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
The search for water—and possible life—on Mars got a boost this week as scientists announced evidence of an ancient ocean on the
The search for water—and possible life—on Mars got a boost this week as scientists announced evidence of an ancient ocean on the
admin
2018-06-06
45
问题
The search for water—and possible life—on Mars got a boost this week as scientists announced evidence of an ancient ocean on the planet’s northern plains.
The massive, sediment-filled basin surrounded by "shoreline-like" features was first spotted when scientists were mapping Mars’s surface using images from the late-1970s Viking missions.
The features made theories of an ancient Martian ocean quite popular—until NASA’s Mars Global Surveyor highlighted some seemingly insurmountable problems. The Arabia and Deuteronilus "shorelines" are thousands of kilometers long. But they undulate like a long wave, rising and falling in height as much as several kilometers(more than a mile)along their length. "That doesn’t seem to jibe with the idea that they are shorelines, because shorelines form at sea level," said lead author Taylor Perron, a postdoctoral fellow in Harvard University’s Department of Earth and Planetary Sciences.
But there really was an ocean there, Perron and colleagues now suggest in a finding that adds to a number of recent studies bolstering evidence of Mars’s watery past. The researchers believe that Mars’s poles, along with the axis the planet spins on, have moved about 1,850 miles(3,000 kilometers)during the past two or three billion years. The process, known as "true polar wander", can cause dramatic topographic changes in a planet’s surface—in this case making the once-flat shorelines rise and fall over enormous distances. "When the spin axis moves relative to the surface, the surface deforms, and that is recorded in the shoreline," said co-author Michael Manga, professor of earth and planetary science at the University of California, Berkeley.
On the Martian equator one finds the Tharsis rise—a massive bulge that holds the colossal volcano Olympus Mons. "The largest mountain in the solar system is sitting almost right on the equator, and that’s right where you should expect such a large surface load to be," Perron said. "That tells you that if Mars experienced any true polar wander after the creation of Tharsis, it should reorient in such a way that keeps Tharsis at the equator—a circle 90 degrees from Tharsis."
The current locations of the poles, along with calculations of their previous positions based on the deformation of the shorelines, suggest just such an alignment.
The findings are sure to spark debate among many professionals in search of a liquid "smoking gun" on the red planet. Jeff Moore, a planetary geologist at NASA’s Ames Research Center who is unaffiliated with the study, finds it plausible that early Mars had large standing bodies of water—either liquid or frozen. "But while the new study presents a possible explanation for why the shorelines don’t follow a constant contour, it’s not a conclusive one," Moore said.
NASA’s Mars Global Surveyor highlighted some seemingly insurmountable problems about the fact that______.
选项
A、there is no water on Mars
B、the Arabia and Deuteronilus "shorelines" are thousands of kilometers long
C、the shorelines founded by scientists are not formed at sea level
D、Mars didn’t have watery past
答案
D
解析
转载请注明原文地址:https://kaotiyun.com/show/boSO777K
本试题收录于:
NAETI中级口译笔试题库外语翻译证书(NAETI)分类
0
NAETI中级口译笔试
外语翻译证书(NAETI)
相关试题推荐
OntheInternet,adsarearealproblem.They’reaproblemforus,thepeople,andnotjustbecausetheyclutterupourWebpage
Howmuchphysicalactivityshouldteenagersdo,andhowcantheygetenough?Manyteenagersspendalot
Researchersallovertheworldhavebeenseekingfordetermininghowearlyinfancyconceptualthinkingispossible.
Everydepartmenthashadtheirbudget________duringthefinancialcrisis.
A、It’salargemuseum.B、Visitorswillhavetopaygointhere.C、Thereareawiderangeofthings,includingSamuraiarmor.D、I
A、Jackwearsatightshirt.B、WecangraspEnglishculturebeforegraduationwiththehelpofJack.C、Jackhasn’tgotenoughtim
A、Exactlyatthreeo’clock.B、Aroundthreeo’clock.C、Beforethreeo’clock.D、Afterthreeo’clock.B
Canyouspotagoodmarriage?IwasprettysureIcould,startingwithmyown.MyhusbandandIrarelyargued,wehadsimilarca
Canyouspotagoodmarriage?IwasprettysureIcould,startingwithmyown.MyhusbandandIrarelyargued,wehadsimilarca
Foracitypurportedtobedying,JohannesburglooksprettylivelyonaSaturdaymorning.Fleetsofminivansdeliverblackshopp
随机试题
布雷顿森林体系确定的国际储备货币是_________。
男性,25岁。3天前抬重物扭伤腰部。服用芬必得,卧床休息腰痛无缓解,出现右腿麻木,右直腿抬高40°~50°阳性,加强试验阳性。经检查诊断腰4~5椎间盘突出症,此时较合适的处理是
泻下药的主要功效不包括
碎石沥青混凝土(SAC)的试验技术指标包括()。
甲公司对A产品实行1个月内“包退、包换、包修”的销售政策。2005年1月份销售A产品100件,2月份销售A产品80件,A产品的销售单价均为5000元。根据2004年的经验,A产品包退的占4%、包换的占2%、包修的占6%。假设2005年2月份未出现退、换产
所谓会计监督,指的是会计人员进行()的同时,对特定对象经济业务的合法性、合理性进行审查。
关于儒释道文化的说法,正确的有()。
在关系模型中,若属性A是关系R的主码,则在R的任何元组中,属性A的取值都不允许为空,这种约束称为【】规则。
Ihaveworkedwithhimforsometimeandhavefoundthatheis______thanJohn.
TheancientAztecsveneratedthecacaotreeanduseditsbeansasaformofcurrency.They【C1】______thetreeasasourceofstre
最新回复
(
0
)