Spacecraft see 'damp' Moon soils

We are rediscovering the enigmas¹(谜团) of the Moon and they're really in our own backyard

Dr Jim Garvin, Nasa Goddard Space Flight Center


Moon water has world in a twitter
A surprising amount of water has been found to exist in the Moon's soil.

Data from three spacecraft, including India's Chandrayaan probe, shows that very fine films of H2O coat the particles that make up the lunar dirt.

The quantity（数量） is tiny but could become a useful resource for astronauts wishing to live on the Moon, scientists say.

"If you had a cubic metre of lunar soil, you could squeeze it and get out a litre of water," explained US moon researcher Larry Taylor.

The rock and soil samples returned by the Apollo missions were found to be ever so slightly "damp" when examined in the laboratory, but scientists could never rule out the possibility that the water in the samples got in only after they were hauled back to Earth.

The only safe scientific conclusion they could draw at the time was that the lunar surface was all but bone dry.

Now a remote（远程） sensing instrument on Chandrayaan-1, India's first mission to lunar orbit, has confirmed that there is a real H2O signal at the Moon.

Two other satellites to look at the Moon - the US Deep Impact probe and the US-European Cassini spacecraft - back up Chandrayaan.

Both collected Moon data before Chandrayaan was launched (in the case of Cassini, 10 years ago), but the significance of what they saw is only now being fully² realised.

Indian success

The quantity of water is seen to increase the closer the observations are made to the poles - the very places the Apollo missions never went.

Scientists suspect the water is created in the soil in an interaction with the solar wind, the fast-moving stream of particles that constantly billows away from the Sun.

Harsh space radiation triggers a chemical reaction in which oxygen atoms already in the soil acquire hydrogen nuclei³ to make water molecules⁵ and the simpler hydrogen-oxygen (OH) molecule⁴.

The amounts are small, say researchers, but boost the notion that astronauts based on the Moon could use it as a resource.


The LCROSS experiment will target a crater⁶ near the south pole
"If it is a little or a lot, it's easy enough to split into hydrogen and oxygen and then you have rocket fuel," said Professor Taylor, a University of Tennessee, Knoxville, researcher who has worked on the Chandrayaan data.

The Indian Moon mission was launched late last year but radio communication with it was abruptly（突然） lost in August. Nevertheless, the Indian space agency (Isro) will consider the water discovery a major triumph and a vindication⁷ of its endeavours.

A US space agency (Nasa) probe is due to impact the Cabeus A crater near the Moon's south pole next month to see if it can kick up sufficient soil so that another satellite and Earth-based telescopes can detect the presence of water vapour in the dusty plume⁸.

Researchers say the latest results, published online by the journal Science, give them confidence that the experiment performed by the Lunar Crater Observation and Sensing Satellite mission, known as LCROSS, could have a positive outcome.

They speculate that the water seen elsewhere on the lunar surface may migrate to the slightly cooler poles, much as water vapour on Earth will condense on a cold surface.

This cold sink effect could result in vast quantities of water being retained in permanently⁹ shadowed craters¹⁰ in the form of ice, especially if it has being supplemented by water delivered by comets.

'Exciting place'

Nasa's Lunar Prospector¹¹ probe in the late 1990s saw a strong hydrogen（氢） signal at high north and south latitudes¹². Some scientists on the mission suggested there could be up to 300 million tonnes of water-ice buried in crater soils that never see sunlight.

Chandrayaan made its observations（意见） using a US-provided instrument, the Moon Mineralogy Mapper, or M3 for short.


The Apollo missions stayed close to the Moon's equator


The magic of Apollo
The M3 assessed the nature of lunar soils by analysing the way that light from the Sun was reflected off the surface.

It could only see the top few centimetres of soil. Nasa's Lunar Reconnaissance Orbiter, which is currently circling the Moon, has the capability¹³ to see down to nearly a metre. Its data could determine if the presence of water is much more extensive.

Dr Jim Garvin is the the chief scientist at the US space agency's Goddard Space Flight Center.

He was asked if he thought the Moon had become an exciting place again for science.

"I think it always was; it's just we saw this big exciting Solar System and after touching¹⁴ the Moon with six human missions, we moved on - to Mars, to the outer planets, to comets and asteroids¹⁵.

