California ? A spacecraft orbiting Mars has spotted water ice in several impact craters midway between the north pole and equator — the first time ice so close to the surface has been discovered so far south on the red planet.

Instruments on NASA’s Mars Reconnaissance Orbiter estimated that the newfound ice is 99 percent pure.

Previous spacecraft have spied ice lurking below the Martian surface. Before the Phoenix lander froze to death last year, it dug trenches and touched ice specks at its arctic landing site.

Last year, radar observations from the Reconnaissance Orbiter pointed to the presence of buried glaciers in the Martian mid-latitudes. The latest discovery came as a surprise because scientists did not expect to find shallow ice this far south.

The findings will be published in today’s issue of the journal Science.

This means “the recent climate of Mars was wetter than what we see today,” said lead author Shane Byrne, an associate professor of planetary science at the University of Arizona.