Kinematics of interstellar flights

Let the flight there and the flight back consist of three phases: uniformly accelerated acceleration, flight at a constant speed and uniformly accelerated deceleration.

The proper time of any clock has the form:

where is the speed of this clock. The earth's clocks are motionless (), and their proper time is equal to the coordinate time. The astronauts' watches have variable speed. Since the root of the integral remains less than unity all the time, the time of these clocks, regardless of the explicit form of the function, always turns out to be less. As a result.

If acceleration and deceleration are relativistically uniformly accelerated (with the self-acceleration parameter) during , and uniform motion is , then according to the ship's clock time will pass:

, where is the hyperbolic arcsine

Consider a hypothetical flight to the Alpha Centauri star system, distant from Earth at a distance of 4.3 light years. If time is measured in years and distances in light years, then the speed of light is equal to unity, and the unit acceleration per year/year² is close to the acceleration of gravity and is approximately equal to 9.5 m/s².

Let the spacecraft move half the way with unit acceleration, and let it slow down the second half with the same acceleration (). The ship then turns around and repeats the acceleration and deceleration stages. In this situation, the flight time in the earth's reference frame will be approximately 12 years, while according to the clock on the ship, 7.3 years will pass. The maximum speed of the ship will reach 0.95 of the speed of light.

In 64 years of its own time, a spacecraft with unit acceleration could potentially travel (returning to Earth) to the Andromeda Galaxy, 2.5 million light years away. years . About 5 million years will pass on Earth during such a flight. Developing twice the acceleration (which a trained person can easily get used to if a number of conditions are met and a number of devices are used, for example, suspended animation), one can even think about an expedition to the visible edge of the Universe (about 14 billion light years), which will take the cosmonauts about 50 years; However, having returned from such an expedition (after 28 billion years according to Earth's clock), its participants risk not finding alive not only the Earth and the Sun, but even our Galaxy. Based on these calculations, in order for astronauts to avoid future shock upon returning to Earth, the reasonable radius of accessibility for interstellar return expeditions should not exceed several tens of light years, unless, of course, any fundamentally new physical principles of movement in space-time are discovered. However, the discovery of numerous exoplanets gives reason to believe that planetary systems are found near a sufficiently large proportion of stars, so astronauts will have something to explore in this radius (for example, the planetary systems ε Eridani and Gliese 581).

Suitability of various types of engines for interstellar flights

The suitability of various types of engines for interstellar flight was considered at a meeting of the British Interplanetary Society in 1973 by Tony Martin. The nuclear-powered electric rocket engine has little acceleration, so it will take centuries to reach the desired speed, allowing it to be used only in generation ships. Thermal nuclear engines of the NERVA type have a sufficient amount of thrust, but a low speed of exhaust of the working mass, about 5-10 km/sec, so a huge amount of fuel is required to accelerate to the required speed. Thus, a ship with such an engine will be several orders of magnitude slower than a ship with an electric propulsion engine. A flight to a neighboring star on such a ship will take tens and hundreds of thousands of thousands of years (a flight to Alpha Centauri at a speed of 30 km/sec will take 40 thousand years). A ramjet engine would require a huge diameter funnel to collect rarefied interstellar hydrogen, which has a density of 1 atom per cubic centimeter. If a super-powerful electromagnetic field is used to collect interstellar hydrogen, the force loads on the generating coil will be so great that overcoming them seems unlikely even for future technology.

Interstellar expedition projects

Starship-rocket projects

Project "Orion"

The rocket ship of the Daedalus project turned out to be so huge that it would have to be built in outer space. It was supposed to weigh 54,000 tons (almost all the weight is rocket fuel) and could accelerate to 7.1% of the speed of light, carrying a payload weighing 450 tons. Unlike the Orion project, designed to use tiny atomic bombs , the Daedalus project involved the use of miniature hydrogen bombs with a mixture of deuterium and helium-3 and an ignition system using electron beams. But huge technical problems and concerns about nuclear propulsion meant that the Daedalus project was also shelved indefinitely.

