Part 2

"I think," he said, "that there ought to be a change in maximum no-drain voltage. I'd like to check it."

The operator shrugged again. He pressed buttons under a phone-plate.

"Shift to reserve power," he commanded, when a face appeared in the plate. "Gotta check no-drain juice."

"What for?" demanded the face in the plate.

"You-know-who's got ideas," said the grid operator scornfully. "Maybe we've been skimping something. Maybe there's some new specification we didn't know about. Maybe anything! But shift to reserve power."

The face in the screen grumbled. Bordman swallowed. It was not a Survey officer's privilege to maintain discipline. And anyhow, there was no particular virtue in discipline here and now. He watched the current-demand dial. It stood a little above normal day-drain, which was understandable. The outside temperature was down. There was more power needed to keep the dwellings warm, and there was always a lot of power needed in the mine the colony had been formed to exploit. The mine had to be warmed for the men who worked to develop it.

The current-demand needle dropped abruptly, hung steady, and dropped again and again as additional parts of the colony's power uses were switched to reserve. The needle hit bottom. It stayed there.

Bordman had to walk around the standby man to get at the voltmeter. It was built around standard, old-fashioned vacuum-tubes, and tested it. He pushed in the contact plugs, read the no-drain voltage, licked his lips, and made a note. He reversed the leads, so it would read backward. He took another reading. He drew in his breath very quietly.

"Now I want the power turned on in sections," he told the operator. "The mine first, maybe. It doesn't matter. But I want to get voltage readings at different power take-offs."

The operator looked pained. He spoke with unnecessary elaboration to the face in the phone-plate, and grudgingly went through the process by which Bordman measured the successive drops in voltage with power drawn from the ionosphere. The current available from a layer of ionized gas is, in effect, the current-flow through a conductor with marked resistance. It is possible to infer a gas's ionization from the current it yields.

The cold-lock door opened. Riki Herndon came in, panting a little.

"There's another message from home," she said sharply. Her voice seemed strained. "They picked up our answering-beam and are giving the information you asked for."

"I'll be along," said Bordman. "I just got some information here."

He got into his cold-garments again, and followed her out of the control-hut.

"The figures from home aren't good," said Riki, when mountains visibly rose on every hand around them. "Ken says they're much worse than he thought. The rate of decline in the solar constant's worse than we figured or could believe."

"I see," said Bordman, inadequately.

"It's absurd!" said Riki angrily. "There've been sunspots and sunspot cycles all along--I learned about them in school. I learned about a four-year and a seven-year cycle, and that there were others. They should have known, they should have calculated in advance! Now they talk about sixty-year cycles coming in with a hundred-and-thirty-year cycle to pile up with all the others.... What's the use of scientists if they don't do their work right and twenty million people die of it?"

Bordman did not consider himself a scientist, but he winced. Riki raged as they moved over the slippery ice. Her breath was an intermittent cloud about her shoulders, and there was white frost on the front of her cold-garments. Even so quickly the moisture of her breath congealed.

He held out his hand quickly as she slipped, once.

"But they'll beat it!" said Riki in a sort of angry pride. "They're starting to build more landing-grids, back home. Hundreds of them! Not for ships to land by, but to draw power from the ionosphere! They figure that one ship-size grid can keep nearly three square miles of ground warm enough to live on. They'll roof over the streets of cities and pile snow on top for insulation. Then they'll plant food-crops in the streets and gardens, and do what hydroponic growing they can. They're afraid they can't do it fast enough to save everybody, but they'll try!"

Bordman clenched his hands inside their bulky mittens.

"Well?" demanded Riki, "Won't that do the trick?"

"No."

"Why not?"

"I just took readings on the grid, here. The voltage and the conductivity of the layer we draw power from, both depend on ionization. When the intensity of sunlight drops, the voltage drops and the conductivity drops too. It's harder for less power to flow to the area the grid can tap--and the voltage pressure is lower to drive it."

"Don't say any more!" cried Riki. "Not another word!"

