Data from a Nasa probe has revealed that enough heat from inside the Red Planet might be trapped at the poles to melt underground water ice.

Dr Krishnan Khurana, University of California, describes part of the findings

This could create lakes below the ice caps - and where there is water, there could be life.

The Global Surveyor probe has also detected what may be a clathrate - a layer of water surrounding carbon dioxide molecules under the surface.

This would help retain heat and nurture life.

Europa: Warm under icy exterior

New observations of Jupiter's moon Europa have also raised hopes of finding water, Nature magazine has reported.

When the Voyager spacecraft passed Jupiter in the 1970s they discovered that Europa - only slightly smaller than our own moon - was covered in a layer of ice.

But because Europa may have a warm interior it was suggested that between the ice crust and the warm rocks may be an ocean of warm water.

Since the Galileo spacecraft arrived at Jupiter in December 1995 it has taken many photographs of Europa and all of them have tantalised astronomers with the possibility of a sub-surface ocean.

Search for life

Despite lacking a magnetic field, Europa seems to disturb Jupiter's strong field, a fact that scientists say is best explained by water beneath its icy surface.

Many scientists now regard Europa - not Mars - as the most promising place to look for life off the Earth. There are plans to send a probe to orbit the moon.

The proposal is to land on its surface and use hot water to melt a way through the ice crust and emerge into the dark ocean below - to begin a search for life.