The technological ideas of Daedalus were used in the project of the thermonuclear starship Icarus.

Projects of starships, the propulsion of which is the pressure of electromagnetic waves.

In 1971, in a report by G. Marx at a symposium in Byurakan, it was proposed to use X-ray lasers for interstellar travel. The possibility of using this type of propulsion was later investigated by NASA. As a result, the following conclusion was made: “If the possibility of creating a laser operating in the X-ray wavelength range is found, then we can talk about the real development of an aircraft (accelerated by the beam of such a laser) that will be able to cover distances to the nearest stars much faster than all known currently rocket-powered systems. Calculations show that using the space system considered in this work, it is possible to reach the star Alpha Centauri... in about 10 years."

In 1985, R. 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 36th International Astronomical Congress, a project for a laser starship was proposed, 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.

The advantage of a solar sailboat is that there is no fuel on board. Its disadvantage is the inability to use a sail to travel back to Earth, so it is good for launching automatic probes, stations and cargo ships, but is of little use for manned return flights (or astronauts will need to take a second laser with a reserve of fuel for installation at the destination , which actually negates all the advantages of a sailboat).

Annihilation engines

Theoretical 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. The engine they proposed is faster than other theoretical developments due to a special nozzle design. However, the main problems in creating annihilation rockets ( English) with such engines are the production of the required amount of antimatter, as well as its storage. As of May 2011, the record storage time for antihydrogen atoms was 1000 seconds (~16.5 minutes). A 2006 NASA estimate estimated that it cost approximately US$25 million to produce a milligram of positrons. One gram of antihydrogen would cost $62.5 trillion, according to a 1999 estimate.

Ramjet engines powered by interstellar hydrogen

The main component of the mass of modern rockets is the mass of fuel required by the rocket for acceleration. If we can somehow use the environment surrounding the rocket as a working fluid and fuel, we can significantly reduce the mass of the rocket and thereby achieve high speeds.

Another disadvantage of a thermonuclear ramjet engine is the limited speed that a ship equipped with it can reach (no more than 0.119 c= 35.7 thousand km/s). This is due to the fact that when capturing each hydrogen atom (which can, to a first approximation, be considered motionless relative to the stars), the ship loses a certain momentum, which can be compensated by engine thrust only if the speed does not exceed a certain limit. To overcome this limitation, it is necessary to utilize the kinetic energy of captured atoms as completely as possible, which seems to be a rather difficult task.

Let's say the screen caught 4 hydrogen atoms. When a fusion reactor operates, four protons are converted into one alpha particle, two positrons and two neutrinos. For simplicity, we will neglect neutrinos (taking into account neutrinos will require an accurate calculation of all stages of the reaction, and losses due to neutrinos are about a percent), and annihilate positrons with 2 electrons remaining from hydrogen atoms after removing protons from them. Another 2 electrons will be used to turn the alpha particle into a neutral helium atom, which, thanks to the energy received from the reaction, will be accelerated in the engine nozzle.

The final reaction equation without taking into account neutrinos:

4edit] Photon engine on magnetic monopoles

If some variants of Grand Unified theories are valid, such as the Hooft-Polyakov model, then it is possible to build a photon engine that does not use antimatter, since a magnetic monopole can hypothetically catalyze the decay of a proton into a positron and a π 0 meson:

π 0 quickly decays into 2 photons, and the positron annihilates with the electron, as a result the hydrogen atom turns into 4 photons, and only the mirror problem remains unsolved.

A photon engine based on magnetic monopoles could also operate in a direct-flow scheme.

At the same time, most modern Grand Unified theories do not include magnetic monopoles, which casts doubt on this attractive idea.

