It was around 11:30 a.m. on June 24.

In the space port area of the Tiangong space station, the spacecraft of the Houyi and Chang'e spacecraft have completed their rest and replenishment, all the materials that need to be loaded have been loaded, and the huge hatch is slowly closed, quietly waiting for the command to go to the moon.

"Flying around the ground~"

Soon, the command from the ground command and control center was transmitted to the two spacecraft and the 'Tiangong' space station.

The mechanical arms that held the two spaceships in place slowly loosened, and the two spaceships began to slowly fly away from the space station and begin to fly around the earth in orbit around the earth.

The reason why you choose to fly around the earth, rather than directly choosing the direction of the moon and flying over, involves the initial speed of the spacecraft.

The distance between the Earth and the Moon is about 360,000 kilometers to 400,000 kilometers, with an average distance of 380,000 kilometers.

Because the distance is too far, the spacecraft must gain enough speed, otherwise it will take too long, which will be a test for the materials carried on the spacecraft and the astronauts.

Orbiting the Earth, relying on the Earth's gravitational pull, the spacecraft orbits around the Earth in an elliptical orbit, which is slow at perigee and fast at apogee.

Because the gravitational pull of the earth can be relied on to give the spacecraft a good initial velocity, it can greatly reduce the energy consumed by the spacecraft to accelerate.

The 'Houyi' and 'Chang'e' spacecraft are constantly flying around the earth in orbit around the earth, and through the adjustment of orbits, the speed of the two spacecraft is getting faster and faster.

"Fly to the Moon~"

When the time came to 12 o'clock, the order from the ground command center was conveyed again.

The 'Houyi' spacecraft had just flown to the apogee of the orbit at this time, and when it was at its fastest,

"Boom~"

The auxiliary fuel propulsion system on the 'Houyi' spacecraft began to work, and a bright tail flame erupted from the back of the spacecraft, which continued to elongate in space, and soon turned into a long tail.

With the help of the auxiliary power system, the 'Houyi' spacecraft got rid of the earth's gravity very smoothly and sped rapidly towards the moon.

At this point, with the help of the Earth's gravitational pull, it gains a decent initial velocity of 20 kilometers per second.

If it flies to the moon at this speed, it will take about six hours to reach the moon.

However, the speed of the spacecraft is still not enough, and the fuel propulsion system on the spacecraft is still constantly spraying flames, slowly accelerating it, and it will stop working when the speed reaches 40 kilometers per second.

Behind the 'Houyi', the 'Chang'e' spacecraft soon broke free from the shackles of the earth's gravity in the same way, dragging its long tail towards the direction of the moon.

The speed of the two spacecraft continued to increase, and after half an hour, they reached a set speed of 40 kilometers per second, the auxiliary power system was turned off, and the spacecraft began to fly towards the moon in the void by inertia.

Flying in interstellar space, the most energy-consuming is in the two phases of acceleration and final deceleration, and the time and distance in between can hardly consume any energy, and only need to rely on inertial flight.

And there is a deep reason why the two spacecraft stopped accelerating after accelerating to a speed of 40 kilometers per second.

According to Einstein's mass-energy formula, we all know that the faster the object, the greater the capacity it can carry, and the faster you accelerate the speed of an object, the more energy it will take.

Once the spacecraft reaches a speed of 40 kilometers per second, continue to accelerate it, and the energy consumed will become greater and smaller.

It is very likely to cost 1 unit of energy, and its speed can only be increased slightly, which is very uneconomical.

What's more, when you get to the moon, you'll also need to slow it down, and the faster you go, the more energy it will consume.

Therefore, after comprehensive consideration and calculation, after fully considering the energy carried by the spacecraft, the speed set at 40 kilometers per second is the most appropriate.

In the vast and vast void of the universe, the 'Houyi' and 'Chang'e' spaceships are like two small fireflies flying in the endless void.

Although they are already very fast, nearly 40 kilometers per second, this is definitely the fastest speed of mankind at present, and it can only be achieved in the environment of space.

But compared to the vastness of the universe, the two spaceships seem to have never moved at the same origin.

In the vast starry universe, you may even have the illusion that you seem to be stationary, always at a point.

No matter from that place, there seems to be no change, the starry sky is still a starry sky, pitch black, dim, the stars are shining, and the road ahead seems to be endless.

Only when you look back at the earth after half an hour will you find that the earth seems to be slowly getting smaller, and the moon in front of you is slowly getting bigger in the field of vision.

