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Arctic
ice set to match all-time record low Space debris has reached ‘tipping point’ Prof Yash
Pal THIS UNIVERSE
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Arctic ice set to match all-time record low The area of the Arctic that is covered by floating sea ice at the end of this summer’s period of melting is likely to match the all-time record low of 2007, scientists said yesterday.
Some researchers believe that the actual volume of sea ice in the Arctic has already fallen to a record minimum this summer. The extent of the Arctic covered by sea ice this summer has also continued to decline — a trend seen since 1979 when the first satellite measurements were collected. Although satellites are good at measuring the surface area of ocean that is covered by the floating sea ice, it is not so easy to assess ice volume, which requires accurate measurements of ice thickness over wide regions. Satellites have produced clear evidence that the sea-ice extent — the area covered by at least 15 per cent of ice — has fallen consistently and significantly each summer over the past 30 years. Since 1979, sea ice extent in summer has fallen by around 30 per cent, according to satellite data. Walt Meier, of the US National Snow and Ice Data Centre in Boulder, Colorado, said that at the moment the Arctic sea ice is on track to be second or third lowest in terms of sea-ice extent, although there is still about another week or so until the summer melt period finally comes to an end. “A lot still depends on the weather. If a warm front comes through, there could still be some rapid melting. But at present we think it could be close to or as low as the 2007 record minimum,” Dr Meier said. The sea ice in the Arctic goes through annual cycles of melting in summer and reforming each winter. However, as average temperatures in the the Arctic region have increased in recent decades — faster than in most other regions of the world — summer sea ice has disappeared faster than predicted, and winter ice has not reformed as readily as it once did. In 2007, there was a “perfect storm” of driving winds that piled the sea ice up against the Greenland coastline and high pressure that removed cloud cover at the height of summer season to create idea conditions for the melting of the sea ice. This year the sea ice is more dispersed, but in terms of total surface area covered by ice, it probably ranks close or equal to 2007, Dr Meier said. The last four summers have experienced the four lowest minima since satellite readings were first gathered and eight of the ten lowest summers have occurred in the past decade, he said. At the same time, there has been a marked decrease in thick “multi-year” sea ice that is older than five years, and an increase in the proportion of thinner, younger ice which is more likely to melt away completely in summer. Scientists at the University of Washington in Seattle estimated that the actual volume of sea in the Arctic is already at an all-time low, lower even than in 2007 because then the ice that was left was older, multi-year ice several metres thick. However, estimating ice volume is notoriously difficult. |
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Space debris has reached ‘tipping point’ Space junk has made such a mess of Earth’s orbit that experts say we may need to finally think about cleaning it up. That may mean vacuuming up debris with weird space technology — cosmic versions of nets, magnets and giant umbrellas, according to the chairman of an expert panel that issued a new report on the problem. There are 22,000 objects in orbit that are big enough for officials on the ground to track and countless more smaller ones that could do damage to human-carrying spaceships and valuable satellites. The International Space Station has to move out of the way of debris from time to time. “We’ve lost control of the environment,” said retired Nasa senior scientist Donald Kessler, who headed the National Academy of Sciences report. Since the space age began 54 years ago, civilisation has littered the area just above Earth’s atmosphere with leftover boosters and other parts that come off during launches, as well as old satellites. When scientists noticed that this could be a problem, they came up with agreements to limit new space junk and those plans had been working. Those agreements are intended to make sure what is sent into orbit eventually falls back to Earth and burns up. But two events in the past four years — a 2007 Chinese anti-satellite weapon test and a 2009 crash-in-orbit of two satellites — put so much new junk in space that everything changed, the report said. The widely criticised Chinese test used a missile to smash an aging weather satellite into 150,000 pieces of debris larger 1cm and 3,118 pieces can be tracked by radar on the ground, the report said. “Those two single events doubled the amount of fragments in Earth orbit and completely wiped out what we had done in the last 25 years,” Mr Kessler said. All that junk that means something has to be done, “which means you have to look at cleaning space”, he said. The study only briefly mentions the clean-up possibility, raising technical, legal and diplomatic hurdles. But it refers to a report earlier this year by a US Defence Department science think-tank that outlines all sorts of unusual techniques. The report by the Defence Advanced Research Projects Agency is called “Catcher’s Mitt” and it mentions harpoons, nets, tethers, magnets and even a giant dish or umbrella-shaped device that would sweep up tiny pieces of debris. While the new report does not recommend using the technology, Mr Kessler said it is needed. He likes one company’s idea of a satellite that is armed with nets that could be sprung on wayward junk. Attached to the net is an electromagnetic tether that could either pull the junk down to a point where it would burn up harmlessly or boost it to safer orbit. Nasa officials said they are examining the study. The report is from the National Research Council, a branch of the National Academy of Sciences, which is an independent organization chartered by Congress to advise the US government on science.
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THIS UNIVERSE It is extremely difficult for a cockroach to get back on his feet when it is turned upside down. But when we spray insecticide on it, instead of running, it always turns upside down before dying. Why? I am sure I do not know the exact answer to your question. But let me attempt something. I do not know what is exactly the cause of death of a cockroach when we spray insecticide on it. I wonder if some intelligent autopsies have been done on dead cockroaches. Deadly concoctions we intelligent and powerful humans have designed to do get rid of cockroaches must include some thing that disables a part of their system that behaves like the central nervous system. This means that they probably lose control of their limbs very early on their way to death. They probably try but are unable to run away and just topple on there back. When drops fall from a tap, why they are ‘circular’ in shape? Not only drops falling from a tap but even all raindrops are spherical in shape (in your words, circular). The reason for this lies in the fact that when we have a small bit of water, it has to have a surface surrounding it in all directions. Surfaces of liquids, like water, are held together because all the molecules are attracted inwards, towards other molecules. This gives the surface a property like that of a stretched membrane. Stretched membranes want to be as small as possible. Because of this, a small quantity of water acquires a spherical shape. Readers wanting to ask Prof Yash Pal a question can e-mail him at palyash.pal@gmail.com
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NASA spacecraft to probe the inside of the moon CAPE CANAVERAL, Florida: More than 100 spacecraft have been to the moon, including six with U.S. astronauts, but one key piece of information about Earth’s natural satellite is still missing-what’s inside. Learning about the interior of the moon is the primary goal of a new NASA mission called Gravity Recovery and Interior Laboratory, or GRAIL. Young, nearby supernova dazzles scientists LOS ANGELES:
California astronomers have found the closest, brightest supernova of its kind in 25 years, catching the glimmer of a tiny self-destructing star a mere 21 million light years from Earth and soon visible to amateur skywatchers. The discovery, announced on Wednesday, was made in what was believed to be the first hours of the rare cosmic explosion using a special telescope at the Palomar Observatory near San Diego and powerful supercomputers at a government laboratory in Berkeley.
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