Interstellar Ship Braking Systems

Several methods have been proposed:

1. Braking on internal sources - rocket

2. Braking due to a laser beam sent from the Solar System.

3. Magnetic field braking using Zubrin’s Magnetic Sail on superconductors.

Generation ships

Interstellar travel is also possible using starships that implement the concept of “generation ships” (for example, like O’Neill’s colonies). In such spaceships, a closed biosphere is created and maintained, capable of maintaining and reproducing itself for several thousand years. The flight occurs at low speed and takes a very long time, during which many generations of astronauts manage to change.

Environmental hazards

This problem was examined in detail by Ivan Korznikov in the article “The Realities of Interstellar Flights”. The collision with interstellar dust will occur at near-light speeds and the physical impact will resemble micro-explosions. At speeds greater than 0.1 C, the protective screen must have a thickness of tens of meters and a mass of hundreds of thousands of tons. But this screen will only reliably protect from interstellar dust. A collision with a meteorite will have fatal consequences. Ivan Korznikov gives calculations that at a speed of more than 0.1 C, the spacecraft will not have time to change the flight path and avoid a collision. Ivan Korznikov believes that at sublight speed the spacecraft will collapse before reaching its target. In his opinion, interstellar travel is possible only at significantly lower speeds (up to 0.01 C).

Energy and resources

Interstellar flight will require large reserves of energy and resources that will have to be carried with you. This is one of the little-studied problems in interstellar astronautics.

For example, the most developed project to date, “Daedalus” with a pulsed thermonuclear engine, would reach Barnard’s star (six light years) in half a century, spending 50 thousand tons of thermonuclear fuel (a mixture of deuterium and helium-3) and delivering a useful mass of 4 thousand to the target tons

“Technology for Youth” 1991 No. 10, pp. 18-19

Tribune of bold hypotheses

Vladimir ATSYUKOVSKY,
Candidate of Technical Sciences,
Zhukovsky, Moscow region.

Is interstellar travel possible?

The press was overwhelmed by a wave of reports about UFOs. Eyewitnesses claim to have seen a UFO that was clearly man-made. They have no doubt that they observed spaceships of alien civilizations. However, our consciousness refuses to accept this: for the planets of the solar system, the presence of civilizations other than Earth is almost impossible, because there are no conditions for life on them, at least on their surface. Maybe below the surface? Unlikely, although...

And on the planets of other systems, there may be life, but it is very far from them: the nearest 28 stars are located within the range from 4 (Nearest Centauri) to 13 light years (Kapteyn’s star). Stars such as Sirius A and B, Procyon A and B, Tau Ceti are located within this interval. Not close! If ships fly back and forth at the speed of light, then it will take them from 8 to 26 years in both directions, and this is only for the nearest stars. Not counting the time for acceleration and deceleration. This is hardly advisable, which means you need to fly faster than light.

Well, let's estimate how long it will take to accelerate to such speeds (and braking). For the sake of clarity, the results are summarized in a table, from which you can immediately find out the time required to achieve a particular speed at a particular acceleration. It turns out: if we assume the permissible duration of a one-way trip to be equal to one month, then you need to fly at a speed of the order of many tens of the speeds of light, and accelerate (and decelerate) with the acceleration of many hundreds of earthly accelerations. Hmmm!.. And for all this we still need to get energy somewhere! One inevitably wonders: are interstellar flights even feasible? But where do UFOs come from then? Moreover, they behave defiantly: they suddenly disappear, maneuver at right angles, emit something... What if...

After all, what do we need, after all? Just answer three questions:

1. Is it in principle possible to fly at speeds exceeding the speed of light? (At school they taught me not to.)

2. Is it possible to accelerate strongly without destroying the body? (According to modern concepts, already 10-fold overload is the maximum permissible.)

3. Is it possible to obtain energy for acceleration and braking? (Calculations show that no thermonuclear energy is enough for this.)

