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CURRENT STATUS (5/1)
Finally starting to rev up towards an exciting 2010 sequel, power beaming and tether
Details soon... |
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For the obvious reasons, I invariably get too busy to blog exactly when things get interesting...For the latest word, and for a wider perspective on all things Space Elevator, you can alway turn to Ted Semon's most excellent Space Elevator Blog - www.SpaceElevatorBlog.com
The TRUMPF Group is one of the world's leaders in the field of production technology - machine tools, material processing, high power lasers, electronics and in medical technology.
TRUMPF took a natural interest in the Power Beaming challenge, and they are providing their 8 kWatt top-of-the-line laser system for use by teams KCSP, USST, U Michigan, and NSS.
Find out all about TRUMPF's laser systems at www.trumpf-laser.com
Mackey International is an aviation consulting firm specializing in aviation safety, risk management, accident investigation, air carrier certification and safety/compliance audits.
With Mackey's experience and expertise, Spaceward was able to put together an operations plan that satisfied the requirements of NASA's aviation safety review - not an easy feat given that a rotorcraft-tether configuration such as ours has never been flown before.
Find out all about Mackey International's capabilities at www.keithmackey.com
Bitter WHAT?! Exactly. This is what Nic DeGrazia, Creative Director of Bitter Jester Creative, told me about their company's name. Nobody ever forgets it.
The same is true about BJC's work. Winners of Telly and Hermes awards, their work brings out the human element in every story.
BJC are continuing their 2-year project of documenting the games, now in its third year. Find out all about them at www.BitterJester.com
Dynon Avionics designs, manufactures and distributes a growing line of affordable glass cockpit avionics. Operated by aviation enthusiasts, Dynon utilizes the very latest state-of-the-art technologies to create modern avionics products with an emphasis on lowering prices and enhancing reliability.
For the games, we had to assemble a special helicopter station-keeping system that will allow the pilots to position the helicopter accurately even when flying at 4300' AGL. Dynon components were our first choice, and are doing the job beautifully.
Find out more at www.dynonavionics.com
Lockheed Martin is a global security company that employs about 146,000 people worldwide and is principally engaged in the research, design, development, manufacture, integration and sustainment of advanced technology systems, products and services.
Find out more at www.LockheedMartin.com
Since its inception in 1962, OMEGA has grown from manufacturing a single product line of thermocouples to an established global leader in the technical marketplace, offering more than 100,000 state-of-the-art products for measurement and control of temperature, humidity, pressure, strain, force, flow, level, pH and conductivity. OMEGA also provides customers with a complete line of data acquisition, electric heating and custom engineered products.
Omega has been sponsoring the games with various equipment such as large format displays and load cells since 2006.
Find out more at www.omega.com
SPIE is an international membership society, serving scientists and engineers in industry, academia, and government, as well as companies producing leading-edge products. SPIE constituents work in a wide variety of fields that utilize some aspect of optics and photonics, which is the science and application of light. More specifically, optics is a branch of physics that examines the behavior and properties of light and the interaction of light with matter. Photonics is the science and technology of generating, controlling, and detecting photons, which are particles of light.
Find out more at www.spie.org
While NASA sponsors the $4M prize purse, Spaceward does not receive any of it - we fund our operations from donations and sponsorships from people like you.
Our sponsors and donors are people who believe in the infinite promise (and cool factor) of the Space Elevator, and would like to be associated with it and help in its development.
You can see the media impact we've had to date here, and with our NASA TV coverage this year (available on DirecTV #238) and our livecast we will reach millions of people with our (and your) message.
To see the impact we've had on technology education, our best advertisements are our student teams, who started out as curious high-schoolers and undergrads, and by now have built cutting-edge photonics systems worthy of NASA itself!
“New ideas pass through three periods: 1) It can’t be done. 2) It probably can be done, but it’s not worth doing. 3) I knew it was a good idea all along!” — Sir Arthur C. Clarke
“We predict too much for the next year and yet far too little for the next 10.” — Neil Armstrong
The other side of the Feasibility Condition is the tether side – the one that corresponds to our Strong Tether challenge.
