Part 4

"High in oxygen," said he. "The CO_{2}, drops to the bottom, being heavier. Then, too, the air is thinner up here because centrifugal force swings the whole out to the rim. Out there we are so used to 'down' that here, a half mile above--or to the center, rather--we have trouble in saying, technically, what we mean. Watch!"

He left Arden standing and walked rapidly around the inside of the cylinder. Soon he was standing on the steel plates directly over her head. She looked up, and shook her head.

"I know why," she called, "but it still makes me dizzy. Come down from up there or I'll be sick."

Channing made a neat dive from his position above her head. He did it merely by jumping upward from his place toward her place, apparently hanging head down from the ceiling. He turned a neat flip-flop in the air and landed easily beside her. Immediately, for both of them, things became right-side-up again.

Channing opened the door to the room marked: "Air Plant." He stepped in, snapped on the lights, and gasped in amazement.

"Hell!" he groaned. The place was empty. Completely empty. Absolutely, and irrevocably vacant. Oh, there was some dirt on the floor and some trash in the corners, and a trail of scratches on the floor to show that the life giving air plant had been removed, hunk by hunk, out through another door at the far end of the room.

"Whoa, Tillie!" screamed Don. "We've been stabbed! Arden, get on the type and have ... no, wait a minute until we find out a few more things about this!"

* * * * *

They made record time back to the office level. They found Burbank in his office, leaning back, and talking to someone on the phone.

Channing tried to interrupt, but Burbank removed his nose from the telephone long enough to snarl, "Can't you see I'm busy? Have you no manners or respect?"

Channing, fuming inside, swore inwardly. He sat down with a show of being calm and folded his hands over his abdomen like the famed statue of Buddha. Arden looked at him, and for all the trouble they were in, she couldn't help giggling. Channing, tall, lanky, and strong, looked as little as possible like the popular, pudgy figure of the Sitting Buddha.

A minute passed.

Burbank hung up the phone.

"Where does Venus Equilateral get its air from?" snapped Burbank.

"That's what I want--"

"Answer me, please. I'm worried."

"So am I. Something--"

"Tell me first, from what source does Venus Equilateral get its fresh air?"

"From the air plant. And that is--"

"There _must_ be more than one," said Burbank thoughtfully.

"There's only one."

"There must be more than one. We couldn't live if there weren't," said the Director.

"Wishing won't make it so. There is only one."

"I tell you, there must be another. Why, I went into the one up at the axis day before yesterday and found that instead of a bunch of machinery, running smoothly, purifying air, and sending it out to the various parts of the station, all there was was a veritable jungle of weeds. Those weeds, Mr. Channing, looked as though they must have been put in there years ago. Now, where did the air-purifying machinery go?"

Channing listened to the latter half of Burbank's speech with his chin at half-mast. He looked as though a feather would knock him clear across the office.

"I had some workmen clear the weeds out. I intend to replace the air machinery as soon as I can get some new material sent from Terra."

Channing managed to blink. It was an effort. "You had workmen toss the weeds out--" he repeated dully. "The weeds--"

There was silence for a minute, Burbank studied the man in the chair as though Channing were a piece of statuary. Channing was just as motionless. "Channing, man, what ails you--" began Burbank. The sound of Burbank's voice aroused Channing from his shocked condition.

Channing leaped to his feet. He landed on his heels, spun, and snapped at Arden: "Get on the type. Have 'em slap as many oxy-drums on the fastest ship as they've got! Get 'em here at full throttle. Tell 'em to load up the pilot and crew with gravanol and not to spare the horsepower! Scram!"

Arden gasped. She fled from the office.

"Burbank, what did you think an air plant was?" snapped Channing.

"Why, isn't it some sort of purifying machinery?" asked the wondering Director.

