Europe's Mars orbiter has found the most direct evidence yet of water in the form of ice on the Red Planet's surface, the European Space Agency said Friday.
While scientists have long believed that the planet's polar caps contain frozen water, the findings were based on indirect methods such as analysis of temperature data or the detection of traces of hydrogen.
European scientists said their discovery was based on analysis of vapors of water molecules detected by the infrared camera aboard the Mars Express (search) spacecraft that is circling the Red Planet's south pole.
"You look at the picture, look at the fingerprint and say this is water ice," said Allen Moorehouse, the project's manager of spacecraft operations. "This is the first time it's been detected on the ground. This is the first direct confirmation."
If Mars once had surface water, it had the potential to support life — although Moorehouse cautioned that it was too early to draw conclusions.
In 2001, NASA's Mars Odyssey (search) spacecraft had determined that there is lots of ice mixed with the soil, as little as 18 inches from the surface.
However, ESA's science director David Southwood said those previous conclusions were based on indirect measurements, such as the detection of traces of hydrogen, and that the European finding was more concrete.
"Previous measurements have been indirect and this is the first time we have direct indications of molecules that are present in water," Southwood said. "Of course, finding anything that has to do with water on Mars is a sort of holy grail. This is certainly better than anything we've had so far."
However, the director of NASA's Mars exploration program disputed the Europeans' claim that their discovery was new.
"Our Odyssey spacecraft that has been orbiting Mars since 2001 did discover vast amounts of frozen water in the northern and southern latitudes. And we were surprised by the fact that there was so much, and so close to the surface," Orlando Figueroa, director of NASA's Mars exploration program, told CNN on Friday.
"So it's not new news but we are happy to see that their satellite is also able to pick up where it exists," he said when asked about the Mars Express findings
Phil Christensen, an Arizona State University (search) professor involved in NASA's Mars projects, said the findings bolstered known data that pointed to the presence of frozen water on Mars.
"That is a very nice confirmation of the other measurements that have been previously made," he told The Associated Press.
European Space Agency (search) officials said their discovery confirmed something that scientists long suspected.
"It's been looked at for such a long time and it's been inferred there was water" at the south pole, said agency scientist Jean-Pierre Bibring.
"This is the first time we can really see vapors of the molecules themselves," he said.
More than 40 years of Mars exploration have been searching for evidence of whether the planet ever had liquid water.
Mars Odyssey, as well as another U.S. spacecraft, Mars Global Surveyor (search), have been circling the planet searching for indications of water.
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 Mars Express orbiter is part of Europe's first mission to Mars. Mars Express hit orbit Dec. 25 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. Its companion Beagle 2 lander, released toward the surface Dec. 19, hasn't been heard from since its own scheduled landing on Dec. 25.
NASA has also run into trouble with contacting its Spirit rover this week, but NASA engineers got a 10-minute signal Friday and planned further communications with it in an effort to diagnose and possibly patch up their ailing robotic patients on Mars.