was difficult to estimate how distant the far side of the cliff was. Features of the cliff were perfectly clear, but structures on the opposite rim were teensy; what looked like an observatory could have fit on a pinhead.
This, he concluded, was the caldera of Pavonis Mons. They had landed at Sheffield, so really there could be no doubt about it. Therefore it was some sixty kilometres across the circle to that observatory, as Art recalled from his video documentaries, and five kilometres to the floor. And all of it completely empty, rocky, untouched, primordial—the volcanic rock as bare as if cooled the week before—nothing at all of humanity in it—no sign of terraforming. It must have looked exactly like this to John Boone, a half century before. And so … alien. And big. Art had looked into the calderas of Etna and Vesuvius, while on vacation from Tehran, and those two craters were big by Terran standards, but you could have lost a thousand of them in this, this thing, this hole …
He closed the curtains and slowly got dressed, his mouth imitating the shape of the unearthly caldera.
A friendly Praxis guide named Adrienne, tall enough to be a Martian native but possessing a strong Australian accent, collected him and took him and half a dozen other new arrivals on a tour of the town. Their rooms turned out to be on the city’s lowest level, though it wouldn’t be lowest for long: Sheffield was in the process of burrowing downward these days, to give as many rooms as possible the view onto the caldera that had so disconcerted Art.
An elevator took them up nearly fifty storeys, and let them out in the lobby of a shiny new office building. They walked out its big revolving doors and emerged on a wide grassy boulevard, and walked down it past squat buildings faced with polished stone and big windows, separated by narrow grassy side streets, and a great number of construction sites, as many buildings were still in various stages of completion. It was going to be a handsome town, the buildings mostly three and four storeys tall, getting taller as they moved south, away from the caldera rim. The green streets were crowded with people, and the occasional small tram running on narrow tracks set in the grass; there was a general air of bustle and excitement, caused no doubt by the arrival of the new elevator. A boom town.
The first place Adrienne took them was across a boulevard to the caldera rim. She led the seven newcomers out into a thin curving park, to the nearly invisible tenting that encased the town. The transparent fabrics were held in place by equally transparent geodesic struts, anchored in a chest-high perimeter wall. “The tenting has to be stronger than usual up here on Pavonis,” Adrienne told them, “because the atmosphere outside is still extremely thin. It’ll always be thinner than the lowlands, by a factor of ten.”
She led them out into a viewing blister in the tent wall, and looking down between their feet they could see through the blister’s transparent deck, straight down onto the caldera floor some five kilometres below them. People exclaimed in delicious fright, and Art bounced on the clear floor uneasily. The width of the caldera was coming into perspective for him; the north rim was just about as far away as Mt Tamalpais and the Napa hills when one descended into the San Jose airport. That was no extraordinary distance. But the depth below, now, the depth; over five kilometres, or about twenty thousand feet. “Quite a hole!” Adrienne said.
Mounted telescopes and display plaques with map drawings enabled them to spot the section of the previous version of Sheffield, now lying on the caldera floor. Art had been wrong about the caldera’s untouched primeval nature; an insignificant pile of cliff-bottom talus, with some shiny dots in it, was in fact the ruins of the original city.
Adrienne described with great gusto the destruction of the town in 2061. The falling elevator cable had, of course, crushed the suburbs east of its socket in the very first moments of the fall. But then the cable had wrapped all the way around the planet, delivering a massive second blow to the south side of town, a blow which had caused an undiscovered fault in the basalt rim to give way. About a third of the town had been on the wrong side of this fault, and had fallen the five kilometres to the caldera floor. The remaining two-thirds of the town had been knocked flat. Luckily the occupants had mostly evacuated in the four hours between the detachment of Clarke and the second coming of the cable, so loss of life had been minimised. But Sheffield had been utterly destroyed.
For many years after that, Adrienne told them, the site had lain abandoned, a wreck like so many other towns after the unrest of ’61. Most of those other towns had been left in ruins, but Sheffield’s location remained the ideal place for tethering a space elevator, and when Subarashii began organising the in-space construction of a new one in the late 2080s, construction on the ground had rapidly followed. A detailed areological investigation had found no other faults in the southern rim, which had justified rebuilding right on the edge, on the same site as before. Demolition vehicles had cleared the wreckage of the old town, shoving most of it over the rim, and leaving only the easternmost section of town, around the old socket, as a kind of monument to the disaster—also as the central element of a little tourist industry, which had clearly been an important part of the town’s income in the fallow years before an elevator had been reinstalled.
Adrienne’s next point on the tour led them out to see this preserved bit of history. They took a tram to a gate in the east wall of the tent, and then walked through a clear tube into a smaller tent, which covered the blasted ruins, the concrete mass of the old cable facility, and the lower end of the fallen cable. They walked a roped path that had been cleared of wreckage, staring curiously at the blasted ruins, the foundations and twisted pipes. It looked like the results of saturation bombing.
They came to a halt under the butt end of the cable, and Art observed it with professional interest. The big cylinder of black carbon filaments looked nearly undamaged by the fall, although admittedly this was the part that had hit Mars with the least force. The end had jammed down into the Socket’s big concrete bunker, Adrienne said, then been dragged a couple of kilometres as the cable had fallen down the eastern slope of Pavonis. That wasn’t that much of a beating for material designed to withstand the pull of an asteroid swinging beyond the areosynchronous point.
And so it lay there, as if waiting to be straightened up and put back in place: cylindrical, three storeys high, its black bulk encrusted by steel tracks and collars and the like. The tent only covered a hundred metres or so of it; after that it ran on uncovered, east along the wide rounded plateau of the rim, until it disappeared over the rim’s outer edge, which formed their horizon—they could see nothing of the planet below. But out away from the town they could see better than ever that Pavonis Mons was huge—its rim alone was an impressive expanse, a doughnut of flat land perhaps thirty kilometres wide, from the abrupt inner edge of the caldera to the more gradual drop-off down the volcano’s flanks. Nothing of the rest of Mars could be seen from their vantage point, so it seemed they stood on a high circular ring world, under a dark lavender sky.
Just to the south of them, the new Socket was like a titanic concrete bunker, the new elevator cable rising out of it like an elevator cable, standing alone as if in some version of the Indian rope trick, thin and black and straight as a plumb line dropping down from heaven—visible for only a couple of tall skyscrapers’ worth of height, at most—and, given the wreckage they stood in, and the immensity of the volcano’s bare rocky peak, as fragile-looking as if it were a single carbon nanotube filament, rather than a bundle of billions of them, and the strongest structure ever made. “This is weird,” Art said, feeling hollow and unsettled.
After their tour of the ruins, Adrienne took them back to a plaza café in the middle of the new town, where they had lunch. Here they could have been in the heart of a fashionable district in any town anywhere—it could have been Houston or Tblisi or Ottawa, in some neighbourhood where a lot of noisy construction marked a fresh prosperity. When they went back to their rooms, the subway system was likewise familiar to the eye—and when they got out, the halls of the Praxis floors were those of a fine hotel. All utterly familiar—so much so that it was again a shock to walk into his room and look out the window and see the awesome sight of the caldera—the bare fact of Mars, immense and stony, seeming to exert a kind of vacuum pull on him through the window. And in fact if the window pane were to break the pressure blowout would certainly suck him immediately into that space; an unlikely eventuality, but the image still gave him an unpleasant thrill. He closed the curtains.