Oddly enough, all questions, despite the skeptical notes in brackets, already have positive answers today. It is impossible to fly at speeds exceeding the speed of light only because of the ban imposed by A. Einstein. But why on earth is his theory of relativity elevated to the rank of absolute truth? After all, it comes from postulates, that is, the author’s inventions, which themselves are based on false premises. For example, in 1887, in the famous Michelson experiment, the ethereal wind was discovered, although its magnitude turned out to be less than expected (then the concept of a boundary layer was not known). What happens? On the one hand, SRT - the special theory of relativity - cannot exist if there is an ether. On the other hand, GTR - the general theory of relativity - as Einstein himself wrote in the articles “On the Ether” and “Ether and the Theory of Relativity”, always presupposes the presence of ether. How to understand this contradiction?

My critical review of all the main experiments on SRT and GTR (see “Logical and experimental foundations of the theory of relativity. Analytical review.” M., MPI, 1990, 56 pp.) showed that among them there are no unambiguously confirming this theory! That is why it can be discounted and not taken into account here. Moreover, P. Laplace also established that the speed of propagation of gravitational disturbances is no less than 50 million times higher than the speed of light, and the entire experience of celestial mechanics, which operates exclusively with static formulas that assume an infinitely large speed of propagation of gravity, confirms this. In short, there is no ban on sub-light speeds, it was a false alarm.

Let's move on to the second question. Let's consider how an astronaut accelerates? The rocket gases press on the wall of the combustion chamber, which presses on the rocket, the rocket presses on the back of the chair, and the back of the chair presses on it. And the body, the entire mass of the astronaut, trying to remain at rest, is deformed and under strong influences can collapse. But if the same astronaut fell in the gravitational field of some star, then, although he would accelerate much faster, he would not experience any deformation at all, because all the elements of his body are accelerated simultaneously and equally. The same thing will happen if you blow ether onto an astronaut. In this case, the flow of ether - a real viscous gas - will accelerate each proton and the astronaut as a whole, without deforming the body (remember the science fiction novel by A. Belyaev “Ariel”). Moreover, the acceleration can have any value, as long as the flow is uniform. So there are opportunities here too.

And finally, where do you get the energy? According to my data (see “General ether dynamics. Modeling the structures of matter and fields based on ideas about gas-like ether.” M., Energoatomizdat, 1990, 280 pp), ether is a real gas of a fine structure, compressible and viscous. True, its viscosity is quite small, and this has practically no effect on the deceleration of planets, but at high speeds it plays a very noticeable role. The ether pressure is enormous, more than 2 x 10 in 29 atm (2 x 10 in 32 N/sq. m), density - 8.85 x 10 in - 12 kg/cubic. m (in near-Earth space). And as it turned out, there is a natural process in it that can supply us with an unlimited amount of energy at any point in space in portions of any size... We are talking about vortices.

Where do ordinary tornadoes get their kinetic energy? It is formed spontaneously from the potential energy of the atmosphere. And note: if the latter is practically impossible to use, then the first can be used, for example, by forcing a tornado to rotate a turbine. Everyone knows that a tornado resembles a trunk - thicker at the base. Analysis of this circumstance showed that it is compressed by atmospheric pressure. Pressure external to it causes gas particles in the body of a tornado to move in a spiral during the compression process. The difference in pressure forces - external and internal (plus centrifugal force) gives a projection of the resulting force onto the trajectory of gas particles (Fig. 1) and causes them to accelerate in the body of the tornado. It becomes thinner, and the speed of movement of its wall increases. In this case, the law of conservation of angular momentum mrv = const applies, and the more compressed the tornado is, the greater the speed of movement. Thus, the entire atmosphere of the planet works on each tornado; Its energy is based on air density equal to 1 kg / cubic meter. m, and a pressure equal to 1 atm (10 in 5 N/sq. m). And in the ether, the density is 11 orders of magnitude less, but the pressure is 29 (!) orders of magnitude higher. And the ether also has its own mechanism capable of supplying energy. This is BL, ball lightning.

