the distances in the universe are enormous even Within the solar system it takes light a few hours to reach the outer planets, but to cross the distance between the stars it takes many years the most advanced spacecraft available to mankind will spend tens of thousands of years on its way to the nearest star it might seem that the conquest of new worlds forever remains the destiny of dreamers, but is this in fact the case the space first of all planets of the solar system Mars is the most suitable for exploration periodically it comes close to which is just under 56 million km light and radio waves pass it in 3 minutes but spacecrafts need much more time to do this they have to travel through the solar system on complex trajectories using gravity maneuvers near other planets e.g. the Mars rover Perseverance traveled to the red planet for just under 7 months it is expected that the spacex starship can significantly reduce this time but no concrete data on the duration of the planned Martian expedition is available yet. Even light, travelling to other stars is even more complicated, with its speed of just under 300 000 km per second, travels to the nearest star like Cosima Centauri for over four years. The same flight with the most modern spacecraft would take about 40 000 years but even this incredible figure is too optimistic as the rockets are not powerful enough, even with some cunning gravitational maneuvers the speed needed to overcome the sun's gravity and have minimum chance to reach other stellar systems is unfortunately something humanity can only dream about. the fastest spacecraft at the moment is the unmanned solar the Parker umbrella, launched by nasa in 2018 in april this year, its speed reached 147 kilometers per second and after a series of gravitational maneuvers planned for the coming years the zone will be able to accelerate to 194 kilometers per second, or around 700 thousand kilometers per hour however most spacecrafts move no faster than 11 kilometers per second, which is enough to put an object in orbit around the Earth or even reach the moon, but to travel to other objects in the solar system would require much more acceleration. Unfortunately, even with the most powerful modern engines, the flight would take very long. Automated probes and the next edges of our system spend decades in transit before reaching their destination Even the best modern rocket engines have some fundamental drawbacks, the useful mass is only a few percent of the circum and the specific impulse is close to technological limit If the objects of solar system at least in theory can be reached with their help then to fly to the stars we should search for other methods undoubtedly there are some fantastic sounding ways to increase speed of spacecrafts but others are actively applied now e.g. ion engines where charged particles are accelerated in electrostatic field giving their impulse to spacecrafts. they already show up to 70 times more effective than rocket engines unfortunately their power is not enough to lift a spacecraft on Earth but they are used successfully on satellites and orbital stations for maneuvering and orbit correction already in the seventies. another approach suggests to give up the idea of jet propulsion instead of using the light pressure a solar sail can accelerate a spacecraft up to hundreds of kilometers per second capturing flow of photons coming from our planet and making it possible to obtain speeds of hundred kilometers per second in a very practical way it is also possible to catch solar wind such a sail is called electric, but it is impossible to take off from the surface of the earth or any other planet using a sail. of course it is possible to use other types of propulsion to reach outer space, however this doesn't solve another problem: far from the Sun this type of engines is ineffective as photon flux density in interstellar space is much less than in the vicinity of the star, so it's extremely difficult to overcome interstellar distances using such ship. in addition sail building requires materials combining extreme strength and incredible lightness probably graphite films or other scientific developments will help accelerate creation of such super economic but not so powerful spaceships the result of this direction could be a photon starship in which a powerful light source is created directly in the focus of a huge parabolic mirror, unfortunately this concept is still a science fiction at the current stage of development it is impossible to create neither a mirror nor a powerful enough light source. it is also possible to use the force of nuclear decay to create traction according to the american project of the middle of the last century. the ship equipped with a pulse nuclear engine could reach alpha centauri during one hundred and thirty years its acceleration would be made by a chain of nuclear explosions with the power of about a kiloton each The shock wave reflected from a solid heat resistant account could easily take the spacecraft out of the Earth atmosphere and accelerate it to the incredible speed the main problems of this spacecraft type were radioactive contamination of the launch pad and difficulties In manufacturing the pushers were not easy to create a shield able to sustain a chain of nuclear explosions even if they are very powerful as a result development of pulse nuclear engine was recognized as unpromising and all research in the field was ceased. however this does not mean that it is impossible to use nuclear fission energy for space flights in the simplest nuclear reactor project hydrogen is pumped through the reactor core made of rods the heat emitted in the course of nuclear decay heats gas to high temperatures afterwards it is ejected through a nozzle accelerating the ship Such an engine is called a solid-phase engine which can be built at the current technological stage; however the specific impulse of a solid-phase nuclear reactor is at least twice as high as that of modern chemical engines the temperature of the reactor core cannot exceed 3000 degrees celsius due to If it's increased to about 25 thousands degrees Celsius the inside of reactor will turn into a cloud of red-hot radioactive plasma and its efficiency will increase by several tens of times such an engine is called a gas-phase engine and its usage will not only reduce time of a flight to Mars to some weeks, however keeping a glowing radioactive plasma requires complicated engineering solutions. No material can stop a plasma cloud with a temperature of tens of thousands of degrees. Only powerful electromagnetic fields with special configuration technologies are being developed right now to help achieve this. They are also needed to develop a more powerful drive based on fusion reaction does not need heavy elements, which are hard to access. hydrogen, the most common element in the Universe, is used instead. Besides, during thermonuclear reaction much more energy is released than during the decay of heavy elements according to calculations this engine type can accelerate spacecraft up to 10000 times more effectively than modern drives, so trips to the nearest stars may take much longer. a shorter time of only a few decades modification of this type of spacecraft is the hypothetical project of interstellar direct precision starship bas horde based on thermonuclear jet engine and, and the front part is a giant trap of matter during the motion the starship should collect the discharged hydrogen filling space to use it as fuel or working body at a certain speed the starship can extract as much gas in motion as it spends on acceleration it makes the starship bastard almost autonomous nevertheless all these types of engines are not able to reach even a tenth of light speed in the shortest time however the Mexican physicist Miguel Alcubierre, At the end of the last century he proposed an extremely bold hypothesis based on the following assumption: if it is impossible to move at superluminal speed in ordinary space, then it is possible to move space itself. According to al-kiber's hypothesis the hydraulic drive should compress space in the direction of movement and stretch it behind the ship for this purpose so called exotic matter with unusual properties such as negative energy density theoretically such matter may exist, but
Experimentally it has not yet been possible to detect it for a long time the courier hypothesis was not taken seriously primarily because of for a long time, the courier hypothesis was not taken seriously first of all because of the need of exotic matter and lack of experimental confirmations probably it would have remained unsubstantiated but the last months have brought two encouraging news one of them is that German astrophysicist Eric Lens developed a theory according to which to create al courier bubble no exotic matter is needed Lens suggested to form it with help of steady singular wave created with special plasma such special wave is called a salt tone and it is able to propagate to create such a disturbance in space does not require exotic matter but the energy required for this process is still too high. several dozens of jupiters would have to be annihilated before a starship could reach the proxima closest star to the solar system however Eric Lens says that the energy requirement could be reduced by a factor of 30-60 and he is working on calculations right now another news is that physicists Alexey Bobrik and Gianni Mortier of New York New York have adapted the theory of their Mexican colleague for subluminal velocities. the refusal to go beyond the speed of light removes a number of paradoxes and allows us to theoretically reach very high speeds in the future. as a result of these calculations, the amount of energy needed to create the bubble has dropped by several orders of magnitude, reaching a value equivalent to the mass of the earth. human progress is accelerating every day what seemed fantastic 10 years ago is now commonplace. these days, unlikely assumptions become valid prototypes and then part of everyday life, the stars are getting closer to us every day. Maybe we'll see man conquer new planets.