火星水含有防冻剂（图）   

新的化学分析显示：过去的火星水不易结冰。

Martian Water Had Antifreeze

If life exists elsewhere in our solar system, Mars is the likeliest location, say most planetary scientists. There's just one problem: The Red Planet may never have been warm enough to support the wet biosystems that grace Earth. But that doesn't mean water didn't flow there. New findings suggest that martian water contained so much salt that it served as antifreeze.	许多行星科学家们表示，如果说生命存在于我们太阳系的其他地方，那么火星是它们最有可能生存的地方。问题只有一个：这颗红色行星可能一直不够温暖，无法养育象地球上这样湿润的生物系统。但是，这并不意味着那里过去没有流淌的水。新发现表明，火星水曾经含有大量起着防冻剂作用的盐分。
The antifreeze idea comes from an analysis of martian rocks and mineral deposits. A team of scientists from NASA and two Spanish institutions poured over data collected by the rovers Spirit and Opportunity, along with the earlier landers Viking 1 and Pathfinder, at four sites on the martian surface. The results are remarkably consistent. At each of the locations, the same nine elements--silicon, iron, sulfur, magnesium, calcium, chlorine, sodium, potassium, and aluminum--constitute the bulk of the ingredients in the surface rocks. Chemical interactions with all of these elements can keep water from freezing at temperatures well below 0°C, the team reports tomorrow in Nature.	火星水含有防冻剂的观点来自一项对火星岩石和矿床的分析。来自美国国家航空航天管理局的一组科学家和两个西班牙的研究机构纷纷前来分析火星探测器所搜集的资料。这些探测器包括“勇气号”和“机遇号”，以及更早的火星着陆装置“海盗1号”和“探路者号”，它们从火星表面的四个地点搜集了资料。分析结果极为一致：在每个地点上，相同的9种元素——硅、铁、硫、镁、钙、氯、纳、钾和铝——构成了表面岩石的大多数成分。研究人员在明天出版的《自然》杂志上报道说：跟所有这些元素之间所发生的化学作用，可以使水在大大低于0摄氏度的情况下而不至于冻结。
Meanwhile, the team also ran climate models using martian temperature data. Those models show that the planet's atmosphere has always been too thin to support warmer-than-freezing temperatures. Yet satellite photos have shown ravines and features that look a lot like riverbeds and deltas on the martian surface, strongly suggesting that liquid water once flowed there. The only way to reconcile these two pieces of evidence, the team says, is to assume that water on Mars was very salty--as salty as that in the saltiest lakes on Earth--and thus would have resisted freezing. Eventually, as martian temperatures plunged to present-day levels, the water did freeze. In the planet's thin air, it then evaporated, leaving behind the telltale mineral deposits discovered by the four probes.	同时，研究小组还利用火星的气温数据进行了气候模拟。模拟结果显示，火星的大气一直以来都很稀薄，无法说明拥有高于冰点的温度。然而，卫星图像显示出火星表面拥有沟壑以及看起来非常类似于河床和三角洲的地貌，有力地说明了液态水一度流经那里。研究小组称，把两条证据协调起来的唯一办法就是：假设火星当时的水含盐量特别高，相当于地球上最咸的咸水湖的含盐量，这样就有可能抗拒冻结。最后，随着火星温度下降到目前的水平，火星水终于冻结了。当时，在拥有稀薄空气的地方，水则蒸发掉，留下可以作为证据的矿床，被四个火星探测器所发现。
The paper's analysis is "consistent with the mineral-rich view we're obtaining from the rovers and the orbiters," says planetary scientist James Bell of Cornell University, a member of the Mars rover scientific team. "It's very likely that salty solutions played a role in shaping the martian landscape," agrees planetary scientist Itay Halevy of Harvard University, though he notes there might be other explanations for the mineral deposits.	“该论文中的分析跟我们通过着陆探测器和轨道探测器所观察到的结果一致：火星表面富含矿物，”火星探测器科研小组成员之一、康奈尔大学行星科学家詹姆斯·贝尔说。“很可能盐溶液在塑造火星地形方面起到了一定的作用，”哈佛大学行星科学家伊泰·阿莱维对分析结果表示同意，尽管他指出对于矿床可能还会有其他的解释。