Su Han was completely dumbfounded at this time.

What the system says couldn't be clearer.

There's a wave of aliens coming to attack Earth.

And he needs to kill before the aliens come.

Build a spaceship and open the fire.

No way!

How could he be so unlucky!

Su Han didn't know what to say at this time.

Build an alien spaceship capable of interstellar wandering within fifty years.

Think about it and know it's almost impossible.

Because the most advanced rocket in his hand now is only capable of sitting a hundred or so people.

I want to escape across the stars.

At least tens of thousands of people should be brought with you!

Even if a spaceship with tens of thousands of people could be built, it wouldn't be able to fly.

Even if you have the ability to build a spaceship directly in space.

It's hard to propel this spaceship into the sky.

Although Su Han's ion engine capability is the world's first.

But at most, it can push the rocket to more than 100 kilometers per second.

The problem is that even if he can push the rocket to the speed of ten-thousandths of a light, it will be useless.

Because the closest star to Earth is also a few light-years away.

Even one ten-thousandth of the speed of light would take tens of thousands of years to fly.

At this speed, even if you fly yourself, you will become a dry corpse.

Su Han will naturally be a little big-headed.

I didn't expect such a thing to happen.

The point is that this kind of thing can't be consulted yet?

Because the system won't let you tell anyone.

I wonder if this dragon is considered a human being?

Su Han thought about it and decided not to take the risk.

But don't say it directly.

It's still okay to talk about it around the bush.

After all, it is impossible to build a spaceship as big as a big thing and let others know about it completely.

Su Han thought of this: "Divine Dragon! You say if I'm going to build a spaceship that can cross a star system. Is this possible? ”

Shenlong said: "Logically impossible. ”

"Why do you say that?"

"Because the distance between stars is measured in light years. With the current technology on Earth, the spacecraft can only be raised to 1/10,000th of the speed of light at most. At this speed, even if you fly to the closest star system to the solar system, it will take tens of thousands of years. Humans can't withstand flying for such a long time, either mentally or physically, they can't do it, and robots are okay. ”

Su Han frowned and said, "Isn't there that kind of hibernation warehouse in science fiction movies?" Can't you complete interstellar travel by sleeping? ”

Shenlong said: "The problem is that reality is not a science fiction movie. At present, the research on human metabolism is almost zero, especially the regulation of proteins and fluids in the state of deep sleep, so it is impossible to complete the so-called deep space sleep technology in a short period of time. And even if you have the technology, it's useless. Because deep space sleep only slows down the metabolic rate, and it cannot be completely stopped. It may not be a big problem for a few hundred years. Tens of thousands of years is simply impossible. ”

I have to admit that what Shenlong said is no problem.

But Su Han is different now.

He had the opportunity to open up advanced technology.

So he didn't think he could handle the deep space sleep technique.

Su Han thought of this: "If you let go of the deep space sleep technology, don't talk about it. What about the spaceship alone? ”

Shenlong said: "That's not very likely. Even if time is not considered, a long voyage across galaxies requires a ship and population large enough to complete the internal circulation. At least it must be able to carry tens of thousands of people. And the weight of the 10,000-person spacecraft may be as high as hundreds of thousands, or even hundreds of thousands of tons. Such a large spaceship would definitely not be built on Earth. Because even if you build it, you can't fly. It can only be built in low-earth orbit.

Want to make such a large spacecraft in low earth orbit.

Then there must be space elevator technology.

With the current material technology of the earth, it is not possible to complete such a huge space elevator.

And even if you can complete the space elevator.

It is also impossible to build such a large spacecraft in low earth orbit so that others do not know about it.

The countries of the world could not accept the boss building such a huge spaceship.

At worst, this could trigger a global storm, or even a war.

Therefore, the political boss could not complete the construction of such a huge spaceship. ”

Su Han also nodded when he heard this.

Want to build such a huge spaceship in Earth orbit.

It is simply impossible to support politically.

Even if the higher-ups supported themselves, it would be impossible for them to build such a huge spaceship.

Unless......

Unless it is not built on Earth.

Moon?

Definitely not.

It's too close to Earth.

Mars?

Mars though can.

But the goal is not small.

If a large amount of resources are transported from Earth to Mars.

It is simply impossible to hide from other countries.

Because each country has its own satellites in orbit around Mars.

So it is simply impossible to build a spacecraft on Mars.

Unless it's possible to go further afield?

Su Han thought of this and said, "Divine Dragon! You said that if I want to repair the plank road in the dark, Chen Cang. On the surface, under the pretext of immigrating to Mars, in fact, a spacecraft is being built in another place. Which planet do you think would be a good fit? ”

Shenlong said: "If it is a planetary-level place, then there is only Mercury." Mercury is relatively close to the Sun and has strong light, so building a spaceship on it should not be easy to spot. Moreover, Mercury is small in size, and if you build a space elevator, the difficulty is relatively lower than that of Earth, and more importantly, there are a large number of rare metals on Mercury. It helps a lot in building spaceships. The only problem is the large temperature difference between day and night. There are high requirements for the quality of materials. After all, high temperatures can easily cause mechanical problems. The durability of the equipment will be much worse.

Of course, there are some larger satellites that are also eligible. Such as Europa, Callisto, Titan. Of course, there are also some dwarf planets, such as Ceres between the firewood, and so on.

But I think the best is Mercury. Although Mercury is warmer, there are still suitable places. For example, at the junction of sunlight in Mercury's north and south poles, the temperature difference can be much different. And there are also huge craters in the Arctic and Antarctic regions. These craters form cold traps. It is also possible to try to build a base inside the crater. ”

Shenlong's suggestion, Su Han also felt very satisfied.

For Suhan, building a spaceship requires a lot of resources.

Although the moons of those large planets are not small, they are still much worse than real planets.

This is especially true for planets such as Mercury, which has a relatively high metal content.

The question now is whether the advanced technology that the system gives itself enough to build a ship that can sail across the star system.

If you use the current level of technology on Earth to build a spaceship.

It's no different from suicide.

Su Han thought of this and opened the list of skills.

It was found that all skills have been activated.

Including basic disciplines: Intermediate Mathematics, Intermediate Physics, and Intermediate Chemistry.