Washington - A blanket of icy clouds may have kept ancient Mars warm enough to let water flow on its surface, and may have encouraged life in its caves and oceans, scientists in Paris and Chicago reported yesterday. Since the 1970s, astronomers have seen channels on Mars that they thought to be the remnants of flowing liquid water, but they were puzzled as to how the water got warm enough to flow.
Now researchers at the University of Chicago and the Laboratoire de Meteorologie Dynamique du CNRS in Paris believe that a thick layer of icy carbon dioxide clouds warmed Mars through a kind of Martian greenhouse effect.