Sapce Elevator NASA competition winner

[dragon]

Kind of cool, only 900,000 prize money but still nice.

LOS ANGELES – A Seattle teams has collected a $900,000 prize in a NASA-backed competition to develop the concept of an elevator to space — an idea spurred by science fiction novels.

The team's robotic machine raced up more than 2,950 feet of cable dangling from a helicopter.

Powered by a ground-based laser pointed up at the robot's photo voltaic cells that converted the light into electricity, the LaserMotive machine completed one of its climbs in about three minutes and 48 seconds, good for second-place money.

The contest is intended to encourage development of a theory that originated in the 1960s and was popularized by Arthur C. Clarke's 1979 novel "The Fountains of Paradise."

Space elevators are envisioned as a way to reach space without the risk and expense of rockets.

Instead, electrically powered vehicles would run up and down a cable anchored to a ground structure and extending thousands of miles up to a mass in geosynchronous orbit — the kind of orbit communications satellites are placed in to stay over a fixed spot on the Earth.

LaserMotive LLC was presented the check by Andy Petro, progam manager of NASA's Centennial Challenges, in a ceremony at Dryden Flight Research Facility on Edwards Air Force Base in the Mojave Desert.

The three-day contest required competitors' vehicles to get to the top, with rewards possible for completing climbs at two levels of speed. LaserMotive could have claimed $2 million if its robot had climbed faster.

The two other teams, KC Space Pirates of Kansas City, Mo., and the University of Saskatchewan's Space Design Team, finished out of the money. Neither of their machines made it to the top.

The fourth Space Elevator Games addressed a baby step in the engineering challenging of the concept, not the larger debates of whether physics, materials technology and economics would ever allow one to be built.

"I think it was an ideal Centennial Challenges competition," Petro said in a telephone interview. "We had students, entrepreneurs and independent inventors. It's a very difficult challenge. It's taken the teams four years for anyone to win."

Thomas Nugent, one of the principals of LaserMotive, said the company believed the contest would demonstrate the concept of "power beaming" — transmitting energy by laser over long distances.

Nugent said there are numerous immediate applications such as providing power to remote areas of military bases or operating electrically powered unmanned aircraft for extended periods.

Nugent said he personally doesn't believe a space elevator would work on Earth but may be practical for the moon or Mars.

"It took a lot of years of hard work by just a great team of people who have understanding families," he said.

link

[Gilthan]

The team's robotic machine raced up more than 2,950 feet of cable dangling from a helicopter.

Powered by a ground-based laser pointed up at the robot's photo voltaic cells that converted the light into electricity, the LaserMotive machine completed one of its climbs in about three minutes and 48 seconds, good for second-place money.

0.559 miles in 0.0633 hours.

At that rate, GEO (22236 miles) would be reached in 2520 hours, like spreading the construction cost of an elevator over payback of 3.5 payloads sent up per year, although that's only a vague ballpark, neglecting perhaps a speed increase at higher altitudes when gravity is less or other differences. Unfortunately each payload would mass only a tiny fraction of space elevator mass, given how the elevator got to be tapered greatly to not break under its own weight, even if making it from expensive materials bordering on unobtainium.

It'd be far easier, exponentially easier for the moon, although a rotating lunar rotovator could allow payloads to be sent up faster than a stationary space elevator, due to vastly more vertical payload speed after pickup.

A lunar rotovator is a rotating tether system designed by Hans Moravec.

The basic idea is that the tether is in lunar orbit at say, 50km altitude, but the tether is more than 50 km long, and spins with a counterweight so that it touches the ground one or more times per orbit. The spin is arranged so that the tip just stops relative to the lunar surface and hence can be used to pick an object off the lunar surface and throw it into space- towards the earth.

This of course takes energy, which would tend to slow the tether, but this can be compensated for catching a similar mass from the earth and dropping it down to the moons surface. This means that it can be used as a transport system.

The main material necessary to build this device is simply Kevlar, it is believed to be well within the realms of current technology; no unobtainium is needed.

http://everything2.com/title/lunar+rotovator

[Sarevok]

Is not a space elevator so far beyond our science that by time we build one we would be sending colonists to other star system ? The requirements for an elevator read like a material from science fiction and its benifits are too negligible to justify enormous technological and resource hurdles.

[RedImperator]

Is not a space elevator so far beyond our science that by time we build one we would be sending colonists to other star system ? The requirements for an elevator read like a material from science fiction and its benifits are too negligible to justify enormous technological and resource hurdles.

If carbon nanotubes could be mass-produced (a big "if"), a space elevator on Earth would be possible, for a fraction of a fragment of a rounding error compared to the cost of interstellar colonization. Even if not, they're still a viable idea on lower-gravity worlds like the Moon and Mars--you could build a space elevator on Mars out of ordinary steel wire, if I recall correctly. Mars even has a miles-high volcano (Pavonis Mons) conveniently located right on the equator.

[The Duchess of Zeon]

Well, the highest point on the equator at Earth is 4,690 meters, in Ecuador. We could probably build the base of a space elevator there with goods being sent to it via a rack railroad of the Lochner type up to the base of the elevator with a regular railroad from the base down to coastal ports for transshipment of goods. I am not worried about the speed, we'd get far more loads up than we otherwise would, and remember that even with carbon nanotubes the weight of the elevator would be enormous. We need to be able to lift tens of thousands of tons of materials in space cheaply each year to really viably exploit our solar system and colonize it in a meaningful way, and that means space elevators (or regular Orion launches. Which I guess would maybe work with some kind of fusion weapon which didn't have a fission core, in terms of viability, but has far more severe problems than a space elevator.

Also remember that this is the first laser-powered wire climbing effort that's succeeded ever, so I'm not sure why people are making definitive statements based on it. The maximum speed of the first automobile--the Benz Patent Motorwagen--was about 10 miles per hour. Are all semi-trucks on the road today limited to 10 miles per hour? Can the Bugatti Veyreon only make ten miles per hour? No, I didn't think so. And we are so definitely at the Benz Patent Motorwagen stage in building effective space elevators.

[Qi__]

I'm glad someone is taking the defense of these guys.

The space elevator idea became viable about 10 years ago. Since then a couple of commercial companies have started a business that will eventually produce working space elevators.
10 years ago they estimated the first space elevator would be launched after 15 years. Still this was wishful thinking, but it will probably in the close future.

The mass production of carbon composite nanotubes was holding it back. The material is strong enough to build a space elevator holding its own weight -and- lift extra tons -and- based on earth, but they could not make the production process steady enough to make a tether that has no weak spots.

However, last week they made a break through, here is a link to the article in nature

About the remark about the climbing speed:
1. These robots were proof-of-concepts, with small resources they were able to build a climber where the laser beam could be steadily aimed at the photo cell, and a climb wheel that holds steady on the ribbon (the future nano tube tether is a ribbon of 3 feet wide and 1/2 inch thick). Real climbers will have stronger laser beams and better motors.
2. The organizer is NASA. Let that fact sink in people. This means its serious business, they have limited budget these days.
3. The higher it goes, the less air resistance and less gravity it has and the climbing rate speeds up dramatically.

If you really want to dig in, here is a link: http://www.spaceelevator.com/

I can tell you this is serious business. It will replace rocket shuttles. You'll see.

[Qi__]

[Alyeska]

Biggest concern about the space elevator is the risk of space junk collisions.

[The Duchess of Zeon]

Biggest concern about the space elevator is the risk of space junk collisions.

Wouldn't that be a fucking anti-lotto event? The chance of any particular orbit resulting in an impact would be less than that of an impact with the space shuttle. That said, we'd have a permanent cable crew in orbit to handle repairs.

My own personal scheme would be to use a very large Orion-type to carry the first strand into orbit, and act as a counterbalance at the top of the cable and basis for a space station there for the receipt of goods. We can probably get away with accepting a couple of Orion launches from Antarctica, and they'd contextually be the equivalent of the SS Great Eastern, useless in her designed role but marvelous for hauling thousands of tons of cable into orbit and then actually lowering it to the Earth while serving as the counterbalance.

