The solar system has not been of particular interest to science fiction writers for a long time. But, surprisingly, our “native” planets do not cause much inspiration for some scientists, although they have not yet been practically explored.

Having barely cut a window into space, humanity is torn into unknown distances, and not only in dreams, as before.
Sergei Korolev also promised to soon fly into space "on a trade union ticket", but this phrase is already half a century old, and a space odyssey is still the lot of the elite - too expensive. However, two years ago, HACA launched a grandiose project 100 Year Starship, which involves the gradual and long-term creation of a scientific and technical foundation for space flights.

This unprecedented program should attract scientists, engineers and enthusiasts from all over the world. If everything is successful, in 100 years humanity will be able to build an interstellar ship, and we will move around the solar system like trams.

So what are the problems that need to be solved to make stellar flight a reality?

TIME AND SPEED ARE RELATIVE

Strange as it may seem, the astronomy of automatic vehicles seems to some scientists to be an almost solved problem. And this despite the fact that there is absolutely no point in launching automata to the stars with current snail speeds (about 17 km / s) and other primitive (for such unknown roads) equipment.

Now beyond solar system the American spacecraft Pioneer 10 and Voyager 1 left, there is no longer any connection with them. Pioneer 10 is moving towards the star Aldebaran. If nothing happens to him, he will reach the vicinity of this star ... in 2 million years. In the same way crawl across the expanses of the Universe and other devices.

So, regardless of whether a ship is inhabited or not, in order to fly to the stars, it needs high speed close to the speed of light. However, this will help solve the problem of flying only to the nearest stars.

“Even if we managed to build a star ship that could fly at a speed close to the speed of light,” K. Feoktistov wrote, “the travel time only in our Galaxy will be calculated in millennia and tens of millennia, since its diameter is about 100,000 light years. But on Earth, for this time will pass a lot more".

According to the theory of relativity, the course of time in two systems moving relative to one another is different. Since at large distances the ship will have time to develop a speed very close to the speed of light, the difference in time on Earth and on the ship will be especially large.

It is assumed that the first goal of interstellar flights will be alpha Centauri (a system of three stars) - the closest to us. At the speed of light, you can fly there in 4.5 years, on Earth ten years will pass during this time. But the greater the distance, the greater the difference in time.

Remember the famous Andromeda Nebula by Ivan Efremov? There, flight is measured in years, and earthly ones. A beautiful story, to say the least. However, this coveted nebula (more precisely, the Andromeda galaxy) is located at a distance of 2.5 million light years from us.

According to some calculations, the astronauts' journey will take more than 60 years (according to starship hours), but an entire era will pass on Earth. How will the space "Neanderthals" be met by their distant descendants? And will the Earth be alive at all? That is, the return is basically meaningless. However, like the flight itself: we must remember that we see the Andromeda galaxy as it was 2.5 million years ago - so much of its light reaches us. What is the point of flying to an unknown target, which, perhaps, has not existed for a long time, in any case, in its former form and in the old place?

This means that even flights at the speed of light are justified only up to relatively close stars. However, vehicles flying at the speed of light, so far live only in a theory that resembles science fiction, however, scientific.

A SHIP THE SIZE OF A PLANET

Naturally, first of all, scientists came up with the idea to use the most efficient thermonuclear reaction in the ship's engine - as already partially mastered (for military purposes). However, to travel in both directions at a speed close to the speed of light, even with an ideal design of the system, the ratio of the initial mass to the final mass is not less than 10 to the thirtieth power. That is, the spaceship will look like a huge train with fuel the size of a small planet. It is impossible to launch such a colossus into space from Earth. Yes, and collect in orbit - too, it is not for nothing that scientists do not discuss this option.

The idea of a photon engine using the principle of matter annihilation is very popular.

Annihilation is the transformation of a particle and an antiparticle during their collision into any other particles that are different from the original ones. The most studied is the annihilation of an electron and a positron, which generates photons, the energy of which will move the spaceship. Calculations by American physicists Ronan Keane and Wei-ming Zhang show that, based on modern technologies, it is possible to create an annihilation engine capable of accelerating a spacecraft to 70% of the speed of light.

However, further problems begin. Unfortunately, using antimatter as a rocket fuel is very difficult. During annihilation, flashes of the most powerful gamma radiation occur, which are detrimental to astronauts. In addition, the contact of positron fuel with the ship is fraught with a fatal explosion. Finally, there are no technologies yet to obtain enough antimatter and store it for a long time: for example, an antihydrogen atom "lives" now for less than 20 minutes, and the production of a milligram of positrons costs $25 million.

But, let's assume, over time, these problems can be resolved. However, a lot of fuel will still be needed, and the starting mass of a photon starship will be comparable to the mass of the Moon (according to Konstantin Feoktistov).

BROKEN THE SAIL!

The most popular and realistic starship today is considered to be a solar sailboat, the idea of which belongs to the Soviet scientist Friedrich Zander.

A solar (light, photon) sail is a device that uses the pressure of sunlight or a laser on a mirror surface to propel a spacecraft.
In 1985, the American physicist Robert Forward proposed the design of an interstellar probe accelerated by microwave energy. The project envisaged that the probe would reach the nearest stars in 21 years.

At the XXXVI International Astronomical Congress, a project was proposed for a laser spacecraft, the movement of which is provided by the energy of optical lasers located in orbit around Mercury. According to calculations, the path of a starship of this design to the star Epsilon Eridani (10.8 light years) and back would take 51 years.

“It is unlikely that we will be able to make significant progress in understanding the world in which we live, based on data obtained from travels in our solar system. Naturally, thought turns to the stars. After all, earlier it was understood that flights around the Earth, flights to other planets of our solar system are not the ultimate goal. To pave the way to the stars seemed to be the main task.
These words do not belong to a science fiction writer, but to the spacecraft designer and cosmonaut Konstantin Feoktistov. According to the scientist, nothing particularly new in the solar system will be found. And this despite the fact that man has so far only flown to the moon ...

