首页
登录
职称英语
What forms of radiation are feared by astronauts? [br] [originaltext] Not l
What forms of radiation are feared by astronauts? [br] [originaltext] Not l
游客
2023-11-13
60
管理
问题
What forms of radiation are feared by astronauts? [br]
Not long ago it was assumed that the dangers man would meet in Space would be terrible, the main ones being radiation and the danger of being hit
by meteors. It is perhaps worth remembering that less than two centuries ago the dangers of train travel seemed similarly terrible. A man would certainly die, it was thought, if carried along at a speed of thirty kilometers per hour.
There are two sorts of radiation man must fear in space. The first is radiation from the sun, and this is particularly dangerous when the sun is very ac five and explosions are occurring on its surface. The second, less harmful form comes from the so-called Van Allen Belts. These are two areas of radiation about 1 ,500 miles away from the earth. Neither of these forms of radiation area is dangerous to us on the earth, since we are protected by our atmosphere. Specifically, it is that part of our atmosphere known as the ozonosphere which protects us. This is a belt of the chemical ozone between 12 and 21 miles from the ground, which absorbs all the radiation.
Once outside the atmosphere, however, man is no longer protected, and radiation can be harmful in a number of ways. A distinction must be drawn between the short- and long-term effects of radiation. The former are merely unpleasant, but just because an astronaut returning from a journey in space does not seem to have been greatly harmed, we cannot assume that he is safe. The long-term effects can be extremely serious, even leading to death.
选项
A、Between 12 and 21 miles.
B、1,000 miles.
C、150 miles.
D、1,500 miles.
答案
D
解析
转载请注明原文地址:http://tihaiku.com/zcyy/3184557.html
相关试题推荐
WhatdestroyedSaint-Pierre?[originaltext]PeoplesaidthatSaint-Pierrewa
Whatisthemainsubjectofthistalk?[br][originaltext]Goodafternoon,
Whatistheconversationfocusedon?[br][originaltext]W:Ipersonally,um,do
Accordingtothepolls,whichpartytakestheleadatpresent?[originaltext]
Whothespeakerspeakingto?[br][originaltext]MayIhavetheattentionof
Whothespeakerspeakingto?[originaltext]MayIhavetheattentionofalls
whyistheweightlossplancalledtheScarsdalediet?[br][originaltext]
whyistheweightlossplancalledtheScarsdalediet?[br][originaltext]
Whatisthetalkmainlyabout?[br][originaltext]The23rdOlympicgameswe
Whatisthetalkmainlyabout?[br][originaltext]The23rdOlympicgameswe
随机试题
[img]ct_epem_epelisv_01171(20097)[/img][br][originaltext]Weshouldkeepsilen
-Owingtoincreasedbusinessinyourdepartmentyourdirectorwantedtorecruit
WhydidMetcalfwritethisletter?Metcalfwrotethislettertocomplainabout_
[audioFiles]audio_eufm_j49_001(20082)[/audioFiles]A、ShewilltalktoJudyabout
隐藏命令窗口的组合键是A.Ctrl+F2 B.Ctrl+F4 C.Ctrl+
患者,男,12岁。大便水泻,并见轻微发热,恶心欲吐症状。舌质淡,舌苔白腻,脉象濡
2015年1月1日,甲、乙、丙、丁共同设立A有限合伙企业,甲、乙为普通合伙人,丙
可乐定的降压机制是A.激动外周α1受体 B.影响NA.释放 C.扩张血管
简述学校开展心理健康教育的基本途径。
常用的给水处理方法有( )。A.过滤 B.浓缩 C.消毒 D.软化 E
最新回复
(
0
)