On the Strength of the Carbon Nanotube-Based Space Elevator Cable: From Nano- to Mega-Mechanics

TL;DR

This paper assesses the strength of carbon nanotube-based space elevator cables using new models, revealing significant strength reduction due to defects, which challenges the feasibility of current design assumptions.

Contribution

The paper introduces new quantized models for nano- to mega-mechanics to estimate the realistic strength of defective space elevator cables.

Findings

Predicted cable strength is reduced by at least 70% due to defects.

Experimental and simulation data support the strength reduction.

Current cable designs may be insufficient to prevent failure.

Abstract

In this paper different deterministic and statistical models, based on new quantized theories proposed by the author, are presented to estimate the strength of a real, thus defective, space elevator cable. The cable, of ~100 megameters in length, is composed by carbon nanotubes, ~100 nanometers long: thus, its design involves from the nano- to the mega-mechanics. The predicted strengths are extensively compared with the experiments and the atomistic simulations on carbon nanotubes available in the literature. All these approaches unequivocally suggest that the megacable strength will be reduced by a factor at least of ~70% with respect to the theoretical nanotube strength, today (erroneously) assumed in the cable design. The reason is the unavoidable presence of defects in a so huge cable. Preliminary in silicon tensile experiments confirm the same finding. The deduced strength reduction is sufficient to pose in doubt the effective realization of the space elevator, that if built as today designed will surely break (according to the s opinion). The mechanics of the cable is also revised and possibly damage sources discussed.