Europe's Mars orbiter has detected evidence of ice water on the planet, scientists at the European Space Agency announced today.
Mars Express, circling high above the surface, made the discovery on the Red Planet's south pole, said agency scientist Jean-Pierre Bibring - an indication that Mars may once have sustained life.
"We have been tracking it on the south pole and there we have detected water, probably for the first time," Bibring said in Germany.
More than 40 years of Mars exploration have yielded inconclusive evidence of whether water was present on the planet.
Two US orbiters, Mars Global Surveyor and the 2001 Mars Odyssey, have also been circling the planet searching for indications of water in the Martian past.
In October, a team of scientists reported Odyssey had detected on the surface of Mars copious amounts of a mineral that's easily weathered away in the presence of water. That suggested Mars has been a dry wasteland.
Weeks later, a second team reported evidence to the contrary after Global Surveyor beamed back images that show features apparently created by the meandering flow of rivers.
The European Space Agency's Mars Express orbiter is part of Europe's first mission to Mars. Mars Express hit orbit on Christmas Day and began transmitting its first data from the planet this month, starting with high-resolution pictures of the surface that captured in detail a huge Martian canyon.
The latest discovery was made by a device aboard the orbiter, a spectrometer, that is mapping the surface's mineral composition, Bibring said at mission control in Darmstadt.