Reservoirs of Ice, but No Water, Found Deep Within Mars

Using sophisticated radar aboard the European Mars Express spacecraft, scientists have for the first time peered into the heart of Mars, uncovering ancient geological structures and reservoirs of ice more than a mile beneath the arid surface.

“We’re looking at the third dimension on Mars, something no other mission has done before,” Agustin Chicarro, project scientist for the European Space Agency, said during a news conference Wednesday from the agency’s Paris headquarters.

Chicarro said instruments aboard the spacecraft, which has been orbiting Mars since December 2003, had revealed what looked like an ancient impact basin in the temperate region and fresh stores of ice near the north pole.

But the craft’s radar, known as the Mars Advanced Radar for Subsurface and Ionospheric Sounding, did not uncover any evidence of liquid water underground.

“We certainly can say we observed a significant amount of subsurface water in the form of ice,” said team member Jeffrey Plaut of NASA’s Jet Propulsion Laboratory. “But there’s no current evidence yet for subsurface liquid water.”

The question of liquid water on Mars is key to determining whether some form of rudimentary life could have, or still might, exist on Mars.

Though the Martian surface is too inhospitable to support life as we know it, scientists have speculated that rudimentary life forms could exist in relatively warm, subsurface pools.

In the north pole scan, scientists were able to penetrate through about a mile of ice to subsurface soils, the boundary region where a pool might form. But polar temperatures plunge to minus 200 degrees Fahrenheit, too cold for any melting, even at great depths, and much too cold for any kind of life similar to that on Earth.

But in the more temperate mid-latitudes, “you don’t have to go too deep to have temperatures that would allow liquid,” Plaut said in a telephone interview from Paris.

The team’s findings were presented in series of papers released this week by the journals Science and Nature.

Plaut emphasized that Mars Express was just beginning to scout the interior of Mars.

In the next year, controllers on Earth will be looking for the radar signature of liquid water in the temperate areas, where the atmospheric temperature can rise to 32 degrees.

Other instruments aboard the spacecraft, sent into space aboard a Soyuz launcher from Baikonur, Kazakhstan, in June 2003, filled in the portrait of an ancient Mars, depicting a planet that appears much less friendly to life than previously thought. The conventional wisdom has been that Mars in ancient times was warmer and wetter, and that some climate change caused the planet to lose its surface water.

“We may have to revise some of our early views,” said Gerhard Neukem, the investigator on the craft’s high-resolution stereo camera. “It wasn’t so warm and it wasn’t so wet.”

Early on, water flowed on the surface. It even plunged over gigantic waterfalls into deep basins, he said. But according to the scientific team, the planet fell dry about 3.5 billion years ago.

“There was a very dramatic climate change from an early cold and wet planet to a colder and drier one,” Chicarro said.