Bordman was silent. They went down the last small slope, and passed the opening of the mine, a great drift which bored straight into the mountain. Looking into it, they saw the twin rows of brilliant roof-lights going toward the heart of the stony monster.

They had almost reached the village when Riki said in a stifled voice:

"How bad is it?"

"Very," admitted Bordman. "We have here the conditions the home planet will have in two hundred days. Originally we could draw less than a fifth the power they count on from a grid on Lani II."

Riki ground her teeth.

"Go on!" she said.

"Ionization here is down ten per cent," said Bordman. "That means the voltage is down, somewhat more. A great deal more. And the resistance of the layer is greater. Very much greater. When they need power most, on the home planet, they won't draw more from a grid than we do now. It won't be enough."

They reached the village. There were steps to the cold-lock of Herndon's office-hull. They were ice-free, because like the village walk-ways they were warmed to keep frost from depositing on them. Bordman made a mental note.

In the cold-lock, the warm air pouring in was almost stifling. Riki said defiantly:

"You might as well tell me now!"

"We usually can draw one-fifth as much power, here, as the same sized grid would yield on your home world," he said. "We are drawing--call it sixty per cent of normal. A shade over one-tenth of what they expect to draw when the real cold hits them. Their estimates are nine times too high. One grid won't warm three square miles of city. About a third of one is closer. But--"

"That won't be the worst," said Riki in a choked voice. "Is that right? How much good will a grid do?"

Bordman did not answer.

The inner cold-lock door opened. Herndon sat at his desk, even paler than before, listening to the hash of noises that came out of the speaker. He tapped on the desk-top, quite unconscious of the action. He looked almost desperately at Bordman.

"Did she tell you?" he asked in a numb voice. "They hope to save maybe half the population. All the children anyhow...."

"They won't," said Riki bitterly.

"Better go transcribe the new stuff that's come in," said her brother. "We might as well know what it says."

Riki went out of the office. Bordman shed his cold-garments. He said:

"The rest of the colony doesn't know what's up yet. The operator at the grid didn't certainly. But they have to know."

"We'll post the messages on the bulletin board," said Herndon. "I wish I could keep it from them. It's not fun to live with. I--might as well not tell them just yet."

"To the contrary," insisted Bordman. "They've got to know right away! You're going to issue orders and they'll need to understand how urgent they are."

Herndon looked hopeless.

"What's the good of doing anything?" When Bordman frowned, he added: "Seriously, is there any use? You're all right. A Survey Ship's due to take you away. It's not coming because they know there's something wrong, but because your job should be finished about now. But it can't do any good! It would be insane for it to land at home. It couldn't carry away more than a few dozen refugees, and there are twenty million people who're going to die. It might offer to take some of us, but I don't think many of us would go. I wouldn't. I don't think Riki would."

"I don't see--"

"What we've got right here," said Herndon, "is what they're going to have back home. And worse. But there's no chance for us to keep alive here! You are the one who pointed it out. I've been figuring, and the way the solar-constant curve is going--I plotted it from the figures they gave us--it couldn't possibly level out until the oxygen, anyhow, is frozen out of the atmosphere here. We aren't equipped to stand anything like that, and we can't get equipped. There isn't equipment to let us stand it indefinitely! Anyhow, the maximum cold conditions will last two thousand days back home--six Earth-years. And there'll be storage of cold in frozen oceans and piled-up glaciers. It'll be twenty years before home will be back to normal in temperature, and the same here. Is there any point in trying to live--just barely to survive--for twenty years before there'll be a habitable planet to go back to?"

Bordman said irritably:

"Don't be a fool! Doesn't it occur to you that this planet is a perfect experiment station, two hundred days ahead of the home world, where ways to beat the whole business can be tried? If we can beat it here, they can beat it there!"

Herndon said:

"Can you name one thing to try here?"

"Yes," snapped Bordman. "I want the walk-heaters and the step-heaters outside turned off. They use power to keep walk-ways clear of frost and door-steps not slippery. I want to save that heat!"

