Great Country Academician

For Xu Chuan, sending a space shuttle into outer space is just the most basic goal in developing aerospace technology.

His goal is to realize the transportation of resources between the earth and the moon, and even the colonization between earth and fire.

The foundation of all this is based on mature and high-speed aerospace technology.

However, this can be said to be a ‘luxury hope’ for current aerospace technology.

Take the United States' Apollo 1 lunar landing spacecraft as an example. It took more than eight days to travel from the earth to the moon, let alone return.

This has something to do with its launch method, technology and other aspects.

When the Apollo lunar landing spacecraft was launched, the spaceflight did not directly accelerate into the Earth-moon transfer orbit segment, but made various orbital maneuvers to go to the moon.

Its entire flight process can be divided into four orbital segments: entering the Earth orbit segment, orbiting the Earth orbit segment (also known as the steering orbit segment), Earth-moon transfer orbit segment, and orbiting the Moon orbit segment.

First, astronauts need to take a rocket to lift off from the danger center on the ground and then enter the earth's orbit. This time is 16 hours.

After orbiting the Earth, the vehicle will ascend to another orbit, farther from the Earth and closer to the moon. In this orbit, the aircraft needs to fly for another 24 hours before making the next move.

This is the first time the track segment has been redirected.

Subsequently, the aircraft ascended to the 48-hour orbit again, which was the second time to adjust the orbit.

After flying around the earth twice, it still cannot fly directly to the moon. It still needs to ascend to orbit in a 48-hour cycle and make a third orbit adjustment, moving away from the earth in a wider range and approaching the moon.

After completing three orbit changes, the spacecraft can begin to accelerate towards the moon. This process takes about 5 days, which is 120 hours.

As it approaches the lunar orbit, it is captured by the moon's gravity.

After entering the lunar orbit, the spacecraft will stay in the 200-kilometer orbit of the moon and begin to slow down.

After deceleration is completed, a safe landing on the lunar surface can begin.

Before and after, various complex orbit changes, various orbits around the star, and the entire flight process took more than eight days to finally complete a moon landing, which shows how difficult it is to land on the moon.

And this is just the moon, when the average distance between the earth and the moon is only 380,000 kilometers.

If it were to land on Mars, even in the closest period, the average distance between the Earth and Mars would be as high as 55 million kilometers.

Such a long distance would take more than a month or two.

Judging from current aerospace technology, it will take at least half a year to reach Mars from Earth.

For others, this time may be quite short.

But for Xu Chuan, this time took a bit too long.

It takes half a year to complete a Mars landing. With current aerospace technology, the time required to establish a scientific research base or colonize Mars may be measured in hundreds of years.

In the office, when faced with this problem, Academician Chang Huaxiang couldn't help but said: "I think you are a little too ambitious. We haven't even gone to the moon yet, and you are already thinking about landing on Mars."

Xu Chuan took a sip of the tea in his cup and said with a smile: "Although landing on the moon is difficult for us, it is not out of reach, right?"

"If it were just a moon landing, it wouldn't be much of a challenge for me, and it wouldn't be worth spending so much time and energy on leading this work. I believe there are enough talents in the domestic aerospace field who can take on this task. A mission.”

In fact, for Xu Chuan, landing on the moon is not his goal, and even landing on the fire is not his goal.

In his mind, there was a more ambitious plan than the two, but there was no need to say it out now.

After all, if you say that idea, currently, the entire society may not understand or support it. At most, it will give the disciples something to talk about that he is crazy.

On the sofa, listening to Xu Chuan's heroic words, Chang Huaxiang sighed: "You young people still have ideas, goals and bottlenecks. I don't know if I will see a manned landing on Mars in my lifetime."

After sighing, Academician Chang then began to think.

After a while, he said: "There are many ways to shorten the time to land on the moon or the fire."

"How to say?"

Chang Huaxiang thought for a while and said, "If you want to shorten the time, there are two most effective ways."

"The first one is to increase the speed of the spacecraft by consuming fuel (working fluid) through the thruster. You also know very well that the faster the speed of the spacecraft, the shorter the time to the moon and Mars will naturally be."