However, outside the solar system, the pressure of sunlight will approach zero. Therefore, there is a project to accelerate a solar sailboat with laser systems from some asteroid.

All this is still theory, but the first steps are already being taken.

In 1993, a 20-meter-wide solar sail was deployed for the first time on the Russian ship Progress M-15 as part of the Znamya-2 project. When docking the Progress with the Mir station, its crew installed a reflector deployment unit on board the Progress. As a result, the reflector created a bright spot 5 km wide, which passed through Europe to Russia at a speed of 8 km/s. The patch of light had a luminosity roughly equivalent to that of the full moon.

So, the advantage of a solar sailboat is the lack of fuel on board, the disadvantages are the vulnerability of the sail design: in fact, it is a thin foil stretched over a frame. Where is the guarantee that the sail will not get holes from cosmic particles along the way?

The sail version may be suitable for launching robotic probes, stations and cargo ships, but is unsuitable for manned return flights. There are other starship designs, but they somehow resemble the above (with the same massive problems).

SURPRISES IN INTERSTELLAR SPACE

It seems that many surprises await travelers in the Universe. For example, just leaning out of the solar system, the American device Pioneer 10 began to experience a force of unknown origin, causing weak deceleration. Many suggestions have been made, up to yet unknown effects of inertia or even time. There is still no unambiguous explanation for this phenomenon, a variety of hypotheses are considered: from simple technical ones (for example, the reactive force from a gas leak in an apparatus) to the introduction of new physical laws.

Another spacecraft, Voyager 1, detected an area at the edge of the solar system with a strong magnetic field. In it, the pressure of charged particles from interstellar space causes the field created by the Sun to thicken. The device also registered:

an increase in the number of high-energy electrons (about 100 times) that penetrate into the solar system from interstellar space;
a sharp increase in the level of galactic cosmic rays - high-energy charged particles of interstellar origin.

And that's just a drop in the ocean! However, even what is known today about the interstellar ocean is enough to cast doubt on the very possibility of surf the universe.

The space between the stars is not empty. Everywhere there are remnants of gas, dust, particles. When trying to move at a speed close to the speed of light, each atom colliding with the ship will be like a particle of high-energy cosmic rays. The level of hard radiation during such a bombardment will increase unacceptably even during flights to the nearest stars.

And the mechanical impact of particles at such speeds will be likened to explosive bullets. According to some calculations, every centimeter of the starship's protective screen would be fired continuously at a rate of 12 shots per minute. It is clear that no screen can withstand such exposure for several years of flight. Or it will have to have an unacceptable thickness (tens and hundreds of meters) and mass (hundreds of thousands of tons).

Actually, then the starship will consist mainly of this screen and fuel, which will require several million tons. Due to these circumstances, flights at such speeds are impossible, all the more so because along the way you can run into not only dust, but also something larger, or get trapped in an unknown gravitational field. And then death is inevitable again. Thus, even if it is possible to accelerate the spacecraft to subluminal speed, then it will not reach the final goal - there will be too many obstacles on its way. Therefore, interstellar flights can only be carried out at significantly lower speeds. But then the time factor makes these flights meaningless.

It turns out that it is impossible to solve the problem of transporting material bodies over galactic distances at speeds close to the speed of light. It makes no sense to break through space and time with the help of a mechanical structure.

MOLE HOLE

Science fiction, trying to overcome the inexorable time, invented how to "gnaw holes" in space (and time) and "fold" it. They came up with a variety of hyperspace jumps from one point of space to another, bypassing intermediate areas. Now scientists have joined science fiction writers.

Physicists began to look for extreme states of matter and exotic loopholes in the universe, where you can move at a superluminal speed contrary to Einstein's theory of relativity.

This is how the idea of the wormhole was born. This burrow links the two parts of the Universe like a carved tunnel connecting two cities separated by a high mountain. Unfortunately, wormholes are only possible in absolute vacuum. In our universe, these burrows are extremely unstable: they can simply collapse before a spaceship gets there.

However, to create stable wormholes, you can use the effect discovered by the Dutchman Hendrik Casimir. It consists in the mutual attraction of conducting uncharged bodies under the action of quantum oscillations in a vacuum. It turns out that the vacuum is not completely empty, there are fluctuations in the gravitational field in which particles and microscopic wormholes spontaneously appear and disappear.

It remains only to find one of the holes and stretch it, placing it between two superconducting balls. One mouth of the wormhole will remain on Earth, the other will be moved by the spacecraft at near-light speed to the star - the final object. That is, the spaceship will, as it were, punch through a tunnel. Once the starship reaches its destination, the wormhole will open up for real lightning-fast interstellar travel, the duration of which will be calculated in minutes.

WARP BUBBLE

Akin to the theory of wormholes bubble curvature. In 1994, Mexican physicist Miguel Alcubierre performed calculations according to Einstein's equations and found the theoretical possibility of wave deformation of the spatial continuum. In this case, the space will shrink in front of the spacecraft and simultaneously expand behind it. The starship, as it were, is placed in a bubble of curvature, capable of moving at an unlimited speed. The genius of the idea is that the spacecraft rests in a bubble of curvature, and the laws of the theory of relativity are not violated. At the same time, the bubble of curvature itself moves, locally distorting space-time.

Despite the impossibility of traveling faster than light, nothing prevents space from moving or propagating the warp of space-time faster than light, which is believed to have happened immediately after the Big Bang at the formation of the Universe.

All these ideas do not yet fit into the framework of modern science, but in 2012, NASA representatives announced the preparation of an experimental test of the theory of Dr. Alcubierre. Who knows, maybe Einstein's theory of relativity will someday become part of a new global theory. After all, the process of learning is endless. So, one day we will be able to break through the thorns to the stars.

