Space

sphere, perfectly reflective, it should have been as bright as the Sun.”

“Like Mirror.”

“Yes. So Leonardo argued the Moon must be covered in oceans.” He found a diagram showing a Moon coated with great out-of-scale choppy waves and bathed in spidery sunlight rays. “Leonardo said waves on the Moon’s oceans must deflect much of the reflected sunlight away from Earth. He thought the darker patches visible on the surface must mark great standing waves, or even storms, on the Moon.”

“He was wrong,” she said. “In Leonardo’s time, the Moon was a ball of rock. The dark areas were just lava sheets.”

“Yes, of course. But now,” Berge said eagerly, “the Moon is mostly covered by water. You see? And there are great storms, wave crests hundreds of kilometers long, that are visible from Earth — or would be, if anybody was left to see…”

They talked for hours.

When he left, she went to the door to wave him good-bye.

The Day was little advanced, the rake of sunlight still sparse on the ice, and Mirror still rode bright in the sky. Here was another strange forward echo of Leonardo’s, it struck her, though she preferred not to mention it to her already overexcited grandson: in these remote times, there were crystal spheres in orbit around the Earth. The difference was, people had put them there.

As she closed the door she heard the honking of geese, a great flock of them fleeing the excessive brightness of full Daylight.

Each Morning, as the Sun labored into the sky, there were storms. Thick fat clouds raced across the sky, and water gushed down, carving new rivulets and craters in the ancient soil and turning the ice at the rim of the Tycho pack into a thin, fragile layer of gray slush.

The storms persisted as Noon approached on that last Day, and she traveled with Berge to the phytomine celebration to be held on the lower slopes of Maginus.

They made their way past sprawling fields tilled by human and animal muscle, thin crops straining toward the sky, frost shelters laid open to the muggy heat. And as they traveled they joined streams of battered carts, all heading for Maginus. Xenia felt depressed by the people around her: the spindly adults, their hollow-eyed children — even the cattle and horses and mules were skinny and wheezing. The Moon soil was thin, and the people and animals were all, of course, slowly being poisoned besides.

Most people chose to shelter from the rain. But to Xenia it was a pleasure. Raindrops here were fat glimmering spheres the size of her thumb. They floated from the sky, gently flattened by the resistance of the thick air, and they fell on her head and back with soft, almost caressing impacts, and water clung to her flesh in great sheets and globes she must scrape off with her fingers. So long and slow had been their fall from the high clouds that the drops were often warm, and the air thick and humid and muggy. She liked to think of herself standing in the band of storms that circled the whole of the slow-turning Moon.

It reminded her of the day of Frank Paulis’s final triumph.

She remembered that first hour when it was possible to step outside the domes — the first hour when unprotected people could survive on the Moon, swathed as it was by air drawn up by the great mines that bore Paulis’s name — an hour that had come to pass thanks to Frank’s ingenuity, courage, determination, and downright unscrupulous dishonesty. Frank, doggedly, had lived to see it, and on that day the authorities let him out of house arrest, just briefly. They wouldn’t permit him to be the first to walk out of a dome without a mask — they couldn’t bring themselves to be as generous as that. But he was among the first. And that was, perhaps, enough. She remembered how he had stalked in the fresh air, squat and defiant, sniffing up great lungfuls of the air he had made, and how he had laughed as the rain trickled into his toothless mouth, fat lunar drops of it.

And, soon after that, he had died.

After that Xenia had left, with the Gaijin, for the stars.

When she returned home she found that thirteen hundred years of history had worn away, leaving the Earth a cloud-covered ruin, the Solar System threatened by interstellar war, the last humans struggling to survive on Mercury and the Moon. Nobody remembered her, or much of the past: It was as if this attenuated, unstable present was all there ever had been, all that would ever be. So she had shed her old identity, settled into the community here.

Thanks to her engineered biology, a gift of the futures she had visited, she had remained young, physically. Young enough to bear children, even. But now, despite the invisible engineering in her flesh, she was slowly dying, as was everybody, as was the Moon.

How strange that the inhabited Moon’s life had been as brief as her own: that her birth and death would span this small world’s, that its rocky bones would soon emerge through its skin of air and ocean, just as hers would push through her decaying flesh.

At last they approached Maginus.

Maginus was an old, eroded crater complex to the southeast of Tycho. Its ancient walls glimmered with crescent lakes and glaciers. Sheltered from the winds of Morning and Evening, Maginus was a center of life, and long before they reached the foothills, as the fat rain cleared, she saw the tops of giant trees looming over the horizon. She thought she saw creatures leaping between the tree branches. They may have been lemurs, or even bats; or perhaps they were kites wielded by ambitious children.

Berge showed delight as they crossed the many water courses, pointing out engineering features that had been anticipated by Leonardo: dams and bridges and canal diversions and so forth, some of them even constructed since the Failing. But Xenia took little comfort, oppressed as she was by the evidence of the fall of mankind. For example, they journeyed along a road made of lunar glass, flat as ice and utterly impervious to erosion, carved long ago into the regolith by vast space-borne engines. But they traveled this marvelously engineered highway in a cart that was wooden, and drawn by a spavined, thin-legged mule.

