Phase Space

Scale: Exp 2

Oliver Greenberg was bored.

He was actually glad to get the call from Gita Weissman about the balky rock splitter in Shaft Seven, even though the lost time would mean they weren’t going to make quota this month.

At least it made a change from the usual CELSS problems, CELSS for closed environment and life-support systems, a term nobody used except him any more. Even after a century, nobody had persuaded a pea plant to grow nice straight roots in microgravity, and the loss from the mass loops in the hydroponic tanks continued at a stubborn couple of per cent a month, despite the new generation of supercritical water oxidizers they used to reduce their solid wastes.

It’s still about pea plants and plumbing, he thought dismally.

He started clambering into his skinsuit, hauling the heavy fabric over his useless legs.

He took a last glance around the glass-wall displays of his hab module. It shocked him when the displays showed him he was the only one of Ra’s two thousand inhabitants on the surface.

Well, hell, it suited him out here, even if it had stranded him in this lonely assignment, monitoring the systems that watched near-Ra space. Most of the inhabitants of Ra had been born up here, and lived their lives encased in the fused-regolith walls of old mine shafts. They didn’t know any better.

Greenberg, though, preferred to keep a weather eye on the stars, unchanged since his Iowa boyhood. He even liked seeing Earth swim past on its infrequent close approaches, like a blue liner on a black ocean, approaching and receding. It made him nostalgic. Even if he couldn’t go home any more.

Suited up, he shut down the glass-wall displays. The drab green walls of the hab module were revealed, with their equipment racks and antique bathroom and galley equipment and clumsy-looking up-down visual cues. This was just an old Space Station module, dragged out here and stuck to the surface of Ra-Shalom, covered over with a couple of metres of regolith. He was tethered in the rim shadow of Helin Crater, the place he’d landed on that first jaunt in the Ehricke. And that had been all of a hundred years ago, my God.

He pushed his way through the diaphragm lock set in the floor of his hab module. He was at the top of one of Shaft Two, one of the earliest they’d dug out, with those first clumsy drill-blast-muck miners. It was a rough cylinder ten metres across, lined with regolith glass and hung with lamps and tethers; it descended beneath him, branching and curving.

He grabbed hold of a wall spider, told it his destination, and let it haul him on down into the tunnel along its stay wires.

Thus, clinging to his metal companion, he descended into the heart of Ra-Shalom.

His legs dangled uselessly, and so he set his suit to tuck them up to his chest. He was thinking of taking the surgeons’ advice, and opting for amputation. What the hell. He was a hundred and fifty years old, give or take; he wasn’t going to start complaining.

Anyhow, apart from that, the surgeons were preserving him pretty well. They were treating him to a whole cocktail of growth hormones and DHEA and melatonin treatments and beta-carotene supplements, not to mention telomere therapy and the glop those little nano-machines had painted on the surface of his shrivelled-up brain to keep him sharp.

These guys were good at keeping you alive.

This asteroid was small. A stable population was important, and a heavy investment in training needed a long payback period to be effective. So the birth rate was low, and a lot of research was directed to human longevity.

He understood the logic. But still, he missed the sound of children playing, every now and again. The youngsters here didn’t seem to mind that, which made them a little less than human, in his view. But maybe that was part of the adjustment humans were having to make, as they learned to live off-Earth.

In fact he missed his own kids, his daughters, even though, astonishingly, they were now both old ladies themselves.

The surgeons had even managed to repair some of the cumulative microgravity damage he’d suffered over the years. For instance, his skeletal and cardiac muscles were deeply atrophied. Until they found a way to stabilize it, his bone calcium had continued to wash out in his urine, at a half per cent a month. At last, the surgeons said, the inner spongy bone, the trabeculae, had vanished altogether, without hope of regeneration.

He never had been too conscientious about his time in the treadmills. It had left him a cripple, on Earth.

So, at age eighty, he’d left Earth.

Even then they had been closing down the cans – the early stations starting with Mir and the Space Station, that had relied completely on materials brought up from Earth. In retrospect it just didn’t make sense to haul material up from Earth at great expense, when it was already here, just floating around in the sky, in rocks like Ra.

So he’d come back to come out to Ra-Shalom, the place that had made him briefly famous.

He suspected the surgeons liked to have him around, as a control experiment. The youngsters were heavily treated from birth, up here, to enable them to endure a lifetime of microgravity. Not a one of them could land on Earth, of course, or even Mars. But not too many of them showed a desire to do any such thing.

