Cassini confirms a dynamic atmosphere at Saturn’s moon Enceladus

Jul 29, 2005
Enceladus

The latest close flyby of Saturn’s icy moon Enceladus by NASA’s Cassini spacecraft confirms that the moon has a significant, extended and dynamic atmosphere. The flyby, which took place on 14th July 2005, was Cassini’s lowest altitude flyby of any object to date, a mere 173 kilometres (108 miles) above the surface of Enceladus.

Image: This artist concept shows the detection of an dynamic atmosphere on Saturn's icy moon Enceladus. The Cassini magnetometer instrument is designed to measure the magnitude and direction of the magnetic fields of Saturn and its moons. During Cassini's three close flybys of Enceladus- Feb. 17, March 9 and July 14-the instrument detected a bending of the magnetic field around Enceladus due to electric currents generated by the interaction of atmospheric particles and the magnetosphere of Saturn.

The graphic shows the magnetic field observed by Cassini as well as the predicted neutral cloud being vented from the south pole. Cassini's magnetometer observed bending of the magnetic field consistent with its draping around a conducting object, which indicates that the Saturnian plasma is being diverted away from an extended atmosphere.
Credit: NASA/JPL


The 500 km diameter moon Enceladus is a very bright icy moon at a distance of 4 Saturn radii away from Saturn. It has long been associated with the formation of the E ring, Saturn’s outermost ring. The first two more distant flybys of Enceladus on February 17th at an altitude of 1,167 kilometres (725 miles), and on March 9th, 500 kilometres (310 miles) above Enceladus’ surface had shown draping or bending of the magnetic field around the moon, revealing that Enceladus was acting as a large obstacle to the flow of plasma and magnetic field from Saturn by its extended asymmetric atmosphere.

The recent close flyby confirms and extends the observations from the two more distant flybys which took place earlier this year. Although no other instruments on the Cassini spacecraft had detected evidence of this atmosphere on the first two flybys, on the basis of the magnetometer [MAG] instrument observations alone a decision was made to modify the spacecraft trajectory for the 14th July encounter to fly much closer to the surface of Enceladus.

Professor Michele Dougherty from Imperial College London, who is Principal Investigator on the Magnetometer instrument on Cassini, says “These latest observations are very exciting, they confirm the existence of an atmosphere which we predicted from the distant earlier flybys and they will also allow us to gain a much better understanding of the processes taking place which are producing this very exotic atmosphere.”

Observations from numerous instruments now confirm what MAG was able to see from a great distance. Not only is the magnetic field even more strongly bent around the atmospheric obstacle connected to the moon but the other instruments also detected the presence of the atmosphere. The magnetic data also suggests that the atmosphere is not symmetric and may be arising from a comet-like jet from the southern hemisphere. Also the spacecraft passed right through the electric current carrying region associated with the atmospheric interaction.

Explore further: SDO captures images of two mid-level flares

add to favorites email to friend print save as pdf

Related Stories

Why we need more than one mission to Mars

Dec 05, 2014

After a 24-hour delay due to bad weather, the first test launch of the Orion spacecraft by NASA is underway with the ultimate goal of putting human beings on Mars. ...

How can we search for life on icy moons such as Europa?

Nov 24, 2014

Our solar system is host to a wealth of icy worlds that may have water beneath the surface. The Cassini spacecraft recently uncovered evidence of a possible ocean under the surface of Saturn's moon, Mimas.

A close-up with a comet

Nov 11, 2014

Even as Tom Economou approached retirement age in 1994, he began planning an instrument for the European Space Agency's Rosetta mission to a comet. He still remembers the reaction of Riccardo Levi-Setti, ...

Preparing for alien life

Nov 10, 2014

At a recent event sponsored by NASA and the Library of Congress, a group of scientists and scholars explored how we might prepare for the inevitable discovery of life beyond Earth.

Life can survive on much less water than you might think

Nov 04, 2014

"Follow the water" has long been the mantra of our scientific search for alien life in the Solar System and beyond. We continue seeking conditions where water can remain liquid either on a world's surface ...

Recommended for you

SDO captures images of two mid-level flares

13 minutes ago

The sun emitted a mid-level flare on Dec. 18, 2014, at 4:58 p.m. EST. NASA's Solar Dynamics Observatory, which watches the sun constantly, captured an image of the event. Solar flares are powerful bursts ...

Why is Venus so horrible?

7 hours ago

Venus sucks. Seriously, it's the worst. The global temperature is as hot as an oven, the atmospheric pressure is 90 times Earth, and it rains sulfuric acid. Every part of the surface of Venus would kill you ...

Image: Christmas wrapping the Sentinel-3A antenna

9 hours ago

The moment a team of technicians, gowned like hospital surgeons, wraps the Sentinel-3A radar altimeter in multilayer insulation to protect it from the temperature extremes found in Earth orbit.

Video: Flying over Becquerel

9 hours ago

This latest release from the camera on ESA's Mars Express is a simulated flight over the Becquerel crater, showing large-scale deposits of sedimentary material.

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.