To recap, we are offering a prize of $0.9M for a tether sample that has a specific strength of 5 MYuri, and an additional prize of $1.1M for a tether sample that has a specific strength of 7.5 MYuri.
For context, today’s materials perform at 2.5 – 3 MYuri at best, and to build a Space Elevator we need material that is 25 – 30 MYuri. (A MYuri is the name we gave the SI equivalent of N/Tex, or GPa-cc/g)
A visual guide to the task ahead
Actually, we’ll be more comfortable (and the Space Elevator will function a lot better) with a ~35 MYuri material, but this is the bare minimum that we need. Keep in mind that successive 50% improvements in material strength are very large steps, but that we already know that CNT molecules are measured at ~50 MYuri, and fabricated CNT micro-bundles have been produced by several labs at 10 MYuri, so this challenge is not impossible.
It is important to note that while in order to win the prize we require the core metric of specific strength, we do not require the tether samples to be made in a way that is scalable, profitable, repeatable, or durable. We do not care if it took a whole year of undergrads working around the clock, and the sample is the best of 100 samples that were made. This makes the prize very attractive to CNT research labs, since we’re offering a substantial amount of money at a stage where investors are still (rightfully) shy, since the tether is still far far from being a sellable product.
To date, we’ve had two Carbon Nanotube tether samples at the games.
In the 2009 games, the University of Shizuoka team, led by Yoku Inue, entered a CNT tether loop (our second ever).
The tether sample was made out of Carbon Nanotubes that were grown as an aligned nanotube “forest” on a flat substrate, then pulled into a loosely aligned “sliver” and spun into a thread.
The Carbon Nanotubes themselves are short in everyday terms (a tenth of a millimeter) but still represent an aspect ratio of more than 10,000:1. The tether was then looped around to create a closed flat tape, with cross-over lines similar to Brad Edward’s proposed ribbon construction of a Space Elevator.
Being their first effort at a macroscopic tether, it failed very early, pretty much separating between the micro-fibers.
In the 2007 games, team delta-X representing Nanocomp Inc, presented a tether sample made out of Carbon Nanotubes that were grown in an aerosol-like phase and spun out directly from this “black smoke” in a way reminiscent of a cotton-candy machine. Delta-X’s tether was a very recent result, and so they did not have the ability to form a closed loop just yet. Instead, the tether was tied in a knot to form a closed loop, and as expected, when pulled, the knot slipped.
Both tethers failed at the macroscopic level, very far from the strengths achieved by the individual CNTs or even the CNT micro-bundles that constitute them
On the one hand, just having these samples and talking with the teams gives us a good indication that the challenge is having its desired effect and is drawing research teams to look into tensile strength of CNTs, which is otherwise one of the harder challenges in the field, and one offering longer-terms rewards.
On the other, we’re hoping that in the next games we’ll be able to at least show performance levels comparable to the Kevlar or Zylon type tethers that are out there today.
Spaceward’s next goal is therefore to aggressively pursue the CNT labs out there – we think that the timing is about right, since CNTs are now produced by an ever larger set of universities, and the production of a 2-gram carbon nanotube tether, while incredibly impressive in last year’s terms, will no longer be a novelty in 2010.
One of the results of the Space Elevator Feasibility Condition is a lower bound on the power density of Space Elevator vehicles.
Power density is a measure for how powerful a motor system is in respect to its mass. In the case of a Space Elevator climber, the system mass must include the motor, the PV array, any cooling systems, and structure mass used to aid locomotion – basically everything but the cargo hold.
For a Carbon Nanotube tether that is 30 MYuri strong, and a characteristic time constant (CTC) of 1 year (Confused? Curious? Read the paper!) the Feasibility Condition requires that the climbers will have a power density of at least 1.0 kWatt/kg.
So where do the competition requirements stand in respect to this?
It is easy to show that when moving straight up, the power density of the climber is directly proportional to its speed (mgv/m), and so a 5 m/s speed in 1 g gravity corresponds to 50 Watt/kg, or about 5% of a real Space Elevator climber.
So how difficult is it to improve this performance by a factor of 20?
Not impossibly so.
