Cassini Images First Extraterrestrial Lightnings

The phenomenon was observed in Saturn's atmosphere

  This image from NASA's Cassini spacecraft -- the first of its kind -- shows lightning on Saturn's night side flashing in a cloud that is illuminated by light from Saturn's rings
The NASA Cassini spacecraft can add another world first to its already-impressive tally of accomplishment. Scientists at the Pasadena, California-based NASA Jet Propulsion Laboratory (JPL) announce that the orbiter is the first probe ever to image lightning strikes on another planet. The explorations robot has been orbiting the gas giant Saturn since July 1, 2004, and it has already sent back exquisite and outstanding images of the planet, its moons and its intricate ring system.

With the newly-received data, investigators at NASA were able to piece together the first short video clip of lightning discharges on another planet. In addition to the video components, the film is also completed by the crackle of radio waves, which Cassini's sensitive instruments detected when the electrical discharges took place.

“This is the first time we have the visible lightning flash together with the radio data. Now that the radio and visible light data line up, we know for sure we are seeing powerful lightning storms,” says Space Research Institute radio and plasma wave science team associate member, Georg Fischer. The facility is located in the city of Graz, Austria.

“What's interesting is that the storms are as powerful – or even more powerful – at Saturn as on Earth. But they occur much less frequently, with usually only one happening on the planet at any given time, though it can last for months,” adds Cassini imaging science subsystem team member Andrew Ingersoll. The expert is based at the California Institute of Technology (Caltech), which houses and manages the JPL.

“The visible-light images tell us a lot about the lightning. Now we can begin to measure how powerful these storms are, where they form in the cloud layer and how the optical intensity relates to the total energy of the thunderstorms,” concludes Caltech expert Ulyana Dyudina, who was the first person to see the lightnings on Saturn. He is also an associate of the Cassini imaging team. Details of the discovery have already been accepted for publication in an upcoming issue of the esteemed scientific journal Geophysical Research Letters.

The Cassini-Huygens mission was a cooperative project of NASA, the European Space Agency (ESA) and the Italian Space Agency (ASI). The JPL manages the Cassini-Huygens mission for NASA Science Mission Directorate, at the agency's Headquarters in Washington DC. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The Huygens mission landed successfully on Titan in January, 2005, and began relaying data from the surface. Though never designed to serve as a lander, the instrument continued to send signals for about 90 minutes after impact.


By    15 Apr 2010, 10:54 GMT