The wall spider, scuttling busily, brought him to the mine face, the terminus of Shaft Seven. It was a black, dusty wall, like a coal face. There was dust everywhere, floating in the air.

There were five or six people here, in their brightly coloured skinsuits, scraping their way around the stalled miner. Their suits were seamless and without folds, to guard against the dust. They were all tall, their limbs spindly as all hell, their skeletal structures pared down as far as they would go.

The miner itself clung to the walls with a dozen fat legs, with the balky rock splitter itself held out on a boom before the face. It was a radial-axial design with a percussive drill, powered by hydraulics, with a drill feed, a radial splitter and a loader. But for now it was inert.

One of the youngsters came up to him. It was Gita Weissman, Mike’s granddaughter. She grinned through her translucent faceplate; her skinsuit was what they used to call Day-Glo orange.

‘Dust,’ she said. ‘It’s always the dust.’

‘Yeah.’

‘Grab a pump. We want to get this baby back on line or we’ll miss quota again.’

He started to prepare a vacuum-pump tube.

The ‘dust’ was surface rock flour: half of it invisible to the naked eye, abrasive, and electrostatically sticky. Despite their best efforts it had gotten all the way through the interior workings of Ra, coating every surface.

A lot of Earthbound experience was worthless up here. No machine, for example, which used its own weight for leverage was going to be any use. Nevertheless, some terrestrial technologies, like coal gasification, had proven to be good bases for development of systems that gave a low capital investment and a fast payback.

Greenberg remembered how they’d celebrated when the ore processors had first started up, and water had come trickling out of crushed and heated asteroid cinder. It had touched, he supposed, something deep and human, some atavistic response to the presence of water here, the stuff of life in this ancient rock from space.

Whatever, it had been one terrific party.

And this rock, and many others like it, had proven to be as rich as those old sci-fi-type dreamers, who Greenberg used to laugh at, had hoped. Ra was fat with water – twenty per cent of its mass, locked up in hydrate minerals and in subsurface ice. It exported kerogen, a tarry petrochemical compound found in oil shales, which contained a good balance of nutrients: primordial soup, they called it. Ra pumped out hydrogen, methane, kerosene and methanol for propellants, and carbon monoxide, hydrogen and methane combinations to support metal processing …

And so on.

Ra was just a big volatiles warehouse floating around in the sky. And with the big surface mass drivers that Greenberg called softball pitchers, Ra products were shipped to places that were volatile-poor – like Mars, lacking nitrogen, and the Moon, dry as a desert. It was a lot cheaper to export them from a rock floating around up here than from all the way at the bottom of Earth’s gravity well.

To Greenberg’s great surprise, Ra’s inhabitants had become rich.

The first justification for opening up the rocks had been to make them serve as short-term resource factories to aid in the colonization of the Moon, Mars and beyond. But it wasn’t working out like that. Sure, the gravity well colonies were in place, but they were hardly thriving; they were always going to be dependent on key volatiles shipped in from somewhere else. And they didn’t have much to trade; Ra could purchase high-grade metals much more cheaply from other rocks.

There were actually more humans living in the rocks now than on the Moon or Mars. And Ra had more trade with other rocks than anybody else – even Earth …

He saw there was one articulated joint on the splitter boom that was giving particular problems; its prophylactic cover had been taken off, revealing a knobby joint with big, easily replaced parts, already half-dismantled, like the knee joint of a T Rex.

The youngsters were talking about more advances in technology. Like nanotech miners which would chomp their way through the rock without any human intervention at all. Greenberg kind of hoped it wouldn’t be for a while, though; he preferred machinery big enough to see, and wrestle with. It gave him a purpose, a reason to use the upper-body strength he’d brought up from Earth.

The workers got out of the way of him, and, whistling, he moved into the balky joint with his vacuum line.

Screw Mars, he thought as he worked; he liked it here.

The remnant of the cloud moulded itself into a flattened, rotating disc. Solid particles condensed: ices of water and hydrocarbons in the cooler, outer rim, but only rocky debris in the hot, churning heart of the nebula. Planetesimals formed, massive, misshapen bodies that collided and accreted as they raced around the new sun.

And, out of the collisions, planets grew: rocky worlds in the hot centre, volatile-fat giants further out. A powerful wind blew from the sun, violently ejecting the amniotic remnants of the birth cloud. Planetesimals rained down on the surfaces of the new worlds, leaving scars that would persist for billions of years.

