发表主题回复主题
1/20‹‹1››

its track can be more precisely

xiaohuahua

UID:541

只看楼主   ¦        #1
  • 等级:5级
  • 昵称:
  • 组别:中级会员
  • 积分:832
  • 金币:411

Chinas Manchester City defender Sun Jihai(C) rests during a training session as Chinas international team are preparing for the coming Asian  Cup soccer tournament in July, 2007.
Aaron Hernandez Youth Jersey
. [Xinhua] 123  
Victor Cruz Jersey
. Its an ambitious goal. But its possible with the rapidly growing momentum, ?Pani told Xinhua in an exclusive interview. Bilateral trade between India and China has seen a drastic jump over the last decade. From a modest $3 billion at the turn of the century, annual trade reached $42 billion in 2008-09, Indias Minister of State for Commerce and Industries, Jyotiraditya Scindia, said.
Womens Jason Pierre-Paul Jersey
. - Foul trouble limited Kevin Durant for much of three quarters, but it didnt stop him when the Oklahoma City Thunder needed him most.
Patrick Chung Jersey
.J. -- According to the Philadelphia Daily News, Flyers general manager Paul Holmgren confirmed Saturday afternoon that 34-year-old goalie John Grahame has signed a professional tryout contract with the teams American Hockey League affiliate in Adirondack.
BenJarvus Green-Ellis Womens Jersey
. Lailier a également voilé la vue du gardien adverse lorsque Martin St-Louis a créé légalité avec seulement 8,7 secondes à faire à la troisième période. Gagné a raté 18 matchs en raison dune blessure au cou. Son but gagnant a été inscrit lors dune descente à deux contre un avec Brett Clark et il sagissait de son premier but dans luniforme du Lightning.
Red Eli Manning Jersey
. The Bruins entered Thursdays action tied with Montreal atop the Northeast Division. However, Boston grabbed a two-point lead over the Habs last night when the Bruins picked up a road win over the Islanders and the Canadiens lost in regulation at Edmonton. WASHINGTON — A blue-ribbon panel of scientists is trying to determine the best way to detect and ward off any wandering space rocks that might be on a collision course with Earth. ``Were looking for the killer asteroid, James Heasley , of the University of Hawaiis Institute for Astronomy , last week told the committee that the National Academy of Sciences created at Congress request. Congress asked the academy to conduct the study after astronomers were unable to eliminate an extremely slight chance that an asteroid called Apophis will slam into Earth with devastating effect in 2036. Apophis was discovered in 2004 about 17 million miles from Earth on a course that would overlap our planets orbit in 2029 and return seven years later. Observers said that the asteroid — a massive boulder left over from the birth of the solar system — is about 1,000 feet wide and weighs at least 50 million tons. After further observations, astronomers reported that the asteroid would skim by Earth harmlessly in 2029, but it has a one in 44,000 probability of slamming into our planet on Easter Sunday , April 13, 2036 . Small changes in Apophis path that could make the difference between a hit or a miss are possible, according to Jon Giorgini , a planetary analyst in NASAs Jet Propulsion Laboratory in Pasadena, Calif. ``We have not eliminated the threat in 2036, Lindley Johnson , the manager of NASAs asteroid detection program, told the committee. The academy panel is headed by Irwin Shapiro , a former director of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass. It has a two-part assignment from Congress : Detect and deflect asteroids that might hit earth. First, the Shapiro committee is supposed to propose the best way to detect and analyze 90 percent of the so-called ``near Earth objects orbiting between Mars and Venus that are wider than 460 feet by 2020. About 20 percent of these are identified as potentially hazardous objects because they might pass within 5 million miles of Earth (20 times the distance to the Moon). More than 5,000 near Earth objects, including 789 potentially hazardous objects, have been identified so far. Johnson predicted that future surveys will find at least 66,000 near Earth objects and 18,000 potentially hazardous objects. A collision with one or more of these many objects littering the solar system is inevitable, Johnson said. ``Once every hundred years there might be something to worry about, but it could happen tomorrow. For example, astronomers had only 24 hours notice of a small asteroid that blew up over nortthern Africa on Oct.
Hakeem Nicks Authentic Jersey. 7 . A larger, more dangerous object presumably would be spotted years or decades ahead, giving humans time to change its course before it hit. The Shapiro panels second task is to review various methods that have been proposed to deflect or destroy an incoming asteroid and recommend the best options. They include a nuclear bomb, conventional explosives or a spacecraft that would push or pull the asteroid off its course. Offbeat ideas are painting the surface of the asteroid so that the suns rays would heat it differently and alter its direction, and a ``gravity tractor, a satellite that would fly close to the asteroid, gently nudging it aside. The earlier that a dangerous asteroid is found, and the farther it is from Earth, the easier it will be to change its trajectory, panel members were told. A relatively small force would be enough while the object is millions of miles away. The year 2029 could be crucial. When Apophis makes its first pass by Earth, its track can be more precisely determined. That will enable astronomers to judge whether Earth will escape with a near miss or will have to take swift action to avoid a blow that could devastate a region as large as Europe or the Eastern United States . To deflect an asteroid, scientists need to know its shape, weight and composition. A ball of loose rubble would be handled differently from a solid metallic rock. ``Finding them is one thing, but you have to know your enemy, said James Green , the director of NASAs Planetary Science Division. So far, NASA has spent $41 million on asteroid detection and deflection, but the Near Earth Object Program is running out of money. ``Its just barely hanging on, Shapiro said. Two expensive telescopes to focus on dangerous asteroids have been proposed, but Congress and the incoming Obama administration must be persuaded to approve the money. ``Without new telescopes, wed never get to 90 percent (detection), Johnson said. After a lot of original skepticism, Congress now looks favorably on the asteroid project, according to Richard Obermann , the staff director of the House Subcommittee on Space and Aeronautics. ``There used to be a high giggle factor among members, Obermann said. ``But its now a very respectable area of investigation. Johnson told the Shapiro committee that the search for killer asteroids must have a high priority. ``The space program could provide humanity few greater legacies than to know the time and place of any cosmic destruction to allow ample time to prepare our response to that inevitable event, he said. ' ' '
Time: 12-01-31 16:41

 
›› 举报 ¦ 奖励 ¦ 引用 ¦  TOP   
发表主题回复主题
1/20‹‹1››