The advantage then is that we just use a cable cluster where the chance of losing every single fibre is rather miniscule, and then we can have a couple heavy repair ships in orbit from the moment the cable system has been established which can grapple a damaged cable and support it while repairs are made, if necessary, using engine thrust to keep it aloft.

[Starglider]

The space elevator idea became viable about 10 years ago. Since then a couple of commercial companies have started a business that will eventually produce working space elevators. 10 years ago they estimated the first space elevator would be launched after 15 years. Still this was wishful thinking, but it will probably in the close future.

Similar things have been said about fusion power, nanorobotics and artificial intelligence. Space elevators have some fundamental materials issues to overcome, with no guarantee that throwing money at the problem will work, as well as a whole host of less critical but still serious engineering issues. Then there's the huge startup investment required, and the fact that there isn't a pre-existing market for major lift capability.

The mass production of carbon composite nanotubes was holding it back.

It's not just producing nanotubes. It's producing nanotubes of the right type (single walled) and forming them into a cable with sufficient cross-linking to carry the load. Raw nanotubes are slippery things; you can functionalise the tube walls, but that's difficult to to consistently and without compromising structural strengths. Producing short nanotubes in bulk has lots of useful applications (e.g. electronics), but nanotube cables are another thing entirely.

However, last week they made a break through, here is a link to the article in nature

As far as I can tell that will only speed up assembly if a sufficiently strong and reliable bonding technique is found.

1. These robots were proof-of-concepts

To be sure, building the climbers is one of the easiest parts of the problem.

[starslayer]

Well, the highest point on the equator at Earth is 4,690 meters, in Ecuador. We could probably build the base of a space elevator there with goods being sent to it via a rack railroad of the Lochner type up to the base of the elevator with a regular railroad from the base down to coastal ports for transshipment of goods. I am not worried about the speed, we'd get far more loads up than we otherwise would, and remember that even with carbon nanotubes the weight of the elevator would be enormous. We need to be able to lift tens of thousands of tons of materials in space cheaply each year to really viably exploit our solar system and colonize it in a meaningful way, and that means space elevators (or regular Orion launches. Which I guess would maybe work with some kind of fusion weapon which didn't have a fission core, in terms of viability, but has far more severe problems than a space elevator.

An ocean-going base off the Galapagos Islands is a better choice. An ocean-going platform is much easier to move, allowing it catch and anchor the preliminary cable, and then to move out of the way of weather hazards that might pop up. A good hurricane would destroy the cable, and possibly even lightning strikes or other high winds could do the job, and while the Galapagos location minimizes these dangers, it does not eliminate them. Besides, most viable designs require a cable that is about 133,000 km long, IIRC; 4.5 extra km is not going to matter much at all.

Space junk and meteoroids are in fact a real danger to the cable, owing again to its great length and geostationary orbit. A movable base would enable it to move out of the way of the larger bits (~1 cm in diameter and up), which could potentially destroy it before we have had a chance to reinforce it.

The advantage then is that we just use a cable cluster where the chance of losing every single fibre is rather miniscule, and then we can have a couple heavy repair ships in orbit from the moment the cable system has been established which can grapple a damaged cable and support it while repairs are made, if necessary, using engine thrust to keep it aloft.

A better idea would just be to send climbers up the cable, laying down another layer as they go; this would be enough to counteract any micrometeoroid damage.

[Alyeska]

Wouldn't that be a fucking anti-lotto event? The chance of any particular orbit resulting in an impact would be less than that of an impact with the space shuttle. That said, we'd have a permanent cable crew in orbit to handle repairs.

The space elevator would transit multiple orbital plains vastly increasing its likelihood of being hit. And space is only getting more crowded at the moment.

[Sarevok]

Lets not forget winds. Even baloons grounded with cables sway a lot in high winds. How do you keep the delicately fragile construct of a space elevator from ripping itself to pieces in a storm ?