Irina GROMOVA

In our Galaxy alone, the distances between star systems are unimaginably huge. If aliens from outer space really visit the Earth, the level of their technical development should be a hundred times higher than the current level of our earthly one.

A few light years away

To denote the distances between stars, astronomers introduced the concept of "light year". The speed of light is the fastest in the universe: 300,000 km/s!

The width of our Galaxy is 100,000 light years. To cover such a huge distance, aliens from other planets need to build a spaceship, the speed of which is equal to or even exceeds the speed of light.

Scientists believe that a material object cannot move faster than the speed of light. However, earlier they believed that it was impossible to develop supersonic speed, but in 1947 the Bell X-1 model aircraft successfully broke the sound barrier.

Perhaps in the future, when humanity has accumulated more knowledge about the physical laws of the universe, earthlings will be able to build a spaceship that will move at the speed of light and even faster.

Great Journeys

Even if aliens are able to move through space at the speed of light, such a journey should take many years. For earthlings, whose average life expectancy is 80 years, this would be impossible. However, each species of living beings has its own life cycle. For example, in California, USA, there are bristlecone pines that are already 5,000 years old.

Who knows how long aliens live? Maybe several thousand? Then interstellar flights lasting hundreds of years are common for them.

Shortcuts

It is likely that aliens have found shortcuts through outer space - gravitational "holes", or distortions of space formed by gravity. Such places in the universe could become a kind of bridges - shortcuts between celestial bodies located at different ends of the universe.

Categories

- . In other words, a horoscope is an astrological chart drawn up taking into account the place and time, taking into account the position of the planets relative to the horizon line. To build an individual natal horoscope, it is necessary to know the time and place of birth of a person with maximum accuracy. This is required in order to find out how the celestial bodies were located at a given time and in this place. The ecliptic in the horoscope is depicted as a circle divided into 12 sectors (zodiac signs. Turning to natal astrology, you can better understand yourself and others. The horoscope is a tool for self-knowledge. With its help, you can not only explore your own potential, but also understand relationships with others and even make some important decisions."> Horoscope127
. With their help, they find out the answers to specific questions and predict the future. You can find out the future by dominoes, this is one of the very rare types of fortune telling. They also guess on tea and coffee grounds, on the palm of your hand, and on the Chinese Book of Changes. Each of these methods is aimed at predicting the future. If you want to know what awaits you in the near future, choose the fortune-telling that you like best. But remember: no matter what events are predicted for you, take them not as an indisputable truth, but as a warning. Using divination, you predict your fate, but with some effort, you can change it."> Divination65

Can interstellar travel go from a pipe dream to a real possibility?

Scientists around the world say that humanity is moving further and further in space exploration, new discoveries and technologies are appearing. However, people still only dream of interstellar flights. But is this dream so unattainable and unrealistic? What does humanity have today and what are the prospects for the future?

According to experts, if progress does not stop in place, then within one or two centuries, humanity will be able to fulfill its dream. The super-powerful Kepler telescope at one time allowed astronomers to detect 54 exoplanets where the development of life is possible, and today the existence of 1028 such planets has already been confirmed. These planets, orbiting a star outside the solar system, are at such a distance from the central star that it is possible to maintain liquid water on their surface.

However, it is still impossible to get an answer to the main question - is humanity alone in the Universe - because of the gigantic distances to the nearest planetary systems. Many exoplanets, at a distance of a hundred or less light years from Earth, as well as a huge scientific interest, which they cause, make us look at the idea of interstellar travel in a completely different way.

Travel to other planets will depend on the development of new technologies and the choice of method that is necessary to achieve such a distant goal. For now, the choice has not yet been made.

In order for earthlings to be able to overcome incredibly huge space distances, and in a relatively short time, engineers and cosmologists will have to create a fundamentally new engine. It is too early to talk about intergalactic flights, but humanity could explore the Milky Way, the galaxy in which the Earth and the Solar System are located.

The Milky Way galaxy has about 200 - 400 billion stars, around which the planets move in their orbits. Closest to the Sun is a star called Alpha Centauri. The distance to it is about forty trillion kilometers or 4.3 light years.

A rocket with a conventional engine will have to fly to it for about 40 thousand years! Using the Tsiolkovsky formula, it is easy to calculate that in order to accelerate a spacecraft with a jet engine on rocket fuel to a speed of 10% of the speed of light, more fuel is needed than is available on the entire Earth. Therefore, to talk about a space mission with modern technologies, this is complete absurdity.

According to scientists, future space starships will be able to fly using a thermonuclear rocket engine. The fusion reaction makes it possible to produce energy per unit mass, on average, almost a million times more than with chemical process combustion.

That is why in the 1970s, a group of engineers, together with scientists, developed a project for a giant interstellar ship with a thermonuclear propulsion system. The unmanned spaceship Daedalus was supposed to be equipped with a pulsed thermonuclear engine. Small pellets were to be thrown into the combustion chamber and ignited by beams of powerful electron beams. Plasma, as a product of a thermonuclear reaction, flying out of the engine nozzle, gives traction to the ship.

It was assumed that Daedalus was supposed to fly to the star of Barnard, the path to which is six light years. The largest spaceship would have reached it in 50 years. And although the project was not implemented, to this day there is no more real technical project.

Another direction in the technology of creating interstellar spacecraft is the solar sail. The use of a solar sail is considered today as the most promising and realistic version of a starship. The advantage of a solar sailer is that it does not need fuel on board, which means that the payload will be much higher compared to other spacecraft. Already today there is a possibility of building an interstellar probe, where the pressure of the solar wind will be the main source of energy for the ship.

