An astronaut fixed a torn solar panel on the International Space Station on Saturday in a risky procedure that involved riding a robotic arm to the damaged area in order to install cufflinks on the torn wing, according to the Associated Press.
In an emergency mission, spacewalker Scott Parazynski rode the 90-foot robotic arm to the far end of the shuttle complex as the crew extended the wing to its full length. He then clipped a hinge wire and, guided by fellow spacewalker Douglas Wheelock, installed the cufflinks. The 2.5-foot-long rip had occurred while astronauts were unfurling the new array on Tuesday, but NASA officials weren't sure how the damage was incurred, Reuters said.
The International Space Station is a research facility that is in orbit 240 miles above the Earth's surface. The station uses the solar panels to generate its electricity by capturing sunlight and converting it into power.
Check out this CNET News.com gallery for more photos of the International Space Station and the ripped solar array.
You can make solar panels with impure silicon, claims Roy Johnson. You just have to know how to isolate the undesirables.
CaliSolar, a solar start-up that derives from research originally conducted at UC Berkeley, has come up with a way to make solar cells out of upgraded metallurgical silicon, which is less pure and less costly than the industry standard electrical grade silicon, according to Johnson, the company's CEO, at a meeting at the Dow Jones Alternative Energy Innovations conference taking place this week.
Electrical grade silicon is 99.99999 plus percent pure, but it costs $150 to $250 a kilogram, he said. Even before the worldwide shortage of silicon the stuff costs $50 or more a kilo because of the ornate processing procedures. Only around 70,000 tons are manufactured worldwide.
By contrast, upgraded metallurgical silicon is only 99 percent or so and goes for $20 to $50 a kilo. Approximately 1.2 million tons get made a year.
While the purity differences may not sound big to you, to a solar panel it's usually a deal breaker. Photovoltaic solar panels generate electricity by separating negative charges from positive charges contained in the sunlight that strikes them. The negative charges (electrons) are then captured, converted to AC power, and then used to power things in your house. Pure silicon is usually needed because impurities prevent electron capture.
CaliSolar gets around this by isolating the impurities during manufacturing. The impurities can be channeled into the borders between crystals, Johnson said, which don't generate electricity anyway. The impurities can also be coaxed, through chemical and physical forces, to "float" to the top of a wafer, where they can be etched off. In other words, it nullifies the effect of the impurities by coming up with ways to ensure that the impurities aren't uniformly distributed.
The solar cells coming out of CaliSolar's labs are already roughly competitive with standard silicon solar cells in terms of efficiency, said Johnson, a former networking executive. If CaliSolar can mass manufacture solar cells with a 14 percent efficiency rating--which means that they will convert 14 percent of the sunlight that strikes them into electricity--these solar cells will cost far less than the 16 percent efficiency cells that are common on the market today.
"We are already making market-competitive solar cells" in CaliSolar's labs, he said.
CaliSolar, however, isn't selling its cells yet. It has delivered samples to potential customers and hopes to have a prototype plant built in the first quarter of 2008. Following that, it will build a mass production plant. (To get that bigger plant, however, it will also have to obtain about $30 million to $50 million in funding, which isn't as tough as it sounds these days.) The company conducts its silicon research in Berlin, but will likely build its mass-production solar plant in California, which will likely become the largest solar market in the world, Johnson said.
Silicon panels weigh a lot, so manufacturers want to build them near the customer base. CaliSolar will make silicon ingots, which get turned into wafers, and solar cells, but it does not plan to make solar panels. Instead, it will sell its solar cells to panel makers.
The technique of using impure silicon was invented by Eicke Weber, a former UC professor now at Germany's Frauhofer Institute.
If you can imagine a plane that can stay in flight for years at a time and refuel itself autonomously, then you're thinking like a government agent (or at least a science fiction writer).
Last week, the Defense Advanced Research Projects Agency (DARPA), the research and development arm of the U.S. Department of Defense, began soliciting bids from the private sector to design a plane that can remain aloft for five years with a 99 percent probability.
Called the Vulture Air Vehicle Program, possibly after the vulture's ability to sail on thermal streams, the project "will research and develop technologies and systems which will enable the military to deliver and maintain a 1,000-pound airborne payload for an uninterrupted period exceeding five years," according to a statement from DARPA released May 16.
Vulture's technical challenges include "environmental energy collection, high specific energy storage, extremely efficient propulsion systems, precision robotic refueling, autonomous material transfer, extremely efficient vehicle structural design, and mitigation of environmentally induced loads," according to DARPA.
Translated, the project calls for planes powered from solar or fuel cells, among other options. But DARPA said it's specifically not interested in planes that would use radioactive energy or forms of buoyant flight, i.e., blimps.
The government blog Tech Insider speculated about a few potential contenders, including AeroEnvironment, a Monrovia, Calif.-based maker of electric-powered planes. Scaled Composites, the Mojave, Calif.-based company that's working with Richard Branson on his commercial spaceflight venture, might also be an option given that its owner, aerospace engineer Burt Rutan, designed the Voyager plan that flew around the world without refueling in the '80s.
DARPA didn't specify the mission of Vulture, and a representative wasn't immediately available for comment. But the agency said that it will be accept bids for the project at a Vulture information day in Arlington, Va., on June 7.
"It is envisioned that this program will, at a minimum, develop and demonstrate advanced reliability technologies for air vehicles," DARPA says. "Other advanced technologies may also be developed and demonstrated depending upon the nature of the architectures proposed by offerers."
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