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
Since ancient times, people have dreamed of leaving their home planet and exploring other worlds. In the later half of the 20th
Since ancient times, people have dreamed of leaving their home planet and exploring other worlds. In the later half of the 20th
admin
2011-02-11
46
问题
Since ancient times, people have dreamed of leaving their home planet and exploring other worlds. In the later half of the 20th century, that dream became reality. The space age began with the launch of the first artificial satellites in 1963. A human first went into space in 1963. Since then, astronauts and cosmonauts have ventured into space for ever greater lengths of time, even living aboard orbiting space stations for months on end. Two dozen people have circled the moon or walked on its surface. At the same time, robotic explorers have journeyed where humans could not go, visiting all but one of the solar system’s major worlds. Unpiloted spacecraft have also visited a host of minor bodies such as moons, comets, and asteroids. These explorations have sparked the advance of new technologies, from rockets to communications equipment to computers. Spacecraft studies have yielded a bounty of scientific discoveries about the solar system, the Milky Way Galaxy, and the universe. And they have given humanity a new perspective on the earth and its neighbors in space.
The first challenge of space exploration was developing rockets powerful enough and reliable enough to boost a satellite into orbit. These boosters needed more than brute force, however; they also needed guidance systems to steer them on the proper flight paths to reach their desired orbits. The next challenge was building the satellites themselves. The satellites needed electronic components that were lightweight, yet durable enough to withstand the acceleration and vibration of launch. Creating these components required the world’s aerospace engineering facilities to adopt new standards of reliability in manufacturing and testing. On Earth, engineers also had to build tracking stations to maintain radio communications with these artificial "moons" as they circled the planet.
Beginning in the early 1920s, humans launched probes to explore other planets. The distances traveled by these robotic space travelers required travel times measured in months or years. These spacecraft had to be especially reliable to continue functioning for a decade or more. They also had to withstand such hazards as the radiation belts surrounding Jupiter, particles orbiting in the rings of Saturn, and greater extremes in temperature than are faced by spacecraft in the closeness of Earth. Despite their great scientific returns, these missions often came with high price tags. Today the world’ s space agencies, such as the United States National Aeronautics and Space Administration (NASA. and the European Space Agency (ESA), strive to conduct robotic missions more cheaply and efficiently.
It was inevitable that humans would follow their unpiloted creations into space. Piloted space flight introduced a whole new set of difficulties, many Of them concerned with keeping people alive in the hostile environment of space. In addition to the vacuum of space, which requires any piloted spacecraft to carry its own atmosphere, there are other deadly hazards: solar and cosmic radiation, micrometorites (small bits of rock and dus0 that might puncture a spacecraft hull or an astronaut’ s pressure suit, and extremes of temperature ranging from frigid darkness to broiling sunlight. It was not enough simply to keep people alive in space — astronauts needed to have a means of accomplishing useful work while they were there. It was necessary to develop tools and techniques for space navigation, and for conducting scientific observations and experiments. Astronauts would have to be protected when they ventured outside the safety of their pressurized spacecraft to work in the vacuum. Missions and hardware would have to be carefully designed to help insure the Safety of space crews in any foreseeable emergency, from liftoff to landing.
The challenges of conducting piloted space flights were great enough for missions that orbited Earth. They became even more daunting for the Apollo missions, which sent astronauts to the moon. The achievement of sending astronauts to the lunar surface and back represents a summit of human space flight.
After the Apollo program, the emphasis in piloted missions shifted to long-duration spaceflight, as pioneered aboard Soviet and U.S. space stations. The development of reusable spacecraft became another goal, giving rise to the U.S. space shuffle fleet. Today efforts focus on keeping people healthy during space missions lasting a year or more — the duration needed to reach nearby planets — and in lowering the cost of sending satellites into orbit.
In the passage, the author wants to tell us______.
