Enceladus, which is planet Saturn’s sixth-largest moon, is particularly famous for its South Pole monster plume that continuously jets water vapor thousands of miles up into space.
The icy geyser emerges from the cracks on the moon’s surface and carries particles from the mysterious global ocean hidden underneath its icy crust. This is the second time Cassini performs a flyby of the remote moon this year, and the closest to date. By the end of the year, NASA plans to make one last flyby.
On Wednesday, Cassini swooped down at a speed of 19,000 miles per hour and reached a 30 mile altitude off Enceladus’ surface. The probe was able to collect close to 10,000 particles per second in the dive. The samples were later studied with help from the craft’s dust analyzer. But the data won’t be available to the public in the coming weeks since samples need to be further studied by scientists on Earth.
Earl Maize of the Cassini mission at NASA’ JPL said that the craft’s tools can detect complex organic molecules, but the instruments are not able to tell whether those molecules have a geological or biological origin.
Last month, NASA reported that Enceladus hosts a gigantic hidden ocean that is trapped between its rocky core and rugged crust. Scientists suspected that there might be a large body of water on the moon’s surface when they noticed a strange wobble in the moon’s orbit around Saturn.
But scientists weren’t able to explain what forces keep the water liquid and what pushes up those icy plumes at the south pole. This week’s flyby is designed to unveil these mysteries.
Curt Niebur, another Cassini mission member, thinks that there is a hidden heat source underneath the space body’s crust. The source may be responsible to the melt water and may have kept the ocean liquid. NASA scientists speculate that the source may be caused by a phenomenon called tidal heating. And, tidal heating on Enceladus may be triggered by the moon’s interaction with other moons’ and Saturn’s gravitational fields, scientists suggest.
Yet, critics of the theory said that their calculations showed that tidal heating couldn’t generate enough energy to keep an entire ocean warm. And the cause of the icy plumes at the moon’s south pole is also a topic of hot debates within scientific community worldwide.
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