The Long Mars

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 sca

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 ante

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 begi

‘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.’