[The Duchess of Zeon]

Because the cable is literally thousands of kilometers long, so it has huge amounts of flex in it, especially if it's counterbalanced by a platform that has engines which can provide thrust to counter any atmospheric disturbances on the ground. A nuclear space-station with some ion engines would do fine for keeping the forces balanced in the necessary way to keep the cable in place, for example. Anything which can stay together over its own weight over such distances would not end up screwed by relatively minor forces on the very lowest part of the cable.

[Mayabird]

Isn't that area of Ecuador also an unusually not-often-hit-by-lightning-or-other-storms region? That would make it an even better location for the first space elevator by making things that much easier.

[Junghalli]

We need to be able to lift tens of thousands of tons of materials in space cheaply each year to really viably exploit our solar system and colonize it in a meaningful way, and that means space elevators (or regular Orion launches. Which I guess would maybe work with some kind of fusion weapon which didn't have a fission core, in terms of viability, but has far more severe problems than a space elevator.

You forgot mass drivers, which are my bet. Sikon wrote up a good post on how mass drivers are probably easier to implement than space elevators and can theoretically send up much greater volumes of stuff here.

Wouldn't that be a fucking anti-lotto event?

Not if you plan to put your space elevator on the equator. Pretty much every stable low orbit I can imagine is going to cross the equator at some point.

The chance of any particular orbit resulting in an impact would be less than that of an impact with the space shuttle.

The space shuttle does not present a target thousands of kilometers long.

[Sarevok]

So what materials are known that have required properties for a space elevator ? Can they be produced in suffficient quantities ? Without a firm answer to these questions no one can claim a space elevator is a sound proposition in the forseeable future.

[GrandMasterTerwynn]

So what materials are known that have required properties for a space elevator ? Can they be produced in suffficient quantities ? Without a firm answer to these questions no one can claim a space elevator is a sound proposition in the forseeable future.

The only material strong enough and light enough would be a strand made from carbon nanotubes. Extremely long carbon nanotubes, as in orders of magnitude longer than we've managed to produce so far. If we can build those, then a space elevator becomes a feasible proposition. Not one that is doable without a preexisting orbital infrastructure, mind you; since you'll need to build a fairly large anchor station (preferably on a captured asteroid. Won't that be a fun idea to sell to the public: "You know how we've spent the last century telling you how dangerous asteroids are? Now we want go get a big one, and move it into Earth orbit, so we can use it to anchor our space elevator,") and some schemes involve manufacturing the cable in space, and lowering it down to Earth (or manufacturing the cable on Earth, lofting a thin leader cable into space, and using that to haul up a thicker cable suitable for small loads. Then, you'd eventually haul up, or haul down the full-thickness final cable.) This ignores the network of space-based lasers you may need to sweep debris from the path of the elevator cable. This means it also has considerable political challenges to overcome, since a full-scale orbital elevator would require an effective, united, planetary government to put into place.

[Gilthan]

Since almost any system costs billions of dollars, really inexpensive space access requires a system sending up many thousands of tons a year to give high payback. That in turn requires either:

1) Many payloads a day.

Bad economics: The Space Shuttle, launched only every several months.

Bad economics: Not only the prize-winning elevator climber here that'd take proportionally 3.5 months to climb the 22000 miles to GEO but even a cable climber 10 times faster.

Good economics: Anything with rapid turnaround, whether a hypersonic SABRE aircraft-rocket system if successfully obtaining frequent flights like an airline, a mass driver dropping a new one-ton projectile into its bore and firing it every minute, or whatever means are used.

or

2) Really huge payloads, like Orions or Sea Dragons where the first handful of launches alone put up thousands of tons.

Of course, there's the chicken-and-egg problem. Space access is expensive, so we do little in space. Yet there's no possible way, for example, to have $10 or even $100 a pound launch to space when sending up a small amount. Conducting a whole space program for $10 million to obtain $100 a pound cost when launching 50 tons would never happen. A $100 billion space program obtaining $100 a pound cost by sending up 500k tons could theoretically happen.

