(SAT必威体育精装版时事类素材收集.docVIP

SAT必威体育精装版时事类素材收集 　　一. 马航事件(创新科技类话题) 　　We can see countless millions of miles into the blackness of space, but a 3-mile depth in the ocean is testing the very limits of our technology because most of it just doesn’t work underwater. 　　As the hunt for Malaysia Airlines Flight 370 demonstrates, at that depth — minuscule compared with the vastness of space — everything is a virtual unknown. A high-tech unmanned underwater submarine, Bluefin-21, has been dispatched four times to look for wreckage from the jet, but the crushing water pressure and impenetrability of this void mean that only its most recent pair of missions were completed. Scrutinizing dust and rock particles on the Red Planet, tens of millions of miles away, is a breeze. Understanding what’s on the seafloor of our own planet is not. 　　About 95% of deep ocean floor remains unmapped, but that’s almost certainly where the most sought after aircraft in history is going to be found. “Our knowledge of the detailed ocean floor is very, very sparse,” Erik van Sebille, an oceanographer at the University of New South Wales in Sydney, tells TIME. 　　The reason for our ignorance is simple. Virtually all modern communications technology — be it light, radio, X-rays, wi-fi — is a form of electromagnetic radiation, which seawater just loves to suck up. “The only thing that does travel [underwater] is sound,” says van Sebille, “and that’s why we have to use sonar.” 　　Sound is formed by mechanical waves and so can penetrate denser mediums like liquids: but at a 3-mile (5 km) depth, even sonar starts to have problems establishing basic parameters. The waters in which the search for MH 370 is happening, for example, were thought to be between 13,800 and 14,400 ft. (4,200 and 4,400 m) deep, because that’s what it said on the charts that had been drawn up over time by passing ships with sonar capabilities. It turns out those seas are at least 14,800 ft. (4,500 m) deep. We only know that now because that’s the depth at which Bluefin