NASA's Phoenix spacecraft has discovered two minerals on Mars that suggest water was there in the past.
Scientists reported Monday that the minerals — carbon carbonate and sheet silicate — don't usually form without the presence of liquid water.
Phoenix landed in the Martian arctic plains in May on a three-month mission to study whether the environment could be friendly to microbial life. One of its main goals is to probe whether the ice ever melted.
NASA recently extended the mission through the end of the year, depending on whether Phoenix can survive that long.