Monday, 05 May, 2008 Science

Spacecraft Observes Powerful Electrical Storm on Saturn


The mission of Cassini spacecraft continues as it monitors the powerful electrical storm on Saturn, where the lightning is 10,000 times more powerful than the lightning on Earth.

The storm that generates the powerful lightning has been observed by the NASA scientists that work on Cassini-Huygens mission. It is worth mentioning that the observed lightning is the longest persistently observed electrical storm examined by the spacecraft. The electrical storms on Saturn look just like the ones observed on Earth. The only difference is their size. The diameters of the Saturn's electrical storms reach several thousands of kilometers. In addition the radio signals that the lightning generates are more powerful than the ones on Earth by thousands of times.

The storm on Saturn generates flashes of lighting that produce radio waves. These waves are called Saturn electrostatic discharges. For the first time these electrostatic discharges have been identified on November 27, 2007. A week later the imaging cameras of the spacecraft for the first time were able to identify both the position and appearance of the electrical storm.

"The electrostatic radio outbursts have waxed and waned in intensity for five months now. We saw similar storms in 2004 and 2006 that each lasted for nearly a month, but this storm is longer-lived by far. And it appeared after nearly two years during which we did not detect any electrical storm activity from Saturn," said Georg Fischer, who works as an associate with the radio and plasma wave science team at the University of Iowa, Iowa City.

The newly observed storm on Saturn is found in the southern hemisphere of the planet, which is a region dubbed by the mission scientists "Storm Alley." This is the place where the previous electrical discharges were spotted by Cassini.

"In order to see the storm, the imaging cameras have to be looking at the right place at the right time, and whenever our cameras see the storm, the radio outbursts are there," mentioned Ulyana Dyudina, who works as an associate of the Cassini imaging team at the California Institute of Technology in Pasadena, California.

The radio plasma wave tool, used by the spacecraft, identifies the storm each time it rotates into the view. Scientists found that this happens every 10 hours and 40 minutes, which is Saturn's approximate length of the day. It's interesting to note that the storm emits a radio pulse every few seconds. The radio pulse lasts for approximately tenth of a second. The Cassini spacecraft is able to identify these radio waves even when the Saturn's electrical storm is over the horizon.

Scientists hope that the storm on Saturn will give them information on the processes powering the planet's lightning activity. During the change of the seasons, scientists will continuously monitor the area of the Storm Alley.

It is worth mentioning that the Cassini-Huygens mission represents a team project of NASA, the European Space Agency and the Italian Space Agency. JPL (Jet Propulsion Laboratory), which is a division of Caltech, administers the Cassini mission for NASA's Science Mission Directorate, Washington, D.C. As center for robotic exploration of the solar system, JLC was the one to develop and assemble Cassini orbiter as well as the spacecraft's two onboard cameras.

The images of the storm can be viewed at: and and .

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