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Cassini tastes icy material from Saturn moon geyser

Posted: November 4, 2009

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The Cassini spacecraft touring Saturn is beaming back data and stunning imagery from Monday's flyby of Enceladus, an enigmatic ice-covered moon with geysers of material spewing from fissures on the surface.

Cassini's camera took this raw picture of Enceladus from a distance of 117,000 miles, showing plumes of material at the top of the image. Credit: NASA/JPL/Space Science Institute
The focus of Monday's encounter was to measure the make-up of the plums and observe ice fissures called tiger stripes at the moon's south pole. Scientists believe the tiger stripes are the origin of the jets.

Cassini, in its sixth year at Saturn, flew 64 miles above the surface of Enceladus at about 0740 GMT (2:40 a.m. EST) Monday. It was the seventh time the probe has approached Enceladus, but Monday's flyby was targeted to sail through the heart of the moon's south pole plume.

The encounter was designed to spend about one minute inside the icy cloud.

Earlier flybys detected water vapor, sodium and organic molecules in the plume, but scientists hope Monday's visit will fill in the blanks and provide the best data on its composition.

Officials conducted studies to ensure Cassini could safely fly through the plume while conserving precious maneuvering propellant. During the flyby, Cassini was traveling at a speedy clip of five miles per second, so engineers wanted to make sure particles in the plume would not damage the spacecraft.

This raw picture of the surface of Enceladus was taken at a distance of about 8,500 miles. Credit: NASA/JPL/Space Science Institute
Cassini discovered the jets in 2005, and scientists think the plume could be indicative of a liquid ocean harbored underneath the icy surface of Enceladus.

Enceladus is about 500 kilometers, or 310 miles, in diameter, about the size of Arizona. Enceladus is the smallest object in the solar system known to have such an active surface geology.

Immense heat inside Enceladus could be driving the geysers, and researchers are curious to learn more about the extent of organic molecules on the moon to see if it has the conditions necessary for life.

Enceladus reflects nearly all of the sunlight reaching the surface, plunging temperatures to frigid levels approaching -330 degrees F.

Cassini previously flew a scant 14 miles above the surface of Enceladus in March 2008. A flyby about 1,000 miles from Enceladus is planned for Nov. 20, followed by another 60-mile approach next April.