Herndon said, "And when you've saved it, what will you do with it?"

"Put it underground to be used as needed!" Bordman said. "Store it in the mine! I want to put every heating-device we can contrive to work in the mine, to heat the rock. I want to draw every watt the grid will yield and warm up the inside of the mountain while we can draw power to do it with. I want the deepest part of the mine too hot to enter! We'll lose a lot of heat, of course. It's not like storing electric power. But we can store heat now, and the more we store the more will be left when we need it!"

Herndon thought. Presently he stirred slightly.

"Do you know, that is an idea...." He looked up. "Back home there was a shale-oil deposit up near the ice-caps. It wasn't economical to mine it. So they put heaters down in bore-holes and heated up the whole shale deposit. Drill-holes let out the hot oil vapors to be condensed. They got out every bit of oil without disturbing the shale. And then the shale stayed warm for years! Farmers bulldozed soil over it and raised crops with glaciers all around them. That could be done again. They could be storing up heat back home!"

Then he drooped.

"But they can't spare power to warm up the ground under cities. They need all the power they've got to build roofs.... And it takes time to build grids."

Bordman snapped:

"Yes, if they're building regulation ones. By the time they were finished they'd be useless. The ionization here is dropping already. But they don't need to build grids that will be useless later. They can weave cables together on the ground and hang them in the air by helicopters. They wouldn't hold up a landing ship for an instant, but they'll draw power right away. They'll even power the helis that hold them up! Of course, they'll have defects; they'll have to come down in high winds, for example. They won't be too dependable. But they can put heat in the ground to come out under roofs, to grow food by, to save lives by. What's the matter with them?"

Herndon stirred again. His eyes ceased to be dull and lifeless.

"I'll give the orders for turning off the sidewalks. And I'll send what you just said back home. They should like it."

He looked respectfully at Bordman.

"I guess you know what I'm thinking right now," he said.

Bordman flushed. He felt that Herndon was unduly impressed. Herndon didn't see that the device wouldn't solve anything. It would merely postpone the effects of a disaster. It could not possibly prevent them.

"It ought to be done," he said. "There'll be other things to be done, too."

"Then when you tell them to me," said Herndon, "they'll get done! I'll have Riki put this into that pulse-code you explained to us and she'll get it off right away."

He stood up.

"I didn't explain the code to her!" insisted Bordman. "She was already translating it when you gave her my suggestion!"

"All right," said Herndon. "I'll get this sent back at once!"

He hurried out of the office. _This_, thought Bordman irritably, _is how reputations are made, I suppose. I'm getting one._ But his own reaction was extremely inappropriate. If the people of Lani II did suspend helicopter-supported grids of wire in the atmosphere, they could warm masses of underground rock and stone and earth. They could establish what were practically reservoirs of life-giving heat under their cities. They could contrive that the warmth from below would rise only as it was needed. _But_--

Two hundred days to conditions corresponding to the colony-planet. Then two thousand days of minimum-heat conditions. Then very, very slow return to normal temperature, long after the sun was back to its previous brilliance. They couldn't store enough heat for so long. It couldn't be done. It was ironic that in the freezing of ice and the making of glaciers the planet itself could store cold.

Also, there would be monstrous storms and blizzards on Lani II as cold conditions got worse. The wire-grids could be held aloft for shorter and shorter periods, and each time they would pull down less power than before. Their effectiveness would diminish even faster than the need for effectiveness increased.

Bordman felt even deeper depression as he worked out the facts. His proposal was essentially futile. It would be encouraging, and to a very slight degree and for a certain short time it would palliate the situation on the inner planet. But in the long run its effect would be zero.

He was embarrassed, too, that Herndon was so admiring. Herndon would tell Riki that he was marvelous. She might--though cagily--be inclined to agree. But he wasn't marvelous. This trick of a flier-supported grid was not new. It had been used on Saril to supply power for giant peristaltic pumps emptying a polder that had been formed inside a ring of indifferently upraised islands.