选项
A、that people dreamed of leaving their home planet and exploring other worlds became reality
B、after the Apollo program, the emphasis in piloted missions shifted to short-duration spaceflight
C、space exploration is a great challenge to human beings and will be achieved through generation’s work
D、today efforts focus on keeping people healthy during space missions and in increasing the cost of sending satellites into orbit
答案
C
解析
理解全文不难解答。
转载请注明原文地址:https://kaotiyun.com/show/UeeO777K
0
专业英语八级
相关试题推荐
Storytellingisanancientandhonoredart.Storytellersentertainedduringthelongdarkhoursbeforesleeparrivedafterthe
Computerprogrammersoftenremarkthatcomputingmachines,withaperfectlackofdiscrimination,willdoanyfoolishthingthey
Computerprogrammersoftenremarkthatcomputingmachines,withaperfectlackofdiscrimination,willdoanyfoolishthingthey
SomeofthemostbasicconceptsofpsychologyweredefinedbySigmundFreudandtwoofhisfollowers,AlfredAdlerandCarlGust
Whyshouldanyonebuythelatestvolumeintheever-expandingDictionaryofNationalBiography?Idonotmeanthatitisbad,as
A、multibillion-dollarbidB、athlete-orientedfocusC、plansforanOlympicparkD、diversityofculturalbackgroundBA数十亿美元的申办
TonyBlairmayinterviewinthe______withofficialscomingfromforeigncountries.
A、ThisisthebiggesttakeoverbattleforChinaB、China’sbidwillprobablytriggeracostlybidingcompetitionoverthecompan
A、Accordingtothemovementandvibrationsofhotgasses.B、ThetradewindsblowonEarth.C、Therivers.D、Thesoundtravelthro
GoingForth,TheNationsMultiplyUnevenlyDespitewas,famines,andepidemics,Earth’spopulationisboomingaheadtonewre
随机试题
王老师所教的班有这样两位学生:学生甲在采取决定和执行决定时,常因缺乏信心而患得患失、犹豫不决、顾虑重重,长时间处于内心冲突状态;学生乙在采取和执行决定中,往往只有三分钟的热情,一旦遇到困难或挫折便垂头丧气,望而却步,半途而废。问题:甲和乙两位
患儿,女,1岁,生后3个月起青紫渐加重,活动后气急,查体:生长发育明显落后,口唇、鼻尖、耳垂、指、趾青紫明显,伴杵状指(趾),胸骨左缘闻及Ⅲ级收缩期杂音,肺动脉第二心音减弱。该患儿应该采取的体位是
中国法院就一家中国公司和一家瑞士公司之间的技术转让纠纷作出判决。判决发生效力后,瑞士公司拒不执行法院判决,而且该公司在中国既无办事机构、分支机构和代理机构,也无财产。关于该判决的承认和执行,下列选项中的哪些表述是正确的?
设备制造的总工期目标可以分解为许多相对独立的分目标,分项目标是指( )。
()是资金需求者最基本的筹资手段。
20×9年,甲企业与乙科研所签订了一份《委托开发合同》,委托乙科研所研发一项技术,合同中对专利权的归属没有约定。若乙科研所最终成功研发出该项技术成果,则申请专利的权利归甲企业所有。()
第一次工业革命使西欧国家的阶级结构发生了变化,其中力量得到加强的是()。①自由派贵族②工业资产阶级③金融资产阶级④工业无产阶级
研究人员选取英国近4000名年龄在52岁到79岁之间的老人,调查他们的精神状况和死亡风险。结果显示,在平均为期5年的跟踪调查期间,快乐程度最低的老人群体死亡率为7.3%,而快乐程度最高的老人群体死亡率只有3.6%。因此,快乐有利于健康和长寿。下列各项如果为
甲明知王某是逃犯,在公安人员前来抓捕王某时,给其3000元帮其逃跑,甲的行为构成()(2016年一专一第9题、2016年一法专一第8题)
近年来,伴随互联网行业的快速发展,非法删帖、发帖中伤、泄露隐私等利用信息网络侵权行为频发,个人信息保护迫在眉睫。10月9日,最高人民法院通报《关于审理利用信息网络侵害人身权益民事纠纷案件适用法律若干问题的规定》,该《规定》()
最新回复
(
0
)