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Super strong carbon nanotube fibers for unprecedented industrial applications in sight – results of Luxembourg Space Elevator Climber and Tether Workshop
On November 10-11, 2007 EuroSpaceward A.s.b.l. held the 1st European Workshop on Space Elevator Climber and Tether Design . This has been the first conference of its kind to discuss the construction of space elevator climbers and super strong space tethers related to the part of NASA’s Centennial Challenge Program that is managed under the denomination “Space Elevator Games” by the US Spaceward Foundation, a liaison partner of EuroSpaceward. The workshop was held in Luxembourg to encourage participation by European engineers and scientists and was gratefully supported by the National Research Fund of Luxembourg.
The conference attracted approximately 50 attendees from all over Europe, the U.S., Canada and Japan. The talks covered not only specifics of what has been successful at the recent contest of NASA’s Beam Power and Tether Challenge in Salt Lake City in October 2007. But also plans and requirements for NASA’s 2008 contest as well as discussions of the rapid development of carbon nanotubes (CNT) which are widely expected to be the material of the future for super strong aerospace structures and other industrial applications, being theoretically more than 100 times stronger than steel at approximately one fifth the weight of steel.
The most exciting components of the workshop centered on two areas: the development of carbon nanotube threads with a target tensile strength of 20 GPa, four times stronger than any existing strong material, and the announcement for next year's Space Elevator Contest, possibly held at Arizona’s Flagstaff Meteorite crater.
Dr. Brad Edwards, President of EuroSpaceward, opened the technical part of the workshop with an update on the current development efforts of the Space Elevator System and the progress made.
Dr. Marcelo Motta from the Department of Material Science and Metallurgy at Cambridge University presented their most recent work. Over the last three years they have steadily improved their CNT production techniques and are now able to make fibers with strengths as high as 9 N/tex which corresponds to approximately 9 GPa at the density (1g/cm3) of the fibers produced in their Lab. (It is 2 times stronger than Zylon, the worlds toughest commercially available fiber). This value corresponds to the peak of a distribution of strengths obtained along the fibre length, ranging from 1.5 to 9 N/tex. (More details can be found on the references of Dr. Motta's presentation in EuroSpaceward's download section). This is a strength improvement of roughly 100 over the last four years for the group at Cambridge. Dr. Motta noted the challenges to scaling up the process but this achievement is monumental. It is a large step toward what is needed for the space elevator and demonstrates the basic truth that strong CNT threads can be made! The exciting results of this work may soon start to positively impact industries like construction or aeronautics. 
In addition to the Cambridge work Prof. Vesselin Shanov from the University of Cincinnati’s Nanoworld Research Lab presented their accomplishments in growing CNT arrays up to 18 mm long (see image of CNT wafer cake). This was noted by Dr. Motta as an accomplishment that paves the way for even better threads. These two presentations covered the best leading work in CNTs today.
Dr. Patrick Choquet from the local public research center Gabriel Lippmann gave an overview about the possibilities to enhance functionalisation of CNT fibers by plasma treatment and Dr. Pierre Rochus, Deputy Head of R&D at the Liege Space Center introduced their instrumentation to eventually test CNT threads for space application.
World record: array of 18 mm long Carbon Nanotubes grown by the team of Prof. Shanov at UC.
In discussions of the Space Elevator Games for 2008 Ben Shelef, Head of the US Spaceward Foundation, announced that NASA and Spaceward are seriously considering a climb height of 1 km - ten times what it was this year, for next year’s NASA Beam Power Challenge. It was also evident that there is growing interest in the games at NASA itself and in private industry because of the performance of the teams and particularly the first laser-powered ascent, seen at the recent contest in Salt Lake City. Mr. Shelef stated an interest in Spaceward providing lasers for teams to use in 2008. This would greatly reduce the expenses on the teams and allow more to compete. Other changes for next year include the ribbon being replaced by a cable, the crane being replaced by a balloon and the prize money going up to $900k for both the tether and climber competitions. An addition to this is that in the last couple days Spaceward has released that it is considering raising the prize purse to $2M for each competition if higher performance is accomplished. With the state of the competitors these requirements are within reach.
The 10kW diode laser head manufactured by DILAS Inc. that powered the winning climber of USST at the NASA challenge in Salt Lake City.
Dr. Georg Treusch, Dilas Inc. Tuscon, highlighted the capabilities of diode lasers for NASA’s Beam Power Challenge. He estimated the costs for a diode laser system capable to power a climber on a 1km vertical track at about USD 100k. On a more generic level Benoit Michel, Université Catholique de Louvain Belgium, proposed a hybrid winding solution to the Space Elevator power problem.
Further to the discussions on CNT development and 2008 Space Elevator Games the workshop provided valuable information from the organizers and the 4 competition teams present (USST Canada, ETC Japan, Tesla Munich and Recens Barcelona) on what needs to be done to be a successful contestant at NASA’s Beam Power and Tether Challenge. The basic design issues of the climbers and tethers and the tactics of the teams were discussed. There were obvious traits (technical skill) but much time was spent discussing the less obvious and more critical components of how the winning teams tended to focus on their own climber and what they needed to make it happen whereas the less successful teams tended to worry about the other teams, had less organization and more personal conflict issues, according to Dr. Bryan Laubscher.
The highly successful workshop was concluded with an outlook by Markus Klettner and John Winter on the potential economic and environmental need of the Space Elevator as a means for large scale expansion of mankind into outer space.

For more information on the workshop please see Workshop Abstracts, or enter the EuroSpaceward member page for a full coverage of the workshop presentation. (Luxembourg 19 Nov. 2007)
 

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