_All I know_, thought Bordman bitterly, _is what somebody's showed me or I've read in books. And nobody's showed or written how to handle a thing like this!_

He went to Herndon's desk. Herndon had made a new graph of the solar-constant observations forwarded from home. It was a strictly typical curve of the results of coinciding cyclic change. It was the curve of a series of frequencies at the moment when they were all precisely in phase. From this much one could extrapolate and compute.

Bordman took a pencil, frowning. His fingers clumsily formed equations and solved them. The result was just about as bad as it could be. The change in brightness of the sun Lani would not be enough to be observed on Kent IV, the nearest other inhabited world, when the light reached there four years from now. Lani would never be classed as a variable star, because the total change in light and heat would be relatively minute. The formula for computing planetary temperatures is not simple. Among its factors are squares and cubes of the variables. Worse, the heat radiated from a sun's photosphere varies not as the square or cube, but as the fourth power of its absolute temperature.

Bordman's computations were not pure theory. The data came from Sol itself, where alone in the galaxy there had been daily solar-constant measurements for three hundred years. The rest of his deductions were based ultimately on Earth observations, too. Most scientific data had to refer back to Earth to get an adequate continuity. And there could be no possible doubt about the sunspot data, because Sol and Lani were of the same type and nearly equal size.

Using the figures on the present situation, Bordman reluctantly arrived at the fact that here, on this already-frozen world, the temperature would drop gradually until CO_{2} froze out of the atmosphere. When that happened, the temperature would plummet until there was no really significant difference between it and that of empty space. It is carbon dioxide which is responsible for the greenhouse effect, by which a planet is in thermal equilibrium only at a temperature above its surroundings, as a greenhouse in sunlight is warmer than the outside air.

The greenhouse effect would vanish soon on the colony-world. When it vanished on the mother planet....

Bordman found himself thinking, _if Riki won't leave when the Survey ship comes, I'll resign from the Service. I'll have to if I'm to stay. And I won't go unless she does._

* * * * *

"If you want to come, it's all right," said Bordman ungraciously.

He waited while Riki slipped into the bulky cold-garments that were needed out-of-doors in the daytime, and were doubly necessary at night. There were heavy boots with inches-thick insulating soles, made in one piece with the many-layered trousers. There was an air-puffed, insulated over-tunic with its hood and mittens which were a part of the sleeves.

"Nobody goes outside at night," she said when they stood together in the cold-lock.

"I do," he told her. "I want to find out something."

The outer door opened and he stepped out. He held his arm for her, because the steps and walk-way were no longer heated. Now they were covered with a filmy layer of something which was not frost, but a faint bloom of powder--microscopic snow-crystals frozen out of the air by the unbearable chill of night.

There was no moon, of course, yet the ice-clad mountains glowed faintly. The drone-hulls arranged in such an orderly fashion were dark against the frosted ground. There was silence, stillness, the feeling of ancient quietude. No wind stirred anywhere. Nothing moved, nothing lived. The soundlessness was enough to crack the ear-drums.

Bordman threw back his head and gazed at the sky for a very long time. Nothing. He looked down at Riki.

"Look at the sky," he commanded.

She raised her eyes. She had been watching him. But as she gazed upward she almost cried out. The sky was filled with stars in innumerable variety. But the brighter ones were as stars had never been seen before. Just as the sun in daylight had been accompanied by its sun-dogs--pale phantoms of itself ranged about it--so the brighter distant suns now shone from the center of rings of their own images. They no longer had the look of random placing. Those which were most distinct were patterns in themselves, and one's eyes strove instinctively to grasp the greater pattern in which such seeming artifacts must belong.

"Oh--beautiful!" cried Riki softly.

"Look!" he insisted. "Keep looking!"

She continued to gaze, moving her eyes about hopefully. It was such a sight as no one could have imagined. Every tint and every color, every possible degree of brightness appeared. And there were groups of stars of the same brilliance which almost made triangles, but not quite. There were rose-tinted stars which almost formed an arc, but did not. And there were arrays which were almost lines and nearly formed squares and polygons, but never actually achieved them.

