Almost fifty years ago, humanity saw its first successful manned mission to the moon, an event made possible by a massive growth in space research, known now as the “Space Race.” Just last week, on November 12th, the European Space Agency became the first to land a probe on a comet, when their Rosetta mission successfully landed on comet 67P/Churyumov–Gerasimenko. However, the propulsion technology used to complete this historic achievement remains largely the same: chemical combustion engines. Chemical combustion is great as long as we just need to make (relatively) short flights around our solar system, but, due to some weird features of Newtonian physics, the exhaust velocity of a rocket is a key limit on the distance the rocket can travel, and chemical combustion rockets just don’t cut it for long distance space travel. The first question you might ask is, “Why should anyone care about travelling outside of our solar system?” The simplest justification is simply survival. As we approach Earth’s carrying capacity for human population, with some estimates as low as 10 billion people, and continue to rapidly exhaust the natural resources at hand, we need to find another place to expand to if we want to survive. But spacefaring also appeals to humanity’s desire for exploration and discovery. Not only could we discover more about our place in the galaxy, but spacefaring research allows us to gain a greater mastery over the nature of our universe. Unfortunately, the difference in the distance from the Earth to the moon and the Earth to the next closest star is massive. The Alpha Centauri system, the closest system to our solar system is about 4 light years away. That is over 250,000 times larger than the distance from the earth to the sun. Even farther, the closest habitable planet is almost 12 light years away. In contrast, the farthest we’ve ever travelled from Earth, the Voyager probe, is only 17.9 light-hours away. Discounting the fact that this journey would take thousands upon thousands of years with our current technology, the amount of fuel needed would be absurd. Funnily enough, there is actually a theory out there that any interstellar mission that would take longer than 50 years shouldn’t be undertaken, because we could develop a faster propulsion method and launch a faster mission in the same amount of time. Luckily, there are currently many proposed methods of better space travel. One very achievable advancement would be the fission rocket. The fission rocket operates on a similar premise to chemical combustion rockets, but instead of burning fuel, the rocket uses nuclear fission to superheat hydrogen and then expels it to produce thrust. There are various groups pursuing this technology in an effort to travel to Mars, such as Icarus Interstellar Inc. and General Propulsion Sciences. An even more advanced form of rocket, the antimatter rocket, would provide huge amounts of thrust, but only if we could find a way to store the antimatter and prevent it’s huge amount of gamma emissions from killing the crew and destroying the ship. Even fission or antimatter rockets, however, would still not be prime candidates for interstellar travel because of their need to carry fuel along with them. Non-rocket propulsion is theoretically possible, but not with our current technological propulsion systems. One of the most feasible methods would be a solar sail. Essentially, a spacecraft would be attached to a massive magnetically charged sail propelled by solar radiation. Because the sail would be powered by solar radiation, the ship could accelerate constantly, reaching velocities that would be impossible with a traditional rocket. A more speculative (and theoretically impossible) thruster is the microwave thruster. Essentially, the thruster would bounce microwaves around in a box, a concept that in traditional Newtonian mechanics shouldn’t produce thrust, but whose feasibility has been confirmed by three separate laboratories, including NASA. Finally, the most outlandish, but definitely fastest, method of propulsion would be a warp drive that could travel faster than the speed of light. According to Einsteinian Relativity, faster-than-light travel is impossible through space time. Because of this, a warp drive would not propel a spacecraft through spacetime, but instead move space around the craft, allowing it to escape the confines of spacetime. In addition to new propulsion methods, many other concerns must be addressed. Travel at the speeds necessary to reach other stars would put the craft at risk of being damaged by dust and other microscopic rocks in space. In addition, navigation could only occur with a hyper-accurate atomic clock, and communication over huge distances requires more advanced systems than what we have today. And, if the voyage were to take any amount of time, even solutions for mundane necessities, like a method for recycling the air, water, and food on a ship would need to be developed. Interstellar travel may seem daunting, but this article was not intended as an insurmountable list of hindrances to humanity’s ability to escape our solar system. Instead, it may be seen as a to-do list for those who turn their gaze upwards. One hundred years ago, a mission to the moon seemed impossible, but with proper motivation and allocation of resources, humanity accomplished the impossible. Interstellar travel may seem impossible, but we must always first recognize what needs to be done before we can do it. Already, private and public groups alike are tackling the many problems of spaceflight. And although it may not seem like we’ve made much progress since the first mission to the moon, India’s recent unmanned mission to Mars cost less than the production of the film, “Gravity.” If interstellar travel is possible in theory - and it definitely is - then it’s possible in practice if we put our minds and efforts to it. This article was written by Cameron Ballard. Send an email to [email protected] to get in touch. Photo Credit: Wikimedia Commons