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: SpaceX ship leaves ISS for Earth loaded with lab results

add to favorites email to friend print save as pdf

Related Stories

Ten years of Cassini

Sep 09, 2014

Ten years ago, the Cassini-Huygens mission entered the Saturnian System and in January 2005, the Huygens probe landed softly on the surface of Saturn's largest moon, Titan. These historic events, which revolutionized ...

How Titan's haze help us understand life's origins

Aug 25, 2014

Where did life on Earth come from? There are several theories as to what might have happened. Maybe comets came bearing organic material, or life was transported from another planet such as Mars, or something ...

Voyager map details Neptune's strange moon Triton

Aug 22, 2014

(Phys.org) —NASA's Voyager 2 spacecraft gave humanity its first close-up look at Neptune and its moon Triton in the summer of 1989. Like an old film, Voyager's historic footage of Triton has been "restored" ...

Follow the radio waves to exomoons, astrophysicists say

Aug 11, 2014

Scientists hunting for life beyond Earth have discovered more than 1,800 planets outside our solar system, or exoplanets, in recent years, but so far, no one has been able to confirm an exomoon. Now, physicists ...

Recommended for you

Hinode satellite captures X-ray footage of solar eclipse

Oct 24, 2014

The moon passed between the Earth and the sun on Thursday, Oct. 23. While avid stargazers in North America looked up to watch the spectacle, the best vantage point was several hundred miles above the North ...

User comments : 0