In space, there are two important indicators related to the performance of an engine, namely thrust and specific impulse. In simple terms, thrust determines the acceleration of a spacecraft, and specific impulse determines the final speed of a spacecraft. .

Theoretically speaking, the best way is to let an engine not only have extremely strong thrust, which can propel a spaceship to accelerate at a G acceleration, but also have a super high specific impulse [Note 1], which can make The DV of the spacecraft reaches the sub-light speed of tens of thousands of kilometers per second.

Unfortunately, in most cases, thrust and specific impulse are two contradictory properties.

If you want to increase the specific impulse, you must increase the fuel injection speed, that is, the injection speed, which can be understood as increasing the total thrust contributed by each kilogram of propellant.

But for a fusion engine, or for most engines, under the premise of a given power, if you want to increase the jet speed, you must reduce the propellant flow through the combustion chamber per second-it means The thrust contributed by this engine per second decreased.

And the decline is very, very serious.

This is not contradictory, although the contribution of thrust per second is reduced, but also the mass of propellant consumed per second is reduced even more, so that although the time required for acceleration increases hundreds of times, the final speed of the spacecraft The speed is still increased - power = thrust multiplied by the jet speed, assuming that the thrust drops to one tenth of the original, then the jet speed can be increased by ten times, and under the premise of the same load ratio, Dv will also increase ten times.

Obviously, for the interplanetary transfer of tens of millions or even hundreds of millions of kilometers, it is natural to spend hundreds of times the acceleration time to obtain a higher final speed—of course, the thrust should not be too low in actual operation. Otherwise, it will take a month to go to the moon, and no one can accept it.

This is also the biggest reason why it is almost impossible for electric pushers to be used as the main engine.

Electric propulsion is one of the typical ultra-high specific impulse engines - a ten-kilowatt Hall thruster, whose specific impulse reaches a specific impulse close to 100 kilometers per second, and the thrust is between millinewtons and newtons hovering.

Yes, not how many thousand newtons, but cattle, or even millinewtons.

A spaceship powered by pure electric propulsion can have a thrust-to-weight ratio of 0.001G, which is a shocking black technology—so, even if the specific impulse of electric propulsion is excellent and the final speed is quite high, basically no one will Consider using it for manned spaceflight.

This is also one of the reasons why warships need to carry so many working fluids—in order to increase the thrust, it will not take several years to go to Mars. They will selectively add additional working fluids to the engines, and by greatly reducing the jet speed way in exchange for higher thrust.

In fact, aircraft in the atmosphere also use a similar principle. The afterburner is a component that increases thrust by reducing specific impulse.

Generally speaking, dihydrogen monoxide is a very good working fluid—non-toxic, non-corrosive, easy to store, and extremely cheap to prepare. At the same time, its excellent specific heat capacity and thermal stability can also be used to cool down warships.

Moreover, this substance can be prepared in space without taking up valuable orbital capacity, which is really the best choice.

Although this substance is highly addictive, as long as humans stop contacting it for three days, they will die. According to medical research, this substance, also known as oxane, is a necessary component of almost all diseases, but due to its excellent The various properties of various countries still choose to load a large amount of this material on the spacecraft regardless of human life.

Stop using dihydrogen monoxide, start with you and me!

"It turns out that you also like to watch the Internet." Although he is not well-informed about outside information, he still has heard of this prank that has been widely circulated on the Internet. "How can people live without dihydrogen monoxide?"

"Stop talking, bring Lao Li a cup of dihydrogen monoxide."

The adjutant nodded, and called a cup of chemical solution mixed with high-concentration dihydrogen monoxide from the machine next to him.

"Boss, drink tea."

------

[Note 1: Specific impulse, also known as specific impulse, is defined as the impulse generated by the unit amount of propellant. The higher the specific impulse of the engine, the greater the speed increase that the propellant can produce under the same conditions, and the greater the engine efficiency. high.