"And now we are rediscovering the enigmas of the Moon and they're really in our own backyard. They're tantalisingly close," he told BBC News. （本文由在线英语听力室整理编辑）

1 enigmas   

n.难于理解的问题、人、物、情况等，奥秘( enigma的名词复数 )

参考例句：

• The last words of Night Haunter stand as one of the great enigmas of Imperial history. 暗夜幽魂最后的临死前的话成为了帝国历史上的最大谜团之一。 来自互联网
• Heraclitus saith well in one of his enigmas, Dry light is ever the best. 赫拉克里塔斯在他的隐语之一中说得很好，“干光永远最佳”。 来自互联网

2 fully   

adv.完全地，全部地，彻底地；充分地

参考例句：

• The doctor asked me to breathe in,then to breathe out fully.医生让我先吸气，然后全部呼出。
• They soon became fully integrated into the local community.他们很快就完全融入了当地人的圈子。

3 nuclei   

n.核

参考例句：

• To free electrons, something has to make them whirl fast enough to break away from their nuclei. 为了释放电子，必须使电子高速旋转而足以摆脱原子核的束缚。
• Energy is released by the fission of atomic nuclei. 能量是由原子核分裂释放出来的。

4 molecule   

n.分子，克分子

参考例句：

• A molecule of water is made up of two atoms of hygrogen and one atom of oxygen.一个水分子是由P妈̬f婘̬ 妈̬成的。
• This gives us the structural formula of the molecule.这种方式给出了分子的结构式。

5 molecules   

分子( molecule的名词复数 )

参考例句：

• The structure of molecules can be seen under an electron microscope. 分子的结构可在电子显微镜下观察到。
• Inside the reactor the large molecules are cracked into smaller molecules. 在反应堆里，大分子裂变为小分子。

6 crater   

n.火山口，弹坑

参考例句：

• With a telescope you can see the huge crater of Ve-suvius.用望远镜你能看到巨大的维苏威火山口。
• They came to the lip of a dead crater.他们来到了一个死火山口。

7 vindication   

n.洗冤，证实

参考例句：

• There is much to be said in vindication of his claim.有很多理由可以提出来为他的要求作辩护。
• The result was a vindication of all our efforts.这一结果表明我们的一切努力是必要的。

8 plume   

n.羽毛；v.整理羽毛，骚首弄姿，用羽毛装饰

参考例句：

• Her hat was adorned with a plume.她帽子上饰着羽毛。
• He does not plume himself on these achievements.他并不因这些成就而自夸。

9 permanently   

adv.永恒地，永久地，固定不变地

参考例句：

• The accident left him permanently scarred.那次事故给他留下了永久的伤疤。
• The ship is now permanently moored on the Thames in London.该船现在永久地停泊在伦敦泰晤士河边。

10 craters   

n.火山口( crater的名词复数 )；弹坑等

参考例句：

• Small meteorites have left impact craters all over the planet's surface. 这个行星的表面布满了小块陨石留下的撞击坑。 来自《简明英汉词典》
• The battlefield was full of craters made by exploding shells. 战场上布满弹坑。 来自《现代英汉综合大词典》

11 prospector   

n.探矿者

参考例句：

• Although he failed as a prospector, he succeeded as a journalist.他作为采矿者遭遇失败，但作为记者大获成功。
• The prospector staked his claim to the mine he discovered.那个勘探者立桩标出他所发现的矿区地以示归己所有。

12 latitudes   

纬度

参考例句：

• Latitudes are the lines that go from east to west. 纬线是从东到西的线。
• It was the brief Indian Summer of the high latitudes. 这是高纬度地方的那种短暂的晚秋。

13 capability   

n.能力；才能；(pl)可发展的能力或特性等

参考例句：

• She has the capability to become a very fine actress.她有潜力成为杰出演员。
• Organizing a whole department is beyond his capability.组织整个部门是他能力以外的事。

14 touching   

adj.动人的，使人感伤的

参考例句：

• It was a touching sight.这是一幅动人的景象。
• His letter was touching.他的信很感人。

15 asteroids   

n.小行星( asteroid的名词复数 )；海盘车，海星

参考例句：

• Asteroids,also known as "minor planets",are numerous in the outer space. 小行星，亦称为“小型行星”，在外太空中不计其数。
• Most stars probably have their quota of planets, meteorids, comets, and asteroids. 多数恒星也许还拥有若干行星、流星、彗星和小行星。