BBC News Online: Sci/Tech

Galileo sends new Jupiter moon views

Callisto's surface is heavily cratered
Image: Nasa/JPL/DLR(German Aerospace Centre)

The pictures were taken by the Galileo probe in May and are the highest resolution view yet seen of any of Jupiter's moons.

They show a spiky landscape of bright ice and dark dust with signs of slow but active surface erosion.

Callisto is about the same size as the planet Mercury and its surface is the most heavily cratered of any moon in the Solar System, signifying that it is geologically "dead".

There is no clear evidence that Callisto has experienced the volcanic activity or tectonic shifting that have erased some or all of the impact craters on Jupiter's other three large moons, Nasa says.

The close-up images show craters as small as about three meters (10 feet) across.

Image analysts are counting the craters as a means to estimate Callisto's age and compare their calculations with those for other moons of Jupiter.