美国航空航天局研究水星的信使号飞船为水星阴影极地区藏有水冰的假设提供了有力证据。

设在波多黎各的阿雷西博（Arecibo ）射电望远镜所拍摄的水星北极地区雷达图像中的亮斑，可能是水冰。

现在，美国航空航天局（NASA）研究水星的“信使号”（Messenger ）飞船上的仪器仪表为长期以来的假说提供了强有力的支持，即该行星在其永远处于阴影之中的极地环形坑内藏有丰富的水冰和其他冰冻挥发性物质。

美国航空航天局位于加利福尼亚州帕萨迪纳（Pasadena）的喷气推进实验室（Jet Propulsion Laboratory ）科学家、《科学快讯》（Science Express）11月29日公布的三篇论文之一的作者马修•西格勒（Matthew Siegler）说：“水星离太阳如此之近，所以水冰本是人们最不会期待的东西。” “但是，由于水星很低的倾斜度，两极附近的环形坑内全年都处于阴影之中，冷得令人难以置信。”

科学家们数十年前即认为，水星的两极可能藏有水冰和其他冰冻挥发物。1991年，阿雷西博射电望远镜检测到水星的两极有亮斑，使这一设想得到极大的支持。许多亮斑与20世纪70年代美国航空航天局的“水手10号”（Mariner 10 ）飞船所绘制的强力撞击形成的环形坑位置图相对应。然而，由于水手号飞船在通过时，只看到了水星不到50％的部分，行星科学家一直没有获得可以与雷达图像进行比较的水星两极的完整图像。

2011年和今年早些时候“信使号”飞船拍摄的图像证实，水星南北两极的所有雷达亮斑都位于这个星球表面上的阴影区域内。科学家们说，这些发现与对水冰的假设相吻合。

欲了解该发现的详细信息，请参阅美国航空航天局新闻稿。

NASA’s Messenger spacecraft studying Mercury has provided compelling support for the hypothesis that the planet harbors abundant water ice within its permanently shadowed polar craters.

The bright spots in this radar image of the planet Mercury’s north polar region, taken by the Arecibo radio telescope in Puerto Rico, probably represent water ice.

Now, instruments aboard NASA’s Messenger spacecraft studying Mercury have provided compelling support for the long-held hypothesis that the planet harbors abundant water ice and other frozen volatile materials within its permanently shadowed polar craters.

“About the last thing you would expect on a planet so close to the sun is water ice,” said Matthew Siegler, a scientist at NASA’s Jet Propulsion Laboratory in Pasadena, California, and an author on one of three papers published November 29 in Science Express. “But due to Mercury’s low tilt, craters near the poles can remain in year-round shadow and be ridiculously cold.”

Scientists suggested decades ago there might be water ice and other frozen volatiles trapped at Mercury’s poles. The idea received a boost in 1991 when the Arecibo radio telescope detected radar-bright patches at Mercury’s poles. Many of these patches corresponded to the locations of large impact craters mapped by NASA’s Mariner 10 spacecraft in the 1970s. However, because Mariner saw less than 50 percent of the planet as it passed by, planetary scientists lacked a complete diagram of the poles to compare with the radar images.

Images taken from Messenger in 2011 and earlier this year confirmed all radar-bright features at Mercury’s north and south poles lie within shadowed regions on the planet’s surface. These findings are consistent with the water ice hypothesis, scientists said.

For more on the discovery, see the NASA press release.