International Space Elevator Consortium
September 2015 Newsletter

In this Issue:

Editor’s Note
President’s Corner
Mini-Workshop Report
Research Lab
Historical Files

Editor’s Note

Dear Friend,

Welcome to the September, 2015 edition of the ISEC eNewsletter.

Knowledge gleaned from the recent ISEC Space Elevator Conference is a focus of this issue.  The President's Corner discusses some of the presentations at the conference and the Mini-workshop on Space Elevator Simulation is summarized.

This month's "Research Files" column discusses special problems that must be considered for the portion of the space elevator tether that is in earth's atmosphere while this month's "Historical Files" talks about the upcoming release of the new ISEC publication "Via Ad Astra" and two of the articles in it that target early and later space elevator history.

If you want to help us make a space elevator happen, JOIN ISEC and get involved! A space elevator would truly revolutionize life on earth and open up the solar system and beyond to all of us.

Please don’t forget to LIKE US on Facebook, FOLLOW US on Twitter, and enjoy the photos and videos that we’ve posted on Flickr and YouTube, all under our Social Identity of ISECdotORG.

Thank you! 
ISEC

President's Corner

This year's ISEC Space Elevator Conference [Aug 21-23, Seattle Museum of Flight] was especially rewarding for me.  Three major events showed significant progress towards space elevator development:

  • Keynote Speech by Mark Haase entitled, Advances in High Strength Materials. This keynote speaker left us all with "good feelings" towards the future of high strength materials.  Mark laid out the situation and explained that while it may not be immediate, there is hope for the future of getting to 20-25 MYuris in carbon nanotube materials.  In addition, he explained that there was a second material that could also reach those levels in tensile strength, Boron Nitride.

  • A successful International Academy of Astronautics Study Group meeting:  This study group consists of 20+ global experts in space capabilities and is entitled:  "Road to the Space Elevator Era."  The meeting had participants from ISEC, IAA and the Obayashi corporation.  The following agreements were reached:

    • There would be a common development of terminology for the study report based upon both Japanese and American inputs.

    • There seemed to be four phases to the construction of a space elevator: R&D, Launch to GEO, Deployment to IOC, IOC to FOC. This combined the best of the developmental scenarios of both the previous IAA study [2014] and the Obayashi concept [updated 2015].

  • The next year-long study for ISEC was announced during a short brainstorming session.  The title of the study will be:  "Design Considerations for GEO Node and Apex Anchor."  There will be three major segment discussions during the study activities; What does a GEO Node look like?  What does an Apex Anchor accomplish? and, What communications architecture is required to support both?

Keep Climbing my Friends --  Pete Swan
        (pete.swan@isec.org)

Report from the 2015 Space Elevator Conference Mini-workshop on Space Elevator Simulation

A mini-workshop on a software space elevator simulator was held at the ISEC conference in Seattle this past August.   It concentrated on three areas: the physics inputs necessary for the development of a realistic space elevator simulator, the benchmarking of simulator models and ideas and suggestions for developing a state-of-the-art space elevator simulator and its software infrastructure.

A presentation by Dennis Wright discussed the physics inputs already present in existing tether models and those that need to be added.  Ideally, these should include longitudinal and transverse vibrations, torsion and the Poisson ratio. Bending due to the stiffness of the tether does not appear to be important.  It was noted that almost all space elevator calculations depend on guesses for the material parameters of the tether material and an appeal was made for researchers in strong materials to measure these parameters.

One of the best ways to learn about the behavior of space elevators is to compare several simulated versions of it against one another.  A program to do this has begun in ISEC and was discussed in a talk by Peter Robinson and Dennis Wright.  In the beginning stages of the benchmarking exercise, two existing space elevator models were tested by establishing identical starting conditions and comparing the tether motions that each model produced.   Each model was required to simulate a 100,000 km tether anchored at the Earth's surface with large masses at GEO altitude and apex anchor.  Many things were learned about how to refine the benchmarking process for the future, chief among them the need to iterate the process with better definitions of tether profiles and physical constants.  A call was made for other entries into the benchmarking process so that a wider variety of mathematical and physical simulation methods could be tested.

A goal of ISEC is the creation of a state-of-the-art space elevator simulator and the software infrastructure to support it.  To inform this project several brainstorming sessions were held at the conference.  The main areas discussed were: who would be the customers or users of this simulator, what would be the scope of the project, what capabilities should the space elevator models have and what kind of software infrastructure would be needed to support them.

