On the Development of Affordable Space Travel William Earley 26th March 2013 Abstract Space travel is a dream to many, but there has been little change to the prohibitive expenses involved. By examining the history and current state of space travel it is possible to identify the reasons why we strive for space and why progress has slowed. Looking at research into cheaper, more affordable launch vehicles, as well as using mathematical analysis and computer simulations to evaluate the costs involved, the transition from a mainly governmental to private space industry can be considered, and the prospects of new space startups is evaluated. Whilst it is too soon to tell for sure, private space companies are having a lot of preliminary successes, and it would appear that the already impressive cost reductions will continue as supply and demand catch up. It is important to recognise the limits of rocket-based launches though, and that even cheaper space travel needs more radical solutions, however there is currently little interest in these techniques. Nevertheless, the future looks hopeful for affordable space travel and it may not be long before extraterrestrial colonies and space tourism become commonplace. 1 Contents 1 The Current State of Spaceflight3 1.1 History..............................................3 2 Motivations 5 2.1 Opinions..............................................8 3 Preliminary Analysis 10 4 Technology 13 4.1 Current.............................................. 15 4.2 In Development.......................................... 18 4.3 Unmanned Spaceflight...................................... 22 4.4 Theoretical............................................ 24 5 Conclusion 27 A Interstellar Travel 29 B Derivations 32 B.1 Rocket Equation......................................... 32 B.2 Adjustments........................................... 33 B.3 Solid-State Travel Equation................................... 34 B.4 Rocket fuel efficiencies...................................... 35 C Evaluation 36 C.1 Sources.............................................. 36 C.1.1 Academic Journals.................................... 36 C.1.2 Other Publications.................................... 37 C.1.3 Books........................................... 37 C.1.4 Online Technical References............................... 37 C.1.5 Interviews......................................... 38 C.1.6 Internet.......................................... 38 List of Figures 38 List of Tables 39 References 39 2 1 The Current State of Spaceflight During a recent trip to the airport, I came across an advert from Virgin promising the opportunity to `travel in space from just $30'. Unfortunately, the advert was referring to upgrading to more leg room, however with the rise in new space industry startups such as Virgin Galactic and SpaceX, and the ubiquity of space tourism and exploration in popular culture, I was inspired to consider the cost of getting into space, and how far away many people's visions of space seem to be. It's been over forty years since the last mission to the moon, and the space shuttle has just recently been retired. Can these new startups take over from where NASA left off, and can they make any substantial reductions to costs? Even though space exploration is in its infancy, prices are still exorbitantly high and have shown little improvement, with space tourists paying upwards of $20 million, and space shuttle launches costing $1:5 billion on average. This raises questions about its viability as a commercial industry, and whether or not abundant and affordable space travel will ever be a reality. While for many, the reasons for going into space are obvious, it is important to identify the motivations for our potential future exploration of space if we are ever going to achieve a significant subsidy and reduction in costs, and it is also necessary to seriously consider alternatives to primarily rocket based launches, such as space elevators. Few would doubt that space travel could be cheaper, but by just how much? There is a substantial energy cost in moving even small masses from the surface of the Earth into orbit, and then even more so for attaining a suitably fast trajectory for interplanetary missions. There are also expensive technology and materials considerations for protecting astronauts and equipment on the journey from radiation and debris; However, by looking at aerodynamics, thinking laterally, and investigating alternative fuels, it may be possible to theorise about a space-based economy in the future, where going into space is as easy and as common as boarding an aeroplane. 1.1 History The history of spaceflight should be seen as a culmination of thousands of years of dreams, myths, experimentation and scientific discovery. It begins with the ancient Babylonian legend of Etana and the ancient Greek myth of Icarus. Whilst these stories don't directly address the topic of spaceflight, and have more important over-arching interpretations about origins and ambition, the fact that flight into the heavens is featured at all shows a distinct example of the human spirit and our desire to explore. Nevertheless, the first important breakthrough didn't occur until 3 the first century, when the Chinese developed a crude form of gunpowder, and real advancements were not seen until the last millenium. The first documented use of rockets occurred in 1232, when the Chinese repelled a group of Mongolian invaders with `arrows of flying fire’. This battle inspired the Mongolians to develop rockets of their own, and later spread the technology to the West, where the gunpowder recipe was improved to increase the range, and new methods of rocket launching were developed to improve accuracy (Benson 2010). The next major breakthrough came in the sixteenth century, with the invention of multistage rockets by a German fireworks maker, an idea common to most modern rockets. Finally, after centuries of use in warfare and fireworks displays, a Chinese official by the name of Wan-Hu linked the use of rockets and flight, and attempted to realise the dream by strapping forty-seven rockets to his chair. Whilst his attempt was unsuccessful, it marked the first recorded use of rocketry in transportation, and was a significant milestone. With the establishment of Newton's Laws of Motion in the seventeenth century (Newton 1687), the basic underlying science of rocketry was discovered. Meanwhile, rockets were becoming more advanced, as Germans and Russians began experimenting with rockets exceeding forty-five kilograms of mass, and the British Rocket Corps exhibiting a range of almost two kilometres. This was accompanied by a rise in the popular culture surrounding rocketry and an acknowledgement of its potential for space travel, with Jules Verne's book `From the Earth to the Moon', and H. G. Well's `The War of the Worlds'. It wasn't until the late nineteenth and early twentieth centuries, however, with Konstantin Tsiolkovky's publication of his theories on rocket propulsion (Tsiolkovsky 1903), that the ability to escape the confines of Earth was proved, and the dream of spaceflight finally validated (Tsiolkovsky 1911). Tsiolkovsky's influence went much further still though, as he also proposed designs for numerous critical aspects of modern spaceflight, including airlocks, multistage boosters, and even space stations. For his pioneering works, Tsiolkovsky is often considered the father of astronautics and he laid the foundations for the groundbreaking technology developed over the twentieth century. He enabled the space race, including the launch of the first men into space. The final prerequisite innovation came with the first successful launch of a liquid-fuel rocket in 1926 by Robert Goddard. Following this, the German's produced the V-2 liquid-fuel rocket, and then, in a 1944 test flight, the first rocket reached the 100 km altitude mark, and then surpassed it by another 89 km (Reuter 2000), signifying the success of thousands of years of dreams, experimentation and scientific discovery. What followed was an eighteen year space race in which the USA and Russia competed extensively to beat each other to successive space-based 4 milestones. 1957 - Sputnik-1 becomes the first artificial satellite, heralding the start of a world-changing communications and monitoring revolution. 1957 - Sputnik-2 takes the first animal into space, proving the dream is possible. 1961 - Yuri Gagarin becomes the first man into space, inspiring hundreds more to follow. 1969 - Apollo 11 takes man to the moon, and humanity walks on another world. 1976 - Viking 1 becomes the first spacecraft to successfully land on Mars, another planet. Over the next few years, the first spacewalks, spacecraft rendezvous, and dockings were achieved. Both sides also succeeded in launching space laboratories. Then in 1998, the first permanently inhabited structure, the International Space Station, started construction, and become a symbol for international cooperation. Unfortunately, despite all these achievements, most have simply been in the name of competi- tion and national pride, with little attention to cost effectiveness or prolonging and advancing our exploration of space. With the end of the space race, it has been over forty years since a man landed on the moon, and repeated budget cuts and program cancellations have delayed numerous NASA missions and even led to the retiring of the Space Shuttle (Day 2011), leaving the USA without a means to transport astronauts between the ISS and the Earth, with Russia left responsible