Enceladus’s Ice Jets Are Controlled by Saturn's Gravitational Pull

Saturn's geyser moon Enceladus is one of the most geologically active worlds in our solar system. NASA's Cassini probe that is orbiting the Saturn system since 2004 had earlier discovered jets of giant bright plumes of water ice and organic particles from the moon's South Polar Region.

The scientists wondered why Enceladus became so active despite being the farthest from its ringed parent planet while Dione just sputtered along. 

With the help of the images provided by Cassini-Huygens spacecraft, a team of researchers from Cornell University have been able to explain this activity. According to the researchers, the intensity of the jets of water ice and organic particles that spew from the moon Enceladus depends on the moon's proximity to the ringed planet,

It is Saturn's gravitational pull that is responsible for the mysterious hot geysers on Saturn's moon Enceladus that spray water ice and organic particles into the space.

It was in 2005 that Cassini discovered jets from the plume. The water ice and organic particles are sprayed into the space from many narrow fissures dubbed 'tiger stripes'. This latest finding adds to the previous evidence about the presence of liquid water reservoir or ocean below the icy surface of the moon.

"The jets of Enceladus apparently work like adjustable garden hose nozzles," Matt Hedman, the paper's lead author and a Cassini team scientist based at Cornell University in Ithaca, N.Y., said in a press statement. "The nozzles are almost closed when Enceladus is closer to Saturn and are most open when the moon is farthest away. We think this has to do with how Saturn squeezes and releases the moon with its gravity."

Scientists had earlier assumed that the intensity of the jets changed over time but it was never known that vary in a recognizable pattern. It was the team from Cornell University that noticed the changes by examining the infrared data of the plume as a whole that was provided by Cassini's visual and infrared mapping spectrometer (VIMS). They also worked on the data provided by Cassini till date. The VIMS instrument provided more than 200 images of the Enceladus plume that was captured from 2005 to 2012.

"The way the jets react so responsively to changing stresses on Enceladus suggests they have their origins in a large body of liquid water," said Christophe Sotin, a co-author and Cassini team member at NASA's Jet Propulsion Laboratory in Pasadena, Calif. "Liquid water was key to the development of life on Earth, so these discoveries whet the appetite to know whether life exists everywhere water is present."

The data revealed that when the moon is at the closest point in its orbit to Saturn, the plume is dimmest. The plume gradually brightens as Enceladus moves to a distant point and shines three to four times brighter than the dimmest point.

The researchers also discovered that stronger the gravitational pull near the planet, lesser the tiger stripes open and less material is sprayed out. And when it is farthest from the Saturn's gravity, the tiger stripes open more and larger quantities of spray escape.