Ribbon in the Sky

I

It turned out that somebody had punched the wrong button in a computer. It was in a matter in which mistakes are not permissible, but just as nothing can be manufactured without an ordinary hammer figuring somewhere in the making or the making-ready-to-make, so nothing can be done without a fallible human operator at some stage of the proceedings. And humans make mistakes casually, offhandedly, with impartial lack of either malice or predictability, so . . .

Calhoun heard the speaker say, "When the gong sounds, breakout will follow in five seconds." Then it made solemn ticking noises while Calhoun yawned and put aside the book, The Practice of Thinking. He'd been studying. Study was a necessity in his profession. Besides, it helped to pass the time in overdrive. He went to the control-desk and strapped in. Murgatroyd the tormal uncoiled his tail from about his nose and stood up from where he was catching twenty winks. He padded to the place under Calhoun's chair where there were things to grab hold of, if necessary, with one's four black paws and prehensile tail.

"Chee," said Murgatroyd conversationally, in his shrill treble.

"I agree," Calhoun told him gravely. "Stone walls do not a prison make, nor Med Ship hulls a cage. But it will be good to get outside for a change."

The speaker ticked and tocked and ticked and tocked. There was the sound of a gong. A voice said measuredly, "Five—four—three—two—one."

The ship came out of overdrive. Calhoun winced and swallowed. Nobody ever gets used to going into overdrive or coming out of it. One is hideously dizzy for an instant, and his stomach has a brief but violent urge to upchuck, and no matter how often one has experienced it, it is necessary to fight a flash of irrational panic caused by the two sensations together.

After an instant Calhoun stared about him as the vision screens came to life. They showed the cosmos outside the Med Ship. It was a perfectly normal cosmos—not at all the cosmos of overdrive—but it looked extremely wrong to Calhoun. He and Murgatroyd and the Med Ship were in emptiness. There were stars on every hand, and they were of every conceivable color and degree of brightness. But every one of them was a point of light, and a point only.

This, obviously, was not what he'd expected. These days ships do not stop to view the universe from the monstrous loneliness which is between-the-stars. All ships go into overdrive as near their port of departure as they can. Usually, it is something like five or six planetary diameters out from the local spaceport. All ships come out of overdrive as near their destinations as computation makes possible. They do not stop to look at scenery on the way. It isn't good for humans to look at stars when there are only stars to see. The sight has a tendency to make them feel small—too small. Men have been known to come out of such an experience gibbering.

Calhoun scowled at the sight of between-the-stars. This was not good. But he wasn't frightened—not yet. There should have been a flaming sun somewhere nearby, and there should have been bright crescents of half-disks or mottled cloudy planets swimming within view. The sun should have been the star Merida, and Calhoun should land in commonplace fashion on Merida II and make a routine planetary health check on a settled, complacent population, and presently he should head back to Med Headquarters with a report containing absolutely nothing of importance. However, he couldn't do any of these things. He was in purely empty space. It was appalling.

Murgatroyd jumped up to the arm of the control-chair, to gaze wisely at the screens. Calhoun continued to scowl. Murgatroyd imitated him with a tormal's fine satisfaction in duplicating a man's actions. What he saw meant nothing to him, of course. But he was moved to comment.

"Chee," he said shrilly.

"To be sure," agreed Calhoun distastefully. "That is a very sage observation, Murgatroyd. Though I deplore the situation that calls for it. Somebody's bilged on us."

Murgatroyd liked to think that he was carrying on a conversation. He said zestfully, "Chee-chee! Chee-chee-chee!"

"No doubt," conceded Calhoun. "But this is a mess! Hop down and let me try to get out of it."

Murgatroyd disappointedly hopped to the floor. He watched with bright eyes as Calhoun annoyedly went to the emergency equipment locker and brought out the apparatus designed to take care of problems like this. If the situation wasn't too bad, correcting it should be simple enough. If it was too bad, it could be fatal.

The average separation of stars throughout the galaxy, of course, is something like four or five light-years. The distance between Sol-type stars is on an average very much higher, and with certain specific exceptions habitable planets are satellites of Sol-type suns. But only a fraction of the habitable planets are colonized, and when a ship has traveled blind, in overdrive, for two months or more, its pilot cannot simply look astern and recognize his point of departure. There's too much scenery in between. Further, nobody can locate himself by the use of star-maps unless he knows where something on the star-map is with reference to himself. This makes a star-map not always useful.

