Mars rover Spirit ends mission

     LOS ANGELES, May 25 (Xinhua) -- NASA project managers bade farewell to the Mars rover Spirit on Wednesday after sending a final set of commands to the stranded¹ vehicle.

    This marks the completion of one of the most successful missions of interplanetary exploration ever launched, NASA's Jet Propulsion Laboratory (JPL) said.

    "Last night, just after midnight, the last recovery command was sent to Spirit," said John Callas, the Mars Exploration Rover Project manager at NASA's Jet Propulsion Laboratory (JPL) in Pasadena, Los Angeles.

    "It would be an understatement to say this was a significant moment. Since the last communication from Spirit on March 22, 2010, as she entered her fourth Martian winter, nothing has been heard from her."NASA has tried in vain to regain² communication with Spirit since it got stuck in sand about two years ago. The rover last communicated on March 22, 2010, as Martian winter approached and the rover's solar-energy supply declined.

    NASA checked frequently in recent months for possible reawakening of Spirit as solar energy available to the rover increased during Martian spring, but to no avail.

    A series of additional re-contact attempts ended on Wednesday, designed for various possible combinations of recoverable conditions, according to JPL.

    "Our job was to wear these rovers out exploring, to leave no unutilized capability³ on the surface of Mars, and for Spirit, we have done that," said Callas.

    With the completion of Spirit's mission, NASA will have to transition the Mars Exploration Rover Project to a single-rover operation focused on Spirit's still-active twin, Opportunity.

    Spirit operated for more than six years after landing in January 2004 for what was planned as a three-month mission. Its twin, Opportunity, landed on the other side of the planet three weeks after Spirit.

    Despite being stuck, the rover performed beyond expectations. It returned more than 124,000 images, ground the surfaces off 15 rock targets and scoured⁴ 92 targets with a brush to prepare the targets for inspection⁵ with spectrometers and a microscopic⁶ imager.

    "What's really important is not only how long Spirit worked or how far Spirit drove, but also how much exploration and scientific discovery Spirit accomplished," Callas said.

    Spirit started out with some problems in its electronic memory, but detected evidence of water-altered rocks and carbonates -- both building blocks of life -- on what scientists call the Gusev site.

    But the rover found evidence that Mars was once like Earth, with water and hot springs. Concentrated deposits of silica led the project's principal investigator⁷ to conclude that steam vents⁸ or hot springs once existed at a site known as Home Plate. Such an environment could have supported microbial life.

    After its first year on Mars, the rover lost the use of one of six wheels while scrambling⁹ over a hilly area, but continued to send data back to Earth for years. It logged 4.8 miles (about 7.7 km) over the Martian surface -- about a dozen times farther than it was expected to go.

    Opportunity is still working. It has logged 12 miles (19.2 km), collected more than 130,000 images and is headed toward a crater¹⁰ called Endeavour.

    NASA is currently preparing for the launch of another Mars rover Curiosity.

    "We're now transitioning assets to support the November launch of our next generation Mars rover, Curiosity," said Dave Lavery, NASA's program executive for solar system exploration.(本文由在线英语听力室整理编辑)

1 stranded   

a.搁浅的，进退两难的

参考例句：

• He was stranded in a strange city without money. 他流落在一个陌生的城市里， 身无分文，一筹莫展。
• I was stranded in the strange town without money or friends. 我困在那陌生的城市，既没有钱，又没有朋友。

2 regain   

vt.重新获得，收复，恢复

参考例句：

• He is making a bid to regain his World No.1 ranking.他正为重登世界排名第一位而努力。
• The government is desperate to regain credibility with the public.政府急于重新获取公众的信任。

3 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。

4 scoured   

走遍（某地）搜寻（人或物）( scour的过去式和过去分词 )； （用力）刷； 擦净； 擦亮

参考例句：

• We scoured the area for somewhere to pitch our tent. 我们四处查看，想找一个搭帐篷的地方。
• The torrents scoured out a channel down the hill side. 急流沿着山腰冲刷出一条水沟。

5 inspection   

n.检查，审查，检阅

参考例句：

• On random inspection the meat was found to be bad.经抽查，发现肉变质了。
• The soldiers lined up for their daily inspection by their officers.士兵们列队接受军官的日常检阅。

6 microscopic   

adj.微小的，细微的，极小的，显微的

参考例句：

• It's impossible to read his microscopic handwriting.不可能看清他那极小的书写字迹。
• A plant's lungs are the microscopic pores in its leaves.植物的肺就是其叶片上微细的气孔。

7 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。

8 vents   

（气体、液体等进出的）孔、口( vent的名词复数 )； （鸟、鱼、爬行动物或小哺乳动物的）肛门； 大衣等的)衩口； 开衩

参考例句：

• He always vents his anger on the dog. 他总是拿狗出气。
• The Dandelion Patch is the least developed of the four active vents. “蒲公英区”在这四个活裂口中是发育最差的一个。

9 scrambling   

v.快速爬行( scramble的现在分词 )；攀登；争夺；（军事飞机）紧急起飞

参考例句：

• Scrambling up her hair, she darted out of the house. 她匆忙扎起头发，冲出房去。 来自《现代英汉综合大词典》
• She is scrambling eggs. 她正在炒蛋。 来自《简明英汉词典》

10 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。