So what materials are known that have required properties for a space elevator ? Can they be produced in suffficient quantities ? Without a firm answer to these questions no one can claim a space elevator is a sound proposition in the forseeable future.

Kelvar would break under its own weight in 160 miles length, more if highly tapered but with exponentially more mass and cost. The best commercial carbon fibers are roughly similar strength to weight ratio at best.

Carbon nanotubes are strong but still haven't even beat conventional carbon fibers so far in the real world when made into long lengths of composite or cable, despite their heavily-hyped enormous bond strength between some individual atoms. An example, the measured strength of some hundred-meter length carbon nanotube composite fibers:

http://www.darpa.mil/dso/thrusts/matdev ... ommAll.pdf

A space elevator to GEO of 22300 miles nevertheless doesn't require 140 times the strength to weight ratio of kelvar. The combination of gravity decreasing substantially beyond the first few thousand miles altitude and tapering reduces requirements. It still needs dozens of times higher performance than kelvar or any other existing real-world cable, though.

So, if in some future year, you saw the performance of bulletproof vests, high-strength aerospace composites, and other products become dozens of times greater than today, then you could conclude that a space elevator was approaching technical possibility.

Until then? Not so much.

Even if that day ever occurred, technical possibility still wouldn't be the only issue. Economics is everything, not just compared to today's rockets but versus alternatives for that much expenditure.

[dragon]

So what materials are known that have required properties for a space elevator ? Can they be produced in suffficient quantities ? Without a firm answer to these questions no one can claim a space elevator is a sound proposition in the forseeable future.

Well the desired strength for the materials in space elevator are about 62GPa

Fiber materials such as graphite, alumina, and quartz have exhibited tensile strengths greater than 20 GPa (Giga-Pascals, a unit of measurement for tensile strength) during laboratory testing for cable tethers. The desired strength for the space elevator is about 62 GPa. Carbon nanotubes have exceeded all other materials and appear to have a theoretical strength far above the desired range for space elevator structures. "The development of carbon nanotubes shows real promise," said Smitherman. "They're lightweight materials that are 100 times stronger than steel."
snip
Carbon nanotube (CNT) is a new form of carbon, equivalent to a flat graphene sheet rolled into a tube. CNT exhibits extraordinary mechanical properties: the Young's modulus is over 1 Tera-Pascal and the estimated tensile strength is 200 Giga-Pascals. [more information]

old info

As for materials that match or exceed that you have CNT, DWNT (double walled nanotubes), TWNT (tripled walled nanotubes) plus several other types of nanotubes all of which has drastically different properties.

granted these are therotical maximums for CNT.



as for tensile strength of mutiwalled CNT I read a few articles where they were able to get almost 100GPa even thought the theortical max is almost 1TPa.
I'll see if I can find the article again, assuming I remember it right.

[Gilthan]

Take carbon nanotubes that have some atomic bonds of 60 GPa strength (63 GPa reported, 120-150 GPa theoretical), make them into a long fiber in real life, and results are such as the 1.6 GPa of the 100-meter length 50 micron diameter CNT composite fibers:

http://www.darpa.mil/dso/thrusts/matdev ... ommAll.pdf

Graphite crystals can be 150 GPa strength, hundreds of times the strength of aluminum. See
http://resources.metapress.com/pdf-prev ... ze=largest

So should we conclude that future aircraft and rockets will have many structural elements with less than 1% the weight of today's aluminum parts, or is there something wrong with the kind of logic that'd lead to such a belief?

[Qi__]

The commercial companies wanting to be in the space elevator business didn't start with space elevators.

They started with setting up spinoff activities like fabrication of high strength fuel tanks from carbon composite nano tube fiber.

Hydrogen fuel, because its only byproduct is steam, should be the ultimate in green alternatives to fossil fuels, but it hasn’t delivered on its promise yet because of one enormous stumbling block, storage. Now a team of chemical engineers at the University of Massachusetts Amherst has developed a computational model that shows that carbon nanotubes may offer a surprising solution. Results are presented in the current online issue of the journal, Applied Physics Letters.