"It's beautiful," said Riki. "But what must I look for?"

"Look for what isn't there," he ordered.

She looked, and the stars were unwinking, but that was not extraordinary. They filled all the firmament, without the least space in which some tiny sparkle of light was not to be found. But that was not remarkable, either. Then there was a vague flickering grayish glow somewhere, indefinite. It vanished. Then she realized.

"There's no aurora!" she exclaimed.

"That's it," said Bordman. "There've always been auroras here. But no longer. We may be responsible. I wish I thought it wise to turn everything back to reservoir power for a while. We could find out. But we can't afford it."

"I looked at it when we first landed," admitted Riki. "It was unbelievable. But it was terribly cold, out of shelter. And it happened every night, so I said to myself I'd look tomorrow, and then tomorrow again. So it got so I never looked at all."

Bordman kept his eyes where that faint gray flickering had been. And, once one realized, it was astonishing that the former nightly play of ghostly colors should be absent.

"The aurora," he said, "happens in the very upper limits of the air, fifty--seventy--ninety miles up, when God-knows-what emitted particles from the sun come streaking in, drawn by the planet's magnetic field. The aurora's a phenomenon of ions. We tap the ionosphere a long way down from where it plays, but I'm wondering if we stopped it."

"We?" said Riki, shocked. "We humans?"

"We tap the ions of their charges," he said somberly, "that the sunlight made by day. We're pulling in all the power we can. I wonder if we've drained the aurora of its energy, too."

Riki was silent. Bordman gazed, still searching. But he shook his head.

"It could be," he said in a carefully detached voice. "We didn't draw much power by comparison with the amount that came. But the ionization is an ultra-violet effect. Atmospheric gases don't ionize too easily. After all, if the solar constant dropped a very little, it might mean a terrific drop in the ultra-violet part of the spectrum--and that's what makes ions of oxygen and nitrogen and hydrogen and such. The ion-drop could easily be fifty times as great as the drop in the solar constant. And we're drawing power from the little that's left."

Riki stood very still. The cold was horrible. Had there been a wind, it could not have been endured for an instant. But the air was motionless. Yet its coldness was so great that the inside of one's nostrils ached, and the inside of one's chest was aware of chill. Even through the cold-garments there was the feeling as of ice without.

"I'm beginning," said Bordman, "to suspect that I'm a fool. Or maybe I'm an optimist. It might be the same thing. I could have guessed that the power we could draw would drop faster than our need for power increased. If we've drained the aurora of its light, we're scraping the bottom of the barrel. And it's a shallower barrel than one would suspect."

There was stillness again. Riki stood mousy-quiet. _When she realizes what this means_, thought Bordman grimly, _she won't admire me so much. Her brother's built me up. But I've been a fool, figuring out excuses to hope. She'll see it._

"I think," said Riki, "that you're telling me that after all we can't store up heat to live on, down in the mine."

"We can't," agreed Bordman. "Not much, nor long. Not enough to matter."

"So we won't live as long as Ken expects?"

"Not nearly as long," said Bordman. "He's hoping we can find out things to be useful back on Lani II. But we'll lose the power we can get from our grid long before even their new grids are useless. We'll have to start using our reserve power a lot sooner. It'll be gone--and us with it--before they're really in straits for living-heat."

Riki's teeth began to chatter.

"This sounds like I'm scared," she said angrily, "but I'm not! I'm just freezing. If you want to know, I'd a lot rather have it the way you say. I won't have to grieve over anybody, and they'll be too busy to grieve for me.... Let's go inside while it's still warm."

He helped her back into the cold-lock, and the outer door closed. She was shivering uncontrollably when the warmth came pouring in.

They went into Herndon's office. He came in as Riki was peeling off the top part of her cold-garments. She still shivered. He glanced at her and said to Bordman: