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NASA Space Science

NASA Releases New Photos of Saturn's Rings and Clouds 34

skade88 writes "Launched in 1997, Cassini has taken over 300,000 pictures of Saturn since it started orbiting the planet and the mission is due to run through 2017. NASA has released some new photos including: Saturn's rings, clouds, Saturn's moon Janus, and the shadow of another one of Saturn's moons Mimas."
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NASA Releases New Photos of Saturn's Rings and Clouds

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  • by ClickOnThis ( 137803 ) on Monday December 31, 2012 @02:10PM (#42434223) Journal

    What's with the black-and-white photos? Didn't Cassini have colour cameras?

    • Maybe the same reason moon shots are B&W.

      http://apod.nasa.gov/apod/image/0711/earthrise_kayuga.jpg [nasa.gov] Maybe it is in color.

    • by wonkey_monkey ( 2592601 ) on Monday December 31, 2012 @02:19PM (#42434287) Homepage
      It does, but they cost more to develop. Times are tight.
      • by arth1 ( 260657 )

        Also, most color photos from NASA are gong to be in fake color and exaggerated contrast, made to highlight certain features (or impress congressmen), not to look accurate.

        Personally, I think it's a shame that so many of the most famous pictures from space are heavily retouched and in false colours. The unprocessed imagery is jaw-dropping enough as is. I want to see a "color enhanced" Saturn about as much as I want to see a colour-enhanced Giaconda. You can usually still find the original pictures, but no

        • Re:Black-and-white? (Score:5, Informative)

          by JWW ( 79176 ) on Monday December 31, 2012 @03:36PM (#42435073)

          Also, most color photos from NASA are gong to be in fake color and exaggerated contrast, made to highlight certain features (or impress congressmen), not to look accurate.

          Actually, they don't really have a real color view they can show us. Sensors on spacecraft see multi-band (read color) images as single bands representing intensity for each band. These black and white views are actually the view of a particular band filtered on the wavelength of the light it is looking for.

          The false-color images derived by NASA generally use 3 bands to create a RGB style image with a single particular band standing in for Red, Green, and Blue. The reason these images are false-color is that often the Red band is all or in part filtering to find infrared light, and the blue is sometimes filtered more toward violet and UV.

          They really often times can't make a true color image. Because there is more science value derived from being able to see values in bands that are tuned slightly away from the visible (especially wrt infrared).

        • by drankr ( 2796221 )
          I'm not sure which orbiter took the most recent Jupiter & its moons photos, but I did wonder if the colors were at least nearly accurate. Especially when it comes to Europa.
        • You can usually still find the original pictures, but not always easily.

          Here is a link to one of those original pictures:

          http://www.log24.com/log/pix09A/091127-BlackSquare256-revA.jpg [log24.com]

          (What, your eyes can't see electromagnetic radiation outside the visible light range?)

          (You actually have it completely the wrong way round; it isn't that 'false' color is 'added' - it's that in reality, there are trillions more 'colors' than our very limited human eyes can see.)

    • by Nyder ( 754090 )

      What's with the black-and-white photos? Didn't Cassini have colour cameras?

      B&W film was on sale, with all the NASA cuts they had no choice.

    • Re:Black-and-white? (Score:5, Informative)

      by Anonymous Coward on Monday December 31, 2012 @03:09PM (#42434779)

      From NASA's FAQ page [nasa.gov]:

      Why are so few of the Cassini pictures in color?

      Creating color images is a complex task requiring much more labor and computer time than black and white images. This is because all Cassini images are recorded in black and white. The camera records the amount of light (not the color of the light) coming through a filter in front of the sensor. It is the filters that come in color.

      To create color images scientists take three black and white images of the same target with the red, green, and blue (RGB) filters. In other words, one image records the amount of red light (using a red filter), another records the amount of green and one the amount of blue light (using green and blue filters respectively). Color renditions of the scene are then constructed on the ground by combining images taken with the different filters.
      Unfortunately, these three images are not taken simultaneously. Consequently, intricate fitting and geometric transformations are needed to construct the color image because the spacecraft, planet, rings and moons have all moved a little during the time it takes to record the images using the different filters.

      What controls when a picture is taken?

      The scientists determine this when they do the observation designs. The path of Cassini is known, as are the paths of the Saturn's moons, so it's a matter of looking at the varying geometry with time and selecting the camera pointing directions and shuttering times that will gather the most scientifically interesting images. These commands are then built into sequences that are sent to the spacecraft from days to weeks in advance of the observations.

      • by jez9999 ( 618189 )

        Next question: why don't we just put cameras in space probes that are designed to take colour photos? Maybe it's a dumb question but we don't have any problem with colour digital colour cameras here on Earth...

        • by Synn ( 6288 )

          Because ground cameras aren't designed to travel 1.2 billion km through space. But really I think it's more that the scientists are wanting to record science related data rather than human eye pleasing data and every gram of weight on the probe is precious. So they capture images that are "black and white" and instead use fancy combining techniques on the ground to create a few wowzer color images here and there to please the non-scientist public.

        • Because it all comes down to the resolution of the picture. They want as accurate ans as detailed a picture as they can get, and using a mosaic filter over the sensor firstly fixes you to a single set of colour filters, as it has to be precisely aligned with the image sensor elements, and you have to then interpolate image data (ie, guess at filling in missing colour information)

          With a b&w sensor, you have more freedom in swapping out filters over the sensor and you aren't interpolating picture informat

        • by Tablizer ( 95088 )

          Sure, but the bandwidth bill is coming to you, and it ain't pretty.

          Remember the very first modems? Well, those would be an upgrade in comparison.

        • by meetpi ( 2776369 )

          Not a dumb question at all, it's actually a very good question. The short answer is that an image taken by a standard digital camera would probably be pretty disappointing.

          The first thing to realise is that your eyes aren't really like cameras at all. There's a complex series of interactions in your eyes and brain that take place before you perceive an image. When you take a colour image with a digital camera most people reasonably expect it to match what they see. So, your digital camera manipulates th

        • by Anonymous Coward

          From the Cassini FAQ [nasa.gov] this time:

          What are the camera filters?

          To increase their scientific value, cameras on Cassini have two filter wheels in order to take images at specific wavelengths of light. Some filters only allow light of a certain color to reach the sensor. Combining three such images can produce a color image. Other filters pass light at a specific wavelength absorbed by an element such as hydrogen or methane. This allows scientists to measure where these elements are and at what abundances. Other filters, called polarizers, allow light oriented in a certain direction to reach the sensor. These filters are capable to see through a hazy atmosphere.

          Why are there images of different sizes?
          The Cassini cameras are 1-megapixel cameras. A normal image is 1024 x 1024 pixels. Using a technique called "summation" the cameras have the ability to combine pixels together to get smaller but less noisy images. This results in smaller images that take a lot less time to readout out and take up less data volume. Summation is very useful if a scientist needs to conserve both. In the 2 x 2 mode, the camera takes a 2 x 2 pixel square and averages those values into a single pixel. Images in this mode will be 512 x 512 pixels. In the 4 x 4 mode, the camera takes a 4 x 4 pixel square and makes that a single pixel. Images in this mode are 256 x 256 in size.

          The explanation: "To increase their scientific value" and "to get smaller but less noisy images" for "smaller images that take a lot less time to readout out and take up less data volume". Or in my words, regular cameras don't do good science and are inefficient.

  • Go to the source... (Score:5, Informative)

    by SgtXaos ( 157101 ) on Monday December 31, 2012 @02:15PM (#42434261) Journal


    Has all the images, none of the space.com ads

    • by icebike ( 68054 )

      I've never understood this tendency to post some commercial source when there is a free one with better and more pictures.
      Someone always pimps for Space.com when NASA give you a much better view [nasa.gov].

    • by Anonymous Coward

      From the perspective of somebody who just wants to view some images...

      The nasa site is a little better because the image gallery is less annoying. The main problem with it is the paging. This insistence of UI designers to put everything "above the fold" is ridiculous. Just put all the thumbnails on the page and let the list scroll vertically!

      The space.com images are in a "Carousel" gallery that doesn't work well on large screens or on mobile. As usual it is a narrow fixed screen format that leaves most of t

    • Damn shame slashdot doesn't have editors.
      Maybe we should consider some? I mean, it's no FARK of course.

    • I appreciate what you're trying to do, but honestly, modern NASA sites are as badly designed as any click-bait "news" site. JS that breaks normal browser functionality (like right-click or back). "Interactive" elements that serve only to hide what you're actually looking for.

      Their image sites worked better when they just threw up forty thumbnails per page.

    • by Anonymous Coward

      Also http://ciclops.org/ = site of the people who actually do most of the public release image work, as well as aim the cameras.

  • That one with Titan "floating" in front of Saturn closely reminds me of a work by Chesley Bonestell from the early 50's:

    http://www.daviddarling.info/images/Mimas_Bonestell.jpg [daviddarling.info]

It is not for me to attempt to fathom the inscrutable workings of Providence. -- The Earl of Birkenhead