SpaceElevatorEnvironment

The Environment

The elevator stretches from the Earth to high orbit - passing through Earth weather, the ionosphere, radiation belts and out beyond the Earth's magnetosphere. In each of these environments there are concerns and hazards for the space elevator and a complete understanding is required to be able to produce a viable design.

Hazard	Impact	Details / Solutions
Lightning	Severed ribbon	Solution: Anchor location in lightning-free zone
Wind	dynamic destruction of the ribbon	Solution: Anchor location where limited wind, ribbon design
Radiation 1	ribbon degradation	Solution: Select CNTs and other materials for ribbon that are radiation resistant
Radiation 2	hazard to electronics and cargo	Solution: May be able to ascend at a higher speed and use shielding (passive and active) to get radiation to acceptable levels
Debris	ribbon destruction	Solution: Ribbon design with a width larger than a meter insures only a small part of the ribbon will be damaged by any impact. The ribbon design also isolates damage along the length of the ribbon. Active avoidance limits impacts larger than 1 cm.
Meteors	ribbon destruction	Same as for debris though lower flux and active avoidance can not be used.
Earth's magnetic field	Current generation in ribbon	Ribbon is geosynchronous so only flucuations in the magnet field will create any current and this is small
Interplanetary magnet field	Current generation	The ribbon travels quickly through the interplanetary magnetic field but the field is too weak to generate and substantial current.
Solar wind/particles	ribbon degradation	same as radiation above
Gravitational influence	ribbon oscillation	The Moon and sun will both exert a gravitational pull on the ribbon at a roughly 24 hour period. The natural frequency of the ribbon is about 7.2 hours and there will be little coupling
Thermal cycling	ribbon wear and oscillation	Each day the lower end of the ribbon will go in and out of the Earth's shadow. This will change the temperature and length of the ribbon
Atomic oxygen	ribbon destruction	Solution: Coating the affected section of the ribbon with an oxygen resistant material

Additional Work Needed

Item	Notes	Completed and Ongoing Efforts
Full characterization of environmental effects	Start from "The Space Elevator" book and studies done by others	The Space Elevator by Edwards, Westling
Detailed model of ribbon magnetic field interactions
Detailed model of damage extent and flux due to meteors	Include the expected increase in orbital debrisover the next couple decades.	File:The Leonids and the SE.odt by Edwards
Thermal modeling of the ribbon during transition between sun and shadow

Major Work Items Required

• Experimental tests of ribbon in atomic oxygen
• Radiation protection for humans in transit
• Detailed modeling of ribbon degradation lifetime

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