Cassini confirms a dynamic atmosphere at Saturn’s moon Enceladus

July 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: Water, water, everywhere – where to drink in the solar system

Related Stories

Mystery of Saturn's 'F ring' cracked, says study

August 17, 2015

An enigmatic ring of icy particles circling Saturn, herded into a narrow ribbon by two tiny moons, was probably born of a cosmic collision, according to a study published Monday in Nature Geoscience.

The dwarf planet Ceres

August 12, 2015

The asteroid belt is a pretty interesting place. In addition to containing between 2.8 and 3.2 quintillion metric tons of matter, the region is also home to many minor planets. The largest of these, known as Ceres, is not ...

The moons of Saturn

August 7, 2015

Saturn is well known for being a gas giant, and for its impressive ring system. But it would it surprise you to know that this planet also has the second-most moons in the solar system, second only to Jupiter? Yes, Saturn ...

The Planet Saturn

August 3, 2015

The farthest planet from the Sun that be observed with the naked eye, the existence of Saturn has been known for thousands of years. And much like all celestial bodies that can be observed with the aid of instruments – ...

Recommended for you

Long-sought chiral anomaly detected in crystalline material

September 3, 2015

A study by Princeton researchers presents evidence for a long-sought phenomenon—first theorized in the 1960s and predicted to be found in crystals in 1983—called the "chiral anomaly" in a metallic compound of sodium and ...

Making nanowires from protein and DNA

September 3, 2015

The ability to custom design biological materials such as protein and DNA opens up technological possibilities that were unimaginable just a few decades ago. For example, synthetic structures made of DNA could one day be ...

0 comments

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.