Light year and cosmic scales. What is the safe distance between us and the supernova? To the outskirts of the universe

Proxima Centauri.

Here's a classic backfill question. Ask your friends, " Which one is the closest to us?"and then watch how they list nearby stars... Maybe Sirius? Alpha is there something? Betelgeuse? The obvious answer is this; a massive ball of plasma located about 150 million kilometers from Earth. Let's clarify the question. Which star is closest to the Sun?

Nearest star

You've probably heard that it is the third brightest star in the sky at a distance of only 4.37 light years from. But Alpha Centauri not a single star, it is a system of three stars. First, a double star (binary star) with a common center of gravity and an orbital period of 80 years. Alpha Centauri A is only slightly more massive and brighter than the Sun, and Alpha Centauri B is slightly less massive than the Sun. This system also contains a third component, a dull red dwarf Proxima Centauri.

Proxima Centauri- That's what it is the closest star to our sun located at a distance of only 4.24 light years.

Proxima Centauri.

Multiple star system Alpha Centauri located in the constellation Centaurus, which is visible only in the southern hemisphere. Unfortunately, even if you see this system, you will not be able to see Proximu Centauri... This star is so faint that you will need a powerful enough telescope to see it.

Let's figure out the scale of how far Proxima Centauri from U.S. Think about. moves at a speed of nearly 60,000 km / h, the fastest in. He covered this path in 2015 in 9 years. Traveling fast enough to get to Proxima Centauri, New Horizons will take 78,000 light years.

Proxima Centauri is the closest star over 32,000 light years, and it will hold this record for another 33,000 years. It will make its closest approach to the Sun in about 26,700 years, when the distance from this star to Earth is only 3.11 light years. In 33,000 years, the nearest star will be Ross 248.

What about the northern hemisphere?

For those of us in the northern hemisphere, the closest visible star is Barnard's Star, another red dwarf in the constellation Ophiuchus. Unfortunately, like Proxima Centauri, Barnard's Star is too dim to see with the naked eye.

Barnard's Star.

Nearest star that you can see with the naked eye in the northern hemisphere is Sirius (Alpha Canis Major)... Sirius is twice the size and mass of the Sun, and is the brightest star in the sky. Located 8.6 light-years away in the constellation Canis Major, it is the most famous star that stalks Orion in the night sky in winter.

How did astronomers measure the distance to the stars?

They use a method called. Let's do a little experiment. Keep one arm outstretched and place your finger so that there is some distant object nearby. Now open and close each eye in turn. Notice how your finger seems to jump back and forth when you look with different eyes. This is the parallax method.

Parallax.

To measure the distance to the stars, you can measure the angle to the star in relation to when the Earth is on one side of the orbit, say in the summer, then 6 months later, when the Earth moves to the opposite side of the orbit, and then measure the angle to the star relative to what - any distant object. If the star is close to us, this angle can be measured and the distance calculated.

You can actually measure the distance in this way up to nearest stars but this method only works up to 100 "000 light years.

20 closest stars

Here is a list of the 20 closest star systems and their distance in light years. Some of them have multiple stars, but they are part of the same system.

According to NASA, there are 45 stars within a 17 light-year radius of the Sun. There are over 200 billion stars in the world. Some are so dim that they are nearly impossible to detect. Perhaps with new technologies, scientists will find stars even closer to us.

Title of the article you read "The closest star to the Sun".

On February 22, 2017, NASA reported that 7 exoplanets were found near the single TRAPPIST-1 star. Three of them are in the range of distances from the star in which the planet can have liquid water, and water is a key condition for life. It is also reported that this star system is located at a distance of 40 light-years from Earth.

This message caused a lot of noise in the media, it even seemed to some that humanity is on the verge of building new settlements near a new star, but this is not so. But 40 light years is a lot, it is a LOT, it is too many kilometers, that is, this is a monstrously colossal distance!

From the physics course, the third cosmic speed is known - this is the speed that a body must have at the surface of the Earth in order to go beyond the solar system. The value of this speed is 16.65 km / s. Orbital spacecraft take off at a speed of 7.9 km / sec and revolve around the Earth. In principle, a speed of 16-20 km / s is quite accessible to modern earthly technologies, but no more!

Humanity has not yet learned how to accelerate spacecraft faster than 20 km / sec.

Let's calculate how many years it will take for a starship traveling at a speed of 20 km / s to travel 40 light years and reach the star TRAPPIST-1.
One light year is the distance that a ray of light travels in a vacuum, and the speed of light is approximately 300 thousand km / sec.

A spaceship, made by human hands, flies at a speed of 20 km / sec, that is, 15,000 times slower than the speed of light. Such a ship will cover 40 light years in a time equal to 40 * 15000 = 600000 years!

An earth ship (with the current level of technology) will reach the TRAPPIST-1 star in about 600 thousand years! Homo sapiens has existed on Earth (according to scientists) only 35-40 thousand years, and here it is as much as 600 thousand years!

In the near future, technology will not allow a person to reach the TRAPPIST-1 star. Even promising engines (ionic, photonic, space sails, etc.), which do not exist in earthly reality, are estimated to be able to accelerate the ship to a speed of 10,000 km / s, which means that the flight time to the TRAPPIST-1 system will be reduced to 120 years. ... This is already a more or less acceptable time for flying with the help of suspended animation or for several generations of settlers, but today all these engines are fantastic.

Even the nearest stars are still too far from people, too far, not to mention the stars of our Galaxy or other galaxies.

The diameter of our Milky Way galaxy is about 100 thousand light years, that is, the path from end to end for a modern Earth ship will be 1.5 billion years! Science suggests that our Earth is 4.5 billion years old, and multicellular life is about 2 billion years old. The distance to the nearest galaxy to us - the Andromeda Nebula - is 2.5 million light years from Earth - what a monstrous distance!

As you can see, of all living people, no one will ever set foot on the earth of a planet near another star.

Due to the annual motion of the Earth in its orbit, nearby stars move slightly relative to distant "fixed" stars. For a year, such a star describes a small ellipse in the celestial sphere, the size of which is the smaller the further the star is. In angular measure, the semi-major axis of this ellipse is approximately equal to the value of the maximum angle at which 1 AU is visible from the star. e. (semi-major axis of the earth's orbit), perpendicular to the direction of the star. This angle (), called the annual or trigonometric parallax of the star, equal to half of its apparent displacement per year, is used to measure the distance to it based on trigonometric ratios between the sides and angles of the ZSA triangle, in which the angle and basis are known - the semi-major axis of the earth's orbit (cm Fig. 1).

Figure 1. Determination of the distance to the star by the parallax method (A - star, W - Earth, C - Sun).

Distance r to the star, determined by the magnitude of its trigonometric parallax, is equal to:

r = 206265 "" / (a.u.),

where parallax is expressed in arc seconds.

For the convenience of determining distances to stars using parallaxes, a special unit of length is used in astronomy - parsec (ps). A star located at a distance of 1 ps has a parallax of 1 "". According to the above formula, 1 ps = 206265 amu. e. = 3.086 10 18 cm.

Along with the parsec, another special unit of distance is used - a light year (that is, the distance that light travels in 1 year), it is equal to 0.307 ps, or 9.46 10 17 cm.

The closest star to the Solar System - a red dwarf of 12th magnitude Proxima Centauri - has a parallax of 0.762, i.e., the distance to it is 1.31 ps (4.3 light years).

The lower limit of measurement of trigonometric parallaxes is ~ 0.01 "", so they can be used to measure distances not exceeding 100 ps with a relative error of 50%. (At distances up to 20 ps, ​​the relative error does not exceed 10%.) This method has so far been used to determine distances up to about 6000 stars. Distances to more distant stars in astronomy are determined mainly by the photometric method.

Table 1. Twenty nearest stars.

Stars are the most common type of celestial body in the universe. There are about 6000 stars up to 6th magnitude, about a million up to 11th magnitude, and up to 21st magnitude, there are about 2 billion stars in the entire sky.

All of them, like the Sun, are hot self-luminous balls of gas, in the depths of which enormous energy is released. However, stars, even in the strongest telescopes, are visible as points of light, since they are very far from us.

1. Yearly parallax and distances to stars

The radius of the Earth turns out to be too small to serve as a basis for measuring the parallax displacement of stars and for determining the distances to them. Even in the days of Copernicus, it was clear that if the Earth really revolves around the Sun, then the apparent positions of the stars in the sky must change. For six months, the Earth moves by the size of the diameter of its orbit. The directions to the star from opposite points of this orbit should be different. In other words, the stars should have a noticeable annual parallax (Fig. 72).

The annual parallax of the star ρ is the angle at which from the star one could see the semi-major axis of the earth's orbit (equal to 1 AU) if it is perpendicular to the line of sight.

The greater the distance D to the star, the smaller its parallax. The parallactic displacement of the position of the star in the sky during the year occurs along a small ellipse or circle if the star is at the pole of the ecliptic (see Fig. 72).

Copernicus tried but failed to detect the parallax of the stars. He correctly asserted that the stars are too far from the Earth to be able to detect their parallax displacement with the instruments that existed at that time.

For the first time, a reliable measurement of the annual parallax of the Vega star was carried out in 1837 by the Russian academician V. Ya. Struve. Almost simultaneously with it, parallaxes were determined in other countries in two more stars, one of which was α Centauri. This star, which is not visible in the USSR, turned out to be the closest one to us, its annual parallax ρ = 0.75 ". At this angle, the naked eye can see a wire 1 mm thick from a distance of 280 m. small angular displacements.

Distance to the star where a is the semi-major axis of the earth's orbit. At small angles if p is in arc seconds. Then, taking a = 1 a. That is, we get:

Distance to the nearest star α Centauri D = 206 265 ": 0.75" = 270 000 AU. e. Light travels this distance in 4 years, while it takes only 8 minutes from the Sun to the Earth, and about 1 second from the Moon.

The distance that light travels in a year is called a light year.... This unit is used to measure distance along with parsec (pc).

Parsec is the distance from which the semi-major axis of the Earth's orbit, perpendicular to the line of sight, is seen at an angle of 1 ".

The distance in parsecs is equal to the reciprocal of the annual parallax, expressed in arc seconds. For example, the distance to the star α Centauri is 0.75 "(3/4"), or 4/3 pc.

1 parsec = 3.26 light years = 206 265 amu. e. = 3 * 10 13 km.

At present, the measurement of the annual parallax is the main method for determining the distances to stars. Parallaxes have already been measured for many stars.

By measuring the annual parallax, it is possible to reliably establish the distance to stars within 100 pc, or 300 light years.

Why is it not possible to accurately measure the annual parallax of more than o distant stars?

Distances to more distant stars are currently being determined by other methods (see §25.1).

2. Visible and absolute magnitude

The luminosity of the stars. After astronomers were able to determine the distance to stars, it was found that stars differ in apparent brightness, not only because of the difference in distance to them, but also because of their difference. luminosity.

The luminosity of a star L is the power of emission of light energy in comparison with the power of emission of light by the Sun.

If two stars have the same luminosity, then the star that is farther from us has a lower apparent brightness. It is possible to compare stars in luminosity only if their apparent brightness (magnitude) is calculated for the same standard distance. Such a distance in astronomy is considered to be 10 pc.

The apparent stellar magnitude that a star would have if it were at the standard distance D 0 = 10 pc is called the absolute stellar magnitude M.

Let us consider the quantitative ratio of the apparent and absolute stellar magnitudes of a star at a known distance D to it (or its parallax p). Let us first recall that a difference of 5 magnitudes corresponds to a brightness difference of exactly 100 times. Consequently, the difference between the apparent magnitudes of two sources is equal to unity when one of them is exactly one times brighter than the other (this value is approximately equal to 2.512). The brighter the source, the smaller its apparent magnitude is. In the general case, the ratio of the apparent brightness of any two stars I 1: I 2 is associated with the difference between their apparent magnitudes m 1 and m 2 by a simple relationship:

Let m be the apparent magnitude of a star located at a distance D. If it were observed from a distance of D 0 = 10 pc, its apparent magnitude m 0, by definition, would be equal to the absolute magnitude M. Then its apparent brightness would change into

At the same time, it is known that the apparent brightness of a star changes in inverse proportion to the square of the distance to it. That's why

(2)

Hence,

(3)

Taking the logarithm of this expression, we find:

(4)

where p is in arc seconds.

These formulas give the absolute magnitude M according to the known apparent magnitude m at a real distance to the star D. Our Sun from a distance of 10 pc would look approximately like a star of the 5th apparent magnitude, i.e., M ≈ 5 for the Sun.

Knowing the absolute magnitude M of some star, it is easy to calculate its luminosity L. Taking the luminosity of the Sun L = 1, by definition of the luminosity, we can write that

The quantities M and L in different units express the radiation power of the star.

The study of stars shows that they can differ in luminosity by tens of billions of times. In magnitudes, this difference reaches 26 units.

Absolute values stars of very high luminosity are negative and reach M = -9. Such stars are called giants and supergiants. The radiation of the star S Doradus is 500,000 times more powerful than the radiation of our Sun, its luminosity is L = 500,000, the dwarfs with M = + 17 (L = 0.000013) have the lowest radiation power.

To understand the reasons for the significant differences in the luminosity of stars, it is necessary to consider their other characteristics, which can be determined based on the analysis of radiation.

3. Color, spectra and temperature of stars

During the observations, you noticed that the stars have a different color, which is clearly visible in the brightest of them. The color of the heated body, including the star, depends on its temperature. This makes it possible to determine the temperature of stars from the distribution of energy in their continuous spectrum.

The color and spectrum of stars are related to their temperature. Relatively cool stars are dominated by radiation in the red region of the spectrum, which is why they have a reddish color. The temperature of the red stars is low. It grows sequentially from red stars to orange, then yellow, yellowish, white and bluish. The spectra of stars are extremely diverse. They are divided into classes denoted by Latin letters and numbers (see back endpaper). In the spectra of cool red M class stars with a temperature of about 3000 K, absorption bands of the simplest diatomic molecules, most often titanium oxide, are visible. The spectra of other red stars are dominated by oxides of carbon or zirconium. Red stars of the first magnitude class M - Antares, Betelgeuse.

In the spectra of yellow class G stars To which the Sun belongs (with a temperature of 6000 K on the surface), thin lines of metals predominate: iron, calcium, sodium, etc. A star of the Sun type in spectrum, color and temperature is the bright Capella in the constellation Auriga.

In the spectra of class A white stars like Sirius, Vega and Deneb, the hydrogen lines are strongest. There are many weak lines of ionized metals. The temperature of such stars is about 10,000 K.

In the spectra of the hottest, bluish stars with a temperature of about 30,000 K, lines of neutral and ionized helium are visible.

Most stars have temperatures ranging from 3,000 to 30,000 K. Few stars have temperatures around 100,000 K.

Thus, the spectra of stars are very different from each other and from them it is possible to determine the chemical composition and temperature of the atmospheres of stars. The study of the spectra showed that hydrogen and helium are predominant in the atmospheres of all stars.

The differences in stellar spectra are explained not so much by the diversity of their chemical composition as by the difference in temperature and other physical conditions in stellar atmospheres. At high temperatures, molecules are broken down into atoms. At an even higher temperature, less durable atoms are destroyed, they turn into ions, losing electrons. Ionized atoms of many chemical elements, like neutral atoms, emit and absorb energy at specific wavelengths. By comparing the intensities of the absorption lines of atoms and ions of the same chemical element, their relative amount is theoretically determined. It is a function of temperature. Thus, the dark lines of the spectra of stars can be used to determine the temperature of their atmospheres.

Stars have the same temperature and color, but different luminosities, the spectra are generally the same, but you can notice differences in the relative intensities of some lines. This is due to the fact that at the same temperature, the pressure in their atmospheres is different. For example, in the atmospheres of giant stars, the pressure is less, they are more rarefied. If we express this dependence graphically, then the intensity of the lines can be used to find the absolute magnitude of the star, and then, using formula (4), determine the distance to it.

An example of solving the problem

Task. What is the luminosity of the star ζ Scorpio, if its apparent magnitude is 3, and the distance to it is 7500 ns. years?

Exercise # 20

1. How many times is Sirius brighter than Aldebaran? Is the sun brighter than Sirius?

2. One star is 16 times brighter than the other. What is the difference between their magnitudes?

3. Parallax Vega 0.11 ". How long does the light travel from it to the Earth?

4. How many years would it take to fly towards the constellation Lyra at a speed of 30 km / s for Vega to become twice as close?

5. How many times is a star of 3.4 magnitude fainter than Sirius, which has an apparent magnitude of -1.6? What are the absolute magnitudes of these stars if the distance to both is 3 pc?

6. Name the color of each of the stars in Appendix IV according to their spectral class.

At some point in our lives, each of us asked this question: how long to fly to the stars? Is it possible to carry out such a flight in one human life, can such flights become the norm of everyday life? There are many answers to this difficult question, depending on who is asking. Some are simple, others are more difficult. To find a definitive answer, there is too much to take into account.

Unfortunately, no real estimates exist that would help find such an answer, and this is frustrating for futurists and interstellar travel enthusiasts. Whether we like it or not, space is very large (and complex) and our technology is still limited. But if we ever decide to leave our "home nest", we will have several ways to get to the nearest star system in our galaxy.

The closest star to our Earth is the Sun, quite an "average" star according to the Hertzsprung-Russell "main sequence" scheme. This means that the star is very stable and provides enough sunlight for life to develop on our planet. We know that there are other planets orbiting the stars near our solar system, and many of these stars are similar to our own.

In the future, if humanity wants to leave the solar system, we will have a huge selection of stars that we could get to, and many of them may well have favorable conditions for life. But where are we going and how long will it take us to get there? Keep in mind that this is all speculation and there are no landmarks for interstellar travel at this time. Well, as Gagarin said, let's go!

Reach for the star
As already noted, the closest star to our solar system is Proxima Centauri, and therefore it makes a lot of sense to start planning an interstellar mission with it. Part of the Alpha Centauri triple star system, Proxima is 4.24 light years (1.3 parsecs) from Earth. Alpha Centauri is essentially the brightest star of the three in the system, part of a close binary system 4.37 light years from Earth - while Proxima Centauri (the faintest of the three) is an isolated red dwarf 0.13 light years away. from a dual system.

And while conversations about interstellar travel inspire thoughts of all kinds of faster-than-light (FAS) travel, from warp speeds to wormholes to subspace engines, such theories are either highly fictional (like the Alcubierre engine) or only exist in science fiction. ... Any mission to deep space will stretch over generations of people.

So, starting with one of the slowest forms of space travel, how long does it take to get to Proxima Centauri?

Modern methods

The question of estimating the duration of travel in space is much easier if existing technologies and bodies in our solar system are involved in it. For example, using the technology used by the New Horizons mission, 16 hydrazine monofuel engines, you can reach the Moon in just 8 hours and 35 minutes.

There is also the European Space Agency's SMART-1 mission, which was propelled towards the moon using ion thrust. With this revolutionary technology, a variant of which the Dawn space probe also used to reach Vesta, the SMART-1 mission took a year, a month and two weeks to reach the moon.

From a fast rocket spacecraft to an economical ion drive, we have a couple of options for getting around local space - plus you could use Jupiter or Saturn as a giant gravity slingshot. Nevertheless, if we plan to get a little further, we will have to build up the power of technology and explore new possibilities.

When we talk about possible methods, we are talking about those that involve existing technologies, or those that do not yet exist, but which are technically feasible. Some of them, as you will see, are time-tested and confirmed, while others are still in question. In short, they represent a possible, but very time-consuming and costly scenario of traveling even to the nearest star.

Ionic movement

Currently, the slowest and most economical form of engine is the ion engine. Several decades ago, ion propulsion was considered the subject of science fiction. But in recent years, ion propulsion support technologies have moved from theory to practice, and with great success. The European Space Agency's SMART-1 mission is an example of a successful mission to the Moon in 13 months of spiral motion from Earth.

SMART-1 used solar-powered ion thrusters, in which electricity was collected by solar panels and used to power Hall effect thrusters. It took only 82 kilograms of xenon fuel to get SMART-1 to the moon. 1 kilogram of xenon fuel provides a delta-V of 45 m / s. This is an extremely effective form of movement, but far from the fastest.

One of the first missions to use ion propulsion technology was the Deep Space 1 mission to Comet Borrelli in 1998. The DS1 also used a xenon ion engine and consumed 81.5 kg of fuel. For 20 months of thrust, DS1 developed speeds of 56,000 km / h at the time of the comet's passage.

Ion engines are more economical than rocket technologies because their thrust per unit mass of propellant (specific impulse) is much higher. But ion thrusters take a long time to accelerate a spacecraft to significant speeds, and top speed depends on fuel support and power generation.

Therefore, if ion propulsion is used in a mission to Proxima Centauri, the engines must have a powerful source of energy (nuclear power) and large reserves of fuel (although less than conventional rockets). But if we start from the assumption that 81.5 kg of xenon fuel translates into 56,000 km / h (and there will be no other forms of movement), calculations can be made.

At a top speed of 56,000 km / h, Deep Space 1 would take 81,000 years to travel 4.24 light years between Earth and Proxima Centauri. In time, this is about 2700 generations of people. It's safe to say that an interplanetary ion drive will be too slow for a manned interstellar mission.

But if the ion thrusters are larger and more powerful (that is, the rate of exit of the ions will be significantly higher), if there is enough rocket fuel, which is enough for the entire 4.24 light years, travel time will be significantly reduced. But all the same there will be much longer than the period of human life.

Gravity maneuver

The fastest way to travel in space is to use gravity assist. This method involves the spacecraft using the relative motion (i.e. orbit) and gravity of the planet to alter its path and speed. Gravitational maneuvers are an extremely useful technique for space travel, especially when using Earth or another massive planet (like a gas giant) for acceleration.

The Mariner 10 spacecraft was the first to use this method, using the gravitational pull of Venus to accelerate toward Mercury in February 1974. In the 1980s, the Voyager 1 probe used Saturn and Jupiter for gravitational maneuvers and acceleration to 60,000 km / h, followed by an exit into interstellar space.

The Helios 2 mission, which began in 1976 and was supposed to explore the interplanetary medium between 0.3 AU. e. and 1 a. That is, from the Sun, holds the record for the highest speed developed using a gravity assist maneuver. At that time, Helios 1 (launched in 1974) and Helios 2 held the record for the closest approach to the Sun. Helios 2 was launched by a conventional rocket and put into a highly elongated orbit.

Due to the large eccentricity (0.54) of the 190-day solar orbit, at perihelion Helios 2 managed to reach a maximum speed of over 240,000 km / h. This orbital speed was developed only by the gravitational attraction of the Sun. Technically, the perihelion speed of Helios 2 was not the result of gravitational maneuver, but the maximum orbital speed, but the device still holds the record for the fastest artificial object.

If Voyager 1 was moving towards the red dwarf Proxima Centauri at a constant speed of 60,000 km / h, it would take 76,000 years (or more than 2,500 generations) to cover that distance. But if the probe were to reach the record speed of Helios 2 - a constant speed of 240,000 km / h - it would take 19,000 years (or more than 600 generations) to travel 4,243 light years. Much better, although not nearly practical.

