Senin, 21 November 2011

New Hope for Life on Europa

 Evidence from a Nasa space probe suggests that Europa, the frosty moon of Jupiter, hides great lakes of liquid water just beneath its outer shell of ice. This gives new hope that the satellite's deep ocean of water could harbour life.
The information comes from the unmanned Galileo spacecraft, which arrived at Jupiter and its moons in 1995. It was the first spacecraft to investigate the Jovian system, revealed fresh information about the gas giant's atmosphere and sent back mountains of data to analyse.

It also returned evidence that one moon -- Europa -- hides an enormous ocean of liquid water, deep beneath the ice. It potentially contains more water than all of the Earth's oceans combined, but lying tens of miles beneath a shell of impenetrable ice made it seem unlikely to harbor life.
But fresh data reveals that there is a dramatic exchange between Europa's icy shell and the ocean beneath, and evidence for giant lakes just beneath the moon's surface. This would allow nutrients to easily travel between the surface and the ocean beneath, giving new hope that life could flourish in Europa's seas.
The data comes from Galileo images of an example of something that astrogeologists refer to as chaos terrain -- two roughly circular, bumpy features on Europa's surface. From looking at similar processes on Earth in ice shelves and under glaciers overlaying volcanoes, we can speculate about the geological process on Europa.

It suggests that the warmer water in the ocean beneath has welled up, which causes the surface ice to melt. This forms fractured cracks and jagged mounds of ice, and leaves behind massive lakes of water.
"The data opens up some compelling possibilities," said Mary Voytek, director of Nasa's Astrobiology Program at agency headquarters in Washington. "However, scientists worldwide will want to take a close look at this analysis and review the data before we can fully appreciate the implications of these results."

Europa is on the drawing board for another investigatory mission in the next decade. Nasa plans to launch the $4.7 billion Jupiter Europa Orbiter in 2020, with the intention of reaching the Jovian system in 2025. The probe would use an ice-penetrating radar to see exactly what lies beneath the moon's frigid shell.

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