Mistakes of science fiction writers or reflections on why astronautics stopped

All the twentieth century science fiction writers wrote a great deal about space exploration. Heroes of “Khius” presented humanity with the wealth of Golkonda's Uranium, the pilot Pirks worked as a captain of space cargo ships, the leader-carrier carriers and bulk carriers went through the Solar System, and I'm not talking about all mystic travels to mysterious monoliths. However, the 21st century did not meet expectations. Humanity is shyly standing in the hallway of the Cosmos, not permanently selected beyond the earth's orbit. Why did this happen and what should those who would like to read in the news about increasing the yield of Martian apple trees hope for?

Fiddler is not needed

The first paradox we have encountered is that man is not the most suitable subject for space exploration. Science fiction writers who invented space expeditions could rely only on the historical experience of the pioneers of the Earth — seafarers, polar explorers, and first aviators. Indeed, what, like, the conquest of Mars will be different from the conquest of the South Pole? Both there and there is unlivable environment without prior preparation, you need to carry supplies with you, and you cannot go outside the ship or at home without putting on special equipment. But science fiction writers and futurologists could not predict the development of electronics and robotics, and research robots were usually described in an anecdotal manner:

I had to leave the letter for half an hour and listen to the complaints of my neighbor, the cybernetist Shcherbakov. You probably know that a grandiose underground uranium and trans-uranium processing plant is under construction north of the rocket base. People work in six shifts. Robots - day and night; wonderful machines, the last word of practical cybernetics. But as the Japanese say, the monkey also falls from the tree. Now Shcherbakov came to me, angry as hell, and reported that a gang of these mechanical idiots (his own words) had stolen one of the large ore warehouses tonight, taking it, obviously, as an unusually rich deposit. The robots had different programs, so by morning a part of the warehouse was located in the warehouses of the launching base, some at the entrance to the geological department, and some of them are not known where. The search continues.

But none of the well-known authors guessed that the robot in space exploration has a lot of advantages over man:

• Unlike humans, a robot only needs power supply and thermal balance. Do not carry with you tens of tons of greenhouses, food, water, oxygen, clothing and hygiene products, medicines and other things.
• The robot can be sent one way, without returning.
• The robot is able to work for years. The experience of "Voyagers", rovers or "Cassini" suggests that now it is more correct to speak not about years, but decades.
• The robot is able to work for years in conditions that are deadly to humans. The probe "Galileo" received a dose of 25 times the lethal for a man and after that he worked in orbit for 8 years.

As a result, it turned out that only robots weighing several tons fit into the technical capabilities of mankind to send them to other planets for reasonable money and became the only way for today to satisfy scientific curiosity and get beautiful pictures.

We live in a logistic curve

The second mistake of science fiction writers was that they predicted a linear or even exponential development of cosmonautics. Although back in 1838, the phenomenon of the logistic curve was discovered. What is this terrible beast? For example, take the history of aviation:

• 1900s The first clumsy racks, the first records - flying for several kilometers with one passenger.
• 1910s The first scouts, fighters, bombers, mail and passenger aircraft.
• 1920-1930 Flight mastering at night, first transcontinental flights.
• 1940s Aviation is a serious military and transport force.
• 1950s Jet engines give new impetus to the development of aviation - new speeds, ranges and heights, and even more passengers.
• 1960-70e. The first supersonic and wide-body passenger airplanes, aviation is more accessible.
• 1980s-90s. Braking. Development is more expensive, development companies are combined into giant companies. And the planes are more and more similar to each other.
• 2000s Limit. Two giants "Boeing" and "Airbus" make outwardly identical cars, supersonic passenger planes have become extinct.

If you translate these achievements into numbers, you get this picture:
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In space, the situation is exactly the same:



For clarity, the S-curve graph can be superimposed on the expenditure schedule for achieving this level:



And the sadness of our “today” is that in cosmonautics on existing technologies we are close to saturation level. Technically, you can fly in a manned version to the moon and even Mars, but somehow you feel sorry for the money.

