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 ")

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

Mining Of Golden Asteroid Foretold In 1898 Science Fiction
'This must be a golden planet—this little asteroid.' - Garrett P. Serviss, 1898.

Miners! NASA Wants To License RASSOR Excavator
'The borers had been dismantled and packed away.' - Ray Cummings, 1930.

Starshade Will Help Space Telescope To Search For Exoplanets
'When it found planetary systems in its field, automatically shifted upon them a higher powered telespectroscope ...' - Edmond Hamilton, 1936.

 

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

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

Mushroom Eats Plastic, Saves Planet
Fungus Amongus, SaveUs!

Juggalo Face Paint Disrupts Facial Recognition
'... designed to foil facial recognition systems.'

Mojipic Smart Voice Vehicle Emojis
KITT, what's your response?

Unusual Twist On Woman Dates Robot
'My hearing, vision and awareness went along with that excellent imitation of a young Adonis...'

BrainNet Triple Telepathic Gaming Threat
'In the gloomy half-darkness the three idiots sat babbling.'

AVAS Noisemakers Required For EVs By EU
'...a sound tape to supply the noise of a soi-disant "[internal combustion]" engine...'

Pun Generation Via Neural Nets
'You said you wanted him to be able to distinguish between laugh-power in different gags...'

Blood Battery Robotic Fish
'With one fluid motion, it surged forward, plunged, and was gone.'

Lightyear One Solar-Powered Electric Car (Design By Heinlein)
'It drew its power from six square yards of sunpower screens on its low curved roof.'

'Agression Detectors' Don't Work When Spying On Students
'The professional agitators had also learned how to modulate their voices below the danger level...'

Mining Of Golden Asteroid Foretold In 1898 Science Fiction
'This must be a golden planet—this little asteroid.'

Miners! NASA Wants To License RASSOR Excavator
'The borers had been dismantled and packed away.'

Bee+ Robobee Now With Four Wings
'It was a tiny thing, scarcely more than an inch and a half in length...'

CNSILK Robotic Spider Builder
'We could certainly spin a web right through the Solar System, if we can think of a good use for one.'

Starshade Will Help Space Telescope To Search For Exoplanets
'When it found planetary systems in its field, automatically shifted upon them a higher powered telespectroscope ...'

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.