International Space Elevator Consortium
Summary of Research Projects

The primary research priority for the space elevator is to find a material that is strong, long and light enough.  The second priority is to work on ways of reducing the strength requirement while still carrying a useful amount of payload.

Other important areas are:

• Climber Engineering, in particular the interface between the climber and the tether. Requirements include:

  • High climber traction with minimal degradation of the tether

  • High climber reliability and durability

• Progressing the simulation work on tether dynamics (Dennis Wright, Dan Gleeson, Arun Misra, Stephen Cohen), including:

  • Stability

  • Libration

  • Electrodynamics

  • Magnetosphere models

  • Effects of radiation

• Finding the optimal method of moving the tether to avoid space debris:

  • Swinging the base and propagating a wave

  • Moving the earth port at sea

  • Reel in/reel out at Earth Port, GEO, and/or Apex Anchor

• Understanding the effects on the tether of impacts with space debris, which will differ according to the material used:

  • What is the effect of rupture on a tether made of single crystal graphene, which is now our preferred material?

  • What is the effect on a carbon nanotube weave, which is an alternative material?

  • The same questions apply to other candidate materials, such as boron nitride.

• Alternative designs with two or three tethers for the sake of greater resilience to items of debris smaller than 10cm and other potential damage:

  • The Obayashi Corporation proposes dual tethers, each capable of supporting the weight of the climbers.

  • Another proposal is to have three tethers so that, even in the worst case of an impact that passes obliquely through two tethers, the third is still capable of supporting the climbers’ weight.

Strong Materials

Single crystal graphene is a very promising material. Essentially, the crystals are extremely strong molecules of carbon that are one third of a nanometer thick : we need them a meter wide and kilometers long. We are engaged with a team led by Adrian Nixon and based at the Graphene Engineering Innovation Centre (GEIC) in Manchester, UK. They are developing a method of manufacture that uses liquid metal so that the graphene can be formed on the metal’s surface (as shown) and then pulled away without damage.

Reducing the Strength Requirement

Ben Shelef calculated the minimum acceptable strength for a tether based on the amount of time needed for maintenance and repair while still carrying payload : this is important, because it enables the space elevator to be built sooner. He defined a new unit of specific strength, the Yuri [named after Yuri Artsutanov, a Russian pioneer of the space elevator], which is tensile strength over mass density.

John Knapman proposed an approach – the Multi-stage Space Elevator – that builds on Shelef’s work and adapts Keith Lofstrom’s idea of the Launch Loop. The plan is to support the lower parts of the tether from the earth’s surface using the momentum of objects traveling very fast in a vacuum. Magnetic levitation with electronic control prevents collisions. A team in several countries is engaged in building a small-scale working prototype. Gravity is strongest near the earth (Figure 1), so the tether can be made of a much weaker material using this method of support.