The spacecraft named Mars Odyssey has settled into its working orbit and started sending back pictures of the red planet. This photo shows the highly fractured, faulted and deformed Acheron Fossae region of Mars.

Odyssey, which began mapping the Martian surface last week, used a suite of gamma ray spectrometer instruments to detect significant amounts of hydrogen near the planet's south pole, which scientists said are most likely due to the presence of ice formed from water.

"We're not looking at just surface frost, there's really a lot of ice," said William Boynton, professor at the University of Arizona's Lunar and Planetary Laboratory said during a press conference at NASA's Jet Propulsion Laboratory.

Earlier missions to Mars by NASA's Viking Orbiter and Global Surveyor spacecraft have previously suggested that ice might be found on the red planet and scientists have concluded that water once flowed there, creating deep canyons and other geologic features that can still be seen.

But the findings by Odyssey, which was launched in April of 2001 and arrived in Mars orbit in October, could provide the first real proof of ice still formed on the surface.

"We're delighted with the quality of the data we're seeing," Stephen Saunders, Odyssey project scientist, said. "We'll use it to build on what we've learned from Mars Global Surveyor and other missions. Now we may actually see water rather than guessing where it is or was."

Scientists said preliminary assessment of the data suggest the presence of hydrogen in the upper few feet of the Martian surface in an area about 400 miles (644 km) across.

"If you were an astronaut walking around on the surface of Mars you could kick the ground and see ice crystals," Boynton said. "You could melt it and have water."

Boynton said scientists were excited about the discovery because the presence of water ice suggests water, and water suggests life on Mars.

"It's really because we need to understand what happened to all the water that made these canyons and where that water went," he said. "We want to understand the climate of the planet and its changes."

Boynton said scientists have several theories to explain what happened to the water that once flowed on Mars, with most believing that the planet was formerly much warmer.

"Mars is really a very, very rich environment," he said. "It's not the dead planet that we might have been taught that it was in high school."