World Ships: The Long Journey To The Stars
posted by Kelvin F. Long on August 29, 2011
A World Ship is a very large vehicle many tens of kilometres in length and having a mass of millions of tons, moving at a fraction of a per cent of the speed of light and taking hundreds of years to millennia to complete its journey. It is a self-contained, self-sufficient ship carrying a crew that may number hundreds to thousands and may even contain an ocean, all directed towards an interstellar colonisation strategy.
Progress toward the creation of World Ships relies on much of the same science, engineering and technology as required for interstellar probes. Advances in our understanding of interstellar engineering in general, through projects such as Daedalus, Icarus and others, all feed into the body of knowledge that might support the eventual building of World Ships. Some have questioned why Project Icarus is using mainly fusion-based propulsion, so it’s important to clarify here the purpose of the project. At heart it is a designer capability exercise, which aims to develop the next generation of capable designers who can then do the relevant calculations for a wide suite of problems relating to interstellar research. The design team anticipates that no less than around 80-90% of the thrust generation during the acceleration phase will be via fusion reactions, allowing for 10-20% enhancements from alternative propulsion schemes. So the design team has a watching brief to keep an eye on alternative propulsion systems as well as to learn how to do the engineering and physics calculations. This also extends outside the propulsion area. In fact all elements of spacecraft technology are potentially relevant to Project Icarus, whether small, large, slow, fast or even superluminal. For example, back in 2007 one of us (Long) organized a one-day conference on the ‘warp drive’ at the British Interplanetary Society (BIS) headquarters in London. This was possibly the first ever conference dedicated solely to this concept. This led to several interesting papers, magazine articles and a documentary on interstellar travel. It was at this meeting that Long and the other Project Icarus co-founder Richard Obousy first met each other. Similarly, Pat Galea attended the International Solar Sailing Symposium in New York City in 2010, meeting up with luminaries such as Greg Matloff who is now a consultant to the project. These meetings are important for both Project Icarus, and for interstellar studies in general, as they allow like minded individuals to interact and share ideas. With this in mind, we recently organised a symposium on the World Ship concept in London. The symposium took place on the 17th August 2011, at the BIS headquarters. Just as the warp drive conference was the first of its kind, this may be a first for World Ships. Around 30 people attended the meeting and this included one person who had travelled all the way from Chicago, and another from Toronto, just to attend the meeting. Several other members of the Project Icarus team attended, including Pat Galea (co-chair) and Andreas Hein. Two of the original Project Daedalus Study Group, Alan Bond and Gerry Webb, were also in attendance. Alan Bond had worked on World Ship concepts with Anthony Martin and others in 1984, leading to a famous ‘Red Cover’ version of the Journal of the British Interplanetary Society (JBIS) exploring the history, engineering, finance and sociology relating to World Ships. The purpose of the recent meeting was to review progress in the intervening years, discuss new ideas, and provide for reflection on the classical definition of a World Ship, as provided by Bond and Martin in their 1984 papers. The meeting consisted of several talks (which are listed below and discussed in more detail in a parallel Centauri Dreams article to be posted shortly. The Enzmann Starship: History & Engineering Appraisal, K.F.Long, A.Crowl, R.Obousy Communications Between Worldships, Pat Galea World Ships: The Solar-Photon Sail Option, Greg Matloff World Ships – Architectures & Feasibility Revisited, Andreas Hein Why World Ships?, Gerry Webb A Development Roadmap for the World Ships, Stephen Ashworth On the Financing of World Ships & Other Gigascale Space Projects, Frederik Ceyssens, Maarten Driesen, Kristof Wouters Some important points are worth noting from the symposium discussions. The extensive searching for information on the Enzmann starship by Long, Crowl & Obousy emphasises the importance of aspiring designers to get their concepts down on paper and preferably published in either a peer-reviewed journal or a popular magazine. It is difficult for like-minded physicists and engineers to progress an idea, if the idea itself is not well defined. One of the issues that arose with the Enzmann Starship concept is that members thought the allocated mass available was too small, ranging from 150 tonnes/person at journey start to 15 tonnes/person at journeys