Intergalactic Travel - An Overview

This is a topic close to my heart and something I've been working on over the last month. I hope you enjoy it :)

The History of Intergalactic Travel and an Overview of Ideas for Intergalactic Travel

Humanity has been curious about the universe ever since we realized that there was a whole new void to be discovered out there. Defying gravity to escape the Earth’s atmosphere was once the biggest hurdle in intergalactic, or even, space travel. However, with the advancement of technology, the first rocket to be launched into space became a reality.

In 1957, on the 4th of October, the Soviet Union launched Sputnik 1, an artificial satellite, into space. On November 3rd of the same year, they launched a dog into space in Sputnik 2, and this spacecraft remained in orbit successfully for 7 days. The United States of America, then engaged in the Cold War with the Soviet Union, decided to join what was subsequently called the Space Race.

They launched the Explorer 1 successfully in 1958, followed by the failure of Explorer 2. In 1961, both countries had successfully launched a human into space – Yuri Gagarin in Vostok 1 and Alan Shephard by the United States. In 1962, the United States succeeded in sending John Glen into orbit, making him the first American to do so.

In 1969, the United States made history and imprinted their name in the realm of space travel by sending a man to the moon. This man was Neil Armstrong and he became the first man to walk on the moon. This was the first manned mission to another celestial body other than the Earth. Earlier, in 1959, Luna was the first artificial object that landed on another celestial body.

Ever since, there have been five more manned missions to the moon. However, no man has ventured into territory beyond the moon. Instead, we have had space probes, such as Voyager 1 and Voyager 2, launched in 1977, which only recently crossed through the border of our solar system in to interstellar space, which is the furthest that we have managed to reach so far.

There have been various theories proposing methods of intergalactic travel. These include hitchhiking rides on comets, using interstellar ramjets, nuclear fusion rockets, wormholes, nuclear thermal rockets, comet hopping, generation ships and using solar sails.

Riding on Comets: This theory proposes that we could land a probe or a ship on a passing comet, and hitch a free ride to the furthest end of its orbit and back.

Interstellar Ramjets: Interstellar ramjets are basically spacecrafts that produce their own supply of fuel by using the abundant ions present in interstellar space.

Nuclear Fusion Rockets: These are based on the idea that nuclear fusion releases more energy than nuclear fission. Wormholes: Slightly more complex than the other theories, this idea proposes that we create “portals” that connect different parts of the universe.

Nuclear Thermal Rockets: The 1960 usage of nuclear bombs to propel rockets still remains a possibly viable means of interstellar travel. Comet Hopping: Since the space between stars is not empty, why not make use of the interspersed bodies to replenish fuel and even set up colonies?

Generation Ships: Since intergalactic travel currently is supposed to take thousands of years, we could send a colony of human beings, whose descendants would eventually reach the destination. Solar Sails: An idea currently being developed by NASA, solar sails provide a propellant-free means of travel within space.

How to Travel to Other Solar Systems by Hitching a Ride on Comets

Many theories have been proposed to improve the scenario of interstellar travel. The main unifying factors in all these theories are the reduction of time taken to travel, the possibility of human life accompanying the space probe and an economy of fuel. As of now, any country that chooses to send out a probe into space, with the mission of interstellar space travel, stands to lose a lot of money and resources. This is because, such a mission would be extremely expensive due to the infrastructure, technology and fuel involved. In addition, interstellar space travel would call for humongous amounts of fuel, which still will not be able to sustain the spaceship for the entire journey. In addition, any space probe that leaves Earth now would take more than a thousand years before it even reaches Proxima Centauri, the closest star. As a result, the information returned from such a mission would be a long time coming, and the present generation would not benefit from such a mission.

One novel theory that has been proposed since a long time is hitchhiking a ride through space on a comet. Comets travel on a fixed orbit and return every few years. They make long trips into space, outside the solar system, yet they do not fall out of orbit, unless another strong force exerts a gravitational pull on them. This was the reason for the death of the comet Shoemaker-Levy 9 in 1992. It was pulled out of orbit and collided with Jupiter, because of the gas giant’s gravitational power.

Halley’s comet, however, is still in orbit and due to approach Earth in 2061. With an orbital period of 75 years, this comet is believed to travel almost up till Pluto. Other comets, which have longer orbital periods of thousands of years, may travel to various other parts of the universe.

If we release a space ship into space so that it lands on a comet that is passing close to Earth, the ship can then literally hitch a ride into space atop the comet. In other words, it would not need to use any additional fuel to travel to the further expanses of the universe. Another favourable factor with comet travel is the availability of frozen water. If any astronauts are on board the space ship, they can harvest the ice on the comet to produce drinking water and air.

