Cassini Spacecraft Glides Over Saturn Moon in Search for Life

6a00d8341bf7f753ef0133ec883e1f970b-320wi The Cassini spacecraft exploring Saturn got a new taste of the ringed planet’s moon Enceladus late Tuesday when it flew over the icy satellite in a gravity experiment. NASA’s Cassini probe glided low over Enceladus to perform an experiment designed to probe the moon’s interior composition. At closest approach, Cassini flew just 60 miles (100 km) above the surface of Enceladus at a speed of 15,000 mph relative to the moon.

The flyby, which took Cassini through the water-rich plume flaring out from Enceladus’ south polar region, occured  on April 27 at 8:10:17 p.m. EDT (0010:17 GMT on April 28).

Scientists plan to use Cassini’s radio science instrument to measure the gravitational pull of Enceladus against the steady radio link to NASA’s Deep Space Network here on Earth. Detecting any changes will help scientists understand what lies beneath Enceladus’ famous “tiger stripe” fractures, which spew water vapor and organic particles from the moon’s south polar region.

The experiment is also expected to help scientists learn if the south polar region’s sub-surface resembles a lava lamp. Scientists have hypothesized that a bubble of warmer ice periodically travels up to the crust and repaves it, explaining the quirky heat behavior and intriguing surface features of this region.


On the small, icy moon Enceladus, “the mother lode of all discoveries was discovered at the South Pole,” said Carolyn Porco in a talk at Harvard University. Porco is director of flight operations and imaging team leader for the Cassini spacecraft in orbit around Saturn. Her work involves taking detailed pictures in space, shots that offer insights into the nature of the universe, and signs of life elsewhere in the solar system.. She described Cassini’s findings of elevated temperatures in the moon’s polar region, as well as an enormous plume of icy particles shooting tens of thousands of kilometers into space.

Analysis of the icy trail, which includes water vapor and trace amounts of organic materials such as methane, carbon dioxide, and propane, suggests it is fueled by geysers erupting from a pocket of salt water within the moon.

The findings, noted Porco, point to the possibility of “an environment where life itself might be stirring.”

“Should we ever discover that a second genesis had occurred in our solar system, independently outside the Earth,” she added, “then I think at that point the spell is broken. The existence theorem has been proven, and we could safely infer from it that life was not a bug but a feature of the universe in which we live, that it’s commonplace and has occurred a staggering number of times.”

The Cassini probe launched in 1997 and arrived at Saturn in 2004, where it dropped the European Huygens probe on the cloudy surface of the planet’s largest moon Titan. Cassini was slated to be decommissioned in September of this year, but has received an extended mission that now runs through 2017.

The Cassini-Huygens mission is a joint project of NASA, the European Space Agency and the Italian Space Agency. It is managed by NASA’s Jet Propulsion Laboratory in Pasadena, Calif.

Casey Kazan via Harvard University


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