登陸火星--"恐怖7分鐘"

美國宇航局的"好奇號"探測器將於8月5日登陸火星。是成功，還是撞毀或燒毀，取決於短短的7分鐘。

https://p.dw.com/p/15hGD

Curiosity - The Next Mars Rover This artist concept features NASA's Mars Science Laboratory Curiosity rover, a mobile robot for investigating Mars' past or present ability to sustain microbial life. Curiosity is being tested in preparation for launch in the fall of 2011. In this picture, the rover examines a rock on Mars with a set of tools at the end of the rover's arm, which extends about 2 meters (7 feet). Two instruments on the arm can study rocks up close. Also, a drill can collect sample material from inside of rocks and a scoop can pick up samples of soil. The arm can sieve the samples and deliver fine powder to instruments inside the rover for thorough analysis. The mast, or rover's "head," rises to about 2.1 meters (6.9 feet) above ground level, about as tall as a basketball player. This mast supports two remote-sensing instruments: the Mast Camera, or "eyes," for stereo color viewing of surrounding terrain and material collected by the arm; and, the ChemCam instrument, which is a laser that vaporizes material from rocks up to about 9 meters (30 feet) away and determines what elements the rocks are made of. NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology, Pasadena, manages the Mars Science Laboratory Project for the NASA Science Mission Directorate, Washington. For more information about Curiosity is at http://mars.jpl.nasa.gov/msl/ . Image credit: NASA/JPL-Caltech — 圖片來源： NASA/JPL-Caltech

（德國之聲中文網）美國宇航局的火星科學研究室--又稱"好奇號"（Curiosity）探測器進入火星大氣層時將面臨嚴峻的7分鐘。在7分鐘內，它必須從1.3萬英裡（2.1萬公里）的時速減速至零。這生死攸關的時段被稱為恐怖7分鐘。

預計8月5日晚（太平洋時區，歐洲時區為8月6日早晨）"好奇號"將登陸。不過，訊號從"好奇號"傳遞至地球需要14分鐘，是登陸時間的兩倍。所以，當美國宇航局得到訊號時，"好奇號"已經著陸7分鐘了，--無論是生是死。

"盲登"

這次登陸也被稱為"盲登"，因為美國宇航局所依賴的衛星出了故障。但火星探索項目的負責人麥克-丘斯宸（Doug McCuistion）說，這對登陸本身並沒有影響，只是數據收集的時效性受到影響。在美國宇航局的請求下，歐洲宇航局的探測衛星"火星快車號"（Mars Express）將觀測登陸。自2003年12月起，"火星快車號"一直在火星軌道上，當時"獵犬2號"（Beagle 2）火星探測器登陸失敗。

"火星快車號"行動負責人丹尼斯（Michel Denis）說，歐洲宇航局將為美國宇航局自身的追蹤系統提供備份支持，以防萬一。"對宇航科學來說，這將是偉大的一天。"丹尼斯相信"好奇號"將成功登陸，儘管他也承認在宇航項目中沒有保證一說。

Testing during March and April 2009 inside the world's largest wind tunnel, at NASA Ames Research Center, Moffett Field, Calif., qualified the parachute for NASA's next Mars rover. The parachute for NASA's Mars Science Laboratory mission, to be launched in 2011 and land on Mars in 2012, is the largest ever built to fly on an extraterrestrial mission. This image shows the qualification-test parachute beginning to open a few seconds after it was launched from a mortar into an 80-mile-per-hour (36-meter-per-second) wind. The parachute uses a configuration called disk-gap-band. It has 80 suspension lines, measures more than 50 meters (165 feet) in length, and opens to a diameter of nearly 16 meters (51 feet). Most of the orange and white fabric is nylon, though a small disk of heavier polyester is used near the vent in the apex of the canopy due to higher stresses there. Pioneer Aerospace, South Windsor, Conn., built the parachutes for testing and for flying on the Mars Science Laboratory. The wind tunnel used for the testing is part of the National Full-Scale Aerodynamics Complex, operated by the Arnold Engineering Development Center of the U.S. Air Force. NASA's Jet Propulsion Laboratory, Pasadena, Calif., is building and testing the Mars Science Laboratory spacecraft for the NASA Science Mission Directorate, Washington. JPL is a division of the California Institute of Technology. Image Credit: NASA/JPL-Caltech — 美國宇航局基地的模擬測試圖片來源： NASA/JPL-Caltech

落地後即可運行

"好奇號"登陸時必須完成一系列高度複雜的操作，由探測器上的電腦控制完成。首先，火星大氣層將幫助"好奇號"時速減緩1.2萬英裡。火星的大氣層比地球稀薄100倍。其次，探測器將釋放出一個降落傘，降落傘可承受6.5萬磅的力量。探測器的熱護盾在370英裡時速時脫落，降落傘也將脫離，屆時，制動火箭系統將激活。

