Late last year, NASA, the U.S. space agency, announced plans to return to the moon by 2020. The goal is to have people living there by 2024. Today’s teens will be the right age by then to become lunar inhabitants.
The idea of building a base on the moon sounds exciting. NASA hasn’t sent an astronaut to the moon since 1972 — and that was just for a long weekend. Still, the idea is controversial3. Supporters see a lunar base as an important step toward human exploration of other planets. Opponents say little can be gained scientifically by sending people to inhabit4 the moon. What’s more, important robotic5 space missions are being sacrificed6 to pay for the moon project.
The Moon or Bust7?
Although the moon is the closest natural object to Earth in space, scientists still know little about it. “Why do we want to go back to the moon?” asks Clive Neal, a professor of geology and civil engineering at the University of Notre Dame. “We’ve sampled less than 5 percent of the lunar surface!”
Space scientists don’t know whether the moon has a core, as Earth does. Earth’s core is a super-hot blend of iron and nickel in two parts: a solid inner core and liquid outer core. The movement of the outer core is thought to cause the planet’s magnetic8 field.
NASA also says that lunar geologists will study moonquakes. The moon shakes like Earth, but no one knows why because the moon doesn’t have a shell that is divided into the gigantic, sliding tectonic9 plates that cause earthquakes here.
Neal heads a lunar exploration analysis group hired by NASA to assess10 the geological, commercial, and engineering aspects of the moon project. Building a lunar base, he says, will yield new technologies that could improve life on Earth. Moon-base advocates11 point out that products ranging from home insulation to medical scanning12 techniques were originally developed for the Apollo moon missions in the 1960s and 1970s. Current plans call for13 a moon base that would draw its energy from the sun and might lead to the development of more efficient solar-energy technology, supporters say.
The moon is also rich in helium-3, a form of helium14 that has one neutron15 instead of two in each atom and is rare on Earth. Some scientists think helium-3 might work as a fuel for nuclear fusion16 reactors17. Nuclear fusion occurs when the nuclei (central cores) of atoms fuse, producing energy but no radioactive18 waste.
Base-Less Science
The questions that geologists have about the moon are intriguing19. But sending people to the moon to investigate them is not scientifically useful, says Case Western Reserve University physicist Lawrence Krauss.
NASA’s robotic missions are far more scientifically important, says Krauss, and they cost a lot less than a moon base will. Robotic missions can study the moon, other planets, and distant stars, even Earth itself. However, some of those missions have lost funding because NASA needs money for its moon base project. The estimated price tag20 of the lunar base ranges from $100 billion to $1 trillion21 over 20 years.
Small Step, Giant Leap22?
For many moon-base supporters, science takes a backseat23 to human exploration. “The outpost24 on the moon is the first step in a long-term plan to move humans off this planet, and that doesn’t have much to do with science,” admits John Logsdon, director of the Space Policy Institute at George Washington University. “It has to do with the long-term destiny of the human species.”
In the future, humans may need to colonize25 other planets. A moon base would be an important experiment in extraterrestrial26 living, supporters say, and could be a launching pad27 for future human missions to the planet Mars.
Krauss says a manned mission to Mars is a distant dream compared with the real scientific opportunities being lost to pay for a moon base. However, Neal contends28 that manned missions and science go hand-in-hand. “You can’t do exploration without science,” he says, “and you can’t do science without exploration.”