end. Galea’s concept for using the Sun’s gravitational focus to communicate with a distance space probe (based on an idea from Claudio Maccone) seemed tantalisingly plausible, although the laser targeting and accuracy requirements, along with the challenging thrust requirements of a relay craft at the focus, make it a difficult system to build in practice. Solar sail concepts for World Ships were presented in a paper by Matloff. The use of solar-photon sails were regarded by some members as having large technical issues, particularly in relation to controlling the continuing oscillations that the sail would experience during the journey. The presentation by Hein laid out a comprehensive way to define the requirements for a World Ship, and to think about the key stepping stones required before such ships could be assembled and launched. The creator of Project Daedalus and one of the authors of the 1984 World Ship papers, Alan Bond, gave Hein’s presentation a big thumbs up. Webb’s very considerable exposition of the link between science fiction ideas, culture, and the construction and launch of a world ship was one of the most entertaining presentations of the day. His presentation led to discussions on the sociology of a world ship, be it democratic or dictatorial in form. Webb envisioned many World Ships being launched to the stars, each containing its own culture (or religion), with the result that only those that possessed the ‘right’ characteristics succeeding; a consequence of Darwinian evolution in action. Ashworth’s very detailed talk on the justifications for world ship construction was one of the highlight lectures of the day. He delivered the lecture in a Presidential address style, demonstrating his excellent skills in articulating his independent thinking. The final talk of the day was given by Ceyssens who argued that we should prepare for World Ship developments today (or other MegaProjects) by building up a seed fund of investments. His specific proposal for his own Millennium Fund Foundation. However, Alan Bond commented with a note of caution that in his opinion it is likely that money, in the way that we understand it, will not be used as a means of controlling resource allocation in the future. All of the presentations were well thought through and provided a variety of insights into an important problem for the future: how to colonise the stars. When studying these huge concepts, one rapidly realises the importance of interstellar (unmanned) precursor missions. These are essential stepping stones to be attained before one could even think about the construction of a World Ship. Concepts like those developed for Project Daedalus and Project Icarus become even more important. We must know a great deal about our destination and the technology to be used before we personally embark on such a trip. Another important requirement is cheap, quick and reusable access to earth orbit for the construction of large vehicles. It is quite clear that conventional launcher technology will not provide for this capability, especially at the expense of around $50,000/kg. The largest mass robotic interplanetary spacecraft put into space to date was the Cassini-Huygens probe at around 2.5 tonnes. If we wanted to put something more massive into orbit perhaps we could use a larger rocket, but there is a practical limit to how big it could be, placing a restriction on the payload mass. So perhaps you could launch two separate rockets, or five or even ten, and then assemble the vehicle in orbit. But how many launches are required before it becomes prohibitively expensive? We need another way. Single Stage to Orbit (SSTO) concepts, such as the Skylon Spaceplane being developed by the UK based Reaction Engines, have the potential to reduce launch costs to as low as $3,000/kg. This is probably the only way that large space based infrastructure capability is going to be built, realistically. The aerospace industry and governments need to realise that if humanity (not just robots) are to have any future in space, then we must be bold and start to invest in this technology now. As Stephen Ashworth argued at the symposium, World Ships will likely be a logical end point to the slow diffusion of our species through the solar system and beyond. World Ships may be many centuries away, but development of routine access to space would be a catalyst to achieving greater things in space, and help us all to direct our energies to more positive ambitions, and realise our purpose in this magnificent cosmos that we inhabit. It’s humbling to think that even if our civilization could manage to launch something as big and ambitious as the Project Daedalus probe, this would be only the starting point for human colonisation of the galaxy. We are a young species and the journey ahead is long, but with optimism, hope and the motivation to keep trying, we will eventually becoming a star-faring civilisation. Some Pictures From The Meeting: