Phoenix has arrived on Mars, in search of places where life might exist. But an analysis of the planet's rocks suggests that there is probably none to look for
带着寻找生命任务的凤凰号已经在火星着陆。但在对星球演示的分析中指出寻找生命的希望可能落空。
THE past few days have brought good news and bad for those who hope to find Martians of some description or other. The good news is that on May 25th Phoenix, America's latest mission to Mars, landed successfully where many others have failed. The bad is that an analysis of the results of previous successful missions suggests it is unlikely that life ever got going there in the first place, let alone survived the transition to the harsh Martian conditions prevailing today. The balmy, watery past conjured up in the minds of the eternal optimists who inhabit the exobiology departments of the Earth's universities has been replaced by something more akin to a planet-sized version of the Dead Sea.
To start with the positive, though, Phoenix's landing seems to have been picture-perfect. Literally. The photograph above, which was taken from a spacecraft called Mars Reconnaissance Orbiter during Phoenix's descent, shows how it first deployed a parachute to slow itself. It then, in classic sci-fi fashion, fired retro-rockets to make a controlled touch-down on three spindly legs, rather than swaddling itself wimpishly in balloons and bouncing around for a bit before settling, as some previous missions have done.
不过，凤凰号的着陆确实是完美的，这是一个积极的开始。这一点毫不夸张。火星侦查员号探测器在凤凰号降落的途中拍摄的照片显示它是如何首先打开降落伞，然后如同经典的科幻小说一般，点燃后进推动火箭是控制器用三只细长的脚着陆，而不是如同之前的探测任务中那样将它自己束缚在一个大球中，弹跳着着陆。
More pleasingly still, the first images it sent back could have come out of a geography textbook's chapter on arctic terrain. They show a surface broken into polygonal slabs by repeated freezing and thawing of the sort that happens above permafrost. For, unlike any previous successful mission to Mars, Phoenix has landed not in the planet's tropics but near one of its poles. And the reason for going there is the same as the reason for the polygonal slabs. It is that the Martian poles are repositories of ice, and the hunt for water on Mars has now become almost obsessive.
更加高兴的是，在其发回的第一个图片中的影像仿佛就像是来自地理书中北极圈图片一样。它显示了其在永久冰冻区之上的表面由于多次冰冻和融化已经成为多边形的冰板。并不像先前成功着陆与火星的探测器，凤凰号并没有着陆与星球的热带，而是靠近其中一个极点。而这次着陆不同于之前的原因与探测多边形冰板一样，只在火星极点附近才有可能存有冰，而在火星上获取水源如今变得十分必要。
