The Long Mars

37

To Sally, piloting Frank in Woden, it was just another dead Mars. As seen from a high altitude the basic shape of the landscape, the tangle of Mangala Vallis below, the great rise of the Tharsis uplands to the north-east, looked much as she remembered it from spacecraft images of the Datum-Earth Mars, taken decades ago in a reality all of three million steps away.

Behind her, Frank, sleepy, grumpy since they had run out of caffeinated coffee a week back, was also unimpressed. “What the hell can he have found, if even a new set of Commandments from God on those damn monoliths wasn’t good enough?”

“It’s not visible to the naked eye,” said Willis from Thor, his voice crackling over the comms. “I’ve had optical and other scanners searching for it, from both gliders.”

Sally said, “Tell us where to look, Dad.”

“More or less east. You won’t see it, not from here. Use your screens…”

Sally fooled with her screen, looking in the direction he’d told her, exploring the bulging Tharsis province landscape under the usual featureless toffee-coloured sky. She saw a lot of horizontals, the uneven horizon itself, craters reduced to shallow ellipses by perspectives, gullies on the uplifted flanks of the volcanoes, all painted a monotonous brown by the ever-present dust. No odd shapes, no unusual colours. Then she allowed the software to scan the image for anomalies.

“Oh, my,” said Frank. Evidently he had done the same thing, about the same time. “I was looking at the ground, the landscape. The horizontals.”

“Yeah. When all the time…”

There was a vertical line, a scratch of very un-Martian powder blue, so fine and straight and true it looked like an artefact of the imaging system, a glitch. It rose up out of the landscape from some hidden root. Sally let the image pan, following the line upwards. What was this, some kind of mast, an antenna? But it rose on up into the sky—up until the imaging system reached the limit of its resolution, and the line broke up into a scatter of pixels, still dead straight, fading out like an unfinished Morse code message.

Frank said reverently, “Arthur C. Clarke, you should be seeing this. And, Willis Linsay—respect to you, sir. You found what you were looking for, all this time. I get it now.”

Willis said, only a little impatiently, “OK, let’s get the fan-boy stuff out of the way. I take it you understand what you’re looking at.”

“A beanstalk,” Frank said immediately. “Jacob’s ladder. The world tree. A stairway to heaven—”

“What about you, Sally?”

Sally closed her eyes, trying to remember. “A space elevator. Straight out of those wonders-of-the-future books you used to give me as a kid.”

“Yeah. Future wonders of my own childhood, actually. Well, here it is. A cheap way of getting to orbit, basically. You put a satellite in orbit to be the upper terminus of your elevator string. You need it to hover permanently over the lower terminus, which is on the ground. So you put it over the equator, or close to, at an orbit high enough that its period matches the rotation of the planet.”

“Where they station the communications satellites.”

“Right. Mars has about the same day as Earth, so a twenty-four-hour orbit does the trick here too. Then you just drop a cable down through the atmosphere—”

“The engineering details of that,” Frank said dryly, “are left as an exercise for the reader.”

“Then you fix it to the ground station, and you’re in business,” Willis said. “Once it’s in place, no more expensive, messy rockets to get off the planet. You get a cable-car ride to the sky, fast, cheap, clean. In principle this technology will work on any world. Any Mars. This Mars is better than our own, in fact, because it doesn’t have any pesky low-orbit moons to get in the way.”

Sally was plodding through the logic of this situation. “Let me get this straight, Dad. You predicted you were going to find a space elevator on Mars—I mean, somewhere in the Long Mars. How did you know? Who built it? How old is it? And why do you want it?”

“How did I know? It was a logical necessity, Sally. Any advanced society on a Joker Mars is going to strive to reach space, before the window of habitability closes, as close it must. And if a spacegoing culture does arise, then a space elevator is going to be something they’re going to reach for, because it’s so much easier to build here on Mars, than on Earth. Who built it? Irrelevant. Somebody was bound to, given enough time—enough chances, in the worlds of this Long Mars.