The ether-dynamic model of BL is the only one (!) capable of explaining all its features in totality. And what is missing today to obtain environmentally friendly energy from the ether is to learn how to create artificial CMM. Of course, after we learn how to create conditions for vortex formation in the ether. But we not only don’t know how to do this, but we don’t even know which way to approach it. An extremely tough nut to crack! One thing is encouraging: after all, nature somehow manages to create them, these CMMs! And if so, then perhaps someday we too will be able to manage. And then there will be no need for all kinds of nuclear power plants, hydroelectric power plants, thermal power plants, thermal power plants, wind power plants, solar power plants and other power plants. Having any desired amount of energy in any place, humanity will approach solving environmental problems in a completely different way. Of course, provided that he will have to live peacefully on his planet, and what the hell, not only his native Earth will be destroyed, but also the entire solar system! You see, with energy the issue can be resolved. At the same time, pay attention to an important detail - with this method there will be no need to accelerate and slow down the mass of fuel, which now largely determines the mass of the ship.

Well, what about the interstellar ship itself, how should it be designed? Yes, at least in the form of the already familiar “flying saucer”. (Fig. 2.) In its front part there are two “ether intakes” that absorb ether from the surrounding space. Behind them are vortex formation chambers, in which the ether flows swirl and self-compact. Further along the vortex ducts, the ethereal tornadoes are conveyed to the annihilation chamber, where they (with identical screw movements, but directed in the opposite direction; annihilate each other with the plow. The densified ether is no longer restrained by the boundary layer and explodes, scattering in all directions. The jet stream is thrown back, and forward - a flow that captures the entire ship and the astronaut’s body, which accelerates without deformation. And the ship flies ahead of light, in ordinary Euclidean space and in ordinary time...

But what about the paradoxes of twins, the increase in mass and the reduction in length? But no way. Postulates - they are postulates - free inventions, the fruits of free imagination. And they must be swept aside along with the “theory” that gave birth to them. For if the time has come for humanity to solve applied problems, then it should not be stopped by any inflated authorities with their speculative barriers that came from nowhere.

Note: The books mentioned can be ordered at the address: 140160, Zhukovsky, Moscow region, PO Box 285.

On April 12, 2016, the famous British physicist Stephen Hawking and Russian businessman and philanthropist Yuri Milner announced the allocation of $100 million to finance the project Breakthrough Starshot. The goal of the project was to develop technologies for creating spacecraft capable of making an interstellar flight to Alpha Centauri.

Thousands of science fiction novels describe giant photon starships the size of a small (or large) city, leaving for interstellar flight from the orbit of our planet (less often, from the surface of the Earth). But, according to the authors of the project, Breakthrough Starshot, everything will happen completely differently: on one significant day two thousand of some year, not one or two, but hundreds and thousands of small spaceships the size of a fingernail and weighing 1 g will launch to one of the nearest stars, Alpha Centauri. And each of them will have a thin solar sail with an area of ​​16 m 2, which will carry the spaceship with ever-increasing speed forward - to the stars.

"Shot to the Stars"

The basis of the project Breakthrough Starshot was an article by UC Santa Barbara physics professor Philip Lubin, “A Plan for Interstellar Flight” ( A Roadmap to Interstellar Flight). The main stated goal of the project is to make interstellar flights possible within the lifetime of the next generation of people, that is, not in centuries, but in decades.

Immediately after the official announcement of the program Starshot The authors of the project were hit by a wave of criticism from scientists and technical specialists in various fields. Critical experts noted numerous incorrect assessments and simply “blank spots” in the program plan. Some comments were taken into account and the flight plan was slightly adjusted in the first iteration.

So, the interstellar probe will be a space sailboat with an electronic module StarChip weighing 1 g, connected by heavy-duty straps to a solar sail with an area of ​​16 m 2, a thickness of 100 nm and a mass of 1 g. Of course, the light of our Sun is not enough to accelerate even such a light structure to speeds at which interstellar travel will not last for millennia. Therefore, the main highlight of the project StarShot- This is acceleration using powerful laser radiation that is focused on the sail. Lubin estimates that with a laser beam power of 50–100 GW, the acceleration will be about 30,000 g, and in a few minutes the probe will reach the speed of 20% of light. The flight to Alpha Centauri will last about 20 years.

