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 |
you like to contribute a story tip?
Get the URL of the story, and the related sf author, and add
Comment/Join discussion ( 13 )
Related News Stories -
Yes, But Do Astrobees Have Lasers For Lightsaber Training?
'... Ancient weapons are no match for a good blaster at your side, kid.' - George Lucas, 1977.
Japan Uses Explosives On Asteroid
'...a tiny, rocket-powered projectile, drove towards the mysterious bulk. It hit, exploding into a cloud of incandescent vapour.' - EC Tubb, 1958.
Johns Hopkins Says Asteroid Deflection Will Be Difficult
'This obelisk is one huge deflector mechanism...' - Gene Roddenberry, 1968.
Hayabusa 2 To Begin Asteroid Mining
'We must dig down, and then doubtless we shall find the metal.' - Garrett P. Serviss, 1898.
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.
Asimov and Musk - Boring Company Tunnel vs. Street Race
'There was almost no sound, just a steady velvety whirr as the taxi sped along.'
Project Dylan - Amazon's Voice-Activated Wearable That Recognizes Human Emotions
Life imitates anime art.
Tesla Diagnoses Itself, Sends Part Request
'Tentacles emerged from the side of the machine and felt puzzledly at the damaged area.'
Lilium Electric Air Taxi Prototype
'The air-taxi found its way past and around other ground-cars...'
Swedes Premiere T-Pod Driverless Electric Truck
'the trucks gulped packages and scurried like beetles...'
HEL TVD Laser System To Be Built By Dynetics Lockheed Martin
'Forthwith flashes of actual flame, a bright glare leaping from one to another, sprang from the scattered group of men.'
Alcarelle Synthetic Alcohol Like Star Trek Synthehol
Datagrid Model Generation Perfect For Eternal Cities Of Science Fiction
'... there was enough flexibility to allow for wide variation.
Kazahk Ironist Protester Arrested For Blank Sign Protest
'...a man carried a white rectangular sign, blank on both sides.'
Bitcoin Surges Again, To $7,000
'... electronic, private cash, unbacked by any government, untraceable, completely anonymous.'
China Develops Taste Testing Robots
'Install taste buds in the end of one tentacle...'
North Sea Stone Age Reconstruction And Philip K Dick
'Your Dip digs back into antiquity. Rome. Greece. Dust and old volumes.'
Tesla Robotaxis Will Automatically Recharge Themselves
'Then it appeared to make up its mind, and trundled over to a wall socket...'
New Lifelike Material Powered By Artificial Metabolism
'... The biological robots were not living creatures.'
Husqvarna Automower 435X AWD
'Gramp Stevens sat in a lawn chair, watching the mower at work...'
Elon Musk Foretells Tesla Sans Steering Wheel
'How about the steering wheel... I don't need one.'
More SF in the News Stories
More Beyond Technovelgy science news stories