The present blunder might not be serious. If the Med Ship had come out into normal space no more than eight to ten light-years from Merida, Calhoun might identify that sun by producing parallax. He could detect relative distances for a much greater range. However, it was to be hoped that his present blunder was small.

He got out the camera with its six lenses for the six vision screens which showed space in all directions. He clamped it in place and painstaking snapped a plate. In seconds he had everything above third magnitude faithfully recorded in its own color, and with relative brightnesses expressed in the size of the dots of tint. He put the plate aside and said, "Overdrive coming, Murgatroyd."

He pressed the short-hop button and there was dizziness and nausea and a flash of fear—all three sensations momentary. Murgatroyd said, "Chee" in a protesting tone, but Calhoun held down the button for an accurate five minutes. He and Murgatroyd gulped together when he let up the button again and all space whirled and nausea hit as before. He took another plate of all the heavens, made into one by the six-lensed camera. He swung the ship by ninety degrees and pressed the short-hop button a second time; more dizziness, panic and digestive revolt followed. In five minutes it was repeated as the ship came out to normal space yet again.

"Chee-chee!" protested Murgatroyd. His furry paws held his round little belly against further insult.

"I agree," said Calhoun. He exposed a third film. "I don't like it either. But I want to know where we are, if anywhere."

He set up the comparator and inserted the three plates. Each had images of each of the six vision screens. When the instrument whirled, each of the plates in turn was visible for part of a second. Extremely remote stars would not jiggle perceptibly—would not show parallax—but anything within twenty light-years should. The jiggling distance could be increased by taking the plates still farther apart. This time, though, there was one star which visibly wavered in the comparator. Calhoun regarded it suspiciously.

"We're Heaven knows where," he said dourly. "Somebody really messed us up! The only star that shows parallax isn't Merida. In fact, I don't believe in it at all. Two plates show it as a Sol-class sun and the third says it's a red dwarf!"

On the face of it, such a thing was impossible. A sun cannot be one color as seen from one spot, and another color seen from another. Especially when the shift of angle is small.

Calhoun made rough computations. He hand-set the overdrive for something over an hour's run in the direction of the one star-image which wobbled and thereby beckoned. He threw the switch. He gulped, and Murgatroyd acted for a moment as if he intended to yield unreservedly to the nausea of entering overdrive, but he refrained.

There was nothing to do but kill time for an hour. There was a microreel of starplates, showing the heavens as photographed with the same galactic coordinates from every visited Sol-class star in this sector of the galaxy. Fewer than one in forty had a colonized planet, but if the nearest had been visited before, and if the heavens had been photographed there, by matching the stars to the appropriate plate he could find out where he was. Then a star-map might begin to be of some use to him. But he had still to determine whether the error was in his astrogation unit, or in the data fed to it. If the first he'd be very bad off indeed. If the second he could still be in a fix. But there was no point in worrying while in overdrive. He lay down on his bunk and tried to concentrate again on the book he'd laid aside.

"Human error, moreover," he read, "is never purely random. The mind tends to regard stored data as infallible and to disregard new data which contradicts it . . . ." He yawned, and skipped. " . . . So each person has a personal factor of error which is not only quantitative but qualitative . . . ."

He read on and on, only half absorbing what he read. A man who has reached the status of a Med Ship man in the Interstellar Medical Service hasn't finished learning. He's still a way down the ladder of rank. He has plenty of studying before him before he gets very far.

The tape-speaker said, "When the gong sounds, breakout will be five seconds off." It began to tick-tock, slowly and deliberately. Calhoun got into the control-seat and strapped in. Murgatroyd said peevishly, "Chee!" and went to position underneath the chair. The voice said, "Five—four—three—two—one."

The little Med Ship came out of overdrive, and instantly its emergency rockets kicked violently and Murgatroyd held desperately fast. Then the rockets went off. There'd been some unguessable nearby, perhaps cometary debris at the extremist outer limit of a highly eccentric orbit. Now there was a star-field and a sun within two light-hours. If Calhoun had stared, earlier, when there was no sun in sight at all, now he gazed blankly at the spectacle before him.

There was a sun off to starboard. It was a yellow sun, a Sol-type star with a barely perceptible disk. There were planets. Calhoun saw immediately one gas-giant near enough to be more than a point, and a sliver of light which was the crescent of another more nearly in line toward the sun. But he gazed at a belt, a band, a ribbon of shining stuff which was starkly out of all reason.

