I ask you to build tractors, but you build rockets?

Chapter 378 Houston, we...

How long does it take to fly to the moon?

Light only takes 1.2 seconds, and the Apollo 11 spacecraft took 80 hours. In subsequent missions, the fastest record for manned spacecraft was raised to 69 hours.

Although it includes the time it takes to launch from the ground into low-Earth orbit, this is only ten minutes and can be ignored.

The straight-line distance between the earth and the moon is 380,000 kilometers. In theory, at a speed of 11.2 kilometers per second, it can be reached in more than ten hours. However, in fact, this is not the case.

Space flight is not a ground race. The moon is rotating around the earth, so the trajectory of the spacecraft is an arc instead of a straight line, and the speed of the transfer orbit is also changing all the time.

According to traditional astronomy, as long as the speed is higher than the first cosmic speed, the spacecraft can leave low-Earth orbit and fly to the moon, and the maximum speed is close to the upper limit of the second cosmic speed, which is less than 11.2 kilometers per second.

The reason for this number is that the Earth-Moon system is still within the second cosmic speed, that is, within the coverage of the Earth's gravity.

The moon itself is captured by the earth's gravity in order to orbit the earth. As long as the speed of the spacecraft is not higher than the second cosmic speed, it cannot escape the scope of the earth's gravity. When it reaches the moon, a lot of momentum has been consumed, and it will be decelerated if it slows down slightly and changes orbit. Lunar gravity capture.

If it exceeds the second cosmic speed, it means that it cannot be captured by the moon's gravity, and a lot of extra fuel must be consumed to slow down the speed.

Therefore, for traditional spacecraft and satellites, it is more appropriate to control the speed at 10 to 11 kilometers per second. In this way, on the way from the earth to the moon, the momentum will be gradually reduced by gravity by a maximum of 10km·s, and then decelerate again. You will be able to enter orbit around the moon in a short while.

The speed of Tempest in low-Earth orbit reaches 7.9 kilometers per second. If it also uses this orbit change method to go to the moon, it will only need three and a half hours to complete the required incremental speed acceleration, and then slowly wander over. The waiting time to be captured by the moon's gravity is more than three days, and it only consumes more than 1 ton of fuel, which is insignificant compared to its mass of more than 100 tons.

However, this test is certainly not for the purpose of saving fuel. This fuel-saving flight route is too wasteful for the Storm. What she is pursuing now is speed.

There are four stages of Storm's journey to the moon:

In the first stage, it accelerates around the earth from 7.9 kilometers per second to 11.2 kilometers per second and enters the transfer orbit, which takes 208 minutes;

In the second stage, the Tempest is already heading towards its destination on the Earth-Moon Transfer Orbit. The Tempest will experience an average deceleration of about 3.47 centimeters per second caused by the Earth's gravity every second. In this case, she will Continue to accelerate for about 90 minutes, increasing the speed to about 12.8km/s;

In the third stage, it takes about 25 minutes to shut down the engine, use the RCS system to turn around while taxiing, and prepare to slow down;

In the fourth stage, it will start the engine again and decelerate to the lunar orbit's orbiting speed of 1.68km/s. This process takes about 757 minutes, which is about 12.6 hours.

The entire acceleration phase covered a voyage of about 72,000 kilometers, the taxiing and U-turn phases were 18,000 kilometers, and the deceleration phase was the longest, about 310,000 kilometers. The total mileage was nearly 400,000 kilometers, and it took 18 hours to reach the moon.

Although it seems that the speed during flight is only slightly higher than the speed of the second universe, the Storm is starting the engine almost the whole time, consuming about 5 tons of fuel, compressing the flight time to the maximum limit of the engine technology, and decelerating for 75% of the journey. .

On the contrary, the Apollo spacecraft, which started at a speed of 10.8km/s, had already dropped to 800m/s when it arrived at the Lagrange L1 point of 324,000 kilometers, so it took dozens of hours.

This way of "wasting" fuel is completely unfeasible for rockets using chemical power and is far beyond the capabilities of traditional engines.

During the acceleration and deceleration process, the acceleration endured by Tempest is very small, only 0.265 to 0.34 meters per second, which is less than 0.03G. Therefore, even in the accelerated state, astronauts can leave their seats and move for a while, but they need to remind themselves at all times when acting. The object has acceleration to avoid accidents.

Similarly, the three nuclear engines that work continuously for eighteen hours will also be the longest-lasting spacecraft power in human history, and special attention needs to be paid to the operating conditions.

Of course, there are some small disadvantages, that is, because it is decelerating for 310,000 kilometers, the tail of the space shuttle is facing the moon, so the moon cannot be seen through the front portholes, and can only be seen through the extended camera. , the astronauts’ naked eyes can only watch the earth getting smaller and smaller in the porthole.

…

"Houston, we're in trouble."

Musk's voice suddenly sounded in the hall of the Houston Space Center.

Deputy Director Jim, who was fishing, was stunned for a moment, approached the microphone and replied:

"This is Houston, Elon, what's going on?"

"We discovered a UFO! It flew away from the Chinese space station!"

"..."

The rich man gave Jim an outrageous answer before Musk did, causing question marks to appear in the minds of the entire space center staff.

Musk: "We just used an optical telescope to observe the Advance, and found a... white, yes, I think there should be a white object nearly a hundred meters long that left the space station, and there was a pink color that might be several kilometers long. The tail flame, this can't be a rocket engine.

Billy recorded it all on a video recorder, and I'll send it to you right away! "

Musk's description was quite clear, and Jim immediately understood what the so-called UFO was, but shouldn't he?

"I am Jim, crew member of C209. You should know that the Chinese nuclear-powered aircraft has entered space. They are operating on the Advance space station. The tail flame of the nuclear engine is very fast. It is not a UFO."

Musk: "I originally thought so, but their direction is wrong. They are accelerating instead of decelerating. It is not going to enter the atmosphere."

Not entering the atmosphere?

Jim: "Then please send the video back first. Also, please don't panic. There may be a misunderstanding."

On the Dragon spacecraft, the Storm, which was accelerating at full power, had just flown out of the porthole. Shen Billy wanted to take out the SD card and send it, but Musk directly took off the electronic eyepiece, pointed the screen at the camera in the cabin, and replayed the video just now. .

The staff at the Houston Space Center immediately focused their attention on the video, and then saw a bright spot suddenly appearing in the center of the Progress and the acceleration process after the bright spot left.

Jim asked Musk to play it again and then affirmed:

"This is the Storm. It came out of the central section of the space station. And although the picture you showed us is a bit blurry, you can still see the tail of the space shuttle. Yes, that's it.

But I don’t know why it is accelerating. The video is too short. It may be that they are preparing to change orbit to find the Tiangong Space Station. This is normal. "