Rebirth: Starting from Lighting Up the Tech Tree

four years ago.

Pioneer has been away from Earth for more than four years.

The 137-meter-long hull is covered with traces of micrometeorite impacts, and the heat-resistant coating on the bow has been worn away by interstellar dust, revealing silver titanium alloy.

Shen Yiming sent back his last travel log, number 1102. It contained only one line: "I saw the moon. I also saw home. Expected to enter orbit in thirty-seven days."

Ground received. Welcome home.

Thirty-seven days later, Pioneer completed its final engine shutdown in low Earth orbit.

The four-year expedition has ended. The six crew members were brought back to Earth by a docking ship from Deep Space 402. The docking ship landed on the runway of Deep Space 402.

When the cabin door opened, it was drizzling in Hangzhou.

His feet, which hadn't stepped into rain for six years, touched the wet ground. Ji Beihang was the first to step out, stood for three seconds, and took a deep breath.

He said: Air has a smell. The air in deep space has no smell.

Shen Yiming was the last to come out. He looked up at the sky. It was hazy and he couldn't see anything. But he said, "There are stars above the clouds."

I'm sure. The first thing they did on the ground wasn't hugging families or holding a press conference. It was going together to the first office 402 was founded in, that small room in the incubator. The room was smaller than I remembered.

Shen Yiming walked to the whiteboard where the five of them had taken a group photo ten years ago. The writing was long faded, but one line was still legible: "We're going to do something different." He added a line below it with a marker: Done. Now, let's do something even more different.

Ji Beihang laid a neatly folded interstellar civilization flag on the table. Three small holes had been punched in the four corners of the flag by micrometeorites.

He said: This flag flew about ten billion kilometers. Enough to circle the Earth two thousand five hundred times. Now it's home.

Tan Yue stood at the doorway, gazing at the room for a long time. He said, "When I was writing in my journal, I always thought about what the first thing I would do if I came back someday. But now that I'm actually back, I don't want to do anything. I just want to stand here and look around."

Wenya placed her medical kit on the floor and sat down against the wall. Four years in deep space had reduced her bone density by six percent and her muscle mass by eleven percent. But she smiled and said, "The first thing I'll check up on when I get back is my hand. It's still there. I can still have surgery."

Huo was in the corner, touching the small holes in the wall where nails had been driven in. He said, "I helped Fang Ze hang a whiteboard on this wall ten years ago. We've replaced the whiteboard three times. The holes in the wall are still there."

Lu Yunfei was the last to enter. He didn't speak, but stood at the door for a while before walking to the whiteboard and adding a line below what Shen Yiming had written: "Start drawing the blueprints for the next ship from here."

At the core team meeting, Zuo Cheng announced the next phase's core mission: to build a Web-like deep-space spacecraft. The target is the Proxima Centauri system, with a range of 4.2 light-years.

He listed three options on the whiteboard.

The first scenario is a century-long voyage, where a generation of crew members spend their entire lives on the spaceship.

The second type is a hibernation system, in which the crew is in a state of biological stagnation during the voyage and is automatically awakened upon arrival.

The third method does not require hibernation. It involves remotely controlling a Centaur robot avatar through an interstellar consciousness network, transforming "arrival" from a physical concept into a conscious one.

The three options sparked heated debate. Han Lu favored the third option, which was safe and did not require sacrificing anyone's life.

She said: "A four-year Pioneer mission is risky enough. A hundred years is another level. We have no right to let anyone live or die on the ship."

Chen Hao favors the second option, as hibernation technology already has a foundation and can be achieved within a few years. He says: "Hibernation isn't about stealing time. It's about making time wait for us."

Fang Ze sat in the last row without saying a word. He drew a question mark on the NX chip design diagram.

Liu Wei patted him on the shoulder and said: "Can your chip reach 50% of the speed of light?"

Fang Ze said: The current architecture is no good. It's barely 0.5%.

Yu Ying remained silent for a long time. Then she asked Zuo Cheng: Which one do you want to choose?

Zuo Cheng said: The fourth type.

Yu Ying waited for him to say.

Zuo Cheng said: "Shorten the sailing time to less than ten years."

A hundred-year voyage is tantamount to sending a ship full of people to their deaths. Hibernation is tantamount to stealing people from time. Remote consciousness is tantamount to locking people on Earth. I do not accept any of these three.

Yu Ying said: Within ten years, spacecraft need to reach 50% of the speed of light. Currently, the fastest spacecraft ever built by mankind hasn't even broken through 0.5%.

Zuo Cheng said: I know. So we need the next breakthrough.

The meeting room fell silent.

The core team discussed the last question: who would fly the maiden voyage of the Web-class spacecraft?

Han Lu said: Last time it was Ji Beihang. This time we can recruit openly. Out of the eight billion people in the world, there are definitely more than six people willing to go to Centaurus.

Chen Hao said: Recruiting is one thing. But the maiden voyage needs people who can handle any emergency. Not volunteers, but experts.

Shen Yiming leaned back in his chair, staring at the ceiling. He had written 1102 entries in his journal on the Pioneer. At that moment, he uttered a sentence: "The people on the maiden voyage didn't just fly there. They lived there for all of humanity."

Zuo Cheng did not join the discussion. He sat in the corner with a piece of paper in front of him.

The paper contained the initial design parameters of the Web-type spacecraft: approximately 500 meters in length, 50 crew members, and a target speed of 50 percent of the speed of light.

He wrote a small line next to the parameters: If no one can fly, I will.

Yu Ying saw the line of text. She didn't speak. She turned the paper over and continued drawing her orbital mechanics sketch. But her hands were trembling.

That evening, Zuo Cheng and Yu Ying told Zuo Weiyang a story at home.

Zuo Cheng was talking about the Pioneer expedition. When he got to the moment the Pioneer turned around at the edge of the solar system, Zuo Weiyang yawned and fell asleep in her mother's arms.

Yu Ying put her in the crib and returned to the living room.

Zuo Cheng sat on the sofa, holding a storybook in his hand.

Yu Ying sat down next to him. She remained silent for a long time. Then she said, "If you want to fly, I'll go with you."

Zuo Cheng turned to look at her. Yu Ying said, "Not as the chief scientist. As Zuo Weiyang's mother and your wife. If my daughter asks me in the future, 'Where was Mom when Dad went to Centaurus?' I can't answer her, 'Mom was in the control center watching his spaceship fly away.' I will answer her, 'Mom was beside Dad. Flying together.'"

Zuo Cheng took her hand. Yu Ying's fingers were cold. She had just put Zuo Weiyang into the crib and tucked the blanket in twice. Her hands were steady when she did these things. But now, holding Zuo Cheng's hand, her fingers were trembling.

Outside the window, the Pioneer's tracklight slowly streaked across the near-Earth orbit in the night sky. Its first night flight after four years of expedition. Like an old friend waving to someone on the windowsill. Zuo Cheng didn't answer. But he held Yu Ying's hand tighter than ever before.