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Space NASA

Cassini Finds Source of Icy Jets On Enceladus 37

Posted by Soulskill
from the nothing-but-net dept.
Not long ago, we discussed Cassini's mission to "skeet-shoot" Saturn's moon Enceladus in order to take high-resolution pictures as close to the surface as possible. Well, NASA scientists found what they were looking for. A newly released mosaic shows 300-meter-deep fractures in Enceladus' surface which are the source of enormous icy plumes that periodically erupt into space, reaching hundreds of kilometers from the moon's surface. Another picture shows one of the fractures in closer detail.
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Cassini Finds Source of Icy Jets On Enceladus

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  • by wisebabo (638845) on Saturday August 16, 2008 @10:40AM (#24626659) Journal

    So anyway this past flyby was at 30 miles at 50,000 mph. I understand that a future one will be done at 15(!) miles altitude (although I don't know the speed).

    I've got to believe that that's the fastest low flyby that's ever been made. With Cassini going by at about 15 miles per second it'll be spinning quite rapidly (a revolution every couple of seconds?) to take one picture right? (there is no camera platform so the entire spacecraft must turn to aim).

    Is there ANY other example of a camera that had to be turned so fast as to catch a moving (relative) target? With calculated precision of course, a photographer turning a camera to de-blur a passing race car doesn't count. There must be even faster motion compensation tricks for missile launches or maybe even roller-coaster rides right? What about industrial processes, anybody have any interesting examples? Then of course, are there any other ONE TIME events when they only had one chance to get it right?

    Of course the other way to get a nice crisp shot would be to use a flash but even at "just" 15 miles it would take quite a flashbulb to illuminate the target sufficiently. Then again Cassini does have about 70kgs of plutonium on board...

  • False color? (Score:5, Interesting)

    by SoundGuyNoise (864550) on Saturday August 16, 2008 @11:00AM (#24626781) Homepage
    Can someone please explain the technical reasons why so many space photos are "false color" based on X-Ray or infrared spectrum, even from modern spacecraft? Is there no color spectrum in outer space?
  • Re:False color? (Score:5, Interesting)

    by RJFerret (1279530) on Saturday August 16, 2008 @11:58AM (#24627195) Homepage

    Can someone please explain the technical reasons why so many space photos are "false color" based on X-Ray or infrared spectrum, even from modern spacecraft? Is there no color spectrum in outer space?

    Of for a great visual comparison, see this flower [naturfotograf.com] in both visual spectrum (ho hum) and false color UV (bull's-eye!).

    Even more impressive is all the details in this otherwise monochromatic flower [naturfotograf.com] that insects see.

    The answer? To get information that our limited eyes can't perceive, into a range we can perceive, and therefore, learn from.

    "In visible-light, a single photon can produce a single electron of charge in a pixel, and an image is built up by accumulating many such charges from many photons during the exposure time. When an X-ray photon hits a CCD, it produces enough charge (hundreds to thousands of electrons, proportional to its energy) that the individual X-rays have their energies measured on read-out." (per X-ray astronomy on Wikipedia [wikipedia.org]) So it's also seems easier to capture these high energy wavelengths.

    Sadly we can't make subtle IR observations from Earth, as the water vapor in our atmosphere absorbs a significant amount of that radiation. (per Infrared astronomy [wikipedia.org])

Sentient plasmoids are a gas.

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