Sunday, March 15, 2009
Nasa ready for launch after repair..After two days of repairs to a faulty hydrogen vent line, mission managers give the go for shuttle Discovery to launch Sunday night.
NASA still doesn't know what caused a hydrogen gas leak that prevented space shuttle Discovery from flying earlier this week.
But officials are hopeful that repairs have solved the problem, and that Discovery will blast off Sunday evening. Good weather is forecast.
Discovery is more than a month late for its scheduled trip to the international space station. First, hydrogen gas valves inside the shuttle had to be double- and triple-checked. Then on Wednesday, hydrogen gas began leaking during fueling where a vent line hooks up to the external fuel tank.
Workers have replaced that hookup and a pair of seals. Nothing obvious was wrong with the removed parts.
Discovery and seven astronauts are set to carry up one last set of solar wings for the space station.
Posted by SANJIDA AFROJ at 5:28 PM
Friday, March 13, 2009
9-second lithium-ion recharge discover Scientists.
Scientists have developed a way to reduce battery charging time from hours to seconds, opening up doors for its use in electronics and electric vehicles.
Scientists Byoungwoo Kang and Gerbrand Ceder of the Massachusetts Institute of Technology found a tunnel shaped lithium compound that speeds up electron transfer within the battery.
The scientists’ lithium-ion battery could mean quick charging for electronics such as laptops and iPods, as well as more efficient hybrid electric vehicles (EV). The faster an EV can recharge its batteries, the more ground it can cover in a given amount of time.
This breakthrough may extend to recharge capabilities of other battery materials. Just as nickel hydroxide achieved fast recharge rates before lithium, other materials may have the potential to follow suit.
Battery recharge speed depends on electron and ion movement. Lithium ions tend to slow down when moving from the battery’s cathode to its electrolyte.
Kang and Ceder found a compound called lithium-iron phosphate, which has a crystal structure that creates a tunnel for lithium to quickly travel through. In order to get the ions to the tunnels, the scientists coated the cathode with lithium-phosphate glass, which allows electron flow. The result: Recharge in nine seconds.
Posted by SANJIDA AFROJ at 9:09 PM
Sunday, March 8, 2009
NASA's planet-hunting telescope, Kepler, rocketed into space Friday night on a historic voyage to track down other Earths in a faraway patch of the Milky Way galaxy.
It's the first mission capable of answering the age-old question: Are other worlds like ours out there?
The spacecraft launches Friday night to embark on the most exhaustive hunt for a potentially habitable planet beyond our solar system.
NASA's Kepler seeks another Earth among the stars.The first spacecraft dedicated to finding potentially habitable planets beyond our solar system is poised to blast off from Cape Canaveral tonight on a three-year mission to probe 150,000 stars in the most sweeping hunt for Earthlike objects ever undertaken by NASA.
The Delta II rocket, carrying the widest-field telescope ever put in space, lifted off the launch pad at Cape Canaveral at 10:49 p.m. Eastern time.
The launch vehicle headed downrange, gathering speed as its three stages ignited, one after the other, passing over the Caribbean island of Antigua and tracking stations in Australia before climbing into orbit.
Kepler will eventually settle down to scan tens of thousands of stars near the constellations Cygnus and Lyra in search of planets where water could exist on the surface in liquid form, a key condition for life as we know it.
"We have a feeling like we're about to set sail across an ocean to discover a new world," said project manager Jim Fanson of the Jet Propulsion Laboratory in La Cañada Flintridge. "It's sort of the same feeling Columbus or Magellan must have had."
The $590-million Kepler mission is jointly managed by JPL and NASA's Ames Research Center in the Bay Area. The spacecraft carries a 15-foot-long telescope with a 55-inch mirror that can scrutinize a wide star field for the telltale dimming of starlight that occurs when a planet crosses in front of it, known as a transit.
Over the last decade, scientists have employed the same technique with ground-based telescopes to discover 340 planets circling other stars. But because the optics of ground-based instruments are compromised by atmospheric interference, most of the planets found so far are Jupiter-like gas giants that orbit so close to their parent stars that any life forms would be incinerated.
The scientists expect to find hundreds of planets during the mission, scheduled to last more than three years. But even with the telescope's wide field of vision, it will be no easy task for Kepler to find smaller, Earth-like planets. Scientists have calculated that the change in brightness caused by such a planet transiting its star will be only about 0.008%, or about 84 parts per million. On top of that, there is less than one chance in 100 that a planet circling a far-off star will be aligned in just the right way for Kepler to spot a transit.
A final complication is that not all dimming is caused by transits. Sunspots on the surface of a star are cooler areas linked to an increase in magnetic activity. They also cause the star's light to dim. But Kepler scientists said they think they understand the signature of sunspots well enough to deal with that problem.
For a planet to become a candidate for the first Earth-type planet around another star, Kepler must measure at least three separate transits, scientists said. If the team is uncertain about some measurements, or simply wants more observing time, the mission could be extended to six years, NASA said.
Posted by SANJIDA AFROJ at 10:12 AM