“Hydrogen storage has been a huge problem in the energy field for the past 10 years because no one has been able to demonstrate a truly viable storage medium. We’ve shown that it’s possible to achieve hydrogen storage capacity up to 8 percent by weight using carbon nanotubes. This is an outstanding level, higher by 1 percent than the 2010 United States Department of Energy target for on-board hydrogen storage systems,” Maroudas adds. “The method we propose may lead to breaking the bottleneck.”

It's a computational model. So we're still on the 'promising' level.

[Gilthan]

Indeed carbon nanotubes are a promising area of research for a variety of applications.

I would point out, though, that Azo Cleantech didn't get higher hydrogen storage by a breakthrough in the GPa strength of bulk material but rather by a hydrogen chemical absorption process (chemisorption). That is fine for their application (if nanotubes become cheaper), but it is not a breakthrough in general structural applications, not changing how far nanotubes are from making bulletproof vests a few percent the weight of kelvar or making space elevators.

Googling for a moment to look at the rest of the news release and noting its end:

http://www.azocleantech.com/Details.asp?newsID=6818

Specifically, Maroudas, his graduate student Andre Muniz and their collaborator M. Meyyappan, chief scientist for exploration technology at the Center for Nanotechnology at NASA Ames Research Center, Moffett Field, Calif., show that proper arrangement of carbon nanotubes can overcome hydrogen transport limitations in nanotube bundles. It should also prevent ineffective and nonuniform hydrogenation, which is caused by nanotube swelling due to chemisorption of hydrogen atoms on the nanotube walls.

If one were to think of carbon nanotube bundles as something like a toothbrush, one strategy that Maroudas and colleagues recommend for holding hydrogen atoms most efficiently is that the brush arrangement should not be too dense. If it is, when the tubules swell they’ll block efficient passage and diffusion of the hydrogen, Maroudas explains. In addition to an optimal bundle density, further improvement can be achieved by optimizing the individual nanotube configurations to limit their swelling upon hydrogenation.

Following this approach should result in one hydrogen atom being able to chemisorb onto — form a chemical bond with — each carbon atom of the nanotubes, leading to 100 percent (atomically) storage capacity, he adds. This chemisorbed hydrogen, bound to the surface, can then be easily released by applying heat.

Maroudas says, “We propose recipes that will be very easy for others to try, by which carbon nanotubes can be arranged to accomplish practically 100 percent storage atomically, which is nearly 8 percent by weight. You can’t get any greener than hydrogen as fuel, and if the experiments we envision lead to new technology that’s economically viable, that’s as good as it gets.” This work was supported by a National Science Foundation grant and a Fulbright/CAPES scholarship to Muniz.

[dragon]

question on this

CNT exhibits extraordinary mechanical properties: the Young's modulus is over 1 Tera-Pascal and the estimated tensile strength is 200 Giga-Pascals.

Do we only care what the tensile strength is and not the young's modulus, for the properties of a space elevator use?

edit - kind of neat and usefull.

Scientists at Rice University on Monday unveiled a method for manufacturing carbon nanotubes on an industrial scale.

Based on an existing method for producing plastics, the process involves dissolving large amounts of nanotubes in an acidic solvent for processing and then later spinning them into a usable filament. That, scientists say, may makes the production of nanotubes as efficient as the production of plastics.

“The reason grocery stores use plastic bags instead of paper, and the reason polyester shirts are cheaper than cotton, is that polymers can be melted or dissolved and processed as fluids by the train-car load,” said Matteo Pasquali, coauthor of a research paper on the subject and professor at Rice University. “Processing nanotubes as fluids opens up all of the fluid-processing technology that has been developed for polymers.”

Scientists say the discovery could aid in the mass-market use of carbon nanofibers, which can be used in the production of next-generation semiconductors and strong, durable composite materials.

Results of the nine-year program will be published in this week’s edition of the science magazine Nature Nanotechnology.

link

[Surlethe]

Split Qi__'s comment. Put more thought - or, God forbid, some research - into your posts.