27 February 2007

Time ripe to search for life on Europa

Cosmos Online
Life on Jupiter's moon Europa is just as feasible as life on Mars and worthy of NASA's attention, scientists have argued.
Time ripe to search for life on Europa

Europa, Jupiter's third largest moon, is as likely to harbour life as Mars, and should be given equal attention, scientists say. Credit: NASA

SYDNEY: Life on Jupiter’s moon Europa is just as feasible as life on Mars and worthy of NASA’s attention, scientists have argued.

“Because of the well-supported presence of water ice on Europa and the probability that there are briny oceans, Europa has to be a major target for the search for life in the Solar System,” said palaeobiologist Jere Lipps of the University of California, Berkeley. “Many of us are proposing that there is habitat there where we can expect to find evidence of life.”

Lipps and three colleagues took up the issue at the annual meeting of the American Association for the Advancement of Science in San Francisco last week. The group, organised by Lipps, are lobbying for equal attention to a place they feel is just as likely to harbour life as Mars.

Europa, the third largest of Jupiter’s moons, is thought to have a 20-kilometre thick ocean covered by a layer of ice. Lipps noted that while radiation at the surface of the moon could be intense enough to kill any Earth-like life, it would not penetrate more than a metre or two.

He explained that cracks, tubes, caves or overhangs in the surface might harbour life and proposed 25 habitats worthy of exploration. “Any exploration of the moon should examine these sites in detail,” he said.

Lipps argues that environments hospitable to life, the energy required for life and all the chemicals needed to support life, including oxygen, have been present on the moon for a long time – probably at least 60 million years, judging from crater counts on the moon’s surface.

Scientists suspect that liquid water close to freezing point (0°) is able to exist on Europa because of heat generated by tidal friction between the moon and its immense neighbour, the planet Jupiter.

“In Antarctica, every phylum of algae, protozoan, bacteria and animal lives in the ice, many of them in brine channels that don’t freeze,” said Lipps. “Life thrives in ice, it doesn’t mind at all.

“We’d like a mission to Europa and we’ve pointed out the likely places for life. It’s now up to the engineers, and to [U.S. space agency] NASA decision-makers and funders, to determine how to get there.”

Malcolm Walter, an astrobiologist at Macquarie University in Sydney, Australia, thinks that “Lipps has a very reasonable set of ideas. This idea isn’t new – it’s been around for about 20 years, but he has presented a clear set of figures and targets, providing a case for a very good search.”

But, he adds, “Mars has the edge for exploration. It has a wide range of environments, ancient oceans, volcanoes, rivers and the like, whereas Europa has an ocean and then a rocky centre. There’s more opportunity to find life on Mars.”

Despite this, Walter thinks that NASA will probably follow up on the proposal. But he described Lipp’s projections for having a spacecraft on Europa in 15 years as “very optimistic”.

“Europa does present the possibility of finding samples of life [which are] independent of the earth,” said Walter. “Like any similar discovery [this] would have a profound effect on our understanding of biology.”

More information:

Europa, NASA

Europa, Wikipedia

Jere Lipps, University of California


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