US astronomers looking for life in the solar system believe that Europa, one of the moons of Jupiter, which has an ocean, is much more promising than desert-covered Mars, which is currently the focus of the US government's attention.

"Europa is the most likely place in our solar system beyond Earth to possess .... life," said Robert Pappalardo, a planetary scientist at NASA's Jet Propulsion Laboratory (JPL) in Pasadena, California.

Complex and beautiful patterns adorn the icy surface of Jupiter's moon Europa.

"And it is the place we should be exploring now that we have a concept mission we think is the right one to get there for an affordable cost," he continued.

"Europa is the most promising in terms of habitability because of its relatively thin ice shelf and an ocean ... And we know there are oxidants on the surface of Europa."