時速從70英裡減至2英裡後，探測器將在"天空起重機"（sky crane）這一軟著陸緩沖系統的幫助下，從25英呎（7.62米）的高度降落至火星地表。

歐洲宇航局的丹尼斯認為，"好奇號"一旦成功著陸，就可進入運行狀態，"它會像一輛新買的車一樣"。

Curiosity's Sky Crane Maneuver, Artist's Concept This artist's concept shows the sky crane maneuver during the descent of NASA's Curiosity rover to the Martian surface. The entry, descent, and landing (EDL) phase of the Mars Science Laboratory mission begins when the spacecraft reaches the Martian atmosphere, about 81 miles (131 kilometers) above the surface of the Gale crater landing area, and ends with the rover Curiosity safe and sound on the surface of Mars. Entry, descent, and landing for the Mars Science Laboratory mission will include a combination of technologies inherited from past NASA Mars missions, as well as exciting new technologies. Instead of the familiar airbag landing systems of the past Mars missions, Mars Science Laboratory will use a guided entry and a sky crane touchdown system to land the hyper-capable, massive rover. The sheer size of the Mars Science Laboratory rover (over one ton, or 900 kilograms) would preclude it from taking advantage of an airbag-assisted landing. Instead, the Mars Science Laboratory will use the sky crane touchdown system, which will be capable of delivering a much larger rover onto the surface. It will place the rover on its wheels, ready to begin its mission after thorough post-landing checkouts. The new entry, descent and landing architecture, with its use of guided entry, will allow for more precision. Where the Mars Exploration Rovers could have landed anywhere within their respective 93-mile by 12-mile (150 by 20 kilometer) landing ellipses, Mars Science Laboratory will land within a 12-mile (20-kilometer) ellipse! This high-precision delivery will open up more areas of Mars for exploration and potentially allow scientists to roam "virtually" where they have not been able to before. In the depicted scene, the spacecraft's descent stage, while controlling its own rate of descent with four of its eight throttle-controllable rocket engines, has begun lowering Curiosity on a bridle. The rover is connected to the descent stage by three nylon tethers and by an umbilical providing a power and communication connection. The bridle will extend to full length, about 25 feet (7.5 meters), as the descent stage continues descending. Seconds later, when touchdown is detected, the bridle is cut at the rover end, and the descent stage flies off to stay clear of the landing site. The Mars Science Laboratory spacecraft is being prepared for launch during Nov. 25 to Dec. 18, 2011. Landing on Mars is in early August 2012. In a prime mission lasting one Martian year (nearly two Earth years) researchers will use the rover's tools to study whether the landing region has had environmental conditions favorable for supporting microbial life and for preserving clues about whether life existed. NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology, Pasadena, Calif., manages the Mars Science Laboratory Project for the NASA Science Mission Directorate, Washington. More information about Curiosity is at http://www.nasa.gov/msl and http://mars.jpl.nasa.gov/msl/ . Image credit: NASA/JPL-Caltech — 「天空起重機」操作圖片來源： NASA/JPL-Caltech

大小很重要

"好奇號"探測器與一輛運動型多功能車（SUV）大小相似，7英呎高，9英呎寬，10英呎長，2000磅重。"好奇號"是目前最大、設備最齊全的外星探測器。

與"好奇號"相比，1997年首次登陸的"索傑納號"（Sojourner）火星車則形同侏儒，後者只有23磅重。2004年登陸的"勇氣號"和"機遇號"火星探測器為400磅重。

此外，"好奇號"的時速也比"機遇號"的最高時速超出0.1英裡，為3.35英裡。

速度並非一切，生存下來最重要。"機遇號"仍在繼續探測一個命名為"奮力"（Endeavour）的大型撞擊坑。它已行進21.4英裡，仍在發送寶貴的數據。

Curiosity Touching Down, Artist's Concept This artist's concept depicts the moment that NASA's Curiosity rover touches down onto the Martian surface. The entry, descent, and landing (EDL) phase of the Mars Science Laboratory mission begins when the spacecraft reaches the Martian atmosphere, about 81 miles (131 kilometers) above the surface of the Gale crater landing area, and ends with the rover safe and sound on the surface of Mars. Entry, descent, and landing for the Mars Science Laboratory mission will include a combination of technologies inherited from past NASA Mars missions, as well as exciting new technologies. Instead of the familiar airbag landing systems of the past Mars missions, Mars Science Laboratory will use a guided entry and a sky crane touchdown system to land the hyper-capable, massive rover. The sheer size of the Mars Science Laboratory rover (over one ton, or 900 kilograms) would preclude it from taking advantage of an airbag-assisted landing. Instead, the Mars Science Laboratory will use the sky crane touchdown system, which will be capable of delivering a much larger rover onto the surface. It will place the rover on its wheels, ready to begin its mission after thorough post-landing checkouts. The new entry, descent and landing architecture, with its use of guided entry, will allow for more precision. Where the Mars Exploration Rovers could have landed anywhere within their respective 93-mile by 12-mile (150 by 20 kilometer) landing ellipses, Mars Science Laboratory will land within a 12-mile (20-kilometer) ellipse! This high-precision delivery will open up more areas of Mars for exploration and potentially allow scientists to roam "virtually" where they have not been able to before. In the depicted scene, Curiosity is touching down onto the surface, suspended on a bridle beneath the spacecraft's descent stage as that stage controls the rate of descent with four of its eight throttle-controllable rocket engines. The rover is connected to the descent stage by three nylon tethers and by an umbilical providing a power and communication connection. When touchdown is detected, the bridle will be cut at the rover end, and the descent stage flies off to stay clear of the landing site. The Mars Science Laboratory spacecraft is being prepared for launch during Nov. 25 to Dec. 18, 2011. Landing on Mars is in early August 2012. In a prime mission lasting one Martian year (nearly two Earth years) researchers will use the rover's tools to study whether the landing region has had environmental conditions favorable for supporting microbial life and for preserving clues about whether life existed. NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology, Pasadena, Calif., manages the Mars Science Laboratory Project for the NASA Science Mission Directorate, Washington. More information about Curiosity is at http://www.nasa.gov/msl and http://mars.jpl.nasa.gov/msl/ . Image credit: NASA/JPL-Caltech — 模擬登陸圖圖片來源： NASA/JPL-Caltech