Spaceships aboard a comet can either go as far as the furthest point in the comet’s orbit, or they can hop off at any point along the way. This theory, naturally has its problems. The major problem is that no human would be able to survive for the entire trip aboard the comet. Secondly, they would still have to carry aboard food to survive the journey, and it is quite unfeasible to lug around food for a thousand years. However, all modern innovations require a start somewhere in theory, and this theory is as valid as any of the rest. If space scientists can find a solution or any other alternatives to the problems associated with this theory, they could actually consider using comets as a means of travel into outer space!

Using an Interstellar Ramjet for Intergalactic Space Travel

Intergalactic space travel has remained a dream so far. Even as we have received various images from our telescopes of our neighbouring galaxies, we are still not able to reach them physically.

The nearest galaxy to the Milky Way galaxy, the Andromeda galaxy, is even visible to the naked eye on a clear night. However, we have still not been able to send a spacecraft to this galaxy. No matter how many technological advances come our way, we are plagued by the same problem – the large amount of fuel required to undertake a mission that takes hundreds of years.

However, in 1960, a physicist by the name of Robert W. Bussard proposed a method of intergalactic travel, which came to be known as the Bussard ramjet. The Bussard ramjet is basically an interstellar ramjet, which, if feasible, will make future intergalactic missions a reality. Since the biggest issue with travelling for long distances in space is the amount of fuel required to undertake these journeys, Bussard proposed that we use a spacecraft that creates its own fuel by using the resources available in space.

The spacecraft would have to be able to pick up ions in space, mostly protons. These ions would then have to be sent through a fusion reactor. Here, a proton-proton reaction would have to take place, where the ions would form helium. In this reaction, four protons would be fused together into a nucleus of helium, which would release two neutrinos and two positrons.

In this reaction, hydrogen is turned into helium so that energy is released. The fusion reaction takes place within the spacecraft itself, and the resulting energy is used to propel the spacecraft further along on its journey. In other words, the spacecraft will make use of the ions that are available in abundance in interstellar space in order to create its own fuel, so that it can move along and make more fuel as and when it requires.

However, there are various problems that result in this solution being quite impossible. For starters, it would be difficult for the spacecraft to scoop up sufficient amount of ions, especially if a particular area in space is deficient in ions. Secondly, the action of “scooping” up these ions would create a drag in the motion of the spacecraft, which would have to be compensated by the energy produced.

Finally, it would be difficult to force the protons to fuse together within the rocket itself, so as to set a chain fusion reaction that would release energy. Thus, there are many limitations associated with this solution for travel in intergalactic space.

All the same, if these limitations can be overcome, the self-propelling spacecraft would open up many doors to the universe and allow us to explore pockets of the universe as far as we wish to go, as long as there is a sufficient supply of free protons in the area and as long as the equipment survives the many hazards of space.

Interstellar Space Travel by Nuclear Fusion Rockets

With the wide expanse of the universe beckoning us to explore it, space travel and interstellar travel, or travel from one star to another, has caught our interest in recent years. Even as the Voyager space probes exit our solar systems, we are exploring newer avenues for space travel. All space missions are plagued by the same issues – the amount of time it takes to voyage between the gaping distances of space, the lack of oxygen and other resources to sustain life on longer missions, and the amount of fuel that they call for.

So far, rocket fuel used by scientists to propel spacecrafts has resulted in space missions taking nearly a year or two even up to Mars. The maximum energy that we have been able to harness has been through nuclear fission, or the breaking up of nuclei of atoms. For example, a large amount of energy was released in the Hiroshima and Nagasaki bomb blasts, which used nuclear fusion as the source of energy.

Stars in the universe are long-term producers of energy. This energy is produced as a result of nuclear fusion. Nuclear fusion reactions occur when there is a combination of nuclei of more than one atom. The energy released as a result is far more than the energy released in nuclear fission reactions. However, it is also more difficult to create the conditions for a nuclear fusion reaction, and it is more hazardous to contain the energy produced as a result.

Scientists are, however, looking into using nuclear fusion rockets for future space travel. Theoretically, the advantages of using nuclear fusion to propel space rockets are many. For one, it is a far more efficient source of energy, thus, improving performance of these rockets in space.

This method of propelling rockets would also greatly reduce the amount of time it takes to traverse the distances in space. For example, a Mars mission that currently takes two years to complete, could possibly be achieved within a month.

This reduced travel time would also mean that humans could go on longer sojourns into space, without worrying about their resources running out. The current technology does not allow humans to go much further than the Moon and Mars. However, with nuclear fusion rockets, they can possibly go as far as Saturn or Uranus and be back, without facing too many problems.

