首页
登录
职称英语
As in the field of space travel, so in undersea exploration new technologies
As in the field of space travel, so in undersea exploration new technologies
游客
2024-07-30
47
管理
问题
As in the field of space travel, so in undersea exploration new technologies continue to appear. They share a number of similarities with each other—as well as some important differences.
Manned submersibles, like spaceships, must maintain living conditions in an unnatural environment. But while a spaceship must simply be sealed against the vacuum space, a submersible must be able to bear extreme pressure if it is not to break up in deep water.
In exploring space, unmanned vehicles were employed before astronauts. In undersea exploration, on the other hand, men paved the way, and only recently have unmanned remote-operated vehicles been put to use.
One reason for this is that communicating with vehicles in orbit is much easier than talking to those underwater. A vacuum is an ideal medium for radio communications, but underwater communications are limited to much slower sound waves. Thus, most undersea vehicle—particularly remote-operated vehicles—operated at the end of long ropes.
For a similar reason, knowing where you are undersea is much more difficult than in space. A spaceship’s position can be located by following its radio signal, or by using telescopes and radar. For an undersea vehicle, however, a special network of sonar devices must be laid out in advance on the ocean floor in the area of a dive to locate the vehicle’s position.
Though undersea exploration is more challenging than outer space in a number of respects, it has a distinct advantage: Going to the ocean depths doesn’t make it necessary to escape the Earth’s gravity. Thus, it remains far less expensive.
选项
答案
communication problem
解析
转载请注明原文地址:http://tihaiku.com/zcyy/3697910.html
相关试题推荐
Whydidn’tpeoplebegintouseunmannedvehiclesinunderseaexplorationuntilr
Whydidn’tpeoplebegintouseunmannedvehiclesinunderseaexplorationuntilr
Whydidn’tpeoplebegintouseunmannedvehiclesinunderseaexplorationuntilr
Formanyyears,Hawaiihasbeenamagicnametopeoplewholiketotravel.P
Formanyyears,Hawaiihasbeenamagicnametopeoplewholiketotravel.P
Formanyyears,Hawaiihasbeenamagicnametopeoplewholiketotravel.P
Formanyyears,Hawaiihasbeenamagicnametopeoplewholiketotravel.Pe
Thousandsofyearsago,travelingwasveryhard.Therewerenoroadsandnoc
Asageneralrule,it’sdangeroustotravelina(law)______country.lawless根据题
TRAVELTIPSNoSmokingFeder
随机试题
Justiceinsocietymustincludebothafairtrialtotheaccusedandthesel
Itisdifficulttoimaginewhatlifewouldbelikewithoutmemory.Themeani
[originaltext]M:Hey,Christine,rememberhowwewerecomplainingthatwewante
Britain’spressisunusual______itisdividedintotwoverydifferenttypesofn
MostChineseAmericansworkedinrestaurantsandlaundriesbecauseof______.[br
当水喷雾系统用于冷却甲B、乙、丙类液体储罐时,关于冷却范围及保护面积的说法,下列
A.黑睛 B.两眦血络 C.眼睑 D.白睛 E.瞳仁根据眼的五轮分属,属
便秘冷秘的临床特征是A.大便不干,腰膝酸软 B.大便干结,欲便不得 C.
Thechangeinthatvillagewasmiraculou
双黄连口服液具有疏风解表、清热解毒的功效。主要用于外感风热所致的感冒,症见发热、
最新回复
(
0
)