The seriousness of the intentions of developing interplanetary flights is evidenced by the project, which has been developed since 2010 in one of the main scientific laboratories of NASA. Scientists are working on a project to prepare a manned flight to other star systems over the next hundred years.

In the process of layout, case numbers and typos in formulas were corrected. Shown in a readable table format.
Ivan Alexandrovich Korznikov
Realities of interstellar flights

People have long dreamed of flying through outer space to other stars, traveling to other worlds and meeting with unearthly intelligence. Fantasists wrote mountains of paper, trying to imagine how this would happen, they invented a variety of techniques that could make these dreams come true. But for now, it's just a fantasy. Let's try to imagine how such a flight might look like in reality.
The distances between stars are so great that light from one star to another travels for years, and it travels at a very high speed. With =299 793 458 m/s. To measure these distances, astronomers use a special unit - a light year, it is equal to the distance that light travels in 1 year: 1 St. year = 9.46 10 15 meters (approx. 600 times the size of the solar system). Astronomers have calculated that in a sphere with a radius 21.2 light years around the sun 100 stars included in 72 stellar systems (double, triple, etc. systems of nearby stars). From here it is easy to find that, on average, one star system accounts for the volume of space 539 cubic light years, and the average distance between star systems is approximately 8.13 light years. The real distance may be less - for example, to the star closest to the Sun, Proxima Centauri 4.35 St. l, but in any case, an interstellar flight is a distance of at least a few light years. And this means that the speed of the starship must be no less than 0.1 c - then the flight will take several decades and can be carried out by one generation of astronauts.
Thus, the speed of the starship must be greater 30 000 km/s. For terrestrial technology, this is still an unattainable value - we have barely mastered speeds a thousand times less. But let us assume that all technical problems have been solved, and our starship has an engine (photonic or whatever) capable of accelerating the spacecraft to such speeds. We are not interested in the details of its structure and functioning, only one circumstance is important for us here: modern science knows only one way of acceleration in outer space - jet propulsion, which is based on the implementation of the law of conservation of momentum of a system of bodies. And what is important here is that with such a movement, the starship (and any other body) moves in space, physically interacting with everything that is in it.
Fantasists in their fantasies came up with various "hyperspace jumps" and "subspace transitions" from one point of space to another, bypassing intermediate areas of space, but all this, according to modern science, has no chance of being realized in reality. Modern science has firmly established that certain conservation laws are observed in nature: the law of conservation of momentum, energy, charge, etc. And with a "hyperspace jump" it turns out that in a certain region of space, energy, momentum and charges of a physical body simply disappear, that is these laws are not enforced. From the point of view of modern science, this means that such a process cannot be carried out. And most importantly - it is not clear what it is at all, it is a "hyperspace" or "subspace", once in which, the physical body ceases to interact with bodies in real space. V real world there is only something that manifests itself in interaction with other bodies (in fact, space is the relation of existing bodies), and this means that such a body will actually cease to exist - with all the ensuing consequences. So all this is a fruitless fantasy that cannot be the subject of serious discussion.
So, let's assume that the existing jet engine accelerated the spaceship to the sublight speed we need, and it moves with this speed in outer space from one star to another. Some aspects of such a flight have been discussed by scientists for a long time (, ), but they mainly consider various relativistic effects of such a movement, not paying attention to other significant aspects of interstellar flight. And the reality is that outer space is not an absolute void, it is a physical environment, which is commonly called the interstellar medium. It contains atoms, molecules, dust particles and other physical bodies. And with all these bodies, the starship will have to physically interact, which becomes a problem when moving at such speeds. Let's consider this problem in more detail.
Astronomers, observing radio emission from the cosmic environment and the passage of light through it, found that there are atoms and molecules of gases in outer space: mainly hydrogen atoms H , hydrogen molecules H 2 (there are about the same number of them as atoms H ), helium atoms Not (them in 6 times smaller than atoms H ), and atoms of other elements (most of all carbon C, oxygen O and nitrogen N ), which add up to about 1 % of all atoms. Even such complex molecules as CO 2, CH 4, HCN, H 2 O, NH 3, HCOOH and others, but in scanty quantities (there are billions of times fewer than atoms H ). The concentration of interstellar gas is very low and amounts (far from gas and dust clouds) on average 0,5-0,7 atoms on 1 cm 3.
It is clear that when a spaceship moves in such an environment, this interstellar gas will resist, slowing down the spaceship and destroying its shells. Therefore, it was proposed to turn harm into favor and create a ramjet engine, which, by collecting interstellar gas (and it is on 94 % consists of hydrogen) and annihilating it with the stocks of antimatter on board, would thus receive energy for the movement of the starship. According to the project of the authors, there should be an ionizing source ahead of the starship (creating an electron or photon beam that ionizes incoming atoms) and a magnetic coil that focuses the resulting protons to the axis of the starship, where they are used to create a photon jet.
Unfortunately, upon closer examination, it turns out that this project is not feasible. First of all, an ionizing beam cannot be electronic (as the authors insist) for the simple reason that a starship emitting electrons will itself be charged with a positive charge, and sooner or later the fields created by this charge will disrupt the operation of the starship's systems. If, however, a photon beam is used, then (however, as for an electron beam), the matter rests on a small photoionization cross section of atoms. The problem is that the probability of an atom being ionized by a photon is very small (so the air is not ionized by powerful laser beams). Quantitatively, it is expressed by the ionization cross section, which is numerically equal to the ratio of the number of ionized atoms to the photon flux density (the number of incident photons per 1 cm 2 per second). Photoionization of hydrogen atoms begins at the photon energy 13.6 electronvolt= 2.18 10 -18 J (wavelength 91.2 nm), and at this energy the photoionization cross section is maximum and equal to 6.3 10 -18 cm 2 (, p. 410). This means that for the ionization of one hydrogen atom it takes on average 1.6 10 17 photons per cm2 per second. Therefore, the power of such an ionizing beam must be gigantic: if the spaceship moves at a speed v then for 1 second per 1 cm 2 of its surface rv counter atoms, where r is the concentration of atoms, which in our case of near-light motion will be of the order of rv=0.7 3 10 10 =2 10 10 atoms per second 1 cm 2. This means that the flux of ionizing photons must be at least n= 2 10 10 / 6.3 10 -18 = 3 10 27 1/cm 2 s. The energy carried by such a photon flux will be equal to e\u003d 2.18 10 -18 3 10 27 \u003d 6.5 10 9 J / cm 2 s.
In addition, in addition to hydrogen atoms, the same number of molecules will fly into the starship H 2 , and their ionization occurs at photon energy 15.4 ev (wavelength 80.4 nm). This will require approximately a doubling of the flow rate, and the total flow rate should be e=1.3 10 10 J / cm 2. For comparison, we can point out that the photon energy flux on the surface of the Sun is equal to 6.2 10 3 J/cm 2 s, that is, the spacecraft must shine two million times brighter than the Sun.
Since the energy and momentum of a photon are related by the relation E=pc , then this photon flux will have momentum p=es/s where S - mass intake area (about 1000 m 2), which will be 1.3 10 10 10 7 / 3 10 8 =4.3 10 8 Kg m/s, and this impulse is directed against the speed and slows down the spaceship. In fact, it turns out that a photon engine is standing in front of the starship and pushing it in the opposite direction - it is clear that such a push-pull will not fly far.
Thus, the ionization of incident particles is too expensive, and modern science does not know any other way to concentrate interstellar gases. But even if such a method is found, the ramjet engine will still not justify itself: even Zenger showed (, p. 112) that the thrust of a ramjet photonic jet engine is negligible and it cannot be used to accelerate a rocket with high acceleration. Indeed, the total mass influx of incident particles (mainly hydrogen atoms and molecules) will be dm=3m p Srv\u003d 3 1.67 10 -27 10 7 2 10 10 \u003d 10 -9 kg/s. During annihilation, this mass will emit a maximum W=mc 2 = 9 10 7 J / s, and if all this energy is spent on the formation of a photon jet, then the increase in the momentum of the starship per second will be dr=W/c\u003d 9 10 7 / 3 10 8 \u003d 0.3 kg m/s, which corresponds to thrust in 0.3 newton. Approximately with such force a small mouse presses on the ground, and it turns out that the mountain gave birth to a mouse. Therefore, the design of ramjet engines for interstellar flights does not make sense.

