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LaserMotive Finds Success In Space Elevator Competition
Bucc5062 writes "LaserMotive has achieved the first step towards the creation of a working space elevator by qualifying for the $900,000 prize in a contest sponsored by NASA. To achieve this first level, LaserMotive needed to propel a platform up a cable dangling from a helicopter at over 2 m/s. They hit a top speed of 4.13 m/s. The next level of qualification will be to achieve a climb speed greater then 5 m/s. LaserMotive beamed roughly 400 watts of laser power to a moving target at a distance of 1 kilometer, as part of the vertical laser alignment procedure. The target was a retro-reflective board a little larger than 1 meter on a side. The contest will continue for another two days with at least two other teams challenging for the prize. To win the Power Beaming competition, the LaserMotive system uses a high-power laser array to shine ultra-intense infrared light onto high-efficiency solar cells, converting the light into electric power which then drives a motor. 'Our system will track the vehicle as it climbs, compensating for motion due to wind and other changes. Building on our experience from last year’s competition, we are designing an improved system able to capture the full $2,000,000 prize.'"
I thought these guys had it pegged?
Of course, producing enough of the stuff and making the belt out of it is still non-trivial...
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Outside of the fact that we can't effectively design the cable, how high would the cable be placed out in to space?
The counterweight has to be beyond geostationary orbit. So at least 25k miles. Plus the whole assembly will be dragged along by the part connected to Earth so it's not going straight out to geostationary. I've heard something like 60k miles.
Actually, this company isn't developing propulsion. Propulsion is an electric motor. This company is demonstrating energy transmission. LaserMotive is even skeptical about the concept of a space elevator, but participated because they wanted prize money to fund further development of energy transmission for more, shall we say, earthly profitable pursuits.
Long before this could be used for an elevator (due to the lack of "baloneyum" as someone else put it), this technology will probably be perfected and in use for getting power to areas where cables aren't practical, and even under very controlled circumstances maybe even beaming power down from orbit or other interesting applications that have been talked about since the 60s or earlier.
Plus, frikkin' satellites, with frikkin' death ray laser beams!
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LaserMotive's two principals, Jordin Kare and Thomas Nugent, said they were relieved after two years of work. They said their real goal is to develop a business based on the idea of beaming power, not the futuristic idea of accessing space via an elevator climbing a cable.
Well, I'm not a scientist but several obvious ones come to mind.
For starters, you are going to have resistance greater than air through all but superconductive materials. Second, you're going to have trouble grounding it unless you have two cables, then you're going to need to keep the cables separated or shield them which means two discrete materials. Third, you'll have the issue of voltage surges through (as you've stated in your post) lightning strikes, static electricity, etc - very bad for electric motors.
Plus, they haven't sorted the cable part yet. The power problem is trivial compared to the cable, so the ideal here would be to free the cable designers of as many requirements as possible. "Strong enough to hold a crapload of miles of its own weight PLUS a payload and manage the various issues like wind, long-term exposure to UV/sunlight, rain, errant airliners, and vacuum long-term" is already a tall order beyond our technological limits by a pretty ridiculous margin at the moment. It's probably best not to limit the possible solutions to "also has to be a superconductor with separately superconducting ground line" if we can solve the power problem another way and just let the cable geniuses focus on the "supports its own weight, etc" problem.
Maybe someone will come up with a shielded carbon nanotube superconductor that also happens to be incredibly strong.
At that point, all this time spent on power transmission still has other applications anyway, so it's not really wasted.
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You seem to be rather ignorant of the idea, and all of your concerns are addressed directly in Edwards' book, The Space Elevator.
A single climber on a single cable is the first step, as it is most cost effective to launch. Once it is up, the first priority is widening the ribbon, and producing more ribbons. Once they are in place, loss of any single ribbon would be not be very significant, as the ribbon itself is cheap, and deploying it is now cheap.
Next, the goal was always to run multiple climbers up the ribbon, in a single direction, as that makes best use of the ribbons capacity. For climbers spaced along the ribbon, the force of gravity is greatly reduced the further up you go, so you can fit considerably more on the ribbon as compared to a single heavy climber. Still, you have the option of clearing the ribbon and sending up very heavy items, it would just cost more.
Anything else you can think of has also likely been addressed in that book, from technology to economics.
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