The customer base in the early years would likely be small, constituting a niche market of initial investors and academic researchers.  The simulator could possibly be marketed as an add-on module for such well-known codes as MATLAB and ANSYS. Another potential early market would be computer gaming where space elevators are already in use.  Later users would include tether operators who need to simulate detailed tether motion and use it for real-time feedback to tether actuators.

The simulator project will be a large effort and it was recognized early on that it must start with very basic models and then repeatedly add sophistication.  To define the scope of the project it would be useful to first survey the availability of existing proprietary and open source modeling tools in order to avoid duplication of effort.   The scope of the project can also be defined by its products, which currently include models of a pathfinder 1000 km tether experiment, the full tether deployment scheme, its operational mode and several failure modes.  Management oversight, including a Work Breakdown Schedule (WBS) would be required to ensure that the project stays within scope.

A high quality, professional simulator must include a long list of physical effects.  In addition to treating the necessary vibrations and torsion, the model should include all known external and internal influences on the tether such as motion at the Earth, GEO and apex nodes, gravitational effects of the Sun and Moon, electromagnetic interactions with the magnetosphere, internal and external friction, heating and cooling due to the tether moving in and out of Earth's shadow, solar and atmospheric winds, multiple climbers and thrusters on climbers.  The ability to model various tether deployment scenarios and the deployment of payloads at various points along the tether is essential.  All this will need to be calculated with sufficient speed to allow real-time corrections of tether motion.

The simulator will be operated and supported within a software infrastructure which allows modular, extensible code development and takes advantage of modern computer architectures and distributed computing. Relatively low-cost computing power could be obtained on the Cloud or through the harvesting of un-used capacity as done by SETI@home. The infrastructure should be multi-platform, multi-developer and multi-user, with high quality visualization and user-friendly web interfaces.  It was recommended that developed code should be open source and released in the form of a toolkit or library of modules which would make it easy to use and combine with other applications.

A software simulator will be essential to space elevator development and operation, first as a tool to understanding space elevator behavior, then as an aid to design and finally as a source of the calculations needed for daily tether operations.

The Research Lab

The space-elevator tether is designed to withstand the challenges of radiation, meteors and debris in space, but people often forget about the challenges of dealing with the Earth's turbulent atmosphere. Electric storms and ice can have a significant effect, but the main consideration is the effect of winds. Normally, when a rope, flag or other object is in the wind, we fasten it tight to stop it blowing too far. The space elevator is to be permanent infrastructure, and we have to design it to cope with whatever weather may hit it, which will sometimes be quite extreme. Fastening the tether tight involves putting substantial extra tension in it, which means it has to have the strength to match.

It helps to design the 'atmospheric tether' in a shape that is narrow and thick - say 4 cm wide instead of a meter wide. Within the atmosphere, a climber goes inside a box, which has its own climbing mechanism. The box also protects the climber's photovoltaic arrays. This design of box protection and an atmospheric tether still requires the main tether to be about six times as strong as is necessary for lifting the climbers' weight.

A more radical solution is to replace the atmospheric tether with a structure known as 'high stage one.' This deals with winds and other phenomena without affecting the tether, which is kept above most of the atmosphere. High stage one is a development of the launch loop. It can support a structure at high altitude by means of fast projectiles traveling inside evacuated tubes using magnetic levitation to minimize friction. Scale models and prototypes need to be built to turn the concept into reality.

The Historical Files

The first of many articles from the members of the ISEC History Committee is published in the new ISEC Magazine, Via Ad Astra - the Road to the Stars.  This inaugural issue of our magazine will be published by the end of October and will be available on our website, www.isec.org.  This publication will feature articles of interest for those of you who, like me, find the idea of a space elevator fascinating and who want to learn more about this most magnificent of engineering concepts.  This first issue has two articles from the History Committee: 1) First major article outlining space elevator history and, 2) First in a series of interviews.  

The first is entitled "Early Space Elevator History - Tsiolkovsky, Artsutanov, and Pearson."  This view of our industry giants is quite revealing as step by step progress is made.  The first is a thought experiment, the second is a great layout of the concept while the third shows engineering analyses and projections into the future that have come true.  Each of these players in space elevator history are shown to have grasped an idea and the wonderful advantages afforded to humanity when it comes to fruition.  

The second is the summary of an ISEC oral history interview with Mr. Vern Hall.  One of the questions that is always asked early in our oral history interviews is:  "Please describe how you first heard about the space elevator."  Vern's answer was like so many others:  "I heard of the concept in popular publications like National Geographic, several years ago, and it is a very interesting concept."