At some point in life each of us asked this question: how long to fly to the stars? Can I get a flight in one human lifetime, will such flights become the norm of everyday life? On this complex issue very many answers, depending on who you ask. Some simple, others more complicated. To find a comprehensive answer, too many things need to take into account.
Unfortunately, there are no real estimates, which would help to find this answer, does not exist, and it’s frustrating futurists and enthusiasts of interstellar travel. Whether we like it or not, the space is very large (and complex), and our technology is still limited. But if we ever decide to leave the “native nest”, we will have several ways to get to the nearest star systems in our galaxy.
The nearest star to Earth is the Sun, quite “average” star on “main sequence” of Hertzsprung – Russell. This means that the star is very stable and provides enough sunlight to our planet developed life. We know that around stars near our Solar system and other planets revolve, and many of these stars are similar to our own.
Possible habitable worlds in the Universe
In the future, if humanity wishes to leave the Solar system, we will have a huge choice of stars we could go, and many of them may have favorable living conditions. But where do we go and how much time we will take the road there? Don’t forget that all this is just speculation, and there are no reference points for interstellar travel now. Well, as said Gagarin, go!
Reach for the stars
As already noted, the nearest star to our Solar system is Proxima Centauri, and therefore makes a lot of sense to start planning for an interstellar mission with her. Being part of a triple star system alpha Centauri, Proxima is a 4.24 light years (1.3 parsecs) from Earth. Alpha Centauri is, in fact, the brightest star of three in the system, part of a close binary system in to 4.37 light years from the Earth whereas alpha Centauri (the most dull of the three) is an isolated red dwarf in a 0.13 light years from the binary system.
And although conversations about interstellar travel evoke thoughts about all sorts of traveling “faster than light” (SVB), starting from warp speed to wormholes and subspace engines, such theory or highly are fictional (like the engine Alcubierre), or exist only in science fiction. Any mission into deep space will last for generations.
So, if you start with one of the slowest forms of space travel, how long will it take to get to Proxima Centauri?
Modern methods
The question of duration of displacement in space is much easier if it involved existing technologies and bodies in our Solar system. For example, using technology to support the mission “New horizons”, 16 engines, the hydrazine powered monotopia, you can get to the moon in just 8 hours and 35 minutes.
There are also mission SMART-1 European space Agency, which moved to the moon using ion thrust. With this revolutionary technology, which also used the space probe Dawn to reach Vesta, mission SMART-1 has taken a year, a month and two weeks to get to the moon.
From quick rocket and spacecraft to the economical ion engine, we have a couple of options of transportation around the local space — plus you can use Jupiter or Saturn as a gravitational slingshot is huge. However, if we plan to get out a little farther, we have to increase the power technologies and explore new opportunities.
When we talk about possible methods, we are talking about those that involve existing technologies, or those that do not yet exist, but which is technically feasible. Some of them, as you will see, time-tested and proven, while others remain in question. In short, they represent a possible but very time-consuming and Finance scenario travel even to the nearest star.
Ion movement
Now the slowest and most economical form of engine is the ion engine. A few decades ago, the ion motion was considered science fiction. But in recent years technology support ion propulsion has moved from theory to practice, and very successfully. The mission SMART-1 European space Agency’s successful mission to the moon within 13 months of spiral motion from the Ground.
SMART-1 used ion engines to solar energy, in which electricity was about solar panels and used to power the Hall effect. To deliver SMART-1 to the moon, it took just 82 kilograms of xenon fuel. 1 kg of xenon fuel provides the Delta-V of 45 m/s. It is a highly effective form of movement, but not the fastest.
One of the first missions to use ion engine technology was Deep Space 1 mission to comet Borrelli in 1998. DS1 also used a xenon ion engine and spent 81,5 kg of fuel. For 20 months, DS1 has developed a traction speed of 56,000 km/h at the time of the passage of the comet.
Ion engines are more economical than rocket technology as their thrust per unit mass of propellant (specific impulse) is far higher. But ion engines need a lot of time to accelerate the spacecraft to significant speeds, and maximum speed depends on the fuel support and the electric power output.
So, if you use ion movement in the mission to Proxima Centauri, the engines need to have a powerful source of energy (nuclear energy) and large reserves of fuel (although less than normal missiles). But if you start from the assumption that to 81.5 kg of xenon fuel is translated into 56 000 km/h (and there will be no other forms of movement), can be estimated.
At a maximum speed of 56 000 km/h in Deep Space would 1 000 81 years to overcome a 4.24 light years between Earth and alpha Centauri. Time is of the order of 2700 generations of people. We can confidently say that interplanetary ion engine will be too slow for manned interstellar mission.
But if ion engines will be larger and more powerful than (that is, the speed of the Exodus of ions will be much higher), if there is enough rocket fuel to last all 4,24 light years, time travel will be significantly reduced. But will still be significantly longer human life.
Gravity-assist maneuver
The fastest method of space travel is the use of gravity maneuver. This method includes the use of spacecraft relative motion (i.e. orbit) and the planets gravity to change the path and speed. Gravity maneuvers are very useful technique of space flight, particularly when using the Earth or other massive planets (like gas giants) to accelerate.
