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Diamond Nanothreads Could Support Space Elevator (space.com)
Taco Cowboy writes with news that Penn State researchers have discovered a way to produce ultra-thin diamond nanothreads that could be ideal for a space elevator. According to the report at Space.com, The team, led by chemistry professor John Badding, applied alternating cycles of pressure to isolated, liquid-state benzene molecules and were amazed to find that rings of carbon atoms assembled into neat and orderly chains. While they were expecting the benzene molecules to react in a disorganized way, they instead created a neat thread 20,000 times smaller than a strand of human hair but perhaps the strongest material ever made. ... Just recently, a team from the Queensland University of Technology in Australia modeled the diamond nanothreads using large-scale molecular dynamics simulations and concluded that the material is far more versatile than previously thought and has great promise for aerospace properties.
From the perspective of a space elevator, it's not. Read this paper linked from the article. There's no talk of space elevators, that's just their way to entice the reader into listening to them.
That is to say, the space elevator mention is just clickbait.
As the paper notes, "experimentally measured tensile Young's modulus for SWNTs ranges from 320 GPa to 1.47 TPa with the breaking strengths ranging from 13 to 52 GPa". A material with the density of SWNTs is generally considered to need at least 100-120 GPa irreversible yield strength (less than breaking strength) to make a "practical" elevator (although if you read those proposals it's hard to come across with any conclusion other than that they're being way too optimistic even with those numbers). Note: 13-52 GPa for individual tubes. Ropes of multiple tubes are 1-2 orders of magnitude weaker.
So what about these diamond nanothreads?
Their data is pretty consistent, with graphs showing a clear dropoff and stabilization around 56 GPa. Obviously nm-sized fibers are pretty worthless for the purposes of an elevator, there'd be way too little Van der Walls holding them together into a rope.
Now, these are just simulations. But more often than not real world seems to underperform simulations rather than overperform, so I wouldn't get too optimistic about the real-world greatly exceeding these figures. For example, early simulations of SWNTs said they'd be around 120GPa; few believe nowadays that they can even approach those figures.
But what about the density side of the equation? After all, a material can be weaker, but if it's correspondingly lighter, then that's not a problem. The density is not in the paper, but this cites the tenacity (breaking strength over mass) as 4.1e10^7 N-m/kg. While the yield strength is going to be a bit less than the breaking strength, it shouldn't be too far off - this means that the density should be somewhere less than - but not too much less than - 1,37g/cm^3. That's on the same order as SWNTs, unfortunately.
Short answer? We're still nowhere even remotely close to being even capable of making a space elevator.
Space elevators face such numerous problems anyway (really don't want to have to go into them all) that they're really not a fruitful avenue of pursuit. We'd do far better to direct such efforts to more realistic access methods, such as a Lofstrom loop or variant thereof, which requires no unobtanium and is far more efficient (space elevators lose huge amounts of energy to transmission losses, throwing away a large chunk of the advantage that they gain from bypassing the rocket equation). Active suspension via recirculating kinetic transfer, by one means or another, is something we can do today.
I hate to bring up our imminent arrest during your crazy time, but we gotta move.
Your post is simply incorrect.
1) Rockets are not "quite inefficient". Their Carnot efficiency is usually 80%, net propulsive efficiency around 70% - way better than a gasoline engine (~35%) or diesel engine (40-45%). What they suffer from is totally different: the rocket equation. This mandates exponentially increasing fuel needs to reach a given delta-V, with the exponent proportional to the ISP. But fuel costs have nothing to do with how expensive today's rockets are, we're nowhere near that limit. The Space Shuttle consumed about $2m of propellant to deliver 25 tonnes to LEO, or $80/kg. Using electricity at 100% efficiency and $0,80/kWh it would cost about $0,80/kg to reach orbit. Today's launch costs are about $5k-10k/kg for large launches (the Shuttle was said to be about $18k). So you can see that the fuel costs are just the tiniest fraction, and that it's the engineering challenges of cost-effective production and reuse that are the issue.
2) The "keeping power beaming losses reasonable" is the problem the parent was describing. There is no known way to efficiently transfer power to a small object over tens of thousands of kilometers. Direct transmission isn't even close with conventional conductors, a superconducting line would be many orders of magnitude too heavy, and the cable itself would not be a superconductor, and even if it were its cross section would be way too low. Batteries don't cut it in terms of energy density. And the requirements that climbers be very light precludes nuclear except for the most unrealistically-massive of space elevators. To make RF power beaming remotely efficient over such distances requires a receiving antenna taking up dozens of square kilometers. Laser power beaming means receiving end (solar cell) losses (which even if the solar cells are tuned to a particular frequency you're unlikely to do better than maybe 30-40%) and laser losses (high power lasers are generally in the ballpark of 0,1% efficient; diode lasers can reach up to 25% or so but have far too poor beam quality and are way too weak to be practical). And of course you need a frequency that minimizes atmospheric losses at that.
Perhaps some day power transmission over those distances might become practical, but today it isn't.
This is just the very start of the problems with space elevators, of course. I know space elevators make great books, but they're not practical in the real world. Look into actively suspended structures for your "direct climb to space" needs. They're buildable with today's materials and can get greater than 50% efficiency in energy transfer.
I hate to bring up our imminent arrest during your crazy time, but we gotta move.
Did you RTFA? I'm not normally one to defend /. editors with their crappy proofing and duplicates, but in this case the click bait comes from outside /.
The original article and a few others: