Humanity Is Gone, but I Have Billions of Clones

Achieving the high maneuverability and acceleration required for an Interstellar Missile was clearly impossible with chemical fuel.

The only viable solution was to install a secondary-pressurization thrust device inside the Missile and let it propel the Missile forward.

But an Interstellar Missile weighed five to six tons at most, and as little as a few hundred kilograms. Installing a secondary-pressurization thrust device into such a small frame was practically impossible.

Even after successfully miniaturizing the secondary-pressurization thrust device enough to install it on a Mercury-class Spaceship, Li Qingsong had continued to tirelessly research ways to make it even smaller.

During this time, Li Qingsong had indeed made some progress, further optimizing its performance and reducing its mass and volume. However, it was still a long way from being small enough to fit inside a Missile.

Perhaps he could achieve it in the future as his technology advanced, but it was clearly impossible in the short term.

’Then I’ll scrap that idea! I’ll find another way!’

Li Qingsong gritted his teeth and decided to take a risk.

He planned to use a completely new design for the thrust device.

A Separable Nuclear Detonation Thruster!

Nuclear fission power plants and engines both use controlled nuclear fission, releasing energy in a gradual, manageable way.

Uncontrolled nuclear fission is a nuclear explosion, the kind used in an atomic bomb.

Now, Li Qingsong planned to strike a compromise between the two.

A key factor in controlling the fission rate of uranium-235 or plutonium-239 is the neutron moderator.

Control the neutrons, and you can control the rate of nuclear fission.

’In that case... I’ll just put weapons-grade uranium or plutonium that has reached critical mass directly into the Missile’s engine and use a large amount of neutron moderator to slow down its fission rate.’

But this could only slow the reaction; it couldn’t stop it completely. In other words, once the fission began, it would accelerate continuously until it finally detonated like an atomic bomb.

However, even just slowing it down was sufficient.

Conveniently, Li Qingsong had no plans for a secondary-pressurization process anyway. He would use the propellant itself as a coolant. As the propellant absorbed energy from the nuclear fission reactor to cool it, the propellant would simultaneously be pressurized to a temperature and pressure far beyond what ordinary chemical combustion could achieve, before being ejected directly from the nozzle.

The missile Li Qingsong envisioned didn’t even need a warhead.

Its engine was, in essence, a nuclear bomb—just one with a suppressed fission rate. A portion of the fission energy was simply being siphoned off for its own acceleration.

Once it reached the end of its acceleration phase, with both the propellant and neutron moderator depleted, it could only detonate like a nuclear bomb.

Given this design, the Missile’s engine obviously couldn’t store the fissionable fuel. The fuel would have to be loaded immediately before launch.

This was the so-called separable design.

Combine that with its inevitable finale—a violent nuclear explosion—and that was Li Qingsong’s concept: the Separable Nuclear Detonation Thruster!

No one had ever conceived of this kind of Interstellar Missile before. Li Qingsong believed that even an alien civilization with technology more advanced than his own likely wouldn’t have such a Missile.

The reason was simple: it was a temporary, stopgap solution born from an urgent strategic need, limited by his current technological capabilities.

A more advanced civilization would have superior technology; they wouldn’t need to resort to such a deeply flawed design.

Now, built according to his concept, the first Interstellar Missile powered by a Separable Nuclear Detonation Thruster appeared before Li Qingsong, then was taken into space.

If anything went wrong, this thing would turn into an atomic bomb, so he didn’t dare to conduct the experiment on the ground.

The Interstellar Missile was shaped like a hemisphere, bearing no resemblance to a traditional missile.

But there was no air in space, so aerodynamic optimization was unnecessary. The shape didn’t matter as long as it could be propelled effectively.

A robot retrieved the uranium-235, which had reached critical mass but was divided into three parts, and carefully installed it into the engine.

Immediately afterward, the experimental equipment withdrew.

Watching it from a distance, Li Qingsong began the countdown.

He knew that even though the engine was flooded with neutron moderator, the neutron count within it was still slowly rising. Soon, it would begin to accelerate.

Fifty seconds after the countdown began, just as expected, blue flames erupted from the nozzle at the base of the hemisphere.

At first, the flames were weak, only managing to push it forward slowly. But as the fission reaction sped up, the energy released grew immense. The flames shifted from blue to a fiery white, and their ejection grew more and more violent.

The hemispherical Missile’s speed increased faster and faster. In less than a minute, its acceleration had surged to 10 meters per second squared, and it was still climbing rapidly!

At this point, even if Li Qingsong had wanted it to slow down or stop accelerating, it was impossible.

The chain reaction had already begun, and Li Qingsong had no way to stop it.

The most Li Qingsong could do was change the direction of its thrust to make minor adjustments to its trajectory.

The hemispherical Missile flew through space for about half an hour, covering a distance of over 100,000 kilometers. Then, just as its speed peaked, the rate of the chain reaction finally spun completely out of control. Under the bombardment of countless neutrons, nearly all the fissionable fuel was drawn into the reaction. A tremendous amount of energy was released in an instant, and the Missile detonated, transforming into a giant fireball.

At that moment, its velocity had reached a staggering 80 kilometers per second!

This far exceeded the baseline of 40 kilometers per second that Li Qingsong had initially set!

’This thing is great and all, but it has a few drawbacks.’

Li Qingsong sighed. ’First, once it starts accelerating, it can’t be stopped.

Second, a single Missile consumes over 20 kilograms of precious fissionable fuel.

Third, its initial velocity is slow. It needs a period of acceleration to reach a sufficient speed, and this is its most dangerous phase, when it’s easily destroyed.

Fourth, this thing is just too dangerous. If it were to blow up before it even launched, well, that would be a catastrophe...’

A close-range atomic detonation would vaporize even an Earth-class Warship in an instant.

However, when he thought about his military system, he realized he had no other weapon that could fill the "long-range, high-power" niche. Li Qingsong could only brace himself and accept it.

’I’ll just have to iterate and optimize it as best I can,’ he thought. ’I’ll do everything possible to improve its safety and reliability...’