Death's End

“The Staircase Program needs to send someone who knows Yun Tianming to the future.”

Cheng Xin stopped.

“However, that person must be a member of the PIA and under my command. Are you interested? Or do you want to hand in your resignation now?”

Cheng Xin continued walking, but her stride slowed down. Finally, she stopped a second time. Wade’s voice came again. “You’d better be sure about your choice this time.”

“I agree to go to the future,” Cheng Xin said. She leaned against the doorframe for support. She didn’t turn around.

—————

The only time Cheng Xin got to see the Staircase spacecraft was when its radiation sail unfolded in orbit. The giant sail, twenty-five square kilometers in area, briefly reflected sunlight onto the Earth. Cheng Xin was already in Shanghai, and she saw an orange-red glowing spot appear in the pitch-black sky, gradually fading. Five minutes later, it was gone, like an eye that materialized out of nowhere to look at the Earth and then slowly shut its eyelid. The craft’s journey as it accelerated out of the Solar System was not visible to the naked eye.

Cheng Xin was comforted by the fact that the seeds did accompany Tianming—not her seeds, exactly, but seeds that had been carefully selected by the space agricultural department.

The giant sail’s mass was 9.3 kilograms. Four five-hundred-kilometer cables connected it to the space capsule, whose diameter was only forty-five centimeters. A layer of ablative material covered the capsule, making its launch mass 850 grams. After the acceleration leg, the capsule mass would be reduced to 510 grams.

The acceleration leg stretched from the Earth to the orbit of Jupiter. A total of 1,004 nuclear bombs were distributed along the route, two-thirds of which were fission bombs, the rest fusion. They were like a row of mines that the Staircase craft triggered as it passed by. Numerous probes were also distributed along the route to monitor the craft’s heading and speed and coordinate minute adjustments to the positions of the remaining bombs. Like the pulses of a heart, successive nuclear detonations lit up the space behind the sail with blinding glows, and a storm of radiation propelled this feather forward. By the time the spacecraft approached Jupiter’s orbit and the 997th nuclear bomb exploded, monitoring probes showed that it had achieved 1 percent of lightspeed.

That was when the accident occurred. Analysis of the frequency spectrum of the light reflected from the radiation sail showed that the sail had begun to curl, possibly because one of the towing cables had broken. However, the 998th nuclear bomb detonated before adjustments could be made, and the craft deviated from the projected course. As the sail continued to curl, its radar profile rapidly shrank, and it disappeared from the monitoring system. Without precise parameters for its trajectory, it would never be found again.

As time passed, the spacecraft’s trajectory would deviate farther and farther from the projection. Hopes that it would intercept the Trisolaran Fleet diminished. Based on its approximate final heading, it should pass by another star in six thousand years and depart the Milky Way in five million years.

At least the Staircase Program was a half success. For the first time, a man-made object had been accelerated to quasi-relativistic speeds.

There was no real reason to send Cheng Xin to the future anymore, but the PIA still asked her to enter suspended animation. Her mission now was to act as a liaison to the Staircase Program in the future. If this pioneering effort was to be helpful to humanity’s spaceflight efforts in two centuries, someone who understood it deeply had to be there to explain the dead data and interpret the mute documents. Of course, perhaps the real reason for sending her was only one of vanity, a wish that the Staircase Program would not be forgotten by the future. Other large contemporary engineering projects had made similar efforts to send liaisons to the future for similar reasons.

If the future wished to pass judgment on our struggles, then at least it was now possible to send someone to the future to explain the misunderstandings brought about by the passage of time.

As Cheng Xin’s consciousness faded in the cold, she held on to a ray of comfort: Like Tianming, she would drift through an endless abyss for centuries.

PART II

Deterrence Era, Year 12 Bronze Age

It was now possible to see the Earth with the naked eye from the view window of Bronze Age. As the ship decelerated, those who weren’t on duty came to the open space at the stern to observe the Earth through the wide portholes.