The climbers built by the teams are designed to be rugged, and even at 5 m/s are having to deal with significant wind resistance. Even though they are designed to be lightweight, the actual panels on a Space Elevator climber will be much lighter. In space, lacking wind, and lacking cooling air, the PV panels will look more like Saran Wrap or Aluminum Foil than like real “panels”.
The PV panel shown below was manufactured by DLR in Germany, with the intent to be used in space. It is so thin and large (see the people in the back for scale) that it will never survive even the lightest winds on Earth and can fit into the little box at the center (from which it was deployed). In space, however, it would be the ideal building block for a Space Elevator climber, and even today this panel performs at several times the power density we need for a Space Elevator climber.
One of the nice things about this panel is that it is designed for Solar radiation, which means that after the initial laser-boosted stages of the climb, the climber can make the rest of the way (about 80% of it) using sunshine alone, which makes it easy to drive several climbers simultaneously.
Electric motors that operate at the kWatt/kg range exist today (though they are not super efficient), but ironically, the same CNTs that make tethers stronger, stand a very good chance of reducing the weight of electric motors by replacing the metallic windings that are in them.
So to conclude – on the power side of the feasibility condition, the building blocks are there – the solid state lasers, the PV receivers, the advanced motors and power electronics. Not ready to be assembled within a year, of course, but certainly within reach in the 10-year outlook.
One week to go – time to take stock. From Spaceward’s point of view, things are going well. Virtually all of the pieces are already in place or quickly getting there. We’ve had a good amount of practice setting up the racetrack, and we’ll get time to practice it again just before the games.
Regrettably, Team NSS had to withdraw at the end of last week as they were running out of money (and time) to get everything ready for the games. A shame really, since they were able to put together a remarkable system in a relatively short amount of time. (If you recall, they were trying to rebound from a loss of a major component in their system).
Team Overview:
We’re thus left with three teams: KCSP, USST, and LM.
This would be a good time to make a little comparative study among them. The formulation of the power beaming problem (The range, the fact that the receiver is mobile) drove all the teams to use laser-based systems, but beyond that, the teams are very different from each other.
Perhaps the most visible difference between the teams is not in their technology, but in their backgrounds (and character). Since none of them are newcomers, we know a thing or two about them:
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Lasermotive (LM) is our “industry” team, led by long time laser industry expert Dr. Jordin Kare, and really almost doing this as a hobby. Another of their hobbies is this. They are based in Seattle, and one look at their sponsor list makes it clear that they are a force to be reckoned with. Laser motive is on its second year at the games, having made their debut in 2007 |
USST is our university student team (Team Captain is Bill Voss, also from Seattle, and the students are from the town of Saskatoon, Saskatchewan), except that nothing about it is typical of a student team – they are organized, highly professional, calm and collected – and have outperformed all other teams in all previous competitions so far. USST is the most experienced team at the games, having participated in all challenges since 2005. |
Kansas City Space Pirates (KCSP) are our robotic-club hobbyists, except (guess what…) nothing about them says “amateur”. Their engineering is superb, they have recruited a top-notch panel of consultants, they are consistently the most prepared team, perform the most detailed testings and rehearsals, and their attention to detail is unmatched. Team Captain and chief engineer is Brian Turner, and they are based in Kansas City, MO. This is KCSP’s third appearance at the games. |
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Technically, the teams ended up spanning the gamut in practically every trade-off in the design space: We have different laser wavelengths, different PV technologies, different beam intensities, different thermal designs, different tracking and aiming mechanisms…
(Another reason to miss NSS, btw, since they have settled on yet another operating area, completely different in all respects from each of the other three)
I cannot yet give up specific information, but I can guarantee to you that we have a very good race coming up. None of the teams is a clear winner by any stretch of the imagination. All three are very capable, and all three are shooting for the 5 m/s prize level.
Break-downs and other unforced errors notwithstanding, if the teams get to fully exhaust their capabilities, it will be very interesting to see which system ends up on top. Having invested two years and a lot of personal funds into the development of their systems, I truly hope all three make the prize threshold.
We will be able to divulge much more about the technical aspects of the systems during the games, but until games day (11/4), some cards need to remain face down. Maybe we’ll some more information leak out as the week progresses :)
Next to “Why don’t you just use a balloon”, this has got to be the question that gives me the most heartburn.