From what has been said, it follows that it will not be possible to deflect the incoming particles of the interstellar medium, and the starship will have to receive them with its hull. This leads to some requirements for the design of the starship: in front of it there must be a screen (for example, in the form of a conical cover), which will protect the main body from the effects of cosmic particles and radiation. And behind the screen there should be a radiator that removes heat from the screen (and at the same time serves as a secondary screen), attached to the main body of the starship with thermal insulating beams. The need for such a design is explained by the fact that the incident atoms have a large kinetic energy, they will penetrate deeply into the screen and, slowing down in it, dissipate this energy in the form of heat. For example, at flight speed 0,75 with the energy of a hydrogen proton will be approximately 500 MeV - in units nuclear physics, which corresponds 8 10 -11 J. It will penetrate the screen to a depth of several millimeters and transfer this energy to vibrations of the screen atoms. And such particles will fly about 2 10 10 atoms and the same number of hydrogen molecules per second per 1 cm 2, that is, every second for 1 cm 2 screen surface will arrive 4.8 J of energy converted into heat. And the problem is that in space this heat can be removed only by emitting electromagnetic waves into the surrounding space (there is no air and water there). This means that the screen will heat up until its thermal electromagnetic radiation is equal to the power coming from the incoming particles. Thermal radiation by a body of electromagnetic energy is determined by the Stefan-Boltzmann law, according to which the energy radiated per second with 1 cm 2 of the surface is q=sТ 4 where s\u003d 5.67 10 -12 J / cm 2 K 4 is Stefan's constant, and T - body surface temperature. The equilibrium condition will be sT 4 \u003d Q where Q - incoming power, that is, the temperature of the screen will be T=(Q/s) 1/4 . Substituting the appropriate values into this formula, we find that the screen will heat up to a temperature 959 o K = 686 about C. It is clear that at high speeds this temperature will be even higher. This means, for example, that the screen cannot be made of aluminum (its melting point is only 660 o C), and it must be thermally insulated from the main body of the starship - otherwise the living compartments will be unacceptably heated. And to facilitate the thermal regime of the screen, it is necessary to attach a radiator with a large radiation surface (it can be made of aluminum), for example, in the form of a cellular system of longitudinal and transverse ribs, while the transverse ribs will simultaneously act as secondary screens, protecting the living compartments from fragments and braking radiation particles entering the screen, etc.

But protection from atoms and molecules is not the main problem of interstellar flight. Astronomers, observing the absorption of light from stars, have found that there is a significant amount of dust in interstellar space. Such particles, which strongly scatter and absorb light, have dimensions 0.1-1 micron and mass order 10 -13 g, and their concentration is much less than the concentration of atoms and is approximately equal to r=10 -12 1/cm 3 Judging by their density ( 1 g / cm 3) and refractive index ( n=1.3 ) they are mainly snowballs, consisting of frozen cosmic gases (hydrogen, water, methane, ammonia) with an admixture of solid carbon and metal particles. Apparently, it is from them that comet nuclei are formed, which have the same composition. And although they should be rather loose formations, at near-light speeds they can cause great harm.
At such velocities, relativistic effects begin to manifest themselves strongly, and the kinetic energy of the body in the relativistic region is given by

As you can see, the energy of the body increases sharply as v approaches the speed of light c: So, at a speed 0.7 with a speck of dust m=10 -13 g has kinetic energy 3.59 J (see Table 1) and getting it into the screen is equivalent to an explosion in it for about 1 mg of TNT. At speed 0.99 with this speck of dust will have energy 54.7 J, which is comparable to the energy of a bullet fired from a Makarov pistol ( 80 J). At such speeds, it turns out that each square centimeter of the screen surface is continuously fired with bullets (and explosive ones) with a frequency 12 shots per minute. It is clear that no screen can withstand such exposure for several years of flight.

