NASA spacecraft makes deepest dive yet into Saturn moon's jets to find life

London, November 3 : NASA's Cassini spacecraft has made its deepest plunge yet into the plumes of Saturn's moon Enceladus, which might reveal complex organic molecules that could hint at life.

Researchers have been fascinated with Enceladus since July 2005, when Cassini revealed plumes of ice particles and water vapor shooting out from the moon’s south pole.

The origin of the plumes is still being debated. But, evidence is mounting that the moon may have liquid water beneath its surface, a potential habitat for life.

Until now, Cassini has maintained a cautious distance from the densest part of the plumes, flying at distances of 260 kilometres or more from the surface.

But, according to a report by New Scientist, mission members changed that policy after they determined that ice grains would not pose a threat to the spacecraft if it made a slow, close approach of the plume’s central regions.

They used the tug of Saturn’s biggest moon, Titan, to steer Cassini onto a path that on November 2 took it into the plumes just 100 km above Enceladus’s south pole.

There, the plumes emanate from long fissures called tiger stripes.

“We won’t know until we’ve got the data,” said planetary scientist John Spencer of the Southwest Research Institute in Boulder, Colorado. “We may find something completely unexpected. We’re going somewhere we have never been before,” he added.

Because the plume is denser closer to the moon’s surface, the dive could reveal molecules that have so far evaded detection because they are fairly rare.

These could include complex organic molecules that might hint at life.

Researchers also hope to catch evidence of krypton and other noble gases, unreactive atoms that will have remained stable over the course of Enceladus’s lifetime.

The abundance of these elements changes depending on how they are trapped; so this measurement could shed more light on how and where in the solar system Enceladus formed.

Cassini is slated to make another deep plunge into the plumes in April 2010.

But unlike the current fly-through, at that time it will not use its thrusters. This will enable precise measurements of the moon’s gravitational tug, which could help reveal whether Enceladus harbours a large internal ocean.