The gravity of young Jupiter plucked at the belt of planetesimals further in, preventing their coalescence into larger bodies. So, in the gap between Jupiter and Mars, the planetesimals survived as asteroids: rocky chunks closest to the sun, volatile-rich snowballs at the outer rim, moulded by impacts with each other, melted by radioactivity and electrical induction.

And it was to the asteroids that the starship came: after billions of years drifting like a seed between the stars, still running from the supernova, exhausted, depleted, its ancient machinery cradling the generations that swarmed within, evolving, never understanding their plight.

Scale: Exp 3

The nanobugs woke him; with reluctance he swam up from dreams of sunlit days with his daughters on the beaches of Galveston.

He emerged into a gritty, unwelcome reality. Here he was: half a man, with his whole lower body replaced by the gleaming box he called his PMU, pipes and tubes everywhere, still rattling around inside his clumsy old hab module.

Not that there could be much left of his original home. That old NASA stuff had mostly worn out after a decade, let alone a thousand years. But the Weissmans, or anyhow the robots they’d assigned to keeping him alive, quietly rebuilt this old box around him, just as they rebuilt him continually, nanobugs crawling through his body while he slept away the years.

Well, the hell with it. He dug out a packet of food – the label reassured him it was chicken soup, and as far as he was concerned that was what it was – and he shoved it into the rehydration drawer of his galley.

He moved to a window, the little nitrogen reaction-control squirters on his PMU hissing softly. The window gave onto a shaft cut through the regolith, which had a massive lid that would swing down on him in case of a solar flare or some such. It gave him a good view of the surface of Ra-Shalom, and a slice of the night side of Earth, and a handful of stars.

Water-blue light glared out of Ra.

When he’d first come here, Ra had been just a lump of dirty carbonaceous stone. Now, the old craters and ravines transformed into a patchwork of windows, roofed over with some kind of smart membrane.

Greenberg could see into the lens-like surface of one of the crater windows. And right now, a few minutes from the aerobraking of Toutatis, the Weissmans were swimming up from the big spherical ocean they were building in the hollowed-out interior of Ra, swimming up to watch a light show hardly any of them understood, probably.

The Weissmans came in a variety of shapes. There were even still a few standard-issue four-limbed humans around. But the most common morphology was something like a mermaid, with the legs – useless, heavy distractions in microgravity – replaced by a kind of fish tail, useful for swimming around in the air, or the interior ocean. A lot of them had gills and never came out of the water at all, and some were covered in fur that streamlined and warmed their bodies.

The Weissmans had done away with every part of the body which wasn’t needed in microgravity. And some had gone further. Some didn’t have hands, or arms. In an age of ubiquitous and one hundred per cent reliable machinery – machinery which could manufacture other machinery – human beings, it seemed, didn’t need to be toolmakers any more.

To Greenberg, they looked like nothing so much as seals.

It was their choice, or their progenitors anyhow. But what Greenberg couldn’t figure was what they did all day.

Greenberg himself still had work to do, in these rare intervals of wakefulness: monitoring Ra’s external systems, checking the import of volatile and metal-rich cargoes.

But maybe the Weissmans were just being kind. There were probably gigantic smart systems that backed up every action he took. He was a kind of museum piece, he supposed: the first human to rendezvous with an asteroid, all those years ago, a living totem for the Weissmans of Ra.

He finished the soup and let go of the packet, and a domestic bot – a fussy little bastard like a trash can with attitude thrusters – came hissing out of its corner and grabbed the bag.

Greenberg felt sour, grumpy and isolated.

He studied Earth, which swam past on one of its closest approaches to the rock in years.

He remembered from his first orbital missions aboard Shuttle, all those centuries ago, how the coastal rims of the continents would just glow with artificial light. Greenberg had supposed, then, that it would go on, that the Earth would just get richer and fatter and brighter.

But it hadn’t worked out that way. Earth, in fact, grew darker every time he looked.

Once the expansion into the near-Earth rocks had begun, it wasn’t long before a move further out followed: first to Phobos and Deimos, the captured asteroids that circled Mars, and then out into the main belt itself. Vesta, one of the biggest of the main belt rocks, had been the first to be extensively colonized, and now it was the hub of further expansion, little archipelagos of busy mines and colonization, scattered across the belt.