Table 1 Energy ratios

0.1 4.73 4.53 10 14 1.09 10 5 0.2 19.35 1.85 10 15 4.45 10 5 0.3 45.31 4.34 10 15 1.04 10 6 0.4 85.47 8.19 10 15 1.97 10 6 0.5 145.2 1.39 10 16 3.34 10 6 0.6 234.6 2.25 10 16 5.40 10 6 0.7 375.6 3.59 10 16 8.65 10 6 0.8 625.6 5.99 10 16 1.44 10 7 0.9 1214 1.16 10 17 2.79 10 7 0.99 5713 5.47 10 17 1.31 10 8 0.999 20049 1.92 10 18 4.62 10 8

v/c	1/(1-v 2 / c 2) 1/2	Ep	K	T
1.005
1.020
1.048
1.091
1.155
1.25
1.40
1.667
2.294
7.089
22.37

Designations: E r is the kinetic energy of the proton in MeV TO - kinetic energy of 1 kg of substance in J T - TNT equivalent of a kilogram in tons of TNT.

To assess the consequences of particle impact on the surface, you can use the formula proposed by F. Whipple, an expert on these issues (, p. 134), according to which the dimensions of the resulting crater are equal to

where d is the density of the screen material, Q is its specific heat of fusion.

But here it must be borne in mind that in fact we do not know how the dust particles will affect the screen material at such speeds. This formula is valid for small impact velocities (on the order of 50 km / s or less), and at near-light speeds of impact, the physical processes of impact and explosion should proceed quite differently and much more intensively. One can only assume that, due to relativistic effects and the large inertia of the material of the dust grain, the explosion will be directed deep into the screen, like a cumulative explosion, and will lead to the formation of a much deeper crater. The above formula reflects the general energy relationships, and we will assume that it is suitable for assessing the results of an impact and for near-light speeds.
Apparently, the best material for the screen is titanium (due to its low density and physical characteristics), for it d=4.5 g / cm 3, and Q=315 KJ / Kg, which gives

d=0.00126 E 1/3 meters

At v=0.1 c we get E=0.045 J and d=0.00126 0.356=0.000448 m= 0.45 mm. It's easy to find that going the way in 1 light year, starship screen will meet n=rs\u003d 10 -12 9.46 10 17 \u003d 10 6 dust particles for every cm 2, and every 500 dust particles will tear off a layer 0.448 mm screen. So after 1 light-year path the screen will be erased by the thickness 90 see It follows that for a flight at such speeds, say, to Proxima Centauri (only there), the screen should have a thickness of approximately 5 meters and a mass of about 2.25 thousand tons. At high speeds, the situation will be even worse:

Table 2 Thickness X titanium erased for 1 light year travel

0.1 0.448 0.9 0.2 0.718 3.66 0.3 0.955 9.01 0.4 1.178 16.4 0.5 1.41 27.6

v/c	E	d mm	X m
0.045
0.185
0.434
0.818
1.39

. . .

As can be seen, at v/c >0.1 the screen will have to have an unacceptable thickness (tens and hundreds of meters) and weight (hundreds of thousands of tons). Actually, then the starship will consist mainly of this screen and fuel, which will require several million tons. Due to these circumstances, flights at such speeds are impossible.

The considered abrasive action of cosmic dust does not actually exhaust the entire spectrum of influences to which a spacecraft will be subjected during an interstellar flight. Obviously, in interstellar space there are not only dust particles, but also bodies of other sizes and masses, however, astronomers cannot directly observe them due to the fact that although their sizes are larger, they themselves are smaller, so that they do not make a tangible contribution to absorption of stellar light (the dust grains considered earlier have a size of the order of the wavelength of visible light and therefore absorb and scatter it strongly, and there are quite a lot of them, so astronomers mainly observe them).
But one can get an idea of the bodies in deep space by the bodies that we observe in the solar system, including those near the Earth. After all, as measurements show, the solar system is moving relative to neighboring stars approximately in the direction of Vega with a speed 15.5 km / s, which means that every second it sweeps up more and more volumes of outer space along with its contents. Of course, not everything near the Sun came from outside, many bodies were originally elements of the solar system (planets, asteroids, many meteor showers). But astronomers have repeatedly observed, for example, the flight of some comets that flew in from interstellar space and flew there. This means that there are also very large bodies (weighing millions and billions of tons), but they are very rare. It is clear that bodies of almost any mass can meet there, but with different probabilities. And in order to estimate the probability of meeting various bodies in interstellar space, we need to find the mass distribution of such bodies.
First of all, you need to know what happens to bodies when they are in the solar system. This issue has been well studied by astrophysicists, and they have found that the lifetime of not too large bodies in the solar system is very limited. So, small particles and dust particles with masses less than 10 -12 g are simply pushed out of the solar system by streams of light and protons from the Sun (as can be seen from the tails of comets). For larger particles, the result is the opposite: as a result of the so-called Poynting-Robertson effect, they fall on the Sun, gradually descending towards it in a spiral over a time of the order of several tens of thousands of years.
This means that the sporadic particles and micrometeorites observed in the solar system (not related to its own meteor showers) fell into it from the surrounding space, since its own particles of this type have long disappeared. Therefore, the desired dependence can be found from observations of sporadic particles in the solar system itself. Such observations have been conducted for a long time, and the researchers came to the conclusion (,) that the law of distribution of cosmic bodies by mass has the form N(M)=N 0 /M i Direct measurements for sporadic meteors in the mass range from 10 -3 before 10 2 g (, p. 127) give for the flux density of meteors with a mass of more than M gram addiction