Actually, let me correct that – the first question is a valid question, to which I have a valid answer – it’s the use of the “just” in front of the question that is the cause of agitation, since it implies a certain level of ease and simplicity, and hence an implied “why are you making this so complicated…” – but I digress.
Am I sure this is going to work? Of course not. Nobody is less surprised than I am when things that I build don’t work right off the bat. And by the same token, nobody is more surprised than I am when they do… Really.
First, there are mistakes. In a perfect world, most are avoidable, but that does not mean they are indeed avoided. Second, there are unknowns. Some aspects of the system are too difficult to model or calculate, and so have to be tested out. Then there’s the human element, and finally there’s just luck. (In 2007 we got rained out, almost snowed out, in Salt Lake City…)
Our first test flight in June failed due to an engineering mistake. This was compounded somewhat by a human element issue that led us to believe that a different aspect of the system, which was being tested, actually worked well.
In our second test flight, we found out the hard way that this second aspect is actually not working well at all, and as a result had to fall back, regroup, and demonstrate we’ve solved all the issues.
We made major changes, which I’ve covered in previous posts, and went to perform test flights in Olympia, Washington. We’ve flown the 1 km vertical racetrack eight times now (8 successes out of 8 tries), and are pretty confident we’ve got it down. Yet we haven’t done it at Dryden, and perhaps we were only 8-times lucky… I hope not!
The teams are also confident. Their task is more difficult than Spaceward’s. Just like with our vertical racetrack, they went through several design iterations in order to get their power beaming systems ready, and almost by definition, each iteration except possibly the last one ended in “failure”, or in other words – in figuring out something new.
Collectively, they have tested their systems horizontally, vertically, on test-stands and on treadmills. They beamed power to a kilometer, and extracted more than they need to win the 5 m/s prize money. They tracked model cars, people, bicycles, cars, ultra-lights, and even canoes. They simulated real runs. They think they’ve got it down. Yet none of them has climbed 1 km vertically.
So there. One week to go, and there are plenty of reasons to be confident. But are the teams already spending their prize money? I hope not.
Stay tuned!
One of the nice things about Near Infra-Red light is that it gets picked up by regular cameras, showing up as some combination of colors, unique to each camera. In the case of my camera, it shows up as this pink-purple hue. To the naked eye, the climber seems unlit.
For more videos from this test session, check out the Space Elevator Blog (”There’s cool, and then there’s Über-Cool”), especially the last video, where Ted’s Maniacal laughter reveals his true nefarious character – who knew.
(The test was conducted at TRUMPF’s facilities in Detroit – they make the cool lasers that put your car together.)
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 Robert Winsor, NSS's Laser man, and Nic DeGrazia, our filmographer in residence, observing the NSS climber during the power test. |
 NSS's TPV array |
Moving to photovoltaics, NSS settled on a PV technology called TPV – Thermal Photovoltaics. These cells are optimized to operate with thermal IR radiation (longer wavelength than TRUMPF’s NIR 1030 nm beam) but have acceptable performance at this wavelength as well. More importantly, these cells can work with high light intensities, which means that you can get more power out of a smaller (and thus lighter) array, if only you can get the transfer the excess heat away from the cells.
What this calls for is a good heat exchanger – and this turned out to be the highlight of the day.
Check out the images of the climber. The TPV cells are completely immersed in acetone (4 ounces) which is vigorously boiling away under the heat load of the beam, completely evaporating every 15 seconds – only to be continuously captured by the bags and dripped back down onto the cells.
Acetone was chosen since it has the lowest boiling temperature, and so will be most effective as the working fluid. This is a basically a cooling tower (or heat pipe) – something that was used by Centaurus Aerospace back in the 2005 games – using water in vacuum, in their case. The acetone solution is a lot lighter, and yes – more flammable.
We’ve looked into this issue, and we recognize that there are failure modes under which the system can develop a leak, but we feel that a) the acetone is far removed from any spark sources, b) there is only a small amount of acetone in the system, and c) there is no place for leaking acetone to accumulate, and so the consequences of an acetone leak are acceptable. We will also be monitoring the temperature of the PV receiver, and if we see it rising above the boiling point of acetone, we will know that the acetone is depleted and the climb is over.