In addition, the material required for the nuclear fusing reactions is very less as compared to the rocket fuel in use currently. Even a sand grain of this material can easily provide the same amount of energy as the amount of rocket fuel that spacecrafts use at the moment. However, this theory is currently still under development. It is a problem that requires minds working in both engineering and physics. All the same, it is highly possible that within the next 50 years, we will have more efficient nuclear fusion rockets setting off into space to explore the unknown realms of space.

How to Travel to Other Solar Systems by Using Wormholes

Interstellar space travel has fascinated mankind ever since the existence of a bigger universe beyond our Earth has been proved. With surreal photographs of the lonely planets that lie uninhabited in our solar system, and the possible existence of life in the vast expanse, our curiosity has been piqued endlessly. Theories abound about possible ways to travel into space. The nearest star, after our sun, is Proxima Centauri. However, as of now, with the technology available to us, not only is travel to Proxima Centauri rather impossible, but it would also take more than a millennium for us to reach the star.

There are various theories that are in testing as of now, for intergalactic space travel. Another new method that is being considered theoretically involves the use of wormholes. Wormholes are warps in spacetime that bend the rules of time and speed. It is a distortion in the fabric of spacetime. It is not currently known how we can create a wormhole, using the resources and knowledge that are available to us. However, we do know that we would need to use an enormous amount of energy or matter to create a wormhole manually. This amount of energy is very difficult to get hold of, but if we can somehow lay our hands on it, we could create a man-made wormhole in the universe!

By creating a wormhole, we can possibly create a shortcut or a tunnel between two different locations in the spacetime fabric. In other words, we would have a portal between two far flung locations, such that we could easily cross over from one corner of the universe into another. A major problem associated with the creation of a wormhole is that we have not understood the concept of wormholes very well yet. We have limited knowledge on this topic, and we do not know what exactly would happen if we were to enter a wormhole, much less create one. To add to this, we do not know all the possible consequences of creating a wormhole.

There are theories about time travel that might occur by entering through a wormhole, which would lead to the problem of eliminating our own birth, should we travel to the past and unknowingly change a crucial event. At the same time, theories also abound that anything or anyone who enters a wormhole is bound to be shred into pieces because of the amount of energy contained in such a small, condensed space. Without knowing the exact ramifications of creating a wormhole, we cannot possibly play with fire.

However, should we succeed in creating a portal or a shortcut between two regions by using a wormhole, we would be much better connected to other areas of the universe. We would be able to move from one spot in the universe to another spot, reducing the time taken for space travel considerably, while also connecting various places in the universe conveniently. This would be the most convenient way of travel between locations in the universe, as it would be very comfortable in terms of time and distance.

Using Nuclear Thermal Rockets for Interstellar Space Travel

With the innovations in the field of physics and technology exceeding the pace at which a normal human being can keep up with advancements, one would think that by now, we would have devised a cost-effective and economic way to travel into space, and reach at least the nearest star Proxima Centauri.

However, unfortunately, our advancements have not yet reached this level of ingenuity, as we still struggle to send spacecrafts into the universe, using rocket fuel. However, conventional rocket fuel can only be used for a certain extent, before it runs out or its efficiency starts to diminish. Even within our own solar system, scientists were faced with the problem of speed. If the spacecraft was to accelerate, the amount of fuel used up also increased, as the fuel itself also had to be carried along. All the same, in the 1960s, there was a shimmer of hope in the field of space travel.

Project Orion was a project which undertook space travel with the help of nuclear bombs. Nuclear bombs, which had been considered a destructive force until then, and even now, were put to a constructive use and employed to propel spacecrafts in space. These rockets were called nuclear thermal rockets, and they were supposed to use nuclear bombs to give them the required velocity in space.

NASA developed more than 20 of these special rockets. The program was called NERVA, or Nuclear Energy for Rocket Vehicle Applications. What was once considered a weapon of mass destruction, was now being considered for the development of the human race as a whole. It was indeed, a very fitting use for this weapon that had spread terror among various countries during the two World Wars.

NASA was able to complete 28 test firings of these new rockets for the NERVA program. The premise was quite simple. The spacecraft would drop out approximately five bombs every second to release the required energy to propel the craft forward. The base of the spacecraft consisted of a large shock plate, equipped with suitable shock absorbers. The test firings and various experiments proved that this innovation could be quite viable to send a manned crew all the way to Mars. It was also probably possible to send smaller crafts and probes to visit distant stars, or at least the closest star.

