Carbon Nano Technology Thread

[redavni]

Speaking of biology, I wouldn't be surprised if the biologists beat the chemists to a scalable nanotube process. DNA contains blueprints for all sorts of complex molecules already. It doesn't seem outlandish to think there might be a way to genetically engineer an organism to metabolize CO2, into specifically shaped carbon chains and a bit of oxygen.

 

[nacnud]

Er yes it is. DNA codes for proteins but deciding on the shape of the protein from the string of DNA alone is very, very hard.<br /><br />It is in a class of problems called PN hard, basically the completely of the problem rises exponentially with the size of it. Designing a protein or combination of proteins to make CNT from normal carbon would be virtually impossible.<br /><br />You could design your protein perfectly but it is very hard to make sure that it will fold up in the way you want it to.<br /><br />It is much easier to make these materials mechanically.<br />

 

[gfpaladin]

What are you doing that you are producing atomic oxygen from O2? Same question regarding EMP. Excessive electrical flow?? Isn't C insulating? Unless of course you are placing atoms INSIDE the CNT....<br /><br />What does ANY of that have to do with space tether use? Thanks in advance for your answers...

 

[nexium]

Good questions. Ionizing radiation (such as from our Sun) sometimes converts O3 and O2 to O1 = atomic oxygen. Atomic oxygen does not last but seconds in the lower atmosphere, but it persists long enough to damage surfaces (including CNT) at high altitude. Atomic oxygen attacks many materials even at low temperatures and tethers get quite hot under some conditions.<br />EMP = electromagnetic pulse is a pluse of radio waves. Typically the term is used for very strong pulses that are distructive. H bomb explosions, earthquakes, volcanoes, asteroid hits, super nova, almost anything extremely violent produces EMP. Lightning and other excessive current flow produce radio pulses, but they typically are not strong enough to be called EMP by most people. Diamond is an insulator, but other forms of C = Carbon is usually an electrical conductor, but not nearly as good as copper. It is more like nichrone wire which is used for electrical heating. CNT is electrically conducting, however the epoxy used to hold the fibers together is insulating. Very high voltage will damage the epoxy insulation and high current and high heat can damage the CNT fibers. Most kinds of atoms inside the CNT do not affect the conductivity, however metallic atoms MIGHT increase the conductivity.<br /> It has to do with tethers as modest amounts of electrical power can be obtained from conductive tethers. Large amounts of current damage/break the tether, in much the same manner as a fuse blows. A conductive tether behaves like a radio antenna which can receive radio pulses, including EMP which is likely to destroy the tether due to excessive current flow. Neil

 

[gfpaladin]

<i> Atomic oxygen does not last but seconds in the lower atmosphere, but it persists long enough to damage surfaces (including CNT) at high altitude</i><br /><br />Studies have indicated that it persists long enough to damage surfaces at high altitudes???<br /><br /><i> H bomb explosions, earthquakes, volcanoes, asteroid hits, super nova, almost anything extremely violent produces EMP</i><br /><br />I understand that; I was questioning your concern of the EMP. What is the probability of one of those events (a) occurring and (b) being close enough for the EMP to affect the proposed CNT tether?? Qualitatively, the answer is 'very small'. BTW, I have never encountered reports of EMP associated with volcanos and earthquakes being <i>observed</i>. Do you have a source you could share?<br /><br /><i>Diamond is an insulator, but other forms of C = Carbon is usually an electrical conductor, but not nearly as good as copper. It is more like nichrone wire which is used for electrical heating. </i><br /><br />True...there is conductive and then there is CONDUCTIVE. I guess I read your statement to mean it is a 'good' conductor. From "Rheological behavior of multiwalled carbon nanotube /<br />polycarbonate composites", authors: Petra Pötschke (a), Timothy D. Fornes (b), and Donald R. Paul (b)<br />(a) Institute of Polymer Research Dresden e.V, Hohe Straße 6, 01069 Dresden, Germany<br />(b) Department of Chemical Engineering and Texas Material Institute, The University of Texas at<br />Austin, Austin, Texas 78712, USA, <br /><b> ...studies have shown CNT have diverse electrical properties, capable of acting as metallic-like<br />conductors or having characteristics of a semiconductor depending upon the distortion or “chirality” of<br />the graphite lattice</b><br /><br />BTW, from the same paper <b> various studies involving singlewalled<br />nanotubes (SWNT) and multiwalled nanotubes (MWNT) have demonstrated that CNT can have<br />moduli and strength levels in the range of 200-1000 GPa and 20</b>

 

[chris_in_space]

Are there already some figures concerning conductivity (or resistivity) of a <font color="red">single</font>carbon nanotube (i.e. not in a composite matrix)? Just wondered who long a single carbon nanotube could be before loss through Joules effect would be to high (let's say until 90% of the power is lost through thermic dissipation).

