首页
外语
计算机
考研
公务员
职业资格
财经
工程
司法
医学
专升本
自考
实用职业技能
登录
外语
Watch out for Falling Satellites What Is Happening? An out-of-control US spy satellite will crash to Earth in the coming
Watch out for Falling Satellites What Is Happening? An out-of-control US spy satellite will crash to Earth in the coming
admin
2013-06-17
34
问题
Watch out for Falling Satellites
What Is Happening?
An out-of-control US spy satellite will crash to Earth in the coming months, government officials say. The satellite is large enough that debris are likely to survive atmospheric re-entry and strike the Earth, sometime in late February or early March, says Gordon Johndroe, a spokesman for the National Security Council.
Is That Normal?
"This is relatively routine in that satellites deorbit all the time," says Johndroe. Pieces of uncontrolled debris heavier than two stones — mostly discarded rocket stages — crash to Earth as often as once every three weeks, says Jonathan McDowell, an astronomer and launch observer at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts. Many discarded pieces retain some power, so that controllers on Earth can guide them to a point far from human habitation, usually using a final dive into an ocean.
In 2001, Russian space officials broke up the old Mir space station in this way over the South Pacific. That’s not the case for this US one, however.
"Obviously, we want to take a look at the potential for it to land in a populated area," says Johndroe. "As background, I’d like to say that over the past 30 plus years, there have been many satellites and other man-made objects falling from space — of course, they falling with very little damage and no injuries. What makes this case a little bit different, however, and in particular for the president in his consideration, was the likelihood that the satellite, upon descent to the Earth’s surface, could release much of its thousand-plus pounds of hydrazine fuel as a toxic gas. "
What Are the Chances of It Crashing Through My Roof?
Exceedingly slim, says McDowell. Remember that some 70% of the Earth is water, and most lands are void of people. "There is no reason for people to get alarmed about it," he says. According to the NASA Orbital Debris Program Office, there have been no confirmed instances of serious property damage or injury caused by crashing debris in 40 years. The likelihood of the satellite falling in a populated area is small, and the extent and duration of toxic hydrazine in the atmosphere would be quite limited; nevertheless, if the satellite did fall in a populated area, there was a possibility of death or injury to human beings beyond that associated with the fall of satellites and other space objects normally, if we can use that word. Specifically, there was enough of a risk for the president to be quite concerned about human life, and on that basis, he asks us to review our options.
What Is This Satellite?
Since it is a spy satellite, this isn’t public information. But it is likely to be USA 193, which, according to news reports, was launched at the end of 2006 for the National Reconnaissance Office (NRO) and which was lost to ground-based controllers upon reaching orbit. At the time, amateur sky watchers noticed that its orbit was slightly off and wasn’t being corrected. Based on the slight losses in altitude, they had predicted an eventual crash this spring, McDowell says.
If the dying satellite is indeed USA 193, its specifications can be better defined. USA 193 was launched on a Boeing Delta 2 rocket, which limits the size of the satellite to between two and four tonnes and five or six meters in length — about the size of a minivan, McDowell says. This satellite is now at an altitude of 250 kilometers and is falling a kilometer per day. It orbits in the mid-latitudes, between 58 degrees north and south. Where it will fall within that range is impossible to know now, so McDowell says the chance of landing in the United States, for example, is 2%, based on area. Better estimates should be available a day before landing.
Is the "Minivan-sized" Satellite a Big One?
Nowhere near as big as a satellite that fell uncontrollably in 1979: the more-than-70-tonne US Skylab I crashed through the atmosphere and scattered debris across the Indian Ocean and Western Australia.
What Will Happen to This One on Entry?
The atmosphere will tear up the satellite. Aluminum parts and outer layers will burn. Twisted chunks of heavier pieces, like the fuel tank, could survive. McDowell says that the satellite could contain as much as a tonne of hydrazine, a highly toxic propellant which could be hazardous to be near but not dangerous when dispersed in the atmosphere.
Have Bits of Satellites Survived Re-entry Intact Before?
Yes. The NASA Orbital Debris Program Office hosts some pictures of pretty big chunks, including: a 250-kilogram steel fuel tank and a 30-kilogram titanium tank of a launch vehicle that both landed in Texas in 1997, and a 70-kilogram titanium rocket motor casing that landed in Saudi Arabia in 2001. One noteworthy ill-fated satellite actually crash — landed through the roof of a workshop supporting its launch in 2006, having fallen from a botched take-off.
How Many Things Are There That Could Potentially Fall Out of Orbit?