So after observing the climber operating under full laser power, and with some modifications required, we’ve decided to ok the design, and allow NSS to catch up and participate in this year’s challenge.
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One of the nice things about having multiple teams is that you get to see different ideas at work, and NSS is definitely not short on ideas.
Their first climber design featured a thermal (rather than photovoltaic) receiver, based on a Stirling engine. (Stirling engines are high efficiency engines often used for solar power generation) Stirling engines are a difficult proposition for a Space Elevator climber, since they typically weigh a lot more than a PV panel, and so NSS had to design and manufacture their own engine – and it is indeed a beauty. Using Helium as the working fluid, this engine also uses a transparent cylinder head in order to get the laser beam directly into a thermal absorber that is placed inside the cylinder – a perfect way to avoid the latency associated with the thermal mass of a regular absorber plate.
The problem NSS ran into was with properly sealing the engine while keeping the weight down. Anyone who’s ever worked with Helium knows how difficult it is to seal – it is a noble gas, and so is monatomic, which means its molecules are really small, and they get around most seals.
The other problem faced by thermodynamic engines is that while they are able to capture 100% of the energy of the beam (unlike the 30-50% of PV cells) they have to waste a good fraction of it at the heat exhaust side, and this gets worse the hotter the exhaust is. Which means that a thermodynamic engine needs to be coupled to an efficient heat exchanger – something that NSS started to design as well.
As it turned out, NSS was not able to solve the He sealing issue, and started working fast towards a photovoltaic “plan B” climber. However, not all of the effort was wasted – the heat exchanger design turns out to be very important in keeping their PV cells cool – more on that on the next post.
As a side note, Bert Murray and Matt Abrams have vowed that if the prize money is not awarded this year, they will solve the Helium seal issue and be back next year with a working Stirling climber.
The power beaming games are now scheduled to be held on the week of 11/2 at NASA’s Dryden Flight Research Center at Edwards Air Force Base near Mojave, CA.
The first two days of the week will be dedicated to set-up, testing, and calibrations, and the first competitive climb will take place on Wednesday, 11/4.
Each team will get one 45-minute climb window per day, and we will repeat the process over 3 days to make sure each team can achieve the best score they are capable of.
For media inquiries, please contact Alan Brown (alan.brown-1@nasa.gov)
This is going to be exciting. We are well rehearsed, having practiced setting up the 1-km vertical raceway 8 times now (with no problems), and seen one battery-powered climb to the top. Still, there’s zero room for errors, and so my state of mind right now is “confident, but scared $%&^less”. As it should be, really – a lot is riding on getting this right.
This is the place to acknowledge NASA Centennial Challenges and NASA Dryden’s commitment to the games. As in any ground-breaking project, progress is not always smooth, and we appreciate the backing we’ve received.
In addition, we should acknowledge the backing we have from TRUMPF, the tremendous help we got from Northwest helicopters in Olympia, the guidance of Mackey International, Dynon avionics, and Bitter Jester Creative – we’ll get this done with a little help from our friends.
More details soon -
Ben
As they turn into the final straight, KCSP, LM, and USST (in order of qualification) leading the field, NSS is opening up and is barreling down closing the gap.. yeah, ok, horse race calling is not my thing, I should keep my day job.
To the point – Team NSS Bert Murray, Captain) has used the delay in the games to their advantage, and have notified us a couple of weeks ago that they are ready to try to qualify. (NSS originally took a hit when sponsorship of a major part of their hardware fell through)
We are expecting to finalize the competition date any day now, and so NSS has really cut it close. We’ll be traveling to the TRUMPF facility in Detroit early next week to witness the qualification, which will involve a demonstration of the transmitting and receiving optics operating at full power, tracking, reflection measurements – 2 days of testing overall. (we did something similar, if you recall, with LaserMotive about 3 months ago.)
Since Chicago is practically next door, both Ted Semon of the Space Elevator Blog and Nic Degrazia of Bitter Jester Creative will come over to watch and report.
Expect some preliminary reporting on Monday, and an Aye or a Nay late Tuesday evening then.
Meanwhile, we’re working hard on finalizing the date for the games – real soon now! I will of course let you all know just as soon as I find out myself.
