火星上的“凤凰”的生命已经终结

NASA于十一月十日正式宣布：于今年五月下旬登陆火星的探测器“凤凰”（Phoenix），经过五个月的紧张探测工作后，顺利完成了科学家们赋予它的使命，它的生命已经终结。

凤凰号原定的设计寿命是三个月，它已超期服役了两个月。

Phoenix 的主要任务是探测火星北极附近是否有水，所以，它的着陆地方离北极很近。现在，火星的北半球和地球北半球是一样的，进入冬季。太阳的光线照射角度很低。探测器又遭遇尘暴。它的太阳能板无法给电池充上足够的电力。科学家们最后一次收到它的信号是十一月五号。所以，宣布它的寿命已终结。

不过，在未来几周内，科学家们还会细心地倾听能否从火星还发来信号。估计这种可能性很低了。因为探测器一旦被冻死，几乎没有再复活的机会。正常情况下，在火星的晚上，探测器停止工作，仅供少量的电力加热关键部件，以免它被冻死。它无法活过火星北半球上的严酷冬季，不能像另两个火星探测器已经在火星上工作了四年多，现在仍然在工作。它们是在火星的赤道附近。

凤凰探测器的任务已完满地完成了。它通过采样化验，发现火星上地表下很浅的地方就有水冰。并发现有雪从空中落下，当然是很稀少的量。


1，这是凤凰探测器在火星表面掘出的沟。图片中的白色物，后来科学家们宣布是水冰。



2，这是凤凰号拍摄的照片。为火星的早上，地上有白霜。


它发回地球的数据会被科学家们仔细地研究，也许会揭开许多秘密。火星上曾经有过许多地表水。现在则很少了。一个问题自然是，它的水怎样消失的？科学家们会在未来的岁月里来回答这个问题。一种可能是：火星的个头相对地球是很小的，它内部的放射能早已耗尽。它在地质意义上讲是死了。地表的水在被宇宙的高能射线分解，逃逸到太空去了。而它的火山活动的停止，不再为地表提供水的补充。因而，它的水就慢慢地干涸了。

若地球上的火山完全停止喷发，不再把禁锢在地壳内的水释放出来补充在高空被宇宙高能射线分解的水分子。地球上的海洋也会慢慢干涸了，像今天的火星一样。当然，这个过程很缓慢。下次，你若再看到火山喷发，不要咒骂它。因为它对维持地球上生命有很重要的作用。

我们应向凤凰号表示敬意！

文中照片来源NASA 网站。

下面是NASA 网站宣布凤凰的任务完成的全文。



Mars Phoenix Lander Finishes Successful Work on Red Planet


WASHINGTON -- NASA's Phoenix Mars Lander has ceased communications after operating for more than five months. As anticipated, seasonal decline in sunshine at the robot's arctic landing site is not providing enough sunlight for the solar arrays to collect the power necessary to charge batteries that operate the lander's instruments.

Mission engineers last received a signal from the lander on Nov. 2. Phoenix, in addition to shorter daylight, has encountered a dustier sky, more clouds and colder temperatures as the northern Mars summer approaches autumn. The mission exceeded its planned operational life of three months to conduct and return science data.

The project team will be listening carefully during the next few weeks to hear if Phoenix revives and phones home. However, engineers now believe that is unlikely because of the worsening weather conditions on Mars. While the spacecraft's work has ended, the analysis of data from the instruments is in its earliest stages.

"Phoenix has given us some surprises, and I'm confident we will be pulling more gems from this trove of data for years to come," said Phoenix Principal Investigator Peter Smith of the University of Arizona in Tucson.

Launched Aug. 4, 2007, Phoenix landed May 25, 2008, farther north than any previous spacecraft to land on the Martian surface. The lander dug, scooped, baked, sniffed and tasted the Red Planet's soil. Among early results, it verified the presence of water-ice in the Martian subsurface, which NASA's Mars Odyssey orbiter first detected remotely in 2002. Phoenix's cameras also returned more than 25,000 pictures from sweeping vistas to near the atomic level using the first atomic force microscope ever used outside Earth.

"Phoenix not only met the tremendous challenge of landing safely, it accomplished scientific investigations on 149 of its 152 Martian days as a result of dedicated work by a talented team," said Phoenix Project Manager Barry Goldstein at NASA's Jet Propulsion Laboratory in Pasadena, Calif.

Phoenix's preliminary science accomplishments advance the goal of studying whether the Martian arctic environment has ever been favorable for microbes. Additional findings include documenting a mildly alkaline soil environment unlike any found by earlier Mars missions; finding small concentrations of salts that could be nutrients for life; discovering perchlorate salt, which has implications for ice and soil properties; and finding calcium carbonate, a marker of effects of liquid water.

Phoenix findings also support the goal of learning the history of water on Mars. These findings include excavating soil above the ice table, revealing at least two distinct types of ice deposits; observing snow descending from clouds; providing a mission-long weather record, with data on temperature, pressure, humidity and wind; observations of haze, clouds, frost and whirlwinds; and coordinating with NASA's Mars Reconnaissance Orbiter to perform simultaneous ground and orbital observations of Martian weather.

"Phoenix provided an important step to spur the hope that we can show Mars was once habitable and possibly supported life," said Doug McCuistion, director of the Mars Exploration Program at NASA Headquarters in Washington. "Phoenix was supported by orbiting NASA spacecraft providing communications relay while producing their own fascinating science. With the upcoming launch of the Mars Science Laboratory, the Mars Program never sleeps."

The University of Arizona leads the Phoenix mission with project management at JPL and development partnership at Lockheed Martin Corporation in Denver. International contributions came from the Canadian Space Agency; the University of Neuchatel, Switzerland; the universities of Copenhagen and Aarhus in Denmark; the Max Planck Institute in Germany; the Finnish Meteorological Institute; and Imperial College of London.

For additional information about Phoenix mission findings, visit:

http://www.nasa.gov/phoenix