Unanswered questions: a wave of criticism

Philip Lubin in his article provides numerical estimates of the points of the plan, but many scientists and specialists are very critical of these data.

Of course, to develop such an ambitious project as Breakthrough Starshot, it takes years of work, and $100 million is not such a large amount for work of this scale. This especially applies to ground infrastructure - a phased array of laser emitters. Installing such a capacity (50–100 GW) will require a gigantic amount of energy, that is, at least a dozen large power plants will need to be built nearby. In addition, it will be necessary to remove a huge amount of heat from the emitters over several minutes, and how to do this is still completely unclear. There are such unanswered questions in the project Breakthrough Starshot a huge amount, but so far the work has just begun.

“The scientific council of our project includes leading experts, scientists and engineers in various relevant fields, including two Nobel laureates,” says Yuri Milner. - And I have heard very balanced assessments of the feasibility of this project. In doing so, we certainly rely on the combined expertise of all members of our scientific council, but at the same time we are open to broader scientific discussion.”

Under the starry sails

One of the key details of the project is the solar sail. In the original version, the sail area was initially only 1 m 2, and because of this, it could not withstand heating during acceleration in the laser radiation field. The new version uses a sail with an area of ​​16 m2, so the thermal regime, although quite harsh, but, according to preliminary estimates, should not melt or destroy the sail. As Philip Lubin himself writes, it is planned to use not metallized coatings, but completely dielectric multilayer mirrors as the basis for the sail: “Such materials are characterized by a moderate reflection coefficient and extremely low absorption. Let’s say, optical glasses for fiber optics are designed for high light fluxes and have an absorption of about twenty trillionths per 1 micron of thickness.” It is not easy to achieve a good reflection coefficient from a dielectric with a sail thickness of 100 nm, which is much less than the wavelength. But the project's authors have some hope in using new approaches, such as monolayers of metamaterial with a negative refractive index.

Solar sail

One of the main elements of the project is a solar sail with an area of ​​16 m2 and a mass of only 1 g. The sail material is multilayer dielectric mirrors that reflect 99.999% of the incident light (according to preliminary calculations, this should be enough to prevent the sail from melting in a radiation field of 100- GW laser). A more promising approach, which makes it possible to make the thickness of the sail smaller than the wavelength of reflected light, is to use a monolayer of metamaterial with a negative refractive index as the basis of the sail (such a material also has nanoperforation, which further reduces its mass). The second option is to use a material not with a high reflection coefficient, but with a low absorption coefficient (10 −9), such as optical materials for light guides.

“You also have to consider that the reflection from dielectric mirrors is tuned to a narrow range of wavelengths, and as the probe accelerates, the Doppler effect shifts the wavelength by more than 20%,” says Lubin. - We took this into account, so the reflector will be adjusted to approximately twenty percent of the radiation bandwidth. We designed such reflectors. If required, reflectors with larger bandwidths are also available.”

Laser machine

The main power plant of the spaceship will not fly to the stars - it will be located on Earth. This is a ground-based phased array of laser emitters measuring 1×1 km. The total laser power should be from 50 to 100 GW (this is equivalent to the power of 10–20 Krasnoyarsk hydroelectric power stations). It is supposed to use phasing (that is, changing the phases on each individual emitter) to focus radiation with a wavelength of 1.06 μm from the entire grating into a spot with a diameter of several meters at distances up to many millions of kilometers (the maximum focusing accuracy is 10 −9 radians). But such focusing is greatly hampered by the turbulent atmosphere, which blurs the beam into a spot approximately the size of an arcsecond (10 −5 radians). Improvements of four orders of magnitude are expected to be achieved using adaptive optics (AO), which will compensate for atmospheric distortions. The best adaptive optics systems in modern telescopes reduce blur to 30 milliarcseconds, which means there are still about two and a half orders of magnitude left to the intended target. “To overcome small-scale atmospheric turbulence, the phased array must be broken down into very small elements, the size of the emitting element for our wavelength should be no more than 20–25 cm,” explains Philip Lubin. - This is at least 20 million emitters, but this number does not scare me. For feedback in the AO system, we plan to use many reference sources - beacons - both on the probe, on the mother ship, and in the atmosphere. In addition, we will track the probe on its way to the target. We also want to use the stars as a buoy to adjust the phasing of the array when receiving the signal from the probe upon arrival, but will track the probe to be sure.”

Arrival

But then the probe arrived in the Alpha Centauri system, photographed the surroundings of the system and the planet (if there are any). This information must be somehow transmitted to Earth, and the power of the probe's laser transmitter is limited to a few watts. And after five years, this weak signal must be received on Earth, isolating stars from the background radiation. According to the authors of the project, the probe maneuvers at the target in such a way that the sail turns into a Fresnel lens, focusing the probe signal in the direction of the Earth. It is estimated that an ideal lens with ideal focusing and ideal orientation amplifies a 1 W signal to 10 13 W isotropic equivalent. But how can we consider this signal against the background of much more powerful (by 13–14 orders of magnitude!) radiation from the star? “The light from the star is actually quite weak because the linewidth of our laser is very small. A narrow line is a key factor in reducing background, says Lubin. - The idea of ​​making a Fresnel lens out of a sail based on a thin-film diffractive element is quite complex and requires a lot of preliminary work to understand exactly how best to do this. This point is actually one of the main ones in our project plan.”

Interstellar flight is not a matter of centuries, but of decades

Yuri Milner ,
Russian businessman and philanthropist,
Founder of Breakthrough Initiatives:

Over the past 15 years, significant, one might say, revolutionary advances have taken place in three technological areas: miniaturization of electronic components, the creation of a new generation of materials, and also the reduction in cost and increase in laser power. The combination of these three trends leads to the theoretical possibility of accelerating a nanosatellite to almost relativistic speeds. At the first stage (5–10 years), we plan to conduct a more in-depth scientific and engineering study to understand how feasible this project is. On the project website there is a list of about 20 serious technical problems, without solving which we will not be able to move forward. This is not a definitive list, but based on the opinion of the scientific council, we believe that the first stage of the project has sufficient motivation. I know that the star sail project is subject to serious criticism from experts, but I think that the position of some critical experts is associated with a not entirely accurate understanding of what we are really proposing. We are not financing a flight to another star, but rather realistic multi-purpose developments related to the idea of ​​an interstellar probe only in a general direction. These technologies will be used both for flights in the solar system and for protection from dangerous asteroids. But setting such an ambitious strategic goal as interstellar flight seems justified in the sense that the development of technology over the past 10-20 years probably makes the implementation of such a project not a matter of centuries, as many assumed, but rather of decades.

On the other hand, a phased array of optical emitters/radiation receivers with a total aperture of a kilometer is an instrument capable of seeing exoplanets from distances of tens of parsecs. Using tunable wavelength receivers, the composition of the atmosphere of exoplanets can be determined. Are probes needed at all in this case? “Certainly, using a phased array as a very large telescope opens up new possibilities in astronomy. But, adds Lubin, we plan to add an infrared spectrometer to the probe as a longer-term program in addition to the camera and other sensors. We have a great photonics group at UC Santa Barbara that is part of the collaboration.”

But in any case, according to Lubin, the first flights will be made within the solar system: “Because we can send a huge number of probes, this gives us many different possibilities. We can also send similar small ( wafer-scale, that is, on a chip) probes on conventional rockets and use the same technologies to study the Earth or the planets and their satellites in the solar system."

The editors thank the newspaper “Troitsky Option - Science” and its editor-in-chief Boris Stern for their assistance in preparing the article.

Interstellar flight is travel between stars by manned vehicles or automatic stations. Most often, interstellar flight refers to manned travel, 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). Materials, for the most part, 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. The engine for an interstellar ship must have the same order of power as all the power consumed by humanity today. Based on foreseeable technologies and resource capabilities, it is possible to provide an outline of future interstellar travel.

