Green mars by Kim Stanley Robinson Page A

the cable continued to appear out of the planet, small rocket jets and other machinery were attached to it.
    The mass driver fired. The asteroid began to move into a new orbit.
    Years passed. The asteroid’s new orbit intersected the orbit of Mars such that the asteroid came within ten thousand kilometers of Mars, and the collection of rockets on the asteroid fired in a way that allowed the gravity of Mars to capture it, in an orbit at first highly elliptical. The jets continued to fire off and on, regularizing the orbit. The cable continued to extrude. More years passed.
    A little over a decade after the landers had first touched down, the cable was approximately thirty thousand kilometers long. The asteroid’s mass was about eight billion tons, the cable’s mass was about seven billion. The asteroid was in an elliptical orbit with a periapsis of around fifty thousand kilometers. But now all the rockets and mass drivers on both New Clarke and the cable itself began to fire, some continuously but most in spurts. One of the most powerful computers ever made sat in one of the payload bays, coordinating the data from sensors and determining what rockets should fire when. The cable, at this time pointing away from Mars, began to swing around toward it, as in the pivoting of some delicate part of a timepiece. The asteroid’s orbit became smaller and more regular.
    More rockets landed on New Clarkefor the first time since that first touchdown, and robots in them began the construction of a spaceport. The tip of the cable began to descend toward Mars. Here the calculus employed by the computer soared off into an almost metaphysical complexity, and the gravitational dance of asteroid and cable with the planet became ever more precise, moving to a music that was in a permanent ritard, so that as the great cable grew closer to its proper position, its movements became slower and slower. If anyone had been able to see the full extent of this spectacle, it might have seemed like some spectacular physical demonstration of Zeno’s paradox, in which the racer gets closer to the finish line by halving distances ... But no one ever saw the full spectacle, for no witnesses had the senses necessary. Proportionally the cable was far thinner than a human hair—if it had been reduced to a hair’s diameter, it would still have been hundreds of kilometers long—and so it was only visible for short portions of its entire length. Perhaps one might say that the computer guiding it in had the fullest sensation of it. For observers down on the surface of Mars, in the town of Sheffield, on the volcano Pavonis Mons (Peacock Mountain), the cable made its first appearance as a very small rocket, descending with a very thin leader line attached to it; something like a bright lure and a thin fishing line, being trolled by some gods in the next universe up. From this ocean-bottom perspective the cable itself followed its leader line down into the massive concrete bunker east of Sheffield with an aching slowness, until most humans simply stopped paying attention to the vertical black stroke in the upper atmosphere.
    But the day came when the bottom of the cable, firing jets to hold its position in the gusty winds, dropped down into the hole in the roof of the concrete bunker, and settled into its collar. Now the cable below the areosynchronous point was being pulled down by Mars’s gravity; the part above the areosynchronous point was trying to follow New Clarke in centrifugal flight away from the planet; and the carbon filaments of the cable held the tension, and the whole apparatus rotated at the same speed as the planet, standing above Pavonis Mons in an oscillating vibration that allowed it to dodge Deimos; all of it controlled still by the computer on New Clarke, and the long battery of rockets deployed on the carbon strand.
    The elevator was back. Cars were lifted up one side of the cable from Pavonis, and other cars were let down from New Clarke,