火星上的“鳳凰”的生命已經終結

NASA於十一月十日正式宣布：於今年五月下旬登陸火星的探測器“鳳凰”（Phoenix），經過五個月的緊張探測工作後，順利完成了科學家們賦予它的使命，它的生命已經終結。

鳳凰號原定的設計壽命是三個月，它已超期服役了兩個月。

Phoenix 的主要任務是探測火星北極附近是否有水，所以，它的著陸地方離北極很近。現在，火星的北半球和地球北半球是一樣的，進入冬季。太陽的光線照射角度很低。探測器又遭遇塵暴。它的太陽能板無法給電池充上足夠的電力。科學家們最後一次收到它的信號是十一月五號。所以，宣布它的壽命已終結。

不過，在未來幾周內，科學家們還會細心地傾聽能否從火星還發來信號。估計這種可能性很低了。因為探測器一旦被凍死，幾乎沒有再複活的機會。正常情況下，在火星的晚上，探測器停止工作，僅供少量的電力加熱關鍵部件，以免它被凍死。它無法活過火星北半球上的嚴酷冬季，不能像另兩個火星探測器已經在火星上工作了四年多，現在仍然在工作。它們是在火星的赤道附近。

鳳凰探測器的任務已完滿地完成了。它通過采樣化驗，發現火星上地表下很淺的地方就有水冰。並發現有雪從空中落下，當然是很稀少的量。


1，這是鳳凰探測器在火星表麵掘出的溝。圖片中的白色物，後來科學家們宣布是水冰。



2，這是鳳凰號拍攝的照片。為火星的早上，地上有白霜。


它發回地球的數據會被科學家們仔細地研究，也許會揭開許多秘密。火星上曾經有過許多地表水。現在則很少了。一個問題自然是，它的水怎樣消失的？科學家們會在未來的歲月裏來回答這個問題。一種可能是：火星的個頭相對地球是很小的，它內部的放射能早已耗盡。它在地質意義上講是死了。地表的水在被宇宙的高能射線分解，逃逸到太空去了。而它的火山活動的停止，不再為地表提供水的補充。因而，它的水就慢慢地幹涸了。

若地球上的火山完全停止噴發，不再把禁錮在地殼內的水釋放出來補充在高空被宇宙高能射線分解的水分子。地球上的海洋也會慢慢幹涸了，像今天的火星一樣。當然，這個過程很緩慢。下次，你若再看到火山噴發，不要咒罵它。因為它對維持地球上生命有很重要的作用。

我們應向鳳凰號表示敬意！

文中照片來源NASA 網站。

下麵是NASA 網站宣布鳳凰的任務完成的全文。



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