Firstborn

you to the floor. So the design emulated space stations with hand-and footholds, Velcro pads, and a color coding with brown beneath and blue above, so that you could always know at a glance which way up you were.

But on the other hand that one percent of G was steady and unrelenting. Experimenting, Bisesa found that if she clambered up to the ceiling and let go, she would drift down to the floor in six or seven seconds, falling like a snowflake and settling softly. That little bit of gravity was surprisingly useful, for it induced dust to settle and any disturbed clutter to fall eventually out of the air; here she would not have to wrestle with rogue blankets, or track down stray droplets shimmering away from her coffee cup.

The “bridge” of the Maxwell was set out pretty informally with chairs and tables. Bisesa was reminded that this wasn’t a military ship. When Bisesa and Myra came drifting up the short ladder from the lower deck Alexei was sitting in one of those chairs, patiently watching displays unfold across a softscreen.

The walls were utterly transparent.

Space was starless, empty save for three lamps, sun, Earth, and Moon, which hung in a tremendous triangle around the ship.

Something in Bisesa quailed before this array of worlds. For some reason she thought of Mir and the man- apes she had seen there, australopithecines with the legs of humans and the shoulders of gorillas.

Myra saw her reaction and tugged her hand. “Mum. It’s just another fairground ride. Never mind feeling dizzy. Look up. ”

Bisesa lifted her head.

She saw a disk of not-quite-darkness, a little grayer than the deep velvet of the sky. Highlights, sun-dazzling bright, rippled across its face. It was the sail, a sheet of foil big enough to have wrapped up the whole of inner London. She could hear gentle, intermittent whirs that must be the tiny pulleys fixed around the roof, tugging at the rigging that ran up and out from the roof above her, rectilinear threads that caught the sunlight.

The hull that enclosed her was a tuna can hanging under a parachute.

“Welcome aboard the James Clerk Maxwell, ” Alexei said, grinning.

“All this from sunlight.”

“Yes.” Alexei held up his hand in a shaft of sunlight that crossed the cabin. “The pressure of all those tiny photons, pinging off a reflecting surface. On your face on a sunny day on Earth, that force amounts to only maybe one ten-thousandth of a gram. We have enough sail area, and a low enough mass, for an acceleration of a hundredth of a G. But it’s continuous, and free, and it just keeps on pushing and pushing… Which is how we can reach Mars in twenty days.”

The sail itself was based on a mesh of nanotube string, the same super-strong stuff they made the space elevator ribbons from. The

“fabric” was an ultra-thin film of boron, only a few hundred atomic diameters thick. It had to be sprayed on.

“The sail fabric is so fine that if you handle it it’s more like smoke than anything substantial,” Alexei said. “But it’s robust enough to be able to stand a dip into the sun’s heat inside the orbit of Mercury.”

Ribs of light washed across the face of the mirror; tiny pulleys whirred.

“You get these oscillations all the time,” Alexei said. “That’s why we make the sails smart, as the sun shield was. The fabric is embedded with actuators and tiny rocket motors. Max, the ship’s AI, can keep himself positioned correctly. And he does most of the navigation; I just tell him where I want to go. Max is in charge, really. Thank Sol he doesn’t brag about it too much.”

Bisesa said, “I can see how you can be pushed away from the sun. But how can you sail inward— from Mars in toward Earth, say? I guess it’s sort of like tacking into the wind.”

“It’s not a good analogy,” Alexei said evenly. “You have to remember that all objects in the solar system are essentially in orbit around the sun. And that determines how the sail functions…”

Orbital mechanics could be counter to common sense. “If I speed up, I raise my orbit. But if I fix my sail so that the sunlight pressure opposes my motion, my orbital velocity falls, and I will spiral in toward the sun…” Bisesa studied the diagrams he produced on the softscreens, but when he started scrolling equations she gave up.

“This is all intuitively obvious to you, isn’t it? The principles of celestial mechanics.”

He waved a hand at the worlds around them. “You can see why.

Up here you can see those laws working out. I’ve often wondered how Earthbound scientists were able to make any sense out of all the clutter down there. The first lunar astronauts, a hundred years ago, the first to come out this way, came back changed, for better or worse.

A lot of us Spacers are deists, or theists, or pantheists — somewhere on that spectrum.”

“Believing that God is to be found in physical laws,” Myra said.

“Or God is those laws.”

“I suppose it makes sense,” Bisesa said. “Religions and gods don’t have to go together. Buddhists don’t necessarily believe in a supreme being; you can have religion independent of any god.”

Myra nodded. “And we can believe in the Firstborn without having any religion at all.”

Alexei said mildly, “Oh, the Firstborn aren’t gods. As they will learn one day.”

Bisesa said, “But you aren’t a theist. Are you, Alexei? You like to quote the Bible, but I’ve heard you pray —Thank Sol?”

He looked sheepish. “You got me.” He lifted his face to the sunlight. “Some of us have a sneaking regard for the Big Guy. The engine that keeps us all alive, the one object you can see however far you roam across the system.”

Myra nodded. “I heard of this. A cult of Sol Invictus. One of the last great pagan gods — from the Roman empire, just before they proclaimed Christianity their official cult. Didn’t it sprout on Earth again, just before the sunstorm?”

Alexei nodded. “There was a lot of propitiation of angry gods to be done in those days. But Sol Invictus was the one that took hold with the early Spacers, especially those who had worked on the shield. And he spread.”

Bisesa remembered another sun god who had interfered in her own life: Marduk, forgotten god of Babylon. She said, “You Spacers really aren’t like the rest of us, are you, Alexei?”

“Of course not. How could we be?”

“And is that why you’re taking me to Mars? Because of a different perspective?”

“More than that. Because the guys down there have found something. Something the Earth governments would never even have dreamed of looking for. Although the governments are looking for you, Bisesa.”

Bisesa frowned. “How do you know?”

Alexei looked uncomfortable. “My father is working with the World Space Council. He’s a cosmologist…”

So there it was, Bisesa thought, this new generational gap set out as starkly as it could be. A Spacer son spying on his Earthbound father.

But even though they were in deep space he would say no more about where Bisesa was being taken, and what was expected of her.

Myra pulled her lip. “It’s odd. Sol Invictus — he’s such a contrast to the cool thinking of the theists.”

“Yeah. But don’t you think that until we get these Firstborn assholes beaten, we need an Iron Age god?” And Alexei grinned, showing his teeth, a shockingly primate expression bathed in the light of sun and Moon.

Bisesa, worn out by stress and strangeness, retreated to her newly constructed cabin. She rearranged her few possessions and strapped herself to the narrow bunk.

The partitioned-off room was small, but that didn’t bother her.

She had been in the army. As accommodations went, this was a lot better than the UN camp in Afghanistan where she had been stationed before falling into Mir.

It struck her that this living deck seemed cramped, though, even given the basic geometry of the tuna-can hull. She thought back to her inspection of the utility deck earlier; she had a good memory for spaces and volumes. Sleepy, she murmured aloud, “So why is this deck so much smaller than the utility level?”

A soft voice spoke. “Because these walls are full of water, Bisesa.”

“Is that you, Thales?”