She pulled herself tentatively along the slide wire, and made her way to the PMU station, on the starboard side of the hab module. The Personal Manoeuvring Unit was a big backpack shaped like the back and arms of an armchair, with foldout head- and leg-rests on a tubular frame. Nadezhda ran a quick check of the PMU’s systems.

Then she turned around, and backed into the PMU.

“Sagan, Nadezhda,” she said. “Suit latches closed.”

Copy that.

She pulled the PMU’s arms out around her and closed her gloved hands around the hand-controllers on the end of the arms. She unlatched the folded-up body frame. She rested her neck against the big padded rest, and settled her feet against the narrow footpads at the bottom of the frame, so she was braced. Today’s EVA was just a test reconnaissance, but a full field expedition to Icarus could last all of eight hours; the frame would help her keep her muscle movements down, and so reduce resource wastage.

Nadezhda released her tethers. A little spring-loaded gadget gave her a shove in the back, gentle as a mother’s encouraging pat, and she floated away from the bulkhead.

…Suddenly she didn’t have hold of anything, and she was falling.

She had become an independent spacecraft. The spidery frame of the PMU occulted the dusting of stars around her.

She tested out her propulsion systems.

She grasped her right-hand controller, and pushed it left. There was a soft tone in her helmet as the thruster worked; she saw a faint sparkle of exhaust crystals, to her right. In response to the thrust, she tipped a little to the left.

When she started moving, she just kept on going, until she stopped herself with another blip of her thrusters.

She turned in space, and looked at the Moon. She pressed a stud on the side of her helmet, and the Moon’s image was magnified, so that its crescent filled her helmet. And the crescent’s edge was softly blurred by a band of light, which stretched part way around the darkened hemisphere.

Sparks crawled over the globe: ocean-going vessels, surface cars, low-orbit spacecraft. There were more lights, strung out in lines, on the darkened surface itself: towns and cities, outlining hidden continents. Buildings on the Moon were mostly made entirely of glass; lunar glass, manufactured from deep-lying dehydrated lunar ore, was incredibly strong. From space, all that glass made the cities bright.

But the sun-shadowed hemisphere was not truly dark, for it basked in the light of the Noviy Svet — the Russian-designed solettas, the huge mirror farms built and launched by Boeing and Kawasaki Heavy Industries, artificial suns which cast enough daylight over the shadowed half of the Moon to keep its new air from snowing out in the weeks-long night. The solettas worked well, and anyhow the engineers said the Spin-Up should be completed before the solettas reached the end of their design life.

Not that anybody was confident of predicting when that would be, since the solettas, grown from lunar rock, were the first large-scale application of Moonseed-derived technology.

She could see the cold deserts of the lunar poles, bone-white.

On the Moon, the weather was simple. Sunlight lifted masses of moist warm air over the equator; the air quickly dumped its moisture, in sometimes violent rainstorms, and, displaced by colder, lower layers of air, the hot air drifted to the poles. There it cooled and sank, dry and cold, creating deserts, and joined the circulation back to the equator.

So there you had it. The prevailing winds were hot, dry air coming out of the poles, deflected a little by the Moon’s sluggish spin, shaped and moistened by the bodies of water it passed, the maria and the great crater lakes.

On the Moon, there were no weather forecasters.

She couldn’t remember much of Earth, before the Bottleneck. She found it hard to understand how big it had been, so big there had been room for more than one air circulation cell per hemisphere, so big there had been room for too much weather. Bizarre.

Anyhow, the Moon’s North Pole was the site of something much more interesting than weather, as far as Nadezhda was concerned. It was from the Pole that the great deep-core drilling project had been initiated by the Americans: a thousand-mile shaft designed to reach all the way to the Witch in the Well, the ancient, shattered hive at the heart of the Moon which, until now, had only been visible by seismic probes and neutrino light. And nobody knew what treasures that would bring.

The Moon’s highlands and Farside were visibly peppered with circular crater lakes, glimmering in soletta light. The first oceans, which had pooled in the basins of the old maria, still glittered blue where they had formed, all over the hemisphere which was still called Nearside; but they had been shrinking steadily since then. The problem was drainage. The oceans evaporated, the water returning as rain; but every time rain fell on the highlands it got trapped in the high craters. As the Moon had been born dry, there was no natural drainage to return the water to the oceans, as on Earth.

So great channels were being dug, canals to restore the water to the oceans. Nadezhda could see Tycho-Nubium, for instance, a straight-line thread of blue light.

Thus, on the Moon, by the side of the canals with their huge waves and feathery pleasure-boats, the crystal cities glistened in the sun.

As she looked at the Moon’s surface now, it was predominantly blue and white, ocean and cloud, or the powder-grey or baked red of desert. Much of the Moon was still not much more habitable than it had been for Meacher and Bourne themselves. It would take some time for the green of life to show on the Moon.

It would come.

But the Moon would never be a shrunken twin of vanished Earth. The engineers” dreams would see to that. They could do a lot better.

There was a scheme to go further than Spin-Up. Perhaps the black hole wind from ruined Earth could be used to move the Moon: to the orbit of Jupiter, perhaps, where there were whole worlds full of frozen volatiles, waiting to be tapped…

Or even further, to the stars themselves.

But that was the future. For today, Nadezhda had work to do.

Nadezhda tipped herself up so she was facing Icarus, with the Sagan behind her.

“Sagan, I’m preparing to go in.”

We copy, Nadezhda.

She fired her thruster. Computer graphics started to scroll across the inside of her face plate, updating burn parameters. She was actually changing orbit here, and she would have to go through a full rendezvous procedure to reach Icarus.

The angle of the sun was changing, and the slanting light changed Icarus from a flat silhouette to a potato-shaped rock in space, fat and solid. Icarus was crumpled, split by ravines, punctured by craters of all sizes, the beat-up surface a record of this little body’s dismal, violent history. There was one massive crater that must have been a half-mile across, its walls spreading around the cramped horizon.

The rock was more than three miles long, spinning on its axis once every twenty hours. It was as black as coal dust. Icarus was a stony asteroid, its substance baked dry of water and other volatiles by a billion years of passes around the sun, here in the hot heart of the Solar System.

Primordial rock. Ideal resource for the Moonseed.

It was a decade now since Icarus had been deliberately implanted with Moonseed, by an automated probe. The purpose was to test experimental asimov circuits, to see if the Moonseed could be inhibited.

Well, since the asteroid hadn’t blown up, the asimov circuits seemed to have worked. And now, Nadezhda was here to find out what the Moonseed had built, at the heart of the asteroid. We know you can make solar sails. We know you can turn planets into black hole guns. Now let’s see what the hell else you can do…