F( M)=Ф(1)/ M 1.1

The most reliable results on this issue were obtained from measurements of microcraters formed on the surfaces of spacecraft (, p. 195), they also give k=1.1 in the range of masses from 10 -6 before 10 5 d. For smaller masses, it remains to be assumed that this distribution holds for them as well. For the magnitude of the particle flux is more massive 1 g different measurements give values 10 -15 1) 2 10 -14 1 / m 2 s, and since the magnitude of the flow is related to the spatial density of bodies by the ratio F=rv , then from here it can be found that the concentration in space of bodies with a mass of more than M is given by the formula

r( M)=r 1 /M 1.1

where parameter r1 can be found by taking the average speed of sporadic meteor particles equal to v=15 km / s (as can be seen from the measurements of P. Millman), then r 1 \u003d F (1) / v turns out to be equal on average 5 10 -25 1/cm3.
From the distribution obtained, it can be found that the concentration of particles whose masses are greater than 0.1 g is on average equal to r(0.1)=r1(10) 1.1=6.29 10 -24 1 / cm 3, which means that on the way to 1 light year starship will meet on 1 cm 2 surfaces n=rs\u003d 5.9 10 -6 such particles that with a total area S=100 m 2 = 10 6 cm 2 will be at least 5 particles are more massive 0.1 g for the entire cross section of the starship. And each such particle v=0.1 c has more energy 4.53 10 10 J, which is equivalent to a cumulative explosion 11 tons of TNT. Even if the screen withstands this, then the following will happen: since the particle is unlikely to hit exactly at the center of the screen, then at the moment of the explosion, a force will appear that turns the starship around its center of mass. Firstly, it will slightly change the direction of flight, and, secondly, it will turn the spaceship, substituting its side for the oncoming flow of particles. And the starship will be quickly shredded by them, and if there are reserves of antimatter on board, then everything will end in a series of annihilation explosions (or one big explosion).
Some authors express the hope that the dangerous meteorite can be evaded. Let's see how it will look at sublight speed v=0.1 c. meteorite weighing 0.1 g has a size of about 2 mm and energy equivalent 10.9 tons of TNT. Getting it into the starship will result in a fatal explosion, and you will have to dodge it. Let us assume that a starship radar is capable of detecting such a meteorite at a distance X=1000 km - although it is not clear how this will be done, since on the one hand, the radar must be in front of the screen in order to perform its function, and on the other hand, behind the screen so as not to be destroyed by the flow of incoming particles.
But suppose, then in time t = x/v = 0.03 seconds, the starship must react and deviate to a distance at= 5 m (including the diameter of the starship 10 meters). This means that it must acquire transverse speed u=y/t - again for the time t , that is, its acceleration must be at least a=y/t2 = 150 m/s 2 . This is the acceleration in 15 times greater than normal, and none of the crew, and even many instruments of the starship, can withstand it. And if the mass of the starship is about 50 000 tons, then this will require force F=am= 7.5 10 9 newton. Such a force for a time in thousandths of a second can only be obtained by producing a powerful explosion on a starship: a chemical explosion produces a pressure of the order 10 5 atmospheres= 10 10 Newton/m 2 and it will be able to roll the starship to the side. That is, in order to evade the explosion, you need to blow up the starship ...
Thus, even if it is possible to accelerate the spacecraft to subluminal speed, then it will not reach the final goal - there will be too many obstacles on its way. Therefore, interstellar flights can be carried out only at significantly lower speeds, on the order of 0.01 with or less. This means that the colonization of other worlds can take place at a slow pace, since each flight will take hundreds and thousands of years, and for this it will be necessary to send large colonies of people to other stars capable of existing and developing independently. For such a purpose, a small asteroid made of frozen hydrogen can be suitable: inside it, you can arrange a city of suitable sizes, where astronauts will live, and the material of the asteroid itself will be used as fuel for thermonuclear power plant and engine. Modern science cannot offer other ways of deep space exploration.
In all this there is only one positive aspect: the invasion of hordes of aggressive aliens does not threaten the Earth - this is too complicated a matter. But the reverse side of the medal is that it will not be possible to reach worlds where there are "brothers in mind" over the next several tens of thousands of years. Therefore, the fastest way to detect aliens is to establish communications using radio signals or some other signals.

Bibliography

1. Novikov I.D. Theory of relativity and interstellar flights - M.: Knowledge, 1960
2. Perelman R.G. Goals and ways of space exploration - M.: Nauka, 1967
3. Perelman R.G. Engines of galactic ships - M.: ed. USSR Academy of Sciences, 1962
4. Burdakov V.P., Danilov Yu.I. External resources and astronautics - M.: Atomizdat, 1976
5. Zenger E., On the mechanics of photon rockets - M.: ed. Foreign Literature, 1958
6. Zakirov U.N. Mechanics of relativistic space flights - M.: Nauka, 1984
7. Allen K.W. Astrophysical quantities - M.: Mir, 1977
8. Martynov D.Ya. Course of General Astrophysics - M.: Nauka, 1971
9. Physical quantities (Handbook) - M.: Energoatomizdat, 1991
10. V. P. Burdakov and F. Yu. Physical foundations of astronautics (cosmic physics) - M.: Atomizdat, 1974
11. Spitzer L. The space between the stars - M.: Mir, 1986.
12. Lebedinets V.M. Aerosol in the upper atmosphere and cosmic dust - L .: Gidrometeoizdat, 1981
13. Babadzhanov P.B. Meteors and their observation - M.: Nauka, 1987
14. Akishin A.I., Novikov L.S. Impact environment on spacecraft materials - M.: Knowledge, 1983

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Interstellar flight is a journey between the stars of manned vehicles or automatic stations. Most often, interstellar flight is understood as a manned journey, sometimes with the possible colonization of extrasolar planets.

