Setting Sail

After reaching the fifth stage, Hope would maintain a rotational speed of roughly 1.27 rpm to provide artificial gravity, then set out on its starward journey.

Although humanity had lived on Callisto for decades, it was still far inferior to Earth. Whether in terms of physiological structure, cellular memory, growth process, or genetic information, humans had evolved entirely to adapt to Earth's environment.

More than four billion years had passed since the birth of the first single-celled organism.

Therefore, no matter the era, Earth's gravity environment was the most suitable for humanity.

For this reason, the New Government had decided that Hope's final simulated gravity would be set to a value similar to Earth's environment.

And a rotational speed of 1.27 rpm avoided the harmful effects of the Coriolis Effect on humans. It could be said that Hope's design had achieved its intended goals.

More than a month passed quickly. During that time, the spacecraft's rotation speed gradually increased stage by stage, and after round after round of adaptation, people once again regained the feeling of Earth's gravity environment.

In theory, if hibernation time was included, most people had already lived under Callisto's environmental conditions for decades. There was no way they should have been able to readapt to Earth's gravity environment in just over a month.

However, due to the needs of space development, humanity had already developed certain drugs to assist with this adaptation process long before the disaster occurred.

After the human body adapted to a microgravity environment, the fluids throughout the body decreased by a full liter. Furthermore, because the cardiovascular system no longer needed to overcome gravity to supply blood to the brain, cardiac muscle function gradually weakened as well.

To return to an Earth-like gravity environment, a gradual process was necessary.

"Hope, set sail! Destination: Ross 154!"

After everyone had adapted to the spacecraft's environment, Yue Yuan finally gave the order he had longed to give for more than forty years.

This destination had not been chosen casually. It was the best destination determined after decades of observation by astronomers.

By normal logic, heading for the nearest star should have been the best choice. However, Proxima Centauri, the closest star, along with the Centaurus Trinary Star System it belonged to, had already exploded. Naturally, humanity could not go there.

So the scientists had to choose another destination.

After decades of comparing Callisto's drifting direction and speed through space, the movement direction of the dust cloud after the Supernova Explosion, and several stars closest to humanity, while considering such factors as the number of planets and possible resource distribution, they finally reached their conclusion: Ross 154.

There was actually a closer star, Wolf 359, only 7.7 light-years from Earth. It had originally been the first-choice destination, but its system contained only two planets: one Rocky Planet and one Gaseous Planet.

According to scientific observation data, that Rocky Planet was close to its Main Sequence Star. Judging by its orbital position and the star's surface temperature, the planet's surface temperature was highly likely to remain between 480 and 500 degrees Celsius.

Humanity simply could not extract resources from a planet with such a harsh environment.

Ross 154, on the other hand, was much better. Through the Radial Velocity Method, humanity had learned that it possessed seven planets. Two of them were likely Giant Gas Planets, while the other five were Rocky Planets. More importantly, none of those five Rocky Planets were the closest to the Main Sequence Star. The so-called Radial Velocity Method was, simply put, a method of detecting whether a star system had planets by observing the gravitational interactions between planets and their star.

It was one of seven methods for detecting exoplanets. Broadly speaking, it measured the gravitational effect a planet had on its Main Sequence Star. As a planet orbited, its gravity caused the star to "wobble" slightly. The larger the planet, the greater its effect on the star.

This stellar "wobble" could tell people how many planets a star system had and how large they were. Because it captured the tiny motions toward or away from Earth caused by planets orbiting their star, this technique was also called the Doppler method. It measured shifts in starlight caused by gravity—in other words, changes in the light's color.

Scientists inferred that besides the five Rocky Planets, there should also be many satellite systems. To humanity in its current state, that was practically heaven.

Moreover, although Ross 154 was a Red Dwarf Star with a surface temperature of only 3,470 Kelvin, or 3,196.85 degrees Celsius, with humanity's current technology, as long as a star emitted light, there was a way to obtain energy from it.

With Yue Yuan's order, Hope—the spacecraft carrying all of humanity's hopes—finally embarked on this long journey of 9.545 light-years.

Ross 154 had originally been about 9.693 light-years from the Solar System, but Callisto had carried humanity part of the way. Thus, when Hope set sail, the distance had become 9.545 light-years.

The glow of nuclear fission illuminated dark Callisto, and azure flames lit up the silver Hope.

Hope, positioned in Callisto's synchronous orbit, began to slowly change orbit under the thrust of three massive Fission Thrusters.

Its orbit began to shift from circular to elliptical.

Yes, unlike the grand, badass interstellar voyages in novels, Hope did not immediately shoot outward from Callisto's synchronous orbit. It had to change orbit, change orbit again, and change orbit once more, then fly out with Callisto's gravity assisting it.

That was right—a Gravity Slingshot.

Although Callisto's mass was pitifully small and it was utterly unsuitable as a Gravity Slingshot body, humanity had nothing left besides Callisto.

Humanity, short on energy, naturally had no intention of wasting any force it could use. Besides, it needed to correct Hope's direction of travel during the orbital changes.

Gradually, Hope's circular orbit became elliptical, then flattened out.

In the days that followed, Hope circled Callisto like a comet, sometimes farther away and sometimes closer. At the same time, the humans aboard Hope prepared for the final acceleration lap.

"All parameters corrected. Hope is about to enter the acceleration phase."

Hope-filled announcements rang out once more from the Command Center.

"Hope's attitude adjustment is complete. It is expected to enter the designated acceleration orbit in one minute and twenty-three seconds."

"All Engine Crew members are in position. The Main Thruster will enter full-power operation in one minute and twenty seconds."

"External camera signals are normal. Connecting to screens throughout Hope!"

Listening to the reports and announcements, Yue Yuan sat calmly in the captain's seat. The image on the large screen before him had now divided into nine sections, becoming nine exterior views arranged like a nine-grid display.

The images showed a partial view of Hope, long tongues of flame spewing from its thrusters, and endless dark starry space. Naturally, they also showed Callisto drifting farther and farther away.

"Goodbye, Jupiter's fourth moon—Callisto!" Yue Yuan silently said in his heart as he watched Callisto slowly fade from the screen.

Callisto still bore extensive traces of human industry, including many factories and enormous machines that could not be taken away. Humanity had not destroyed them. They would stand as proof that humans had once been there, accompanying Callisto on another wandering journey before vanishing into the boundless sea of stars.

Perhaps, if some civilization had extraordinary luck, it might encounter them in the distant future.

But that was no longer something humanity could concern itself with. In truth, there was another reason humanity had not blown up the remaining facilities and massive equipment: to conserve energy.

Just as Yue Yuan mourned Callisto, the light from Hope's thrusters suddenly intensified. The powerful reaction force allowed Hope to completely break free of Callisto's Gravity Field and slowly disappear into the boundless starry sky.

This was humanity's first interstellar voyage in history, and also a one-way interstellar voyage.

9.545 light-years was an unimaginably vast distance. Even traveling in the direction where the remaining Interstellar Dust had spread, humanity still could not afford a single mistake. But if it did not set sail, it would not even have a chance.