“As to why I want it—look, we need this back on Earth.

“The big challenge for a space elevator is getting hold of a cable material strong enough. On Earth, you’d need a cable twenty-two thousand miles long, and said cable has to hold up its own weight, against the pull of gravity. If you used fine-grade drawn steel wire, say, you’d only be able to raise your cable through thirty miles or so before it would pull itself apart like taffy. That’s a long way short of twenty thousand miles. In the old days there was much fancy talk of special materials with a much higher tensile strength—graphite whiskers and monomolecular filaments and nanotubes.”

“You understand this was all before Step Day,” Frank said. “When because of you, Willis, everybody got distracted by travelling stepwise instead of up and out, and the dreams of opening up space were abandoned.”

“OK, my bad. But, Sally, the point is that building an elevator on Mars is much easier than on Earth. The lower gravity, a third of Earth’s, is the key. Satellites orbit a lot slower than around Earth, at a given altitude. So the twenty-four-hour synchronous orbit is only eleven thousand miles up, not twenty-two. And you can use materials of much less tensile strength to make your cable. You see? That’s why space elevators are a much more accessible technology on Mars than on Earth. But if we can take this cable stuff home—learn its lessons, retro-engineer it to find out how it works, enhance its performance for Earth’s conditions—we’ll skip decades of development and investment.

“Think about it. What a gift for humanity, just when we need it. Once you have an elevator, access to space is so easy and cheap that everything takes off. Exploration. Huge developments like orbital power plants. Resource extraction, asteroid mining, on a vast scale. Some of the Low Earths have populations of tens of millions now, since the Yellowstone evacuations. And as they industrialize, if they start with easy access to space, they’ll be able to keep it clean and safe and green from the beginning. We could have a million-fold industrial revolution across the Long Earth, on worlds as clean as my garden in Wyoming West 1, Sally, where you used to walk me as a kid. And as for the Datum itself, given the depletion of oil and coal and mineral ores there, this is the only way the old world can ever recover.”

“You are playing Daedalus again, aren’t you?” Frank said. “I guess the historians will call it Beanstalk Day this time.”

“Things have a way of working out. Stepping did, didn’t it?”

“Sure. After a slew of social disruption, economic chaos—”

“And a billion lives saved during Yellowstone. Whatever. Anyhow this conversation is irrelevant because—”

Sally said, “Because you’re going to do this anyhow.”

“Yep. Come on, let’s head over; I want to find the root station before it’s dark. Then we’ll need to figure out how to acquire some kind of samples to take back. The cable is the thing; if we get pieces of that material the rest is detail.”

Sally pushed at her joystick; the glider climbed higher, banking to the east. “One more question, Dad. So you figured that somebody would have come up with the space elevator idea, somewhere on the Long Mars. All you had to do was keep stepping until you found it. But how did you know it would be here? I mean, geographically. If I understand it right you could grow a beanstalk anywhere along the Martian equator.”

Frank said, “Let me try to answer that one. We’ve been tracking the big Tharsis volcanoes. Right, Willis? Stick a beanstalk on top of Olympus Mons and you’re already thirteen miles up towards your goal, and above eighty per cent of the atmosphere, thus avoiding such hazards as dust storms.”

“Actually Pavonis Mons would be a better choice,” Willis said. “Not as big but slap on the equator. Yes, Frank, that was how I figured it; Tharsis had to be a site, if not the only one… Hmm.”

“What?”

“I’m getting better visuals now. Up here, out of the dusty air. As it happens the cable line doesn’t quite line up with the summit of Pavonis. Engineering details. Soon we’ll know for sure. Come on.”

They flew on, Sally tracking Willis, heading steadily east, away from the setting sun, over slowly uplifting land. The shadows speared out from the rocks and pooled deep in the craters, where Sally imagined she saw mist gather.

At last she thought she could see the cable itself with her naked eye, a baby blue scrape down a sky turning a bruised purple. She tilted her head, watching it spear up, up out of her vision, impossibly tall.

“Like a crack in the sky,” Frank said. “What’s that old song?”

“It makes me feel kind of giddy,” Sally said. “In an inverted way. I’m glad I can’t see the anchor satellite, poised up there. What if this thing broke and fell?”

“Well, the cable would wrap around the planet as it rotated, and cause a hell of a lot of damage. There was a novel called Red Mars—”

“It’s not going to fall,” Willis said.

“How do you know?” Sally snapped.

“Because it’s very ancient. If it was going to break and fall, it would have done so by now. Ancient, and lacking maintenance for a long time.”

“And how do you know that?”

“Look at the ground below.”

The featureless plain was scattered with meaningless shadows. No structure, Sally realized. No sign even of a relic.

Willis said, “Think where we are. At the foot of a space elevator, this should be the hinterland of a port that serves a major chunk of the planet. Where are the warehouses, the rail lines, the airports? Where’s the city to house the travellers and the workers? Where’s the farmland to feed them all? Oh, I know whatever race built this probably had totally different ways from the human of solving those problems. But you don’t build a space elevator unless you want to bring materials down from space, or ship goods back up into space, and you don’t do that without some kind of facility to handle stuff on the ground.”

“And there’s nothing down there,” Sally said. “How much time, Dad? How much time to erode everything to invisibility?”

“I can only guess. Millions of years? But the elevator survived all that time, the dust storms and the meteor impacts—and its own exotic hazards, such as solar storms and cable-snipping meteors further up. Whoever built that built it well…”

Suddenly the wonder of it hit her, the strangeness of the situation. Here was the product of a long-vanished indigenous civilization, about which Willis could have known nothing. Nothing about their nature, the detail of their lives—their rise, their fall, their evident extinction. And yet, from the sheer planetary geometry of Mars, he had deduced they must exist, or must have existed, and they must have built a space elevator. And he was right, here was that final monument, their last legacy, with everything else about them worn to dust. As if they had only ever existed for this one purpose, to fulfil Willis’s ambition. And he, in turn, had crossed two million Earths, the Gap, and three million copies of Mars, in the utter certainty of what he would eventually find. Not for the first time in her life she wondered what it must be like to live inside her father’s head.

“OK,” Willis said, “we’re coming up on the base of the cable. We’re still a ways short of Pavonis Mons. I guess the base could have been relocated…”

The gliders dipped towards the ground. They lit up the darkling landscape ahead with their searchlight beams, and Willis fired off a couple of flares. The artificial light made the cable gleam, a mathematical abstraction above the chaotic jumble of the plain.

At last Sally saw where the cable touched the ground—but it did not stop there. The blue line dived down into a circle of darkness, foreshortened from this distance. At first Sally thought it was a crater. Then, as the gliders flew overhead and looped past the cable itself, she realized she was looking down into a hole, a shaft that might have been a half-mile wide—smooth, symmetrical, a well of darkness.

Willis growled, “I pinged it with my radar. That’s where the cable goes, all right; that’s where the root station is. Down there. Damn thing is over twenty miles deep.”

That shocked Sally. “How deep?”

“Deep enough to contain a decent thickness of air.”

Frank the trained astronaut took over. “Deep enough that we wait until the morning before taking a look inside.”

Willis hesitated. Sally knew his instinct would be to uncoil a rope and just plunge down there with a flashlight, Martian night or no Martian night. But at length he said, “Agreed.”

Frank said, “You hotshot pilots just make sure you don’t run into that cable on the way in to landing. I’m guessing that if this thing has lasted as long as you say, Willis, then if we pick a fight with it our gliders are going to come off worst…”

And as they came down, Sally thought she saw a light in the landscape, off in the distance, far away from this beanstalk root. A single light in the dark that was extinguished when she looked again. If it had ever existed at all.