* Astronomy

Blobrana · L

RE: Enceladus

Blobrana · L

This map of the surface of Enceladus was generated from images taken by NASA's Cassini and Voyager spacecraft, and illustrates the imaging coverage planned for Cassini's very close flyby of the geologically active moon on March 12, 2008.
This flyby will be Cassini's closest approach to Enceladus so far, the fourth and final Enceladus flyby of the four-year prime mission, and the first of four close brushes with this moon that have been proposed for 2008. At closest approach, the spacecraft will be only about 50 kilometres above the surface of Enceladus, and will pass the moon at a speed of about 14 kilometres per second. Enceladus is 505 kilometres across.

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Credit NASA

During this flyby, as well as the flyby on Oct. 9, 2008, Cassini's in-situ instruments will make the most of the remarkably close encounters. The imaging cameras and the other optical remote sensing instruments will get a better look at the moon during the flybys that have been proposed for Aug. 11 and Oct. 31. Radar will acquire albedo measurements during the March and Oct. encounters.
Coloured lines on the map enclose regions that will be covered at different imaging scales as Cassini encounters Enceladus. The highest-resolution images, about 200 meters per pixel, will be obtained over the cratered terrains of the northern hemisphere, prior to closest approach. Cassini will also acquire images soon after closest approach. However, the moon will be in eclipse during this time--sitting within Saturn's shadow--and surface features will likely not be visible. Additional images at resolutions above 700 meters per pixel will be acquired following the eclipse period.

Blobrana · L

An enormous plume of dust and water spurts violently into space from the south pole of Enceladus, Saturn's sixth-largest moon. This raging eruption has intrigued scientists ever since the Cassini spacecraft provided dramatic images of the phenomenon.
Now, physicist Nikolai Brilliantov, at the University of Leicester, and colleagues in Germany, have revealed why the dust particles in the plume emerge more slowly than the water vapour escaping from the moon's icy crust.
Enceladus orbits in Saturn's outermost "E" ring. It is one of only three outer solar system bodies that produce active eruptions of dust and water vapour. Moreover, aside from the Earth, Mars, and Jupiter's moon Europa, it is one of the only places in the solar system for which astronomers have direct evidence of the presence of water.

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Blobrana · L

Scientists on Wednesday said they have an explanation how one of Saturn's moons can spew out a giant plume of water vapour, adding to evidence a source of life -- water -- lies beneath the moon's frozen surface.
Using a computer model, German researchers showed the temperature at the bottom of surface cracks on Enceladus has to be about 0 degrees Celsius, the so-called triple point of water where vapour, ice and liquid water all can coexist.

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Blobrana · L

One of Saturn's rings does housecleaning, soaking up material gushing from the fountains on Saturn's tiny ice moon Enceladus, according to new observations from the Cassini spacecraft.

"Saturn's A-ring and Enceladus are separated by 100,000 kilometres, yet theres a physical connection between the two. Prior to Cassini, it was believed that the two bodies were separate and distinct entities, but Cassinis unique observations indicate that Enceladus is actually delivering a portion of its mass directly to the outer edge of the A-ring" - Dr. William Farrell of NASA's Goddard Space Flight Centre in Greenbelt, Md.

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Blobrana · L

Plumes of steam on Saturn's moon Enceladus are not spurting from a liquid water ocean beneath the icy surface as previously thought, a controversial new study argues. If the conclusion is borne out by future observations, it would be bad news for scientists hoping to use the plumes to probe an environment that could host life.
Scientists were surprised when the Cassini spacecraft discovered plumes of water vapour coming from icy Enceladus in 2005. Some suggested that the plumes were squirting up from an ocean of liquid water beneath the surface of the 500-kilometre-wide moon, raising hopes that life could be present there.
But a new study led by Nick Schneider of the University of Colorado in Boulder, US, casts doubt on the idea that the plumes originate in an ocean of liquid water.

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Blobrana · L

An ocean is not the source of the jets emanating from Saturn's moon Enceladus, a new study concludes.
The research questions the moon's promise as a target in the search for life beyond Earth and has stirred controversy among scientists who dispute its conclusions.
A chemical analysis of Enceladus, led by University of Colorado planetary scientist Nick Schneider, failed to detect sodium, an element scientists say should be in a body of water that has had billions of years of contact with rock.

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Blobrana · L

The image of Enceladus was taken by the Cassini spaceprobe in visible light with the narrow-angle camera on Oct. 26, 2007. The view was obtained at a distance of approximately 1.6 million kilometres from Enceladus.

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Credit: NASA/JPL/Space Science Institute

The view looks toward Enceladus across the unilluminated side of the rings from less than a degree above the ringplane.

Blobrana · L

This image of Enceladus was taken in visible light with the Cassini spacecraft narrow-angle camera on Sept. 30, 2007, when the spacecraft was approximately 108,000 kilometres away, at a Sun-Enceladus-spacecraft, or phase, angle of 75 degrees.

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Credit: NASA/JPL/Space Science Institute

The leading hemisphere displays a fresh-looking surface. Only a few craters can be made out in this geologically active moon's surface. A far more heavily cratered, and older, terrain region is visible to the northwest.
The view is centred on 15 degrees north latitude, 109 degrees west longitude.
North on Enceladus is up.

Blobrana · L

Scientists have determined the location of the most powerful jets spraying from the south pole of Saturn's moon Enceladus.
These ejected streams of ice particles come from the hottest spots of geological fractures known as the "tiger stripes".
The results, reported in the journal Nature, delight scientists who study Enceladus, even if they do not come entirely as a surprise.

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