Yes. NASA Orbital Debris Program Office says there are some 11,000 objects bigger than 10 centimeters tracked by the US Space Surveillance Network. Of course, the biggest man-made object in the sky, by far, is the International Space Station. Nearly 45 meters long and more than 200 tones heavy, the concern about the ISS is in protecting it from debris, rather than worrying about it becoming debris itself.
If It Lands in the Middle of Nowhere, does It Matter?
While the impact is likely to be a nonevent, the falling satellite does serve as a reminder that the NRO — the United States "eyes and ears in space" — is having a bad time of things. In 2005, the NRO cancelled a next-generation reconnaissance technology project, called Future Imagery Architecture, after Boeing had spent more than $ 4 billion on it, according to the New York Times. "The NRO has had a bad decade," says Jeffrey Lewis, a space policy analyst at the New America Foundation in Washington DC. "We knew this satellite has been dead for a long time. But it reminds us of how much trouble they’ve had."
How would McDowell like the idea that people should be warned of the coming crash?
选项
A、It is a good idea.
B、It is reasonable.
C、It is useless.
D、It is unnecessary.
答案
D
解析
题目中be warned of the coming crash是原文中get alarmed about it的同义转换。文中McDowell分析了这颗卫星坠入居民区的概率,他认为概率很小没必要警告,因此正确答案是D。
转载请注明原文地址:https://kaotiyun.com/show/8s07777K
0
大学英语四级
相关试题推荐
A、Chocolatecake.B、Icecreamwithoutsugar.C、Chocolateicecream.D、Chocolatecakeandicecream.C
CluestoHelpExplaintheFrequencyofInjuriesThethreewomenareallseriousathletes,andtheyworktogetheratasmall
1.简介中国大学近年扩招情况2.大学扩招可能带来的问题3.采取相关措施解决问题
Manyteachersbelievethattheresponsibilitiesforlearningliewiththestudents.【C1】______alongreadingassignmentisgiven,
Theprincipaltechniqueincurrentuseforteachingreadingattheintermediatestageisthatofsupplementary,gradedreaders.
Adeviceto"sleeponit"couldbewellfounded,scientistssay.Afteragoodnight’ssleep,aproblemthatseemedinsurmountabl
Adeviceto"sleeponit"couldbewellfounded,scientistssay.Afteragoodnight’ssleep,aproblemthatseemedinsurmountabl
Earthquakesmayrightlyberankedasoneofthemostdevastatingforcesknowntoman:sincerecordsbegantobewrittendown,it
Fallingdownamanholeisnotthebestwaytomakeagoodimpression.OrsoIthoughtbeforecomingtoChina.Oneday,【B1】_____
A、Thenextbusiscomingsoon.B、Thebuswillwaitafewminutesatthestop.C、Thereareonlytwoorthreepassengerswaitingf
随机试题
试油不仅能为编制油田开发方案提供依据,而且能为新区块勘探指明方向。()
A、天麻丸B、木瓜丸C、痛风定胶囊D、尪痹颗粒E、风湿骨痛胶囊患者,男,69岁。患风湿性关节炎,症见腰脊疼痛、四肢关节冷痛。证属寒湿闭阻经络,治当温经散寒、通络止痛,宜选用的成药是()。
患者,女性,72岁。肺气肿病史15年。近日咳嗽、咳痰、气促、精神差。查体:口唇发绀,呼吸30/分,神志恍惚,多汗和皮肤湿暖,肋骨上抬,肋间隙增宽:动脉血气分析:pH7.31,PaO26.7kPa,PaCO28kPa。该患者最可能患有
某偏心受压柱,采用C50混凝土,HRB400级钢筋,则其相对界限受压区高度ζb=______。
2019年2月5日,A公司按照合同约定向B公司交付价值100万元的货物,B公司于2019年2月10日向A公司签发了一张见票后1个月内付款、金额为100万元的银行承兑汇票。2019年2月25日,A公司向C银行提示承兑并于当日获得承兑。2019年3月10日,A
岁末年终,在众多高校毕业生奔波穿梭于各类招聘会,承受焦虑忐忑、打击失落的时候,有部分学子却悄然选择了“回炉”上技校。据说今年仅广州便有3000人“刚出象牙塔又进技校门”,大学生“回炉”已从个体行为演变为群体现象,还呈快速“升温”趋势。下列选项中,对
根据我国《治安管理处罚法》,治安管理处罚的种类有()。
(1)报名(2)面试(3)上班(4)招聘公告发布(5)笔试
兴趣测量的方法有哪几种?
WaltDisneyCo.’sboardofdirectorswasre-electedbyamarginof92.2percentinapreliminarycountofashareholdervoteann
最新回复
(
0
)