蔣紹南

美國宇航局25日宣布，當?shù)貢r間25日晚，美國“鳳凰”號火星著陸探測器成功降落在火星北極附近區(qū)域?！傍P凰號”此行的任務是尋找水和其它支持生命所需化學物質(zhì)的證據(jù)。

A three-legged NASA spacecraft was closing in on Mars yesterday for what scientists hope will be the first-ever touchdown near Mars north pole to study whether the permafrost could have supported primitive life.

The time it takes the Phoenix Mars Lander to streak through the atmosphere and set down on the dusty surface has been dubbed “the seven minutes of terror” for good reason.More than half of the worlds attempts to land on Mars have ended in failures.

“Im a little nervous on the inside.Im getting butterflies，” Peter Smith，principal investigator from the University of Arizona，Tucson，said on the eve of the landing.“We bet the whole farm on this safe landing and we cant do our science without this safe landing.”

Phoenix is preprogrammed to plummet through the Red Planets atmosphere，and will rely on the intricately choreographed use of its heat shield，parachute and rockets to slow its descent from over 19，300 kph to a 8 kph touchdown.

In the ideal scenario，“we evolve out of this cocoon and spread our wings and we turn into this beautiful butterfly on the surface，”said Ed Sedivy，program manager at Lockheed Martin Corp，which built Phoenix.

Mission controllers decided late Saturday to skip an opportunity to adjust Phoenixs flight path since the lander was well on track for its target landing site.

NASA has not had a successful soft landing in more than three decades since the twin Viking landers in 1976.The last time the space agency tried was in 1999 when the Mars Polar Lander angling for the south pole crashed after prematurely cutting off its engines.

Phoenix was built from a lander that was scrapped after the Polar Lander disaster.Engineers spent years testing Phoenix to resolve all known problems，but there are no guarantees on landing day.

Launched last summer，Phoenix has traveled 679 million km over nearly 10 months.Its arrival to the high northern latitudes will be closely watched by a trio of Mars orbiters circling overhead.If successful，it will join the twin Mars rovers，Spirit and Opportunity，which have been exploring the equatorial plains since 2004.

The $420 million mission is led by the University of Arizona and managed by JPL.

美國國家航空航天局一艘有三條腿的太空飛船昨日抵達火星附近，科學家期待，這將是人類首次抵達火星北極附近，對那里的永久冰凍帶是否能維持原始生命進行研究。

“鳳凰”號火星登錄探測器要飛速穿越大氣層，然后降落在滿是灰塵的火星表面，這期間所花的時間被稱為“恐怖七分鐘”，這樣說不無道理。因為世界上登錄火星的嘗試多半都以失敗告終。

“我內(nèi)心深處有點緊張，神經(jīng)質(zhì)地在發(fā)抖，”來自塔克森市亞利桑那大學的首席研究員彼得·史密斯在火星成功登陸前夕說道?！盀檫@次安全著陸，我們把整個農(nóng)場都拿來做賭注了，如果無法安全著陸，以后就無法研究下去了。”

鳳凰號預定從這個紅色的行星大氣層垂直降落，并要依賴精心設(shè)計的熱擋板、降落傘和火箭來把降落速度從每小時19，300 千米減到每小時8千米。

理想情況下，“我們就能夠破繭化蝶，伸展雙翼，在火星表面化身美麗的蝴蝶，” 建造“鳳凰”號探測器的洛克希德·馬丁公司項目主管埃德·塞迪威說。

該任務的控制人員周六晚些時候決定不再調(diào)整鳳凰的飛行路徑，因為登陸探測器已經(jīng)準備好朝目標著陸點降落。

這是自1976年美國國家航空航天局孿生姐妹“海盜”號登陸器嘗試登陸火星以來的30多年第一次實現(xiàn)軟著陸。航天局上次進行火星著陸嘗試的時間是1999年，當時，火星極地登陸探測器在靠近南極時，因過早關(guān)閉發(fā)動機而墜毀。

“鳳凰”號的建造基于極地登陸災難發(fā)生后用拆卸部件組裝的登陸器。工程師花了幾年時間測試鳳凰的性能，以解決所有已知問題，但這并不能擔保那天能安全著陸。

去年夏天發(fā)射的鳳凰號行程已達679，000，000千米，時間長達近10個月。它將抵達火星北部高緯度地區(qū)，這一過程會由繞其上飛行的三個火星衛(wèi)星嚴密監(jiān)視。如果成功，它將加入孿生姐妹火星漫游器“勇氣”號和“機遇”號的行列，后兩者從2004年就開始進行火星赤道平原的探測工作了。

這項花費4.2億美元的項目是由亞利桑那州大學領(lǐng)導，美國噴氣推進所實驗管理的?！?/p>