"What better purifying machine is there than a plot of grass?" shouted Channing. "Weeds, grass, flowers, trees, alfalfa, wheat, or anything that grows and uses chlorophyll. We breathe oxygen, exhale CO_{2}. Plants inhale CO_{2}, and exude oxygen. An air plant means just that. It is a specialized type of Martian sawgrass that is more efficient than anything else in the system for inhaling dead air and revitalizing it. And you've tossed the weeds out!" Channing snorted in anger. "We've spent years getting that plant so that it will grow just right. It got so good that the CO_{2} detectors weren't even needed. The balance was so adjusted that they haven't even been turned on for three or four years. They were just another source of unnecessary expense. Why, save for a monthly inspection, that room isn't even opened, so efficient is the Martian sawgrass. We, Burbank, are losing oxygen!"

The Director grew white. "I didn't know," he said.

"Well, you know now. Get on your horse and do something. At least, Burbank, stay out of my way while I do something."

"You have a free hand," said Burbank. His voice sounded beaten.

Channing left the office of the Director and headed for the chem lab. "How much potassium chlorate, nitrate, sulphate, and other oxygen-bearing compounds have you?" he asked. "That includes mercuric oxide, spare water, or anything else that will give us oxygen if broken down."

There was a ten-minute wait until the members of the chem lab took a hurried inventory.

"Good," said Channing. "Start breaking it down. Collect all the oxygen you can in containers. This is the business! It has priority! Anything, no matter how valuable, must be scrapped if it can facilitate the gathering of oxygen. God knows, there isn't by half enough--not even a tenth. But try, anyway."

* * * * *

Channing headed out of the chemistry laboratory and into the electronics lab. "Jimmie," he shouted, "get a couple of stone jars and get an electrolysis outfit running. Fling the hydrogen out of a convenient outlet into space and collect the oxygen. Water, I mean. Use tap water, right out of the faucet."

"Yeah, but--"

"Jimmie, if we don't breathe, what chance have we to go on drinking? I'll tell you when to stop."

"O.K., Doc," said Jimmie.

"And look. As soon as you get that running, set up a CO_{2} indicator and let me know the percentage at the end of each hour! Get me?"

"I take it that something has happened to the air plant?"

"It isn't functioning," said Channing shortly. He left the puzzled Jimmie and headed for the beam-control room. Jimmie continued to wonder about the air plant. How in the devil could an air plant cease functioning unless it were--_dead_! Jimmie stopped wondering and began to operate on his electrolysis set-up furiously.

Channing found the men in the beam-control room worried and ill at ease. The fine co-ordination that made them expert in their line was ebbing. The nervous work demanded perfect motor control, excellent perception, and a fine power of reasoning. The perceptible lack of oxygen at this high level was taking its toll already.

"Look, fellows, we're in a mess. Until further notice, take five-minute shifts. We've got about thirty hours to go. If the going gets tough, drop it to three-minute shifts. But, fellows, keep those beams centered until you drop!"

"We'll keep 'em going if we have to call our wives up here to run 'em for us," said one man. "What's up?"

"Air plant's sour. Losing oxy. Got a shipload coming out from Terra, be here in thirty hours. But upon you fellows will rest the responsibility of keeping us in touch with the rest of the system. If you fail, we could call for help until hell freezes us all in--and no one would hear us!"

"We'll keep 'em rolling," said a little fellow who had to sit on a tall stool to get even with the controls.

* * * * *

Channing looked out of the big, faceted plexiglass dome that covered the entire end of the Venus Equilateral Station. "Here messages go in and out," he mused. "The other end brings us things that take our breath away."

Channing was referring to the big air lock at the other end of the station, three miles away, right through the center.

At the center of the dome, there was a sighting 'scope. It kept Polaris on a marked circle, keeping the station exactly even with the Terrestrial North. About the periphery of the dome, looking out across space, the beam-control operators were sitting, each with a hundred-foot parabolic reflector below his position, outside the dome, and under the rim of the transparent howl. These reflectors shot the interworld signals across space in tight beams, and the men, half the time anticipating the vagaries of space-warp, kept them centered on the proper, shining speck in that field of stars.

Above his head the stars twinkled. Puny man, setting his will against the monstrous void. Puny man, dependent upon atmosphere. "'Nature abhors a vacuum,' said Torricelli," groaned Channing. "Nuts! If nature abhorred a vacuum, why did she make so much of it?"