 

[nexium]

I don't have a link. EMP is likely an over-rated hazard. It can be damagingly strong within millimeters of where rock is being crushed, but typically the mechanical forces are far more dangerous, if you are that close. The volts per meter of antenna decreases as the square of the distance from the source of EMP. I think the current is produced by pizzoelectric effect. Neil

 

[nexium]

My guess is 1000 GPA occurs with zero CNT crystal defects per trillion times a trillion atoms, so one carbon atom becoming a nitrogen atom reduces the GPA considerably if we ever reach a GPA of 1000. It appears we can get our carbon from Pennsylvania coal when (and if) we ever get large samples of CNT near GPA = 1000. Neil

 

[douglas_clark]

nexium,<br /><br />Isn't this interesting?<br /><br />http://www.wired.com/wired/archive/11.04/nanotech.html<br /><br />douglas

 

[chris_in_space]

I was also very excited about the idea of a space elevator until I asked myself what for and is it enough to make this 7 billion $ project profitable. Ans sadly I came to the conclusion that it cann't be profitabe since there is no "market" for a space elevator...<br />

 

[douglas_clark]

Chris-in-Space,<br /><br />You may be right. If I could use what I think is a reasonable analogy, if there are two sides to a river or a strait or whatever, there is initially no traffic between them. When people do start to want something from the other side, they use boats and ferries which you could compare to rockets. Eventually, if and when. the traffic rises, someone builds a bridge or a tunnel, which is essentially what a space elevator is. Bridges and tunnels seem to almost generate traffic from their mere existence. So, it might not happen soon, but it could happen sometime.<br /><br />douglas

 

[chris_in_space]

Don't get me wrong, I think the space elevator is not a so bad idea (still we really have to improve that energy beaming, cause 0.1% efficency is quite ridiculous). But we have to find the use for such an elevator cause in my opinion it is an overdimensionated infrastructure for current or near future uses. I think it's like building a toll highway with 16 lanes between 2 major cities in the 1920ies. Of course it will generate it's own traffic. Of course people in the 1920ies would have appreciated having such a good highway but still the highway operator would have been bankrupt after one year. For me it would be the same with the space elevator before there will be really interesting (and profitable) things than can be done in space. So maybe one day when the entrepreneurs will find out what profitable projects they can launch in space and there will be a big enough demand, the space elevator would be a good idea (if the 0.1% efficiency issue can be solved). But until then... <img src="/images/icons/frown.gif" />

 

[douglas_clark]

Chris_in Space,<br /><br /><font color="yellow">still we really have to improve that energy beaming, cause 0.1% efficency is quite ridiculous</font><br /><br />Could you explain what you mean here please? I'm not getting it. Thanks<br /><br />douglas

 

[jmilsom]

Very good summary of Edwards Space Elevator efforts - thanks for posting.<br /><br />The article says: <i>Within two to three years, Highlift should have a material strong enough for the space elevator ribbon.</i><br />I find this hard to believe. Somebody correct me if I'm wrong, but the record length for a CNT remains about 4cm. His four times steel prototype strip, can't be made from continuous woven strands - it must be some form of melded composite. <br />I admire the guy's vision - and maybe he has heap of aces up his sleeve, but there are too many questions in that article to mention. Funding, materials development, getting that quantity of ribbon in to space... etc<br />I do agree with Doug though, build a road or bridge and development follows. It would change the world if this could be done. <div class="Discussion_UserSignature"> </div>

 

[chris_in_space]

Douglas,<br /><br />Concerning the 0.1% efficiency problem it is related to the aforementioned Edwards space elevator design. Basically building and deploying the nanotube ribbon is just putting up a rope. You still have to provide energy to the climber cabins to they can go up. In the Edwards design of the space elevator the energy is provided to the climbing cabins by energy beaming (through a laser if I remember well). The problem is that the efficiency of this laser energy beaming system is about 0.1% which is even worse than the total efficiency of rockets (even considering they carry 95% of fuel and not payload). So in order for the space elevator to be really competitive it has to find a much more efficient energy beaming system. I have my little idea of a better system but it's not yet mature enough (little hint: how about plugging the climber on the grid on the ground and have a long long long wire up to it...)<br /><br />One has not to forget that a space elevator is basically just a rope that goes up in the skies. The way you provide energy to your system is still the key point. Today rocket engines is the best way and it's not a 0.1% energy effcient system that's going to replace these rockets... (even without considering infrastructure costs which are orders of magnitude higher than fuel costs for both systems)<br />

 

[douglas_clark]

Chris-in-Space,<br /><br />Thanks for the clarification. I did read the article I posted, honest <img src="/images/icons/smile.gif" /> I must have stopped at the comparative costs bit though, which seemed to favour the concept.<br /><br />douglas

 

[chris_in_space]

You're welcome Douglas. <br />The comparative costs and economics are definitly put up so they favor the concept. I read some conference papers on the economics of the elevator (papers by their advocates of course) and even I found that their numbers were flawed...<br /><br />Chris

 

[grooble]

Yeah, you could use the money to build a desalinisation plant. <br /><br />*awaits the barrage of eggs*

 

[tempel1]

