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Cassini Pinpoints Hot Sources Of Jets On Enceladus

Enceladus plume originate from the hot spots on the moon's "tiger stripe" fractures.
by Staff Writers
Boulder CO (SPX) Oct 19, 2007
A recent analysis of images from NASA's Cassini spacecraft provides conclusive evidence that the jets of fine, icy particles spraying from Saturn's moon Enceladus originate from the hottest spots on the moon's "tiger stripe" fractures that straddle the moon's south polar region. Members of Cassini's imaging team used two years' worth of pictures of the geologically active moon to locate the sources of the most prominent jets spouting from the moon's surface.

They then compared these surface source locations to hot spots detected by Cassini on Enceladus in 2005. The new results are published in the Oct. 11, 2007, issue of the journal Nature.

The researchers found that all of the jets appear to come from the four prominent tiger stripe fractures in the moon's active south polar region and, in almost every case, in the hottest areas detected by Cassini's composite and infrared spectrometer.

"This is the first time the visible jets have been tied directly to the tiger stripes," said Joseph Spitale, an imaging team associate and lead author of the Nature paper. Spitale works with Cassini imaging team leader and co-author Carolyn Porco, at the Space Science Institute in Boulder, Colo.

Imaging scientists suspected the individual jets, which collectively feed a plume that towers thousands of kilometers, or miles, above the moon, had been coming from the tiger stripes since the first images of the jets were taken in 2005. But this work provides the first conclusive proof of that hypothesis and provides the first direct evidence of a causal connection between the jets and the unusual heat radiating from the fractures.

To identify the jets' surface locations with certainty, the researchers carefully measured the apparent position and orientation of each jet as observed along the moon's edge by the spacecraft. By making measurements taken from a variety of viewing directions, they were able to pinpoint the jets' sources.

What Spitale and Porco found was intriguing: all measured jets fell on a fracture, but not all jets fell on a previously discovered hot spot. They conclude there are other hot spots to be found. "Some of our sources occur in regions not yet observed by Cassini's composite infrared spectrometer," said Spitale. "So we are predicting that future Cassini observations of those locations will find elevated temperatures."

The scientists also report the suggestion that the characteristics of the jets may depend on tidal frictional heating within the fractures and its variation over a full Enceladus orbit around Saturn. However, more work remains in investigating this issue.

The possibility, first suggested by the imaging team, that the jets may erupt from pockets of liquid water, together with the unusually warm temperatures and the organic material detected by Cassini in the vapor accompanying the icy particles, immediately shoved this small Saturnian moon into the spotlight as a potential solar system habitable zone.

But what actually lies beneath the surface to power the jets remains a mystery.

"These are findings with tremendously exciting implications and to say that I am eager to get to the bottom of it would be a cosmic understatement," said Porco. "Do the jets derive from near-surface liquid water or not? And if not, then how far down is the liquid water that we all suspect resides within this moon? Personally, I'd like to know the answer yesterday!"

The next opportunity for answering these questions will be when Cassini dips low over Enceladus and flies through the plume in March 2008, obtaining additional data about its chemical composition and the nature of its jets.

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Inspiring Views Celebrate Cassini's Diamond Anniversary
Boulder CO (SPX) Oct 16, 2007
Ten years ago today, NASA's Cassini spacecraft departed planet Earth from Cape Canaveral, Florida, and embarked on a seven-year long, circuitous journey of several billion miles across the solar system to the planet Saturn. To celebrate this special occasion, the mission's imaging team is releasing today a spate of captivating new images and movies of the ringed planet and some of its most photogenic companions.







  • Checking Out New Horizons
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  • Maneuver Puts New Horizons On A Straight Path To Pluto
  • Outbound To The Outerplanets At 7 AU

  • Hawaii Reveals Steamy Martian Underground
  • Hummocky And Shallow Maunder Crater
  • NASA extends Mars probes' mission for 5th time
  • Opportunity Begins Sustained Exploration Inside Crater

  • New Isotope Molecule May Add To Venus' Greenhouse Effect
  • 500 Days At Venus, And The Surprises Keep Coming
  • Up Up And Away To Venus
  • Spacecraft Tandem Provides New Views Of Venus

  • Critical Deep-Space Maneuver Targets MESSENGER For Its First Mercury Encounter
  • MESSENGER Team Wraps Up Radio Science Test
  • NASA Spacecraft Ready For Science-Rich Encounter With Venus
  • Venus Flyby Helps Drive The Message Home

  • New Horizons' SWAP instrument Reveals Complex Structure, Diverse Plasma Populations In Jupiter's Magnetotail
  • Polar lightning - not just an earthly phenomenon: study
  • Jupiter: Friend Or Foe
  • Researchers Produce Images Of Gases Escaping From Io

  • Predicting Planets
  • Star System Just Right For Building An Earth
  • Colors Of Alien Plants
  • All Planets Possible

  • Our First Lunar Program: What Did We Get From Apollo
  • USC Concept Synthesis Studio Colonizes The Moon With Bugs
  • Japanese lunar probe finishes critical phase
  • China moon probe to launch this month

  • ITT Sensors Aboard DigitalGlobe's WorldView-1 Satellite Capture First High-Res Images
  • Successful Image Taking By The High Definition Television
  • Boeing Launches WorldView-1 Earth-Imaging Satellite
  • New Faraway Sensors Warn Of Emerging Hurricane's Strength

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