* * * * *

Arden Westland entered the apartment without knocking. "I'd give my right arm up to here for a cigarette," she said, marking above the elbow with the other hand.

"Na-hah," said Channing. "Can't burn oxygen."

"I know. I'm tired, I'm cold, and I'm ill. Anything you can do for a lady?"

"Not as much as I'd like to do," said Channing. "I can't help much. We've got most of the place stopped off with the air-tight doors. We've been electrolyzing water, baking KClO_{3} and everything else we can get oxy out of. I've a crew of men trying to absorb the CO_{2} content and we are losing. Of course, I've known all along that we couldn't support the station on the meager supplies we have on hand. But we'll win in the end. Our microcosmic world is getting a shot in the arm in a few hours that will re-set the balance."

"I don't see why we didn't prepare for this emergency," said Arden.

"This station is well balanced. There are enough people here and enough space to make a little world of our own. We can establish a balance that is pretty darned close to perfect. The imperfections are taken care of by influxes of supplies from the system. Until Burbank upset the balance, we could go on forever, utilizing natural purification of air and water. We grow a few vegetables and have some meat critters to give milk and steak. The energy to operate Venus Equilateral is supplied from the uranium pile. Atomic power, if you please. Why should we burden ourselves with a lot of cubic feet of supplies that would take up room necessary to maintain our balance? We are not in bad shape. We'll live, though we'll all be a bunch of tired, irritable people who yawn in one another's faces."

"And after it is over?"

"We'll establish the balance. Then we'll settle down again. We can take up where we left off," said Don.

"Not quite. Venus Equilateral has been seared by fire. We'll be tougher and less tolerant of outsiders. If we were a closed corporation before, we'll be tighter than a vacuum-packed coffee can afterwards. And the first bird that cracks us will get hissed at."

Three superliners hove into sight at the end of thirty-one hours. They circled the station, signaling by helio. They approached the air lock end of the station and made contact. The air lock was opened and space-suited figures swarmed over the South End Landing Stage. A stream of big oxygen tanks was brought into the air lock, admitted, and taken to the last bulwark of huddled people on the fourth level.

From one of the ships there came a horde of men carrying huge square trays of dirt and green, growing sawgrass.

For six hours, Venus Equilateral was the scene of wild, furious activity. The dead air was blown out of bad areas, and the hissing of oxygen tanks was heard in every room. Gradually the people left the fourth level and returned to their rightful places. The station rang with laughter once more, and business, stopped short for want of breath, took a deep lungful of fresh air and went back to work.

The superliners left. But not without taking a souvenir. Francis Burbank went with them. His removal notice was on the first ship, and Don Channing's appointment as Director of Venus Equilateral was on the second.

Happily he entered the Director's office once more. He carried with him all the things that he had removed just a few short weeks before. This time he was coming to stay.

Arden entered the office behind him. "Home again?" she asked.

"Yop," he grinned at her. "Open file B, will you, and break out a container of my favorite beverage?"

"Sure thing," she said.

There came a shout of glee. "Break out four glasses," she was told from behind. It was Walt Franks and Joe.

It was Arden that proposed the toast. "Here's to a closed corporation," she said. They drank on that.

She went over beside Don and took his arm. "You see?" she said, looking up into his eyes. "We aren't the same. Things have changed since Burbank came, and went. Haven't they?"

"They have," laughed Channing. "And now that you are my secretary, it is no longer proper for you to shine up to me like that. People will talk."

"What's he raving about?" asked Joe.

Channing answered, "It is considered highly improper for a secretary to make passes at her boss. Think of what people will say; think of his wife and kids."

"You have neither."

"People?" asked Channing innocently.

"No--you ape--the other."

"Maybe so," nodded Don, "but it is still in bad taste for a secretary--"

"No man can use that tone of voice on me!" stormed Arden with a glint in her eye. "I resign! You can't call me a secretary!"

"But Arden--darling--"

Arden relaxed into the crook of Channing's arm. She winked at Walt and Joe. "Me--," she said, "I've been promoted!"

_Interlude:_

_Maintaining Communications through the worst of interference was a type of problem in which dire necessity demanded a solution. Often there are other problems of less demanding nature. These are sometimes called "projects" because they may be desirable but are not born of dire necessity._

_Barring interference, the problem of keeping communication with another planet across a hundred million miles of interplanetary space is partially solved by the fact that you can see your target! Keeping the cross-hairs in a telescope properly centered is a technical job more arduous than difficult._

_But seeing a spacecraft is another problem. Consider the relative sizes of spacecraft and planet. Where Terra is eight thousand miles in diameter, the largest of spacecraft is eight hundred feet long. Reduced to a common denominator and a simple ratio, it reads that the earth is 50,000 times as large as the largest spacecraft. Now go outside and take a look at Venus. At normal distances, it is a mote in the sky. Yet Venus is only slightly smaller than the earth. Reduce Venus by fifty thousand times, and no astronomer would ever suspect its existence._

_Then take the invisible mote and place it in a volume of 1,000,000,000,000,000,000 cubic miles and he who found the needle in a haystack is a piker by comparison._

_It could have been lives at stake that drove the job out of the "project" class and into the "necessity" stage. The fact that it was ebb and flow of a mundane thing like money may lower the quality of glamor._

_But there it was--a problem that cried out for a solution; a man who was willing to pay for the attempt; and a group of technicians more than happy to tackle the job._

CALLING THE EMPRESS

The chart in the terminal building at Canalopsis Spaceport, Mars, was a huge thing that was the focus of all eyes. It occupied a thirty-by-thirty space in the center of one wall, and it had a far-flung iron railing about it to keep the people from crowding it too close, thus shutting off the view. It was a popular display, for it helped to drive home the fact that space travel was different from anything else. People were aware that their lives had been built upon going from one fixed place to another place, equally immobile. But on interplanet travel, one left a moving planet for another planet, moving at a different velocity. You found that the shortest distance was not a straight line but a space curve involving higher mathematics.

The courses being traveled at the time were marked, and those that would be traversed in the very near future were drawn upon the chart, too; all appropriately labeled. At a glance, one could see that in fifty minutes and seventeen seconds the _Empress of Kolain_ would take off from Mars, which was the red disk on the right, and she would travel along the curve so marked to Venus, which was almost one hundred and sixty degrees clockwise around the Sun. People were glad of the chance to go on this trip because the Venus Equilateral Relay Station would come within a telescope's sight on the way.

_The Empress of Kolain_ would slide into Venus on the day side; and a few hours later she would lift again to head for Terra, a few degrees ahead of Venus and about thirty million miles away.

Precisely on the zero-zero, the _Empress of Kolain_ lifted upward on four tenuous pillars of dull-red glow and drove a hole in the sky. The glow was almost lost in the bright sunshine, and soon it died. The _Empress of Kolain_ became a little world in itself, and would so remain until it dropped onto the ground at Venus, almost two hundred million miles away.

Driving upward, the _Empress of Kolain_ could not have been out of the thin Martian atmosphere when a warning bell rang in the telephone and telespace office at the terminal. The bell caught official ears, and all work was stopped as the personnel of the communications office ran to the machine to see what was so important that the "immediate attention" signal was rung.

Impatiently the operator waited for the tape to come clicking from the machine. It came, letter by letter, click by click, at fifty words per minute. The operator tore the strip from the machine and read aloud: "Hold _Empress of Kolain_. Reroute to Terra direct. Will be quarantined at Venus. Whole planet in epidemic of Venusian Fever."

"Snap answer," growled the clerk. "Tell 'em: 'Too little and too late. _Empress of Kolain_ left thirty seconds before warning bell. What do we do now?'"

The operator's fingers clicked madly over the keyboard. Across space went the signal, across the void to the Relay Station. It ran through the Station's mechanism and went darting to Terra. It clicked out as sent in the offices of Interplanet Transport. A vice president read the message and swore roundly. He swore in three Terran languages, in the language of the Venusians, and even managed to visualize a few choice remarks from the Martian Pictographs that were engraved on the Temples of Canalopsis.