Such contrasts were unendingly startling to a time-stranded traveler like Xenia. But, she thought with a grisly irony, all the technology around them would have been more than familiar to Berge’s hero, Leonardo. There were gadgets of levers and pulleys and gears, their wooden teeth constantly stripped; there were turnbuckles, devices to help erect cathedrals of Moon concrete; there had even been pathetic lunar wars fought with catapults and crossbows, “artillery” capable of throwing lumps of rock a few kilometers.

But once people had dug mines that reached the heart of the Moon. The people today knew this was so, else they could not exist here. She knew it was true, for she remembered it.

As they neared the phytomine, the streams of traffic converged to a great confluence of people and animals. There was a swarm of reunions of friends and family, and a rich human noise carried on the thick air.

When the crowds grew too dense, Xenia and Berge abandoned their wagon and walked. Berge, with unconscious generosity, supported her with a hand clasped about her arm, guiding her through this human maelstrom.

Children darted around her feet, so fast she found it impossible to believe she could ever have been so young, so rapid, so compact, and she felt a mask of old- woman irritability settle on her. But many of the children were, at age seven or eight or nine, already taller than she was, girls with languid eyes and the delicate posture of giraffes. The one constant of human evolution on the Moon was how the children stretched out, ever more languorous, in the gentle gravity. But in later life they paid a heavy price in brittle, calcium-starved bones.

All Berge wanted to talk about was Leonardo da Vinci.

“Leonardo was trying to figure out the cycles of the Earth. For instance, how water could be restored to the mountaintops. Listen to this.” He fumbled, one-handed, with his dog-eared manuscript. “ ‘We may say that the Earth has a spirit of growth, and that its flesh is the soil; its bones are the successive strata of the rocks which form the mountains; its cartilage is the tufa stone; its blood the veins of its waters… And the vital heat of the world is fire which is spread throughout the Earth; and the dwelling place of the spirit of growth is in the fires, which in divers parts of the Earth are breathed out in baths and sulphur mines…’ You understand what he’s saying? He was trying to explain the Earth’s cycles by analogy with the systems of the human body.”

“He was wrong.”

“But he was more right than wrong, Grandmother! Don’t you see? This was centuries before geology was formalized, before matter and energy cycles would be understood. Leonardo had gotten the right idea, from somewhere. He just didn’t have the intellectual infrastructure to express it…”

And so on. None of it was of much interest to Xenia. As they walked it seemed to her that his weight was the heavier, as if she, the foolish old woman, was constrained to support him, the young buck. It was evident his sickliness was advancing fast — and it seemed that others around them noticed it too, and separated around them, a sea of unwilling sympathy.

At last they reached the plantation itself. They had to join queues, more or less orderly. There was noise, chatter, a sense of excitement. For many people, such visits were the peak of each slow lunar Day.

Separated from the people by a row of wooden stakes and a few meters of bare soil was a sea of growing green. The vegetation was predominantly mustard plants. Chosen for their bulk and fast growth, all of these plants had grown from seed or shoots since the last lunar Dawn. The plants themselves grew thick, their feathery leaves bright. But many of the leaves were sickly, already yellowing.

The fence was supervised by an unsmiling attendant, who wore — to show the people their sacrifice had a genuine goal — artifacts of unimaginable value: earrings and brooches and bracelets of pure copper and nickel and bronze.

The attendant told them, in a sullen prepared speech, that the Maginus mine was the most famous and exotic of all the phytomines: for here gold itself was mined, still the most compelling of all metals. These mustard plants grew in soil in which gold, dissolved out of the base rock by ammonium thiocyanate, could be found at a concentration of four parts per million. But when the plants were harvested and burned, their ash contained four hundred parts per million of gold, drawn out of the soil by the plants during their brief lives.

The phytomines, where metals were slowly concentrated by living things, were perhaps the Moon’s most important remaining industry.

As Frank Paulis had understood centuries ago, lunar soil was sparse and ungenerous. And yet, now that Earth was wrecked, now that the spaceships no longer called, the Moon was all the people had.

The people of the Moon had neither the means nor the will to rip up the top hundred meters of their world to find the precious metals they needed. Drained of strength and tools, they had to be more subtle.

Hence the phytomines.

The technology was old — older than the human Moon, older than spaceflight itself. The Vikings, marauders of Earth’s dark age, would mine their iron from “bog ore,” iron-rich stony nodules deposited near the surface of bogs by bacteria that had flourished there: miniature miners, not even visible to the Vikings, who burned their little corpses to make their nails and swords and pans and cauldrons.

And so it went, across this battered, parched little planet, a hierarchy of bacteria and plants and insects and animals and birds collecting gold and silver and nickel and copper and bronze, their evanescent bodies comprising a slow, merging trickle of scattered molecules stored in leaves and flesh and bones, all for the benefit of that future generation who must someday save the Moon.

Berge and Xenia, solemnly, took ritual scraps of mustard-plant leaf on their tongues, swallowed ceremonially. With her age-furred tongue she could barely taste the mustard’s sharpness. There were no drawn-back frost covers here because these poor mustard plants would not survive to the Sunset: They died within a lunar Day, from poisoning by the cyanide.

Berge met friends and melted into the crowds.

Xenia returned home alone, brooding.

She found that her family of seals had lumbered out of the ocean and onto the shore. These were constant visitors. During the warmth of Noon they would bask for hours, males and females and children draped over each other in casual abandon, so long that the patch of regolith they inhabited became sodden and stinking with their droppings. The seals, uniquely among the creatures