Since the gravitational acceleration of Catus is different from that of the Earth, in order to avoid misunderstandings or bugs in frequent conversions, the paper uses mass description, which is expressed as jet velocity, and the velocity dimension is in meters per second (m/s).

There is a table in the penguin file to assist in the calculation. As long as you know any two of the specific impulse, velocity delta (DV) and fuel load ratio, you can calculate the remaining value. The picture here is too compressed to see clearly. If you want to see it, you can join the group to pick it up. 】

Volume Two: The War Against Extinction: Chapter 82 Do we really lack that sociology point?

They come quickly.

Less than a week has passed since the discussion on the "Beta aliens", and before they even held a seminar on the G2-139-da-L4-W wormhole, the "enemy" probes have already arrived.

Although people often accuse the United Nations of "wasting time in meetings when encountering anything", it is usually true, but at least this time, it is really not their turn to blame.

Because, in the assessment of the think tank, the other party has absolutely no reason to send the detector at this time.

Generally speaking, the purpose of a civilization sending probes to the other side of the wormhole is nothing more than two, either to investigate the condition of the galaxy, find out the distribution of its settlements, or try to communicate with the civilization on the other side of the wormhole—even most of the time , the detector does not need to have the ability to communicate directly with the local civilization.

As long as the probe flies over, let the locals realize that "there is a technological civilization on the opposite side of the wormhole" - as long as this is known, and the technology tree is not too crooked, the two technological civilizations can be achieved very quickly. communication.

Although going deeper, current humans still know almost nothing about the principle of wormholes "distorting" electromagnetic waves, but in many cases, it is not necessary to really understand its principle to use a thing.

It's as if human beings can't explain the principle of lift generation (the existing theories have loopholes, and there is no theory that can fully explain it), but this does not affect their design of more and more advanced aircraft-"black box theory" is The norm of modern science.

Although I don't know why it is this value, you can use it anyway.jpg

Even in many cases, during the actual operation of the project, I don't even bother to guess - anyway, according to experience, it is this value!

The same is true for the study of wormholes. Although there are few theories, as long as you try, you will soon find a suitable angle to listen to or send signals.

After completing the first proofreading, combined with the optical phenomena on the surface of the wormhole, the Doppler effect and other data, and calculating the position and orbital parameters of the target planet through appropriate algorithms, most of the success has been achieved.

Next, as long as the antenna can be aimed at the opponent's planet accurately according to the parameters, and the return signal of the opponent's cat and tiger is successfully received, the rest of the language deciphering link will become extremely simple-it is nothing more than the old data analysis. Even the earth before entering the interstellar era can do it.

Not to mention, this civilization tentatively named "Beta" successfully entered the G2-139-d orbit of the Iron Heart Exterminator a few days ago despite the battle damage to cover the satellite.

This satellite has already flown to the doorstep of the house, no matter how inaccurate the antenna is, it is still some kind of technological civilization-in this way, human beings naturally relax their vigilance when they know that the establishment of communication is a foregone conclusion.

To be precise, it is to give up the meaningless waste of resources-if there is no need to intercept the detector, it is more conducive to combat to move the front as a whole away from the wormhole and avoid the space distortion zone.

"So, you mean, that spaceship just rushed through the wormhole guarded by more than 30 battleships?"

However, the well-informed commander-in-chief naturally grasped the key points directly.

"...From the results, yes."

"Then I really wish you good health."

He "tactfully" blessed the captain on the other side of the phone-although they didn't make any mistakes in terms of procedure, at most it was a little "not thoughtful", but the captain at this time naturally Will not choose the head iron hard steel boss.

Anyway, the boss will have to go back to be scolded soon, everyone is scolded, why bother.

"Where is that detector now?"

Although the commander-in-chief knew that now they had lost the possibility of intercepting that spaceship—as long as they didn't stop it within the initial range of the fleet, it was almost impossible to catch up with the other party at a speed of 60 kilometers per second.

But I can't control it, I can't control it, and I still need to understand the information-at least, if I don't know anything when I report it later, I will be scolded even more severely.