The spacecraft Mariner 10 was the first to employ this method, using the gravitational pull of Venus to disperse in the direction of mercury in February 1974. In the 1980s the probe “Voyager-1” used Saturn and Jupiter for gravitational maneuvers, and acceleration to 60 000 km/h with the subsequent release into interstellar space.
The mission of Helios 2, which began in 1976 and was to investigate the interplanetary medium between 0.3 a. E. and 1 and. that is from the Sun, holds the record highest speed, developed through a gravitational maneuver. At that time, Helios 1 (launched in 1974) and Helios 2 has held the record the nearest approach to the Sun. Helios 2 was launched on a conventional rocket and launched on a highly elongated orbit.
Due to the large eccentricity (0,54) 190-day solar orbit, at perihelion Helios 2 was able to reach a top speed of 240,000 km/h. This orbital speed was developed due to the only gravitational attraction of the Sun. Technically the speed at perihelion Helios 2 was not the result of a gravitational maneuver, and the maximum orbital velocity, but the device still holds the record for being the fastest artificial object.
If “Voyager-1” was moving in the direction of the red dwarf Proxima Centauri with a constant speed of 60 000 km/h, he would have required 76 000 years (or 2500 generations) to overcome this distance. But if the probe has developed a record-speed of Helios 2 — constant speed of 240,000 km/h — it would take him 19 000 years (or over 600 generations) to overcome 4,243 light years. Significantly better, although not even close to practical.
Electromagnetic motor Drive EM
Another suggested method of interstellar travel is the RF engine with a resonant cavity, also known as EM Drive. I proposed back in 2001, Roger Scheuer, of the British scientists who created the Satellite Propulsion Research Ltd (SPR) for the implementation of the project, the engine based on the idea that electromagnetic microwave cavity can directly convert electricity into thrust.
If traditional electromagnetic motors are designed to propel a given mass (like ionized particles), specifically this propulsion system does not depend on the reaction mass and does not emit directional radiation. In General, this engine met with considerable 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 change under the action of forces.
However, recent experiments with this technology has apparently led to positive results. In July 2014, on the 50th conference AIAA/ASME/SAE/ASEE Joint Propulsion Conference in Cleveland, Ohio, NASA scientists involved with advanced rocket development, said that it had successfully tested a new design of an electromagnetic engine.
In April 2015 scientists at NASA Eagleworks (part of the Space center. Johnson) stated that it had successfully tested this engine in a vacuum that may indicate possible use in space. In July of the same year, a group of scientists from the Department of space systems Dresden University of technology has developed its own version of the engine and watched tangible traction.
In 2010, Professor Chuang Yang from northwestern Polytechnic University in Xian, China, began to publish a series of articles about their research technologies EM Drive. In 2012 it announced high input power (2.5 kW) and fixed in a thrust of 720 mn. In 2014 she has also conducted extensive tests, including measurements of internal temperatures with embedded thermocouples showed that the system works.
According to calculations based on the NASA prototype (which was given the power rating of 0.4 N/kW), spacecraft on the electromagnetic motor can travel to Pluto in less than 18 months. This is six times less than it took to probe “New horizons”, which was moving at a speed of 58,000 km/h.
Sounds impressive. But even in this case, the ship’s electromagnetic motors will fly to Proxima Centauri 13 000 years. Close, but still not enough. In addition, while this technology will not placed all points over e, too early to speak about its use.
Nuclear thermal and nuclear electric movement
Another possibility to make interstellar flights — use a spacecraft, equipped with nuclear engines. NASA for decades has studied such options. In the rocket in a nuclear thermal motion could be used or deuterium uranium reactors to heat hydrogen in a reactor, turning it into ionized gas (plasma of hydrogen), which then will be heading to the rocket nozzle, generating thrust.
The rocket with a nuclear electric drive includes the same reactor, which converts heat and energy into electricity, which then feeds the motor. In both cases, the missile would rely on nuclear fusion or nuclear fission to create thrust, instead of chemical fuel, which employs all the modern space Agency.
Compared with chemical engines, nuclear has obvious advantages. First, it’s virtually unlimited energy density than rocket fuel. In addition, the nuclear engine will also produce powerful traction compared to the used amount of fuel. This will reduce the amount of required fuel, thus the weight and cost of a particular apparatus.
Although the engines thermal nuclear energy while in space were, their prototypes were created and tested, and offered them more.
And yet, despite the advantages in fuel economy and specific impulse, the best of the proposed concepts nuclear thermal engine has a maximum specific impulse of 5000 seconds (50 kN·s/kg). Using nuclear engines, nuclear fission and fusion, scientists at NASA could bring the spacecraft to Mars in just 90 days, if the Red planet will be 55 000 000 kilometres from Earth.
But if we talk about the journey to Proxima Centauri, the nuclear rocket will take ages to accelerate to a significant fraction of the speed of light. Then you’ll need a few decades the way, and behind them many centuries of braking on the way to the goal. We are still 1000 years away from your destination. Good for interplanetary missions, not so good for interstellar.