可能是最後一次登陸

25億美元（21億歐元）的價格也使得"好奇號"成為美國宇航局最昂貴的火星探測器。由於預算高達10億美元，這恐怕也是美國宇航局在可預見的未來最後一次火星登陸使命。

這一為期兩年的使命任務是探索"蓋爾"撞擊坑（Gale Crater）,它位於火星赤道附近，再就是搜尋生命跡象。

"好奇號"有著相應的裝備。六輪探測器可以向岩石發射雷射，測量其化學組成，拍攝高清晰的火星地貌影片。

探測器配備有感測器、攝影機，有一支長長的機械手臂，有一個鏟子可以收集土壤樣品，一個鑽頭可以鑽入岩石，一個高敏感度的鏡頭可以檢測12.5微米的微觀結構。

歐洲宇航政策研究所（ESPI）的胡斯羅伊（Peter Hulsroj）說："火星探測使命有助於宇航事業的整體發展。'好奇號'邁出美妙的一步。"

自1960年以來，美國、歐洲、俄羅斯、日本先後啟動40次火星使命，然而，超過一半撞毀、運作不靈或者失去蹤跡。

Context of Curiosity Landing Site in Gale Crater This oblique, southward-looking view of Gale crater shows the mound of layered rocks that NASA's Mars Science Laboratory will investigate. The mission's selected landing site is just north of the mound inside the crater. Gale crater is 96 miles (154 kilometers) in diameter and holds a layered mountain rising about 3 miles (5 kilometers) above the crater floor. The landing site contains material washed down from the wall of the crater, which will provide scientists with the opportunity to investigate the rocks that form the bedrock in this area. The landing ellipse also contains a rock type that is very dense and very bright colored; it is unlike any rock type previously investigated on Mars. It may be an ancient playa lake deposit, and it will likely be the mission's first target in checking for the presence of organic molecules. The area of top scientific interest for Mars Science Laboratory is at the base of the mound, just at the edge of the landing ellipse. Here, orbiting instruments have detected signatures of both clay minerals and sulfate salts. Scientists studying Mars have several important hypotheses about how these minerals reflect changes in the Martian environment, particularly changes in the amount of water on the surface of Mars. The Mars Science Laboratory rover, Curiosity, will use its full instrument suite to study these minerals and how they formed to give us insights into those ancient Martian environments. These rocks are also a prime target in checking for organic molecules. This three-dimensional perspective view was created using visible-light imaging by the Thermal Emission Imaging System camera on NASA's Mars Odyssey orbiter. Three-dimensional information was derived from observations by the Mars Orbiter Laser Altimeter, which flew on NASA's Mars Global Surveyor orbiter. Color information is derived from color imaging of portions of the scene by the High Resolution Imaging Science Experiment camera on NASA's Mars Reconnaissance Orbiter. The vertical dimension is not exaggerated. The Mars Science Laboratory spacecraft is being prepared for launch during the period Nov. 25 to Dec. 18, 2011. In a prime mission lasting one Martian year -- nearly two Earth years -- after landing, researchers will use the rover's tools to study whether the landing region has had environmental conditions favorable for supporting microbial life and for preserving clues about whether life existed. NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Mars Science Laboratory Project for NASA's Science Mission Directorate in Washington. Arizona State University, Tempe, operates the Thermal Emission Imaging System. The Mars Orbiter Laser Altimeter was operated by NASA Goddard Space Flight Center, Greenbelt, Md. The University of Arizona, Tucson, operates the High Resolution Science Imaging Experiment. JPL manages Mars Odyssey and Mars Reconnaissance Orbiter for NASA's Science Mission Directorate. Image Credit: NASA/JPL-Caltech/ASU/UA — "蓋爾」撞擊坑圖片來源： NASA/JPL-Caltech/ASU/UA

作者：John Blau / Holly Cooper 編譯：苗子

責編：謝菲

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