"Moving towards the outer planet at a speed of 62.7 kilometers per second, the current orbital parameters are..."

The captain immediately reported the data - a hyperbolic orbit with an eccentricity greater than one.

Since its speed relative to the star has reached 90 kilometers per second, far exceeding the escape velocity of the star in this orbit of 43 kilometers per second, this means that the spacecraft will not enter the wormhole as usual The orbits of the planets it orbits, but directly into the vast space beyond the planetary system.

"Why does it feel a bit wrong..." He simulated the orbit on the computer casually, and said with some doubts, "Smith, don't you think this spaceship doesn't seem to know where it's flying at all?"

"......what?"

Obviously, Captain Smith didn't see it.

"Open the star map and have a look." After testing several parameters in the simulation program, the conductor confirmed his guess even more, "This orbit is out of the ecliptic plane, and it is very far from all the planets throughout the whole process."

"You mean..."

Although he didn't think of it at first, he seemed to have a feeling after the conductor said this.

"As long as the orbit is deflected a little bit, any one of G2-139-e or f can be passed by at a fairly suitable distance, and the information on it can be easily obtained."

Although he knew that the other party located more than 20 kilometers away could not see his screen, he still subconsciously pulled the screen to fully display the new trajectory simulated by the computer.

"Moreover, if there are enough DVs on it, you can also reconnaissance the two planets by changing orbits-this will not consume too much, a few kilometers per second is enough."

Looking at the complex star map composed of various lines in front of him, he touched his chin, and already had a guess in his mind.

He also needs a proof to prove it.

"Tell the Observation Department that I need them to track the real-time data on the orbit of the alien spacecraft code-named 'β039', especially the orbit change operation."

The commander briefly explained the mission, turned around and picked up the communication with Captain Smith: "Smith, upload back all the images about 'β039' captured by your sighting equipment."

"understand!"

Soon, after collecting all the relevant data, the experts made the same judgment as he expected after observing for a few minutes.

This spaceship is not the same civilization as the warships that had exchanged fire with them before!

"Most parts of this spaceship are obviously different from Beta Civilization." A scholar explained, "Especially here, look at this mechanical arm, its structure is the same as that of Beta Civilization's current orbiting G2-139- The design idea on d's moon is almost the exact opposite."

"And here, here, and here, are quite obvious differences in design."

"Normally speaking, there is no reason for a civilization to design two parts with exactly the same effect, but with completely different production standards and structures—even in the old earth era, the two camps would not specialize in such thankless things during the war. .”

The expert group gave the conclusion.

"This is likely to be the vehicle of two different civilizations."

"Understood, thank you for your analysis."

After the two sides were polite to each other, the commander stopped receiving the screen projection, and the conference room returned to silence.

"Two different civilizations..."

He pondered this sentence carefully and murmured to himself.

......

Soon, with the help of a professional team, through the ultra-high-definition imaging of the Starcastle 039-meter-class astronomical telescope, as well as the analysis of the attitude judgment and antenna pointing of "β[-]" when it first came out of the wormhole, the rear cake layer also confirmed that His guess.

In fact, after judging that it does not belong to the Beta civilization, it is no longer called "β039".

According to the naming habits of human beings, this brand-new unknown civilization was inherited sequentially and obtained the code name of "Gamma Civilization". Naturally, this spaceship also received the number "γ001" in sequence.

Yes, the gamma aliens - have the same code name as the "starfish" that blew up the Earth Federation colonies in a popular space SLG game that was remade twice.

Although this unlucky name was immediately complained by many people, but since no one in the cake layer played this game, they naturally didn't know the special meaning behind it.

"According to the current intelligence, we can already be sure that this Gamma civilization and the Beta civilization are in a state of hostility, at least in a state of cold war."

The scientist in charge of the Gamma Civilization Language Analysis Project stood in front of the big screen, holding a laptop in one hand and a pointer in the other.

