Phoenix lander spots falling snow on Mars CNN

NASA’s Phoenix spacecraft has discovered evidence of past water at its Martian landing site and spotted falling snow for the first time, scientists reported Monday. Soil experiments revealed the presence of two minerals known to be formed in liquid water. Scientists identified the minerals as calcium carbonate, found in limestone and chalk, and sheet silicate.
But exactly how that happened remains a mystery.
“It’s really kind of all up in the air,” said William Boynton, a mission scientist at the University of Arizona at Tucson.
A laser aboard the Phoenix recently detected snow falling from clouds more than two miles above its home in the northern arctic plains. The snow disappeared before reaching the ground.