However, the nuclear test ban treaty was signed in the 1960s and effectively brought this solution to a premature demise. Perhaps, if the testing could have been continued, and if the solution was regulated by appropriate bodies, we could be travelling to the stars today using a spacecraft that would be propelled by nuclear bombs.

All the same, similar alternatives, which would release similar amounts of energy, can be considered to send probes and crafts into space. Who knows, if we find the alternative we are looking for, intergalactic travel may not be as far into the future as it seems to be now!

Hopping on Comets to Reach Further Distances in Intergalactic Travel

The call of the vast unknown outside of the Earth has piqued our interest for centuries. The Ancient civilisations believed that the Gods lived beyond the boundaries of the sky. With the slow progress that followed regarding objects in outer space, we have learnt that we are not alone in the universe. We are merely a tiny speck in the large expanse of the universe which seems to be ever-expanding.

With these discoveries came an increase in our appetite for more knowledge. We now want to know more, and we want to see more. It is no longer enough that we should make speculations on what exists in the far reaches of the universe. We want solid proof and we want to know if alien civilisations exist in the universe. However, none of these discoveries will be possible without leaving our Earth. We need to go into the vast expanse of the universe and find out more for ourselves.

With this increase in curiosity came also an increase in theories and speculations about how we can journey into outer space. One of the problems associated with space travel is the need for fuel to propel the spacecraft beyond the Earth. A spacecraft can only carry so much fuel before it runs out of it. Another problem is that humans cannot survive as long as most interstellar journeys are expected to take. However, there is a neat, albeit somewhat disconcerting solution proposed to overcome both these limitations.

As we are well aware now, the space between stars and planets is not empty. There are millions of stray bodies flying around in space, such as the Oort Cloud at the outer boundary of our solar system. Conventionally, space travel is thought of as a continuous journey through the universe, with no stopping point between the origin and the destination.

However, there is no reason why we cannot make stops along the way on various isolated bodies. This will allow us to harvest the resources on that body to replenish the fuel supply of the spacecraft, much like a layover in flights.

Secondly, we can establish colonies all along the way to our destination, which would allow humans to flourish on other celestial bodies. Perhaps, a generation or two would be required to finally reach the destination, but we would ultimately reach our destination, and the information thus found could be relayed back to Earth.

The disconcerting fact is that a few generations would be completely brought up in space, with hardly any contact with their parent civilisation. In addition, the generation that finally reaches the destination will not be the same that returns to the Earth, and perhaps the return journey would never be made. A new colony might be established elsewhere in the universe, consisting of humans who have never had proper contact with their species on Earth. All the same, we cannot be sure of finding celestial bodies that will have enough resources to provide fuel or to sustain life as we know it.

Nevertheless, it is a possible way to travel through the vast void of space to reach other stars and galaxies, as well as to establish other possible colonies of humans in the universe.

How to Travel to Other Solar Systems Using Generation Ships

The increase in the knowledge that we have gathered regarding the universe and outer space has only increased the thirst in us to know more about our neighbours and everything that lies in the vast beyond.

With every new discovery that we are making in the realm of space, we are pushed to explore further than what we are already aware of. We have built telescopes that can open a window into a world that is far beyond what we can see with our naked eyes. However, we are yet to step into another galaxy physically or with the help of probes.

Intergalactic space travel is yet a dream for us due to the various difficulties that such a mission poses. For one, with our current technology, it would take us a long while before we ever reached the nearest star, Proxima Centauri. We are talking in terms of thousands of years. No human could expect to achieve that kind of life expectancy, making this mission impossible for any one team of humans. Instead, what we will need is multiple generations of human beings who will undertake the mission over a long period of time. In other words, this kind of mission can be made possible through the use of a generation ship.

A generation ship refers to a spaceship that is sent on a long distance voyage, with a self-sustaining biosphere enclosed within it. The humans within the ship will spend their time interacting and reproducing so as to ensure the next generation of humans aboard the ship. As the first generation dies, the second will take over and continue in a similar manner, reproducing and passing their time aboard the ship. This process will continue for multiple generations, ensuring that the next generation is always assured to continue the journey. Meanwhile, the generation ship will keep voyaging through space, intent on reaching its destination.

When the ship finally reaches the destination, the voyagers onboard will be descendants of the original voyagers. They will then relay back information to earth through the ship, and they might even set up a colony at their destination.

As with all other theories, there are problems associated with the generation ship as well. We cannot eliminate the human factor involved in these kind of missions. The generations in between will undoubtedly be plagued by a sense of being used, as they will not get to see the results of the mission. They will feel used for the purpose of merely reproducing the consecutive generation. In addition, with isolated groups, the possibility of a mutiny is always there. In other words, the entire mission may be sabotaged or compromised due to these unpredictable factors aboard the generation ship.

