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ISEC

2014 Conference Mini-Workshop

Concepts & Issues in Space Elevator Research

A summary report from the Research mini-workshop at the International Space Elevator Conference in Seattle

John Knapman

Workshop leader

December 2014

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Introduction

A wide-ranging discussion of research-related topics was conducted as a mini-workshop at the 2014 Space Elevator Conference in Seattle.

Workshop Goals

The goal of the mini-workshop was to stimulate thoughts and inputs from the conference attendees on space elevator research projects. Some detailed objectives were:

• Gain an awareness of the ISEC Research Committee's goals and process
• Review the list of topics that the Committee has produced
• Identify potential contributors with relevant skills and interests
• Where possible, add some level of detail, particularly on those topics where little work has so far been done
• Where possible, propose who could carry out the work and where

Discussion notes

From the teams at separate tables, discussions developed observations, ideas, proposals, and preliminary conclusions in several areas. What follows are notes representing highlights from those discussions.

Tether Materials

Key concerns:

• Manufacturing limits, cost requirements
  • Designing around industrial production
• Possibly use biological production methods-bacteria producing CNTs or precursor carbon compounds?
  • Following the work of Harvard professor George Church in synthetic biology
• Assemble a list of researchers with facilities that can produce "vendor amounts" of CNT, preferably non-CVD produced
• Single wall, double wall - different markets
• Rotating assembly? Two carbon chains at a time?
• We need a growth model
• Hybrids between graphene and CNT for strength?
• What are the possible benefits from putting dielectric material inside CNT lattice?
• Drawing out tubes uniformly
  • Can this be aided by electrodynamics?
• How does the height of the array affect tangling? Do CNTs tangle as they grow, or is there some optimal length to which to draw out filaments?
• Crowd sourcing? With bulk material, we let every high school in Oregon learn to use/make CNTs.

Global Cooperation

How do we work internationally? There are multiple potential contributing organizations and roles:

• ISEC
  • CLIMB journal 18 months
  • Architecture and roadmaps
• Japan Space Elevator Association (JSEA)
  • Similar functions
• IAA
  • Academy Study on space elevators
• United Nations
  • Possible committee opportunity here too
  • Related treaty experience (Antarctic treaty, Outer Space treaty)
• Intelsat
  • Originally an intergovernmental consortium with a similar goal of providing space-based services to its governmental participants
• Obayashi Corporation
  • Has expressed an intent to deploy a space elevator by 2050

Should space elevator research and development be funded commercially, through governments, or both?

• Decision would determine applicable legal and social frameworks

Philosophical foundations for international cooperation

• What is the objective of building?
• Why are we doing it?

Tether-related research

• How do we manage connect/ disconnect events for climber/tenant
• Reserve space on tether - always have it
• Maybe have wider tether
• Center of gravity and center of mass management
• Debris, flux sensors and meteorological shielding
• Unplanned stopping
• Lasers - avoid satellites with sensors
  • Safety issues
  • Torsion/ twisting
  • Coefficient of friction

Dynamics Analysis & Electrodynamics Modelling

Electrodynamic Modelling should be integrated with the mechanical dynamics analysis, even though there will be many more unknown factors requiring different resolution methodologies. Related issues include:

• Radiation
  • Radiation protection and remediation for passengers and cargo (live animals and other biological material, food & water, medicine, delicate equipment)
  • Evaluations of shielding solutions
  • Radiation testing would be simulated initially; lab tests would follow when material or mock-ups become available
• Sun pressure on solar sails could cause deflection
• Solar wind an issue outside the magnetopause
• Compare forces on integrated structure - simulated and experimental
• Solar storm could move the FOP
• Conductivity of tether could be affected by electromagnetism

Forces and factors that need to be included in the model:

• Gravity (from multiple bodies, at least sun & moon)
• Rotation of earth
• Solar and lunar tides
• EM fields-need to develop a comprehensive 3D model of the radiation environment up to 17 earth radii (100,000 km)
• Earth anchor location: what happens as the Marine Node is moved?
• Tether properties: flexibility, torsional behaviour of ribbon, capacitance, conductivity (electrical & thermal), thermal expansion/contraction, albedo, moment of inertia, ...
  • Could model initially as Zylon (or similar), then change to CNT as properties become known
  • Need results from historical tether tests

Also, what sort of computer systems will be needed to run the integrated system model? These requirements can be estimated based on benchmark testing of existing tether models.

Conclusions and Highlights

It would be highly desirable to come up with an integrated tool that can combine a model of the tether's mechanical dynamics with its electrodynamics. These two will influence each other because electric currents induced in the tether will interact with the Earth's magnetic field. The model of the radiation environment needs to feed through to the tether's electrodynamics but does not need to be so closely coupled.

Ideas on tether materials included using bacteria or synthetic biology. A summary of active research work and contacts would be useful. Crowd sourcing may make progress; for example getting school-children to experiment with CNTs.

International cooperation could include writing science fiction with positive outcomes. The International Academy of Astronautics (IAA) has set up an Academy Study on space elevators. Bilateral agreements between countries would be a good way to make progress; a global treaty can come later. We need to learn from the Obayashi Corporation in Japan and develop a story to attract other companies.