BioZine

A large number of the valley networks scarring Mars's surface were carved by water melting beneath glacial ice, not by free-flowing rivers as previously thought, according to new research. The findings effectively throw cold water on the dominant 'warm and wet ancient Mars' hypothesis, which postulates that rivers, rainfall and oceans once existed on the red planet.

Two NASA astronauts splashed down safely in the Gulf of Mexico Sunday for the first time in a commercially built and operated American crew spacecraft, returning from the International Space Station to complete a test flight that marks a new era in human spaceflight.