Tag Archives: lasermotive

News, Science, Transportation

Space Elevator Race Still Waiting for a Super Strong Cable

You might think the hard part in inventing a space elevator would be the motor, but in practice the sticking point has turned out to be the cable. At the 2012 Space Elevator Conference held at Seattle’s Museum of Flight, the Strong Tether Competition was postponed. The organizers say they weren’t able to give participants enough time to prepare for the conference, but that there will be a 2013 Strong Tether Challenge.

NASA has been offering a $2-million prize to the person who can “exceed the strength of the best available commercial tether by 50 percent with no increase in mass,” but as of 2011, the competition had gone five years without a winner, despite incremental advances being made.

In 2009, I spoke with LaserMotive’s Jordin Kare about their laser-powered climber’s world-record pace, which netted his team a $900,000 prize, but the climber challenge had ended up using a 4300-foot, 3/16-inch steel cable, held aloft by a helicopter. It was emblematic of the gap in development.

Despite all of the hype about the tensile strength of carbon nanotubes, CNTs have remained frustratingly resistant to being woven together in strength at length, which is what needs to happen if the space elevator is to travel non-nano distances. (It’s enough to make people turn to boron nitride nanotubes.)

On the other hand, Space Elevator Blog has a picture of a cassette-tape-style CNT braid that shows you it can be done. If you think about the whole history of rocket flight, this kind of year-over-year progress is staggering. It helps to keep perspective: Yes, the space elevator would need to climb more than 62,000 miles of “cable” to climb, but as David Horn, of the International Space Elevator Consortium (ISEC), reminds you, there are 80,000 miles of cable in the Golden Gate Bridge.

In July, Horn explained the concept of the elevator program, and its development to Forbes, predicting ocean-based elevators (they need to be able to move to avoid objects in orbit) that can carry 20 tons.

As the BBC’s Richard Hollingham mentions, the only thing crazier than a space elevator is the idea of using hugely expensive rockets instead. Modern-day rocket launches, when they work, run about $16,700 per kilogram. “Estimates suggest that the cost of sending cargo into space,” writes Hollingham, “could plummet to around $100 per kilogram” with a space elevator.

At this year’s conference, part of the buzz was around a Kickstarter-powered lunar elevator from LiftPort. The idea is to leapfrog to the easy part: A lunar-based elevator doesn’t have to climb out of Earth’s gravity well, so the cable it climbs can be constructed from “off-the-shelf” materials available right now. Rockets would still be need to get materials into space, but you could build a lunar base without the hassle of landing. And lunar bases are, let’s face it, very cool.

The initial Kickstarter goal was $8,000, but it had raised $62,000 by the time of this Scientific American article. (It’s at $67,000 with six days to go.)

LiftPort’s Michael Laine, profiled by Seattle Metropolitan here (one thing space elevators are not short on is publicity), admits that millions–not thousands–of dollars are what he needs to raise to really get the Lunar Space Elevator climbing, but he notes that the test the Kickstarter program funds (a 1.2-mile vertical climb up a cable held aloft by balloons) has Earth-based applications.

Radio frequency communications are all based on ‘line-of-sight’.  Which means the farther you can see, the farther you can communicate (within the limits of sending and receiving power).  That is why cell towers and TV broadcast towers are constructed on hills, mountains and tall buildings.  Every vertical foot matters.  The system we’ve designed can be used for communications in remote villages, to monitor crops for efficient harvesting, early warning for forest fires, perimeter security or to provide wireless internet to a campus.

News, Science

All Powered Up, No Space Elevator Cable to Climb

Space elevator screenshot from Brad Edwards' movie (click through)

This August 11th to 14th, Microsoft played host to the 2011 Space Elevator Conference. The theme for this year was “Developing Stronger, Lighter Tethers–30 MegaYuris or Bust!” (To refresh your memory, one Mega-Yuri = one GPa-cc/g.) On that front, it was “Bust.”

The idea is that by building a 100,000-kilometer carbon nanotube ribbon, with one end on Earth and the other in orbit, we could more easily ship supplies off-world. Depending on the tensile strength of the elevator “cable” in question, it might weigh anywhere between 900 and 50 tons.

Annalee Newitz attended the conference, and summed up the sobering reality:

Every year at the Space Elevator Conference, people bring carbon nanotube fibers and compete to see which can withstand the greatest strain before breaking. Winners stand to gain over a million dollars from NASA in its “strong tether” competition; sadly, this year, nobody had fibers that were strong enough to place…

The upshot is that no one has discovered how to turn nanotube fibers into a non-nano, workable material. Since we need 100,000 kilometers of it, this is a sticking point.