The two spaceships stopped accelerating, and the astronauts on board fell asleep.

They need to maintain a high level of energy and stamina, and the process of inertial flight takes several hours, just enough for them to get a good night's sleep.

When they reach the moon, exciting times will come, and more importantly, there are many tasks waiting for them, and then it will not be so easy.

These astronauts usually have special training, saying that they will soon fall asleep one by one, and if they are an ordinary person, it is estimated that they will not be able to sleep at all at this time.

Because the moon is slowly getting bigger in the field of vision, it exudes a bright brilliance, which attracts people's attention, and the earth behind it also exudes a bright brilliance at this time, which is very beautiful.

The earth's ground control command center did not disturb the astronauts' rest for the time being, and the automatic control system on the spacecraft kept in touch with the earth's side at all times.

Qin Yi was a little bored, there was nothing to do when the spaceship was flying by inertia, and it was the safest time.

After thinking about it, Qin Yi returned to his dormitory and prepared to take a nap, many scientists, engineers, etc. also had the same plan as Qin Yi at this time.

Astronauts in space need to maintain high energy, and these scientists and engineers are the same, because when the real moon landing, scientists and engineers have to be busy, and now they also need to seize the time to rest.

Qin Yi returned to his dormitory, habitually took out his mobile phone and prepared to see if there was anything going on with the company, there was nothing on the company's side, but Wen Xueying sent a lot of messages from his side.

Qin Yi saw the message, his face was full of happiness, and after thinking about it, a love poem emerged and sent back.

was about to turn off his mobile phone and take a nap, and a message popped up on WeChat, not surprisingly about the news of this manned landing on the moon.

The TV station broadcast the whole process live, which relied on inertial flight during this period of time was also very boring, so I also invited several experts and scholars to start playing their role and began to popularize some interstellar space knowledge of the universe.

Qin Yi clicked in and began to look at it with interest.

"As you can see now, the auxiliary power systems of the Houyi and Chang'e spacecraft have been turned off and they have begun to fly by inertia in space."

"In space, because there is no air, theoretically speaking, it does not have any friction, so relying on inertial flight is the most energy-saving stage."

"According to my calculations, the two spacecraft will probably fly by inertia for more than 2 hours, after which it will start to slow down."

"Why slow down?"

"Because the gravitational pull of the moon is very small, of course, this is compared with the earth, because the gravitational pull of the moon is small, so once the speed is too fast, the gravitational pull of the moon will not be able to capture two spaceships, and the two spacecraft are likely to pass by the moon."

"So the manned landing on the moon, the really dangerous stage, whether this can be captured by the moon's gravity is one, once the speed is too fast, and the moon passes by, it will be bad."

"So the speed of the two spacecraft would have to be reduced to a certain point, reduced enough to be captured by the moon's gravity, and the process would be very time-consuming."

"The gravitational pull of the moon is too small, its escape speed is only 2.4 kilometers per second, and now the speed of the spacecraft is 40 kilometers per second, so it is conceivable that it will take a long time for the spacecraft to slow down."

"This is a very important key point in the next ~"

"Okay, thank you Professor Zhang for sharing the knowledge for us, originally I thought that I could fly directly to the moon at this speed, but now it seems that there is still a lot of knowledge about the routes in this interstellar universe."

"Next, I would like to invite Expert Wang to share some of his views with us."

"Okay, in fact, Professor Zhang has said a lot just now, and he has said a lot, the most energy-saving way to sail in the interstellar universe is to use the gravitational pull of massive celestial bodies, such as the earth, the moon, Mars, and so on, to accelerate and decelerate."

"The Wandering Earth, which was popular a few years ago, why did you get close to Jupiter first in the process of wandering, in fact, it was to use Jupiter's huge gravitational pull to gain greater acceleration......"

Qin Yi watched it for a few minutes and immediately became interested, although the content of these experts and professors who were invited to the TV station to give guest lectures was not wrong, it was still good to popularize science and science to ordinary people, and it was able to let ordinary people know and understand some knowledge of astronautics.

But for a scientist of Qin Yi's level, there is no need to learn at all, and Qin Yi has long been familiar with these things.

"It's also good, give more science popularization and popularization to ordinary people, and increase everyone's knowledge of space science, but the content still needs to be slightly guided, mainly to depict space as gold everywhere, so as to attract more people to devote themselves to interstellar space."

"You can talk more about the resources and minerals on the moon, and interests are the biggest driving force~"

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