Comment Re:makes sense (Score 1) 103
The key is not mass density, but unit of energy per weight. Turns out you and put more energy though fiber optic then copper for a given weight of material.
Comment Re:Old idea, commercially available now (Score 3, Informative) 103
Yup totally serious. Not plan old comm fiber optic, but consider how a laser welding machine pumps kilowatts though a correctly spec'ed fiber optic cable.
Comment Re:How is this better than a balloon? (Score 2) 103
Balloons get really big fast as you add payload. This means that more and more of your energy is used for station keeping rather then payload. Also with the UAV solution it is small and light enough to say fit in the trunk of a car and be handled by one person. For a balloon to carry any practical payload it is large enough where one person can no longer handle it on there own.
Comment Re:Old idea, commercially available now (Score 1, Informative) 103
Main advantage of fiberoptic is two fold, first it is lighter then copper per unit of energy you can push through it. Second it is has no electrical resistance, so you don't get a huge voltage drop over long distances. What this means is you can have more payload at greater height then with a copper based electrical solution.
Submission + - UAV hoisted tower powered by laser over fiberoptic (techbriefs.com)
carstene writes: LaserMotive, winners of the 2009 NASA power beaming contest, has a new invention , a virtual comm or surveillance tower. It's a quadcotper that can run indefinitely, powered by laser beam over a fiber optic cable. This allows the "tower" to reach great heights and avoids most laser safety issues.
Comment Not new for caps. (Score 1) 182
Cooper Bussman has made aerogel supercaps for years. You can get values up to like 100F that will fit in your hand and only weigh grams. Very cool but only 3v max so the uses are limited.
Comment Memristors availably (Score 1) 320
When I can buy one at mouser/digikey then maybe I'd believe you can build something neat with them in 5 years.
Submission + - Lasermotive powers quadcopter in flight for 12 hrs (lasermotive.com)
carstene writes: Lasermotive, winner of the 2009 NASA Centennial Power Beaming / Space elevator games, has demonstrated powering a quadcopter with a laser beam for 12 hours without landing. This is the longest flight of an electric rotorcraft to date. There is a video on youtube.
Mars Images Reveal Evidence of Ancient Lakes 128
Matt_dk writes "Spectacular satellite images suggest that Mars was warm enough to sustain lakes three billion years ago, a period that was previously thought to be too cold and arid to sustain water on the surface, according to research published today in the journal Geology. Earlier research had suggested that Mars had a warm and wet early history but that between 4 billion and 3.8 billion years ago, before the Hesperian Epoch, the planet lost most of its atmosphere and became cold and dry. In the new study, the researchers analysed detailed images from NASA’s Mars Reconnaissance Orbiter, which is currently circling the red planet, and concluded that there were later episodes where Mars experienced warm and wet periods."
Submission + - NASA Power Beaming challenge is on for November 2
carstene writes: The NASA Centennial Challenge Powered Beaming competition, to develop technology for uses such as a space elevator, or to power a rover in a shadowed creator on the moon, was delayed indefinitely due to trouble setting up the kilometer high race track. It has now had the kinks worked out and is rescheduled for the week of November 2nd. The competition involves using a high power laser to beam power to a robot that climbs a kilometer high cable attached to a helicopter. You can follow the competition at the organizers blog. I'm a member of Lasermotive team, one of the 3 competing. The competition was previously covered on slashdot.
Comment Kurt Vonnegut (Score 1) 1021
Cat's_Cradle is a great, easy to read, endlessly discussable sci-fi book by a master.
Comment Re:Sterling Engine (Score 1) 98
A diode laser, like we are using is also about 50% efficient in turning electrons into photons, so under ideal conditions you get around 25% of the electricity out the other end that you put in. I will point out that you still have to heat the Stirling engine with something like a laser so it has exactly the same lose on that end as beaming to a PV does.
Comment Re:Microwave instead of visible energy (Score 3, Informative) 98
Turns out that divergence is set by the wavelength, larger the wavelength the bigger the minimal divergence. Check out http://en.wikipedia.org/wiki/Diffraction-limited_system . Our lasers wavelength is 808 nanometers. Compare that to say 1 centimeter for microwave and you can see that microwaves will always require a much bigger "lens/mirror" to focus them.
Comment Re:Microwave instead of visible energy (Score 1) 98
Beam divergence is the biggest reason I'm aware of. Another sizable reason is kilowatt for kilowatt an infrared laser is a lot cheaper. Diode lasers (especially infrared ones) have collapsed in price in the last few years.
Comment Re:Sterling Engine (Score 3, Informative) 98
While the efficiency of a heat engine is great, the power to weight ratio is awful. So much in fact that it is really hard to build one that can lift itself.
A laser that is matched to the bad gap of a pv cell can be over 50% efficient. So it is not too bad on that front and a lot less weight then a heat engine.
By the way, a Sterling Engine is an engine made of silver, a Stirling Engine is a heat engine.