Dear friends <br />Go here please:<br />http://saturn.jpl.nasa.gov/news/press-release-details.cfm?newsID=117 <br />” The spacecraft's VELOCITY RELATIVE TO THE SUN is at about 26 kilometers per second (about 59,250 miles per hour). Cassini is now more than 9 million kilometers (almost 6 million miles) from Earth”. <br /><br />Since our probe is launched from the earth, it has already a velocity of 65,000 miles per hour (earth's velocity). <br /><br />Why have NASA engineers steered Cassini on this trajectory? <br /> http://www.space.com/php/multimedia/imagedisplay/img_display.php?pic=h_cassini_trajectory_02.gif&cap=The <br /><br />Instead of increasing Cassini's velocity they have slowed down it at 59,250 miles per hour. <br /><br />NASA engineers think the earth is the center of our solar system and don't consider earth's velocity. <br /><br />In this wrong way Cassini has travelled for 2 200 000 000 miles to meet Saturn. <br /><br />Cassini would have been able to fly along a straight line travelling for less than 1 000 000 000 miles. <br /><br />65,000 miles per hour (earth velocity) + 36,000 miles per hour (spacecraft's velocity) = 101,000 miles per hour <br /><br />1 000 000 000 miles : 365 days : 24 hours : 101,000 miles per hour = 1.13 years <br /><br />If NASA engineers considered the earth's velocity, Cassini could meet Saturn in one year! <br />

 

[serak_the_preparer]

<i>I thought I would bump this one to see if anyone has heard of any new breakthroughs...</i><br /><br />Don't know if this is what you're looking for, but I came across these in my travels:<br /><br />Spongy nanocoating makes for fog-free glass by Andreas von Bubnoff (Nature)<br /><br />30 August 2005<br /><br /><i>Imagine glasses that never fog up or reflect light. US scientists think they have the technology to make this happen, along with fogless, reflection-free ski goggles, windscreens, bathroom mirrors and more. <br /><br />Michael Rubner of the Massachusetts Institute of Technology in Boston and his team have developed a nanoparticle coating that reflects just 0.2% of light hitting its surface....</i><br /><br /><br />Nano-material is harder than diamonds by Will Knight (New Scientist)<br /><br />30 August 2005<br /><br /><i>A material that is harder than diamond has been created in the lab, by packing together tiny "nanorods" of carbon.<br /><br />The new material, known as aggregated carbon nanorods (ACNR), was created by compressing and heating super-strong carbon molecules called buckyballs or carbon-60....<br /><br />The researchers found their ACNR to be 0.3% denser than ordinary diamond and more resistant to pressure than any other known material....</i>

 

[nexium]

Thank you Serak. Both of those are good news for the space elevator. Reduced reflection means more energy reaches the photovoltaic cells.<br />A harder than diamond surface means reduced abrasion of the photocells and the tether.<br />I also missed the 0.1%. Let me guess that it means, worst case. The very first climber is 10,000 miles up the tether. Heavy clouds are blocking all 5 of the lasers that power the climber. The tiny storage battery is dangerously low. 10 kilowatts are needed to keep the climber laying thread at the maximum safe rate and trickle charge the battery, so we run all 5 lasers at maximum power, a total of 10,000 kilowatts, input power. 10 divided by 10,000 = 0.1%, but this will happen rarely, perhaps never again after the 100th thread is in place, as the tether is stronger and can tolerate heavier climbers with much larger batteries, and it is less urgent to lay thread at the maximum safe rate. Also there are now ten climbers on the tether which can share 4 out of 5 of the laser beams. Less than 1% of the energy delivered will be rare. 20,000 kilowatts divided by 200 kilowatts (we have upgraded the lasers) = 1%. 20,000 kilowatts for one hour costs $2000. Most hours, less power will be needed. What does the shuttle cost per hour when it is holding for a launch? I think the space elevator will be very competitive. Neil

 

[jmilsom]

Thanks for those excellent links. The more of this I read, the more I feel we are entering a 'nanotech revolution,' and it is is going to change the face of global technology.<br /><br />It is great that each such discovery, as Neil points out, brings the Space Elevator one step closer to viability. <br /><br /><i>harder than diamonds</i> - Wow! <i> Fog-free glass</i> - this has amazing day to day applications - car windscreens that never fog up. It means one day I'll actually be able to buy a pair of fog-free swim goggles that are actually fog-free! <div class="Discussion_UserSignature"> </div>

 

[nexium]

A possibly important application for CNT is discussed in the last (10:50 pm) post titled "windpower at 35,000 feet" in Missions and Launches. Neil

 

[jmilsom]

Another amazing article (I had just finished reading you language-recognition post). That is an incredible breakthrough. I smell a Nobel prize here. This could well revolutionize electronics. <div class="Discussion_UserSignature"> </div>

 

[barrykirk]

Chris,<br /><br />Slight problem with plugging in the climber and using a long electric wire.<br /><br />Ohmic losses will kill you. The longer the wire, the higher the ohmic losses, unless you make the wire really thick and heavy which has other problems. Also what would you reinforce the wire with.<br /><br />Better to have the conductor integrated into the elevator cable itself, but you are still going to have staggering ohmic losses, unless you run the voltage up very high. But high voltages will cause other problems.<br /><br /><br />I would imaging that 15 KV would be the minimum voltage necessary to get any reasonable power. And that will only get you the first 1000KM or so.<br /><br />Sorry, but beamed power is the way to go.