"However, this has extremely high requirements on the performance of the spacecraft or aerospace engine, as well as fuel and other aspects."

After hearing the first solution, Xu Chuan thought briefly and understood what Academician Chang Huaxiang was thinking.

As we all know, when the distance is fixed, regardless of other factors, the faster the forward speed, the shorter the time required.

When traditional manned space missions go to the moon, Mars and other extraterrestrial planets, they almost maintain a constant speed for a large part of the road.

For traditional fossil fuel rockets, this is almost impossible to achieve.

Because the thrust-to-weight ratio limits everything, it is impossible for landers and spacecraft to carry a large amount of fuel to do this.

Traditional spacecraft cannot leave a lot of space and weight to carry fuel, whether in terms of design, functionality, or its own load and launch weight.

Each orbit change, acceleration, deceleration, etc. requires a large amount of fuel to complete.

This also limits humans' ability to explore other planets.

After all, if you want to recover the probe or send astronauts there and then recover it, the endurance of the spacecraft is the biggest problem.

However, for a space shuttle that uses miniaturized controllable nuclear fusion technology as energy, there is no need to worry about energy issues.

The energy released by deuterium and tritium fusion is thousands of times that of fossil fuel combustion. One ton of deuterium and tritium raw materials is enough to complete a manned moon landing.

Compared with fossil fuels, although part of the liberated space will be used for the storage of aerospace working fluids, there is no doubt that the remaining space is enough for astronauts to survive on the spacecraft for a longer time or to carry more supplies. .

"What about the second way to shorten the time?"

The first way is very simple. With the efficiency of a miniaturized and controllable nuclear fusion reactor, it is not difficult to increase the speed of a spacecraft.

At this moment, Xu Chuan was more curious about another way to shorten the space flight time.

Chang Huaxiang smiled and said: "The second method has higher requirements for aerospace technology and is a bit risky."

"How to say?"

"Omit the orbit adjustment of the spacecraft during manned moon landing or fire landing, and directly land on the moon in outer space orbit!"

Hearing this, Xu Chuan glanced at Academician Chang Huaxiang in front of him in surprise, frowned slightly and said, "Isn't the risk too great if we omit the orbit adjustment?"

Although he is not a scholar in the field of aerospace, he does not know anything about aerospace.

At least these days, he has gained a lot of aerospace knowledge.

As mentioned earlier, when the spacecraft goes to the moon, it does not go straight to the moon. Instead, it needs to continuously change orbits around the earth and the moon to adjust its orbit.

The main reason for this is the shortcomings and differences in aerospace technology and theory.

Needless to say about technology, in order to improve rocket efficiency, almost all chemical rockets currently adopt a multi-section rocket design.

At the same time, the irregular shape of the aircraft determines that when it is left on the rocket, protruding parts such as solar panels and antennas must be folded and fairings must be placed on the outside.

Therefore, after the last rocket section is abandoned, the lunar lander will need a certain amount of time to separate, deploy, power on, test and other processes.

Especially in the testing phase, you can't wait until the aircraft arrives near the moon to discover that the aircraft has a fault and needs to be repaired, right?

There are also reasons for orbiting to adjust the deployment and test whether the spacecraft is working properly.

The theory lies in the fact that the basis currently used in the aerospace field is a theory called 'Homann transfer orbit'.

This is knowledge in high school physics that is often tested in both college entrance examinations and competitions. It is a method of changing the orbit of a spacecraft.

Using Hohmann transfer orbit, the spacecraft can significantly modify its orbit with only two engine thrusts during the orbit change, which can save a lot of spacecraft fuel.

After all, in reality, the larger the orbital parameters change in each orbital maneuver, the higher the requirements for engine thrust. It also requires longer working time and higher control accuracy, which means there will be greater risk.

Multiple orbits are also an important means to reduce risks and ensure the safety of spacecraft and astronauts.

If astronauts need to take higher risks to reduce the time of landing on the moon, Xu Chuan is unwilling to accept it.

