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Boeing-Spectrolab has developed a solar cell that can convert almost 41 percent of the sunlight that strikes it into electricity, the latest step in trying to drop the cost of solar power.

Potentially, the solar cell could bring the cost of solar power down to around $3 a watt, after installation costs and other expenses are factored in, over the life of the panel. The new cost information comes from Boeing, whose Spectrolab unit supplies searchlights and solar simulators, and the Department of Energy, which sponsored the project. Current silicon solar cells provide electricity at about $8 a watt, before government rebates. The goal is to bring it to $1 a watt without rebates or incentives.

The cell achieves 40.7 percent efficiency. The Department of Energy has been sponsoring research to find ways to get solar cells past the so-called 40 percent barrier.

Earlier this year, researchers at Lawrence Berkeley National Laboratories reported that cells made of a new type of semiconductor, zinc-manganese-tellurium, combined with a few atoms of oxygen, could convert around 45 percent of sunlight into electricity. That technology, also partly sponsored by the Department of Energy, has been licensed to RoseStreet Labs in Arizona. It remains to be seen whether this material can be made into solar cells economically.

Sharp Solar, one of the biggest solar companies in the industry, showed a solar cell offering 36 percent efficiency earlier this year. The Sharp cell includes a concentrator–a thin lens that focuses sunlight on the cell–but is not made of silicon. It instead is made out of III-V compounds, molecules made from elements in the III and V columns of the periodic table of elements. (The metallic element gallium–used in semiconductors and optoelectronic devices–is from this neighborhood.)

Currently, the best commercial silicon solar cells can convert 22 percent of the sunlight that hits them into electricity, and physics dictates that maximum efficiency for these cells will come at around 26 percent.

Boeing got around that barrier by integrating two technologies. One, the solar cell, contains a layer of concentrators. From a practical point of view, using a concentrator is like adding extra surface area to the cell.

The solar cell also contains more than one material. Silicon cells interact with only a limited part of the light spectrum. Additional layers of gallium arsenide or other materials can convert light in other portions of the spectrum into electricity. Making so-called multi-junction solar cells is more expensive than making single-junction silicon cells. Still, many companies believe the higher manufacturing expense can be offset by cost savings from the cells’ greater electrical output.

Boeing, however, did not state what materials it used in its cell.

via c|net.

Photographs from NASA’s Mars Global Surveyor may indicate some level of occasional liquid water flow on the surface of Mars.

Though the Mars Global Surveyor may be lost in space, recent comparisons of images captured throughout the satellite’s decade of observing the Red Planet have shown changes in surface geography that, scientists theorize, could be signs of water flow in several locations between 1999 and 2005.

These discrepancies in the presence of light-colored deposits in gullies on Martian craters are "what you would expect to see if the material were carried by flowing water," Michael Malin, of Malin Space Science Systems in San Diego, asserted in a statement from NASA. The findings were announced Wednesday.

Changes in the makeup of gullies on slopes, a topographical feature first noticed by Malin’s research team in 2000, were first noticed after a gully appeared to form after mid-2002. It was, however, attributed to the flow of sand on a dune. But now, comparisons of earlier and more recent images have revealed new light-colored deposits that could possibly be related to ice or salt formations that would come from liquid water flow. Deposits caused by dry dust or sand are more likely to be dark in color.

It’s by no means positive. But Michael Meyer, lead scientist for NASA’s Mars Exploration Program, said that this is "the strongest evidence to date that water still flows occasionally on the surface of Mars."

Ice water and water vapor are known to exist on Mars, but up until this point, there has not been compelling evidence for the presence of liquid water. Due to Mars’ thin atmosphere and subzero temperatures, liquid water–crucial for the sustenance of even the smallest microbial life–could not stay in that form for long. But researchers have suggested that it could be possible for liquid water to escape from underground and stay liquid for long enough to alter surface deposits in the way that the evidence from the Mars Global Surveyor shows.

via c|net.

PASADENA, CALIF. — Two more attempts to regain contact with NASA’s Mars Global Surveyor spacecraft failed this week.

The 10-year-old probe last had radio communication with Earth on Nov. 2, and NASA said earlier this week that the spacecraft’s mission to map the surface of the Red Planet was likely at an end.

But efforts to find out if the orbiting spacecraft was still working continued, including transmitting commands for Mars Global Surveyor to send signals to the NASA rover Opportunity operating on the surface of Mars.

The rover did not detect any signals from MGS during attempts Tuesday and Wednesday, according the Web site for NASA’s Jet Propulsion Laboratory, which manages the mission.

MGS has been the longest and most productive mission to Mars, sending more than 240,000 images back to Earth, according to the space agency.

The spacecraft was launched Nov. 7, 1996, for what was planned as a two-year mapping mission.

© 2006 The Associated Press.

CAPE CANAVERAL, FLA. — Twin spacecraft blasted off Wednesday night on a mission to study huge eruptions from the sun that can damage satellites, disrupt electrical and communications systems on Earth and endanger spacewalking astronauts.

The two spacecraft, known as STEREO, for Solar Terrestrial Relations Observatory, lifted off, stacked one on top of the other, aboard a single Delta II rocket.

The lift off was delayed by several minutes after launch managers became concerned late in the countdown that winds could blow toxic material over nearby Port Canaveral should there be an accidental explosion. However, the area was cleared of people, mainly government workers, permitting the rocket to soar off the launch pad with a roar.

Flight controllers cheered, applauded and gave each other handshakes after the spacecraft separated from the rocket less than a half hour after launch.

Scientists hope the $550 million, two-year mission will help them understand why these eruptions occur, how they form and what path they take.

The eruptions — called solar flares — typically blow a billion tons of the sun’s atmosphere into space at a speed of 1 million mph. The phenomenon is responsible for the Northern Lights, or aurora borealis, the luminous display of lights seen in the upper latitudes of the Northern Hemisphere.

"Of the bazillion stars that we have in our night sky, the sun is the only one that counts," said NASA scientist Madhulika Guhathakurta. "Any understanding or breakthrough we can make in understanding the sun and the sun’s environment is of direct relevance to every human being on this planet."

The two observatories will provide scientists with the first-ever three-dimensional view of the sun by working in tandem, like a set of eyes, in different orbits.

NASA hopes information about the solar flares helps the astronauts who fly to moon and eventually Mars in the coming decades. Astronauts exposed to the eruptions can receive a year’s worth of radiation.

The spacecraft’s launch was delayed several times this year because of technical problems.

Scientists plan to release to the public movies and other images created by the STEREO spacecraft, though viewers may need to use the type of 3-D glasses worn for movies like "Creature From the Black Lagoon."

© 2006 The Associated Press.

Electronically tagging passengers at airports could help the fight against terrorism, scientists have said.

The prototype technology is to be tested at an airport in Hungary, and could, if successful, become a reality "in two years".

The work is being carried out at a new research centre, based at University College London, set up to find technological solutions to crime.

Other projects include scanners for explosives and dirty bomb radiation.

Dr Paul Brennan, an electrical engineer, is leading the tagging project, known as Optag.

He said: "The basic idea is that airports could be fitted with a network of combined panoramic cameras and RFID (radio frequency ID) tag readers, which would monitor the movements of people around the various terminal buildings."

The plan, he said, would be for each passenger to be issued with a tag at check-in.

He said: "In our system, the location can be detected to an accuracy of 1m, and video and tag data could be merged to give a powerful surveillance capability."

more at BBC.