PASADENA, Calif. A new image from NASAs Galileo spacecraft shows frigid scars left on the icy face of Jupiters moon Europa by the impact of a comet or asteroid.

In the false-color image of the ring-shaped crater, captured in 1998 but released this week, the brightest reds show areas of relatively pure frozen water, while the blues indicate the presence of other materials as well. 

Those darker materials could be everything from materials left behind by the evaporation of salty brines or that are rich in sulfur dioxide, according to NASA. The craters bulls-eye may contain material from the impacting body as well.

On Europa, the dearth of craters points to an active surface that could be anywhere from 10 million to 100 million years old. Fellow Jovian moon Callisto, by contrast, has a heavily cratered surface that could be old as 4 billion years.

The smoothness of Europas surface would mean the moon is constantly geologically speaking, at least re-paving itself.

That could indicate the ocean thought to lie below the ice could come into relatively frequent contact with the Europan surface, allowing for the exchange of nutrients and energy, and buoying the prospect that the moon may harbor extraterrestrial life.

NASA hopes to launch the Europa Orbiter in 2006 at the earliest on a mission to measure the thickness of Europas ice and to determine whether it indeed caps a global liquid ocean. A later mission would land on the moon for further science work.

Meanwhile, NASAs Galileo will remain in orbit around Jupiter until 2002 or later, when NASA plans to send it on a suicide plunge into the planets atmosphere. The $1.4 billion spacecraft reached Jupiter in 1995.