Space Elevator Downer

Scientists and science fiction fans alike have big plans for carbon nanotubes; it has been hoped that a cable made of carbon nanotubes would be strong enough to serve as a space elevator. However, recent calculations by Nicola Pugno of the Polytechnic of Turin, Italy, suggest that carbon nanotube cables will not work.


(Looking down a carbon nanotube)

American engineers worked on the problem in the mid-1960's. What type of material would be required to build a space elevator? According to their calculations, the cable would need to be twice as strong as that of any existing material including graphite, quartz, and diamond.

Science fiction writer Arthur C. Clarke recognized the materials problem; his ingenuity was equal to the task of creating just such a material. In his excellent 1978 novel The Fountains of Paradise, he thought up a special form of carbon, something called a "continuous pseudo-one dimensional diamond crystal," to serve as the cable material. To the delight of sf fans and aerospace engineers, Japanese researcher Sumio Iijima (at NEC) discovered carbon nanotubes, which are cylindrical carbon fibers exhibiting strength 100 times greater than that of steel at one sixth the weight, and high strain to failure.

In something of a "downer" for space elevator fans, Pugno has calculated that inevitable defects will greatly reduce the strength of any manufactured nanotubes. Laboratory tests have demonstrated that flawless individual nanotubes can withstand about 100 gigapascals of tension; however, if a nanotube is missing just one carbon atom, it can reduce its strength by as much as thirty percent. Bulk materials made of many connected nanotubes are even weaker, averaging less than 1 gigapascal in strength.

In order to function, a space elevator ribbon would need to withstand at least 62 gigapascals of tension. It therefore appears that the defects described above would eliminate carbon nanotubes as a usable material for a space elevator cable. Pugno will publish his paper in the July edition of Journal of Physics: Condensed Matter. Nanotube enthusiasts counter that ribbons made of close-packed long nanotubes would demonstrate cooperative friction forces that could make up for weaknesses in individual nanotubes.

Read more about Arthur C. Clarke's one-dimensional diamond crystal; in Carbon Nanotube Ribbon for Space Elevator a method of creating meter-long nanotube ribbons is described. A robotic lifter that would traverse a space elevator ribbon has also been tested. Read more about the current controversy at Nature.

Scroll down for more stories in the same category. (Story submitted 5/26/2006)

Follow this kind of news @Technovelgy.

| Email | RSS | Blog It | Stumble | del.icio.us | Digg | Reddit |

Would you like to contribute a story tip? It's easy:
Get the URL of the story, and the related sf author, and add it here.

Comment/Join discussion ( 13 )

Related News Stories - (" Space Tech ")

A Floating Cosmodrome
'...a single perfectly level platform, which rose so high above the water that it was not splashed by the waves.' - Otfrid von Hanstein, 1930.

Space-Based Solar Power Roundup
Who first thought about this concept?

'Aerogel' Sheets For Martian Gardens
'Sealed to the ground along all the sides, Honey, he growled...' - Raymond Z. Gallun, 1951.

Michelin Self-Sealing Tires On Ford's Explorer
'...a seal of compressed plastifoam to save the air.' - Jack Williamson, 1941.

 

Google
  Web TechNovelgy.com   

Technovelgy (that's tech-novel-gee!) is devoted to the creative science inventions and ideas of sf authors. Look for the Invention Category that interests you, the Glossary, the Invention Timeline, or see what's New.

 

 

 

 

 

Current News

Zephyr Solar-Electric Stratospheric Drone
'The planes flew continuously, twenty-four hours a day...'

Robot Hummingbird Hovers Biomimetically
'With a buzz... it started out on its journey.'

Harvest Water From Air With Sunlight
'The atmosphere yielded its moisture with reluctance.'

Capitalist Big Brother Co-Opts Regular Big Brother
'It was even conceivable that they watched everybody all the time.'

A Floating Cosmodrome
'...a single perfectly level platform, which rose so high above the water that it was not splashed by the waves.'

First Artificial Memory Formed In Animals
'Is an extra-factual memory that convincing?' Quail asked.

Maintain Your Megastructure
Megastructures have repair robots, which have repair robots, ad infinitum.

Venezuelans Teaching Your Self-Driving Car
‘She wouldn't stop until Antar had told her everything he knew...’

Robothread Robotic Worms Crawling Through Your Brain
Perfect for clot-busting in the human brain. No Raquel Welch and no lasers, though.

Vantablack BMW X6 Is Douglas Adams Approved
'It's so... black!' said Ford Prefect.

Humanoid Robot's Muscles Biomimic Ours
'It is remarkable that the long leverages of their machines are in most cases actuated by a sort of sham musculature...'

Animatronic Robotic Baby Exposed
'The birth of Machine, my robot child...'

Beijing HaiDiLao Robotic Hotpot Restaurant Now Flavored By Artificial Intelligence
'Kantos Kan led me to one of these gorgeous eating places where we were served entirely by mechanical apparatus.'

Plants of the Future - What Should They Be Like
'He almost choked in his astonishment. Mashed potatoes and brown gravy!'

China Deploys Robot Traffic Police
'The robot came up smooth and fast as a rocket...'

Better Than Dune Chromoplastic? This Guy Might Have Done It
'But when Old Father Sun departs, the chromoplastic reverts to transparency in the dark.'

More SF in the News Stories

More Beyond Technovelgy science news stories

Home | Glossary | Invention Timeline | Category | New | Contact Us | FAQ | Advertise |
Technovelgy.com - where science meets fiction™

Copyright© Technovelgy LLC; all rights reserved.