The construction of a squadron of interstellar ships will begin at the Lagrange points of the Earth-Moon system (points of gravitational equilibrium). For the most part, materials can be delivered from lunar bases - for example, containers with them are fired by electromagnetic guns and captured by special trap stations in the construction area. An engine for an interstellar spacecraft should be of the same order of magnitude as all the power consumed by humanity today. Based on foreseeable technologies and resource capabilities, it is possible to give an outline of future interstellar flights.

When considering a spacecraft of any purpose, it is convenient to divide it into two parts - the propulsion system and the payload. Under the propulsion system, it is customary to understand not only the engines themselves, but also fuel tanks, the necessary power structures. For the problem of interstellar flights, it is the propulsion system that is the key factor determining the feasibility of the project. However, the problems of creating a propulsion system are beyond the scope of this consideration. Now what is important for us is that there are technologies that, in the course of their development, may become acceptable for interstellar flights. Here in the first place is the technology of using inertial thermonuclear fusion for rocket propulsion. At the $3.5 billion American facility NIF (National Ignition Facility) for laser fusion research, results have already been obtained indicating that a rocket engine based on this principle can be created. An even more powerful installation of this type is being built near Sarov. These installations bear little resemblance to rocket engines, but if they are conditionally "cut" in half, get rid of foundations, walls and much equipment that is unnecessary in space, we will get a rocket engine that can be brought to the interstellar version. Without going into details, we note that such engines will necessarily be large, heavy and very powerful. An engine for an interstellar spacecraft should be of the same order of magnitude as all the power consumed by humanity today. Having such an engine (and if there is no such engine, then there is nothing to talk about), you can feel more free when considering the parameters of the payload. By analogy, if an extra 50 kg is already noticeable for a cyclist, then a diesel locomotive will not even notice the extra 50 tons.

Armed with this understanding, we can try to imagine the first interstellar expedition. In this case, it will be necessary to use the results of calculations and estimates that have been made, but here, for obvious reasons, cannot be reproduced.

One ship means hundreds of thousands of tons of payload, millions of tons of engines, tens of millions of tons of fuel. The numbers can be intimidating, but not to be too intimidating, they can be compared with other large construction projects. A long time ago, in 20 years, the Cheops pyramid weighing more than 6 million tons was built. Or already in our times - in Canada in 1965 the island "North Dame" was built. It took 15 million tons of soil alone, and the construction took only 10 months. Biggest sea ship-- Knock Nevis -- had a displacement of 825,614 tons. Construction in space has its own specific difficulties, but it also has some advantages, for example, lightening of the power elements due to weightlessness, the practical absence of restrictions on mass and size (on Earth, a sufficiently large structure will simply crush itself).

Approximately 95% of the mass of the interstellar spacecraft will be thermonuclear fuel. Probably, boron hydrogens will be used as its fuel, solid fuel, tanks are not needed, which greatly improves the characteristics of the ship and facilitates its construction. It is better to collect borohydrides not in the Earth-Moon system, but somewhere far away from the Sun, in the Saturn system, for example, in order to avoid sublimation losses. Construction time can be estimated at several decades. The term is not so great, and besides, the same builders will simultaneously carry out other works within the framework of the development of the solar system. Construction is better to start with the construction of residential blocks of the ship, in which builders and other specialists will settle. At the same time, during the construction and accumulation of fuel, the stability of the closed life support system will be tested for decades.

The closed life support system is probably the second most difficult issue after the engine problem. One person consumes about 5 kg of water, food and air per day, if you take everything with you, you will need more than 200 thousand tons of supplies. The solution is the reuse of resources, as it happens on planet Earth.

The full extent of the interstellar distances of flights can be felt only if we look at the means of carrying out such flights. Of course, such consideration is not intended to "feel the distance." Nor can it be considered as the design of a specific design of interstellar ships. The study of the issues of interstellar flights today is of an engineering-theoretical nature. It is impossible to prove the impossibility of interstellar flights, but no one has been able to prove their feasibility either. The way out of the situation is not simple - it is necessary to propose such a design of interstellar ships that would be perceived by the engineering and scientific community as feasible.

Flights of single interstellar ships, which are the rule in science fiction literature, are excluded; only a squadron of ships, about a dozen vehicles, can fly. This is a requirement for safety, and in addition - and ensuring the diversity of life through communication between the crews of different ships.

When the squadron is completed, it moves to the stored fuel reserves, docks with them and goes into flight. Apparently, acceleration will be very slow, and within a year or two, more mobile devices will be able to throw on ships what they forgot and take off board those who have changed their minds.

The flight will last 100-150 years. Slow acceleration with an acceleration of about a hundredth of the earth's for a decade, decades of inertia flight, and somewhat faster than acceleration, deceleration. Fast acceleration would significantly reduce the flight time, but it is not possible due to the inevitably large mass of the propulsion system.

The flight will not be as full of space adventures as described in science fiction literature. There are practically no external threats. Clouds of cosmic dust, swirls of space, gaps in time - all these paraphernalia of a threat do not pose a threat due to its absence. Even trivial meteorites are extremely rare in interstellar space. The main external problem is galactic cosmic radiation, cosmic rays. This is an isotropic flow of nuclei of elements that have high energy and, consequently, high penetrating power. On Earth, the atmosphere and the magnetic field protect us from them; in space, if the flight is long, special measures must be taken, shielding the living area of the ship so that the dose of cosmic radiation does not greatly exceed the earth's level. A simple constructive technique will help here - fuel reserves (and they are very large) are located around the living compartments and shield them from radiation for most of the flight time.