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
If you were on a distant planet, and if you had instruments that could tell you the composition of Earth’s atmosphere, how would
If you were on a distant planet, and if you had instruments that could tell you the composition of Earth’s atmosphere, how would
admin
2012-03-04
18
问题
If you were on a distant planet, and if you had instruments that could tell you the composition of Earth’s atmosphere, how would you know there was life on this planet?
Water in the atmosphere would suggest there could be water on the surface, and as we all know water is considered crucial to life. But water would only suggest that life is possible. It wouldn’t prove it’s there.
Carbon? That basic component of "life as we know it?" Not necessarily. A diamond is pure carbon, and it may be pretty, but it isn’t alive.
What really sets Earth apart is nitrogen, which makes up 80 percent of the planet’s atmosphere. And it’s there only because there is abundant life on Earth, say scientists at the University of Southern California.
The report grew out of a class discussion two years ago in a course taught by Capone and Kenneth Nealson, professor of earth sciences. Students were asked to come up with different ideas about searching for life on other planets. What is a distinct "signature" , as Capone puts it, that would show there is life on another planet?
That’s a question that has been kicked around in many quarters in recent decades, especially since all efforts to find some form of life, no matter whether on Mars or in the distant reaches of space, have failed. At least so far.
The current effort to search for some evidence of life on Mars focuses primarily on the search for water, because it has long been believed that water, or at least some fluid, is necessary for the chemical processes that lead life to take place. But that’s probably the wrong approach, the USC group argues.
" It’s hard to imagine life without water, but it’s easy to imagine water without life," says Nealson, who was on the Mars team before moving to USC.
But nitrogen would be a much clearer signature of life. Only about 2 percent to 3 percent of the Martian atmosphere is nitrogen. That’s just a trace, and it probably means there is no life on Mars today, and if there was in the past, it probably ended many, many years ago.
But, the USC team adds quickly, that doesn’t mean there’s no life anywhere else in the universe. They don’t know where, of course, but they may have found a way to narrow down the search. Look first for nitrogen, then look for biological activity that should be there.
So if life exists elsewhere, and is similar to life as we know it, there should be nitrogen, and that’s what we should be looking for first, the researchers say.
If they don’t find nitrogen on Mars, Capone says, "that will probably bring us to the conclusion that there likely never was life on Mars. "
But how about elsewhere? Could this technique be used to search for life in other solar systems?
Maybe. It might be possible to detect a nitrogen - rich atmosphere around a planet orbiting another star, but not yet. Current instruments aren’t that sensitive.
If they ever are, the search for life might be narrowed down to the most promising prospects, chiefly because of the presence of nitrogen. And won’t that be fun!
What is considered as a wrong way to search for evidence of life on Mars?
选项
答案
The search for water
解析
转载请注明原文地址:https://kaotiyun.com/show/fNVK777K
本试题收录于:
C类竞赛(非英语专业本科)题库大学生英语竞赛(NECCS)分类
0
C类竞赛(非英语专业本科)
大学生英语竞赛(NECCS)
相关试题推荐
DoSomethingtoImproveYourLifeWrongopinionstowardslife.wrongopinions—peoplehavetoacceptwhateverlife【
"It’sashamethatthecityofficialshouldhavegonebackonhisword."ThemodalauxiliarySHOULDexpresses________.
A、Landscapepaintings.B、Traditionalart.C、Photosofnature.D、Abstractmodernart.D由原文可知,女士喜欢现代抽象艺术;女士认为风景画或更加传统的艺术有点无聊。因此答案为
A、Becausehewaswearingstrangeclothes.B、BecausehebrokesomethingatthepartyC、Becausehetalkedaboutmoneyinpublic.D
WhichofthefollowingitalicizedpartsisINCORRECT?
________theattemptedrescuemission,thehostagesmightstillbealive.
A、Theyarehardtoproduce.B、Theyareavailableinafewshops.C、Theyaremorepopularthanregularbabyfoodnow.D、Theyare
NowI’dlikeyoutospendfiveminutestalkingaboutthetopic;What______youdoifyou______President?
Conventionalwisdomsaystreesaregoodfortheenvironment.Theyabsorbcarbondioxide—agreenhousegas—fromtheatmosphereand
A、Histeacher.B、Hisboss.C、Hismother.B
随机试题
感染性休克病人,经积极抗休克治疗无好转,拟早期一次静脉滴注地塞米松。下述哪个不是其抗休克作用
A、非处方药B、处方药C、现代药D、新药E、传统药不需凭执业医师或执业助理医师处方即可自行判断,购买和使用的药品是
若诊断逆行性牙髓炎,探诊检查最重要的发现是
甲股份有限公司为注册地在上海市的一家上市公司(以下简称甲公司),其2007年至2011年与固定资产有关的业务资料如下:(1)2007年12月12日,甲公司购进一台不需要安装的设备,设备取得成本为409.5万元,另发生运输费1.5万元,款项以银行存款支付;
方先生为境内某上市公司雇员,每月工资3000元。2014年6月28日,该公司实行股票期权计划,授予方先生不可公开交易的股票期权50000股,授予价2.5元/股,并约定2014年12月28日起方先生可以行权,行权前不得转让。2014年12月28日方先生以授予
适用于融资租赁交易的租赁物为()。
材料:吴老师是一名数学老师,学生得高分是他的教学目标。他也比较偏爱那些数学成绩好的同学,而对于数学成绩不好的同学吴老师总少了一丝耐心。冬日里的一次数学课上,平时成绩较差又比较调皮的王明因为听不懂老师所讲内容便低声向同桌请教,吴老师见此情景后觉得是王明
各品种的葡萄中都存在着一种化学物质,这种物质能有效地减少人血液中的胆固醇。这种物质也存在于各类红酒和葡萄汁中,但白酒中不存在。红酒和葡萄汁都是用完整的葡萄作原料制作的;白酒除了用粮食作原料外,也用水果作原料,但和红酒不同,白酒在以水果作原料时,必须除去其表
空中客车A380是法国空中客车公司的最新巨型客机,。也是全球载客量最大的客机。A380为双层四引擎客机,采用最高密度座位安排时可承载850名乘客,在典型三舱等配置(头等—商务—经济舱)下也可承载555名乘客。A380于2005年4月27日首飞成功,并于同年
Youmightbeoftheopinionthatalittlehardworkneverhurtanyone,butthisoldsayingiswearingthin.Tokyointeriorsfilt
最新回复
(
0
)