"According to the detection of the detector passing through the G2-139-da-L4-W wormhole, we have now locked the position of the signal source of the Gamma civilization." He switched to this star map tentatively named "Beta Galaxy" , pointing to a red dot in the empty space between the giant planet and the inner ring planet, "the asteroid belt 2000 million kilometers from the wormhole."

"Are there no planets?"

"No."

Several senior officials looked at each other.

"Which party is developing the inner planet?"

"No one is developing, at least not on a large scale." The scholar clicked on the screen and switched to the photos of the two planets in the inner ring. Confirm the absence of any mass settlements on its surface."

"In other words, the two civilizations in this galaxy, one is in the giant planet satellite belt, and the other is in the asteroid belt?"

"So far, yes."

Even with the evidence of images, the scholar still did not give a definite answer—after all, the living environment of these two civilizations is beyond their imagination for human beings.

"This is really... incredible."

The deputy commander of the British and French Commonwealth sighed.

You must know that unlike the Pan-Asians who are mainly distributed on large planets such as the Earth, the Moon, and Mars, as the people of the British and French Commonwealth whose main stars are all Jupiter satellites, he has difficulty in living in the giant planetary satellite belt and asteroid belt. But I have a deep understanding.

Although due to the lower gravity, people living there can put cargo into orbit in a fairly cheap way, making the giant planet satellite belt the star field with the highest industrial potential in the entire solar system.

However, this does not conceal that it is one of the most harsh living environments in the main star region of human beings - the extreme low temperature brought by being far away from the sun, the ultra-high radiation brought by Jupiter's strong magnetic field, and the low temperature that is difficult for humans to adapt to. The gravity, the extreme lack of infrastructure, and the extremely long travel time with the inner ring planet all make this place a model of "difficult to survive".

This is not something that can explain the past with different life forms - even if the other party is not a carbon-based organism, as long as it still takes the laws of physics into account, it is impossible to avoid problems other than gravity and low temperature.

Although the industrial value of giant planets is really high, for a normal civilization, there is no need to give up the parent star that has been developed for thousands of years.

This is not a multiple-choice question, the two star fields can be developed together.

"According to the current survey and mapping, our team's judgment is that the creators of the 'Beta Civilization' should not have originated from a rocky planet like the Ironheart Exterminator or us, but more likely originated from a giant planet on a satellite."

"In this way, with the development of science and technology, they naturally occupied the entire satellite belt of the giant planet, and for some unknown reason, they did not choose to carry out large-scale development on other planets-this is the most likely guess, otherwise it cannot explain the contrast in development between the satellite belts of the giant planets and other planets."

"What about the Gamma civilization?"

The commander-in-chief of Pan Asia asked.

"Could they be the creators of the Beta civilization? They were driven to the asteroid belt after being rebelled by omnics?"

"This is indeed a possibility." The scientist nodded, "However, due to the small observation equipment of the detector, we have not been able to clearly image the signal source. We can only judge that there are objects with high reflectivity—and It is very large, a large object with a long axis of at least ten kilometers."

"Space City?"

"Starport?"

The people present randomly guessed a few based on their experience—although they didn't know which one it was, it must be some kind of giant man-made object.

Combined with the high-power signals captured there, this is pretty good news for humans.

It is known that the two sides are likely to be hostile to each other, combined with the news that the Beta civilization and the Iron Heart Exterminator are both omnic civilizations whose action program is to "destroy organic creatures", it can be easily judged that this Gamma civilization is very likely to be an organic civilization .

No matter what, even if the two sides do not form an alliance or even turn into hostility in the end, as long as it is still an organic civilization, then out of survival considerations, the other side will definitely take the initiative to start a war with the Beta civilization, thereby relieving the pressure on the human side.

What's more, judging from the current situation that the other party is trying every means to communicate with them, the other party's willingness to form an alliance may not be weak-obviously, this is a business that can make money without losing money.

"Increase manpower, be sure to decipher the signal as soon as possible, and get in touch with the other party!"

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