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2018年01月16日 15:35:08来源:中国对话

A geostationary satellite orbitsthe planet at the same rate asthe planet rotates, so the satellite is always over the same patchof ground.同步卫星以行星旋转的速度绕着行星运动,所以卫星总是处在地面同一块地方的上空。Cool! you say. Id like to have one of those about twenty feet over my house.你会说,好酷!我宁愿有一个离我们房子只有二十英尺的卫星。Sadly, geos onlywork easily at one distance:不幸地,同步卫星只能在同一个高度工作,22,500 miles up.Why is that?22,500 米的高空。为什么?Other satellites can have different orbits, cant they?其他卫星有不同的轨道,他们有吗?Yes, they can. But thats because they can also move at different speeds.是的,他们有。那是因为他们能以不同的速度运动,A geo doesnt have thatoption-by definition it must orbit at the same speed as the earth turns.而同步卫星没有那样的选择 他必须与地球自转同速运动。And that speeddetermines how high up it must be!运动速度决定了他必须在的高度。A satellite has to move at a certain speed to balance out gravity; otherwise it wont stay in orbit.卫星必须以某一确定速度运动来平衡我们的重力;否则将不能保持在同一轨道上。Now, a geo must move at the speed the earth turns.现在,同步卫星必须以地球自转的速度同速运动。If you put it in a very low altitude, that speed wouldnt be enough to balance gravity.如果处于很低的高度,卫星的速度将不足以平衡重力。Go higher, though, and gravity gets weaker.高度越高,重力越小。At 22,500 miles, gravity will be just weak enough sothat a satellite moving at the speed of the earths rotation will stay in orbit without help.在22,500的高空,重力小到可以使卫星在没有帮助的情况下与地球同速运动,并且始终在同一轨道上。Of course, if you wanted to have a geo at a different altitude, you could always attach rockets toit and have them push continuously.当然,如果你想有一个在不同高度的同步卫星,可以把卫星附在火箭,让火箭不断推动卫星前进。But thats a pretty expensive option. At 22,500 miles,nothing else is required.但是,这是相当昂贵的选择。在22500的高空,其他什么东西都不需要。201411/340145。

  • The lawyer for a suburban Minnesota police officer who killed a black driver during a traffic stop last week says the officer was reacting to Philando Castiles gun, not his race. The attorney did not elaborate on how Castile presented the weapon or what led up to the fatal traffic stop and shooting. The Castiles fiance took of the aftermath of his shooting has Concealed Pistol License (CPL) holders asking themselves: What are the dos and donts if you are stopped by police?Rick Ector is the owner and operator of Ricks Firearm Academy and offers CPL classes, womens classes and instructor classes in Metro Detroit. Ector joins Stateside to give advice on what to do if youre a CPL holder and you get pulled over in Michigan.Listen to the full interview above.GUESTRick Ector is owner and operator of Ricks Firearm Academy.201607/454263。
  • Increased public and political pressure has led Enbridge to invest million in equipment to protect against a spill from the 63-year-old pipeline under the Straits of Mackinac. The Canadian energy company hopes to bring safety reassurance to Michigan through a series of community open houses near Line 5.Though Line 5 receives regular supervision by Enbridge, Stephen Lloyd, a senior manager of emergency response for the company, said an investment of million is being put into emergency response equipment.;Were looking to make sure that were able to contain and recover (oil) in open water,; Lloyd said on Stateside. ;To prevent it (from) actually making landfall.;Lloyd added that the new technology, which includes skimmers for icy conditions, will make sure Enbridge is ;prepared in the unlikely event of a release.;Line 5 carries more than 500,000 barrels of crude oil and natural gas liquids every day under the Straits, and has been operating since 1953. But Lloyd says the public should not be concerned about the age of the pipeline.;With proper maintenance programs and rigorous monitoring,; Lloyd said, ;the life expectancy can be indefinite.;But that maintenance may not be enough, said Michigan Radios Mark Brush, who has been covering Enbridge and Line 5 for several years.Brush told Stateside most people just arent comfortable having an oil pipeline run through Lake Michigan.Brush noted that Enbridge is exceeding the governments standards for pipeline safety, but the National Wildlife Federation doesnt believe those standards are tough enough. Ever since the spill of Line 6B in Kalamazoo in 2010, Line 5 has been under a watchful eye.;People were shocked to find out theres something under Lake Michigan,; Brush said, adding that this pressure led to the U.S. Senate passing tighter pipeline regulation.Lloyd joined Cynthia Canty on Stateside to talk about Enbridges safety plan. Michigan Radios Mark Brush also joined Stateside to discuss the concerns surrounding Line 5.In full disclosure, Enbridge is a financial supporter of Michigan Radio.GUESTSStephen Lloyd is a senior manager of emergency response with Enbridge.Mark Brush has covered Enbridge and Line 5 for Michigan Radio201606/450541。
