hundred Angstroms and would do perfectly well for what he had in mind.
Before he could use it, though, another problem had to be solved. Almost certainly the lining up of the camera and its new control — that is, making sure that the center of its sweep field agreed with the line laid down by the collimator sight — would take quite a while. At fifteen million miles from the sun, one simply doesn't work for long with only a spacesuit as protection. The expedition had, of course, been carefully planned so that no one would have to do any such thing; but the plans had just graduated from history to mythology. Grumpy Ries was either going to work undisturbed in full sunlight, probably for one or two whole hours, or spend twenty minutes cooling off in the tunnel for every ten he spent warming up outside it; and that last would add hours and hours to the job time — with the heating period growing shorter with each hour that passed. A parabolic orbit has one very marked feature; its downhill half is very steeply downhill, and speed builds up far too quickly for comfort. It seemed that some means of working outside, if one could be found, would pay for itself. Ries thought he could find one.
He was an artisan rather than a scientist, but he was a good artisan. A painter knows pigments and surfaces, a sculptor knows metal and stone; Ries knew basic physics. He used his knowledge.
Limited as the spare supplies were, they included a number of large rolls of aluminum foil and many spools of wire. He put these to use, and in an hour was ready with a six-foot-square shield of foil, made in two layers a couple of inches apart, the space between them stuffed with pulverized ice from the cavern. In its center was mounted the filter, and beside this a hole big enough to take the camera barrel. The distance between the two openings had been measured carefully; the filter would be in front of the camera sight.
Characteristically, he showed the device to no one. He made most of it outside the ship, as a matter of fact; and when it was done he towed it rather awkwardly up the tunnel to the place where the camera was stored. Incredibly, twenty minutes later the new control was aligned, the camera mounted firmly on its planned second base at the tunnel mouth, and a control line was being run down the tunnel to the ship. With his usual curtness he reported completion of the job; when the control system had been tested from inside, and the method Ries had used to accomplish the task wormed out of him, the reaction of the scientists almost had him smiling.
Almost; but a hardened grouch doesn't change all at once — if ever.
Ten million miles from Sol's center. Twenty-one hours to go— people were not yet counting minutes. The sun was climbing a little higher above the northern horizon as seen from the tunnel mouth, and remaining correspondingly longer in view each time it rose. Some really good pictures were being obtained; nothing yet which couldn't have been taken from one of the orbital stations near Earth.
Five million miles. Ten hours and fifty minutes. Ries stayed inside, now, and tried to sleep. No one else had time to. Going outside, even to the mouth of the tunnel, was presumed impossible, though the instrument maker had made several more shields. Technically, they were within the corona of the sun, though only of its most tenuous outlying zones — there is, of course, a school of thought that considers the corona as extending well past the earth's orbit. None of the physicists were wasting time trying to decide what was essentially a matter of definition; they were simply reading and recording every instrument whose field of sensitivity seemed to have the slightest bearing on their current environment, and a good many which seemed unlikely to be useful, but who could tell?
Ries was awake again when they reached the ninety degree point — one quarter of the way around the sun from perihelion. The angular distance the earth travels in three months. Slightly over one million miles from the sun's center. Six hundred thousand miles from the photosphere. Well within anyone's definition of the corona; within reach of a really healthy eruptive prominence, had any been in the way. One hour and eighteen minutes from their closest approach — or deepest penetration, if one preferred to put it that way. Few did.
They were hurtling, at some three hundred ten miles per second, into a region where the spectroscope claimed temperatures above two million degrees to exist, where ions of iron and nickel and calcium wandered about with a dozen and more of their electrons stripped away, and where the electrons themselves formed almost a gas in their own right, albeit a highly tenuous one.
It was that lack of density on which the men were counting. A single ion at a “temperature” of two million degrees means nothing; there isn't a human being alive who hasn't been struck by vast numbers of far more energetic particles. No one expected to pick up any serious amount of heat from the corona itself.
The photosphere was another matter. It was an opaque, if still gaseous, “surface” which they would approach within one hundred fifty thousand miles — less than its own diameter by a healthy factor. It had a radiation equilibrium temperature of some six thousand degrees, and would fill a large solid angle of sky; this meant that black-body equilibrium temperature at their location would not be much below the same value. The comet, of course, was not a black body — and did not retain even the heat which it failed to reflect. The moment a portion of its surface was warmed seriously, that portion evaporated, taking the newly acquired heat energy with it. A new layer, still only a few degrees above absolute zero, was exposed in its turn to the flood of radiation.
That flood was inconceivably intense, of course; careless, nonquantitative thought could picture the comet's vanishing under that bombardment like a snowball in a blast furnace — but the flood wasn't infinite. A definite, measurable amount of energy struck the giant snowball; a definite amount was reflected; a definite, measurable amount was absorbed and warmed up and boiled away the ices of water and ammonia and methane that made it up.
And there was a lot to boil away. Thrust-acceleration ratios had long ago given the scientists the mass of their shelter, and even at a hundred and fifty thousand miles a two-and-a-half-mile-thick bar of sunlight will take some time to evaporate thirty-five billion tons of ice. The comet would spend only a little over twenty-one hours within five million miles of the sun, and unless several physicists had misplaced the same decimal point, it should last with plenty to
spare. The twelve-hour rule on Sacco's echo sounder had been canceled now, and its readings were common knowledge; but none of them caused anxiety.
In they drove. No one could see out, of course; there was nothing like the awed watching of an approaching prominence or gazing into the deceptively pitlike area of a sunspot of which many of them had unthinkingly dreamed. If they could have seen a sunspot at all, it would have been as blinding as the rest of the photosphere — human eyes couldn't discriminate between the two orders of overload. For all any of them knew, they might be going through a prominence at any given second; they wouldn't be able to tell until the instrument records were developed and reduced. The only people who could “see” in any sense at all were the ones whose instruments gave visible as well as recorded readings. Photometers and radiometers did convey a picture to those who understood them; magnetometers and ionization gauges and particle counters meant almost as much; but spectrographs and interferometers and cameras hummed and clicked and whirred without giving any clues to the nature of the meals they were digesting. The accelerometers claimed their share of watchful eyes — if there were any noticeable drag to the medium outside, all bets on the comet's future and their own were off — but nothing had shown so far.
They were nineteen minutes from perihelion when a growing sense of complacency was rudely shattered. There was no warning — one could hardly be expected at three hundred twenty-five miles a second.
One instant they were floating at their instruments, doing their allotted work, at peace with the universe; the next there was a violent jolt, sparks flew from exposed metal terminals, and every remote indicator in the vessel went dead.
For a moment there was silence; the phenomenon ended as abruptly as it had started. Then there was a mixed chorus of yells, mostly of surprise and dismay, a few of pain. Some of the men had been burned by spark discharges. One had also been knocked out by an electric shock, and it was fortunate that the emergency lights had not been affected; they sprang automatically to life as the main ones failed, and order was quickly restored. One of the engineers applied mouth-to-mouth respiration to the shock victim — aesthetic or not, it is the only sort practical in the weightless condition — and each of the scientists began trouble shooting.