Meanwhile, the power side proceeds by leaps and bounds. Back in 2009, we met up with Kent’s LaserMotive after they won NASA’s power-beaming competition. Even crippled, their climber set a world speed record. Last year, they went on to power a small quadcopter’s flight for over twelve hours, using their combination of high-efficiency photovoltaic cells and near-infrared lasers to transmit energy. (“Invisible extension cords” is how they make “high-powered laser” sound friendlier.)

The AscTec Pelican looks like a toy copter, but it’s not. It’s an Unmanned Aerial Vehicle (UAV), and can carry 500 grams of payload (a camera, for instance). Normally it would stay in flight for 20 minutes.

LaserMotive is now one of ten winners of the 2011 CTSI Defense Energy Challenge (that’s the Department of Defense), out of 220 entrants. Keeping unmanned drones aloft in challenging territory is something the DoD is keen on. (“Do you know how many people have died delivering gasoline?” is how Tom Nugent, LaserMotive president and co-founder, framed a key benefit of laser-beamed power for MSNBC.)

NASA also remains impressed, inviting LaserMotive to their NASA Day on the Hill back in June, even though LaserMotive isn’t a NASA contractor.

It’s hard not to feel like we’re on the cusp of a power revolution, when considering what LaserMotive has accomplished already. When NASA writes: “Using solar power limits the places on Mars that landed rover missions can explore,” you think, But not for long.

Currently, power beaming is limited to about one kilometer, but it’s early days on the frontier. LaserMotive’s Dr. Jordin Kare argues that just as space-based telescopes opened our eyes to what’s really out there, space-based solar collectors that lase energy down would blow our minds on the true potential of solar power, whether those satellites are powering microwaves here or rovers on Mars.

We here at The SunBreak are big boosters of solar power, but we are not crazy. Solar power, for instance, doesn’t work as well at night. (Or, as mentioned, during winter on Mars.) Solar power is affected by the atmosphere–clouds cut down on solar transmission, as many Seattleites have the pallor to prove. Geosynchronous, solar-collector satellites would keep the sun turned on 24/7, then deliver the results wherever needed.

Back here on Earth, present-day, the usefulness of one-kilometer, line-of-sight extension cords is apparent. “Electrical power lines are expensive to install ($20,000 or more per mile for low power residential lines, and $250,000 or more per mile for high-voltage transmission lines),” points out LaserMotive, helpfully. It would be a particularly trenchant irony if wars over oil were the testing ground for a power transmission source that led us to fully harness solar energy.

News, Science

Jordin Kare on His Laser-Powered Lifestyle, Space Elevators, and the Almighty Joystick

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I often think of Seattle as a small town, but maybe it’s only in a city that I would not have known one of my neighbors on the next block was “freelance rocket scientist” Jordin Kare. He’s been living on Capitol Hill since March 2003, though his first visit to Seattle was back in 1979.

Previously at Lawrence Livermore, he moved up from the Bay to consult on a commercial satellite project at Boeing. Now he’s associated with Bellevue’s Intellectual Ventures, though it’s his side project, LaserMotive, that brought him to my attention.

A weary but suddenly richer version of Kare greeted me at the Victrola last week to discuss LaserMotive’s $900,000 win at the Space Elevator Games, held November 2 to 6, 2009.

“So, what can I do for you?” Kare asked. He’s unprepossessing at first glance, clad for Seattle’s cold and rain, unruly gray hair longer on the sides and back, and slightly reserved. After the interview he was off to catch a late show of 2012 with his wife, with whom I had a quick discussion about Joss Whedon’s Buffy, Firefly, and Dollhouse. (She’s still angry at Whedon for the way he killed off “Wash“–really, a shock for all of us Fireflyers.)

This is just proof that you can’t tell by looking at someone that he’s devoted his professional life to laser propulsion; Kare has been a leader in his field pretty much since he got into it as a post-grad in 1986. It is the power-beaming aspect of space elevators that got him into the Games. As it happens, it’s a great, high profile way to demonstrate that you can beam power over a kilometer’s distance in a challenging setting.

LaserMotive was founded, essentially, as a part-time enterprise that would have one product, or goal: to create a laser-powered climber that would win the Space Elevator Games power beaming competition. First prize, for a climber that could travel one kilometer vertically at speeds of five meters per second or more, was $2 million, provided by NASA.