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去年底美国宇航局宣布了在2020年前重返月球的计划，其目标是在2024年前送人到月球上居住。今天十多岁的孩子到那时恰好够格成为月球的居民。
在月球上建基地的想法听上去令人激动不已。1972年之后，美国宇航局就再未把宇航员送上过月球，——这段时间并不长，不过像一个漫长的周末。可是，人们对于建立月球基地的主意还是争论不休。支持者认为建立月球基地是人类探索其它星球的重要一步。反对者则说送人类到月球上居住不仅无利可图，而且为了支付登月计划的费用，一些由机器人执行的重要航天任务也被牺牲掉了。
登月还是破产？
虽然月球是宇宙中离地球最近的天体，但科学家对它了解甚少。“我们为什么要重返月球？” 美国圣母大学的地质学和土木工程学教授克莱夫·尼尔说，“因为我们的采样范围还不足月球表面的5%！”
航天科学家不知道月球是否像地球一样有一个核。地球的核是一个由铁和镍组成的超热混合体，它分为两个部分：一个固态内核和一个液态外核。外核的运动被认为是产生地球磁场的原因。
美国宇航局还称，月球地质学家将研究月震。月球的震动与地震相似，但没人知道为什么，因为月球不具有像地壳一样的由若干巨大滑移板块组成的外壳，这些板块的运动是导致地震的原因。
尼尔领导一个受雇于美国航天局的探月分析小组，对登月计划的地质、商业以及工程方面进行评估。他说，建造月球基地将催生一些新的技术，用于改善地球上的生活质量。月球基地的倡导者们指出，从家用绝缘材料到医学扫描技术等领域的产品都源于上世纪六十和七十年代的阿波罗登月计划。支持者说，目前的计划需要建造一个可以利用太阳能的月球基地，并由此开发更高效的太阳能技术。
月球还拥有丰富的氦-3。氦-3是氦的一种形式，它的每个原子中有一个中子而不是两个，在地球上十分罕见。有些科学家认为氦-3可用作核聚变反应堆的一种燃料。原子核熔合时发生核聚变反应，该反应产生能源，但不生成放射性废物。
无根据的科学
地质学家提出的有关月球的问题引人入胜，但凯斯西部保留地大学的物理学家劳伦斯·克劳斯说，把人送上月球去考察这些问题在科学上没有什么意义。
克老斯说，美国宇航局的机器人探测计划从科学的角度看更加重要，它们所需的花费比建立月球基地要少得多。使用探测器的太空计划可研究月球、其它行星和遥远的星体，甚至地球自身。然而，这些计划的一部分已失去了资助，因为美国宇航局需要资金来建立月球基地。预计在未来二十年，建立月球基地所需的费用将高达一千亿至一万亿美元。
小步抑或飞跃？
对于许多支持在月球上建立基地的人而言，科学的重要性次于人类探月。“到月球上建立前哨站是将人类从地球迁移的长远规划的第一步，与科学没多大关系，”乔治·华盛顿大学太空政策研究所所长约翰·罗格斯顿承认，“它关系到人类的长远命运。”
将来人类可能需要征服其它星球。支持者说，建立月球基地将是一个开发地球以外生存空间的重要实验，还可作为未来人类登陆火星的发射场。
克劳斯说，与那些为建月球基地而失去的切实可行的科学探测机会相比，载人登陆火星的计划只是一个遥远的梦想。然而，尼尔主张载人计划和科学携手并进。他说：“探索离不开科学，科学也离不开探索。”
1. stellar [?謖stel?藜] adj. 卓越的，有才华的
2. lunacy [?謖lju?蘼n?藜si] n. 疯狂行为；精神病
3. controversial [?謣k?蘅ntr?藜?謖v?藜?蘼?蘩?藜l] adj. 有争议的
4. inhabit [in?謖h?覸bit] v. 居住于，栖息
5. robotic [?謖r?藜ub?蘅tik] adj. 机器人的
6. sacrifice [?謖s?覸krifais] v. 牺牲
7. bust [b?蘧st] adj. 破产的
8. magnetic [m?覸g?謖netik] adj. 有磁性的
9. tectonic [tek?謖t?蘅nik] adj. 地壳构造的
10. assess [?藜?謖ses] v. 评估
11. advocate [?謖?覸dv?藜kit] n. 倡导者，鼓吹者
12. scan [sk?覸n] v. 扫描
13. call for 需要，要求
14. helium [?謖hi?蘼lj?藜m] n. 氦
15. neutron [?謖nju?蘼tr?蘅n] n. 中子
16. fusion [?謖fju?蘼?廾?藜n] n. 核聚变
17. reactor [ri?謖?覸kt?藜] n. 反应堆
18. radioactive [?謖reidi?藜u?謖?覸ktiv] adj. 放射性的
19. intriguing [in?謖tri?蘼gi?耷] adj. 迷人的，引起兴趣的
20. price tag 价格标签
21. trillion [?謖trilj?藜n] n. 万亿
22. leap [li?蘼p] n. 飞跃，跳跃
23. take a backseat 处于次要位置
24. outpost [?謖autp?藜ust] n. 前哨
25. colonize [?謖k?蘅l?藜naiz] v. 殖民
26. extraterrestrial [?謣ekstr?藜t?藜?謖restri?藜l] adj. 地球外的，宇宙的
27. launching pad 导弹或火箭发射场
28. contend [k?藜n?謖tend] v. 主张，争辩