And, so Greenberg understood, there were some pioneers who had gone even farther afield: to the comets out in the Oort Cloud, and the Kuiper Belt, where billions of ice moons the size of Ganymede swam through the darkness.

Of course the techniques they used nowadays made Ra look primitive. Those universal fabricators, for instance, that sucked in asteroid ore at one end and pumped out whatever you wanted at the other, using something called molecular-beam epitaxy to spray atoms and molecules directly onto a substrate. Greenberg didn’t understand any of these new gadgets, even the stuff you could see.

It was strange for Greenberg to remember now how much agonizing there had been when he was growing up about the depletion of Earth’s resources, the need to close the loops of mass and energy, as if Earth itself was one big CELSS. Nobody worried about that any more; the solar system had worked out to be just too rich in resources; those loops would stay open for a long time yet.

It took a long time for the economics and demographics and such to work out, but it had all been pretty much inevitable, it seemed to Greenberg. It was just so much cheaper to send resources skimming between the rocks than to haul them out of the planets’ big gravity wells. The colonies on Mars and the Moon had shrivelled and died, and Earth – growing poorer, its population steadily declining – had turned into a kind of huge theme park: a museum of the human species, but studded with pits of abject poverty, in the darkened ruins of the old cities. Nobody knew what was happening in those pits.

And nobody much cared, because beyond old Earth there were too many people even to count.

If you knew where to look, the sky was full of inhabited rocks, with their little orbital necklaces of solar power stations, and habitats studding their surfaces or buried inside, green and blue, the old colours of life. It was estimated that for every person alive when Greenberg was born, there were a billion human souls now. That was a hell of a thought. And when he considered some of the assholes he used to have to work with back in those days, a dismaying one.

In Ra there was a whole bunch of little Weissmans, though not all of them used Mike’s old name any more, and so in his head Greenberg thought of them all as Weissmans; it made it easier to love them. Mike would have been pleased, anyhow. There were no Greenbergs, though. His line had finished with a great-grandchild, a male, who had got caught up in the New AIDS epidemic of the twenty-second century, and died childless. It was ironic. Here was Greenberg, perhaps the oldest surviving human, and not one of all those teeming trillions floating around the system could claim direct descent from him.

On the other hand, by the laws of statistics, there ought to be a billion Einsteins out there. Nobody knew what they were all doing. They sure weren’t working together.

All those pious dreams of the space buffs of some kind of giant solar-system civilization had never been remotely likely. There were just too many people. The human race had gathered into a billion small-town-sized tribes and splintered, shaping and seeking goals unimaginable to an Earth-born geezer like him.

It seemed to him, in fact, that he was watching the end of the species, as a unitary whole: two million years out of Africa, the race had escaped from the cradle and was growing, to where the hell nobody could even guess.

… And now here came Toutatis on its aerobraking pass.

The rock looked like a comet glowing in the thin upper air of Earth, streaking by in a perfect straight line below Greenberg. It made the cities and oceans of Earth glow like the day – it must have been a remarkable sight from down there – and asteroid light played on his own face, the ancient bones of his eye sockets.

The encounter was over in seconds. The trail of scorched air soon dissipated and dimmed, and Toutatis, its orbit subtly altered, passed on towards its next encounter. It was going to take fifty years to nudge Toutatis into its final low Earth orbit, but planning projects on that kind of time scale didn’t seem to trouble the inhabitants of Toutatis, or anybody else.

The show was over. The people of Ra-Shalom drifted away from their blue watery windows, and returned to their mysterious business within.

Greenberg had never meant to live for a thousand years. It was ridiculous. Nobody else had stuck around like this. It was just that he would have had to have chosen when to die, and that was something he had never expected to face when he grew up, and he just had no instinct for it.

Anyhow, if he let himself die, he would have missed this.

Greenberg, with a sigh, turned away from the window and went to his instrument consoles.

It was a massive asteroid, big enough to have dragged itself into a sphere, with planet-like layers of internal structure, rich in metals, rocks and volatiles. It was bathed by the light of a sun only three times as far away as from Earth.

The guardians considered carefully. It was, after all, to be the repository of all that was left of their designers’ species, until even this new young sun guttered and died.

They were machines designed to plan for billions of years. They had already nursed their fragile cargo across such deserts of time. Now, looking to the future, they must plan for evolution, even the loss of mind.

It was a good home, rich in energy and resources.

The guardians were satisfied. They closed themselves down.

Within the rock, history continued.