Scientists turn eyes toward Europa

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

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

"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 says.

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

At the request of NASA, a proposed mission to explore Europa was revised to significantly reduce the cost, the scientist told the media on Friday on the sidelines of an annual conference of the American Association for the Advancement of Science.

As a result of this review, the JPL and the Applied Physics Laboratory at Johns Hopkins University in Maryland developed a new exploration project named Clipper with a total coast of $US2 billion ($A1.95 billion) minus the launch.

Following the successful example of Cassini, a probe that explored Titan, a moon of Saturn, a spacecraft would orbit Jupiter and conduct numerous close flybys of Europa.

If the plan is approved, Clipper could be launched by 2021 and take three to six years to reach Europa. By comparison, it takes six months to reach Mars.

But NASA announced at the end of 2012 that there would be no funds for the Clipper mission, he said.

Noting that Mars consumed most attention, Pappalardo said the agency should not ignore planets that have a high scientific priority.

In his view, life could have existed on Mars several billion years ago, but Europa could have life today.

Europa was closely observed for the first time by the twin Voyager probes in 1979 and then, in more detail, by Galileo in the 1990s. Sky News