火星曾是水世界

The Red Plant's Watery Past

探测车和轨道船的新发现显示,火星上不仅存在液态水,而且覆盖大部分星球表面长达10亿年之久。

New observations by rovers and orbiters1 indicate that liquid water not only existed on Mars,it once covered large parts of the planet's surface,perhaps for more than a billion years.