Throughout the twentieth century, science fiction writers wrote a lot and talentedly about space exploration. The heroes of "Chius" gave humanity the riches of Uranium Golconda, the pilot Pirx worked as a captain of space dry cargo ships, leader-container carriers and bulk carriers walked around the solar system, and I'm not talking about all the mysticism of travel to mysterious monoliths.
However, the 21st century has not lived up to expectations. Mankind timidly stands in the hallway of the Cosmos, not getting out on a permanent basis beyond the earth's orbit. Why did it happen and what to hope for those who would like to read in the news about increasing the yield of Martian apple trees?
No violinist needed
The first paradox we encountered is that humans are not the most suitable subject for space exploration. Science fiction writers who came up with space expeditions could only rely on the historical experience of the pioneers of the Earth - seafarers, polar explorers, the first aviators. Indeed, how would the conquest of Mars differ from the conquest of the South Pole?
And here and there the environment is unsuitable for life without preliminary preparation, you need to bring supplies with you, and you cannot go outside the ship or home without putting on special equipment. But science fiction writers and futurists could not predict the development of electronics and robotics, and robotic researchers were usually described in an anecdotal way:
“I had to look away from the letter for half an hour and listen to the complaints of my neighbor, cybernetist Shcherbakov. You probably know that a grand underground uranium and transuranide processing plant is under construction to the north of the rocket launcher. People work six shifts. Robots - around the clock; wonderful machines, the last word in practical cybernetics. But, as the Japanese say, the monkey also falls from the tree. Now Shcherbakov came to me, angry as the devil, and said that a gang of these mechanical idiots (his own words) stole one of the large ore depots tonight, mistaking it, obviously, for an unusually rich deposit. The robots had different programs, so by the morning part of the warehouse ended up in the warehouses of the rocket launcher, part at the entrance to the geological department, and part of it was generally unknown where. The search continues."
Promotional video:
But none of the famous authors guessed that a robot in space exploration has a lot of advantages over a person:
Unlike a human, a robot only needs power and thermal balance. There is no need to carry tens of tons of greenhouses, food, water, oxygen, clothing and hygiene products, medicines and other things with you.
The robot can be sent one way without returning.
The robot is capable of working for years. The experience of Voyagers, Mars rovers or Cassini suggests that now it is more correct to speak not about years, but decades.
The robot is capable of working for years in conditions that are fatal to humans. The Galileo probe received a dose 25 times higher than the lethal dose for humans and after that it 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 to satisfy scientific curiosity and get beautiful photographs.
We live in a logistic curve
The second mistake of science fiction writers was that they predicted linear or even exponential development of astronautics. Although back in 1838 such a phenomenon as the logistic curve was discovered. What is this terrible beast? Take aviation history as an example:
1900s. The first clumsy bookcases, the first records - flights for several kilometers with one passenger.
1910th. The first scouts, fighters, bombers, mail and passenger aircraft.
1920-1930s. Mastering flights at night, the first transcontinental flights.
1940s. Aviation is a serious military and transport force.
1950s. Jet engines give a new impetus to the development of aviation - new speeds, ranges and heights, and even more passengers.
1960-70s. The first supersonic and wide-body passenger aircraft, aviation is more affordable.
1980-90s. Braking. Development is becoming more and more expensive, development firms are uniting into giant companies. And the planes are more and more similar to each other.
2000s. Limit. The two giants, Boeing and Airbus, make outwardly identical machines, and supersonic passenger aircraft have died out altogether.
If you translate these achievements into numbers, you get the following picture:
In astronautics, the situation is exactly the same:
For clarity, the S-curve graph can be overlaid with a graph of costs to achieve this level:
And the sadness of our "today" is that in astronautics with existing technologies we are close to the saturation level. Technically, you can fly in a manned version to the Moon and even Mars, but somehow it's a pity for money.
Put KC - you will get gravity
The next sad aspect, slowing down the dash into space, is that something very valuable has not yet been discovered, for which it is worth spending money on space exploration beyond Earth's orbit. Please note that there are a lot of commercial satellites in near-earth orbit - communications, TV and the Internet, meteorological, cartographic ones. And they all have tangible, monetary benefits. And what is the use of a manned mission 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 a primary object, it is a terrestrial planet, with its evolution and internal structure, similar to the Earth.
The moon is ancient and keeps the history of the first billion years of evolution of the terrestrial planets.
The youngest lunar rocks are about the same age as the oldest earthly rocks. Traces of the earliest processes and events that may have influenced the Moon and the Earth can be found now only on the Moon.
The Moon and Earth are genetically related and formed from different proportions of a common set of materials.
The moon is lifeless and contains no living organisms or local organic matter.
Lunar rocks originated from high-temperature processes without the participation of water. They are classified into three types: basalts, anorthosites, and breccias.
Long ago, the Moon was molten to a great depth and formed an ocean of magma. The Lunar 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 huge asteroid impacts that formed pools filled with lava flows.
The moon is somewhat asymmetrical, possibly due to the influence of the Earth.
The surface of the moon is covered with rock pieces and dust. This is called lunar regolith and contains the Sun's unique radiative history, which is important for understanding climate change on Earth.
This is all very interesting (no jokes), but all this knowledge has an irreparable drawback - you cannot spread it on bread, pour it into a gas tank or build a house out of it. If a certain "elerium", "tiberium" or other shishdostanium were discovered in the vastness of space, which could be used as:
Cost effective energy source.
An integral part of the production of something valuable and useful.
Food / medicine / vitamin of a 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 mined by humans (so that cunning humanity would not send cheaper and more unpretentious robots), then it would be manned space exploration that would receive an invaluable incentive. And in the absence of him, in a pessimistic scenario in the 2020s, humanity may lose a permanent presence even in near-earth orbit - against the background of international cooperation pots broken by politicians, taxpayers may ask: "Why do we need a new station after the ISS?"
The curse of the Tsiolkovsky formula
Here it is, the nemesis of cosmonautics:
Here:
V is the final velocity of the rocket.
I - specific impulse of the engine (how many seconds the engine on 1 kilogram of fuel can create thrust 1 Newton)
M1 is the initial mass of the rocket.
M2 is the final mass of the rocket.
V for the case of full tanks will be the characteristic speed margin, i.e., the speed margin with which we can accelerate / decelerate if necessary. This is also called the delta-V margin (delta stands for change, i.e. it is the margin for the change in speed).
What is the problem here? Let's take a map of the required velocity changes for the solar system:
Let's imagine now that we want to fly to Mars and back. This will amount to:
9400 m / s - start from the Earth.
3210 m / s - leaving the Earth's orbit.
1060 m / s - interception of Mars.
0 m / s - entering the low orbit of Mars (white triangle means the possibility of braking against the atmosphere).
0 m / s - landing on Mars (we slow down on the atmosphere).
3800 m / s - start from Mars.
1440 m / s - acceleration from Mars orbit.
1060 m / s - Earth interception.
0 m / s - entering a low Earth orbit (we slow down against the atmosphere).
0 m / s - landing on the Earth (we slow down on the atmosphere).
The result is a beautiful figure of 19970 m / s, which we round up to 20,000 m / s. Let our rocket be ideal, and the volume of fuel does not affect its mass in any way (tanks, pipelines weigh nothing). Let's try to calculate the dependence of the initial mass of the rocket on the final mass and specific impulse. Transforming the Tsiolkovsky formula, we get:
M1 = eV / I * M2
Let's 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 the electric propulsion engine for today). I must say right away that for the maximum mass and minimum impulse there will be a very large value (22 million tons), so 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 for chemical engines. This is not news - on chemical engines, as practice perfectly shows, you can normally launch small probes, but even flying to the moon with a crew is already somewhat difficult.
Let's ease our conditions. First, let us assume that we are starting from the Earth's orbit, and instead of 20 km / s we need 10. Second, we cut off the "tail" of inefficient chemical engines, setting the minimum value of I to 4400 m / s (AI 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:
Let's give up completely from chemical engines. The NERVA nuclear engine had an AI of 9000 seconds. Let's recalculate:
[m2 I] = meshgrid (10: 50: 1000.9000: 5000: 200000);
m1 = exp (10000 * I. ^ - 1). * m2;
surf (m2, I, m1)
Linear scale:
Why am I repeating these monotonous graphs? The fact is that the flat area designated as "reason for optimism" shows that when engines with an AI of more than 50,000 m / s appear, it will become possible to fly more or less tolerably without ships with a starting mass of millions of tons within the solar system. And the electric propulsion engines, which are already in existence, have an ID of 25000-30000 m / s (for example, 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 engines have a small thrust, and in order to accelerate with a suitable acceleration, multi-megawatt reactors must be installed.
Let's build another interesting graph. Let us know the final mass - 1000 tons. Let us construct the dependence of the initial mass on the specific impulse and the final velocity:
[VI] = meshgrid (10000: 2000: 100000.50000: 5000: 200000);
m1 = exp (V. * (I. ^ - 1)) * 1000;
surf (V, I, m1)
This graph is interesting in that it is, in a sense, a look into the more distant future of humanity. If we want a comfortable and fast flight across the solar system, then we will have to go one order of magnitude higher in mastering the specific impulse - we need engines with an ID of several hundred thousand meters per second.
There are no fish here
Humanity is distinguished by cunning and ingenuity. Therefore, many ideas have been invented in order to facilitate access to space. One of the most important parameters characterizing the barrier that we want to jump over is the cost of putting a kilogram into orbit. Now, according to various estimates (this column has been removed from the Wiki, here, for example, another source) for various launch vehicles, this price is in the range of $ 4000- $ 13000 per kilogram for low-earth orbit. What did you try to come up with 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 Space Shuttle program. Now Elon Musk is doing this, planning to plant the first stage. I would like to wish him every success, but based on the past failure, I don't think this will be a qualitative breakthrough. In the best case, the cost will drop by a few percent.
Single Stage to Orbit. She did not go beyond the projects, despite repeated attempts.
Air start. There is a successful project for a small payload, but does not scale for heavy loads.
Rocketless space launch. A lot of projects have been invented, but all of them have a fatal drawback - astronomical investments are required, which cannot be "recaptured" without the complete completion of the project. Until the space elevator, fountain or mass driver is fully built and launched, there is no profit from it.
Than the heart will 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 as a whole is not one S-curve, but a lot of them, which forms such an optimistic picture:
In the history of aviation, one can distinguish, for example:
And, for sure, we are standing at a similar point in the development of cosmonautics. Yes, now there is some stagnation, and even a rollback is possible, but humanity, with the heads of its best representatives, breaks through the wall of knowledge, and somewhere, not yet noticed, the shoots of a new future are breaking through.
The second argument is the news about the development of a nuclear reactor for the transport-energy module, which is going without much fuss:
The latest news on this project was in the summer - the first TVEL was assembled. Work, albeit without regular publicity, is obviously going on, and one can hope for the appearance in the coming years of a fundamentally new apparatus - a nuclear tug with an electric propulsion engine.
P. S
These are somewhat unkempt thoughts, let's call them the first iteration. I would like to get feedback - maybe I missed something or incorrectly defined the significance of the phenomenon. Who knows, maybe after processing the feedback, you will get a more coherent concept or come up with something interesting?
Avor: lozga