首页
登录
职称英语
If you were on a distant planet, and if you had instruments that could tell
If you were on a distant planet, and if you had instruments that could tell
游客
2024-08-18
8
管理
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! [br] 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://tihaiku.com/zcyy/3724606.html
相关试题推荐
Ifyouwereonadistantplanet,andifyouhadinstrumentsthatcouldtell
Ifyouwereonadistantplanet,andifyouhadinstrumentsthatcouldtell
Mercury,theplanetnearestthesun,isdifficulttoobservefromtheEarth
Mercury,theplanetnearestthesun,isdifficulttoobservefromtheEarth
Newtechnologylinkstheworldasneverbefore.Ourplanethasshrunk.It’s
Newtechnologylinkstheworldasneverbefore.Ourplanethasshrunk.It’s
Beyondtheorbitofourplanet______theredworldofMars.Ifyoulookatitthr
TonyWheeleristhemanbehindtheLonelyPlanetguidebooks,bookswhichare
TonyWheeleristhemanbehindtheLonelyPlanetguidebooks,bookswhichare
TonyWheeleristhemanbehindtheLonelyPlanetguidebooks,bookswhichare
随机试题
【S1】[br]【S6】A、increasingB、collectingC、diminishingD、accumulatingD语义题。利己主义不仅
(1)Abouttwo-thirdsoftheworld’spopulationisexpectedtoliveincities
Virtuallyallconsumerswillhaveacreditcardintheirlives.Selectingac
从所给的四个选项中,选择最合适的一个填入问号处,使之呈现一定的规律性:
教学过程有哪些特点?
为了获取盈利,商业银行在正常范围内可以建立()的资产负债期限结构。A.借短贷短
股指期货合约的交割采用实物交割方式。( )
选择与求助者的谈话方式时,应当考虑的求助者自身因素包括()A.年龄特征 B
下列建设工程,不需申请消防设计审核的是( )。A.政府办公楼 B.城市轨道交通
承包人以欺诈、胁迫的手段,使发包人在违背真实意思的情况下订立了施工合同,则发包人
最新回复
(
0
)