When considering a spacecraft for any purpose, it is convenient to divide it into two parts - the propulsion system and the payload. The propulsion system usually means not only the engines themselves, but also fuel tanks and the necessary power structures. For the problems of interstellar travel, 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. What is important for us now is that there are technologies that, in the course of their development, can become acceptable for interstellar flights. Here the technology of using inertial thermonuclear fusion for rocket propulsion comes first. The American NIF (National Ignition Facility) installation for researching laser thermonuclear fusion worth 3.5 billion dollars has already obtained results indicating that a rocket engine can be created on this principle. An even more powerful installation of this type is being built near Sarov. These installations bear little resemblance to rocket engines, but if we roughly “cut” them in half, get rid of foundations, walls and a lot of equipment unnecessary in space, we will get a rocket engine that can be upgraded to an interstellar version. Without going into detail, we note that such engines will necessarily be large, heavy and very powerful. The engine for an interstellar ship must have the same order of power 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 won’t even notice the extra 50 tons.

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

The construction of a squadron of interstellar ships will begin at the Lagrange points of the Earth-Moon system (points of gravitational equilibrium). Materials, for the most part, 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.

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 to avoid being too intimidated, they can be compared to other major 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, North Dame Island was built. Only 15 million tons of soil was required, and construction took only 10 months. The largest 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 power elements due to weightlessness, the virtual absence of restrictions on mass and size (on Earth, a large enough structure will simply crush itself).

Approximately 95% of the mass of the interstellar ship will be thermonuclear fuel. It will probably use boron hydrogen, the fuel will be solid, tanks will not be needed, which greatly improves the characteristics of the ship and makes its construction easier. It is better to collect borohydrides not in the Earth-Moon system, but somewhere away from the Sun, in the Saturn system, for example, to avoid losses due to sublimation. Construction time can be estimated at several decades. The period is not so long, and in addition, the same builders will simultaneously carry out other work as part of the development of the Solar system. It is better to start construction with the construction of the ship’s residential blocks, in which builders and other specialists will live. At the same time, during construction and accumulation of fuel, the stability of the closed life support system will be tested for decades.

A closed life support system is probably the second most difficult issue after the engine problem. One person consumes approximately 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 to reuse resources as it happens on planet Earth.

The full scale of interstellar flight distances can only be experienced if we consider 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 interstellar travel today is of an engineering and theoretical nature. It is impossible to prove the impossibility of interstellar flights, but no one has been able to prove their feasibility. The way out of the situation is not easy - it is necessary to propose a design for interstellar ships that would be accepted by the engineering and scientific community as feasible.

Flights of single interstellar ships, which are the rule in science fiction literature, are excluded; flights of only a squadron of ships, about a dozen vehicles, are possible. This is a safety requirement, and in addition, it also ensures the diversity of life through communication between the crews of different ships.

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

The flight will last 100-150 years. Slow acceleration with an acceleration of approximately a hundredth of the earth's over a period of ten years, tens of years of flight by inertia, and somewhat faster deceleration than acceleration. 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, turbulence in space, gaps in time - all these paraphernalia do not pose a threat due to their 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 having high energy and, therefore, high penetrating ability. On Earth, we are protected from them by the atmosphere and magnetic field; in space, if the flight is long, we must take special measures, shielding the living area of ​​the ship so that the dose of cosmic radiation does not greatly exceed the earthly level. A simple design technique will help here - fuel reserves (and they are very large) are located around the living compartments and shield them from radiation most of the flight time.

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

Several light years away

To indicate 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 whose speed 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, they previously 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 capable of traveling through space at the speed of light, such a journey would take many years. For earthlings, whose life expectancy is on average 80 years, this would be impossible. However, each species of living things has its own life cycle. For example, in California, USA, there are bristlecone pines that are already 5000 years old.

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

Shortest paths

It is likely that aliens 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 - the shortest paths between celestial bodies located at different ends of the Universe.