Jiang said, “What does the Nullist phenomenon say about the world we are constructing for the young, Barbara?”

Fahy looked out, at bustling Shenzhen. “Perhaps that it is hell indeed,” she said. She looked up; the Moon was rising, its face — still bearing American footprints — battered and lifeless. “And there is no escape.”

The two of them left the tea shop and walked back towards the hotel.

In the distance, a couple of blocks away, she saw some kind of disturbance. A pack of children were attacking a sack of what looked like food — tangerine fruit, maybe. They attacked the pack like animals, she thought; their hunger was not feigned. Adults were joining in, beating at the children with sticks. She caught a glimpse of running police, the distant crackle of gunfire.

Day 169

Siobhan Libet pulled herself out of the hab module, and she crawled through the flexible access tunnel into the farm.

The CELSS farm — CELSS, for closed environment life support system — was a basic pressurized cylinder sixteen feet long and fourteen across, fitting neatly into Discovery’s payload bay. It had been improvised from a couple of old Spacelab modules. Spacelab was the pressurized workshop provided by the Europeans for flying aboard Shuttle. Now that Spacelab wasn’t going to fly any more, the redundant hardware had been turned to better use.

As she closed the hatch behind her, Libet felt an immediate sense of cosiness, of warmth, of brightness. The pressure was high in here. The glow of the banks of lights was warm on her face, and the air seemed thick and humid and full of the smell of chlorophyll, of growing things; it was, simply, like being inside a compact greenhouse.

The equipment racks and data processing consoles of the old low-Earth-orbit experimenters had been stripped out, and replaced by three racks of plants. The racks were thick, with fat pipes carrying nutrient solution that flowed beneath them. Fluorescent tubes were poised above each of the racks, flooding the place with a cool white light, and bundles of fiber-optic cables brought light to the darker corners of the farm. The racks were immersed in pipes and cabling and sensors, and there was a constant hiss of fans and extractors, a warm gurgling of fluids through the pipes. There was a gap down the center of the racks, just big enough to admit a human to work.

Looking into the farm racks was a little like looking into a huge refrigerator, the green of the growing plants somehow dulled and coarsened by the flat white light of the tubes. As technology, the whole thing always looked strangely primitive to Libet.

But it was working, after a fashion. Plants, green and spindly, strained upwards towards the lights, from the plastic surfaces of the racks. This was a salad machine, in the jargon, the best-studied form of closed life support system; the other choices had been a yoghurt box — algae — and a sushi maker, a fish farm.

There was a locker close to the hatch. When Libet opened it, the usual jack-in-the-box effect shoved out a lightweight coverall, gloves, a hat and a small toolkit. She pulled on the coverall and hat, and donned the gloves. Humming, she prepared to work.

It was actually Bill Angel who noticed the SPE problem first.

Inside the hab module he was working — in conjunction with the ground — through a check of Discovery’s navigation systems; and, as usual, he was royally pissed off.

He was finding life in Discovery a lot more irritating and frustrating than he’d expected. His uppermost beef today was that nothing ever seemed to be stowed in the right place. There was supposed to be a computer tracking system, at JSC, that would keep track of every item on the ship, but that had soon broken down when his asshole crewmates insisted on not putting stuff back where it belonged. As a result he spent half his precious time raking through drawers and lockers, and every time he opened a drawer all the crap would come spilling out all over the place and he’d have to hunt it down and ram it back…

Ah, the hell with it. At least the work he was doing today had some intellectual meat to it.

But he was having problems with the navigation systems.

The point of navigation, and the mid-course burns called trajectory correction maneuvers — TCMs — was to keep the spacecraft on its planned trajectory for the duration of the flight. For six years, Discovery was going to coast, mostly unpowered, all the way to its rendezvous with Saturn. The way Angel thought of TCMs, it was like cheating at pool. It would be much easier to sink a long shot if, after the ball had been struck, you were allowed to nudge the ball a couple of extra times with the cue stick as the ball headed towards the pocket. Well, that was the idea of the TCMs; without those small adjustments the spacecraft would miss Saturn by many millions of miles.

But it all depended on precise navigation.

There were actually three navigation techniques in use on Discovery: doppler, ranging, and optical navigation. The first two could be run from Earth. Doppler was a way to measure the speed the ship was approaching or receding from the Earth, and ranging exploited the finite speed of light to measure the distance from the spacecraft to the Earth. When used together, Discovery’s position and speed could be determined very accurately…

But not accurately enough, over the billion miles Discovery was to travel. The only way was to navigate from the spacecraft itself, by the stars.

There was a kit of hand-held gear, a sextant and low-power optical telescope, and there were camera systems. The most basic systems — and the most heavily used — were the simple light-sensing star trackers that had been installed around Discovery, in the wings and boattail and nose. Without intervention from the crew these could fix on the sun and Earth and maybe a fixed star, like Canopus, allowing Discovery to triangulate its position.

But today something was wrong; the star trackers kept losing their locks.

Angel — ill-tempered, impatient — probed at the problem. The trackers seemed to be picking up a lot of false images, whole constellations of them, that made it impossible for them to recognize their stellar targets. That wasn’t so unusual in itself — the spacecraft was habitually surrounded by floating chunks of debris, flecks of paint or insulation that had broken away, all of which glittered like stars in the intense sunlight — but it was unusual for such a flood of false readings to hit all the trackers, all at once. Maybe something had come loose in the cargo bay, he thought.

Then the word came up from the ground.

“Discovery,Houston…” They didn’t wait out the time delay for his reply. “We’ve been looking at your anomalous tracker readings. We figure that what they’re seeing is Cherenkov radiation. Repeat, Cherenkov…”

Oh.

Angel knew the implications.

When a high-energy subatomic particle hit a star tracker, it could rip through the tracker’s glass window faster than the speed of light in the glass. There would be a kind of optic boom — a blue flash, a burst of Cherenkov radiation, a spark confusing the sensors.

Cherenkov radiation meant that from some source, heavy, fast-moving particles were scouring through Discovery.

Angel acknowledged the message, and asked for a confirmation.

Most of the plants were growing hydroponically, with their roots bathed in a liquid nutrient solution called Salisbury/Bugbee. As a backup, others were growing in an experimental soil substitute based on zeolite granules impregnated with potassium and nitrogen and other nutrients, like little time-release pills, with enough nutrients to last years.