Electromagnetic motor EM Drive

Another proposed method for interstellar travel is a resonant cavity radio frequency motor, also known as EM Drive. Proposed back in 2001 by Roger Scheuer, a British scientist who created Satellite Propulsion Research Ltd (SPR) to implement the project, the engine is based on the idea that electromagnetic microwave cavities can directly convert electricity into thrust.

Whereas traditional electromagnetic motors are designed to propel a specific mass (such as ionized particles), this particular propulsion system does not depend on the reaction of the mass and does not emit directional radiation. In general, this engine was greeted with a fair amount of skepticism largely because it violates the law of conservation of momentum, according to which the momentum of the system remains constant and cannot be created or destroyed, but only changed under the action of force.

Nevertheless, recent experiments with this technology have clearly led to positive results. In July 2014, at the 50th AIAA / ASME / SAE / ASEE Joint Propulsion Conference in Cleveland, Ohio, NASA's advanced jet scientists announced that they had successfully tested a new electromagnetic motor design.

In April 2015, scientists at NASA Eagleworks (part of the Johnson Space Center) said they had successfully tested the engine in a vacuum, which could indicate a possible use in space. In July of the same year, a group of scientists from the space systems department of the Dresden University of Technology developed their own version of the engine and observed tangible thrust.

In 2010, Professor Zhuang Yang of Northwestern Polytechnic University in Xi'an, China, began publishing a series of articles about her research on EM Drive technology. In 2012, it reported a high input power (2.5 kW) and a fixed thrust of 720 mn. In 2014, she also performed extensive tests, including internal temperature measurements with built-in thermocouples, which showed that the system was working.

According to calculations based on the NASA prototype (which was given a power rating of 0.4 N / kilowatt), an electromagnetic-powered spacecraft could make a trip to Pluto in less than 18 months. This is six times less than what was required by the New Horizons probe, which was moving at a speed of 58,000 km / h.

Sounds impressive. But even in this case, the ship on electromagnetic engines will fly to Proxima Centauri for 13,000 years. Close, but still not enough. In addition, until all points are dotted over it in this technology, it is too early to talk about its use.

Nuclear thermal and nuclear electric propulsion

Another possibility to carry out an interstellar flight is to use a spacecraft equipped with nuclear engines. NASA has studied such options for decades. A nuclear thermal propulsion rocket could use uranium or deuterium reactors to heat hydrogen in the reactor, converting it into ionized gas (hydrogen plasma), which would then be directed into the rocket nozzle, generating thrust.

A nuclear-powered rocket includes the same reactor that converts heat and energy into electricity, which then powers the electric motor. In both cases, the rocket will rely on nuclear fusion or nuclear fission to generate thrust, rather than the chemical fuel that all modern space agencies operate on.

Compared to chemical engines, nuclear engines have undeniable advantages. Firstly, it is practically unlimited energy density compared to rocket fuel. In addition, the nuclear engine will also generate powerful thrust relative to the amount of fuel being used. This will reduce the amount of fuel required, and at the same time the weight and cost of a particular apparatus.

Although thermal nuclear power engines have not yet entered space, their prototypes have been created and tested, and even more have been proposed.

And yet, despite the advantages in fuel economy and specific impulse, the best proposed nuclear thermal engine concept has a maximum specific impulse of 5000 seconds (50 kN · s / kg). Using nuclear engines powered by nuclear fission or fusion, NASA scientists could deliver a spacecraft to Mars in just 90 days if the Red Planet is 55,000,000 kilometers from Earth.

But when it comes to traveling to Proxima Centauri, a nuclear rocket will take centuries to accelerate to a substantial fraction of the speed of light. Then it will take several decades of the way, and after them many more centuries of inhibition on the way to the goal. We are still 1000 years from our destination. What's good for interplanetary missions, not so good for interstellar missions.