VOA标准英语10月-Snow Falling From Martian Atmosphere

The U.S. space agency NASA's Mars probe Phoenix¹ has detected icy snow falling through the Martian atmosphere. The spacecraft has also discovered material in the planet's soil that is leading scientists a step closer in their conclusion that life probably existed at one time on the red planet. VOA's Jessica Berman reports.
　

Soil sample taken from informally named 'Snow White' trench2 at NASA's Phoenix Mars Lander work site produced minerals that indicate evidence of past interaction between the minerals and liquid water

Icy snow falls through the atmosphere of Mars. That finding was beamed back to Earth by the space probe Phoenix, which has been continuously monitoring the weather on the red planet since it landed four months ago.

Jim Whiteway is lead scientist for NASA's Phoenix meteorologist mission. "The ice crystals would be starting out at about a height of about four kilometers. And by the end of the measurement, in this case, they have fallen all the way down to about to 2.5 kilometers," he said. "So that is snow is falling from the clouds and we are going to be watching very closely over the next month for evidence that snow is actually landing on the surface."

Snow, which began falling about a month ago, is not the only surprising finding announced this week by managers of NASA's Phoenix mission.

The space probe discovered materials in the Martian soil that can only be produced through the interaction with water. These include a silicate³ mineral and calcium⁴ carbonate, according to senior project scientist William Boynton.

"Carbonates are very common minerals on Earth," he said. "They commonly form by the interaction of liquid water with carbon dioxide gas. And that is just what we think is going on in the surface of Mars. Another form in which people are familiar is just common chalk that you use for writing on black boards."

The Phoenix mission was undertaken because scientists believed there was ice just below the surface of the northern planes of Mars, something that was confirmed by the space probe shortly after it landed.

NASA principal investigator⁵ Peter Smith says the evidence points more and more to the conclusion that there was once life on Mars.

Smith notes that Mars was probably a much warmer planet millions of years ago because an unstable⁶ spin placed Mars' northern pole more directly toward the Sun. A warmer climate suggests the presence of liquid water and the existence of life, according to Smith.

"Is this a habitable zone on Mars? Well, I think we are approaching that hypothesis," he said. "We understand though that Mars has many surprises for us and we have not finished our investigation⁷ and so it is too soon to be sure of this, but we are certainly finding a lot of the indicators⁸ that we proposed to find at the beginning of this mission."

With the approaching winter and freezing temperatures, Phoenix is not expected to continue its research mission for many more weeks to learn, among other things, whether snow crystals reach the ground. But NASA investigators⁹ hope to jump start the space probe once Martian daylight returns.

1 phoenix   

n.凤凰，长生(不死)鸟；引申为重生

参考例句：

• The airline rose like a phoenix from the ashes.这家航空公司又起死回生了。
• The phoenix worship of China is fetish worship not totem adoration.中国凤崇拜是灵物崇拜而非图腾崇拜。

2 trench   

n./v.(挖)沟，(挖)战壕

参考例句：

• The soldiers recaptured their trench.兵士夺回了战壕。
• The troops received orders to trench the outpost.部队接到命令在前哨周围筑壕加强防卫。

3 silicate   

n.硅酸盐

参考例句：

• There are large amounts of aluminum silicate in the area.这个地区有大量的硅酸铝。
• Silicate minerals are characteristically refractory and difficult to break down.硅酸盐矿物的特点是耐熔和难以分离。

4 calcium   

n.钙(化学符号Ca)

参考例句：

• We need calcium to make bones.我们需要钙来壮骨。
• Calcium is found most abundantly in milk.奶含钙最丰富。

5 investigator   

n.研究者，调查者，审查者

参考例句：

• He was a special investigator for the FBI.他是联邦调查局的特别调查员。
• The investigator was able to deduce the crime and find the criminal.调查者能够推出犯罪过程并锁定罪犯。

6 unstable   

adj.不稳定的，易变的

参考例句：

• This bookcase is too unstable to hold so many books.这书橱很不结实，装不了这么多书。
• The patient's condition was unstable.那患者的病情不稳定。

7 investigation   

n.调查，调查研究

参考例句：

• In an investigation,a new fact became known, which told against him.在调查中新发现了一件对他不利的事实。
• He drew the conclusion by building on his own investigation.他根据自己的调查研究作出结论。

8 indicators   

（仪器上显示温度、压力、耗油量等的）指针( indicator的名词复数 )； 指示物； （车辆上的）转弯指示灯； 指示信号

参考例句：

• The economic indicators are better than expected. 经济指标比预期的好。
• It is still difficult to develop indicators for many concepts used in social science. 为社会科学领域的许多概念确立一个指标仍然很难。

9 investigators   

n.调查者，审查者( investigator的名词复数 )

参考例句：

• This memo could be the smoking gun that investigators have been looking for. 这份备忘录可能是调查人员一直在寻找的证据。
• The team consisted of six investigators and two secretaries. 这个团队由六个调查人员和两个秘书组成。 来自《简明英汉词典》