LaserMotive’s climber set a world record, doing the kilometer twice at an average speed of four meters per second (topping out at 4.13 m/s), which netted them $900,00. “Hopefully we’ll pick up the spare next time we go back down there,” said Kare, cheerful at the prospect of holding another huge novelty check, this one for $1.1 million.

 

 

This is not precisely the space elevator you’ve seen on NOVA, with carbon nanotubes. For the competition, pilot Doug Uttecht’s helicopter hauled aloft a 3/16-inch steel cable, 4300 feet long, that weighed about 300 pounds. (The people with this niche expertise are Northwest Helicopters, who also flew the cables in for the Tacoma Narrows Bridge.

There’s another “tether strength” competition that is supposed to yield a ribbon that can stretch from earth to geostationary orbit, which is over 35,000 kilometers. Since there are no 35,000-km extension cords, and onboard-gas-tank technology is already represented in rocketry, beaming the power via lasers is the preferred method.

“Some of the people who are competing are very much believers in the space elevator–Tom Nugent and I, who started the LaserMotive team, are pretty skeptical,” admitted Kare. “It’s one of these things where it’s a lovely idea, and it may be physically possible–which I wouldn’t have said a decade ago–but it’s a very long jump drawing pretty pictures and writing basic equations to being able to build something a hundred-and-some-odd-thousand kilometers long.”

Laser power beaming, in contrast, is “closer and closer to being something you could do practical work with,” said Kare. Satellite solar power arrays, for instance, with 24-hour, unobstructed exposure to the sun, “are enormously more efficient” than ground-based solar power.

“The two problems are always, How much does it cost to get a satellite up there, and how do you get the power back down,” explained Kare. “The laser system that we demonstrated in the climber competition are the first ones that are efficient enough that you could talk about sending the power down on a laser beam.”

Terrestrial power beaming is just now becoming competitive on both the amount of power delivered and cost, in special instances. A laser power beaming system “delivers” about 20 percent of its electrical intake–about 50 percent of the incoming electricity is converted to light, and about 50 percent of that light is converted by photovoltaic sells back to electricity.

“It’s not what you’d call efficient compared to an extension cord across the room,” said Kare, but in remote areas without power infrastructure, it could be cost effective to beam power in. Or, he suggested, electric drones could “refuel” in flight.

These are high-powered laser beams, of course: LaserMotive’s climber is powered by their own infrared 4-kilowatt laser, while its two competitors relied on an 8-kilowatt Trumpf TruDisk 8002. You weld metal with the Trumpf, so safety is not just about not looking into the beam.

“Stepping in front of a high-powered laser beam is generally a bad idea,” confirmed Kare. “Our beams will cook hot dogs very nicely but they will take a few minutes to do it,” he said, adding a second later that this was confirmed in a LaserMotive test. (While LaserMotive has a great safety record, they also have a sense of humor about working lasers–a sign at their Kent workspace reads “1 Days Without Shark-Related Accidents.”)

It meant more work to develop their own laser system, but LaserMotive banked on getting more power from their 4-kilowatt system because the photovoltaic cells that could handle the 8-kilowatt Trumpf’s slightly longer wavelength were simply not as good. The Kansas City Space Pirates, despite having 8,000 watts to burn, could only get around 100 watts out of the standard solar cells they used. LaserMotive’s high-efficiency cells produced more with less area.

(In an ironic development, LaserMotive used a manual joystick to direct the laser beam, while its two competitors went with automated guidance. “Other people had problems with radio interference and computers crashing, we didn’t have any of that, we just had a guy who could cope,” said Kare.)

On their climber’s final run at the competition, a single, missing 1/4-inch titanium nut and Murphy’s Law meant the stripped-down climber appeared slow, baffling the admittedly sleep-deprived LaserMotive crew, who had just lightened it of protective material. A rod missing that nut had jammed into the backstop that would arrest the climber’s descent, and the climber was towing the backstop up. Unaware of the problem, LaserMotive “stepped on it,” transmitting 1,000 watts to the climber, and burnt out a DC-to-DC converter.

“We’re pretty sure we can do the five meters per second next time,” Kare said. The rematch is, tentatively, May 10, 2010.

After that? Possibly exploring power beaming to one of those “remote areas” he mentioned earlier. LaserMotive has been talking to NASA about the prospect of beaming power to robot rovers on the moon or Mars. (The incredibly hardy Mars rovers Spirit and Opportunity have been sleeping through Martian winters, when not enough sunlight arrives to power them.)

Kare, who has worked out not one but two methods of interstellar travel, perked up at this idea. $2-million prizes are one thing. Space exploration, that’s where the excitement is.