It was a thin curtain of luminosity circling this yellow star. It was not a ring from the break-up of a satellite within Roche's Limit. There were two quite solid planets inside it and nearer to the sun. It was a thin, wide, luminous golden ribbon which looked like something that needed a flat iron to smooth it out. It looked somewhat like an incandescent smoke ring. It was not smooth. It had lumps in it. There were corrugations in it. An unimaginable rocket with a flat exhaust could have made it while chasing its tail around the sun. But that couldn't have happened, either.

Calhoun stared for seconds.

"Now," he said, "now I've seen everything!" Then he grunted as realization came. "Mmmmh! We're all right, Murgatroyd! It's not our computers that went wrong. Somebody fed them wrong data. We arrived where we aimed for, and there'll be a colonized planet somewhere around."

He unlimbered the electron telescope and began a search; he couldn't resist a closer look at the ribbon in space. It had exactly the structure of a slightly wobbly wrinkled belt without beginning or end. It had to be a complex of solid particles, of course, and an organization of solid particles cannot exist in space without orbital motion. However, orbits would smooth out in the course of thousands of revolutions around a primary. This was not smoothed out. It was relatively new.

"It's sodium dust," said Calhoun appreciatively. "Or maybe potassium. Hung out there on purpose. Particles small enough to have terrific surface and reflective power, and big enough not to be pushed out of orbit by light-pressure. Clever, Murgatroyd! At a guess it'll have been put out to take care of the climate on a planet just inside it. Which would be—there! Let's go look!"

He was so absorbed in his admiration that the almost momentary overdrive-hop needed for approach went nearly unnoticed. He even realized—his appreciation increasing—that this cloud of tiny particles accounted for the red dwarf appearance on one of the plates he'd taken. Light passing through widely dispersed, very small particles turns red. From one position, he'd photographed moving through this dust cloud.

The ribbon was a magnificent idea, the more magnificent because of its simplicity. It would reflect back otherwise wasted sun-heat to a too-cold planet and make it warmer. There was probably only an infinitesimal actual mass of powder in the ring, at that. Tens of scores of tons in all, hardly more.

The planet for which it had been established was the third world out. As is usual with Sol-class systems, the third planet's distance from the sun was about a hundred twenty million miles. It had ice caps covering more than two-thirds of its surface. The sprawling white fingers of glaciation marked mountain chains and highlands nearly to the equator. There was some blue sea, and there was green vegetation in a narrow belt of tropicality.

Calhoun jockeyed the Med Ship to position for a landing call. This was not Merida II; there should be a colony here! That glowing ribbon had not been hung out for nothing.

"Med Ship Aesclipus Twenty," he said confidently into the space-phone mike. "Calling ground. Requesting coordinates for landing. My mass is fifty tons. Repeat, five-oh tons. Purpose of landing, to find out where I am and how to get where I belong."

There was a clicking. Calhoun repeated the call. He heard murmurings which were not directed into the transmitter on the planet. They were speaking in the transmitter room aground. He heard an agitated: "How long since a ship landed?" Another voice was saying fiercely, "Even if he doesn't come from Two City or Three City, who knows what sickness . . ." There was sudden silence, as if a hand had been clapped over the microphone below. Then a long pause. Calhoun made the standard call for the third time.

"Med Ship Aesclipus Twenty," said the space-phone speaker grudgingly, "you will be allowed to land. Take position." Calhoun blinked at the instructions he received. The coordinates were not the normal galactic ones. They gave the local time at the spaceport, and the planetary latitude. He was to place himself overhead. He could do it, of course, but the instructions were unthinkable. Galactic coordinates had been used ever since Calhoun knew anything about such matters. But he acknowledged the instructions. Then the voice from the speaker said truculently: "Don't hurry! We might change our minds! And we have to figure settings for an only fifty-ton ship, anyhow."

Calhoun's mouth dropped open. A Med Ship was welcome everywhere, these days. The Interstellar Medical Service was one of those over-worked, understaffed, kicked-around organizations that are everywhere taken for granted. Like breathable air, nobody thought to be grateful for it, but nobody was suspicious of it, either.

The suspicion and the weird coordinates and the ribbon in space combined to give Calhoun a highly improbable suspicion. He looked forward with great interest to this landing. He had not been ordered to land here, but he suspected that a Med Ship landing was a long, long time overdue.

"I forgot to take star-pictures," he told Murgatroyd, "but a ribbon like this would have been talked about if it had been reported before. I doubt star-pictures would do us any good. The odds are that our only chance to find out where we are is to ask." Then he shrugged his shoulders. "Anyhow this won't be routine!"

"Chee!" agreed Murgatroyd profoundly.