However, this proposition has taken the fancy of many futuristic sci-fi authors, and it has featured in quite a few books. It can be considered as a possible means of travel into space, if we can find some way to overcome the limitations presented by it.

Interstellar Space Travel Using Solar Sails

Solar sails and solar sailships are nothing new to the world of science fiction. In fact, the first known person to have considered solar sails is Johannes Kepler, who wrote to Galileo that if we use sails that take advantage of the space weather, we could probably discover many new areas in our universe. This was way back in 1610. Arthur C. Clarke even penned a short story in 1963, in which is featured a yacht race in the universe using solar sails. Thus, the concept of solar sails is not new, but has been around for a while.

The existence of solar winds was discovered when astronomers realized that comet tails would always point in the opposite direction from the sun when they were in orbit near it. This is when they realized that the energy released by the sun was not only in terms of heat and light, but also in terms of winds. Then, why cannot we use solar winds and harness this energy to power our spacecrafts?

A solar sail does exactly that. It is made of a suitably strong material, while also being light, so that it does not need any fuel or propellant to move in space. It is governed by the direction of the solar wind, and its huge surface area allows it to collect solar energy to help in propulsion along certain directions.

In fact, this is no longer merely a theory! NASA has been working on a solar sail which will be sent into orbit in 2014. This mission is dubbed as the Sunjammer, referring to the title of the Arthur C. Clarke short story. The solar sail produced for this mission is made out of a very strong material known as Kapton. This allows it to receive thermal insulation, protection from tiny meteoroids as well as a shield from all the solar radiation it is bound to come in contact with.

The photons that emanate from the sun will propel this solar sail. Despite its surface area of 13,000 sq feet, the sail is collapsible and requires a very small area for storage. The weight of the sail is just more than 30 kilograms. As of now, the solar sail will only be involved in data collection to improve space weather prediction and warning systems and perhaps, in the removal of space mission debris around the Earth.

The best feature of a solar sail is that it costs almost nothing to be propelled. It is free of propellants, since it is powered by solar energy. Thus, if we can establish travel aboard, or with the help of a solar sail, it would be a very inexpensive way to discover our universe! If the Sunjammer mission is a success, it could spell a new era in the world of space travel, as we can definitely start exploring the possibilities of travel using a solar sail. Even if there are problems involved in the mission, it is a very feasible method of interstellar travel, and it is the closest we have come to a propellant-free means of travelling.

The Future of Interstellar Space Travel

With so many theories abounding regarding intergalactic and interstellar travel, we can be quite sure that we will make some significant progress in the next hundred years. As our knowledge of the vast unknown expanse keeps increasing, we can keep making modifications to our theories and propose alternatives that are more feasible than the current ideas.

Voyager 1 and Voyager 2 took more than 36 years to reach the outer boundary of our solar system. By using solar sails, it is expected that we could cover the same distance within a mere 15 or 18 years. This cuts the current time taken into half, making it extremely feasible to send more probes into the interstellar medium beyond our solar system.

As we travel more in space, we also learn more about the conditions in the universe. We can make use of various natural phenomena to propel ourselves further and faster, radically changing the unattainable status of intergalactic and interstellar space travel. For example, space sails make use of the solar wind that occurs naturally in the universe. Voyager 1 and 2 used the gravitational force of the larger planets such as Jupiter and Saturn to propel themselves further into space. This is called a “gravity assist” and requires a certain alignment of the planets in the solar system.

The more information we gather and the more we use our imagination, we can come up with many more theories that will probably provide the inspiration for future space travel. After all, it was Jules Verne’s imagination that allowed him to picture a ship that travelled under the sea, and this ship was subsequently invented and called the “submarine”. With more advancements in the area of physics and more people taking an interest in the field of astrophysics, we have a brighter chance of coming up with novel ways to traverse the vast expanse of the universe. Who knows, maybe a generation ship might really be invented and fired off into space in the future! Perhaps, at the end of this century, we would have reached Proxima Centauri, or at least been in its vicinity.

The newest avenue for space travel has opened up in the form of space tourism. Certain people have enough purchasing power to undertake a luxury trip to the Moon and back. If this pans out, we might have an additional inlet for funds, which might allow even more freedom in our innovations. If we can succeed in taking a man to the Moon, we can definitely succeed in interstellar space travel some day!

All it takes is a little patience, innovation and a little help from the universe, quite literally! The future of space travel is quite bright, as there are many areas that need to be developed in this field. With ever-improving technology, we can someday conceive of a manned mission to Mars, and maybe all the way to Pluto, and perhaps a long while later, of a manned mission beyond the contained world of our solar system.


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