Subscribe free to our newsletters via your
  Saturn News  

Subscribe free to our newsletters via your

Cassini Captures Best View Yet Of Saturn's Ring Currents

This is a false color map of the intensity of the energetic neutral atoms emitted from the ring current through a processed called charge exchange. In this process a trapped energetic ion steals an electron from cold gas atoms and becomes neutral and escapes the magnetic field.
by Staff Writers
Baltimore MD (SPX) Dec 14, 2007
Scientists have gotten their best "look" ever at the invisible ring of energetic ions trapped in Saturn's giant magnetic field, finding that it is asymmetric and dynamic, unlike similar rings that appear around Earth.

Using the Magnetospheric Imaging Instrument on NASA's Cassini spacecraft, a team led by Dr. S. Krimigis of the Johns Hopkins University Applied Physics Laboratory (APL) discovered that Saturn's ring of energetic ions - called a "ring current" - is a warped disc that is deflected by the solar wind out of the equatorial plane on the planet's night side and thickens dramatically on the day side. The images were obtained by a unique camera that Krimigis says "visualizes the invisible" and show the plasma and radiation belts in Saturn's environment.

In the Dec. 13 issue of the journal Nature, Krimigis' team describes how Saturn's ring current changes over time; it's a dynamic system, doughnut shaped but sometimes appearing like someone took a bite out of it. They also found that Saturn's ring current is persistently asymmetric - unlike Earth's - and it rotates closely in-step with Saturn itself. Ring currents form when hot ionized gas (known as plasma) becomes trapped on a planet's magnetic field lines. The main source of the plasma that forms Saturn's ring current is material from the gas vented by geysers on the moon Enceladus.

At Earth, ring currents form during large solar wind-driven magnetic storms, although they fade quickly as the driving solar wind disturbance recedes into deep space. At Saturn, the Magnetospheric Imaging Instrument (MIMI) observed that the ring current's intensity seemed only weakly related to solar activity.

"We might get a more intense reading when a solar wind pressure spike passes by," says Dr. D. Mitchell, a MIMI co-investigator from APL. "But the surprise is that Saturn's ring current didn't become symmetric or dissipate as it does at Earth. It stayed lumpy and rotated around the planet several times. We don't know exactly why that happens, but we have seen it exhibit this behavior repeatedly."

The presence of a ring current around Saturn was first suggested in the early 1980s from magnetic anomalies observed by NASA's Pioneer 11 and Voyager 1 and 2 spacecraft. But Saturn's ring current had never been mapped on a global scale; only small areas were mapped previously, and not in this detail. MIMI was designed for just this purpose; developed by an APL-led international team, MIMI has three distinct sensors, one of which contributed the images for this work.

False-color images accompanying the Nature article were taken by MIMI's ion and neutral camera and show the intensity of the energetic neutral atoms emitted from the ring current through a process called charge exchange. This happens when a trapped energetic ion steals an electron from a cold gas atom, becomes neutral and escapes the magnetic field. Scientists are using these images to create a map of the invisible ring current, which is roughly five times farther from Saturn than its famous icy rings.

MIMI gathered the images for the Nature paper in March 2007 as Cassini looped nearly 1.5 million kilometers (920,000 miles) over Saturn's poles, giving the instrument a bird's eye view of the magnetic activity swirling around the planet.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington, D.C. APL's Krimigis is the principal investigator for MIMI, which was designed and built and is operated by an Applied Physics Laboratory-led team.

The University of Maryland and the Max Planck Institute for Solar Physics in Germany contributed two of the three sensors. Part of the analyses for this work was performed as a collaborative effort with the Academy of Athens in Greece.

Related Links
Cassini-Huygens mission
Explore The Ring World of Saturn and her moons
Jupiter and its Moons
The million outer planets of a star called Sol
News Flash at Mercury

Memory Foam Mattress Review
Newsletters :: SpaceDaily :: SpaceWar :: TerraDaily :: Energy Daily
XML Feeds :: Space News :: Earth News :: War News :: Solar Energy News

Planetary Scientists Close In On Saturn' Elusive Rotation
Paris, France (ESA) Dec 14, 2007
Somewhere deep below Saturn's cloud tops, the planet rotates at a constant speed. Determining this interior period of rotation has proven extremely complicated. Now, with new Cassini results, a team of European scientists have taken an important step forward.

  • The PI's Perspective: Autumn 2007: Onward to the Kuiper Belt
  • Data For The Next Generations
  • Goddard Instrument Makes Cover Of Science
  • Checking Out New Horizons

  • Mars Orbiter Examines Lace And Lizard Skin Terrain
  • Building Blocks Of Life Formed On Mars
  • Software Helps Mars Rovers Find Winter Havens
  • Mars Express Watches A Dust Storm Engulf Mars

  • The Restless Atmosphere Of Venus
  • The Unexpected Temperature Profile Of Venus's Atmosphere
  • The Venusian Climate And Its Evolution
  • Earth-like Venus

  • Messenger Exits Longest Solar Conjunction Period of Mission
  • MESSENGER Completes Fifty Percent Of Cruise Phase
  • Critical Deep-Space Maneuver Targets MESSENGER For Its First Mercury Encounter
  • MESSENGER Team Wraps Up Radio Science Test

  • Return To Europa: A Closer Look Is Possible
  • Rethinking Jupiter
  • Jovian Magnetosphere Circulates Magnetic Field Very Differently From Earth
  • New Horizons' SWAP instrument Reveals Complex Structure, Diverse Plasma Populations In Jupiter's Magnetotail

  • Gliese 581: One Planet Might Indeed Be Habitable
  • Hazy Red Sunset On Extrasolar Planet
  • First Ground-Based Detection Of Extra-Solar Planet Atmsosphere Using Hobby-Eberly Telescope
  • When Do Gas Giants Reach The Point Of No Return

  • China Foresees Arduous Future Tasks In Space Probe
  • Lighting Up The Lunar Night With Fuel Cells
  • New NASA Mission To Reveal Moon's Internal Structure And Evolution
  • Earth's Magnetic Field Could Help Protect Astronauts Working On The Moon

  • Outside View: Russia's new sats -- Part 2
  • Use Space Technology And IT For Rural Development
  • China, Brazil give Africa free satellite land images
  • Ministerial Summit On Global Earth Observation System Of Systems

  • The content herein, unless otherwise known to be public domain, are Copyright Space.TV Corporation. AFP and UPI Wire Stories are copyright Agence France-Presse and United Press International. ESA Portal Reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space.TV Corp on any Web page published or hosted by Space.TV Corp. Privacy Statement