LiftPort’s mission is to provide cheap, safe and reliable access to space. We believe that the space elevator will enable such access. A few space elevator feasibility studies and preliminary designs have already been performed by different groups. These studies have generally suggested a space elevator consisting of a wide, thin ribbon anchored to an equatorial, ocean-based station on one end and connected on the other end to a counterweight roughly 100,000km up in space.
The ribbon is climbed by lifter vehicles which are powered from the ground by lasers. The technical roadmap presented here is based on this design. Any system architecture changes made in the next few years should not significantly change the total timeframe or budget. This roadmap is an outline of the major tests and demonstrations that must be performed (whether by LiftPort or others) for technical, legal, and political reasons before the space elevator can be built. While we have considered many non-technical milestones, that side of the space elevator has not been developed enough to be able to outline the required steps with much confidence.
The space elevator project will be one of the greatest engineering projects in the history of mankind. The largest obstacle to building it is the high-strength, low-weight material needed to make an economically feasible space elevator. Although more is always better in the case of material strength, we are basing the road map on a “minimum” specific strength that is roughly 15 times better than the best current materials. Carbon nanotubes (CNTs) have shown promise in lab experiments to meet this requirement, but to scale up from microscopic lab samples to industrial material production is a development process which will take years. The rate of development of the carbon nanotube material greatly affects the timeframe in which the space elevator can be built. While some skeptics believe that the requisite material will not be developed in the next century, other optimists think a breakthrough will happen within the next few years. Our view is somewhere in the middle; we speculate that the necessary material will be available around 2020, making commercial operation of the first space elevator possible by the year 2031 if there is adequate funding and no major developmental setbacks. This timeline will obviously slip if the material advancement takes longer. Unfortunately, the completion date will not happen much earlier even if the requisite material were available in bulk quantities right now.
Research and development of the numerous other required technologies should begin as soon as possible, though, for two reasons. First, there is an enormous amount of work to be done in areas other than the ribbon material. Second, the spin-offs from these research fields will be of great value whether or not the space elevator is ever built.
Global awareness of the space elevator concept and its perceived feasibility is still low. In order to clarify some of the steps that need to be taken before this revolutionary method of space access can be built, we are publishing the attached road map. There is a one page schematic overview, as well as a three-page Gantt chart for those interested in more details. Aspects of this road map are subject to debate, and we expect input from various quarters will enable us to revise the road map and update the time estimates.
The perceived feasibility of the space elevator can be improved if a diverse, coordinated, and global group of interested parties pursues the large amount of preparatory research required.
Like other companies working in emerging fields, LiftPort has pursued partnerships with researchers in academia and industry to advance the state of knowledge. But the space elevator is larger than any single company. We at LiftPort want to promote an open approach to space elevator development, especially because it is an exciting project for students and researchers to get involved in. To encourage people around the world to learn more and to contribute to the growing body of public knowledge, we have created a freely-available online resource containing space elevator-related research problems. It is available at http://questions.liftport.com.
The site and its content are still being developed, but we encourage everyone with an interest in the project to get involved. LiftPort aims to use this site as a way to coordinate the global research efforts surrounding the space elevator.
Although LiftPort is involved in the production of carbon nanotubes, we will likely rely on the global development of high strength CNT materials. While we assume the material will be available around the year 2020, earlier availability will not particularly speed up development of the space elevator. The various tests and demonstrations are dependent on three milestones of increasing material strength occurring between now and the year 2020.
As one of the largest infrastructure projects in history, the space elevator will require a huge inter-disciplinary research effort. To kick-start the research, LiftPort is hosting a public online resource containing space elevator related research problems, now available at http://questions.liftport.com. We encourage you to browse through the questions, to tackle any that are of interest, and to contribute new questions. We hope that this resource will inspire researchers to expand their own related projects to help address questions of importance to space elevator development. The questions database should provide the focus for near-term academic research. Topics will include high-resolution laser focus & tracking, ribbon dynamics, evaluating & addressing physical threats, preliminary designs of major components, as well as addressing legal & business issues. The research will encompass not only “paper” analysis, but laboratory experiments as well.
Tethered high-altitude balloons allow us to investigate many aspects of space elevator operations without the expense of space-based tests. In fact, LiftPort has already begun work in this area with a 1.6km altitude test and a 2 month endurance test of balloon systems. Next, a series of three progressively higher balloon-lofted ribbon tests will be used to evaluate multiple issues.
The first test, to an altitude of 3km, will demonstrate basic ribbon dynamics and control as well as a prototype lifter vehicle. A second test to 10km will examine operation of the lifter vehicle in varying atmospheric conditions, ribbon behavior and spooling control, as well as weather effects on the ribbon. The third test, aiming to reach an altitude of 30km or more, will continue the investigations from the 10km test and also test power beaming to an improved lifter vehicle prototype.
The longest tether ever deployed in space was roughly 20km long. Given the history of problems in tether experiments, it would be imprudent and impractical (at best) to go immediately to a 100,000km system. In addition, much can be learned by smaller scale tether design experiments before the final carbon nanotube-based ribbon material is available.
The plan to address all the necessary orbital research minimizes the number of launches because launching space-based tests is currently expensive (a fact which the space elevator is intended to remedy). First, a retired satellite will be used to test tracking and focus of laser power beaming from the ground. At about the same time, the first of a series of three increasingly longer tether deployment missions will go significantly beyond current experience, deploying a 200km-long tether. Next will come a 2,500km-long tether. Both of the tether tests will demonstrate ribbon deployment & control, and debris-dodging ability for a pre-touchdown ribbon. The third tether mission will be roughly 30,000km long. The bottom of this tether will be a few hundred kilometers above the altitude at which GPS satellites orbit, enabling safe demonstration of the ability to dodge satellites. A lifter vehicle traversing the ribbon will be powered remotely by laser, demonstrating an integrated system operating in orbit. Last, an orbital material exposure facility will validate the combined effects of the orbital environment on the final ribbon material.
After the necessary research is performed, a detailed engineering design of the components of the space elevator can begin. Designing, prototyping, testing and fabricating the anchor station, lifter vehicle, power beaming system, and counterweight will entail large teams working for many years.
Once all designs are finished and all components have been produced, the space elevator will be assembled, launched and deployed. Once the initial “seed” ribbon is in place, the system will bootstrap itself by lifting new ribbon into orbit and adding it to the initial ribbon. This process will take at least 16 months to scale the ribbon up to a commercially useful capacity. When it is completed, the space elevator will enable high-capacity, low-cost cargo transportation to Earth orbit and beyond.
A schematic overview of the road map is on the next page. This diagram gives a rough idea as to the physical regimes in which various system demonstrations will take place, as well as the time required.
For more details, including dependencies between the elements, please see the three-page Gantt chart that follows the schematic. Each activity was set to occur as early as possible, limited only by dependencies on the completion of other activities.
The LiftPort space elevator road map was developed by Tom Nugent, Jasper Bouwmeester, Michael Laine, and Mannix Shinn. We are very thankful for the valuable input and feedback provided by Jordin Kare, Robert Hoyt, and Robert Carlson.