Put KC - you will get a gravitap

The next sad aspect, a braking breakthrough into space - until something very valuable has been discovered, for which it is worth spending money on space exploration beyond Earth's orbit. Please note that there are now a lot of commercial satellites in Earth orbit - communications, TV and the Internet, meteorological, cartographic. And they all have a tangible, money-expressed benefit. And what is the use of the manned program of flights to the moon? Here is the official list of the results of the US lunar program worth approximately $ 170 billion (in 2005 prices):

• The moon is not the primary object, it is a planet of the terrestrial group, with its evolution and internal structure, similar to the Earth.
• The moon is ancient and keeps the history of the first billion years of the evolution of the terrestrial planets.
• The youngest lunar rocks are about the same age as the most ancient terrestrial ones. Traces of the earliest processes and events that may have influenced the moon and the earth can now be found only on the moon.
• The moon and the Earth are genetically related and are formed from different proportions of a common set of materials.
• The moon is lifeless and does not contain living organisms or organic matter of local origin.
• Moon rocks originated from high-temperature processes without water. They are divided into three types: basalts, anorthosites and breccia.
• A long time ago, the Moon was melted to a great depth and formed an ocean of magma. The Moon Mountains contain remnants of early low-density rocks that floated on the surface of this ocean.
• The ocean of magma was formed by a series of blows from huge asteroids that formed pools filled with lava flows.
• The moon is somewhat asymmetric, possibly due to the influence of the earth.
• The surface of the moon is covered with pieces of rock and dust. This is called the lunar regolith and contains a unique radiation history of the Sun, which is important for understanding climate change on Earth.

This is all very interesting (no jokes), but all this knowledge has an irreparable disadvantage - they cannot be spread on bread, poured into a gas tank or built a house from them. If in the vastness of the cosmos a certain “Elerium”, “Tiberium” or another Shishdostanium would be found that could be used as:

• An economical source of energy.
• An integral element of the production of something valuable and necessary.
• Food / medicine / vitamin fundamentally new quality.
• A luxury item or source of pleasure.

If it also grew only on Mars or in the asteroid belt (and was not reproduced on Earth) and could only be obtained by man (so that cunning humanity would not send cheaper and unpretentious robots), then it would be manned space exploration that would receive invaluable stimulus. And in the absence of it in the pessimistic scenario in the 2020s, mankind may lose its permanent presence even in near-earth orbit - against the backdrop of pots of international cooperation beaten by politicians, taxpayers may ask: “Why do we need a new station after the ISS?”

Curse of Tsiolkovsky formula

Here it is, nemesis of astronautics:


Here:

• V - the final speed of the rocket.
• I is the specific impulse of the engine (how many seconds the engine can generate 1 Newton thrust on 1 kilogram of fuel)
• M ₁ - the initial mass of the rocket.
• M ₂ - the final mass of the rocket.

V for the case of full tanks will be the margin of the characteristic speed, i.e., the margin of speed by which we can accelerate / decelerate if necessary. This is also called the delta-V margin (delta means a change, i.e. it is a speed change stock).

What is the problem here? Take the metro map map of the required changes in speed for the solar system ( big picture ):



Imagine now that we want to fly to Mars and back. This will be:

1. 9400 m / s - start from the Earth.
2. 3210 m / s - departure from the orbit of the Earth.
3. 1060 m / s - interception of Mars.
4. 0 m / s - the exit to the low orbit of Mars (a white triangle means the possibility of braking about the atmosphere).
5. 0 m / s - landing on Mars (we brake about the atmosphere).
6. 3800 m / s - start from Mars.
7. 1440 m / s - acceleration from the orbit of Mars.
8. 1060 m / s - Earth interception.
9. 0 m / s - an exit to a low orbit of the Earth (we brake about the atmosphere).
10. 0 m / s - landing on Earth (we brake about the atmosphere).

The result is a beautiful figure of 19970 m / s , which we round up to 20 000 m / s . Let the rocket be perfect, and the volume of fuel does not affect its mass in any way (tanks, pipelines do not weigh anything). Let's try to calculate the dependence of the initial mass of the rocket on the final mass and specific impulse. Transforming the formula Tsiolkovsky, we get:
M ₁ = e ^{V / I} * M ₂
We use the free mathematical package Scilab. We take the final mass in the range of 10-1000 tons, the specific impulse will vary from 2000 m / s (chemical engines on hydrazine) to 200 000 m / s ( theoretical estimate of the maximum impulse of electric propulsion for today). At once I will say that for the maximum mass and the minimum impulse there will be a very large value ( 22 million tons ), therefore the display scale will be logarithmic.

  [m2 I] = meshgrid (10: 50: 1000,2000: 5000: 200000);
 m1 = log (exp (20000 * I. ^ - 1). * m2);
 surf (m2, i, m1) 

This beautiful graph is, in fact, a visual verdict to chemical engines. This is not news - on chemical engines, as practice shows, it is possible to launch small probes normally, but even flying to the moon with the crew is already somewhat difficult.

Relieve the conditions. First, let us assume that we are launching from the orbit of the Earth, and instead of 20 km / s we need 10. Secondly, we cut off the “tail” of inefficient chemical engines, setting the minimum value of I 4400 m / s (UI of the Space Shuttle hydrogen engine RS-25 ):

  [m2 I] = meshgrid (10: 50: 1000.4400: 5000: 200000);
 m1 = log (exp (10000 * I. ^ - 1). * m2);
 surf (m2, i, m1) 

Logarithmic scale:


Linear scale:


We give up completely from chemical engines. The nuclear engine NERVA had an UI of 9000 seconds. We will recalculate:

  [m2 I] = meshgrid (10: 50: 1000.9000: 5000: 200000);
 m1 = exp (10000 * I. ^ - 1). * m2;
 surf (m2, i, m1) 

Linear scale:



Why do I repeat these monotonous graphics? The fact is that a flat area designated as “a reason for optimism” shows that when engines with an ID of more than 50,000 m / s appear, it will be possible to more or less tolerably fly millions of tons within ships within the Solar System. And ERD, which is already now, have an IU of 25000-30000 m / s ( for example, the SPD 2300 ).
However, it is necessary to understand that the reason for optimism is very restrained. First, these thousands of tons must be delivered to Earth's orbit (which is extremely difficult). Secondly, the existing electric propulsion has a small thrust, and in order to accelerate with a suitable acceleration, it is necessary to install multi-megawatt reactors.

Construct another interesting schedule. Let us know the final weight - 1000 tons. Let us construct the dependence of the initial mass on the specific impulse and final velocity:

  [Vi] = meshgrid (10,000: 2,000: 10,000,000,000: 5,000: 2,000,000);
 m1 = exp (V. * (I. ^ - 1)) * 1000;
 surf (V, I, m1) 

This chart is interesting because it is in a sense a look into the more distant future of mankind. If we want a comfortable and fast flight through the Solar System, then we will have to go even higher in the development of the specific impulse - engines with an MD of several hundred thousand meters per second will be needed.

There is no fish

Humanity is distinguished by cunning and ingenuity. Therefore, many ideas were invented in order to facilitate access to space. One of the most important parameters characterizing the barrier that we want to jump is the price of putting a kilogram into orbit. Now, according to various estimates (this column was removed from Wiki, for example, another source ) for various launch vehicles, this price is in the range of $ 4000- $ 13000 per kilogram to a low near-earth orbit. What were you trying to think of in order to make it easier, easier and cheaper to get at least into near-earth orbit?

• Reusable systems. Historically, this idea has already failed once in the program "Space Shuttle". Now Elon Musk, who plans to plant the first stage, is doing this. I would like to wish him every success, but on the basis of the past failure I do not think that this will be a qualitative breakthrough. At best, the cost will fall by a few percent.
• Single Stage to Orbit. Not overstepped projects , despite repeated attempts.
• Air start. There is a successful project for a small payload, but does not scale for heavy loads.
• Space free launch . A lot of projects have been invented, but all of them have a fatal flaw - astronomical investments are required, which cannot be “recaptured” without complete completion of the project. While the space elevator, fountain or mass driver will not be fully built and launched, there is no profit from it.

How does the heart calm down

How can you cheer up after these sad reflections? I have two arguments - one abstract and fundamental, the other more specific.
Firstly, progress in general is not one S-curve, but a multitude of them, which forms just such an optimistic picture:



In the history of aviation can be identified, for example:



And, for sure, we are standing at a similar point in the development of astronautics. Yes, some stagnation is now observed, and even a rollback is possible, but humanity is breaking through the walls of knowledge with the heads of its best representatives, and somewhere, not yet seen, the shoots of a new future are breaking through.

The second argument is the news about the development of an atomic reactor for the transport and energy module:



The latest news on this project was in the summer - they collected the first TVEL . The work, albeit without regular publicity, is obviously being continued, and one can hope for the emergence in the coming years of a fundamentally new apparatus - a nuclear tug with an electric propulsion.

P.S

These are somewhat unkempt thoughts, let's call them the first iteration. I would like to get feedback - maybe I missed or incorrectly determined the significance of the phenomenon. Who knows, maybe after processing the feedback, a more slim concept will come out or something interesting will be invented?

KDPV from here . Illustrations of S-curves from old LJ by Alexey Anpilogov .