Although he hopes that technology can be improved, it cannot be based on the sacrifice of astronauts.

Hearing Xu Chuan's concerns, Academician Chang Huaxiang nodded in praise.

He proposed this method because he wanted to see what the young scholar in front of him thought.

After all, this is the first time I have met and cooperated with him. Although I have heard many stories about him, I know his face but not his heart.

In academia, paranoia is a trait shared by most scholars. It is a double-edged sword that can normally help a person keep moving forward on the road of learning and research.

But if you are too paranoid, you will go crazy.

Sometimes, some researchers are so paranoid about technology or scientific research that they are desperate.

For example, some people who are engaged in biological research often regard life as if it is nothing and are crazy.

Chang Huaxiang naturally didn't want the person in front of him to have this idea. Although he really wanted to realize the dream of a space shuttle, he didn't want to use his abilities in the wrong place.

After all, given the current domestic status and ability of the person in front of me, once there is any deviation, it will be a huge blow and loss to the development of domestic academic circles.

But now it seems that the person in front of me still has a good idea.

Smiling, Chang Huaxiang said: "Omitting the orbit adjustment during the moon landing or fire landing is very difficult to do on a traditional lunar exploration ship. After all, the traditional launch vehicle needs to complete the space flight after reaching the high orbit. The deployment of the device and other tasks.”

"But for the space shuttle, it is not unfeasible to save this step, or to shorten the orbit adjustment time."

"The space shuttle has many advantages over traditional spacecraft. It does not need to deploy additional solar panels, antennas and other equipment, which is enough to eliminate a large part of orbit adjustments."

"And more importantly, after the breakthrough of miniaturized and controllable nuclear fusion technology in your hand, energy is no longer a constraint for it."

"The huge size means that the space shuttle can carry more supplies, and sufficient energy can ensure that it can make adjustments even after it deviates from the orbit."

Speaking of this, Xu Chuan also understood what Academician Chang Huaxiang meant. He thought: "Just like an ordinary civil aviation aircraft, although the flight route is fixed at the beginning, it does not mean that it has no ability to modify the route. Yes, that’s what you mean, right?”

Chang Huaxiang smiled and nodded, saying: "Yes!"

"Traditional spacecraft do not have such conditions because their design ideas do not follow this route, but the space shuttle does, and this is its advantage."

"Especially after the energy problem is solved, during space navigation, it can communicate and re-lock the target and direction at any time like an aircraft in the atmosphere."

After a pause, he continued: "However, this method may require relatively high computing power, especially if the orbit is adjusted in real time."

Xu Chuan smiled and said: "This is no problem, just build a supercomputing center."

Hearing this, Chang Huaxiang's mouth moved, but he stopped talking.

He wants to ask if you know how much a supercomputing center costs? Even if it is a special type, for aerospace, the price may exceed nine figures.

With this money to build a supercomputing center, I am afraid it is enough to launch double-digit or even triple-digit satellites into the sky.

Even for the funds required to land a man on the moon, this is not a small number.

Is it really inhumane?

Xu Chuan didn't think much about it. The supercomputing center was really a trivial matter to him.

What's more, supercomputing centers are not disposable items. As time goes by and space missions increase, supercomputing centers will only become more cost-effective as they are used.

After thinking for a while, he said: "Academician Chang, you are an expert in the aerospace field. If I leave the work related to the space shuttle to you, how long will it take to complete it?"

After hearing this question, Chang Huaxiang thought for a while and said: "Two years, within two years I can guarantee the completion of the production of at least one space shuttle."

"too long."

Xu Chuan shook his head. In two years, the day lily has become cold.

Chang Huaxiang said helplessly: "This is already a very short time. We have not made much development on the space shuttle route. The relevant designs and ideas need to be adjusted repeatedly."

"In addition, there are some technologies on the space shuttle that need to be overcome, such as the outermost insulation tiles, as well as the manufacturing and assembly of parts and equipment, which all take time."

Xu Chuan shook his head and said: "Judging from the current situation, if we want to be the first to land on the moon before the United States returns to the moon, we have less than a year at most, or even only about half a year."