Space

July 31, 2013

NASA’s Cassini spacecraft reveals forces controlling Saturn moon jets

The intensity of jets of water ice and organic particles that shoot out from Saturn’s moon Enceladus depends on the moon’s proximity to the ringed planet, according to data obtained by NASA’s Cassini spacecraft.

The finding adds to evidence that a liquid water reservoir or ocean lurks under the icy surface of the moon. This is the first clear observation the bright plume emanating from Enceladus’ south pole varies predictably. The findings are detailed in a scientific paper in this week’s edition of Nature.

“The jets of Enceladus apparently work like adjustable garden hose nozzles,” said Matt Hedman, the paper’s lead author and a Cassini team scientist based at Cornell University in Ithaca, N.Y. “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.”

Cassini, which has been orbiting Saturn since 2004, discovered the jets that form the plume in 2005. The water ice and organic particles spray out from several narrow fissures nicknamed “tiger stripes.”

“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.”

For years scientists hypothesized the intensity of the jets likely varied over time, but no one had been able to show they changed in a recognizable pattern. Hedman and colleagues were able to see the changes by examining infrared data of the plume as a whole, obtained by Cassini’s visual and infrared mapping spectrometer, and looking at data gathered over a long period of time.

The VIMS instrument, which analyzed a wide range of data including the hydrocarbon composition of the surface of another Saturnian moon, Titan, and the seismological signs of Saturn’s vibrations in its rings, collected more than 200 images of the Enceladus plume from 2005 to 2012.

These data show the plume was dimmest when the moon was at the closest point in its orbit to Saturn. The plume gradually brightened until Enceladus was at the most distant point, where it was three to four times brighter than the dimmest detection. This is comparable to moving from a dim hallway into a brightly lit office.

Adding the brightness data to previous models of how Saturn squeezes Enceladus, the scientists deduced the stronger gravitational squeeze near the planet reduces the opening of the tiger stripes and the amount of material spraying out. They think the relaxing of Saturn’s gravity farther away from planet allows the tiger stripes to be more open and for the spray to escape in larger quantities..

“Cassini’s time at Saturn has shown us how active and kaleidoscopic this planet, its rings and its moons are,” said Linda Spilker, Cassini project scientist at JPL. “We’ve come a long way from the placid-looking Saturn that Galileo first spied through his telescope. We hope to learn more about the forces at work here as a microcosm for how our solar system formed.”

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. JPL manages the mission for NASA’s Science Mission Directorate in Washington. The VIMS team is based at the University of Arizona in Tucson.

 




All of this week's top headlines to your email every Friday.


 
 

 

President proclaims Memorial Day as ‘Day of Prayer’

President Barack Obama May 22 saluted the service and sacrifices of America’s military members–past and present–and proclaimed Memorial Day, May 25, 2015, “as a day of prayer for permanent peace, and I designate the hour beginning in each locality at 11 a.m. of that day as a time during which people may unite in prayer....
 
 

Air Force leaders’ Memorial Day message

Secretary of the Air Force Deborah Lee James and Air Force Chief of Staff Gen. Mark A. Welsh III send the following Memorial Day message to the Airmen of the Air Force and their families: To the Airmen of the United States Air Force and their Families: On Memorial Day, Americans pause in solemn remembrance...
 
 

Headlines May 22, 2015

News: Second Marine killed in Hawaii Osprey crash identified - Marine Corps officials have identified the second Marine to die as a result of the May 17 MV-22B Osprey crash as Lance Cpl. Matthew J. Determan of Maricopa, Ariz.   Business: Israel defense exports plunge to seven-year low - Israeli defense sales last year plunged to their...
 

 

News Briefs May 22, 2015

Ukrainian officer hit with third charge in Russia A third charge has been filed against a Ukrainian military officer who has been behind bars in Moscow for nearly a year over the deaths of two Russian journalists in Ukraine. Nadezhda Savchenko, who worked as a spotter for Ukrainian troops fighting separatist rebels in eastern Ukraine,...
 
 
Army photograph by C. Todd Lopez

Smart-mortar will help Soldiers more effectively hit targets

Army photograph by C. Todd Lopez Nick Baldwin and Evan Young, researchers with the Armament Research Development and Engineering Center at Picatinny Arsenal, Pennsylvania, discuss the 120mm Guided Enhanced Fragmentation Mortar ...
 
 

Air Force assigns new chief scientist

The Air Force announced the service’s new chief scientist to serve as a science and technology adviser to the secretary of the Air Force and the chief of staff of the Air Force, May 21. Dr. Greg Zacharias will be the 35th chief scientist and is ready to “dive in” to his new role. “I...
 




0 Comments


Be the first to comment!


Leave a Reply

Your email address will not be published. Required fields are marked *

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <strike> <strong>