  • If you turn on any of the cable news channels, the odds are you will soon see a studio full of Republican analysts wringing their hands and discussing whether Donald Trump can be stopped. The answer, as the candidates convene on Michigan, is very likely not.Nobody I know really thinks Trump will lose the Michigan primary in five days, though the conventional, or establishment Republicans are talking about holding down his margin.Their last real hope of stopping him comes in twelve days. Beginning on March 15, most GOP state primaries switch to a winner-take-all system, rather than dividing delegates proportionally.They hope that Marco Rubio can win his home state of Florida and John Kasich his Ohio, denying Trump any delegates from those two big states, and hopefully preventing him from getting to the convention in Cleveland with a first ballot majority.Well, thats mathematically possible. But anytime you have a candidate who wins landslide primary victories in both Massachusetts and Alabama on the same night, you have a national phenomenon. There is also no candidate who offers countervailing universal appeal. But what many Republicans really fear, however, is not Trumps policies.They worry he will be defeated in a terrible landslide that will take hundreds of other Republicans in Congress and state legislatures with him. And that may be a legitimate fear. In fact, it happened before, with particularly devastating consequences for Republicans in Michigan. The year was 1964, and Arizona Senator Barry Goldwater was moving towards the Republican Presidential nomination.Goldwater was not as crassly vulgar as Trump. That was not an age when candidates made fun of their opponents appearances or had to be bleeped. But in other ways, the resemblance is uncannily familiar. Goldwater had policies that frightened people.He talked about selling off the Tennessee Valley Authority and making Social Security voluntary, something oddly echoed by Trumps proposal to replace Medicaid with block grants to the states. Trump talks about bombing ISIS into oblivion; Goldwater joked about lobbing a nuclear missile into the mens room at the Kremlin.Goldwater opposed the landmark Civil Rights Bill of 1964, saying it infringed personal freedoms. National Republican leaders reacted to all of that exactly as they are now. But all efforts to stop him were futile.Back then, Michigan governors still had to run every two years. George Romney, running for a second term, angered conservatives by refusing to endorse Goldwater. It was a smart move. Goldwater became the only presidential candidate in history to lose Michigan by more than a million votes. But more than 700,000 people split their tickets to reelect Romney.But otherwise, Michigan Republicans were devastated. They lost five seats in Congress. Democrats won enormous majorities in both houses of the legislature. Nationally, the picture was pretty much the same.Barry Goldwater lost by sixteen million votes. Democrats ended up with more than twice as many seats as Republicans in both houses of Congress, meaning President Lyndon Johnson could get pretty much anything he wanted, which is how Medicare and Medicaid and Head Start and many other programs came to be born. Republicans soon began to recover.But that election was a traumatic experience for the GOP. This year, there is increasing fear they may be about to repeat it.Jack Lessenberry is Michigan Radios political analyst. Views expressed in his essays are his own and do not necessarily reflect those of Michigan Radio, its management or the station licensee, The University of Michigan.201603/429475。
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