"Miss Deane," he yelled at the top of his voice. "Take a message! Shoot a line to Channing on Venus Equilateral. Tell him: '_Empress of Kolain_ on way to Venus. Must be contacted and rerouted to Terra direct. Million dollars' worth of Martian Line Moss aboard; will perish under quarantine. Spare no expense.' Sign that 'Keg Johnson, Interplanet.'"

"Yes, Mr. Johnson," said the secretary. "Right away."

More minutes of light-fast communication. Out of Terra to Luna, across space to Venus Equilateral. The machines clicked and tape cleared away from the slot. It was pasted neatly on a sheet of official paper, stamped _rush_, and put in a pneumatic tube.

* * * * *

As Don Channing began to read the message, Williams on Mars was chewing worriedly on his fourth fingernail, and Vice President Keg Johnson was working on his second. But Williams had a head start and therefore would finish first. Both men knew that nothing more could be done. If Channing couldn't do it, nobody could.

Channing finished the 'gram and swore. It was a good-natured swear-word, far from downright vilification, though it did consign certain items to the nether regions. He punched a button with some relish, and a rather good-looking woman entered. She smiled at him with more intimacy than a secretary should, and sat down.

"Arden, call Walt, will you?"

Arden Westland smiled. "You might have done that yourself," she told him. She reached for the call button with her left hand, and the diamond on her finger glinted like a pilot light.

"I know it," he answered, "but that wouldn't give me the chance to see you."

"Baloney," said Arden. "You just wait until next October. I'll be in your hair all the time then."

"By then I may be tired of you," said Channing with a smile. "But until then, take it or leave it." His face grew serious, and he tossed the message across the table to her. "What do you think of that?"

Arden read, and then remarked: "That's a huge order, Don. Think you can do it?"

"It'll cost plenty. I don't know whether we can contact a ship in space. It hasn't been done to date, you know, except for short distances."

The door opened without a knock and Walt Franks walked in. "Billing and cooing?" he asked. "Why do you two need an audience?"

"We don't," answered Don. "This was business."

"For want of evidence, I'll believe that. What's the dope?"

"Walt, what are the chances of hooking up with the _Empress of Kolain_, which is en route from Mars to Venus?"

"About equal to a snowball--you know where," said Franks looking slyly at Arden.

"Take off your coat, Walt. We've got a job."

"You mean--Hey! Remind me to quit Saturday."

"This is dead in earnest, Walt." Don told the engineer all he knew.

"Boy, this is a job I wouldn't want my life to depend on. In the first place, we can't beam a transmitter at them if we can't see 'em. And in the second place, if we did, they couldn't receive us."

"We can get a good idea of where they are and how they're going," said Channing. "That is common knowledge."

"Astronomy is an exact science," chanted Franks. "But by the time we figure out just where the _Empress of Kolain_ is with respect to us at any given instant we'll all be old men with gray beards. She's crossing toward us on a skew curve--and we'll have to beam it past Sol. It won't be easy, Don. And then if we do find them, what do we do about it?"

"Let's find them first and then work out a means of contacting them afterwards."

"Don," interrupted Arden, "what's so difficult?"

Franks fell backward into a chair. Don turned to the girl and asked: "Are you kidding?"

"No. I'm just ignorant. What is so hard about it? We shoot beams across a couple of hundred million miles of space like nothing and maintain communications at any cost. What should be so hard about contacting a ship?"

"In the first place, we can see a planet, and they can see us, so they can hold their beams. A spaceship might be able to see us, but they couldn't hold a beam on us because of the side sway. We couldn't see them until they are right upon us and so we could not hope to hold a beam on them. Spaceships _might_ broadcast, but you have no idea what the square law of radiated power will do to a broadcast signal when millions upon millions of miles are counted in. A half million watts on any planet will not quite cover the planet as a service area on broadcast frequencies. But there's a lot of difference between covering a few stinking miles of planet and a volume the size of the Inner Solar System. So they don't try it. A spaceship may as well be on Rigel as far as contacting her in space goes.